Open AccessIntra‐annual and interannual variability of ecosystem processes in shortgrass steppe
Author(s) -
Kelly R. H.,
Parton W. J.,
Hartman M. D.,
Stretch L. K.,
Ojima D. S.,
Schimel D. S.
Publication year - 2000
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2000jd900259
Subject(s) - ecosystem , environmental science , precipitation , primary production , ecosystem model , steppe , atmospheric sciences , terrestrial ecosystem , climatology , carbon flux , climate change , flux (metallurgy) , ecology , meteorology , geography , biology , geology , chemistry , organic chemistry
We used a daily time step ecosystem model (DAYCENT) to simulate ecosystem processes at a daily, biweekly, monthly, and annual time step. The model effectively represented variability of ecosystem processes at each of these timescales. Evolution of CO 2 and N 2 O, NPP, and net N mineralization were more responsive to variation in precipitation than temperature, while a combined temperature‐moisture decomposition factor (DEFAC) was a better predictor than either component alone. Having established the efficacy of CENTURY at representing ecosystem processes at multiple timescales, we used the model to explore interannual variability over the period 1949–1996 using actual daily climate data. Precipitation was more variable than temperature over this period, and our most variable responses were in CO 2 flux and NEP. Net ecosystem production averaged 6 g C m −2 yr and varied by 100% over the simulation period. We found no reliable predictors of NEP when compared directly, but when we considered NEP to be lagged by 1 year, predictive power improved. It is clear from our study that NEP is highly variable and difficult to predict. The emerging availability of system‐level C balance data from a network of flux towers will not only be an invaluable source of information for assessments of global carbon balance but also a rigorous test for ecosystem models.