The Sierra Nevada Files

Fire exclusion (i.e., trying to eliminate fires from the landscape) was, for much of the 20th century, the prevailing policy in the management of forests in the Sierra Nevada. Much has been written on the effects of this management strategy on creating landscapes vulnerable to destructive fires, but there's been little research on how fire exclusion might affect the resilience of forests to other potentially damaging events. A recent paper by van Mantgem and colleagues in forests   helps to fill that gap by examining how fire may affect the ability of forests to withstand droughts. Mechanical thinning and prescribed fires are common strategies for reducing fuel load and they may also benefit the remaining trees by reducing the competition for sunlight, water, and nutrients. The authors of this paper were interested to know whether the removal of small trees by prescribed fires, alone, could confer advantages to the remaining trees, without the added benefits derived from mechanical...

Plants rely on rainfall and groundwater to stay alive, with the relative proportion of each varying according to different factors such as rainfall seasonality and rooting depth. In periods of drought, plants must increase their dependency on groundwater; however, not all groundwater is the same. Some groundwater systems are recharged by recent precipitation, while others continue to transmit water from storms that happened several decades or even centuries in the past. In a 2021 paper published in Environmental Research Letters, Zach Meyers and his colleagues sought to answer an important question: do plants nourished by old groundwater do better than those dependent on young groundwater? They hypothesized that the former would do better during periods of drought because the old groundwater source would be less affected by the current climatic conditions and, thus, would vary less and be more consistent. From 2011-2017 California experienced its worst 6-year drought on record, prov...