载畜率对荒漠草原灌木及半灌木土壤养分的影响

Effects of different stocking rates on soil nutrients of shrub and semi-shrub in desert steppe

摘要:

【目的】研究不同载畜率下草原土壤退化机制及载畜率对不同灌木及半灌木土壤养分含量的影响 。【方法】以内蒙古自治区短花针茅荒漠草原的冷蒿（Artemisia frigida）、木地肤（Kochia prostrata）、小叶锦鸡儿（Caragana microphylla）和驼绒藜（Ceratoides latens）4 种灌木的土壤为研究对象，设置 4 个不同的载畜率水平，分别为对照区 CK（0 只/hm² ）、轻度放牧区 LG（0. 93 只/hm² ）、中度放牧区 MG（1. 82 只/hm² ）和重度放牧区 HG（2. 71 只/hm² ），在不同载畜率放牧小区，以选定植株为中心， 采用以 0. 25、0. 50、0. 75 和 1. 00 m 为半径的同心圆样方法，使用土钻钻取 0~10 cm 的土壤，测定其有机碳、碱解氮、速效磷等含量，并对各指标进行双因素方差分析（载畜率和采样距离）。【结果】冷蒿和小叶锦鸡儿的有机碳含量随着载畜率增加呈现下降趋势，木地肤和驼绒藜的有机碳含量随着载畜率增加呈先增大后减小的趋势（P＜0. 05）。在 LG 区，各个植物的土壤碱解氮含量均最低（P＜0. 05）。木地肤的土壤速效钾含量在各个处理之间最大（P＜0. 05）。土壤养分含量聚集在在距离灌木及半灌木 0. 5 m 内。【结论】荒漠草原不同灌木及半灌木的土壤养分随着载畜率和距离的变化而变化，土壤养分的含量聚集在距离灌木及半灌木 0. 5 m 内，研究灌木及半灌木土壤养分的变化，便于采取合理的放牧管理措施，促进草地畜牧业可持续发展。

Abstract:

【Objective】The investigation of dynamic changes in the soil nutrient content of dominant shrub popu- lations in the desert steppe is critical for elucidating the mechanism of grassland ecosystem stability.【Method】Stipa breviflora desert steppe was used as the research object，Inner Mongolia，to investigate the mechanism of grassland soil degradation under different stocking rates. The effect of stocking rate on the soil nutrient content of different shrubs and semi-shrubs was also studied in this paper.The soil of Artemisia frigida，Kochia prostrata，Caragana mi- crophylla and Ceratoides latens in Stipa breviflora desert steppe was taken as the research objects，and four different stocking rates were set (CK，0 sheep/hm² ; LG，0.93 sheep/hm² ; MG，1.82 sheep/hm² ; and HG，2.71 sheep/hm² ).The soil of the four main shrubs and semi-shrub communities was collected by soil drilling in grazing plots with different stocking rates. The contents of organic carbon，alkali-hydrolyzable nitrogen，and available phosphorus were deter- mined in the laboratory，and the two-factor variance analysis was performed on each index.【Result】 The results showed that the organic carbon content of A.frigida and C.microphylla showed a downward trend with the increase of stocking rate，and the organic carbon content of K.prostrata and C.latens showed a trend of first increase and then decrease with the increase of stocking rate(P＜0.05).In the LG plot，soil alkali-hydrolyzed nitrogen content of all plants was the lowest (P＜0.05).The content of available potassium in soil of Kochia prostrata was the highest among all treatments(P＜0.05). The soil nutrient content was concentrated within 0.5 m from shrubs and semi-shrubs. 【Conclusion】 The soil nutrients of different shrubs and semi-shrubs change with changes in stocking rate and distance in desert steppe. The soil nutrient content was concentrated within 0.5 m from shrubs and semi - shrubs. The study aims to investigate the changes in soil nutrients of shrubs and semi-shrubs in order to adopt reasonable grazing man- agement measures and promote the sustainable development of grassland animal husbandr.