Study On Vegetation And Soil Characteristics Of Grasses+ White Clover Grasslands Under Long-term Mowing And Grazing Utilization

Grass（Dactylis glomerata+Perennial ryegrass）+ white clover（Trifolium repens）grassland is one of the main grazing grasslands in karst mountainous areas of Yunnan-Guizhou Plateau.It plays an important role in the grassland husbandry production in this area,and is often degraded due to improper utilization.Therefore,it is a key to this kind of grassland for us to make some reasonable mowing and grazing pattern.In this study,the characteristics and changes of vegetation and soil under long-term two utilization patterns（rotation grazing grassland and mowing grassland）and three utilization patterns（rotational grazing grassland,rotational grazing+continuous grazing grassland and continuous grazing grassland）and natural grassland（control）in Xundian sheep breeding pasture of Yunnan province and Weining Zhuopu pasture of Guizhou Province were quantitatively studied,respectively.The aim of this study was clear the sensitive index of soil and herbage to grassland utilization patterns,and to explore the suitable grassland utilization pattern,and which will provides some scientific basis for the sustainable utilization of grass+white clover grasslands.The main results are as follows:For Xundian sheep breeding pasture,the biomass proportion of sown grasses and Trifolium repens were 50.7% to 56.1% and 9.3% to 11.1% in rotation grazing grassland,and 38.2% to 43.1% and 4.4% to 7.6% in mowing grassland,respectively.The plant species richness of rotation grazing grassland < mowing grassland and natural grassland,while the plant species Shannon-wiener and Pielou evenness indices were rotaton grazing grassland and mowing grassland >natural grassland.The density of Eragrostis nigra and Dactylis glomerata in rotation grazing grassland were higher and even distributed in space than the others,and whist they were lower density and small individual plant in mowing grassland and natural grassland.The relationship estbetween plant species diversity indices and herbage nutritional value varied with different kinds of nutrient content and plant functional group,and Trifolium repens and grasses with a higher biomass composition were beneficial for maintaining higher herbage nutritional value.The rotational grazing grassland and mowing grassland had a high herbage quality and soil nutrients（total nitrogen and organic matter）,and rotation grazing grassland was better than mowing grassland.The herbage nutrient was more sensitive to management pattern than the soil.For Weining Zhuopu pasture,the biomass composition of sown herbage in rotation grazing grassland was highest（about 80%）than other mixed grasslands（<50%）,and their Trifolium repens biomass composition was generally less than 10%.The biomass proportion and stolon weight of Trifolium repens was rotational grazing+continuous grazing grassland was highest than the others,while the individual weight of Trifolium repens stolon was continuous grazing grassland >rotation grazing grassland.The plant Patrick,Shannon-Wiener,Simpson and Pielou diversity indices in rotation grazing grassland were lowest than the others.The rotational grazing grassland had a good herbage quality and soil nutrient,while they were low in the natural grassland.The herbage nutrient value in rotation grazing grassland was higher than the others,and the soil was severe acidification in rotation grazing grassland,rotation grazing +contionuus grazing grassland and natural grassland.Compared with the rotational grazing grassland,after many years of grazing and mowing utilization,the mowing grassland,rotation grazing +continuious grazing grassland and continuious grazing grassland had an unreasonable swards structure,low herbage productivity and obvious degradation trend.The sensitive indices to grassland utilization patterns are forage nutrients and soil organic matter and total N,and rotational grazing is a suitable grassland utilization mode in the study area.In the practice of grassland management,we advise timely adjust the mowing and grazing pattern,and apply more organic fertilizer,which will be benefit for productivity maintenance and sustainable utilization of grass（Dactylis glomerata+Perennial ryegrass）+ white clover（Trifolium repens）grasslands.