Research Projects - Climate Change (Track 1)

Ecological Change

Ecological changes of the landscape scale forced by climate change occur at timescales spanning several orders of magnitude, ranging from severe storms and wildfires to prolonged droughts. Nevada currently lacks capability to detect and analyze climate change effects at a landscape scale. Major observational efforts are already underway in the Sierra Nevada and in the eastern Great Basin to understand how mountain ecosystems and landscapes respond to change in frequency and magnitude of hydroclimatic events, complementing already existing observational networks maintained by federal agencies. The Ecological Change project will enhance Nevada’s capability to measure, analyze, model key ecosystems, and ecohydrologic processes at the landscape scale and understand interactions among climate change, landscape disturbance, and biophysical indicators of ecosystem response, with particular emphasis on how these changes may affect ecosystems including water resources.

Enhanced capabilities will facilitate studies to determine impacts of regional climate change for:

1) Tree growth and regeneration

2) Distribution and composition of native perennial vegetation and invasive species

3) Evapotranspiration in upper elevations

4) Large-scale shifts in types, abundances, and distribution of key species, accompanied by changes in biodiversity and interactions

5) Generation and persistence of aerosols and assessments of their effects on optical properties and ecohydrology

Annual Report Highlights

Trees and the Water Cycle: How Climate Change Could Impact Transpiration and Groundwater Recharge in the Great Basin

Figure 1: Sap velocity (measure of transpiration; green line), soil (blue line) and air temperature (gray line) for White Fir during the growing season.

Outcome: Data recorded from the Nevada Climate-ecohydrology Assessment Network indicated that air and soil temperature strongly modulated patterns of transpiration especially in the spring (Figure 1). Incoming radiation determined the daily periods, but not magnitude of active transpiration. Declines in topsoil (0-30 cm) volumetric water content during the growing season by >20% appeared to have no effect on sap flow, which suggests that soil water availability did not limit water uptake.

Impacts: If the timing and extremity of air and soil temperature patterns are shifted with changes in climate, transpiration patterns could be altered which would influence the amount of water available for groundwater recharge and human use.

Figure 2: Sap flow probe

Explanation: Transpiration, the process by which water that is absorbed through plant roots is evaporated from plant leaves, is an important part of the water cycle in mountain ecosystems. These ecosystems contain “recharge” zones beneath the rooted soil layer where water can flow into the groundwater system, which is then available for naturally occurring vegetation, agriculture and human consumption. If climate change causes trees to transpire more water from the soil layer, less water may flow into the groundwater system. This study is developing a quantitative understanding of the response of transpiration, as measured through sap flow (Figure 2), to environmental factors including air and soil temperature, incoming photosynthetically active radiation, vapor pressure, and soil moisture. Comprehending the interaction between these factors will help determine which factors most influence transpiration rates and how rates may be affected by shifts in these factors under anthropogenic climate change.

Authors: Brittany G. Johnson1,2, Richard L. Jasoni1 and John A. Arnone III1 (Desert Research Institute¹ and University of Nevada, Reno²)

This work was supported by NSF Cooperative Agreement EPS-‐0814372 to the Nevada System of Higher Education.

2010 Annual Highlight

2009 Annual Highlight

Presentations

Ecological Change
Biotic Responses to Climate Change in Great Basin and Mojave	Design and Status of Elevational Transect and Monitoring Sys
Water Source Partitioning for Shrubland Transpiration Using	Waterfall Fire Interpretive Trail Fellowship