Influence of snow cover duration on soil evaporation and respiration efflux in mixed‐conifer ecosystems

Subalpine mixed-conifer ecosystems are dependent on snowfall, which is expected to decrease under projected climate change. Changes in snowpack are likely to have important consequences for water and carbon cycling in these and downstream ecosystems. Particularly within semi-arid environments, snowpack changes will directly influence localized water and carbon dynamics and indirectly influence regional-scale levels of water availability and carbon sequestration. In this study, we monitor soil evaporation (E) and soil respiration (R) and evaluate how snow cover affects these effluxes within a mixed-conifer ecosystem within the Santa Catalina Mountains about 10km north of Tucson, Arizona. Using time-lapse digital photos, we identified areas of consistent short and long snow duration, and we monitored E and R in these areas every 2weeks for 15months. Our primary findings include the following: (1) Dynamics of E are not different between long and short snow season sites, (2) E for both short and long snow seasons has a strong relationship with soil moisture and a poor relationship with soil temperature, (3) dynamics of R vary between long and short snow season sites throughout the year, with short snow season fluxes typically higher than those of long snow season sites, and (4) R for short and long snow seasons has a strong relationship with soil temperature and a poor relationship with soil moisture. Because climate change will only exacerbate both drying-wetting and cooling-warming cycles, detangling these complex relationships becomes increasingly important for understanding shifts in carbon dynamics in these subalpine mixed-conifer ecosystems. Copyright (c) 2013 John Wiley & Sons, Ltd.