Date post: | 24-May-2015 |
Category: |
Technology |
Upload: | inaziomaria |
View: | 190 times |
Download: | 0 times |
The effect of mechanical site preparation on water and soil
protection in radiata pine plantations in the Basque Country
Nahia Gartzia Bengoetxea
Inazio Martínez de Arano
Ander Gonzalez Arias
Goods and servicesprovided by forest in relation to soil function
• Maintain or restore productivity
• Protect other ecosystem compartments- Carbon sequestration- water quality/quantity
Sediment outputs
• Preserve soil ecosystem integrity
Starting Point
Forest play an important role in the protective functions of soil and water quality
• Forest cover disappears• Understory and litter removals• Soil disturbance (logging, traffic, site preparation)
Main difference between (commercial) Plantations & other Forests is the Inter-Rotation period.
Starting Point
time gap between harvest and the crown closure of the next rotation (Mead 1990).
Pinus radiata
High slopes increase disturbance risk
Starting Point
Mechanized operations have increased Since 1980s Are common on slopes under 40%
Physical damage linked to machinery use in harvest, logging and soil preparation operations is one of the key factors of forest soil sustainability (Constantini et al. 1997 Aust. For. 60/4 )
Objective
To describe the effect of commercial site preparation on productivity, soil properties and sediment exports.
To evaluate sustainability and the production of goods and services in relation to soil & water conservation
TRIAL DESIGN
4 site preparation industrial treatmentsManual ScalpingRippingDiscontinuous ripping
3 repetitions
3.3 ha30% slope
Para ver esta película, debedisponer de QuickTime™ y deun descompresor TIFF (LZW).
90
70
50
30
10
10
30
50
70
90
5 15 25 35 45 55 65 75
Bloque inferior
90
70
50
30
10
10
30
50
70
90
5 15 25 35 45 55 65 75
Bloque medio
90
70
50
30
10
10
30
50
70
90
Bloque superior
5 15 25 35 45 55 65 75
Soil depth before site preparation
Soil depth
pH M.O (%)
N (%)
C/N P (mg kg-1)
Ca meq/100
Mg meq/100
K (mg kg-1)
A 5.68 3.26 0.18 10.34 1.07 8.00 0.69 92.33
Bw1 5.79 1.42 0.12 6.67 0.04 6.92 0.72 51.33
Bw2 6.75 0.80 0.11 4.21 0.09 14.65 0.74 39.00
1
Soil chemical properties before site preparation
0102030405060708090100
(i) Manual (M): Clearing harvest residues and existing vegetation by hand; planting holes were also manually made
(ii) Scalping (S): Harvest residues and existing vegetation were cleared with the front blade of a bulldozer and planting holes were done by hand
(iii) Ripping (R): Harvest residues and vegetation was cleared as in the S treatment and afterwards a ripper that dug a 40-50 cm deep trench in the line of maximum slope was used to facilitate plantation that was also made by hand
Site preparations:
Manual Scalping
Ripping
before site preparation
after site preparation
Soil fertility:
OM, total N, C/N, pH, Ca, Mg, K, CEC, P-Olsen
Soil Organic Matter dynamics:
In situ seasonal N mineralization over 1 year
Tree growth evolution:
All trees were measured twice per year from 2002 to 2005
Soil Erosion:
At all Plots, 1.4 m long, 40 cm deep and 40 cm wide ditch was established to monitor soil loss and sediments were recovered once per year. years yr 1-3
Soil Physics:
Resistance to penetration, bulk density, saturated hydraulic conductivity, water holding capacity at -33 KPa and -1500 Kpa yr2-tr4
Water run-off:
water volume (ml) was determined over 1 year in1 m2 run-off plots yr-1
1300 mm
500 mm
15 mm
RESULTS
No difference in height between manual and rippingScalping clearly behind in first 4 years
20% loss in productivity?
* differences in diameter are non significant
Productivity
0
20
40
60
80
100
120
140
160
180
200
ener-02
juni-02 novi-02
abri-03 sept-03
febr-04 juli-04 dici-04 mayo-05
octu-05
marz-06
Manual Scalping Ripping Dis. Ripping
• 36% of soil carbon loss (1st year)• C/N shows top soil removal
Soil Carbon
0,51
1,52
2,5
33,5
44,5
55,5
C org(%)4
6
8
10
12
14
16
18
20
22
C/N
subsolado
roza al aire
manual
FORSEE Project
Changes in aggregate size distribution mayProduce long term changes in soil carbondynamics
40 yr old radiata stand Adjacent mechanized 1 yr old stand
-2
0
2
4
6
8
10
12
P-Olsen(mg/kg)
subsolado
roza al aire
manual
Box PlotSplit By: treatment
Soil Chemistry
Olsen P ppmmuy bajo
bajo
adecuado
Nitrógeno Fósforo
Calcio
Cobre
magnesio
Potasio Azufre ing.
