暖温带森林土壤有机碳含量和碳储量的海拔梯度格局及环境解释

Elevational patterns and environmental drivers of soil organic carbon content and storage in a warm-temperate forest

研究气候过渡区森林土壤有机碳沿环境梯度的分布格局对预测气候变化背景下土壤有机碳动态有重要意义。为揭示亚热带向暖温带气候过渡地带森林土壤有机碳含量及碳储量沿海拔变化趋势,本研究在山西历山国家级自然保护区海拔890~2200 m范围内,以每100 m高差段为取样区间,沿海拔设置了15个森林固定监测样地。采用五点取样法,结合植物多样性、土壤理化性质、土壤微生物和气候因子的海拔变化特征,分析土壤有机碳含量及碳储量(0~10 cm)垂直分布特征及各环境因子的相对贡献。结果表明:土壤有机碳含量及碳储量均随海拔升高显著变化,总体呈现先下降再上升的U型趋势。土壤有机碳含量在1645 m海拔处最大(75.41±14.05 g·kg^(-1)),而土壤有机碳储量在894 m处最大(51.85±9.89 Mg·hm^(-2))。Mantel检验表明,土壤有机碳含量与土壤、气候因子以及微生物物种丰富度存在显著相关性,而土壤有机碳储量空间变化仅与土壤因子和土壤微生物物种丰富度显著相关。环境因子分别解释土壤有机碳含量和碳储量海拔变化64.7%和33.9%的总变异。年降水量是影响土壤有机碳含量变化的首要因素(14.8%),其次是土壤硝态氮(13.4%)和年均气温(13.2%)。土壤全磷是土壤有机碳储量沿海拔变化中贡献最大的环境因子,重要性占比超过15%,其次是土壤硝态氮(8.7%)和年均气温(7.5%)。本研究对评估气候过渡带森林土壤有机碳储量及其变化特征具有重要的参考价值。

College of Forestry,Shanxi Agricultural University;Shanxi Lishan National Nature Reserve Management Bureau;Exploring soil organic carbon(SOC)changes along environmental gradients in climate transition zone is essential for predicting soil organic carbon dynamics under climate change.To understand the spatial variations of SOC content and storage in the transition zone of subtropical to warm-temperate climate,15 monitoring forest plots were set up in Lishan National Nature Reserve in Shanxi Province along an elevation gradient from 890 m to 2200 m above sea level at a 100 m interval.We assessed the elevational changes in SOC content and storage and their relationships with plant diversity,soil physicochemical and climatic factors,and microbial characteristics by using five-point sampling method.The results showed that both SOC content and storage showed overall U-shaped trends along the elevational gradient.The SOC content and storage peaked at 1645 m(75.41±14.05 g·kg^(-1))and 894 m(51.85±9.89 Mg·hm^(-2)),respectively.Results of the Mantel test showed that SOC content was significantly correlated with soil factors,climatic factors,and microbial species richness,while the spatial variation in SOC storage was only significantly correlated with soil factors and microbial species richness.Environmental factors explained 64.7%and 33.9%of the total variations of elevational patterns in soil SOC content and storage,respectively.Annual precipitation was the largest predictor(14.8%of total explained variance)for SOC content,followed by NO_(3)^(-)-N(13.4%)and annual mean temperature(13.2%).For SOC storage,soil total phosphorus had the strongest effect with over 15%of total explained variance,followed by NO_(3)^(-)-N(8.7%)and annual mean temperature(7.5%).This study provides an important reference for evaluating soil organic carbon storage and its variation in forests in the climatic transition zone.