The San Francisco Bay Area in California, USA is a highly heterogeneous region in climate, topography, and habitats, as well as in its political and economic interests. Successful conservation strategies must consider various current and future competing demands for the land, and should pay special attention to livestock grazing, the dominant non-urban land-use. The main objective of this study was to predict changes in rangeland forage production in response to changes in temperature and precipitation projected by downscaled output from global climate models. Daily temperature and precipitation data generated by four climate models were used as input variables for an existing rangeland forage production model (linear regression) for California’s annual rangelands and projected on 244 12 km x 12 km grid cells for eight Bay Area counties. Climate model projections suggest that forage production in Bay Area rangelands may be enhanced by future conditions in most years, at least in terms of peak standing crop. However, the timing of production is as important as its peak, and altered precipitation patterns could mean delayed germination, resulting in shorter growing seasons and longer periods of inadequate forage quality. An increase in the frequency of extremely dry years also increases the uncertainty of forage availability. These shifts in forage production will affect the economic viability and conservation strategies for rangelands in the San Francisco Bay Area.
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机译：美国加利福尼亚州的旧金山湾地区在气候，地形和栖息地以及政治和经济利益方面都是高度异质的地区。成功的保护策略必须考虑到当前和未来对土地的各种竞争需求，并应特别注意畜牧业，这是主要的非城市土地利用方式。这项研究的主要目的是根据全球气候模式下产量下降所预测的温度和降水变化，预测牧场牧草产量的变化。四种气候模式产生的每日温度和降水数据被用作加利福尼亚州每年牧场的现有牧场牧草生产模型（线性回归）的输入变量，并预测了八个湾区县的244个12 km x 12 km网格单元。气候模型预测表明，湾区牧场的牧草产量可能会在未来几年内在大多数情况下得到提高，至少在最高收成方面。但是，生产时间与其高峰一样重要，改变降水方式可能意味着发芽延迟，从而导致生长季节缩短和草料质量不足的时间更长。极端干旱年份的频率增加也增加了草料供应的不确定性。牧草产量的这些变化将影响旧金山湾地区牧场的经济可行性和保护战略。
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