Post on 18-Dec-2015
transcript
EU Life-Environment funded project:
Re-creating woodland and heathland on slate waste in Wales
J C Williamson, E C Rowe, J R Healey, D L Jones,
P J Holliman, M A Nason
Partners: University of Wales, Bangor; Alfred McAlpine Slate; Slate Ecology Co., Pizarras-Villar del Rey
Output: Science-based guide to Best Practice for achieving the restoration of self-sustaining, semi-natural ecosystems of high conservation value
Context of the Restoration project at Penrhyn Quarry
where penrhyn lies in relation to SNPA and SSS1
conditions prog, heath, woodl
Structure of presentation
1. Broadleaf woodland creation- tree performance- soil performance
2. Heathland creation
3. Fertilizing naturally established vegetation- tree performance- invertebrate abundance and diversity
4. Bird abundance and diversity
5. Detritivore abundance and diversity
Broadleaf Woodland Creation
Aims - Tree performance To examine the effects on tree establishment and growth of improved
• water supply• nutrient supply
To assess requirements of different tree species in relation to their
• ability to fix nitrogen• seed size
Broadleaf Woodland Creation
Aims - Soil performance
• Typically, quarry sites lack topsoil, so need to design substrates for nutrient and water delivery
• Nutrient cycling needs a ‘kick start’, so need organic matter
• Develop soil biochemical predictors of longer-term above-ground success - compare planted and natural systems
Design: 3-way split-plot factorial
Main plots: 3 water-holding treatments (x 3 reps)None Clay Polyacrylamide gel
Split plots: 5 “tree” speciesAlder Birch Gorse
Oak Rowan (i.e. 2 N-fixers, 4 non-fixers; 2 small-seeded, 3 large)
x 3 nutrient supply treatmentsNone Biosolids+ Mineral NPK+trace
paper sludge slow release 15:10:10in 2 randomised complete blocksSheltered, 275 m a.s.l. Exposed, 330 m a.s.l.
Method
• Set up April 2000
• Flat areas of slate waste fenced against sheep
• Tree species planted as nursery-raised 1 year old
seedlings
• Standard 3 L hole dug for all treatments
• 5 plants per plot, in quinqunx arrangement (50 cm
spacing)
Method used for tree planting
Slates arranged tocollect rainfall
1-year oldtransplant
Soil amendments in 3 L pocket, depth 15 cm
Free-drainingcoarse slate waste
1mRoots moving towards fines
Water-holding fines
Species Alder Birch Gorse Oak Rowan
Seed size small small large large large
N2 fixer yes no yes no no
Fertilizertreatment
Basal area (mm2) Mean
No fertilizer44 5 33 6 5 19 a†
NPK 52 26 50 11 28 33 b
Biosolid-
paper mix
70 41 59 10 37 43 c
Mean 55 c 24 b 47 c 9 a 23 b 32
Results: Fertilizer effects on stem basal area after 18 months
† Main effects labeled with same letter were not significantly different (P<0.05)
Species Alder Birch Gorse Oak Rowan
Water-holdingtreatment
Basal area (mm2) Mean
No treatment 42 21 44 8 1827 a†
Boulder clay 74 33 59 11 32 42 b
PAM gel 49 18 38 8 20 27 a
Mean 55 c 24 b 47 c 9 a 23 b 32
† Main effects labeled with same letter were not significantly different (P<0.05)
Results: Water-holding effects on stem basal area after 18 months
Results: Fertilizer effects on selected soil quality predictors after 18 months
Fertilizer treatment P
value
Semi-
natural
woodland
No
fertilizer
Biosolids-
paper mix
NPK
Microbial biomassmg N kg-1
21 a† 135 b 29 a < .001 137 b
Respirationmg C kg-1.h-1
0.40 a 3.29 b 0.44 a < .001 2.63 b
Microbial diversity(Simpson's Index 1/D)
4.3 a 6.8 b 5.3 a 0.036 7.2 b
† Main effects labeled with same letter were not significantly different (P<0.05)
Conclusions - Tree performance
• N-fixers establish rapidly on slate waste even without added fertilizer
• Small-seeded tree species responded more than large-seeded species to fertilization
• Organic amendment resulted in greater tree growth than mineral NPK
• Polyacrylamide gel appears to be of little benefit
• Boulder clay greatly improved tree growth
Conclusions - Soil performance
• Organic matter (OM) addition increased soil microbial biomass, respiration and diversity, and therefore nutrient cycling, relative to other treatments
• NPK did not improve soil quality, compared with unamended slate