n=187 rodalesDiagnóstico según Will (1985)
• P is the most liming element in radiata pine plantations
Soil Chemistry
Manual Scalping rippingmean cv mean cv mean cv
N total 0,2 21% 0,15 26% 0,121 30%C/N 15,4 17% 12,4 23% 10,7 28%P-Olsen(mg/kg) 2,2 82% 1,1 82% 0,7 171%Ca (mg/kg) 1129,5 47% 2354,7 61% 1224,2 99%Mg (mg/kg) 103,5 24% 70,4 63% 66 68%K (mg/kg) 80,0 63% 50,3 58% 40,1 45%
a b c
a b c
a b c
a b a
a b b
a b b
For all treatments, nutrient contents are not outside of normal radiata pine soils in the Basque Country
In situ N mineralization. 1st year after soil preparation
0
5
10
15
20
25
30
autumn spring summer winterCell
subsolado
roza al aire
manual
Interaction Line Plot for N-NH4+(mg/kg)Effect: season * treatment
* Values are means with standard errors in parentheses. Within each column, significantly different treatment means based on one-way analysis of variance and Bonferroni/Dunn test are indicated by different lowercase letter
Bulk density (Mg m-3)
Soil Penetration Resistance
(MPa)
Moisture capacity
-0.033 MPa (%)
Moisture capacity -1.5 MPa
(%)
Saturated hydraulic conductivity
(cm h-1)
Manual 1.25 (0.0)a* 1.63 (0.48)a 36.30 (0.82)a 18.41 (3.08)a 3.79 (0.14)a
Scalping 1.50 (0.0)b 3.73 (0.89)b 32.83 (0.37)b 15.93 (0.79)a 0.46 (0.17)b
Ripping 1.49 (0.81)b 3.23 (0.51)b 31.02 (0.48)c 15.64 (0.60)a 0.98 (0.36)b
1
Soil Physical Properties yr 1
• 20% increase in Bulk density• x 2.5 increase in soil penetration resistance (10 cm)• Reduction to 26%-12% in Hydraulic conductivity• 12%-15% loss in water holding capacity
0
5
10
15
20
25
30
autumn spring summer winterCell
subsolado
roza al aire
manual
• Soil moisture at root depth (yr 1) is afected• ripping treatment maintains more moisture in summer
a
a
b
bab
b
b
a
Runoff during year 1Water collected after every significant rain event
• x 3 increase in runoff on bladed• x 2 increase in runoff in ripped treatment
Soil Erosion yr 1-3
* Soil loss in kg/ha at constant weight
Mean erosion
Tons yr-1 ha-1
Management
induced
manual 0.018
scalping 1.105 X 60
ripping 1.642 X 89
Autumn 2002 Spring 2003 Autumn 2003 Autumn 2004Manual 26* 0 0 11Scalping 389 1031 631 162Ripping 423 1273 1136 457Disc. Ripping 369 723 2355 701
soil strenght first 30 cm
0
1000
2000
3000
4000
5000
6000
7000
Manual Roza Subsol Discon Subsolado
kg / cm2
Behekoaerdikoagoikoa
• 12%-26% increase in soil strength
Soil Strength yr 4
a b
0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
max30
Subsolado
Subsol Discon
Roza
Manual
Conclusions
• Mechanized site preparation has produced a significativeRemoval of topsoil, organic matter and nutrients
• Soil compactation and deterioration of hydraulic propertiesare limiting growth in the scalping treatment
• Ripping has alleviated compactation and improvedwater availability in the dry season.
• Deterioration of soil physical properties is severe andShows no recovery in the sort term (4 years).
• Sustained productivity cannot be the only criteria for Forest Soil sustainability
Two treatments show similar productivity butthey differ in:
+ x 80 sediment exports- x 2 in hydraulic conductivity- 35% in carbon stock- 15% in Water holding capacity- 20% in bulk density
• Genetically improved material and proper fertilizationCould mask observed differences in subsequent rotations
• Relevant in the long term?• Relevant at the land scape?
One treatment minimizes soil disturbance, produces very lowSediment exports, maintains carbon stocks with no penalty in productivity.
The good news!
Also it must be considered that there soil treatment is no homegeneous.
Finally,
Plantation Forestry may provide good and services in relationto soil, carbon and water conservation, but it may not.
Management at the interotation period is critical in this respect