| 不同土地利用方式对岩溶区土壤有机碳组分稳定性的影响 |
| 摘要点击 785 全文点击 209 投稿时间：2023-02-18 修订日期：2023-03-17 |
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| 中文关键词 岩溶区 土地利用 惰性有机碳 土壤有机碳稳定性 结构方程模型 |
| 英文关键词 karst area land use recalcitrant organic carbon soil organic carbon stability structural equation models |
| 作者 | 单位 | E-mail | | 陈坚淇 | 西南大学地理科学学院, 岩溶环境重庆市重点实验室, 重庆 400715 | 1124336628@qq.com | | 贾亚男 | 西南大学地理科学学院, 岩溶环境重庆市重点实验室, 重庆 400715 | jiayanan@swu.edu.cn | | 贺秋芳 | 西南大学地理科学学院, 岩溶环境重庆市重点实验室, 重庆 400715 | | | 江可 | 西南大学地理科学学院, 岩溶环境重庆市重点实验室, 重庆 400715 | | | 陈畅 | 西南大学地理科学学院, 岩溶环境重庆市重点实验室, 重庆 400715 | | | 叶凯 | 西南大学地理科学学院, 岩溶环境重庆市重点实验室, 重庆 400715 | |
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| 中文摘要 |
| 土壤有机碳的组分及其稳定机制是深入了解陆地碳汇能力的关键,岩溶生态系统中土壤有机碳稳定性在很大程度上影响土壤固碳能力.为了解人类活动对岩溶区土壤有机碳稳定性的影响,选取重庆市中梁山岩溶槽谷区为例,分层采集了4种典型土地利用方式（混交林、竹林地、荒草地和耕地）的土壤样本,分析不同土地利用方式下总有机碳（TOC）、重组有机碳（HFOC）、轻组有机碳（LFOC）、活性有机碳（LOC）、惰性有机碳（ROC）的分布特征,运用结构方程模型定量分析土地利用方式对土壤有机碳组成的影响及其稳定性的影响,为岩溶区土壤碳汇评估和土壤质量保护提供基础数据.结果表明：岩溶区不同土地利用方式下的各有机碳组分均出现明显的表聚现象,表层有机碳组分含量是底层的1.2倍；应用土壤惰性有机碳指数（ROCI）指示土壤有机碳稳定性,其变化区间为33.9%~64.5%,其中混交林最高为64.5%~66.3%,耕地最低为33.8%~39.6%.岩溶区惰性有机碳含量和ROCI表明,人类农业耕作活动引起土壤有机碳含量减少和土壤物理结构被破坏,导致土壤有机质分解和周转速率加快；影响岩溶区土壤稳定性的最重要因素是土壤pH,耕作活动引起土壤pH降低,减少了土壤微生物活性,不利于土壤中惰性有机碳和土壤有机碳库的积累. |
| 英文摘要 |
| The composition of soil organic carbon and its stability mechanism are the key to understanding the terrestrial carbon sink capacity. The stability of soil organic carbon in a karst ecosystem greatly affects the soil carbon fixation capacity. In order to understand the impact of human activities on the stability of soil organic carbon in karst areas, the karst valley area of Zhongliang Mountain in Chongqing was selected as an example, and soil samples of four typical land use modes (mixed forest, bamboo forest, grassland, and cultivated land) were collected in layers to analyze the total organic carbon (TOC) and heavy fraction organic carbon (HFOC). The distribution characteristics of light fraction organic carbon (LFOC), labile organic carbon (LOC), and recalcitrant organic carbon (ROC) were analyzed quantitatively by using a structural equation model to provide basic data for soil carbon sink assessment and soil quality protection in karst areas. The results showed that the organic carbon components under different land use patterns in karst areas had obvious surface accumulation, and the content of organic carbon components in the surface layer was 1.2 times that in the bottom layer. Except for LFOC, the content of other organic carbon components was the highest in the mixed forest, followed by that in the bamboo forest and wasteland, with the lowest in cultivated land. Mixed forest ω(TOC) content was the highest, 42.5 g·kg-1, followed by that of bamboo forest (36.6 g·kg-1) and grassland (18.7 g·kg-1), and cultivated land content was the lowest, 13.4 g·kg-1. The soil organic carbon content of cultivated land was 68.5%, 63.5%, and 28.3% lower than that of mixed forest, bamboo forest, and grassland, respectively. Mixed forest had the highest content of ω(HFOC), 21 g·kg-1, followed by those of bamboo forest (20.9 g·kg-1), grassland (18.2 g·kg-1), and cultivated land (13.5 g·kg-1). The mixed forest ω(LOC) content was the highest, 16.3 g·kg-1, followed by those of bamboo forest (14.9 g·kg-1), grassland (11.5 g·kg-1), and cultivated land (5.3 g·kg-1). Mixed forest ω (ROC) content was the highest, 25.7 g·kg-1, followed by those of bamboo forest (21.6 g·kg-1), grassland (15.9 g·kg-1), and cultivated land (10.3 g·kg-1). The bamboo forest land ω(LFOC) content was 15.9 g·kg-1, followed by those of mixed forest (13.9 g·kg-1), grassland (7.3 g·kg-1), and cultivated land (4.9 g·kg-1). The recalcitrant organic carbon index (ROCI) was used to indicate the stability of soil organic carbon. The variation range of ROCI was 33.9%-64.5%, of which the highest was mixed forest (64.5%-66.3%), and the lowest was cultivated land (33.8%-39.6%). The ROCI of mixed forest, bamboo forest, and grassland were 1.8 times, 1.6 times, and 1.4 times that of cultivated land, respectively. Karst area ω (inert organic carbon) content and ROCI showed that human agricultural activities caused the reduction in soil organic carbon content and the destruction of soil physical structure, resulting in the accelerated decomposition and turnover rate of soil organic matter. The most important factor affecting soil stability in karst areas was soil pH. Tillage activities caused soil pH to rise, reduced soil microbial activity, and were not conducive to the accumulation of the inert organic carbon and soil organic carbon pool in the soil. |
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