滇中退化山地不同植被恢复下土壤碳氮磷储量与生态化学计量特征

植被恢复对土壤营养元素的存赋及其生态化学计量特征的影响广受关注,为了深入了解不同植被恢复类型下土壤碳、氮、磷储量与生态化学计量特征,选择滇中地区退化山地飒马场流域具有代表性的4种不同修复阶段的典型植被(荒坡灌草丛、云南松林、针阔混交林和次生常绿阔叶林)为研究对象,分析了不同植被类型下不同深度土壤中有机碳(SOC)、全氮(TN)、全磷(TP)储量和化学计量变化特征。结果表明,退化山地的植被恢复显著改变土壤碳氮磷储存能力和化学计量比,这种改变作用整体上随土壤深度增加而降低。其中,在0—60 cm土层上,SOC储量在次生常绿阔叶林最高,达123.41 t/hm~2,其次是针阔混交林(115.69 t/hm~2)和云南松林(93.08 t/hm~2),荒坡灌草丛(89.56 t/hm~2)最低;TN储量针阔混交林(4.91 t/hm~2)次生常绿阔叶林(4.58 t/hm~2)云南松林(4.43 t/hm~2)荒坡灌草丛(3.98 t/hm~2),4种植被类型间差异显著;TP储量云南松林最高(2.57 t/hm~2),次生常绿阔叶林(2.2 t/hm~2)最低;4种植被类型下土壤C/N介于15.77—30.18,C/P介于29.24—65.33,N/P介于1.28—2.68之间,在0—60 cm土层上均以次生常绿阔叶林最高。植被类型和土壤深度及其交互作用显著影响研究区的SOC、TN和TP储量和化学计量比。分析认为,退化山地不同植被类型对土壤碳氮磷储量和化学计量的影响过程复杂,修复演替进入到次生常绿阔叶林阶段土壤理化性质显著提升,该地区植被修复主要受到氮的限制。研究表征了滇中退化环境植被恢复过程中土壤主要元素变化特征,为揭示植被恢复与土壤生态功能演变关系提供数据支持。

Soil carbon, nitrogen and phosphorus stocks and ecological stoichiometry characteristics of different vegetation restorations in degraded mountainous area of central Yunnan, China

The effects of vegetation restoration on soil nutrient elements and their ecological stoichiometry are receiving increasing attention. In order to understand the characteristics of soil carbon, nitrogen, phosphorus storage and eco-chemical stoichiometry under different types of restoration, four representative restoration stages in Samachang watershed in the degraded mountainous area of central Yunnan, China were selected among typical vegetation(shrubland, yunnan pine forests, mixed coniferous and broad-leaved forests, and secondary evergreen broad-leaved forests), and the changes of soil organic carbon(SOC), total nitrogen(TN), total phosphorus(TP)stocks and stoichiometry in soils with different soil depths were analyzed under different vegetation types. The results showed that the types of vegetation restoration have significant effects on soil SOC, TN, TP stocks and stoichiometric ratios. Vegetation restoration significantly changes soil carbon, nitrogen, and phosphorus storage capacity and stoichiometry, and overall decreases with increasing depth. At 0-60 cm of soil, organic carbon stocks are the highest in secondary evergreen broad-leaved forests, reaching 123.41 t/hm², followed by mixed coniferous and broad-leaved forests(115.69 t/hm²)and Yunnan pine forests(93.08 t/hm²), and shrubland(89.56 t/hm²)is the lowest. Total nitrogen stocks are in the order of mixed coniferous and broad-leaved forests(4.91 t/hm²) > secondary evergreen broad-leaved forests(4.58 t/hm²) > Yunnan pine forests(4.43 t/hm²) > shrubland(3.98 t/hm²). There are significant differences of TN stocks among 4 vegetation types. Total phosphorus stocks in yunnan pine forests are the highest(2.57 t/hm²), and the secondary evergreen broad-leaved forest(2.2 t/hm²)presents the lowest value. The soil C/N under the 4 types of plant cover varies from 15.77 to 30.18, C/P ranging from 29.24 to 65.33, and N/P ranging from 1.28 to 2.68. The secondary evergreen broad-leaved forests shows the highest on the 0-60 cm soil layers. The analysis showed that the influence of different vegetation types on soil carbon, nitrogen, and phosphorus storage and stoichiometry is a complex ecological process. Vegetation restoration significantly changes soil carbon, nitrogen, and phosphorus storage capacity and stoichiometry, but the overall trends go down with the increasing soil depth, and the best physical and chemical properties of soil are represented in the secondary evergreen broad-leaved forests. The growth of vegetation in this area is mainly restricted by nitrogen shortage. The results of this study characterize the features of soil major element changes in the process of vegetation restoration in the degraded mountainous area of central Yunnan, and contribute informative support for revealing the relationship between vegetation restoration and soil ecological function evolution.