磷肥对环青海湖高寒草原植物群落特征的影响

Effects of phosphatic fertilizer addition on plant community characteristics in an alpine grassland around Qinghai Lake

为探讨环青海湖地区高寒草原适宜的磷肥施用量,2017年在海晏县西海镇轻度退化高寒草原上,选用磷酸二铵,设置0(CK)、120(P_1)、240(P_2)、360(P_3)、480 kg·hm^(–2)(P_4) 5个施肥梯度,以草原植物群落特征变化为指标,筛选区域磷肥增施的优化方案。结果表明,增施磷酸二铵后草原植物群落中禾本科、莎草科和豆科植物的重要值显著增加(P <0.05),其中青藏扁蓿豆(Melilotoides archiducis-nicolai)的盖度和重要值极显著增加(P <0.01)。不同施肥梯度下草原群落生物量显著增加(P <0.05),磷酸二铵施用量为120～240 kg·hm^(–2)时草地群落生物量较高,比对照提高31.28%～47.13%,净收益比对照增加28.42%～38.37%。适宜环青海湖高寒草原经济可行的磷酸二铵施用量为120～240 kg·hm^(–2)。

To determine the suitable amount of phosphate fertilizer to be used in an alpine grassland in the area surrounding Qinghai Lake,experiments were conducted in the mildly degraded alpine grassland of Xihai Town,Haiyan County in 2017.Treatments included 0(CK),120(P1),240(P2),360(P3),and 480 kg·ha^–1(P4).The goal of the research was to examine the change in grassland plant community characteristics,to determine the optimal scheme for regional fertilization.The results showed that the application of diammonium phosphate significantly increased the important values for grasses,sedges,and legumes in grassland communities(P<0.05).In particular,the coverage and importance value of lentils(Melilotoides archiducis-nicolai)(P<0.01).The biomass of the grassland community increased significantly under different fertilization gradients(P<0.05).The biomass of grassland community was higher,which was 31.28% ~47.13% higher than that of the control,When the application rate of diammonium phosphate was 120~240 kg·ha^–1.The net income increased by 28.42% ~38.37% compared with the control.The economically feasible amount of DAP was 120~240 kg·ha^–1 in the alpine grassland around Qinghai Lake.