Research Report

Woodland actions for biodiversity and their role in water managementMarch 2008

Research Report

Woodland actions for biodiversity and their role in water managementMarch 2008

2

INTRODUCTION

The highly fragmented semi-natural habitats

of the UK are vulnerable to climate change.

There is a need to develop landscapes that

are resilient, i.e. able to absorb and respond

to changes, thereby sustaining biodiversity

and ecosystem goods and services.

Woodland actions for biodiversity have an

important role to play ecologically and may

have considerable potential to contribute

to economic and other benefits.

Increasing attention is being given to the

interactions between woodland and water,

as integrated land and water resource

management seeks to address a number of

water issues, including the threats posed by

climate change. While a wide range of

projects have researched or reviewed

particular aspects of water management on

which trees and woodland have an impact,

there is a need for an accessible

overarching synthesis. Technical terms are

asterisked where they appear for the first

time and a glossary is provided at the end

of the document.

AIMS

This report reviews national and international

peer-reviewed and ‘grey’ literature on the positive and

negative, direct and indirect, impacts of trees and

woodland in temperate systems on water resources in

relation to:

� Water quality: turbidity*/siltation* and riverbank stability;

eutrophication*; pesticides and other chemicals;

acidification; water colour/dissolved organic carbon*.

� Water quantity: streamflow*; groundwater recharge*; soil

infiltration* and run-off pathways; base or low flows*; peak

flows*; flood frequency, intensity and risk.

Projected impacts of climate change are taken into

account.

Cover photographs:Top- WTPL/David Rodway. Lower- WTPL/Pete Holmes

3

The report considers the implications for water

resources at a catchment scale, regionally and nationally in

the UK, of:

� Maintaining the existing area of native* and ancient

woodland*.

� Restoring non-native conifer plantations on ancient

woodland sites to native woodland.

� Converting other non-native conifer plantations to native

woodland.

� Planting/regenerating native woodland on arable land,

improved pasture and within urban areas, including

riparian*, wet and floodplain woodland.

� Restoring semi-natural open-ground habitats from

conifer plantations.

Relevant ongoing research is identified, as are

knowledge gaps and research priorities yet to be

addressed.

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LITERATURE REVIEW

Water quality

Forestry can benefit and threaten water quality 2,11,29,93,86,110.

Unmanaged or well-managed woodland is generally beneficial

for protecting water quality.Worldwide, there is growing

designation of native forests as ‘Protection Forests’, often

aimed at stabilisation of steep slopes and reducing avalanche

damage, as well as preserving the quality of drinking-water

supplies. Benefits of forests for water quality are at the

forefront of payment schemes being developed for

ecosystem services in Europe and elsewhere113. Most

instances of woodland causing problems for water quality

arise from poor management or inappropriate design of

non-native plantations and exploitation of timber.

Native woodland aids water quality, as it protects soils from

disturbance due to its management having a generally low

impact. Benefits are greatest where compared to more

intensive land uses, such as agriculture and urban

development. However, native woodland can pose

potential threats linked to interactions between the canopy

and the atmosphere.

Turbidity/siltation and riverbank stability

Woodland can reduce soil erosion and sediment entering

streams by: improving soil structure and stability; increasing

soil infiltration rates; reducing rapid surface run-off; and

providing shelter from wind53,83.The semi-permanent canopy

and benign management, typical of native woodland, minimise

soil exposure and disturbance. One study found less than

1 per cent of observed bare, eroding ground within the

erosion-prone catchment of Bassenthwaite Lake in north

England was associated with native woodland83.

Overseas studies demonstrate the effectiveness of woodland

in reducing soil erosion and maintaining high water

clarity29,22,110.The main risks of woodland increasing turbidity

and siltation follow large-scale windthrow or harvesting,

track construction and cultivation for new planting, which

are not generally associated with native woodland and can be

minimised by best practice.

Many overseas studies demonstrate sediment in water,

draining from adjacent land, is prevented from entering

streams by woodland riparian buffers. For example, one study

found a 30m-wide buffer effectively removed around 80 per

cent of solids suspended in run-off into a Pennsylvanian

stream70, while another reported a 20m-wide buffer

significantly reduced sedimentation following a major storm

event in Newfoundland24. An open woodland canopy,

providing sufficient light to maintain a vigorous understorey

and ground cover, is often regarded as the most effective

land use for retaining sediment7. Large woody debris-dams

within streams have a beneficial effect, trapping and delaying

downstream movement of sediment67.

Native riparian woodland is widely acknowledged as

beneficial for protecting riverbanks and improving

hydromorphological* conditions106.Tree roots bind and

stabilise stream banks, reducing erosion and siltation20. More

stable banks help to maintain deeper channels that favour

fish. Alder is particularly effective at bank protection, as it is

deep-rooting25,93. It is often planted for this purpose but its

dense shading, potential contribution to acidification and

susceptibility to Phytophthora disease118 limit large-scale

planting in many locations.Trampling of riverbanks by farm

animals accessing drinking water is a major cause of bank

erosion, turbidity and siltation. Exclusion of livestock from

native riparian woodland enhances its protective function.

Eutrophication

Water draining from native woodland has a lower nutrient

content than that draining from more intensive land uses29.

This reflects nutrient inputs from the atmosphere usually

matching demand by native woodland, lack of fertiliser

applications and low levels of soil disturbance. Few native

woodland streams are monitored in the UK but studies

elsewhere have found they contain low concentrations of

nitrogen (nitrate and ammonium), phosphate and potassium.

One study found streams draining broadleaved woodland in

the UK were characterised by low nitrate concentrations

with the exception of those draining large areas of alder

woodland (covering 50-80 per cent of the catchment),

although nitrate concentrations were still much lower than

in streams draining intensive farmland41.

Another study looked at the effect of oak woodland on the

quality of groundwater recharge at Clipstone Forest in the

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English Midlands and found concentrations of nitrate,

phosphate and potassium were 13 per cent, 5 per cent and

58 per cent respectively of those in water draining a grass

ley11. Different research found nitrate concentrations were

very variable in groundwater recharge beneath beech and

ash woodland in southern England but averaged less than

half those draining fertilised grassland49. Concentrations

were lowest under ash and highest within woodland

clearings where the beech had been felled or wind blown.

Surprisingly, concentrations were also low close to the

woodland edge, which was thought to be due to the strong

uptake by edge trees.

Tree canopies capture atmospheric pollutants, which can

promote high levels of nitrate in surface and groundwaters in

highly polluted areas.This can be a localised problem where

conifer forests downwind of intensive livestock units

‘scavenge’ ammonia, especially at the woodland edge109, but

this is less of an issue for native broadleaved woodland due

to its weaker scavenging ability49,11.

Broadleaved woodland can provide an effective nutrient

buffer for water draining adjacent land, especially in riparian

zones74,53,93,22. It is effective at removing nitrate in drainage

water, particularly when flow is through the upper soil. For

example, one study found a 30m riparian woodland buffer

removed nitrate to less than detection levels in shallow

groundwater by the River Garonne in France90. Another

study similarly demonstrated that 99 per cent of nitrate

draining from arable fields in southern England during winter

was retained within the first 5m of a buffer planted with

poplar51. Nutrient uptake is strongest during younger stages

of growth and declines rapidly with age. Riparian woodland

buffers are also effective at intercepting phosphate in

drainage waters, especially that carried by sediment.

Catastrophic windthrow or clearfelling of woodland over a

large proportion of a catchment could contribute to

eutrophication, as felling studies have shown sudden

cessation of nutrient uptake can lead to significant increases

in nitrate concentrations in water draining from woodland77.

Pesticides and other chemicals

Native woodland streams are generally free of pesticides and

other chemical pollutants due to absence of inputs.

Herbicides may be used to establish trees in new native

woodland or restocking.This usually entails a single annual

application for two or three years to reduce weed

competition, especially on former agricultural sites.

Herbicides are also used to control rhododendron, laurel,

Himalayan balsam and Japanese knotweed. Best-practice

guidelines place emphasis on selecting chemicals with least

risk of off-site impacts (often glyphosate) and, increasingly,

non-chemical methods of control38. Applications of herbicide

in forestry commonly involves spot treatments by hand and

Bassenthwaite Lake.

Frontal cloud

Wind direction

Emission of pollutantsfrom industry, carsand agriculture

Lowland

Pollutant depositionin rain and snow similarfor forests and other

types of vegetation

Dry depostion of somegaseous pollutants

(HC1, HNO3 and NH3)

N uptake in forest growth

Cap cloud

Rain passes through capcloud and carries S and Npollution to the ground

Pollutants in cloudand mist captured more

easily by forests (becomingimportant above c. 300m)

In many upland areas, base-poor(acidic) soils and impermeable bedrockresults in acidity being quickly passed

to streams in run-off water

Upland

S and N pollutants lifted in aerosol

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Literature review

wide buffer zones*, which also minimise risk of water

contamination. No monitoring assessments of herbicides

have been undertaken in the UK and the few overseas

studies have looked at different chemicals.

Riparian woodland provides an effective buffer for protecting

streams and groundwaters from pesticide applications on

adjacent land. It is particularly efficient at intercepting aerial

drift of pesticides and trapping pesticides bound to sediment

in run-off69. Pesticide residues can be removed from drainage

water by a number of natural processes within woodland

soils, as well as by tree uptake22.

