Effects of Climate Change on Decomposition in Arctic Tussock Tundra: A Modeling Synthesis
Moorhead DL and Reynolds JF. 1993. Effects of Climate Change on Decomposition in Arctic Tussock Tundra: A Modeling Synthesis. Arctic and Alpine Research. 25(4):403-412
A model of litter decomposition (GENDEC; Moorhead and Reynolds, 1991) is used to examine the potential effects of changing soil climate on the decay of dead organic matter in a tussock tundra soil of northern Alaska, U.S.A. Model behavior under current climatic conditions is consistent with observations from field and laboratory studies of decomposition and plant growth (5.28 g N · m-2· yr-1 turnover and 79.5 g CO2-C· m-2· yr-1 released, respectively). Under changing conditions, carbon and nitrogen release from dead organic matter increase as linear functions of both season length and temperature, and as roughly parabolic functions of soil moisture content. The greatest increase in net N release from dead organic matter (199% of current value), occurs at optimum soil moisture (600%), longest season (140 d) and highest mean summer temperature (8.5°C). The least amount of N is immobilized (46% of current value) at the lowest temperature (currently 4.5°C), shortest season (70 d) and highest soil moisture content (1000%). Season length has little effect on the size of the mineral N pool, although pool size does respond to differences in temperature and soil moisture content and ranges from 12 to 25 mg N · m-2. This study also demonstrates an explanation for inconsistencies between the reported responses of carbon and nitrogen dynamics of tundra soils to changes in soil moisture and temperature regimes. Net carbon mineralization (usually estimated as cumulative CO2 efflux) roughly is proportional to total carbon transfer through the decomposer community because a substantial fraction of this carbon flux is respired. However, net nitrogen mineralization is not necessarily related to total nitrogen flux because of the high immobilization potential of tussock tundra and high assimilation efficiency. Therefore, patterns of carbon and nitrogen mineralization need not be similar.
- Type
- Journal Article
- Authors
- Moorhead, Daryl; Reynolds, James
- Units
- CAKR , KOVA , NOAT
- Keywords
- Cape Krusenstern National Monument, Kobuk Valley National Park, Noatak National Preserve