载畜率对短花针茅荒漠草原灌木及其邻近土壤养分含量的影响

Effect of stocking rate on the shrubs and their adjacent soil nutrients in Stipa breviflora desert steppe

草地灌丛化现象在草地生态系统上广泛发生。放牧是人类利用草原的重要方式,通过分析不同载畜率下荒漠草原灌木种群及其邻近土壤养分含量的变化,可研究放牧干扰下不同灌木种群的耐牧特性,对深入了解荒漠草原植物群落演替机制具有重要意义。以荒漠草原灌木小叶锦鸡儿(Caragana microphylla)、半灌木驼绒藜(Ceratoides latens)及小半灌木冷蒿(Artemisia frigida)和木地肤(Kochia prostrata)(下称为“灌木”)为研究对象,探究不同载畜率下各个灌木种群的密度、高度、盖度及地上生物量(下称为“数量特征值”)及其邻近土壤养分含量。结果表明:冷蒿的数量特征值均随着载畜率的增加而降低,其他植物种群的数量特征值均在CK或LG区出现最大值,且不同灌木邻近土壤养分含量随着土壤深度的增加而下降(P<0.05)。不同灌木邻近土壤全氮含量随着载畜率增加而下降;冷蒿邻近有机碳含量在CK区最高,小叶锦鸡儿邻近速效磷含量在HG区最高,其余灌木邻近有机碳、速效磷含量在LG区最高。灌木种群数量特征与土壤养分的关系为:土壤有机碳与冷蒿和驼绒藜的高度、盖度、地上生物量呈正相关,土壤速效磷与木地肤高度、地上生物量呈显著负相关。因此,载畜率均会对灌木植物种群的数量特征值及其邻近土壤养分含量产生影响。

Shrub encroachment is widespread in grassland ecosystems.Grazing is an important way for human beings to use grassland.By analyzing the changes of shrub populations and their adjacent soil nutrient contents in desert steppe under different stocking rates,the grazing tolerance characteristics of different shrub populations under grazing disturbance can be studied,which is of great significance for understanding the succession mechanism of plant communities in desert steppe.In this paper,Caragana microphylla,Ceratoides latens,Artemisia frigida and Kochia prostrata(hereinafter referred to as “shrub”) were used as the research objects to explore the density,height,coverage and aboveground biomass(hereinafter referred to as “quantitative characteristic value”) of each plant population under different stocking rates and its adjacent soil nutrients.The results showed that the quantitative characteristics of A.frigida decreased with the increase of stocking rate,the quantitative characteristics of other plant populations showed the maximum value in No grazing or Light grazing treatment,and the soil nutrient content adjacent different shrubs decreased with the increase of soil depth(P<0.05).The total nitrogen content adjacent different shrubs decreased with the increase of stocking rate.The organic carbon content adjacent A.frigida was the highest in CK treatment,the content of available phosphorus adjacent C.microphylla was the highest in HG treatment,and the content of organic carbon and available phosphorus adjacent other shrubs was the highest in LG treatment.The relationship between the quantitative characteristics of shrub population and soil nutrients was as follows:soil organic carbon was positively correlated with the height,coverage and aboveground biomass of A.frigida and C.latens,and soil available phosphorus was significantly negatively correlated with the height and aboveground biomass of K.scoparia.Therefore,the stocking rate can affect the quantitative characteristic value of shrub plant population and its adjacent soil nutrient content.