WP coordinator meeting June 17/ WP3 progress report

ReferenceLand-use transitions Response variable or main effect Stratification or main contrast Number of observations and studies Main conclusions Allen, 1985forest 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, 1986uncultivated 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;estima ted 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 plotsNo 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 2002afforestationabsolute 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)* 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 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 ReferenceLand-use transitionsResponse variable or main effect Stratification or main contrast Number of observations and studies Main conclusions

Silver et al 2004tropical secondary succession and tree plantations regressed soil C stocks on stand age previous land use and life zones : dry ( 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, 2009afforestation, 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, 2010afforestation,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) ReferenceLand-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 transitionDepth% ChangeLog ratio Mean95%CIMean95% CI forest to crop (107)All to to forest to pasture (289) to to forest to plantation (69) to to SC: forest to crop (54) to to SC: crop to forest fallow (26) to to crop to pasture (7) to to crop to plantation (48) to to crop to secondary forest (26) to to pasture to plantation (89) to to pasture to secondary forest (165) to to 0.115

forest to crop (32)0-10 cm to to forest to pasture (98) to to forest to plantation (13) to to SC: forest to crop (7) to to crop to plantation (17) to to crop to secondary forest (11) to to pasture to plantation (25) to to pasture to secondary forest (18) to to savanna to crop (7) to to savanna to plantation (7) to to Land-use transitionDepth% ChangeLog ratio Mean95%CIMean95% CI

forest to crop (5)0-100 cm to to forest to pasture (5) to to forest to plantation (11) to to pasture to secondary forest (5) to to savanna to crop (5) to to Land-use transitionDepth% ChangeLog ratio Mean95%CIMean95% CI

forest to pasture (0-30 cm) < 4 yrs (N=20) 5-9 yrs (N=27) yrs (N=32) yrs (N=32) > 40 yrs (N=14) < 1500 mm (N=6) mm (N=30) mm (N=60) 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) yrs (N=33) yrs (N=12) > 40 yrs (N=5) mm (N=14) mm (N=13) 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) yrs (N=25) yrs (N=25) > 40 yrs (N=7) < 1500 mm (N=5) mm (N=27) mm (N=36) 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) mm (N=13) mm (N= mm (N=24) >3500 (N=40) low activity clay (N=70) allophanic (N=18)