宁南黄土丘陵区不同生态恢复模式对土壤养分的影响

[目的]分析植被恢复过程中土壤养分的变化规律,认识和评价植被生态系统功能恢复,促进植被演替和加快生态恢复的人工调控。[方法]通过对宁夏南部山区彭阳县中庄示范区天然草地(封山禁牧)、农耕地(退耕)、人工苜蓿(退耕还林草)3种生态恢复模式进行调查,研究分析不同生态恢复模式对土壤养分的影响。[结果]宁夏黄土丘陵区不同生态恢复模式效果依次为:天然草地农耕地人工苜蓿。随着土层深度的增加,土壤养分含量均呈现降低的趋势。随着植被恢复年限的延伸,土壤养分会逐渐累积而增加。不同恢复年限苜蓿地土壤肥力指数小于农耕地,土壤肥力贫瘠,且随苜蓿种植时间的延长,呈现先增大,再减小的趋势。[结论]在宁夏黄土丘陵区进行植被恢复,能明显提高土壤养分含量,改善土壤肥力状况,但旱作苜蓿粗放经营(只刈割,不培肥),导致土壤综合肥力指数日趋下降。

Effects of Soil Nutrients on Ecological Restoration Patterns in Loess Hilly Region of Southern Ningxia Hui Autonomous Region

[Objective] The objectives of the study are to analyze the changes in soil nutrients with vegetation recovery in order to understand and evaluate the functional restoration of vegetation ecosystem, and to adjust speed the vegetation succession and accelerate the ecological recovery.[Methods] Three ecological restoration patterns, natural grassland(grazing forbidden), farmland(fallow) and planted alfalfa(returning to forest and grassland), were investigated to analyze the influence of ecological restoration on soil nutrients.[Results] The natural grassland has bigger effects than farmland then followed by planted alfalfa on soil. As the soil depth increased, all soil nutrients decreased. With the time of recovery, soil nutrients gradually accumulated. The soil fertility index in alfalfa fields was lower than that in farmland and increased in the early period of recovery and then declined with time.[Conclusion] Vegetation recovery in the loess hilly region in Ningxia would obviously increase the contents of soil nutrients and improve the fertility of soil. But alfalfa, which was extensively managed on dry fields(no fertilizer applied but only mowing), would seriously decrease soil fertility.