风沙黄土区排土场不同植被类型下土壤生态化学计量特征

Soil Ecological Stoichiometric Characteristics Under Different Vegetation Types of Open-Pit Dump in Sandy Loess Region

[目的]准确评价风沙黄土区露天矿区排土场不同植被类型下土壤改良效益,并揭示其植被恢复的养分限制性,进而为该区生态重建与环境改善构建高效的植被恢复模式提供理论依据。[方法]选取鄂尔多斯武家塔排土场乔、灌、草3种植被类型的10种恢复模式的土壤为研究对象,以新排土为对照,开展其土壤有机碳、全氮和全磷与其化学计量特征及关系的研究。[结果]风沙黄土区排土场土壤有机碳、全氮、全磷含量变化分别为0.62~18.60 g/kg, 0.09~0.36 g/kg和0.04~0.21 g/kg,其中乔、灌林地的土壤有机碳、全氮养分含量显著高于新排土(p≤0.05),乔木林地的全磷含量显著低于其他3种样地(p≤0.05);在土层垂直剖面,3种植被类型的土壤养分均表现为表层富集性,灌木林地的土壤全氮含量在不同土层均表现最高,乔木林地土壤有机碳平均含量最高,草地的全磷平均含量最多。土壤C/N在不同植被类型间无显著差异(p>0.05),土壤C/P和N/P受植被类型的影响较大,均表现为乔木林地>灌木林地>草地>新排土;在土层垂直剖面,C/N整体呈现增大的变化趋势,N/P先减小后增大的趋势。土壤有机碳与C/N,C/P,N/P均呈极显著正相关关系(p≤0.01);土壤全氮与C/P,N/P呈极显著正相关关系(p≤0.01),土壤全磷则反之。乔木林地土壤N/P较高,植被生长受磷含量的限制;草地、灌木林地土壤N/P较低,植被生长受氮含量的限制。[结论]在植被恢复初期先种植草灌改善土壤表层养分,并适当施加氮肥,随着土壤肥力的提高再逐步种植乔木,配施磷肥以增强复垦效果。

[Objective]This study aimes to accurately evaluate the soil improvement benefits and to reveal the nutrient limitations under different vegetation types in the open-pit dump in the sandy loess area,so as to provide a theoretical basis to construct an efficient vegetation restoration model for ecological reconstruction and environmental improvement in this area.[Methods]The soils from ten kinds of vegetation restoration modes,belonging to three vegetation types of forest,shrub,and grass were selected as study samples,while the soil from the newly dumped land was selected as control.The ecological stoichiometric characteristics of soil organic carbon,total nitrogen and total phosphorus and their relationships were studied.[Results]The values of soil organic carbon,total nitrogen,and total phosphorus for soil under different vegetation types of dump in sandy loess region varied between 0.62~18.60 g/kg,0.09~0.36 g/kg and 0.04~0.21 g/kg,respectively.The values of soil organic carbon and total nitrogen in the forest land and shrub land were significantly greater than those in the newly dumped land(p≤0.05),and the values of total phosphorus in the arboreal land were significantly lower than those in the other three plots(p≤0.05).In the vertical section of soil layer,the soil nutrients of three types of planting cover enriched in the surface layer.The soil total nitrogen amount of shrub land was the highest in different soil layers,the mean soil organic carbon amount of arbor land was the highest,and the mean soil total phosphorus amount of grass land was the highest.There was no significant difference in soil C/N among different vegetation types(p>0.05).Soil C/P and soil N/P were greatly affected by vegetation types,and all of them showed the order:new soil dumping of arbor land>shrub land>grass land>new dump.In the vertical section of soil layer,soil C/N showed the increasing trend overall,and soil N/P firstly decreased and then increased with the increase of soil layer depth.Soil organic carbon was significantly positively correlated with soil C/N,C/P and N/P(p≤0.01).Soil total nitrogen was significantly positively correlated with soil C/P and N/P(p≤0.01),while soil total phosphorus was on the contrary.Soil N/P in arbor land was high,and vegetation growth was limited by the phosphorus amount.Soil N/P in grass land and shrub land was low,and vegetation growth was limited by the nitrogen amount.[Conclusion]It is suggested that grass and shrub should be planted at the early stage of vegetation restoration to improve soil surface nutrients;furthermore,nitrogen fertilizer should be applied appropriately.With the improvement of soil fertility,trees should be gradually planted and phosphorus fertilizer should be applied to enhance the reclamation effect.