基于GWR模型的伊河流域土壤有机碳空间分布特征及影响因素分析

土壤有机碳作为陆地碳库主体，其分布特征及与驱动因素的空间关系对土壤碳周转过程有重大影响。通过野外调查、采样和室内分析，基于地理加权回归（GWR）模型结合9个环境和土壤变量，建模分析伊河流域土壤有机碳空间分布状况，以及影响其分布的主要因素。研究发现，流域表层土壤有机碳在3.37-38.34 g/kg之间，上、中、下游有机碳分布存在空间差异，其中上游差异最大，下游差异最小。相关分析表明，有机碳与土壤理化性质相关性显著，与年平均气温以外的环境因子相关性不显著。GWR模型较好地预测了伊河流域土壤有机碳空间分布，局部决定系数在0.49-0.64之间，自下游到上游，决定系数逐步升高，对上游的预测精度最高。分析发现，在海拔较高的中上游区域，土壤有机碳含量主要受立地环境、成土母质和地表覆盖的影响；在中上游低山丘陵区，人类活动和环境因素共同影响了土壤有机碳含量；在中下游平原区农业活动和化肥投入是造成土壤有机碳含量较高的主要因素。研究揭示了各因素对有机碳影响的空间分异特征，可为伊河流域土壤生态系统的合理发展和管理提供依据。

Spatial distribution characteristics and influencing factors of soil organic carbon in Yihe River Basin based on GWR model

Soil organic carbon (SOC), as the main body of land carbon pool, its distribution characteristics and spatial relationship with driving factors have significant impacts on the process of soil carbon turnover. Through field investigation, sampling and indoor analysis, based on the geographical weighted regression (GWR) model combined with nine environmental and soil variables, the spatial distribution of soil organic carbon and its main affecting factors in the Yihe River Basin were analyzed. The results showed that:(1) the distribution of organic carbon in the surface soil was between 3.37-38.34 g/kg. There were spatial differences in the upper, middle, and lower reaches, among which the difference in the upper reaches was the largest and the difference in the lower reaches was the smallest. (2) Soil organic carbon was closely related to the physical and chemical properties of soil itself, and was less affected by environmental factors other than annual average temperature. (3) The GWR model can predict the spatial distribution of soil organic carbon in the Yihe River Basin, and the local determination coefficient was between 0.49-0.64. From the downstream to the upstream, the determination coefficient increased gradually, and the prediction accuracy of the upstream was the highest. (4) In the middle and upper reaches of high altitude, soil organic carbon contents were mainly affected by site environment, soil parent material, and surface coverage. In the middle and upper reaches of low mountains and hills, human activities and environmental factors jointly affected soil organic carbon content. In the middle and lower reaches of plain area, the agricultural activities and chemical fertilizer input were the main factors causing high soil organic carbon content. This study revealed the spatial differentiation characteristics of the effects of various factors on organic carbon, which could provide a basis for the reasonable development and management of soil ecosystem in the Yihe River Basin.