火烧后草原植物营养和热值的变化

Response of nutrient and caloric value in grassland plant following burning

研究了不同时间不同频次的草原火烧后，植物体内营养含量和热值的变化．结果表明，割草地火烧后当年羊草体内营养含量普遍高于割草未饶地，但随着生长季的推进，火烧地羊革体内N、Ca、C的含量逐渐低于未挠地．大针茅也表现出与羊草相似的变化规律，只是在生长季后期，末浇地大针茅体内粗纤维含量高于火烧地．火烧后翌年，火烧地羊草体内除粗纤维外，其它营养含量仍高于未饶地．对于二次火烧样地（春浇地和秋烧地），羊草体内营养含量普遍下降．火烧增加了羊草体内大多数营养元素（Zn、Mn、K、Ca、Mg）的含量，降低了Na、P的含量，而Fe、Cu、Al的含量没有一定的变化规律．火烧后当年，羊草体内热值含量降低，大针茅体内热值含量增加，群落混合样品热值增加．总体来看，火烧可以作为一种工具，合理使用能够提高草原植物体内的营养含量和热值水平．

Changes in plant nutrient content and caloric value following grassland burning in various time and frequencies were studied. In the same year of burning in field mown and burned, the nutrient content in Aneurolepidium chinese generally grew higher than that of unburned field. But with the proceeding of growth season, the contents of N, Ca and C in Aneurolepidium chinese in burned field went gradually down lower that that of unburned field. The changing pattern of nutrient content in Stipa grandis was nearly similar to Aneurolepidium chinese, only in late stage of growth period the content of coarse fiber in Stipa grandis of unburned field exceeded that of burned field. In the second year following burning, the nutrient content in Aneurolepidium chinese of burned field was still higher than that of unburned field, except for coarse fiber. In field burned in spring and autumn. The nutrient content in Aneurolepidium chinese generally went down. As for the elements in Aneurolepidium Chinese, burning increased the contents of Zn, Mn, K, Ca and Mg, decreased the contents of Na and P, exerted an irregular influence on the contents of Fe, Cu and Al. In the same year of burning, the caloric value of Aneurolepidium chinese decreased,that of Stipa grandis increased, that of community mixture increased. Generally speaking,proper burning could be adopted to be a tool to increase the nutrient content and caloric value of grassland plants.