Abstract
BackgroundThe aim of this study was to determine response patterns and mechanisms of soil respiration to precipitation increases in subtropical regions.Methodology/Principal FindingsField plots in three typical forests [i.e. pine forest (PF), broadleaf forest (BF), and pine and broadleaf mixed forest (MF)] in subtropical China were exposed under either Double Precipitation (DP) treatment or Ambient Precipitation (AP). Soil respiration, soil temperature, soil moisture, soil microbial biomass and fine root biomass were measured over three years. We tested whether precipitation treatments influenced the relationship of soil respiration rate (R) with soil temperature (T) and soil moisture (M) using R = (a+cM)exp(bT), where a is a parameter related to basal soil respiration; b and c are parameters related to the soil temperature and moisture sensitivities of soil respiration, respectively. We found that the DP treatment only slightly increased mean annual soil respiration in the PF (15.4%) and did not significantly change soil respiration in the MF and the BF. In the BF, the increase in soil respiration was related to the enhancements of both soil fine root biomass and microbial biomass. The DP treatment did not change model parameters, but increased soil moisture, resulting in a slight increase in soil respiration. In the MF and the BF, the DP treatment decreased soil temperature sensitivity b but increased basal soil respiration a, resulting in no significant change in soil respiration.Conclusion/SignificanceOur results indicate that precipitation increasing in subtropical regions in China may have limited effects on soil respiration.
Highlights
Soil respiration in terrestrial ecosystems plays an important role in global carbon cycling and climate change [1,2,3,4]
Soil respiration responses to precipitation treatments could be caused by either changes in environmental factors such as soil temperature and moisture, or functional changes – which are defined as changes in model parameters of soil respiration with soil temperature and moisture, or both [23]
As no changes in soil microbial biomass and fine root biomass were observed in the broadleaf forest (BF) treatment and only slight change in soil microbial biomass in the mixed forest (MF), little change in soil respiration was observed in the MF and the BF
Summary
Soil respiration in terrestrial ecosystems plays an important role in global carbon cycling and climate change [1,2,3,4]. Considering that tropical and subtropical forests contain more than 25% of the carbon in the terrestrial biosphere, it is imperative to improve our mechanistic understanding of soil respiration responses to precipitation and soil moisture changes [15,16]. Soil respiration includes both respiration of living roots and microbial respiration resulted from microbial decomposition of litter and soil organic matter [3,5,10,12]. The aim of this study was to determine response patterns and mechanisms of soil respiration to precipitation increases in subtropical regions
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