北方半干旱区河流湿地优势植物的热值

Calorific values of dominant plant species on fluvial wetlands of semiarid northern China

热值反映植物对太阳能的利用效率,是能量与生物量之间转换的重要参数,是能流分析必不可少的基础资料;同时热值也是解释种群的适应性问题的重要依据。本文采集了锡林河湿地的8种主要植物,并用氧弹式热量仪测量其热值,阐述了这些植物的热值的动态变化规律,并对热值变化的原因作了探讨。结果表明:各物种的热值动态变化规律并不是统一的,这种变化可能与植物各器官热值的变化及生殖期出现的时间有关;各植物器官的热值普遍表现出穗的热值大于茎和叶;水生植物的热值明显小于中生性和湿中生性植物;种内热值变化随物候期变化有一定的规律,大约会出现2次低值、2次高值;种间热值差异是由于植物本身性质决定的,在相同生境和气候条件下,植物体中含能物质越多,就越易积聚热值,从而更适宜生长在此环境。

Calorific value reflects the utilization efficiency of solar energy by plants, and also, is an important parameter about the conversion of solar energy into biomass and for energy flow analysis. In the meanwhile, it is an important basis in explaining the adaptability of plant populations. The change patterns of the calorific values of eight dominant plant species on Xilin River fluvial wetlands were studied by oxygen bomb calorimeter, with the causes of the change patterns analyzed. The results showed that the calorific values of the test plant species had no unified change pattern, which was possibly related to the partitioning ratio of Calorific value in different plant organs and the timing when the reproductive period appeared. In general, spike had a higher calorific value than leaf and stem, and aquatic plants had obviously lower calorific value than mesophytes and wet mesophytes. Within a species, the change pattern of calorific value had certain relations to the phenophase, with approximately two lowest values and two highest values. Among the species, the differences in the calorific value were decided by the nature of the species themselves. Under the same habitat and climatic conditions, the species that contained more materials rich in energy could more easily accumulate calorific, and thus, more adaptable to grow under this environment.