Abstract Detail

Dynamics and Demography of Alpine Islands

Duran, Sandra Milena [1], Henderson, Amanda [2], Wilmer, Chelsea [2], Falco, Nicola [3], Steltzer, Heidi [4], Brodie, Eoin [3], Wainwright, Haruko  [3], Saleska, Scott R. [1], Enquist, Brian J. [1].

Effects of early snowmelt on carbon fluxes and plant traits in Alpine meadows.

Alpine meadows are characterized by an early (foresummer) drought that occurs after snowmelt, and lasts until the start of the monsoon season (mid-summer). Current climate models predict an increase in the length and severity of this dry period due to earlier snowmelt dates, increases in air temperature, and shifts in the beginning and intensity of the North American monsoon. These climatic changes may influence the rates of photosynthesis by plants due to lower water availability in the soil. However, it is unclear how these changing precipitation regimes may influence above- and belowground carbon fluxes directly via changes in the abiotic environment, and indirectly via shifts in plant communities due to environmental stress. For example, a lower snowpack with faster melting snow would expose plants to longer and drier periods before the onset of monsoonal moisture. Alpine meadows in Gothic, Colorado experienced a strong foresummer drought in 2018. This drought was caused by a low snowpack and high temperatures, which led to reductions of summer rainfall before the July Monsoons. To understand how these climatic conditions, influence plant communities and carbon uptake, we measured species composition, plant traits, and above-and belowground carbon fluxes in 18 plots were snowmelt was artificially accelerated, and 18 plots under normal conditions. Plots (1.3 m²) were located in three sites spanning an elevation gradient of 2780 to 3120 meters above sea level. We also measured plant traits using ground-based and remotely-sensed methods in early and peak season to evaluate the potential or remotely-measured traits to predict plant responses. We found that early snowmelt affected soil fluxes and soil temperature. Soil fluxes increased along elevation across all plots, with greater fluxes under earlier snowmelt. These results appear to be associated with higher variability in soil temperature and lower soil moisture in manipulated plots. Overall, plant traits such as leaf mass per area and leaf water content did not show differences between experimental and control plots in early season, and in the peak season we only found differences in plots at lower elevation. Remotely-measured plant traits showed similar responses to ground-based measurements, which highlights the importance of using imaging spectroscopy to monitor plant responses to climate change in alpine communities. Future analysis will evaluate the impact on other physiological traits such as foliar nutrients and water use efficiency, and the overall impact of early snowmelt on above ground processes such as carbon biomass and ecosystem productivity.

1 - University of Arizona, Department of Ecology and Evolutionary Biology, 1041 E Lowell St, Room 310, Tucson, AZ, 85721-0001, United States
2 - Rocky Mountain Biological Laboratory, 8000 County Road 317, Gothic, Colorado, 81224, USA
3 - Lawrence Berkeley National Laboratory, Climate & Ecosystem Sciences Division, 1 Cyclotron Road, MS 74R-316C, Berkeley, CA, 94720, United States
4 - Fort Lewis College, Department of Biology, Durangp, Colorado, 81301, United States

Keywords:
Alpine plants
Early snowmelt
Plant functional traits
Carbon cycling
Leaf spectroscopy.

Presentation Type: Colloquium Presentations
Session: CO02, Dynamics and demography of Alpine Islands
Location: San Luis 2/Starr Pass
Date: Monday, July 29th, 2019
Time: 11:00 AM
Number: CO02012
Abstract ID:1035
Candidate for Awards:None