Author Description

Rangelands comprise more than 30% of global land area and provide a broad range of ecosystem services ‒ including food and forage production, soil and water resource protection, biodiversity, and wildlife habitat. In California, rangelands span about 57 million hectares, taking up nearly 60% of the state's land area, encompassing the Central Valley, as well as the coastal and foothill ranges. Forage production from these rangelands not only provides bases for many ecosystem services but also supports a 3-billion-dollar beef production every year. However, forage production in California has considerable year-to-year variation due to precipitation and temperature variability. The forage production also varies significantly from place to place due to California's complex topography-induced microclimates and spatial variability in soil properties. These spatiotemporal variations in rangeland productivity make balancing economic (grazing), conservation (habitat), and environmental (erosion/water quality) objectives a big challenge, especially during an era of climate change. The present work aims to examine relationships between rangeland forage production and its potential drivers at different scales to generate knowledge and tools that can help the ranching community and policymakers to make better management decisions. The first chapter focused on developing optimized methods to map forage production at a 30-cm resolution using multispectral remote sensing images. We estimated aboveground net primary production as a product of absorbed photosynthetically active radiation (APAR) derived from NDVI and light use efficiency (LUE), optimized as a function of topography and climate stressors. The estimated forage production agreed well with field measurements having an R2 of 0.80 and RMSE of 542 kg/ha. Cumulative NDVI and APAR were less correlated with measured biomass (R2= 0.68). This chapter demonstrated the utility of aerial and satellite remote sensing technology in su