不同水平的仙湖苏铁种群在土壤资源上的生态位宽度

Niche breadth of Cycas fairylakea genet and clone population on soil resource

在基株和无性系两个水平上,分析了珍稀濒危植物仙湖苏铁种群在土壤资源上的生态位宽度,以及该种群对土壤资源的潜在利用能力,探讨该种群对资源的利用状况,从而为种群的保护提供科学依据。结果表明,在有机质、全氮、速效磷、速效钾等土壤养分资源轴上,无性系种群的生态位宽度大于基株种群;而且,无性系种群比基株种群具有更大的潜在利用土壤资源的能力,说明无性繁殖可能是种群在日益恶化的生境中赖以生存的主要方式。当土壤有机质在3.348%～3.832%、全氮在0.164%～0.186%、速效磷在2.092～2.868mg/kg、速效钾含量在108.34～137.28mg/kg范围之间时,种群分布的个体数最多。因此,抑制周边生境恶化、改善土壤养分结构将有助于促进仙湖苏铁种群的恢复和发展。

A population of wild Cycas fairylakea was discovered in November of 1999 in Tanglang Mountain, Shenzhen City. The total number of individuals is less than 2000. Thus, it is an endangered species according to the new criteria of IUCN Red Categories. The population can reproduce itself by sexual and asexual style so that genet population and clone population have been produced respectively. In this paper, in terms of two levels-genet and clone population, the niche breadths and the potential utilization capability of C. fairylakea on soil resource were calculated and analyzed in order to guide the protection of the population. The results showed that the niche breadth of clone population was larger than that of genet population on soil resource composition, i.e., organic matter, total nitrogen, readily available phosphorus and potassium, and moreover, the potential utilization of clone population on soil resource was better than that of genet population. Since the clone population had more actual resource utilization and bigger potential utilization capability, the asexual reproduction perhaps will be the main survival style of the population if the habit has been damaged gradually. According to the results when there were 3.348%～3.832% organic matter, 0.164% ～ 0.186% total nitrogen, readily available phosphorus 2.092～2.868 mg/kg and readily available potassium 108.34 ～ 137.28 mg/kg in soil, the most individuals of C. fairylakea population appeared. Therefore perhaps these methods such as ameliorating the soil nutrition and forbidding the retrogression of forest will be helpful in recovering and developing the population.