长期施肥对黄土高原典型草原群落稳定性的影响及机制研究

施肥是当前草地生态系统最常见的人为干扰方式之一,可导致草地生物多样性和生态系统稳定性发生显著变化.该研究以黄土高原典型草原为研究对象,通过连续8年的氮肥(尿素)野外添加试验,分析不同氮肥处理(分别为0、5、10、20、40和80 g·m-2)对草地群落稳定性的影响,并分析检验可能影响群落稳定性的四个潜在机制(物种多样性...

Effect of Long term Fertilization on Community Stability of Typical Steppe and the Underlying Mechanisms on the Loess Plateau

Fertilization is one of the most common ways of human disturbance in the current grassland ecosystems,which can lead to changes in grassland biodiversity and ecosystem stability.At present,a few studies,however,have explored the effect of fertilization on community stability and the underlying mechanisms,but there are many controversies.For this reason,we took the typical steppe of the Loess Plateau as the research object,and through 8 consecutive years of field experiment of adding nitrogen fertilizer(urea),we studied different nitrogen fertilizer treatments(respectively 0,5,10,20,40,80 g·m^-2)influence on the stability of the grassland ecosystem,and tested four underlying mechanisms(species diversity,species synchrony,portfolio effect,dominance)that may affect the stability of community,to clarify the impact of fertilization on community stability and its underlying mechanism thus providing a theoretical basis for the rational use of grassland restoration on the Loess Plateau.The results showed that:(1)as the fertilization level increased,the community stability(S)decreased,and it began to decrease significantly when the fertilization treatment was 20 g·m^-2(P<0.01).(2)Fertilization significantly reduced the species richness(R)and dominance index(D)(P<0.01).However,the species synchrony(B)and the mean-variance ratio index(z)did not change significantly(P>0.05).(3)There was a positive correlation between species richness(R)and community stability(S),while dominance index(D)was not correlated with community stability(S).Studies suggested that under the disturbance of fertilization,the decline in species richness of typical steppe on the Loess Plateau led to a decline in community stability,indicating that species diversity plays an important role in maintaining the stability of grassland ecosystem.