Tree species diversity promotes soil carbon stability by depressing the temperature sensitivity of soil respiration in temperate forests

Abstract

The diversity-stability interrelationship suggests that high diversity can buffer fluctuations in environmental conditions such as temperature; we thus hypothesize that tree species diversity will lower the temperature sensitivity of soil respiration (Rs), known as Q10 value. Our hypothesis was tested in a deciduous broad-leaf and a coniferous-broad-leaf mixedwood stand in the warm temperate region in China. We measured soil respiration and indices of tree species diversity including species richness (S), the Berger-Parker index (d), the Simpson index (λ), the Shannon index (He′), and the Pielou evenness index (Je). Our results generally confirm our hypothesis that Q10 was positively correlated to λ, but negatively related to He′, d, and Je, and independent of S, in both stands. However, Rs was independent of the diversity indices. These findings imply that tree species diversity promotes soil carbon stability by depressing the Q10. Furthermore, different biotic and abiotic variables explained the variations of species diversity and Q10 in the broad-leaf and mixedwood forests, suggesting that the mechanisms underlining the effects of tree species diversity on Q10 are different between the two forest types. We conclude that sustainable forest management that improves tree species diversity will increase soil carbon stability and benefit our efforts to mitigate climate change.