基于DNDC模型的甘南高寒草甸土壤总氮密度模拟研究

Simulation of soil total nitrogen density in alpine meadow of Gannan based on DNDC model

摘要:

【目的】 对土壤总氮密度进行模拟，探究1993-2022年甘南州高寒草甸近30年土壤总氮密度的变化规律及其影响因素。【方法】 采用克里金差值法分析土壤总氮密度的空间动态分布，利用单因素方差分析、相关分析和主成分分析方法探讨土壤总氮密度与不同土层、环境因素之间的相关关系及其影响因素。【结果】 甘南州高寒草甸土壤总氮密度30年间波动较大，2005年之前呈波动上升趋势， 2005年达到最大值92 410.05 kg/hm²，之后呈下降趋势。在空间分布上，由西向东逐渐减少。其中玛曲的总氮密度最高，其次是夏河和碌曲，最低的是迭部和舟曲。土壤总氮密度随土层深度的增加而逐渐降低，其中0~10 cm土层总氮密度呈增加趋势，由4 823.14 kg/hm²增加到5 093.29 kg/hm²，10~ 20 cm和20~30 cm土层总氮密度均有所减少，10~20 cm土层总氮密度由3 874.14 kg/ hm²减少到 3 699. 41 kg/hm²，20~30 cm土层总氮密度由2 845.59 kg/ hm²减少到2 725.41 kg/ hm²。【结论】 土壤总氮密度与不同土层之间呈显著正相关，且随着土层深度的增加而显著减小，各研究站点之间的年均温度存在显著差异，温度越高，土壤总氮密度越低，与年均降水量的相关性相反。海拔高度、有机碳含量和黏土比例与土壤总氮密度呈显著正相关，土壤容重、pH值和土壤含水量与土壤总氮密度呈负相关。该研究对生态系统的保护具有重要的意义，为甘南地区草地管理提供科学依据。

Abstract:

【Objective】 In this study，the soil total nitrogen density in alpine meadow in Gannan Prefecture was simulated from 1993-2022 based on the DNDC model with localized parameters. It aims to explore the variations and influencing factors of soil total nitrogen density over the past 30 years.【Method】 The Kriging difference method was used to analyze the spatial dynamic distribution of soil total nitrogen density. One - way analysis of variance （ANOVA），correlation analysis，and principal component analysis were used to investigatethe correlation between soil total nitrogen density and different soil layers，as well as various environmental factors.【Result】The total soil nitrogen density in the alpine meadows of Gannan Prefecture fluctuated greatly over the past 30 years，exhibiting a fluctuating upward trend until 2005，reaching a maximum of 92 410. 05 kg/hm2 in 2005，followed by a downward trend. In terms of spatial distribution，nitrogen density decreased from west to east. Among them，the highest total nitrogen density was observed in Maqu，followed by Xiahe and Luqu，with the lowest recorded value in Diebu and Zhouqu. The total nitrogen density of soil gradually decreased with the increase of soil depth. For the 0~10 cm soil layer，nitrogen density increased from 4 823. 14 kg/hm2 to 5 093. 29 kg/hm2，while the total nitrogen density of 10~20 cm and 20~30 cm soil layer decreased. Specifically，the total nitrogen density in the 10~20 cm soil layer decreased from 3 874. 14 kg/hm2 to 3 699.41 kg/hm2，and the total nitrogen density of the 20~30 cm soil layer decreased from 2 845. 59 kg/hm2 to 2 725.41 kg/hm2. One-way ANOVA and principal component analysis revealed that there were significant differences in soil total nitrogen density across different soil layers. The analysis also showed a significant relationship between nitrogen density and annual mean temperature，with higher temperatures associated with lower total nitrogen density within the soil. Additionally，soil nitrogen density was inversely correlated with annual mean precipitation. Correlation analysis indicated that there was a significant positive correlation between total nitrogen density and soil depth，with nitrogen density decreasing with increasing soil depth. Altitude，organic carbon content，and clay proportion were positively correlated with total nitrogen density，while soil bulk density，pH and soil water content were negatively correlated. This study offers valuable insights into the dynamic changes insoil total nitrogen density and provides a scientific basis for grassland management and grazing in the Gannan area，contributing to the protection of ecosystems.