Responses of soil microbial respiration to plantations depend on soil properties in subtropical China

摘要

Assessing the impact of plantation on microbial respiration (MR) is vitaly important to understand the interactions between belowground metabolism and land use change. In this study, cumulative MR was determined by alkali absorption method in 1, 3, 7, 14, 21, 28, 35, 42, 49, and 56 days from the soil in a representative plantations in the subtropical region of China. The treatment of plantations contained no plant (CK), orange trees (Citrus reticulata)+Bahia grass (Paspalum notatum) (GB), orange trees (C. reticulata)+Bahia grass (P.notatum)+soybean (Giycine max(L.)Merril) (GBH). Results showed that plantation had signiifcant effects on microbial respiration and the responses of microbial respiration to plantation from different soil layers and topographies were different: in 0–20 cm in uphil: GB>GBH>CK; in 20–40 cm in uphil: GBH>CK>GB; in 0–20 cm in downhil: GBH>CK>GB; in 20–40 cm in downhil: GB>CK>GBH. Furthermore, plantation also altered the relationships between MR and soil properties. In CK, microbial respiration was positively correlated with NH4+ and soil total N, and negatively correlated with soil moisture, pH, NO3–, and microbial biomass carbon (MBC). In GB, microbial respira-tion under GB signiifcantly negatively correlated with dissolved organic carbon (DOC). In GBH, microbial respiration under GBH was positively correlated with NH4+, MBC, total soil carbon (TC), and total soil nitrogen (TN), and negatively correlated with soil moisture (SM), pH, NO3–, and DOC. The underlying mechanisms could be attributed to soil heterogeneity and the effects of plantation on soil properties. Our results also showed that plantation signiifcantly increased soil C storage, which suggested plantation is a key measure to enhance soil C sequestration and mitigate global CO2 emission, especialy for the soil with low initial soil carbon content or bared soil.