区系次生度和生态次生度在生物多样性评价中的应用研究

在分析Patrick、Simpson、Shannon-Wiener及Pielou均匀度等生物多样性评价指数的基础上,提出了区系次生度(F)和生态次生度(E)等指标,定义区系次生度(F)是生态系统中已进入的外来种及已丧失的原生种的种类的百分比,它只与这些物种的种类变化有关而与它们的植株数量变化无关,即F={[a/(b1+a)+b2/(b1+b2)]÷2}×100%;定义生态次生度(E)由系统中外来种的重要值与系统中现存每个种的重要值之和的比值,以及由系统中已经丧失的原生种的重要值与系统中曾经拥有的原生种的重要值之和的比值构成,即E={[i∑=s 1 Ai/(i∑m=1 B1i+i∑=s 1 Ai)+i∑=n 1 B2i/(i∑m=1 B1i+i∑=n 1 B2i)]÷2}×100%。通过在滇西北研究的实例分析,说明引入区系次生度和生态次生度等新指数的合理性和必要性。采用系统中外来入侵种的种类和数量及原生种的种类和数量的变化,用较为直观和易于获得的指标评价系统的生物多样性质量,为生物多样性评价、保护和管理提供更多的依据。

Conception and Application of Floristic Secondary Index and Ecological Secondary Index in Biodiversity Evaluation

Through reviewing a series of indexes used for evaluating biodiversity such as Patrick,Simpson,Shannon-Wiener and Pielou,it was analyzed that those indexes shared the common weakness of did not differentiate the emergence of the invasive species and also the disappearances of the native species in an ecosystem.In this paper,the authors proposed two concepts,namely floristic secondary index(F) and ecological secondary index(E) with the objective of establishing more reasonable and scientific evaluation on biodiversity of forest ecosystem.Here,floristic secondary index(F) is defined as a percentage about the existent amount of invasive species and the lost amount of native species in an ecosystem.It considers only species number of the invasive ones emerging and the local ones being lost,does not calculate the individual dominance of these exotic species and bereft species,F=a/(b1+a)+b2/(b1+b2)÷2×100%.Analogously,ecological secondary index(E) is defined as a ratio between the important value of the invasive species and the summation of important value for all species in an ecosystem,plus a ratio between important value of the native species disappeared and that of all native species including that of existent and disappeared,namely,E=∑s i=1 Ai/(∑m i=1 B1i+∑s i=1 Ai)+∑n i=1 B2i/(∑m i=1 B1i+∑n i=1 B2i)÷2×100%.Through sufficiently considering the change of invasive species and native species,finding direct and easy indexes for evaluation of biodiversity quality of ecosystem,more basis can be developed for evaluation,conservation and management of biodiversity.These two concepts have been used on biodiversity evaluation case of northwest Yunnan,the introduction of floristic secondary index and ecological secondary index have been proved to be reasonable and necessary.