高寒草甸土壤水和营养对草地生产的影响

SOIL MOISTURE AND NUTRIENT AFFECT GRASSLAND PRODUCTION IN ALPINE MEADOW

高寒草甸莎草科草地的土壤水分和营养决定着草地质量及其生产能力。0～50厘米土层的贮水量为155～178毫米时,莎草科草地演替成莎草科一禾本科草地,这类草地青草供给期长,产草量高和营养物质含量丰富,并能合理利用土壤水,使土壤氮保持自然平衡,为理想的刈牧兼用草地。当土壤贮水量为182～217毫米时,演替为禾本科草地,其产草量与莎草科一禾本科草地相近,粗蛋白质生产量降低,特别是牧草拔节一开花期急剧下降,到种子成熟期得到恢复。这类草地产草量集中,适于割草利用。土壤贮水量低于150毫米时,草地植被以莎草科牧草为主,其产草量低,能用作放牧地。

The quality and productivity of sedge pasture in the alpine meadow area are determined by the moisture ana nutrient of the soil. Results from this experiment showed that when the soil moisture was between 155 to 178 mm on the soil surface from o to 50 cm depth,the sedge pasture in succession to sedge-grass pasture which had a long growth period,higher yield and nutrient content. Because of the reasonable use of the soil moisture and the maintenance of the natural balance of soil nitrogen, this type of pasture was was suitable for cutting and grazing. When the soil moisture was maintained between 182 to 217mm, pasture was dominated by grass which had a similar yield to sedge-grass dominated one. But the protein yield of this pasture was lower particularly at the growth stage from jointing stage to florescence because of the great utilization of soilnitrogen by pasture at this stage. The protein yield recovered at seed mature stage. This type of pasture had a peak yield and was suitable for cutting. When the soil moiture content was below 150mm,because pasture dominated by sedge which yielded lower and was only suitable for grazing.