Acidification

Forestry has been implicated in acidification of stream

waters in the UK since acid rain became an issue in the late

1970s85. The primary cause of acidification is the emission of

sulphur and nitrogen pollutants from the combustion of fossil

fuels. However, the quantity deposited, and impact on soil

and water, is strongly influenced by the nature of vegetation

cover, as well as climate and the underlying geology2,81.

Tree canopies ‘scavenge’ pollutants from the atmosphere,

which can contribute to increased acidification within areas

with base-poor soils and geology. Broadleaved woodland

captures less sulphur and nitrogen deposition than conifers

and the impact on surface water acidification is smaller75.

One study assessed the effect of broadleaved woodland on

surface water acidity at a catchment scale and found a link

between the proportion of broadleaved woodland and the

degree of stream acidification of ten acid-sensitive

catchments across the UK41. Broadleaved woodland at less

than 30 per cent cover had no significant effects on

streamwater chemistry.The risk of acidification due to

enhanced pollutant capture will be similar for native

pinewoods and conifer plantations.

Water colour/dissolved organic carbon

Forests can increase water colour in streams draining peaty

soils due to cultivation, drainage and tree growth enhancing

mineralisation of organic matter. Greater colouration can

affect drinking water treatment and represents a loss of soil

carbon38. UK studies have focused on assessing the impact of

upland conifer forests on water colour.These have shown

levels are only marginally higher than in nearby moorland

streams81,77. Broadleaved woodland is unlikely to have a

significant impact on water colour due to absence of drainage

treatments and lower water use compared to conifers.

Water quantity

Plants use water by two processes: transpiration*, whereby

water is taken up from the soil by roots and evaporated

through pores in the leaves; and interception*, involving

direct evaporation from the surfaces of leaves during

rainfall and, in the case of trees and shrubs, from branches

and trunks82.

Figure 1: Acid deposition and forest cover38.

© Crown copyright. Reproduced with permission of the Forestry Commission from Forests & Water Guidelines (2003).

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Trees and woodland can use more water than shorter

vegetation95,114,82,15.Trees have deeper roots and keep

transpiring longer during dry periods, while interception by

woodland can be more than 10 times greater, as trees are

tall, increasing aerodynamic turbulence and thereby

evaporation15.

In the UK, the principal reason for woodland using more

water than shorter vegetation is interception. Evergreen

species maintain high interception rates all year round,

particularly when conditions are wettest and windiest46,18,1,82.

Deciduous trees are typically only in full leaf between June

and September. For around six months of the year, water loss

by deciduous woodland is limited to: interception from

trunks and branches; transpiration from ground vegetation;

and evaporation from soil.

Broadleaved woodland in the UK typically intercepts

10-25 per cent of annual rainfall, compared to 25-45 per cent

for conifer stands46,12,82. Interception is greatest when trees

are in leaf, averaging 40 per cent or more101, in contrast with

3-12 per cent when trees are leafless49,101.Trees with lighter

canopies, such as ash, only intercept 10-15 per cent of annual

rainfall compared to 15-25 per cent by oak and beech49,101.

The deeper rooting of trees can sustain potentially higher

transpiration rates than shorter vegetation in drier parts of

the UK.This effect can be partly limited by the pores on the

needles and leaves of some tree species being very

responsive to dry atmospheric conditions and able to

control water losses99,19. Annual losses from transpiration

occur primarily during the growing season and are generally

in the region of 300-350mm irrespective of woodland type

or species98. Higher values of 390-410mm have been derived

for native broadleaved woodland in southern England, slightly

greater than those from more recent studies (360-390mm)101.

Other factors influencing use of water are woodland

structure and age. Structural diversity in broadleaved

woodland increases aerodynamic roughness and thus

evaporation. However, the impact of this effect is

generally limited to within 20m of the woodland perimeter76.

Variation in tree height, tree density and canopy gaps may

exert an influence but studies of partial conifer thinning

suggest small openings may be unimportant. In Wales, even

the removal of one in three rows of trees only led to a

minor reduction in interception loss from 38 per cent to

36 per cent, perhaps due to the increased canopy ventilation

being compensated by the reduction in leaf area13.

Species diversity affects woodland leaf area, although the

impact on interception is likely to be limited.The presence of

an understorey can make a marked contribution to the

amount of water intercepted but the potential increase in

leaf area tends to be offset by a more open tree canopy

necessary for its development31.

Tree age influences leaf area and efficiency of water use,

which decline with old age51,115,100,104. In theory, this could be a

significant factor for native woodland, especially ancient

woodland, which can have more, older trees. In south-east

Australia, transpiration rates in eucalyptus forest are clearly

related to forest age61, with 230-year-old trees transpiring

less than half that of 50-year-old ones, mainly due to less

conducting sapwood.This greatly outweighs increases in

interception (19 per cent versus 23 per cent) associated with

greater height and structural diversity30. In the USA,

increased water use by young stands regenerated after

timber harvesting has also been recorded5.

Arable crops tend to have the lowest water use due to the

relatively short crop cycle, with significant periods of low

evaporation associated with young growth, ripening and

fallow phases. Annual water use is 370-430mm48, overlapping

with the low end of the range for native broadleaved

woodland of 400mm, assuming 1,000mm annual rainfall81.

However, the difference between woodland and arable crops

Older trees use less water.

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is even smaller and possibly reversed where arable crops

receive irrigation, which increases water use by as much as

100mm per year.

Annual evaporation from short grass crops well supplied

with water is the basis of the Penman potential evaporation

rate, widely recognised as a hydrological benchmark88.Water

use by grass predominantly results from transpiration. Annual

values (400-600mm) overlap with those of native woodland.

Factors limiting water use by grass include a colder climate,

drought and heavy grazing.

Other shorter vegetation with distinctive water use includes

bracken and heather. Bracken has a high annual interception

loss (20 per cent), exceeding that of some native broadleaved

trees119, and its water use (600-800mm for 1000mm annual

rainfall) tends to exceed that of broadleaved woodland.

Heather also has a significant interception loss (16-19 per

cent) due to its fine branch structure, although this is offset

by regulation of its transpiration rate leading to overall water

use of 360-610mm.

Streamflow

Some authors claim native woodland is able to maintain and

possibly increase water yield* compared to short

vegetation22,86. However, evidence indicates the opposite in

most cases54,32,29,33,43,108. A review of historic catchment studies

on forest hydrology, which have been conducted

predominantly in the USA, found that woodland removal was

almost always associated with increased water yield5.

A 10 per cent reduction in woodland cover increased

average annual water yield by 25mm for broadleaved trees

compared to 40mm for conifers but water yield usually

reduced rapidly as the woodland regenerated.These findings

have been confirmed by more recent catchment studies in

Europe but changes are sometimes small and difficult to

separate from climatic variations44,40. Other studies have

found replacement of broadleaved woodland with conifers

produces a highly variable and unpredictable response at a

catchment level. For example, one study concluded that it

was impossible to detect a significant difference in water

yield between maule native forest and plantations of

Monterey pine in central Chile89.

Although no relevant catchment studies have been

undertaken in the UK, modelling of Loch Katrine, a major

water-supply catchment in mid Scotland, predicted

regeneration of native birch-oak woodland over 40 per cent

of the area would only reduce average annual water yield by

2 per cent (and over 70 per cent of the area by 3 per cent)92.

When considering the impact of native woodland on water

yield, absolute changes decline in line with rainfall and run-off

but percentage changes increase. Consequently, absolute

differences are more relevant to wetter climates when

dealing with water supply or hydroelectric requirements,

while percentage reduction is more important in dry regions

with regard to minimum environmental flows.

Groundwater recharge

There have been several major studies in the UK of the

impact of native woodland on groundwater. Assessments of

beech-ash woodland on chalk and ash woodland on clay in

southern England indicated annual recharge beneath

70-year-old beech and 50-year-old ash on chalk, England’s

primary aquifer, exceeded nearby grassland by 17 per cent

and 25 per cent respectively (although not using

contemporary data), while recharge below 70-year-old ash

on clay exceeded grassland by 14 per cent49. A repeat study

of beech on chalk compared with grass (using concurrent

data) found only 13 per cent difference in recharge over an

18-month period101. However, the researchers recently

concluded there may be ‘little overall difference between

broadleaved woodland and grass, either in soil-water

abstraction or in evaporation’ where they overlie chalk, as

it maintains sufficient upward water movement to sustain

high transpiration rates by grass during summer months100.

Other factors involved are the longer growing season of

grass, especially in early spring, and the low interception

loss of ash woodland. Modelling work, however, indicates

that recharge from beneath native woodland could be lower

than grassland in wetter climates because of higher

interception losses101.

Another study compared groundwater recharge beneath

grass, heather, pedunculate oak and Corsican pine overlying

Triassic sandstone in the English Midlands, the UK’s second

most important aquifer11. Estimates based on field and

modelling assessments indicated that, unlike on chalk and

clay, recharge on sand was 16-48 per cent greater under

grass than 60-year-old oak woodland.This may be due mainly

to oak sustaining higher transpiration rates on the drought-

prone sandy soils12,45, as it roots more deeply than grass.

