喀斯特山地不同微地貌下土壤碳氮磷空间异质性及生态化学计量特征

Spatial heterogeneity and ecological stoichiometry characteristics of soil carbon,nitrogen and phosphorus under different micro-geomorphology in karst mountains

喀斯特地区特殊地质背景造就复杂破碎的地形发育出多样的微地貌,这使得清晰地认识土壤碳氮磷的空间异质性及生态化学计量特征存在困难。基于实地调查、土壤采样、实验测试的结果数据,引入混合效应模型评估方法结合变异系数,分别从全量(土壤有机碳、全氮、全磷)及有效态(活性有机碳、碱解氮及速效磷)两方面,揭示不同微地貌类型下土壤碳氮磷空间异质性及其生态化学计量特征。结果显示:(1)不同微地貌类型下土壤有机碳、全氮、全磷对碳氮磷比值的耦合解释度为:土面(91.09%)>石沟(91.02%)>石坑(84.63%)>石洞(80.17%)>石缝(73.20%),土面的空间异质性最低而石缝最高。(2)有效态方面,活性有机碳、碱解氮和速效磷对碳氮磷比值的耦合解释度特征为:石缝(84%)>石洞(58.15%)>土面(47.80%)>石坑(44.06%)>石沟(32.18%),说明石缝微地貌的土壤活性有机碳、碱解氮及速效磷空间异质性最低。(3)不同微地貌类型下土壤全量碳氮磷生态化学计量的变异系数差异均在50%以上(C/N 80%、C/P 53.57%、N/P 69.33%)。通过揭示不同微地貌土壤全量及有效态碳氮磷空间异质性及生态化学计量特征,为喀斯特土壤系统管理方案及应对全球变化与碳中和提供数据和科学参考。

The specially geological background of karst area has created complex and broken topography and developed various micro-geomorphology,which made it difficult for people to clearly understand the spatial heterogeneity and ecological stoichiometry characteristics of soil carbon,nitrogen and phosphorus.On the basis of field investigation,soil sampling and test results,the mixed effect model evaluation method combining coefficient of variation was introduced,and the spatial heterogeneity of soil carbon,nitrogen and phosphorus under different micro-geomorphic types and their eco-chemical measurement characteristics were revealed from two aspects:total amount(soil organic carbon,total nitrogen and total phosphorus)and effective amount(active organic carbon,available nitrogen and available phosphorus).The results show that:(1)The coupling interpretation degree of soil organic carbon,total nitrogen and total phosphorus to the ratio of carbon,nitrogen and phosphorus under different micro-geomorphic types is:earth flatland(91.09%)>gully(91.02%)>pit(84.63%)>stone cavern(80.17%)>crevice(73.20%),with the lowest spatial heterogeneity of soil surface and the highest stone crevice.(2)In terms of available state,the coupling explanation degree of active organic carbon,available nitrogen,available phosphorus and the ratio of carbon,nitrogen and phosphorus is characterized as followed:crevice(84%)>stone cavern(58.15%)>earth flatland(47.80%)>pit(44.06%)>gully(32.18%),which indicates that the spatial heterogeneity of soil active organic carbon,available nitrogen and available phosphorus in stone crevice micro-topography is the lowest.(3)The coefficient of variation of ecological stoichiometry of total soil carbon,nitrogen and phosphorus under different micro-geomorphic types are all above 50%(C/N 80%,C/P 53.57%,and N/P 69.33%).By revealing the spatial heterogeneity of total and available carbon,nitrogen and phosphorus in different micro-geomorphic soils and the characteristics of eco-chemistry,we can provide data and scientific reference for karst soil system management scheme and coping with global change and carbon neutralization.