锡林河流域合理割草制度的研究

The Study of Rational Cutting System on the Grassland of Xilin River Basin.

连续１６年在锡林河流域进行的研究结果如下：该地区的最适割草时期为８月中旬，合理轮割为割一年休一年或割二年休一年，利用率控制在５０％左右，留茬高度为１２ｃｍ左右。割草使群落地上生物量和密度下降，优良牧草在群落中的比例减少，杂类草增加，并引起生境条件恶化。不同的割草制度有共同的演替趋势，但所处的演替阶段不同，１６年连续刈割已使羊草占优势的草原演替为艹洽草占优势的草原。从割草制度与割草地改良看，施Ｎ肥、定量补施各种亏损营养元素、深耙松土和喷施硝酸稀土均取得良好的效果。留茬高度与损耗率之间有一定的相关关系，多数较高大的植物符合＾ｙ＝ａ＋ｂｘ方程；少数丛生或低矮的植物符合＾ｙ＝ａ＋ｂｌｎｘ方程；另外，合理轮割对植物营养元素的贮量与分配，对土壤种子库中种子数量的增加均有利。

The results of study on the grassland of Xilin river basin for 16 years were as follows. The best mowing time is middle of August. Rational mowing regime is mowing every second year or mowing for two years and stopped for the following year. Utilization rate is controlled at about 50%. Stubble height is about 12cm. Mowing reduces the above ground biomass and density of community, reduces fine grass percentage in the community, increases forbs and leads habitat worsen. Different mowing systems have the same succession tendency, but stay in different succession stages, Dominant plant of Leymus chinensis was replaced by Koeleria cristata after 16 years successive mowing. Application of nitrogen, quantitative application of all kinds of absent nutrition elements, loosening the soil by harrow and spraying nitric acid rare earth have good effects for grassland improvement. Stubble height and loss proportion have certainly corresponding relationship. Major high plants accord with =a+bx equation. Minor rosette or low plants accord with =a+blnx equation. Rational rotation mowing is beneficial for storage and distribution of plant nutrition elements and increasing seed number of soil seed bank.\=