Applied to the likely impact on groundwater resources of

creating a new Community Forest in Nottinghamshire,

increasing woodland cover from 9-27 per cent, recharge was

9

predicted to reduce by 3-6 per cent for oak, compared to

10-14 per cent for Corsican pine.

In the wetter parts of the UK, high interception losses

predominate over possible differences in transpiration,

leading to more water use and less groundwater recharge

under native woodland than grassland.

Soil infiltration and run-off pathways

It has been noted that soils can affect water use and yield by

influencing transpiration rates. Soil type and condition are

also important for determining pathways and consequent

timing of water draining from soils into streams and rivers.

Shallow, poorly draining soils have superficial pathways and a

fast catchment response to rainfall, resulting in high peak

flows. Deep, freely draining soils promote deeper water

pathways and a delayed, attenuated response.

Woodland protects soils and often improves their condition,

as compared to more intensive land uses35. Native woodland

rarely involves the formation of continuous cultivation

channels or drainage treatments to aid establishment. Lack of

disturbance helps to increase soil organic matter and

improves soil structure, resulting in an increased ability to

receive and store water, commonly referred to as a ‘sponge

effect’*84. Recent studies at Pont Bren in Wales found

soil-infiltration rates were up to 60 times higher under

young native woodland than heavily grazed pasture4.

Soil-infiltration rates appeared to improve by 90 per cent

within two years of stock removal and woodland planting.

Base or low flows

Woodland has long been associated with augmenting base

flows in rivers due to the ‘sponge effect’122,64,94. However,

others believe greater water use by woodland is likely to

outweigh higher infiltration rates and delayed release of

water from woodland soils97. Many studies have found felling

of native woodland increases catchment water yield and base

flows. For example, one study found removal of natural

woodland in Taiwan increased low flows by 91 per cent57,

while another demonstrated natural regeneration of

broadleaved woodland over the last 50 years has led to

long-term reduction in dry-season flows in the Dragonja

catchment, Slovenia44.

The most detailed study of the impact of woodland on flows

analysed 28 catchments across Europe102. The authors

concluded that while there are specific local situations where

woodland management (drainage and clearfelling) can

increase, or growth of conifers can decrease, low flows by

10-20 per cent, the effect is relatively small at the European

or regional scale.The partial felling of central European

mixed native broadleaved and Mediterranean native open

forests had no detectable effect on base flows.This is

supported by another study that found low flows in upland

catchments were largely determined by local geology and

soils, not land use85.

Peak flows

The woodland ‘sponge effect’ is commonly associated with a

reduction in peak flows73,53. Many felling experiments have

demonstrated an increase in peak flows for several years

after woodland clearance, until new trees become

established101,105. Some have argued this is due to soil

compaction and ground damage from timber extraction but

the effect has been replicated where best practice has been

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Intensively managed soils can have lower infiltration rates.

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employed.These short-term studies limit assessment to

annual or lesser peak flows.The impact of woodland on

more extreme events has not been evaluated.

Research has only considered upland conifer afforestation

and clearfelling, which was reviewed in 2003 as part of a

wider EU study102.This found that growth of conifer forests

could reduce annual peak flows by 10-20 per cent in

completely afforested headwater catchments*, while forest

drainage and felling had the opposite effect. As with base

flows, partial clearance of native mixed broadleaved or

Mediterranean open forests had no detectable effect on

peak flows.

Flood frequency, intensity and risk

Most UK studies have focused on upland conifer forests but

found no significant effect at the headwater or large

catchment scale103. A review of regional flood studies in

Britain determined woodland area was not significant in

flood prediction, although percentage woodland cover was

generally small79. Other reviews found woodland reduces

small ‘muddy’ floods at hillslope or headwater catchment

scales but little evidence of significant impact on extreme

events or flood risk at regional or large catchment

scales71,102,87. A number of worldwide assessments have also

failed to discover evidence of any forest type preventing

large-scale major floods, even in predominantly forested

catchments, and considered the impact of forests on

floods to be limited to catchments less than 100 km2 in

area33,15. A recent global study6 , analysing data from satellite

observations at the country scale, has claimed flood

frequency and duration decline with increasing native

woodland cover but the opposite for non-native plantation

forest. However, this study excluded extreme flood events

and the robustness of the approach has been questioned by

other workers.

Floodplain woodland can have a mitigating effect on large

flood events, absorbing and delaying release of flood

flows53,92,22,97,55. Mathematical modelling found greater

hydraulic roughness created by a 2.2km reach of floodplain

woodland on the River Cary in south-west England increased

flood storage by 71 per cent and delayed the flood peak

progressing downstream by 140 minutes for a one-in-a-

hundred-year flood event111.This was considered significant in

potentially protecting downstream sites from inundation.

Field testing is required. Studies of riparian woodland have

shown large woody debris-dams in headwater streams can

retard generation of flood flows67. However, there are

concerns that wash-out of woody debris could block bridges

and other structures, increasing risk of downstream flooding.

Floodplain woodland can reduce and delay flood flows.

11

KEY CAVEATS TO THE LITERATURE REVIEW AND ITS APPLICATION TO THE UK

Native woodland and forestry in the UK

A distinction is made between conifer forest and broadleaved

woodland in the UK, and between UK forestry and forest

management elsewhere in the temperate zone. Most conifer

forests in the UK have been planted in the last 90 years as

monocultures for commercial timber production.

Concentrated in the uplands, the wettest parts of the UK,

sites for conifer planting have been cultivated and, crucially,

drained to ensure establishment. Silviculture can involve

frequent thinning on more stable sites, and often clearfelling.

These intensive forestry operations have the potential to

have a high impact, although this is increasingly controlled by

improved forest design and best management practices. By

contrast broadleaved woodland in the UK has generally been

around longer and is predominantly lowland. Broadleaved

woodland is rarely drained and silvicultural systems are

generally low impact. Elsewhere in the world, temperate

forestry is focused on a long-established forest resource and,

unlike in the UK, is more often based on selective harvesting

and regeneration rather than afforestation and clearfell. It is

important to understand this distinction in drawing

conclusions from studies across temperate zones and

applying their findings to the UK.

Quantification

The impact of native woodland on water resources is

affected by many factors and there has been limited

quantification in the UK. Overseas research needs interpreting

with caution due to differences in climatic conditions, soil

types and woodland species (e.g. many studies consider

mixed conifer and broadleaved stands).The majority of

historic catchment studies on forest hydrology have been

conducted in the USA. No studies have measured the effect

on streamflow and water yield of changing land use from

short vegetation to mature broadleaf woodland due to the

timescale involved. Research has focused on the impact of

woodland clearance on catchment water yield. Impacts of

woodland clearance cannot simply be used to infer changing

water yield for new woodland as it matures.This is because

of: the lack of a suitable control (comparison only possible

with clearfelled site); the partial nature of felling treatments,

in many instances; and the potential for harvesting to

complicate results, due to levels of disturbance.

Scale

Empirical evidence of the impacts on water resources of

trees and woodland comes from studies of individual trees,

stands and localised research. Extrapolating findings is

complicated by a range of variables as scale increases.

Within individual sites, diversity of woodland structure and

tree species tend to increase with area, as does the

proportion of open habitats, roads and tracks. Moving to a

larger catchment scale or beyond, land use patterns and

management practices become ever more complex, as do

variations in topography, geology, soils, rainfall, snowmelt

and run-off pathways80,84, woodland type, age and growth

rates116,59.This limits understanding of interactions between

land use and land-management practices on water at the

river-basin scale.

As the percentage of woodland cover declines, its signature

is diluted by other land uses. Similarly, it may be difficult to

identify impacts on water against natural background

variation when less than 20 per cent of a catchment is

subject to woodland creation or removal24. Smaller-scale

woodland creation may nevertheless have a discernible

impact on both flood flows and water quality at a local level,

if it is appropriately targeted (e.g. within riparian zones)83.

This is particularly relevant, as the UK has less than 12 per

cent woodland cover.

Seasonality

Seasonality is a significant factor affecting water use and its

impact on water resources.Transpiration loss from grass

starts earlier in the year than broadleaved woodland;

however, drought can lead to early ageing of grass and

shorten the growing season12.This can influence seasonal

flows, although timing depends on the amount of water

stored in underlying soils and rock and the lag in drainage

waters reaching rivers.Phot

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POLICY CONTEXT

Impacts of climate change on woodland and water

Climate change projections for the UK are generally for

warmer, wetter winters and hotter drier summers with

more prolonged droughts, particularly in the south, and

evaporation totals increasing in all regions82,17,61.The potential

impacts on water resources and flood control are significant

and are expected to become more challenging in the future91.

Water supplies are already severely stretched in some parts

of the UK, particularly the south, while at the same time

growing pressure for housing development on floodplains

and rising property values are increasing the flood hazard27.

Impacts on water quality could also be significant with less

water to dilute pollutants. Rising temperatures will increase

thermal stress for freshwater life.

Implications for woodland and water in the UK

Projected changes in climate are expected generally to lead

to increased evaporation and reduced water yields from both

woodland and non-woodland areas.Warmer temperatures

increase potential evaporation rates and lengthen the

growing season and higher atmospheric carbon-dioxide

levels could enlarge total leaf area82. Ultimately, if potential

evaporation rates far exceed rainfall inputs, water use by

all vegetation-types will converge16. Nevertheless in

water-scarce areas, for the foreseeable future, large-scale

woodland creation may need to be restricted50 and species

with a high water demand possibly avoided.

