1. Interactions of Land Use and Global Environmental Change on Watershed-scale Processes Lars Pierce, Fred Watson, Melinda Mulitsch, Wendi Newman, Adrian Rocha, Jodiah Nelson, Mark Fain, and others Institute of Earth Systems Science & Policy California State University, Monterey Bay Seaside, California 93955 lars_pierce@csumb.edu

2. Water Resource Issues in the Salinas Valley: How do LULC and global-scale environmental changes (climate, CO 2, etc.) influence water and carbon cycling? How do the impacts of LULCC vs. GEC compare? How effective are management policies designed to reduce the impacts of land use change on water resources?

3. CO 2 ETPSPS H2OH2OC N N RHRH N loss N dep Plant Soil PPT Material FluxConstraint C CLCL N up Root Leaf Root Leaf RORO RARA NLNL LAI TfTf Schematic flowchart of the BIOME-BGC Ecosystem Model. BGC Model Integrated Water, C, N cycles (Running et al. models) Timestep: Daily Spatial Scale: Homogeneous plot (~30m) 1 vegetation, 1 soil layer Driving Variables: Daily climate (T, ppt) Vegetation / Land Cover Leaf Area Index Soil text, depth, C, N Key Processes: Water: Rain/Snow, Interception, Soil Moisture, ET, Runoff Carbon: Photosynthesis, Growth, Respiration, Turnover Nitrogen: Uptake, Allocation, Turnover, Loss

4. Measured Biomass (g m -2 yr -1 ) Simulated Biomass (g m -2 yr -1 ) Figure 2. Measured above-ground biomass compared to the above-ground biomass simulated using BIOME-BGC for the water x CO2 experiment in the Jasper Ridge CO 2 project (Field et al., 1997).

5. Photo courtesy of Fred Watson

6. Salinas Valley of the Future? Atmospheric CO2: 700 ppmv Temperature: +3.5 ± 2 o C Precipitation: +25%, Seasonality? Nitrogen Deposition Land Use: Oak, Agriculture Separate vs. Combined Responses to Change 1994 - 96 Daily Climate for Salinas, California Equilibrium Fluxes and Pools for NPP, Water Use Agriculture: No N, Water Limitations; 3 crops/yr.

7. Lettuce Yield Not much effect on total yield; significant impact on timing of harvest +2.5C (harvest 5 days earlier) 2xCO2 (harvest 10-15 days earlier) growth prepfallow

8. LULC vs. Environmental Change (Net Recharge = Runoff-Irrigation)

9. Plot-level Conclusions Oak Woodland Responsive to changes in CO2, T, PPT, N (10-30%) Large Interactions (5-15%) Agriculture Responsive to changes in CO2, T only (5-20%) Small Interactions (< 5%) Land Cover Change > Environmental Change

10. Photo courtesy of Fred Watson LULC vs. GEC at the watershed-scale

11. Land Use / Land Cover Gabilan Ck Watershed (94 km 2 ) Derived from 1995 Landsat TM Crops (8%) Urban (1%) Oak Woodland (26%) Grassland (51%) Chaparral (14%)

12. Gabilan Ck Simulations 4 Simulations: LULC vs. Climate Change 1995 LULC (Present): –Ambient & 2xCO 2 Climate ~1800 LULC (Past, Ag/Urban -> Grassland ): –Ambient & 2xCO 2 Climate Separate vs. Combined Responses to Change 1996 - 98 Daily Climate for Salinas, California Agriculture: No N, Water Limitations; 2-3 crops/yr.

13. Leaf Area Index vs. Satellite Reflectance Courtesy of Fred Watson, CSUMB

14. Gabilan Ck Watershed LULC vs. Climate Change @ Watershed-scale +41mm-44mm Land Use / Land Cover (Net Recharge = Runoff-Irrigation)

15. Conclusions Plot scale LULC >> Temperature, CO 2 Changes Watershed scale LULC ~ Temperature, CO 2 changes 10% Ag/Urban Land Use

16. Simulated Effects of ENSO on Soil Moisture and Evaporation, 1997 - 1998, Chualar Creek Oak Woodland & Chaparral Agriculture Movie Link

17. Fred Watson’s Tarsier: http://science.csumb.edu/~tarsier/http://science.csumb.edu/~tarsier/ MacaqueBGC

18. VSIM

20. Monterey County Land Use, 2000 Map created by Wendi Newman, CSUMB

21. ParameterSourceDerived Inputs Models Outputs Climate NWS CIMIS Temperature Precipitation Topography USGS Elevation Slope, Aspect Land Cover TM AVHRR Vegetation Type, Amount SoilsNRCS Soil Texture Land Use AMBAG Zoning Density MTCLIM BGC Macaque Microclimate Runoff Water Use Water Stress Productivity Leaching NWS - National Weather Service USGS - US Geological Survey NRCS - USDA Natural Resources Conservation Service AMBAG - Assoc. of Monterey Bay Area Govts. TM - LANDSAT Thematic Mapper AVHRR - NOAA Adv. Very High Resolution Radiometer MTCLIM - climate interpolation model BGC - ecosystem process model Regional Hydro-Ecological Simulation System (RHESSys)

23. Irrigation Water Use +T - not much impact on irrigation water use (due to shorter crop rotation) 2xCO2 - 14% reduction in irrigation water use (1 less event)