Using soil sensing technology to examine interactions and controls between ectomycorrhizal growth and environmental factors on soil CO₂ dynamics

摘要

Soils play a critical role in the global carbon cycle, yet the biophysical factors regulating soil CO₂ dynamics remain unclear. We combined high-frequency in situ observations of fine roots and ectomycorrhizal (EM) fungi with data from multiple soil sensor arrays to examine the biophysical interactions influencing soil CO₂ production for one year in a mixed conifer forest. Using structural equation modeling we constructed a hypothesized model to test for causal interactions among environmental factors, biotic factors, and soil CO₂ dynamics throughout the soil profile. According to our model, seasonal variation in CO₂ production was significantly influenced by EM rhizomorph production, soil temperature, and soil moisture. Fine root production, on the other hand, did not appear to significantly influence soil CO₂ production. The relationship between EM rhizomorph production and soil CO₂ production was also supported by a zero temporal lag between these two measurements in a cross-correlation analysis. In contrast, CO₂ production increased before fine root production suggesting that these two measurements were decoupled in time. Results from this study highlight the need to better understand differences in carbon allocation between plant roots and EM fungi to improve our predictions of soil carbon dynamics under global climate change.