Most climate change scenarios lead to projected increases in

flood magnitude, although its significance and timing is less

certain17.The presence of woodland could serve as a buffer

against excessive run-off and reduce annual peak flows

(e.g. in the West Weald,West Sussex53) but this may only be

significant in relatively small catchments where woodland is

predominant29.Targeted floodplain woodland creation could

alleviate flood risk55,84.

The main evidence of an effect of climate change on water

quality is the widespread rising trend in dissolved organic

carbon concentrations in many upland streams across the

UK and Europe.Thought to result from increased

mineralisation of soil organic matter due to a warming

climate38, dissolved organic carbon concentrations, and

associated water colour, tend to be marginally greater in

conifer forest streams but are unlikely to be affected by

broadleaved woodland. Climate change may also affect water

quality indirectly by stimulating land use changes that bring

diffuse pollution to new areas56.This might be reduced by

targeting woodland creation to source areas, pollutant

pathways* and as a buffer to riparian zones. Planting

riparian woodland would have the additional advantage of

providing shade to help moderate the impact of rising

water temperatures on sensitive freshwater life, especially

salmonid fish.

Climate change is likely to have a significant bearing on future

planting and management of native woodland.The Climate

Change Programme and Energy Reviews that are underway

may help to clarify woodland’s role in mitigation and

adaptation. There is significant scope for harvesting of more

biomass from native broadleaved woodland.

EU Water Framework Directive

Woodland could play an important role in helping meet

objectives of the EU Water Framework Directive, including:

to protect and improve the status of Europe’s rivers, lakes,

groundwaters, estuaries and coastal waters; to promote the

sustainable use of water resources; and to help reduce effects

of flooding and drought.

Tewkesbury 2007: major flooding put the spotlight on water policy.

13

A key target of the EU Water Framework Directive is for

rivers to achieve good ecological and chemical status by 2015.

This is a major challenge, with 93 per cent of rivers in

England and Wales at risk of failing to achieve it (Figure 2).

The two most important threats are diffuse pollution and

physical changes, often associated with agriculture and urban

development.The main sources of diffuse pollution responsible

for at-risk water bodies are: sediment delivery (21 per cent),

pesticides (21 per cent), phosphorus (47 per cent) and

nitrate (38 per cent). Some 48 per cent of rivers are also at

risk from physical degradation of river channels and banks.

New native woodland creation has potential to reduce

pressures by protecting soils and riverbanks, reducing rapid

surface run-off and intercepting pollutants before they reach

watercourses. Although this is scale-dependent, benefits

could be maximised by targeting high risk soils and careful

placement of woodland to intercept pollutant pathways.This

Figure 2: Percentage of water bodies in England and Wales at risk of notachieving EU Water Framework Directive objectives31a.

would require better integration of farming and woodland

within catchments. River-basin management planning is a key

mechanism within the EU Water Framework Directive for

delivering improvements to the water environment.

If due care is taken, native woodland has significant potential

to sustain water quality and alleviate flooding through its

effects on run-off pathways and flood flows, without posing

additional problems for water resources and droughts.The

Environment Agency in England and Wales has developed

Catchment Abstraction Management Strategies and Catchment

Flood Management Plans for catchments identified at risk

from low flows and flooding, and for groundwater bodies at

risk of not meeting good quantitative status.

UK Biodiversity Action Plan

The UK Biodiversity Action Plan sets targets for priority

species and habitats to guide conservation action. Climate

change is now recognised as a significant factor that was not

taken into account when the original UK targets were set.

The targets were reviewed in 2005-6 and are designed to

improve the long-term viability of habitats and species

populations.

The following targets have been set that relate to woodland:

� Maintain the extent of native woodland in the UK (no net

loss of one million hectares).

� Maintain the current extent and distribution of ancient

semi-natural woodland, which qualifies as native woodland

in the UK (no change in the existing area of 403,000ha).

� Restore 50,300ha of non-native plantations on ancient

woodland sites to native woodland in the UK by 2015.

� Expand the current native woodland resource in the UK

by 134,500ha by 2015 through a combination of

converting (restocking) existing plantations not on ancient

woodland sites and creating native woodland on former

agricultural land.

� Expand semi-natural open-ground habitats (which will

include restoration where planted with non-native

conifers), e.g. lowland heathland by 7,600ha by 2015.

Pressures Rivers Lakes Estuaries Coastal Waters Groundwater

Point discharges 23.1 20.1 48.5 18.2 3.9

Diffuse pollution 82.4 53 25 24.2 75.3

Abstraction 10.7 2.1 14 Not applicable 26.1

Physical changes 48.2 59.3 89.7 77.8 Not applicable

Alien species 21.1 9.3 98.5 45.5 Not applicable

Overall % ofwater bodies at risk 92.7 84 98.5 84.5 75.3

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LIKELY IMPLICATIONS FOR WATER RESOURCES OF WOODLAND ACTIONS FOR BIODIVERSITY

Maintaining the existing area of native and ancient woodland

The main impacts on water resources can be

summarised as:

� Preservation of high quality drainage waters with low

nutrient, pesticide and sediment concentrations due to

lack of soil disturbance.

� Maintenance of good or high ecological status of water

bodies draining catchments dominated by native

woodland, except possibly for Scots pine within acid

sensitive areas.

� Reduction in water use and increased water yield as

younger woodland matures.

� Maintenance of water yield, and probably base flows,

across large parts of central and southern England

overlying chalk or clay soils (likely to be within plus or

minus 10 per cent of that from grassland).

� Reduction in water yield, and probably base flows, in dry

parts of England (less than 750mm annual rainfall)

overlying sandy soils (likely to be 20-50 per cent less than

from grassland).

� Reduction in water yield in wet parts of the UK (greater

than 1,500mm annual rainfall) (up to 10 per cent less than

grassland).

� Reduction in small (less than one in every five years)

floods (10-20 per cent less than grassland).

Effects on water yield may be reduced with increasing size

of woodland, as structural and species diversity grows and

edge effects have proportionally less significance. It is

unlikely that small differences in water use expected

between different native broadleaved tree species could

ever justify species management to limit impacts on water

quantity. Conversion of native pinewoods to birch could

yield significantly more water but within its native range

there is no demand.

Based on the review of impacts of trees

and forests on water resources, likely

implications for water resources of

woodland actions for biodiversity in the

UK are outlined below.

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Restoring non-native conifer plantations on ancient woodland sites to native woodland

This would benefit both water quantity and quality, except

where restoration is to native conifer woodland. Main

impacts might be:

� Increase in water yield, and probably base flows (by

20–50 per cent in dry regions and up to 10 per cent in

wet parts of UK), unlikely to be noticed at the level of a

large surface or groundwater body but could be locally

significant, although slow to develop if restoration is

gradual.

� Increase in small (less than one in every 5 years) floods

(less than 10 per cent) due to lower water use and greater

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run-off from broadleaved woodland, especially during

winter and early spring when floods are most frequent.

� No effect on extreme floods.

� Reduction in threats to water quality following

restoration, although these would have been greatly

constrained by the Forests & Water Guidelines38.

� Local improvements in water quality, greatest in areas

subject to continued acidification, where the weaker

scavenging effect of native broadleaved woodland will

reduce the impact of acid deposition.

� Sizeable reduction (up to 90 per cent) in nitrate

concentrations in very dry regions (less than 600mm

annual rainfall); elsewhere, little change.

16

Likely implications for water resources of woodland actions for biodiversity

Converting other non-native coniferplantations to native woodland

The effects of converting plantations more generally are

expected to be similar to those outlined immediately above.

Once again, changes to both water quantity and quality are

unlikely to be significant where conifer plantations are

converted to native pinewoods. An anticipated additional

impact is an increase in flood retention where conifer

plantations on floodplains are converted to native woodland,

as hydraulic roughness would be increased by development

of a shrub layer, ground cover and increasing levels of

deadwood. Ancient woodland on ground liable to flooding is

rare, as it was historically the most valuable land as

meadow95, but conifer plantations on sites without a long

history of woodland cover occur on floodplains

Throughout the UK, consideration is being given to continuous

cover forestry as a means of managing large areas of conifer

plantations.This silviculture creates a certain degree of shrub

cover and age diversity in the crop but evidence would suggest

limited benefits for water yield.

Restoring semi-natural open-ground habitats from conifer plantations

Restoration can be expected to benefit water quantity, and

to a lesser extent water quality, depending on how these

areas are subsequently managed. Adverse effects could result

from large-scale felling to waste, chemical and cultivation

treatments to control conifer regeneration, burning or use

of livestock for vegetation management, although good

practice will minimise these risks. In general, impacts are

expected to be:

� Local improvements in water quality greatest in areas

subject to continued acidification, where removal of the

scavenging effect will reduce the impact of acid

deposition.

� Substantial reduction (up to 90 per cent) in nitrate

concentrations in dry regions (less than 600-650mm

annual rainfall), as conifers have a marked evaporation-

concentration effect.

