New England WSC Seminar series Simeone 20190424

Science Center Objects

Forest cover is predicted to decline in the western US in the next century, due in part to increased hydraulic stress associated with climate change. There has been a large body of work done on adult trees in natural settings, but a smaller amount has been done on more vulnerable seedlings outside of the greenhouse.

Date/Time: Wednesday, April 24, 2019, 12:00 pm

Title: Ecohydrology in the Semiarid West, how does water stress constrain lowland forest distribution?

Presented by: Caelan Simeone, Hydrologist, USGS New England WSC

Location: USGS, Massachusetts Office, Northborough, MA

Abstract: 

Forest cover is predicted to decline in the western US in the next century, due in part to increased hydraulic stress associated with climate change. There has been a large body of work done on adult trees in natural settings, but a smaller amount has been done on more vulnerable seedlings outside of the greenhouse. We modeled water stress in ponderosa pine seedlings at the greenhouse, stand, and watershed scales to examine its influence on mortality and the extent of lowland forests in the northern Rocky Mountains. We showed that cumulative hydraulic stress, its legacy and its consequences for mortality are predictable and can be modeled at local to landscape scales. Topography and hydrologic processes exert major controls on the distribution and availability of water and energy drive spatial patterns of hydraulic stress. Low‐elevation, south‐facing, nonconvergent locations with limited upslope water subsidies experienced the highest rates of modeled mortality. Simulated mortality in seedlings from 2001 to 2015 correlated with the current distribution of forest cover near the lower treeline, suggesting that hydraulic stress limits recruitment and ultimately constrains the low‐elevation extent of conifer forests within the region.