Impact of Vegetation Cover on Ecosystem Services in Carbon-Water Interactions

1. Carbon-water interactions with grassland to plantation conversions: effect of vegetation cover on the production of ecosystem services Kathleen Farley, San Diego State University, USARobert Jackson, Duke University, USAEsteban Jobbagy, Roni Avissar, Somnath Baidkya Roy, Damien Barrett, Charles Cook, David LeMaitre, Bruce McCarl, Brian Murray

2. Conversion of grasslands to plantations: new policy/market incentives • Kyoto Protocol Clean Development Mechanism • Issued first CERs (Certified Emission Reductions) in October 2005 • EU Emission Trading Scheme • $4.5 billion in emissions credits in 2005 • Chicago Climate Exchange

3. South America: plantation area and potential expansion Source: World Forest Institute

4. How does afforestation alter ecosystem processes, in particular water yield

5. Compiled global data set on afforestation effects on water yield

6. Global synthesis • Annual runoff data from afforested sites with a previous land cover of grassland or shrubland • Included 26 data sets, most from paired catchment studies, with 504 annual observations • Analyzed change in runoff as related to original vegetation type, plantation species,plantation age, and mean annual precipitation

7. Results • Runoff reductions >75% for at least one year in 1/5 of catchments • Runoff reductions, averaged across all plantation ages, were greater in grasslands (44 ± 3%) than shrublands (31 ± 2%) (p<0.001) • Eucalypts had greater effect on runoff than pines in sites that were originally grasslands (75 ± 10% vs 40 ± 3%) (p<0.001)

8. Change in runoff with plantation age Farley et al. 2005

9. Change in runoff with plantation age Farley et al. 2005

10. Change in runoff with plantation age

11. Change in runoff in wet and dry regions Farley et al. 2005

12. Vegetation-climate feedbacks • Simulations for the easterns U.S. (Forest and Agricultural Sector Optimization Model-GHG): crops and pasture replaced by hardwood and softwood plantations • Regional Atmospheric Modelling System: in these locations, higher water use of plantations not offset by increased precipitation Jackson et al. 2005

13. Vegetation-climate feedbacks • Summer ET increased by >0.3 mm/day, summer surface air temperature decreased by up to 0.3°C, precipitation decreased by as much as 30 mm/month • No evidence for increased rainfall from local convection in most locations Jackson et al. 2005

14. Soil quality effects Jackson et al. 2005

15. VEGETATION PATTERN ECOSYSTEM PROCESS PRODUCTION OF ECOSYSTEM SERVICES

16. Production of ecosystem services with grassland to plantation conversion • There is a carbon for water tradeoff when plantations are established • Previous land cover type affects the severity of the tradeoff • Larger, more sustained streamflow reductions when grasslands planted than shrublands • Plantation species affects the severity of the tradeoff • More severe streamflow reductions with eucalypts than pines • Climatic zone affects the severity of the tradeoff • Lower rainfall zones may be more severely impacted

17. Vulnerability assessment • How sensitive is the system to shocks, stresses, or disturbances? • What is the current state of the system relative to the threshold of change? • What is the system’s ability to adapt to changing conditions? From Luers 2005

18. Vulnerability & water yield • How large is the change in runoff relative to available water resources? • Change in runoff as a percent of mean annual precipitation consistently ~14-15% • Comparison with renewable water can guide policy in areas with limited information

19. 500 Asia 400 30% Canada World 300 Europe Mozambique USA Swaziland Mean annual renewable water (mm) Malawi 200 Lesotho Angola Africa 10% Israel 100 Namibia Zimbabwe Australia South Africa Botswana 0 200 400 600 800 1000 1200 Mean annual rainfall (mm) Jackson et al. 2005

20. Vulnerability assessment From Luers 2005

21. Land use change & ecosystem services • Vulnerability not just to change in a single service, but to a suite of ecosystem services • Scale issues are a challenge to analysis: C vulnerability global, water vulnerability local • Uneven markets also a challenge

22. VEGETATION PATTERN policy ECOSYSTEM PROCESS PRODUCTION OF ECOSYSTEM SERVICES

23. Ecuadorian example • Páramo grasslands are primary source of drinking water • e.g. Sistema Papallacta provides 50% of Quito’s drinking water, estimated at $2.5 million/year • Grassland to plantation conversions likely to reduce water supply

24. Ecuadorian example • FONAG: Water fund that collects payments from water users for watershed protection • Proposed forestry law: limit plantations above 3500 m

25. VEGETATION PATTERN policy ECOSYSTEM PROCESS PRODUCTION OF ECOSYSTEM SERVICES

26. Acknowledgements • Duke University Center on Global Change • National Science Foundation • US Department of Energy, Southcentral Regional Center of NIGEC