Effects of Changes in Soil-Based Properties on Soil Respiration in Pinus yunnanensis in Central Yunnan under Nitrogen Deposition
- LIANG Yangsen, WANG Keqin, SONG Yali, ZHENG Xingrui, HU Chun
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【Objective】 The current study was conducted to study the effects of changes in soil physicochemical properties, microbial characteristics and enzyme activities on soil respiration in wet and dry seasons under the background of nitrogen deposition, and to provide scientific basis for carbon cycle and material cycle and energy flow in subtropical forest ecosystems. 【Method】 The alpine Pinus yunnanensis in Central Yunnan were selected for the study. Soil physicochemical properties, enzyme activities, soil microbial population, microbial biomass carbon （MBC）, microbial biomass nitrogen （MBN） and soil respiration under simulated N deposition （CK 0 g/（m2·a）, low N LN 10 g/（m2·a）, medium N MN 20 g/（m2·a）, high N HN 25 g/（m2·a）） in wet and dry seasons were investigated in this study to elucidate the seasonal variation of soil respiration under N deposition and the response relationship between soil respiration and soil properties, and to explore the relevance of the coupling mechanism. 【Result】 ① Soil TN and NH4+-N were significantly increased under all N treatments compared to CK. ② During the wet-dry season, urease was significantly increased by 16.38%-67.95% in HN; sucrase was significantly decreased by 19.65%-35.65% in HN; catalase was significantly increased by 11.11%-100.00% in LN, MN, and HN; while polyphenol oxidase was significantly decreased in MN, HN by 8.69%-25.00%, compared to CK.③Compared to control, soil microbial population and MBC was significantly increased in LN, MN （4.70%-30.52%） but significantly decreased in HN （18.57%-57.20%）; MBN was significantly decreased in HN （6.80%-13.70%）.④N deposition promoted soil respiration in the wet season, however HN inhibited soil respiration in the dry season; across the tested period, HN changed from promoting to inhibiting effect on soil respiration. Soil respiration was significantly correlated with soil temperature and moisture; Q10 of LN, HN increased by 7.41%, 60.27%, respectively.⑤In the wet season, soil respiration was significantly and positively correlated with TN, TP, TK, NH4+-N, NO3--N, and urease, but was significantly and negatively correlated with sucrase, polyphenol oxidase, microbial population, MBC, and MBN; in the dry season, soil respiration was significantly and negatively correlated with NO3--N and urease, but was significantly and negatively correlated with peroxidase, polyphenol oxidase, microbial population, MBC, and MBN. 【Conclusion】 HN suppressed soil respiration in P. yunnanensis forests over time, and N application did not change the seasonal and daily patterns of soil respiration.