青藏高原围封刈割草地植物群落及土壤养分对施肥的响应

Responding of plant community and soilnutrient in fenced mowing Qinghai-Tibetan meadow to fertilization

施肥作为改良草地的措施之一,近年来开始在天然草地被广泛应用.本研究通过对青藏高原围封刈割天然草地添加氮、磷、钾肥及氮磷复合肥,研究了不同施肥处理对高寒草地群落结构以及土壤速效养分的影响.结果表明,施肥当年草地群落高度、密度和地上生物量不同程度增加,地上生物量禾本科分配增加,毒草分配降低,施肥改良了草地生长状况.施肥次年禾本科草类所占草地总生物量比例降低,毒草和杂类草所占比例增加,高寒围封刈割草地在冬季不适宜进行常规放牧.15.3 g/m2钾肥、7.5 g/m2复合肥和3.0 g/m2氮肥梯度为该地区围封刈割草地最佳的施肥水平.磷并不是该地区高寒围封刈割草地的养分限制性因子;施钾肥有效的增加了草地生物量及表层土壤速效钾含量,对草地植物群落结构有重要的影响.

As an efficient method to improve grassland, fertilization is widely used in natural grassland in recent years. This re- search applied fertilizer to fenced alpine meadow in Qinghai-Tibetan plateau to study the response of plant community structure and soil nutrient. The results showed that in the first year of fertilization ,the plant community average height, density and above ground biomass increased in different degrees. Grass biomass increased but biomass of poisonous weeds decreased. Fertilization improved grassland condition. In the second year after fertilization, grass biomass percentage decreased, while percentage of poi- sonous and weed biomass increased. Fenced alpine meadow was not accustomed to grazing in winter. 3.0 g/m^2 nitrogen,7. 5 g/ m^2 compound fertilizer and 15.3 g/m^2 potassium was the optimized fertilization combination in this area. Phosphorus was not the limiting nutrient for this grassland. Potassium could improve above ground biomass and available potassium in surface layer soil, and had great influence on plant community structure.