� Reduction in speed of surface run-off from blocking forest

drains and cultivation channels on peatland but countered

by increased volume of run-off and possible reduction in

available soil water storage.

Heathland restoration from conifer plantation. Phot

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Planting/regenerating native woodland on arable land, improvedpasture and urban areas

Available evidence suggests native woodland creation on

more intensively managed land will benefit water quality

status but may pose issues for water resources. Impacts are

expected to be:

� Improvement in water quality, as it removes the need for

regular soil disturbance/cultivation and fertiliser and

pesticide treatments, especially where it replaces

potentially damaging land uses on sensitive soils (e.g.

improved grassland and arable overlying soils prone to

erosion and nutrient loss).

� Reduction in sediment, nitrate, phosphate and pesticide

concentrations (by as much as 90 per cent possible) by

aiding soil infiltration, retaining suspended particles,

binding nutrients and pesticides and promoting nutrient

removal via tree uptake.

� Reduction in nitrate concentration linked to scale of

planting and significant decrease in sediment, phosphate

and pesticide levels achieved by small-scale targeted

planting of source areas and pollutant pathways, where

surface run-off emerges or seepage occurs close to the

surface (e.g. downslope boundaries of steep fields, springs,

purpose-built infiltration basins/swales, riparian zones and

associated wetlands).

� Retention of chemical pollutants on brownfield sites,

through use of trees in sustainable urban drainage

systems* to aid soil infiltration, increase soil organic

matter levels, reduce drainage volumes and protect soil

from disturbance (taking care to avoid mobilising some

pollutants through soil acidification).

� Increase in water yield and probably base flows

(by 50-100 per cent in dry regions and up to 20 per cent

in wet areas).

� Increase in small (less than one in every five years) flood

events (less than 20 per cent).

� Effects of small-scale restoration (less than 20 per cent of

the area of the surface/groundwater body or catchment)

unlikely to be detected at the level of a main surface or

groundwater body.

� No effect on extreme flood flows.

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Likely implications for water resources of woodland actions for biodiversity

� Shade provided by new riparian woodland moderating the

impact of rising water temperatures on sensitive

freshwater life, especially salmonid fish.

� Reduction in surface run-off and groundwater recharge

where woodland created on arable and brownfield land, as

woodland generally uses more water, unless the arable

relies on irrigation. Lighter-foliaged trees, such as ash,

would limit the difference, although reduction would still

be expected on drought-prone soils and in wetter areas.

Planting on grassland would also reduce surface run-off

and groundwater recharge, except on chalk or clay soils in

areas of intermediate rainfall where they could be

marginally increased.

� Little change to water yield, and probably base flows,

where woodland created on grassland across large parts

of central and southern England overlying chalk or clay

soils (likely to be within plus or minus 10 per cent).

� Reduction in water yield, and probably base flows, in dry

parts of England (less than 750mm annual rainfall).

overlying sandy soils (likely to be 20-50 per cent less than

grassland).

� Reduction in water yield where native pinewoods or yew

woodland created, regardless of existing land cover.

� No significant effect on water yield, base or peak flows

where scale of planting is less than 20 per cent of surface

or groundwater body.

� Reduction in small (less than one in every five years)

floods (10-20 per cent), as a result of improved soil

infiltration reducing local peak flows (where water

resources are not in short supply, selection of species

with higher water use, such as poplar and willow, could

further aid attenuation of summer floods)

� Possible reduction in extreme floods downstream by new

riparian or floodplain woodland, although local upstream

properties would be at risk from the backwater effect and

potential for large woody debris release to block critical

structures downstream (e.g. bridges and culverts).

� Improvements to riverbank and in-stream physical habitat

through bank protection, woody debris-dam formation,

leaf fall and shading.

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KNOWLEDGE GAPS AND RESEARCH NEEDS

A combination of targeted field and modelling studies are

required to:

� Quantify the impact of upland native woodland on water

quantity and water quality at the catchment scale, as most

hydrological studies have focused on conifer plantations.

� Field test models and further quantify the impact that

new native floodplain woodland can have on mitigating

large flood events.

� Further quantify effects of targeted planting of native

woodland on diffuse pollution within agricultural

catchments, specifically in relation to infiltration

basins/swales, riparian buffers, source areas and pollutant

pathways.

� Develop best practice on managing floodplain woodland

in terms of benefits and potential threats (e.g. from the

release of large woody debris) to flood defence.

� Quantify the water use of a wider range of native

woodland species and the effect of woodland design and

structure on woodland evaporation120.

� Quantify the effects on flood flows and diffuse pollution

control of using woodland within sustainable urban

drainage systems.

� Quantify the economic costs and benefits of native

woodland impacts on water and evaluate the case for

payments for water services in the UK.

� Develop an improved climate change water use impacts

model that can take account of species differences under

present and projected climate scenarios to support

operational decision-making.

� Monitor the long-term effects of native woodland on the

freshwater environment.

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CONCLUSION

The key interactions between woodland and water

management are summarised below:

� Broadleaved woodland can substantially improve

water quality, as it removes the need for regular soil

disturbance/cultivation and fertiliser and pesticide

treatments, especially where it replaces potentially

damaging land uses on sensitive soils (e.g. improved

grassland and arable overlying soils prone to erosion

and nutrient loss)

Delivery of targets in the UK Biodiversity

Action Plan for maintenance, restoration

and expansion of native woodland, as well

as restoration of semi-natural

open-ground habitats from conifer

plantations, could make important

contributions to meeting some of the

objectives of the EU Water Framework

Directive and provide some opportunities

to help meet the EU Floods Directive.

21

ACKNOWLEDGEMENTS

This work was funded by the Woodland Trust and the

Forestry Commission.We are grateful for comments

received on drafts of the report from: Steve Gregory, Helen

McKay, Derek Nelson and Sallie Bailey (Forestry

Commission); Mark Diamond (Environment Agency); Nick

Collinson, Fran Hitchinson and Mike Townsend (Woodland

Trust). The document is a review and is not intended to

reflect the policy positions of any of the organisations

involved.

� Annual water yield from broadleaved woodland is

expected to be greater than from conifer plantations

but potentially less than from grassland or arable. Risk

of woodland creation reducing water yield depends

on climate, geology and woodland design and can be

managed by selecting species that use less water

� Woodland has the potential to reduce low flows. Risk

is greatest for conifers on deeper lowland aquifers

and lowest for broadleaved woodland on shallower

upland aquifers

� Broadleaved woodland can reduce small ‘muddy’

floods at a local scale and on floodplains can mitigate

large flood events, absorbing and delaying release of

flood flows. Models suggest the impact of floodplain

woodland could be significant but field testing is

required.

The impacts of woodland on water quantity tend to be

related to the extent of woodland cover within a

catchment. Effects are very difficult to detect when

woodland creation or removal involves less than 20 per

cent of the area. Scale tends to be less important for

water quality due to the localised nature of many

pollution sources and the success of targeted measures.

There is an urgent need for further research to quantify

the relative impact of native woodland on water

quantity and quality, as compared to other land cover. It

is vital that the effect of continuing native woodland

expansion on the status of water bodies and

groundwater supplies is assessed to build on current

limited evidence.

An opportunity is presented at Loch Katrine, one of the

most important public-water-supply reservoirs in

Scotland, where Forestry Commission Scotland is

initially planning to increase native woodland cover to

2,000ha (18 per cent cover) with significant scope for

more. Planting of demonstration floodplain woodland

across the UK is also required to facilitate research and

aid communication.

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22

1 Ahmad-Shah,A. and J. O. Rieley (1999) “Influence of tree canopies on the quantity of water and amount ofchemical elements reaching the peat surface of a basin mire in the Midlands of England”. Journal ofEcology, 77, pp. 357-370.

2 Alexander and Cressner (1995) “An assessment of the possible impact of expansion of native woodlandcover on the chemistry of Scottish freshwaters”. Forest Ecology and Management, 73, pp. 1-27.

3 Best,A., L. Zhang,T. McMahon,A.Western and R.Vertessy (2003) “A critical review of paired catchmentstudies with reference to seasonal flows and climatic variability”. Murray-Darling basin Commission andCSIRO.

4 Carroll ZL, Bird SB, Emmett BA, Reynolds B, Sinclair FL (2004) “Can tree shelterbelts on agricultural landreduce flood risk”. Soil Use and Management, 20, pp. 357-359.

5 Bosch, J. N. and J. D. Hewlett (1982) “A review of catchment experiments to determine the effect ofvegetation changes on water yield and evapotranspiration”. Journal of Hydrology, 55, pp. 3–23.

6 Bradshaw, C.J.A., N.S. Sodhi, K.S.-H. Peh and B.W. Brook (2007) “Global evidence that deforestationamplifies flood risk and severity in the developing world”, Global Change Biology, 13, pp. 1-17.

7 Broadmeadow, S. and T. Nisbet (2004) “The effects of riparian forest management on the freshwaterenvironment: a literature review of best management practice”. Hydrology and Earth System Sciences, 8,Issue 3, pp. 286-305.

8. Bromley, M. (2006) “Forestry and the water framework directive- an update”.Agenda Item 5, NationalCommittee for Wales, Forestry Commission,Wales, 4 pages.

