South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China.
PLoS One. 2012;7(7):e41493. doi: 10.1371/journal.pone.0041493. Epub 2012 Jul 23.
The aim of this study was to determine response patterns and mechanisms of soil respiration to precipitation increases in subtropical regions.
METHODOLOGY/PRINCIPAL FINDINGS: Field 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/SIGNIFICANCE: Our results indicate that precipitation increasing in subtropical regions in China may have limited effects on soil respiration.
本研究旨在确定亚热带地区土壤呼吸对降水增加的响应模式和机制。
方法/主要发现：在中国亚热带的三个典型森林（即松林（PF）、阔叶林（BF）和松阔混合林（MF））中设置了野外试验小区，分别进行双降水（DP）处理和自然降水（AP）处理。在三年的时间里，测量了土壤呼吸、土壤温度、土壤水分、土壤微生物生物量和细根生物量。我们通过 R = (a + cM)exp(bT) 检验了降水处理是否影响土壤呼吸速率（R）与土壤温度（T）和土壤水分（M）的关系，其中 a 是与基础土壤呼吸相关的参数；b 和 c 是与土壤呼吸对温度和水分敏感性相关的参数。结果表明，DP 处理仅略微增加了 PF 的年平均土壤呼吸（15.4%），而对 MF 和 BF 的土壤呼吸没有显著影响。在 BF 中，土壤呼吸的增加与土壤细根生物量和微生物生物量的增强有关。DP 处理没有改变模型参数，但增加了土壤水分，导致土壤呼吸略有增加。在 MF 和 BF 中，DP 处理降低了土壤温度敏感性 b，但增加了基础土壤呼吸 a，导致土壤呼吸没有显著变化。
结论/意义：我们的结果表明，中国亚热带地区降水的增加可能对土壤呼吸的影响有限。
