【作者】 王静；

【导师】 宝音陶格涛；

【作者基本信息】 内蒙古大学 ， 生态学， 2005， 硕士

【摘要】 本文以典型草原及其退化群落为研究对象,在2002年到2004年期间对锡林河中游典型草原群落的组成与蒸散及其季节动态进行了测定,并对典型草原的生态用水进行了初步的研究,研究结果如下: 典型草原的主要利用方式为放牧利用,在不同的放牧压力下草原群落发生了不同程度的退化,包括植被的退化和土壤的退化。羊草草原群落的密度和物种多样性在中度退化群落中最高;群落的生物量随着退化逐渐降低。大针茅草原随着退化密度,生物量和物种多样性都呈下降趋势。群落中多年生根茎禾草对放牧的适应能力较多年生丛生禾草差,丛生禾草在退化群落中取代了根茎禾草的优势地位。同时,旱生植物的比重随退化不断增加,群落逐渐向旱生方向发展。随着群落的退化,群落中主要物种叶面积系数K逐渐增大,叶面积指数下降,各物种对叶片生长投入的比例随退化加大。土壤容重也随着群落的退化发生了一定的改变。羊草草原表层土壤容重随退化显著降低。大针茅草原两个群落之间土壤容重的差异不显著。 群落的土壤含水量随着退化呈现下降趋势。各群落对土壤水分的利用主要集中在表层20或30cm,并且表层土壤的含水量对降水的响应迅速,因此表层土壤的含水量的波动大于深层土壤。群落的土壤贮水量受到土壤性质和群落蒸散耗水的强烈影响,但从整个生长季的土壤平均贮水量,在羊草草原随着群落的退化逐渐降低,在大针茅草原变化较小。 群落的日蒸散受到多个因子的综合影响。植被较好的群落其日蒸散与土壤含水量变化趋势相符,在6月底达到最高;在羊草重度退化群落和大针茅退化群落,日蒸散主要与气温呈正相关,高峰出现在7月底。无论是平水年还是欠水年,各个群落各月累积蒸散量均与平均气温的变化趋势相符。6-7月份群落蒸散耗水量基本与降水量相当,而在随后的7-8月份,蒸散量远低于降水量,这个时期是群落水分积累的时期。 羊草草原群落在生长季内总的蒸散量随着退化程度的增加逐渐的降低,大针茅草原两个群落的总蒸散量相差不多。各群落总蒸散量都未超出同期的降水量,所以无论是在丰水年还是在欠水年,群落蒸散所消耗的水分都可以完全通过天然降水得到补给。随着退化,群落对更多还原

【Abstract】 The paper studied on characteristics of composition and evapotranspiration of the typical steppe and its dynamic changes of the seasons in the middle reaches of Xilin River Basin from 2002 to 2004. And the ecological use of water of the typical steppe was preliminary researched. The results are as follows:The main way of utility of the typical steppe is grazing. The steppes deteriorated to different degrees, including the deterioration of both plants and the soil. The biomass of Leymus chinensis steppe reduced with the deterioration. The density and the diversity index of the species were highest in mid-deteriorated communities of Leymus chinensis steppe. The biomass, density and diversity index of species all decreased with the deterioration in Stipa grandis steppe. The adaptability of grazing stress of the perennial rhizome grasses was weaker than that of the perennial brunch grasses. Dominance of the perennial rhizome grasses was replaced by the perennial brunch grasses. Furthermore, amount of xerophytes rised gradually. With the deterioration, the communities developed to xerophilization. The leaf area coefficient-K increased gradually with deterioration. The investment on leaf growth of each species in deteriorated communities was higher than that in original communities. And the leaf area index reduced with the deterioration. Moreover, with the deterioration, the soil bulk density reduced in Leymus chinensis steppe and changed a little in Stipa grandis steppe.With the deterioration, the soil water content (SWC) decreased. The surface layer of 20 or 30cm was the main layer used by communities. The SWC in this layer responded to the precipitation quickly. So the SWC in the surface layer fluctuated more dramatically than that in the deep layer. The soil bulk density (SBD) and the community evapotranspiration affected storage water of the soil dramatically. With the deterioration, the average SBD ofgrowing period reduced in Leymus chinensis steppe and changed little in Stipa grandis steppe.Daily community evapotranspiration (ET) was synthetically affected by several factors. Daily ET of the better communities correlated positively with SWC and reached the peak value in the end of June. And daily ET of the heavy deteriorated communities correlated positively with average air temperature and reached the top in the end of July. Monthly ET of each community varied with average air temperature both in equal water years and in low water years. Community ET was equal to the precipitation approximately in the end of June and the beginning of July. And it was far lower than the precipitation in the end of July and the beginning of August. The soil water of the communities accumulated in this period.Sum ET of the growing period of Leymus chinensis steppe reduced with the deterioration and changed little in Stipa grandis steppe. Sum ET of each community was not beyond precipitation both in the equal water years and in the low water years. And the water of the soil consumed by community ET could be replenished completely by the precipitation in the same term. Water use efficient of the deteriorated communities was lower than the original communities. The ratio of sum ET in ecological use of water became lower in deteriorated communities. These showed that development of the communities trended to xerophilization.Ecological use of water consumption decreased with the deterioration in Leymus chinensis steppe and was equal in the two communities of Stipa grandis steppe approximately. Sum ecological use of water consumption of this area was lower than sum precipitation of the same period in the equal water years and higher in the low water years.更多还原