9 Calder, I. R., R. J. Harding and P.T.W. Rosier (1983) “An objective assessment of soil moisture deficitmodels” Journal of Hydrology, 60, pp. 329-355.

10 Calder, I. R., R. L. Hall, P.T.W. Rosier, H. G. Bastable and K.T. Prasanna (1996) “Dependence of rainfallinterception on drop size: 2. experimental determination of the wetting functions and two-layer stochasticmodel parameters for five tropical tree species”. Journal of Hydrology, 185, pp. 379-388.

11 Calder, I. R., I. Reid,T. R. Nisbet,A.Armstrong, J. C. Green and G. Parkin (2002) “Study of the potentialimpacts on water resources of proposed afforestation”. Final report of contracts CWO 633-I and CWO633II (Trees and Drought Project on Lowland England – TaDPoLE) to the Department for theEnvironment, Food and Rural Affairs publication, 179 pages.

12 Calder, I. R., I. Reid,T. R. Nisbet and J. C. Green (2003) “Impact of lowland forests in England on waterresources: application of the Hydrological Land Use Change (HYLUC) model”.Water Resources Research,39, 1319 pages.

13 Calder, I. R. (1990) “Evaporation in the uplands”. John Wiley and Sons, Chichester, 148 pages.14 Calder, I. R. (2005) Second Edition “The Blue Revolution, Integrated Land and Water Resource

Management”. Earthscan Publications, London: UK, 352 pages.15 Calder, I. R. and Aylward, B. (2006) “Forests and floods: moving to an evidence-based approach to

watershed and integrated flood management”.Water International, 31, issue 1, pp. 87-99.16 Calder, I. R.,T. Nisbet and J.A. Harrison (2007) “An evaluation of the impacts of energy plantations on

water resource in the UK under present and future UKCIP02 climate scenarios”. Contract Report toForestry Commission (in press).

17 Cameron, D. (2006) “An application of the UKCIP02 climate change scenarios to flood estimation bycontinuous simulation for a gauged catchment in the northeast of Scotland, UK (with uncertainty)”. Journalof Hydrology, 328, pp. 212-226.

18 Cannell, M. G. R. (1999) “Environmental impacts of forest monocultures: water use, acidification, wildlifeconservation and carbon storage”. New Forests, 17, pp. 239-262.

19 Carling, P.A., B. J. Irvine,A. Hill and M.Wood (2001) “Reducing sediment inputs to Scottish streams: areview of the efficacy of soil conservation practices in upland forestry”.The Science of the TotalEnvironment, 265, pp. 209-227.

20 Castelle,A. J.,A.W. Johnson and C. Connolly (1994) “Wetland and stream buffer size requirements- areview”. Journal of Environmental Quality, 23, pp. 878-882.

21 Chomitz, K. M. (2006) “At Loggerheads? Agricultural expansion, poverty reduction and environment in thetropical forests”.World Bank Policy Research Report:Washington, D. C.

22 Cook, D,T. Greeenaway and F. Southgate (2005) “Sussex Floodplain Forest Concept Study”. Report of theRecord Centre Survey Unit, 139 pages.

23 Cornish, P.M. (1993) “The effects of logging and forest regeneration on water yields in a moist eucalyptforest in New South Wales,Australia”. Journal of Hydrology, 150, pp. 301-322.

24 Curry R.A., D.A. Scruton and K. D. Clarke (2002) “The thermal regimes of brook trout incubation habitatsand evidence of changes during forestry operations”. Canadian Journal of Forest Research, 32, issue 7, pp.1200-1207.

25 Davies-Colley, R. J. (1997) “Stream channels are narrower in pasture than in forest”. New Zealand Journalof Marine and Freshwater Research, 31, pp. 599-608.

26 Defra (2006a) “England’s trees, woods and forests: a consultation document”. Department for theEnvironment Food and Rural Affairs, 53 pages.

27 Defra (2006b) “Water supply in the long term - Water Saving Group outlines progress on action plan”.Department for the Environment Food and Rural Affairs, News Release 20 June 2006.

28 Delzon, S. and D. Loustau (2005) “Age-related decline in stand water use: sap flow and transpiration in apine forest chronosequence” Agricultural and Forest Meteorology, 129, pp. 105-199.

29 Dudley, N. and S. Stolton (2003) “Running Pure:The importance of forest protected areas to drinkingwater”.World Bank and WWF Alliance for Forest Conservation and Sustainable Use publication, 114pages.

30 Duncan, H.D., K.J. Langford and P.J. O'Shaughnessy (1978) “A comparative study of canopy interception”.Proceedings of Institute of Engineering Australia, Hydrology and Water Resources Symposium, Canberra,Institute of Engineers, Canberra, pp 150-154.

31 Environment Agency (1998) “Broadleaf woodlands: the Implications for water quantity and quality.31a Environment Agency (2005) Assessing risks to the water environment River Basin Characterisation -

Results 2005.32 Fahey, B. and R. Jackson (1997) “Hydrological impacts of converting native forests and grasslands to pine

plantations, South Island, New Zealand”.Agricultural and Forest Meteorology, 84, pp. 69-82.33 Food and Agriculture Organisation (2005) “Forests and floods: drowning in fiction or thriving on facts”.

RAP publication 2005/03, Forest Perspectives 2. Food and Agriculture Organisation, Regional Office forAsia and the Pacific: Bangkok,Thailand.

34 Farley, K.A., E. G. Jobbagy and R. B. Jackson (2005) “Effects of afforestation on water yield: a globalsynthesis with implications for policy”. Global Change Biology, 11, pp. 1565-1576.

35 Forestry Commission (1999) “A new focus for England’s woodlands: strategic priorities and progress”,England’s Forestry Strategy, 36 pages.

36 Forestry Commission (2000) “Forests for Scotland”, Scotland’s Forestry Strategy, 92 pages.37 Forestry Commission (2001) “Woodland for Wales”,Wales’ Forestry Strategy, 48 pages.38 Forestry Commission (2003) “Forests & Water Guidelines”, Fourth edition, Forestry Commission,

Edinburgh, 66 pages.39 Forestry Commission (2005) “Forestry Statistics 2005”.

http://www.forestry.gov.uk/website/foreststats.nsf/byunique/woodland.html.

BIBLIOGRAPHYGLOSSARY OF KEYTECHNICAL TERMS

Ancient woodland Believed to have been continuously wooded since atleast 1600 AD. Before this planting was uncommon, soit was likely to have developed naturally.

Base or low flows Extreme minimal flow of water in a water body.

Buffer zone Area of natural or specifically selected vegetationbetween a water body and adjacent land use whosepurpose is to protect water quality from potentialthreats.

Dissolved organic Compounds found in water derived from organiccarbon materials (e.g. decomposed plant matter)

Eutrophication Pollution caused by excessive plant nutrients (primarilyphosphorus, nitrogen and carbon). Growth of algaepromoted by these nutrients potentially changes waterquality leading to oxygen depletion and fish deaths.

Groundwater recharge Process by which groundwater is replenished by watersoaking into the ground

Headwater catchment The area drained by small streams in the upperreaches of land that feeds into a water body such as astream, river or lake.

Hydromorphology Physical characteristics of a water body, includingbanks and bed.

Interception Direct evaporation of rainfall from surfaces of leaves,branches and trunks.

Native woodland Predominantly composed of native species; covers aspectrum from pure broadleaved through to nativepinewoods, which include an element of broadleaves.

Peak flows Extreme maximum flow of water in a water body.Magnitude of peak flow events has traditionally beencharacterised in terms of the ‘return period’: thelonger the return period, the larger the peak event.

Pollutant pathways Known or identified avenues for the transport ofpollutants.

Riparian zone Land adjacent to a water body.

Siltation Sediment input to a water body.

Soil infiltration Process by which water on the surface enters the soil,governed by two forces: gravity and capillary action.Smaller pores offer greater resistance to gravity butvery small pores pull water through capillary action.

Sponge effect Lack of disturbance helps to increase soil organicmatter and improves soil structure in woodland,resulting in an increased ability to receive and storewater.

Streamflow Total discharge of water from a catchment in streamsand rivers.

Sustainable urban Aim to mimic as closely as possible the natural drainage systems drainage of a site to minimise the impact of urban

development on the flooding and pollution ofwaterways.

Transpiration Process whereby water is taken up from the soil bytree roots and evaporated through pores in the leaves.

Turbidity A measure of light intercepted by water due topresence of suspended and dissolved matter andmicro-organisms. Increasing turbidity decreases lightpenetrating the water column. High levels of turbidityharm aquatic life.

Water yield Quantity of water as an output from a catchment,including both groundwater recharge and surfacewater components.

23

40 Fuhrer H.-W. (Ed. 2002) “Wald und Wasser- 30 Jahre forsthydrologische Untersuchungen im KrofdorferForst.” Hessen- Forst FIV, Report No. 29.

41 Gagkas, Z., K. Heal, N. Stuart and T. R. Nisbet (2006) “Forests and water guidelines: broadleaved woodlandsand the protection of freshwaters in acid-sensitive catchments”. Forestry Commission, Edinburgh, 66 pages.

42 Gash, J.H.C. & Stewart, J.B. (1977) “The evaporation from Thetford forest during 1975”. Journal ofHydrology, 35, pp. 385-396.

