Effect of soil moisture on the temperature sensitivity of Northern soils

Christina Minions, Woods Hole Research Center, cminions@whrc.org (Presenter)
Susan M. Natali, Woods Hole Research Center, snatali@whrc.org
Sarah Ludwig, Woods Hole Research Center, ludda.ludwig@gmail.com
Dave Risk, St. Francis Xavier University, Canada, drisk@stfx.ca

Arctic and Boreal ecosystems are vast reservoirs of carbon, and are particularly sensitive to climate warming. Changes in the temperature and precipitation regimes of these regions could significantly alter soil respiration rates, impacting atmospheric concentrations and affecting climate change feedbacks. Many incubation studies have shown that both temperature and soil moisture are important environmental drivers of soil respiration; this relationship, however, has rarely been demonstrated with in situ data. Here we present the results of a study at six field sites in Alaska from 2016 to 2017. Low-power automated multiplexer soil gas systems were used to measure soil surface CO₂ flux from three forced diffusion chambers and soil profile concentrations from three soil depth chambers at hourly intervals at each site. HOBO Onset dataloggers were used to monitor soil moisture and temperature profiles. Temperature sensitivity (Q10) was determined at each site using inversion analysis applied over different time periods. With highly resolved data sets, we were able to observe the changes in soil respiration in response to changes in temperature and soil moisture. Through regression analysis we confirmed that temperature is the primary driver in soil respiration, but soil moisture becomes dominant beyond a certain threshold, suppressing CO₂ flux in soils with high moisture content. This field study supports the conclusions made from previous soil incubation studies, and provides valuable insights into the impact of both temperature and soil moisture changes on soil respiration.

Associated Project(s): 

• Natali-01

Poster Location ID: 74

Session Assigned: Carbon Dynamics