QUANTIFYING THE INFLUENCE OF CLIMATE, LANDSCAPE STRUCTURE, AND PLANT PHYSIOLOGICAL RESPONSES ON SPATIAL PATTERNS OF TRANSPIRATION AND FOREST PRODUCTIVITY
This project is in collaboration with Dr. Kelsey Jencso at the University of Montana
In the Western U.S., forest productivity is largely controlled by water availability. However, increasing spring air temperatures and declining snowpacks have led to decreased water availability and gross primary productivity, increased tree mortality rates, and increased fires.
Climate models suggest that these trends will extend into the future and that ecological sensitivity to water limitation could vary markedly along elevation gradients. We also know that the landscape structure control how water moves within a watershed.
At the Lubrecht Experimental Forest near Missoula, MT, we are investigating three main research questions:
- how does landscape structure mediate the spatial patterns of water delivery, storage, and availability;
- what are the resulting tree responses to these spatial and temporal patterns of water availability under different precipitation regimes; and,
- how do the vegetation responses then control the connectivity of subsurface hydrologic flow paths to the stream network.
We are conducting hydrometric, physiological, and geospatial analyses across a watershed with diverse topographic features. We are also measuring tree growth, using sap flow sensors to quantify transpiration rates, and doing oxygen and hydrogen isotope anlaysis to partition source water use within a growing season.
We are also developing wireless sensor technology so that we can measure soil moisture, temperature, air temperature, relative humidity, as well as sap flow across a watershed that differs in elevation, aspect, and hillslope position. These wireless sensors will allow us to examine the high degree of variability we expect to see in these parameters across both space and time.