43 Gill, G. and G. Patterson (no date) “Global Partnership on Forest Landscape Restoration: Investing inPeople and Nature”. Kielder Forest, United Kingdom.

44 Globevnik, L. (2006) “Effects of forest cover change on the runoff regime of the Dragonja River inSlovenia”.Abstract from the scientific forum of the International Congress on Cultivated Forests 3rd-7thOctober 2006, Bilbao, Spain, 65 pages.

45 Green, J. C., I. Reid, I. R. Calder and T. R. Nisbet (2006) “Four-year comparison of water contents beneath agrass ley and a deciduous oak wood overlying Triassic sandstone in lowland England”. Journal of Hydrology,329, pp. 16-25.

46 Hall, R. L. (1994) “Hydrological aspects of broadleaved woodland: Implications for water supply”. Forestsand water: Proceedings of a discussion meeting, Heriot Watt University, Edinburgh. Institute of CharteredForesters, pp. 44-60.

47 Hall, R. L. (2003) “Short rotation coppice for energy production: hydrological guidelines”. DTI New andRenewable Energy Programme: B/CR/00783/GUIDELINES/SRC URN 03/883.

48 Hall, R. L., S. J.Allen, P.T.W. Rosier, D. M. Smith, M. G. Hodnett, J. M. Roberts, R. Hopkins, H. N, Davies, D. G.Kinniburgh and D. C. Goody (1996) “Hydrological effects of short rotation coppice”. Institute of Hydrologyreport to the Energy Technology Support Unit, Institute of Hydrology:Wallingford, UK.

49 Harding, R. J., R. L. Hall, C. Neal, J. M. Roberts, P.T.W. Rosier and D. K. Kinniburgh (1992) “Hydrologicalimpact of broadleaf woodlands: Implications for water use and water quality”. Institute of Hydrology,British Geological Survey Project Report 115/03/ST and 115/04/ST for the National Rivers Authority,Institute of Hydrology:Wallingford, UK.

50 Hardcastle, P. D. Review Team Leader (2005) “A review of the potential impacts of short rotation forestry– final report”. LTS International.

51 Haycock, N. E. and G. Pinay (1993) “Groundwater nitrate dynamics in grass and poplar vegetated riparianbuffer strips during the winter”. Journal of environmental quality, 22, issue 2, pp. 273-278.

52 Haydon, S. R., R. G. Benyon and R. Lewis (1996) “Variation in sapwood area and throughfall with forest agein mountain ash (Eucalyptus regnans F. Muell)”. Journal of Hydrology, 187, pp. 351-366.

53 Howorth, R. and C. Manning (2001) “Land use change and the water environment of the West Wealdlandscape over a 30-year period (1971-2001)”. Report for Sussex Wildlife Trust and the EnvironmentAgency, Sussex area, 34 pages.

54 Hibbert,A. R. (1967) “Forest treatment effects on water yield”. In: Sppoer,W. E. and H.W. Lull (Eds)International Symposium for Hydrology, Pergammon: Oxford, 813 pages.

55 Hughes, F.M.R. (ed.) (2003) “The Flooded Forest: Guidance for policy makers and river managers in Europeon the restoration of floodplain forests”. FLOBAR2, Department of Geography, University of Cambridge,UK. 96 pages.

56 Holman, I.P. and P.J. Loveland (eds.) (2002) “REGIS: Regional Climate Change Impact Response Studies inEast Anglia and North West England”. UK Climate Impacts Programme, Oxford. www.ukcip.org.uk.

57 Hsia,Y. J. and C. C. Koh (1982) “Water yield resulting from clearcutting a small hardwood basin in centralTaiwan”. International Association of Hydrological Sciences Publication, 140, pp. 215-220.

58 Ilstedt, U.,A. Malmer, E.Verbeeten and D. Murdiyarso (2006) “The effect of afforestation on waterinfiltration in the Tropics: a systematic review and meta-analysis”. Oral presentation at the InternationalCongress on Cultivated Forests, 3rd-7th October 2006: Bilbao, Spain.

59 Irvine, J., B. E. Law, M. R. Kurpius, P. M.Anthoni, D. Moore and P. Schwarz (2004) “Age-related changes inecosystem structure and function and effects on water and carbon exchange in ponderosa pine”.TreePhysiology, 24, pp. 753-763.

60 Jackson, R. B., E. G. Jobbagy, R.Avissar, S. B. Roy, D. G. Barrett, C.W. Cook, K.A. Farley, D. C. le Maitre, B.A.McCarl and B. C. Murray (2005) “Trading water for carbon with biological carbon sequestration”. Science,23, 310, pp. 1944-1947.

61 Jacob (2006) “Overview of climate change projections in Europe”. International Workshop on ClimateChange Impacts in the Water Cycle, Resources and Quality. 25-26th September 2006: Brussels, Belgium.

62 Jayasuriya, M. D.A., G. Dunn, R. Benyon and P. J. O’Shaughnessy (1993) “Some factors affecting water yieldfrom mountain ash dominated forests in south-east Australia”. Journal of Hydrology, 150, pp. 345-367.

63 Kirby, K. J., S. M. Smart, H. I. J. Black, R. G. H. Bunce and R. J. Smithers (2005) “Long term ecological changein British woodland (1971-2001).A re-survey and analysis of change based on the 103 sites in the NatureConservancy ‘Bunce 1971’ woodland survey”. English Nature Research Reports number 653, 139 pages.

64 Kitteridge, J. (1948) “Forest Influences”. McGraw-Hill, New York, 394 pages.65 Kuczera, G.A. (1987) “Prediction of water yield reductions following a bushfire in ash-mixed species

eucalypt forest”. Journal of Hydrology, 94, pp. 215-236.66 Link,T. E., M. Unsworth and D. Marks (2004) “The dynamics of rainfall interception by a seasonal temperate

forest”.Agricultural and Forest Meteorology, 124, pp. 171-191.67 Linstead, C. and A.M. Gurnell (1998) “Large woody debris in British headwater rivers. Physical habitat role

and management guidelines”. R&D Technical Report W185. Environment Agency: Bristol, UK.68 Llorens, P. and F. Gallart (2000) “A simplified method for forest water storage capacity measurement”.

Journal of Hydrology, 240, pp. 131-144.69 Lowrance, R., R.Todd, J. Fail, Jr., O. Hendrickson, Jr., R. Leonard and L.Asmussen (1984) “Riparian Forests as

Nutrient Filters in Agricultural Watersheds”. BioScience, 34, pp. 374-377.70 Lynch, J.A., E.S. Corbett and K. Mussallem (1985) “Best management practices for controlling non-point

source pollution on forested watersheds”. Journal of Soil Water Conservation, 40, pp. 87-91.71 McCulloch, J. S. G. and M. Robinson (1993) “History of forest hydrology”. Journal of Hydrology, 150, pp.

189-216.72 Metcalfe, R.A and J. M. Buttle (1999) “Semi-distributed water balance dynamics in a small boreal forest

basin”. Journal of Hydrology, 226, pp. 66-87.73 Mills, D. H. (1980) “The management of forest streams”. Forestry Commission Leaflet no. 78, London:

HMSO.74 Moore, (1999) “Forests, hydrology and water quality: impacts of silvicultural practices”. University of

Florida, Institute of Food and Agricultural Sciences, pp.13. http://edis.ifas.ufl.edu/FR009#disc.75 Neal , C. (2002) “Interception and attenuation of atmospheric pollution in a lowland afforested site, Old

Pond Close, Northamptonshire, UK”. Science of the Total Environment, 282-283, pp. 99-119.76 Neal, C.,A. J. Robson, R. L. Hall, G. Ryland,T. Conway and M. Neal (1991) “Hydrological impacts of

hardwood plantation in lowland Britain: preliminary findings on interception at a forest edge”. Journal ofHydrology, 127, pp. 349-365.

77 Neal, C. and B. Reynolds (1998) “The impact of conifer harvesting and replanting on upland water quality”.EA R&D Technical Report P211, Environment Agency: Bristol.

78 NEGTAP (2001) “National Expert Group on Transboundary Air Pollution:Acidification, Eutrophication andGround Level Ozone in the UK.” 1st report. On behalf of the UK Department of the Environment,Transport and the regions and the devolved administrations. www.nbu.ac.uk/negtap/finalreport.htm.

79 NERC (1975) “The flood studies report, 4”. Natural Environment and Research Council, London.80 Newson, M. D. and I. R. Calder (1989) “Forests and water resources: problems of prediction on a regional

scale”. Philosophical Transactions of the Royal Society of London, 324, pp. 283-298.81 Nisbet,T.R. (2001) “The role of forest management in controlling diffuse pollution in UK forestry”. Forest

Ecology and Management, 143, pp. 215-226.82 Nisbet,T.R. (2002) “Implications of climate change: soil and water”. In: Broadmeadow, M. (ed) “Climate

change: impacts on UK forests”, Forestry Commission Bulletin 125, pp 53-67. Forestry Commission,Edinburgh

83 Nisbet,T.R. (2005) “Water use by trees”. Information note for the Forestry Commission, 8 pages.84 Nisbet,T. R., H. Orr and S. Broadmeadow (2004) “A guide to using woodland for sediment control”. Forest

Research, 6 pages.85. Nisbet,T. R. and H.Thomas (2006) “The role of woodland in flood control: a landscape perspective”. In:

Davies, B.R. & S.Thompson (eds) “Water and the Landscape:The Landscape Ecology of FreshwaterEcosystems”, Proceedings of the fourteenth annual IALE(UK) conference, International Association ofLandscape Ecology (UK), pp. 118-125.

