火因子对荒漠化草原草本层片植物群落组成的影响

火烧是世界许多地区关键的生态因子,也是人工和自然生态系统重要的干扰因素和管理工具,对格局与过程有着深刻的影响。采用人为放火试验研究了春季不同时间火烧对典型温带荒漠化草原草本植物群落组成的影响,结果表明:晚春火烧后当年,草本植物层片物种多度显著高于未火烧样地(P<0.05),而晚春火烧后第2年和早春火烧当年草本植物层片物种多度与未火烧样地差异不显著(P>0.05);晚春火烧后当年和第2年及早春火烧后当年,草本植物物种丰富度、多样性和均匀度均有所降低,且晚春火烧对植物群落组成的影响大于早春火烧。晚春火烧当年草本植物层片地上部分生物量显著大于未火烧样地(P<0.05),而晚春火烧后第2年和早春火烧当年草本植物层片地上部分生物量大于未火烧样地,但差异不显著(P>0.05);不同物种多度、高生长对火因子的响应不同。表明春季不同时间火烧处理对荒漠化草原草本植物层片植物群落组成的影响存在差异。

Effects of fire on the structure of herbage synusia vegetation in desertified steppe, North China

Fire is a powerful and rapidly acting modifier of the environment, which is of global importance in natural and man-managed ecosystems both as a destructive force and management tool. It plays an important role in moulding the key plant features, population dynamics, community structures and plant species diversity, and contributing to the evolution and maintenance of plant communities. The aim of this paper it to understand the effects of fire on the vegetation structure of herbage synusia in desertified steppe and to offer a solid basis for scientific and sustainable management of desertified lands.We take the herbaceous vegetation in desertified steppe occurring in the southeast fringe of temperate Tengger desert, north China as a case study and collected the related data through field survey after artificial fire in the spring. The species, individual number, height were investigated monthly, using these data, we analyzed the plant species diversity, the abundance and the aboveground biomass, and elucidate the influence of different spring fire regimes on herbage vegetation composition by introducing some indices, such as the abundance index, the Simpson index, the Shannon-Wiener index and the Pielou index.Results from this study showed that: in the first year after both late and early spring fire treatment, the species abundance and the aboveground biomass of the herbage vegetation in burned plots was greater than that of unburned plots (control), but no significant differences were found between the early spring fire treatment and the control. In comparison with the unburned plots, the species abundance increased by 26% and 5.8% and the aboveground biomass increased by 76.7% and 17.5% in late and early spring fire treatments, respectively. In the second year after late spring fire treatment, the species abundance and the aboveground biomass in burned plots decreased by 10.8% and 20.5%, respectively, in comparison with the unburned plots, and no significant differences were found between them. The species richness, diversity and evenness of herbage vegetation in the first year of both early and late spring burning treatment and in the second year of late spring burning treatment decreased in comparison with the unburned plots, and the effects of fire treatment in late spring on herbaceous vegetation composition were greater than those in the early. The response of the abundance and height of different plant species varied. The understanding of the influences of fire on herbaceous vegetation structure in this study indicated that the responses of herbage synusia vegetation in the desertified steppe to fire treatments at different times are far different, which implies timing of fire treatment and the careful management of desertified ecosystem by using fire as a tool.