• Within 18 months, soil quality predictors in the OM amended treatment were similar to those of nearby semi-natural woodland soil
• Biosolid-paper mix was a very effective surrogate
Heathland creation
Three approaches were tested:
• Direct transfer of heathland turf
• Planting heather plugs
• Seeding using harvested heather sprigs or seed heads
Transferring heathland turf
Age (years)
Co
ver
(%)
0
25
50
75
100
125
150
175
200
225
250
275
Ericoids (e.g. heather)Graminoids (e.g. soft rush)
TARGETS TRIALS ----------------------------------->Semi-natural
heath
Old tip heath
14000(?) c.85 1 2 3 1 2 3 1 2 3 1 2 3
Not fenced
Heatherplanted
Not fenced
Heathtopsoilapplied
Sheepexcluded
Heathtopsoilapplied
Sheepand rabbitsexcluded
Heathtopsoilapplied
Ericoid cover required for Phase 1 "Heath"
Results: planting plugs and heathland turf transfer
Seeding heathland species
• Necessary when creating large areas
• Ericoids naturally establish on slate fines and clay
Trials• dried chopped ericoid sprigs applied to clay ± bark peelings as mulch (Nov 2000, Feb 2001)
• fresh seed capsules with tackifier and geotextile mulch (Nov 2001)
• dried and ‘smoked’ seed capsules with tackifier and geotextile mulch (May 2002)
Results: Heather seeding
• Seedling survival low 1-6 m-2
• Bark mulch had no effect
• Application rate had no effect (0.2 vs. 0.6 kg m-2)
• Applying fresh seed capsules with geotextile mulch did not improve survival
• Too early to say if ‘smoking’ has helped
• Good germination in seed trays
Conclusions
• Planting heather gives no advantage over spreading heathland turf
• Excluding sheep speeds the establishment of heather cover and the development of a community similar to NVC H10a (target)
• Excluding rabbits results in excessive growth of graminoids and a floristic trajectory diverging from target heathland
• Grasses may be important to early heather survival
Fertilizer addition to naturally established trees
To test if: • Revegetation can be accelerated
• Leaf invertebrate abundance and diversity can be enhanced
• Other environmental factors influence invertebrate communities
Experimental set-up
10 fert. 10 un fert.
20 birch(10 pairs )
10 fert. 10 un fert.
20 w illow(10 pairs )
40 quarry trees
10 un fert.
10 birch
10 un fert.
10 w illow
20 woodland trees
60 trees
NPK fertilizer (15:10:10) added at 175 kg N/ha/y for 2 y
Tree response to fertilization
Mean shootextension, cm
Birch Willow
Unfertilized 12.9 (1.8) 11.6 (2.4)
Fertilized 21.2 (2.0) 20.0 (2.3)
P (Paired T-test) <0.001 < 0.05
Leaf invertebrate abundance and diversity
0
0.1
0.2
0.3
0.4
May June July
Month
Men
hin
ick'
s In
dex
V
alu
e
Q
QF
W
0
0.002
0.004
0.006
0.008
0.01
0.012
0.014
0.016
May June July
Month
No.
aphi
ds p
er c
m fo
liage
W
Q
QF
• Aphid abundance responded to fertilization in July 2000 and in May-July 2001
• In 2001, species richness was reduced by fertilization
• Less mobile groups such as Lepidoptera did not respond to fertilization and isolation distance was important
2000
2001
•Total bird species, but notably passerines, were fewer in the quarry compared to adjacent semi-natural habitats
•Total number of detections and species richness significantly increased with age of slate waste tip (25 - 85 y)
• In the quarry, %tree cover was very important toredstarts (r +0.47), agood indicator spp.
Bird Survey - Point Sampling
Redstart (Phoenicurus phoenicurus)
Invertebrates - Litter bag sampling
• Total numbers in the quarry were 50% less than in adjacent semi-natural habitats
• Species richness was positively correlated with quarry tree diversity and % cover of vegetation, ericoids and mosses
• Acarina (mites) numbers were the most sensitive to% tree cover (r +0.47), agood indicator group
Acarus spp.
Overall Conclusions
• Woodland establishment was enhanced by organic fertilizer produced from locally available, free wastes
• In situ boulder clay subsoil was necessary as a water-holding treatment for trees and freely available
• Heathland creation by direct transfer of turf was successful
• Low-cost heathland creation by seeding was problematic. A nurse grass may improve success