中亚热带山区深层土壤有机碳库对土地利用变化的响应

Abstract

PDF HTML阅读 XML下载 导出引用 引用提醒 中亚热带山区深层土壤有机碳库对土地利用变化的响应 DOI: 10.5846/stxb201310312630 作者: 作者单位: 湖南农业大学资源环境学院,中国科学院亚热带农业生态研究所,湖南农业大学资源环境学院,湖南农业大学资源环境学院,湖南农业大学资源环境学院 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目(31100381);湖南省自然科学基金项目(13JJ4066);湖南农业大学引进人才项目(11YJ20) Response of deep soil organic carbon storage to land-use changes in subtropical hilly region of China Author: Affiliation: College of Resources Environment,Hunan Agricultural University,Key Laboratory of Agro-Ecological Processes in Subtropical Region,Institute of Subtropical Agriculture,Chinese Academy of Sciences,College of Resources Environment,Hunan Agricultural University,College of Resources Environment,Hunan Agricultural University,College of Resources Environment,Hunan Agricultural University Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:通过对中亚热带丘陵山区4种典型的土地利用方式(天然林以及由此转变而来的杉木人工林、板栗园和坡耕地)1 m深土壤剖面碳储量、δ13C值和细根生物量的研究,结果表明:土地利用变化7a后,土壤剖面(1 m)有机碳储量与天然林相比降低了26%-36%,且40 cm以下深层矿质土壤碳储量下降了19%-45%。1 m深土壤δ13C平均则升高1‰-3‰,说明植物群落的光合类型发生了变化,C4植物种对土壤有机碳的贡献增加。天然林转变后,严重的水土流失、人为扰动和植物物种组成的变化,诱发深层土壤碳输入减少以及碳流失和矿化损失增加,是导致深层土壤碳储量大幅下降的主因。土地利用变化后,60 cm深细根生物量锐减50%-99%,且细根主要集中于表土层。这主要与土壤理化性状劣化、资源有效性大幅降低及天然林转变后植被幼龄化有关,反映土地利用变化后土地生产力大幅退化。上述研究结果揭示在中亚热带山地开发、利用和土地转变过程中,加强天然林保育和中幼林抚育,创新减轻坡土扰动的农艺措施和加强陡坡地退耕,严控水土流失,科学施肥补充损失的土壤有机质和养分,对于维系山地土壤生产力和山区可持续经营具有长远意义。 Abstract:Soil is a major terrestrial carbon pool and most of the soil carbon is stored in the deep soil layers, which contributes to more than half of the total soil carbon storage. Compared with the topsoil carbon storage, carbon reserved in deep soil depth may respond differently to environmental change and land management practices. Thus, it needs to consider the deep soil organic carbon storage in the global carbon cycles. In the subtropical hilly region of China, some soils are deeply weathered and have highly developed profile. These deeply weathered soils may very sensitive to land use changes. Until recently, the dynamics of carbon storage in deep soil, especially its response to land use conversion was largely ignored in the subtropical hilly region of China. In the present study, soil carbon storage at 1 m depth, soil δ13C value and fine root biomass were evaluated within a representative land-use sequence in mid-subtropical China. The purpose was to evaluate the effect of land use change on the storage and resource of deep soil carbon storage. The land-use tpes included natural forest (control treatment), Chinese fir plantation, Chinese chestnut orchard and sloping tillage. Results showed that soil carbon storage at 1 m depth was 112.03, 82.40, 78.83 and 72.29 t/hm2 for natural forest, Chinese fir plantation, Chinese chestnut orchard and sloping tillage, respectively. After the natural forest was converted to other land uses for 7 years, soil carbon storage was decreased by 26%-36% at 1 m depth. Not only the topsoil (27%-34%), but also the deep soil (below 40 cm) showed significant decrease of carbon storage by 19%-45%. The conversion from natural forest to sloping tillage exerted a larger decrease of soil carbon storage than to Chinese fir plantation and Chinese chestnut orchard. In contrast to the decrease of soil carbon storage with land use changes, the average δ13C value at 1 m depth was increased by 1‰-3‰, indicating an increasing contribution of carbon input from C4 plant species to soil. After the land-use conversion, severe human disturbance caused serious topsoil erosion and water loss and shift of plant species composition. This led to the reduction of carbon input to soil and the increment of carbon loss in deep soil, and further to a substantial decrease of deep soil carbon storage. In addition, the fine root biomass at 60 cm depth was reduced by 50%-99% and tended to concentrate in surface soil layer after the land-use changes. It was primarily due to the deterioration of soil physicochemical regime, decrease of available soil resource and juvenile vegetation after the land use conversion. The decrease of fine root biomass also reflected a substantial degradation of land productivity. In conclusion, our study raises concerns about (i) the importance of natural forest preservation and young forest nurture; (ii) innovation of agronomic soil practices as regarding to topsoil disturbance reduction and continue implementation of "grain for green" policy in sloping tillage; and (iii) controlling of topsoil erosion and water loss and supplement of chemical fertilizer after the land-use conversion in hilly region of middle subtropical China. 参考文献 相似文献 引证文献