种植米槠、杉木土壤DOM浓度和光谱特征差异及其对短期增温的响应

Differences in Soil DOM Concentration and Spectral Characteristics of Castanopsis Carlesii and Cunninghamia Lanceolata and Their Response to Short-term Warming

摘要:

为揭示不同树种土壤可溶性有机质(Dissolved organic matter，DOM)对全球变暖的响应，在福建三明森林生态系统国家野外科学观测研究站采用根箱增温法，选取亚热带地区代表性植物幼苗米槠(Castanopsis carlesii.CC)、杉木(Cunninghamia lanceolata，CL)为研究对象，设置未种树作为对照处理，结合紫外可见光谱和荧光光谱分析，探究短期增温对种植米槠、杉木土壤DOM浓度和光谱特征的影响。结果表明：①种植不同树种的土壤可溶性有机碳(Dissolved organic carbon，DOC)含量存在显著差异，其中种植杉木处理显著高于米槠和未种树处理；树种对根箱土壤DOM荧光指数(Fluorescence index，FluI)、生物源指数(Biological index，BIX)和腐殖化指数(Humification index，HIX)均无显著影响，但米槠根箱土壤DOM芳香性(SUVA₂₅₄)、疏水性(SUVA₂₆₀)均高于杉木根箱和未种树处理；②短期增温对种植不同树种根箱土壤DOC含量无显著影响，也未显著影响DOM的SUVA₂₅₄、SUVA₂₆₀、分子量大小(SUVA₂₈₀)、BIX和HIX，但短期增温显著增加了种树根箱土壤DOM的FluI、溶解性微生物副产物组分的相对贡献率；③冗余分析和结构方程模型均表明，增温通过调节根系生长、土壤养分和土壤微生物生物量，对土壤DOM浓度及光谱特征产生不同程度的影响。总体上不同树种土壤DOM浓度及光谱特征对短期增温响应不明显，但短期增温后种植米槠、杉木土壤的DOM结构复杂性降低，微生物活动代谢来源增加。本研究可为理解亚热带区域森林土壤DOM的含量及组成提供基础数据，也可为全球气候变暖背景下造林树种选择提供一定的参考。

Abstract:

In order to reveal soil dissolved organic matter (DOM) responses of different tree species to global warming, soil warming of root-boxes were employed at the Forest Ecosystem National Observation and Research Station in Sanming, Fujian. The representative plant seedlings of Castanopsis carlesii (CC) and Cunninghamia lanceolata (CL) in subtropical areas were selected as the research objects, and no tree was set as the control (NT). Uv-vis spectrum and fluorescence spectrum analysis were used to explore the effects of short-term warming on soil DOM concentrations and spectral characteristics. The results showed that, 1) Soil DOC concentrations were significantly different under different tree species, which was significantly higher under CL than that under CC and NT. Tree species had no significant effects on soil DOM fluorescence index (FluI), biological index (BIX) and humification index (HIX), but soil DOM aromaticity (SUVA₂₅₄) and hydrophobicity (SUVA₂₆₀) were higher under CC than those of CL and NT. 2) Short-term warming had no significant effect on soil DOC concentration under different tree species, and did not significantly affect the SUVA₂₅₄, SUVA₂₆₀, molecular weight (SUVA₂₈₀), BIX and HIX, but short-term warming significantly increased FluI of soil DOM and the relative contribution of dissolved microbial by-product components. 3) RDA and SEM analyses both showed that soil warming affected soil DOM concentration and spectral characteristics to varying degrees by regulating root growth, soil nutrients and microbial biomass. In conclusion, short-term warming insignificantly affects soil DOM concentrations and spectral characteristics under different tree species, but decreases the complexity of soil DOM structure and increases the metabolism sources of microbial activity. This study provides basic data for understanding the concentration and composition of forest soil DOM in subtropical region, and also provides certain reference for tree species selection under global warming.