WP coordinator meeting June 17/18 2010

WP3 progress report

Reference Land-use transitions

Response variable or main effect

Stratification or main contrast

Number of observations and studies

Main conclusions

Allen, 1985 forest to cropped, grazed or plantation

difference soil C %, weighted by sample size

temperate versus tropical, split soils into ´young´or ´old´ categories based on soil order

26 studies;205 paired comparisons

Magnitude of soil C losses vary geographically: losses were 50% greater on highly weathered tropical soils compared to younger soils in the tropics, or similar soils in the temperate zone

Mann, 1986 uncultivated to cultivated

regression of carbon content in cultivated soils on carbon content in paired uncultivated soils; analyzed both C% and samples adjusted to fixed depth

depth, soil orders and suborders

50 studies; 625 paired comparisons;estimated BD when lacking

Average losses for 0-15 cm are 20% and from depths from 0-30cm lose less than 20% with cultivation

Detwiler, 1986

forest to cultivated land, forest to pasture, and secondary forest

Change in percentage soil C (%); C= 100-((%Ct/%Co)*100)Where Ct = %C at some time t, and Co = unmanaged C %

Uncultivated soil C stocks are based on aggregated life zone estimates; land-use change effects are not partitioned geographically

28 studies, 128 observations

Fit spline models to change in %C over time for three land-use transitions. Forest to agriculture reduced C% by 40% in 5 years post-clearing, then reached new equilibrium (model explains 20.4% of variance). Forest to pasture reduces C% by 20%, which does not vary with pasture age. Shifting cultivation causes losses of 18-27% of C%.

Davidson & Ackerly, 1993

uncultivated to cultivated

percent change in C stock, (Xc-Xr)/(Xr)*100

Split data into fixed depth versus genetic horizon sampling schemes, analyzed depths separately

18 studies;56 paired comparisons; excluded studies without BD

27.2% (±2.9 SE) loss across all depths (range for subsets was 24 to 43%), losses decrease with depth; carbon losses are not proportional to initial C stocks; no apparent effect of clay%; rates of loss are greatest earliest post-conversion, but decrease with cultivation time.

McGrath et al 2001

primary forest, secondary forest, pasture, annual crops, plantations

ANOVA to test for differences in C% and stocks by land use

Restricted studies to Oxisols or Ultisols

39 studies; 71 plots No differences in soil C concentrations or stocks among land uses

Fearnside & Barbosa, 1998

forest to pasture in Brazilian Amazon

percent change in C stock, (Xc-Xr)/(Xr)*100

“typical” (no input) compared to “ideal” pasture management

7 studies; 10 observations; applied average changes in BD from 5 studies to correct for compaction

typical management reduces soil C by 17.8% (0-20 cm), while “ideal” management increases soil C by 15.0% (0-20 cm)

Paul et al 2002 afforestation absolute and percent change weighted by plantation age

age, type of study, site preparation, prior land use, climatic zone, clay content, and plantation species

43 studies; 204 observations; estimated BD when lacking

Age dependent decrease then increase in soil C stocks, which depended on depth; soil C decreased on sites converted from pasture, and increased on sites converted from cropping; higher rates of accumulation in tropical compared to temperature climates; Pinus species decreased soil C while other species increased it

Murty et al 2002

forest to cultivation; forest to pasture

percent change in C stock, (Xc-Xr)/(Xr)*100

54 studies; 216 observations; restricted studies to ≥ yrs in current land use; used studies with BD, and adjusted data to common mass when possible

22.1%±4.1% (SE) loss in soil C stock with conversion of forest to cultivated lands (BD-corrected data only); no significant change with forest to pasture, 6.4±7.0% increase (BD-corrected data only)

Guo & Gifford, 2002

forest to pasture; pasture to secondary forest; pasture to plantation; forest to plantation; forest to crop; crop to plantation; crop to secondary forest; pasture to crop; crop to pasture

ln(Xc/Xr); unweighted meta-analysis

Analyzed various subsets of the data to look for effects of precipitation, depth, plantation species, and age effects

74 studies; 537 observations; estimated BD when lacking

Increases or decreases depended on land use: forest to pasture conversion increases SOC by 8% (most of this was due to high sequestration rates in areas with rainfall 2000-3000 mm, which had 24% increase (18 to 30 CI)); pasture or forest to plantation decreased soil C, while converting cropped lands to plantations, secondary forests or pastures increased soil C

Reference Land-use transitions Response variable or main effect

Stratification or main contrast

Number of observations and studies

Main conclusions

Silver et al 2004 tropical secondary succession and tree plantations

regressed soil C stocks on stand age

previous land use and life zones : dry (<1000mm), moist (1,000-2,500mm), or wet (>2,500mm)

16 studies; 68 data points (not paired); adjusted data to common depth via regression equations

soil C increased with secondary forest age; rates of increase depended on prior land use, but varied little among life zones

Berthrong et al, 2009 afforestation, i.e. tree plantations established on former grasslands, pastures or agricultural lands

ln(Xc/Xr); unweighted meta-analysis

Species (pine, eucalypt) or other

71 studies; 153 pairs; estimated BD when lacking

‘Afforestation with Pinus decreased soil C stocks by 15%´; this was the only significant result for C