86 Nisbet,T. R. and J.S. Stonnard (1995) “The impact of forestry on low flow regime - an analysis of long-termstreamflow records from upland catchments.” In: Black,A.R. and R.C. Johnson (eds) “Proceedings of theFifth National Hydrological Symposium”, Institute of Hydrology:Wallingford, OXON, pp 7.25-7.30.

87 Nunez, D., L. Nahuelhaul and C. Oyarzun (2006) “Forests and water: the value of native temperate forestsin supplying water for human consumption”. Ecological Economics, 58, pp. 606-616.

88 O’Connell, P. E., K. J. Bevan, J. N. Carney, R. O. Clements, J. Ewen, H. Fowler, G. L. Harris, J. Hollis, J. Morris,G. M. O’Donnell, J. C. Packman,A. Parkin, P. F. Quinn, S. C. Rose, M. Shephard and S.Tellier (2004) “ProjectFD214: Review of impacts of rural land use and management on flood generation”. Defra R&D TechnicalReport FD2114. Defra: London.

89 Penman, H. L. (1948) “Natural Evaporation from Open Water, Bare Soil and Grass”. Proceedings of theRoyal Society of London. Series A, Mathematical and Physical Sciences, 193, pp. 120-145.

90 Pizarro, R., S.Araya, C. Jordan, C. Farias, J. P. Flores and P. B, Bro (2006) “The effects of changes in vegetativecover on river flows in the Purapel river basin in central Chile”. Journal of Hydrology, 327, pp. 249-257.

91 Pinay, G., L. Roques and A. Fabre (1993) “Spatial and Temporal Patterns of Denitrification in a RiparianForest”. Journal of Applied Ecology, 30, issue 4, pp. 581-591.

92 Postel, S. L. (2000) “Entering an era of water scarcity: the challenges ahead”. Ecological Applications, 10 (4),pp. 941-948.

93 Price (2005) “Loch Katrine: Land use change impacts to yield”, contract report from Jacobs Babtie toScottish Water.

94 Puplett, D. (2003) “Riparian Woodlands”.Trees for Life newsletter, Caledonia Wild! Summer 2003,http://www.treesforlife.org.uk/forest/ecological/riparianwoodland.

95 Putuhena,W. M. and I Cordery (2000) “Some hydrological effects of changing forest cover from eucalyptsto Pinus radiata”.Agricultural and Forest Meteorology, 100, pp. 59-72.

96 Rackham, O. (2006) “Woodlands”. Collins New Naturalists Series.97 Rakhmanov ,V.V. (1962) “Role of forests in water conservation”. Israel Program for Scientific Translations,

Jerusalem, 1966, 192 pages.98 Rice,T. (2005) “Sustainable forestry in the UK”. Friends of the Earth’s Paper to the Government Panel on

Sustainable Development – Forests.http://www.foe.co.uk/resource/consultation_responses/sustainable_forestry_uk.html on 10/10/2006.

99 Roberts, J. M. (1983) “Forest transpiration: a conservative hydrological process?” Journal of Hydrology, 66,pp. 229-245.

100 Roberts, J. M. and P.T.W. Rosier (1994) “Comparative estimates of transpiration of ash and beech forest ata chalk site in southern Britain”. Journal of Hydrology, 162, pp. 229-245.

101 Roberts, J. M. and P.T.W. Rosier (2005) “The impact of broadleaved woodland on water resources inlowland UK: III.The results from Black Wood and Bridgets Farm compared with those from otherwoodland and grassland sites”. Hydrology and Earth System Sciences, 9, issue 6, pp. 614-620.

102 Roberts, S., R.Vertessy and R. Grayson (2001) “Transpiration from Eucalyptus sieberi (L. Johnson) forests ofa different age”. Forest Ecology and Management, 143, pp. 153-161.

103 Robinson, M.,A. L. Cognard-Planq, C. Cosandey, J. David, P. Durand, H.W. Fuhreer, R. Hall, M. O. Hendriques,V. Marc, R. McCarthy, M. McDonnell, C. Martin,T. Nisbet, P. O. O’Dea, M. Rogers and A. Zollner (2003)“Studies of the impacts of forests on peak flows and baseflows: a European perspective”. Forest Ecologyand Management, 186, pp. 85-97.

104 Robinson, M. and A. Dupeyrat (2003) “Effects of commercial forest felling on streamflow regimes atPlynlimon, mid-Wales”. Hydrological Processes, 19, pp. 1213-1226.

105 Rutter,A. J. (1963) “Studies in the water relations of Pinus sylvestris in plantation conditions, I.Measurements of rainfall and interception”. Journal of Ecology, 51, pp. 191-203.

106 Scott, D. F., E. Prinsloo and G. Moses (2006) “The long-term effects of Pine and Eucalypt plantations onstreamflow, and a possible link to site productivity”. Extended Abstracts from the Conference on Forestsand Water in a Changing Environment, Beijing, China,August 2006.

107 Scottish Native Woods (1996) “Restoring and managing riparian woodlands” Scottish Native WoodsBooklet.

108 Stanley, B. and P.A.Arp (2002) “Effects of forest harvesting on basin-wide water yield in relation to thepercentage of watershed cut: a review of literature”. Nexfor / Bowater Forest Watershed ResearchCentre, Faculty of Forestry and Environmental Management UNB, Fredericton, NB, 35 pages.

109 Sun, G., G. Zhou, Z. Zhang, X.Wei, S. G. McNulty and J. M.Vose (2006) “Potential water yield reduction dueto forestation across China”. Journal of Hydrology, 328, pp. 548-558.

110 Sutton, M.A, D. Fowler and J.B. Moncrieff (1993) “Exchange of atmospheric ammonia with vegetationsurfaces. I. Unfertilised vegetation”. Quarterly Journal of Royal Meteorological Society, 119, pp. 1023-1045.

111 Swaine, M. D., J.Adomako, G.Ameka, K.A.Ade Graft-Johnston and M. Cheek (2006) “Forest river plants andwater quality in Ghana”.Aquatic Botany, 85, Issue 4, pp. 299-308.

112 Thomas, H. and T. Nisbet (2006) “An assessment of the impact of floodplain woodland on flood flows”.Water and Environment Journal, pp. 1747-6585.

113 Thompson, R., J. Humphrey, R. Harmer and R. Ferris (2003) “Restoration of native woodland on ancientwoodland sites”. Forestry Commission practice guide, 52 pages.

114 UNECE (2006) “Payments for ecosystem services in integrated water resources management”. Fourthmeeting Bonn (Germany), 20–22 November 2006. Item 6 (b) of the provisional agenda.

115 Viramontes, D. and L. Descroix (2003) “Changes in the surface water hydrologic characteristics of anendoreic basin of northern Mexico from 1970 to 1998”. Hydrological Processes, 17, pp. 1291-1306.

116 Wakeel,A., K. S. Rao, R. K. Maikhuri and K. G. Saxena (2005) “Forest management and land use/coverchanges in a typical micro watershed in the mid elevation zone of Central Himalaya, India”. Forest Ecologyand Management, 213, pp. 229-242.

117 Watson, F. G. R., R.A.Vertessy and R. B. Grayson (1997) “Large scale, long term, physically based predictionof water yield in forested catchments”. Proceedings, International Congress on Modelling and Simulation(MODSIM 97): Hobart,Tasmania, 8-11 December, pp. 397-402.

118 Webber, J., J.N. Gibbs and S. Hendry (2004) “Phytophthora disease of alder”. Forestry CommissionInformation Note 6 (Third edition), 6 pages.

119 Wei, X., and G.W. Davidson (1998) “Impacts of large scale timber harvesting on the hydrology of theBowron River Watershed”. Published in the Proceedings of “Mountain to Sea: Human interaction with thehydrological cycle” Canadian Water Resource Association 51st National Conference in Victoria, June 10-12th, pp. 45-52.

120 Williams,A. G., M. Kent and T. L. Kernan (1987) “Quantity and quality of bracken throughfall, stemflow andlitterflow in a Dartmoor catchment”. Journal of Applied Ecology, 24, pp. 217-230.

121 Wullschleger, S. D., K. B.Wilson and P. J Hanson (2000) “Environmental control of whole-planttranspiration, canopy conductance and estimates of the decoupling co-efficient for large red maple trees”.Agricultural and Forest Meteorology, 104, pp. 157-168.

122 Zhou, M. C., H. Ishidaira, H. P. Hapuarachchi, J. Magome,A. S. Kiem and K.Takeuchi (2006) “Estimatingpotential evapotranspiration using Shuttleworth–Wallace model and NOAA-AVHRR NDVI data to feed adistributed hydrological model over the Mekong River basin”. Journal of Hydrology, 327, pp. 151-173.

123 Zon, R. (1927) “Forests and Water in the Light of Scientific Investigation”. U.S. Department of Agriculture,Government Printing Office:Washington D. C. 106, 1927 pages.

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