Environmental variation is directly responsible for short‐ but not long‐term variation in forest‐atmosphere carbon exchange

作者：Andrew D. Richardson, David Y. Hollinger, John D. Aber, Scott V. Ollinger, B. H. Braswell · 发表于：Global Change Biology · 年份：2007 · DOI：10.1111/j.1365-2486.2007.01330.x · 被引用次数：255 · 研究领域：Plant Water Relations and Carbon Dynamics、Atmospheric and Environmental Gas Dynamics、Climate variability and models

Abstract Tower‐based eddy covariance measurements of forest‐atmosphere carbon dioxide (CO 2 ) exchange from many sites around the world indicate that there is considerable year‐to‐year variation in net ecosystem exchange (NEE). Here, we use a statistical modeling approach to partition the interannual variability in NEE (and its component fluxes, ecosystem respiration, R eco , and gross photosynthesis, P gross ) into two main effects: variation in environmental drivers (air and soil temperature, solar radiation, vapor pressure deficit, and soil water content) and variation in the biotic response to this environmental forcing (as characterized by the model parameters). The model is applied to a 9‐year data set from the Howland AmeriFlux site, a spruce‐dominated forest in Maine, USA. Gap‐filled flux measurements at this site indicate that the forest has been sequestering, on average, 190 g C m −2 yr −1 , with a range from 130 to 270 g C m −2 yr −1 . Our fitted model predicts somewhat more uptake (mean 270 g C m −2 yr −1 ), but interannual variation is similar, and wavelet variance analyses indicate good agreement between tower measurements and model predictions across a wide range of timescales (hours to years). Associated with the interannual variation in NEE are clear differences among years in model parameters for both R eco and P gross . Analysis of model predictions suggests that, at the annual time step, about 40% of the variance in modeled NEE can be attributed to variati...