Laganiere et al, 2010 afforestation, percent change in C stock, (Xc-Xr)/(Xr)*100; weighted responses by sample size

By inclusion of organic layer, study design, plantation age, and soil size fraction, previous land use, climatic zone, clay content (above or below 33%), pH, tree species, site preparation

33 studies;200 observations excluded studies without BD

Increases in C stocks following afforestation depended on previous land use :26% increase for crop land, 3% for pastures (NS), and <10% for natural grasslands (NS)

Reference Land-use transitions

Response variable or main effect

Stratification or main contrast

Number of observations and studies

Main conclusions

Original 500 papers → 150 paper

Selection criteria:

-Only when carbon stocks were reported (bulk density !!)-Omit plots without obvious or logical reference sites-Only studies that reported data from reference land use that preceded current land use-If multiple paper on same sites: only one included-Studies excluded if plots in different land uses were sampled at diferent depths

-Final database: 92 studies with 974 paired observations.

Land-use transition Depth % Change Log ratio

Mean 95%CI Mean 95% CI

forest to crop (107) All -19.72 -25.67 to -13.43 -0.295 -0.369 to -0.222

forest to pasture (289) 7.21 4.01 to 10.37 0.036 0.006 to 0.066

forest to plantation (69) -6.11 -16.63 to 5.62 -0.154 -0.249 to -0.058

SC: forest to crop (54) -12.61 -18.13 to -6.97 -0.168 -0.242 to -0.099

SC: crop to forest fallow (26) 6.46 -0.07 to 13.28 0.049 -0.014 to 0.112

crop to pasture (7) 8.64 -2.11 to 19.15 0.073 -0.033 to 0.168

crop to plantation (48) 20.59 10.38 to 32.68 0.146 0.071 to 0.227

crop to secondary forest (26) 43.21 22.56 to 66.69 0.292 0.16 to 0.431

pasture to plantation (89) 8.20 2.83 to 13.52 0.050 -0.001 to 0.101

pasture to secondary forest (165)

11.54 6.94 to 16.43 0.074 0.032 to 0.115

forest to crop (32) 0-10 cm -29.36 -36.91 to -20.75 -0.398 -0.512 to -0.288

forest to pasture (98) 15.32 9.65 to 21.11 0.111 0.059 to 0.161

forest to plantation (13) -8.32 -22.35 to 4.316 -0.132 -0.321 to 0.023

SC: forest to crop (7) -10.96 -34.20 to 10.52 -0.187 -0.495 to 0.077

crop to plantation (17) 28.45 6.58 to 58.08 0.185 0.033 to 0.356

crop to secondary forest (11) 11.01 -0.95 to 22.92 0.087 -0.035 to 0.192

pasture to plantation (25) 4.62 -3.89 to 13.53 0.024 -0.057 to 0.104

pasture to secondary forest (18) 15.99 4.84 to 26.81 0.125 0.017 to 0.222

savanna to crop (7) -4.80 -12.38 to 2.81 -0.055 -0.142 to 0.027

savanna to plantation (7) -3.68 -18.75 to 8.61 -0.061 -0.256 to 0.082

Land-use transition Depth % Change Log ratio

Mean 95%CI Mean 95% CI

forest to crop (5) 0-100 cm -23.06 -48.23 to 7.73 -0.357 -0.721 to 0.002

forest to pasture (5) 10.11 -9.74 to 26.38 0.077 -0.126 to 0.234

forest to plantation (11) -10.70 -27.97 to 10.02 -0.171 -0.355 to 0.031

pasture to secondary forest (5) 9.90 -5.85 to 26.56 0.080 -0.061 to 0.225

savanna to crop (5) -15.06 -19.62 to -11.21 0.165 -0.222 to -0.116

Land-use transition Depth % Change Log ratio

Mean 95%CI Mean 95% CI

forest to pasture (0-30 cm)

< 4 yrs (N=20)

5-9 yrs (N=27)

10-19 yrs (N=32)

20-39 yrs (N=32)

> 40 yrs (N=14)

< 1500 mm (N=6)

1501-2000 mm (N=30)

2001-2500 mm (N=60)

2501-3500 mm (N=20)

>3500 (N=18)

low activity clay (N=106)

high activity clay (N=15)

allophanic (N=15)

pasture to secondary forest (0-30 cm)

5-9 yrs (N=9)

10-19 yrs (N=33)

20-39 yrs (N=12)

> 40 yrs (N=5)

1501-2000 mm (N=14)

2001-2500 mm (N=13)

2501-3500 mm (N=23)

>3500 (N=7)

low activity clay (N=21)

high activity clay (N=28)

allophanic (N=12)

forest to pasture (0-10 cm)

< 4 yrs (N=16)

5-9 yrs (N=18)

10-19 yrs (N=25)

20-39 yrs (N=25)

> 40 yrs (N=7)

< 1500 mm (N=5)

1501-2000 mm (N=27)

2001-2500 mm (N=36)

2501-3500 mm (N=13)

>3500 (N=17)

low activity clay (N=76)

high activity clay (N=12)

allophanic (N=9)

forest to pasture (10-50 cm)

1501-2000 mm (N=13)

2001-2500 mm (N=12

2501-3500 mm (N=24)

>3500 (N=40)

low activity clay (N=70)

allophanic (N=18)