内蒙古羊草草原群落主要植物的热值动态

Dynamics of caloric values of major plant species in Leymus chinensis steppe of Inner Mongolia

对内蒙古羊草草原主要植物种群的干重热值动态研究表明 ,热值随植物种类、植物部位、取样时植物所处物候期及气候条件的不同而变化 ,羊草草原主要植物种群地上部分热值的变动范围在 1 570 3～1 81 4 1 J/ g之间 ,其中灌木小叶锦鸡儿 (Caragana microphylla)的热值最高 ,禾草类植物的热值多数较高 ,而大多数杂类草的热值相对较低 ;主要植物种群地下部分热值的分布范围为 1 50 51～ 1 641 0 J/ g。其中根茎型草地下部分热值较高。不同种类植物地下部分热值差异并不与地上部分一致。根茎型禾草地上、地下部分热值差异较小 ,而须根型植物差异较大。不同种群的植物地上部分热值随植物物候期的不同而波动 ,其变化规律是与植物种群本身的生物学特性相联系的。不同植物种群热值的年际波动规律有所不同 ,羊草(Leymus chinensis)、大针茅 (Stipa grandis)和洽草 (Koeloria cristata)的年际热值波动相关显著 ,但与生长季降水量和生长季累积日照时数之间无明显相关性。在某种程度上 ,植物热值的种内变化反映了植物生长状况的差异。

Leymus chinensis steppe is a distinctive formation in the east of Eurasia st eppe region, and has an extensive distribution in the steppe region of China. It is the important mowing and grazing rangeland in Inner Mongolia and has high ut ilizable value. This paper deals with the dynamics of caloric values of major pl ant species in the steppe. The sample site was located at Leymus chinensis s teppe community in Xilin Gol league of Inner Mongolia (43°38′N, 116°43′E), T he caloric value was measured by GR3500 type oxygen bomb calorimeter. The result s showed: the caloric values varied with plant species, parts of plant, sampling seasons and climatic conditions. The caloric values of aboveground parts for ma jor plant populations varied from 15703 to 18141 J/g. The shrub population (Ca ragana microphylla) had the highest value. The caloric values of most of grass es are higher than that of most of forbs. The caloric values of underground part s for major populations varied from 15051～16410J/g. Among them, the values of u nderground parts of rhizome grasses were relatively high. The difference of unde rground caloric values between species wasn't similar with that of aboveground. There was less difference between aboveground and underground part of rhizome gr asses than that of grasses with fibrous roots. The caloric values of aboveground parts of all species varied with phonological phase, and the change was related to biological characteristics of species. The annual fluctuation of the caloric values was different between species except that there was significant correlat ion between Leymus chinensis, Stipa grandis and Koeloria cristata. There were not significant correlations between caloric value and precipitation and s unshine hours in growing season. To some extent, the variation of caloric values within a species reflected on difference of the developmental status.as