移除和沙埋对沙土生物结皮土壤蒸发的影响

利用长期定位试验,对不同施肥条件的苜蓿草地植被特征变化进行了研究。结果表明,不同施肥处理下连作苜蓿草地群落物种丰富度指数变化不显著。群落盖度增大,群落高度亦明显增加。施肥可维持群落多样性和稳定性,提高苜蓿草地生产力。施肥后苜蓿种群生态位宽度明显上升,竞争力相对增强,而杂类草生态位宽度降低,竞争力相对减弱。连作施肥条件下苜蓿种群与其它物种之间没有最大的生态位重叠,杂类草之间生态位重叠较大,它们之间的竞争较为激烈且占主要地位,施肥可提高苜蓿草地质量和经济价值。狗尾草等杂草入侵是导致苜蓿人工草地退化的一个重要影响因素。

Effects of Biological Crust Removal and Sand Mulching on Soil Evaporation in a Sandy Soil

The changes of the vegetation characteristics of alfalfa grasslands under different fertilization schemes were analyzed with the trial of plot experiments.The results indicate that the species richness index of the continuous cropping alfalfa grassland did not significantly change under different fertilizer treatments,along with considerably increased community coverage,and significantly raised community heights.Fertilization could maintain species diversity and community stability and enhance alfalfa grass...