羊草草原分解者亚系统的特性及作用

CHARACTERISTICS AND FUNCTION OF DECOMPOSER SUBSYSTEM IN LEYMUS CHINESIS STEPPE

在内蒙古羊草（Ｌｅｙｍｕｓｃｈｉｎｅｎｓｉｓ）草原，对其分解者亚系统的特性及作用开展研究，采用网袋法对不同物候期羊草植株和凋落物的分解作用进行了测定。结果如下：１．植株分解的最初２－３ａ中，其残体表面的微生物生物量及转化酶、蛋白酶的活性均呈现返青期植株＞结实期植株＞果后营养期植株＞凋落物。植株分解的速度亦为上述规律。２．羊草植株被分解后，可提高临近土壤的微生物活性。各植株分解均引起土壤的Ｃ／Ｎ值下降，老熟植株分解使土壤的ＨＡ／ＦＡ值升高。３．幼嫩植株分解时，其体内营养元素会较快释放；凋落物分解则导致氮和磷元素的积累，但钾不会。４．通过指数衰减模型估算，羊草凋落物的分解常数为０．１５３ｇ／ｇ·ａ，９５％被分解掉约需１９ａ时间。５．羊草草原凋落物的最大积累量为年输入量的６．５４倍，即１１７５．６ｇ／ｍ￣２。６．分用凋落物的微生物其生物量平均为４．４×１０￣（－３）ｇ／ｇ·ＤＷ，微生物所含能量仅占凋落物贮存能量的０．５％左右。

he present paper studied the charactristics and functions of decomposer subsystem ofLeymus chinensis steppe in Inner Mongolia. The decompositions of litter of Leymus chinensis plant and materials in different phenological periods were determined by net-bag method. Themain results were as follows:1. The biomass of microorganisms and the activities of enzymes (protease and invertase)on the surface of the residues of young plants were higher than thatof old plants. The decomposing rate of young plants materials was faster than that of oldplants. 2.The activities of microorganisms in soil increased after the plant materials were re-turned to the soil.The ratio of C/N in soil decreased because the ratio of HA/FA was in-creased owing to the old plant material decomposition. 3. Fast release of nutrient elementsfrom young plant caused N and P to accumulate in litter; while K was released quickly in allplant materials.4. Based on the exponential model,the remain weight of organic C,the litterdecomposing rate was 0. 153g/g·a. It means that 95%of the decomposed litter would belasted for 19 year.5. the maximum accumulative quantity in the steppe was about 6. 54 timesof annual input quantity of the litter,reaching 1175. 6g/m￣2.6. The mean microbial biomass atthe surface of litter residues was about 4.4 ×10￣(-3)g/g· DW, the storage energy of the mi-croorganisms on the litter residues was only 0.5%of that of the litter.