马尾松林向香樟林改造林下植物功能多样性研究

在生物多样性研究中,功能多样性比物种多样性可以更直接地反映生态系统的结构和功能,从而在群落生态学研究中受到越来越多的推崇。马尾松次生纯林是一种亟待改造的森林类型,而在亚热带地区香樟是马尾松林改造的理想树种之一。为了完善马尾松林向香樟林改造的研究,以更好地指导马尾松林改造的实践,本文用空间代替时间的方法,选取马尾松林向香樟林改造过程中4种不同阶段群落为研究对象,对林下灌木层和草本层植物的功能性状及其多样性展开了研究。结果表明:(1)随着森林改造的进行,林下植物的物种数目、功能性状多样性均表现为先上升后下降的变化趋势,其中功能丰富度和功能均匀度在改造前期达到峰值,而物种数目和功能离散度则在改造中期表现最高。(2)比较森林改造的4个时期,林下植物功能多样性的综合表现大致为:改造前期改造中期改造后期未改造时期。(3)森林改造过程中,林下植物"光响应性状"和"繁殖性状"的功能多样性变化趋势相似,但前者比后者对改造的响应更敏感。(4)在森林改造过程中,林下植物的生长、发育和扩散受到林下光照资源的影响,并在长时间的生物竞争中逐渐表现为物种种类、多度和空间分布格局的变化,最终影响生态系统功能。(5)马尾松林向香樟林的改造加速了群落的演替进程,提升了群落的功能,但仍存在林下植物功能多样性下降等问题。在对马尾松次生纯林改造过程中,应选择合适的造林密度和混交林的改造模式。

The functional diversity of understory plants during the transformation from Pinus massoniana to Cinnamomum camphora forest

In the study of biological diversity, functional diversity can reflect the structure and function of the ecosystem better than species diversity. Therefore, more and more scholars advocate replacing species diversity with functional diversity in the study of community ecology. At present, the secondary pure Pinus massoniana forest is a type of forest that urgently needs to be transformed, and Cinnamomum camphora is one of the ideal tree species for P. massoniana forest transformation in sub-tropical regions. In order to improve the study on the transformation of P. massoniana forest to C. camphora forest and guide the transformation of P. massoniana forest in practice, four communities at different stages of the transformation of P. massoniana forest to C. camphora forest were selected to study the functional characters and diversity of the understory shrub layer and herb layer. The results showed that: (1) With the progress of forest transformation, the number of species and the diversity of functional traits of understory plants indicated a trend of increasing first and then decreasing, among which the functional richness and functional evenness peaked at the early stage of the transformation, while the number of species and functional divergence peaked at the middle stage of the transformation. (2) Compared with the four stages of forest transformation, the comprehensive performance of the functional diversity of understory plants was ranked as follows: early stage of transformed community > middle stage of transformed community > late stage of transformed community > untransformed community. (3) In the process of transformation, the variation trend of functional traits and diversity of "light response traits" and "reproductive traits" of understory plants was similar, but the former was more sensitive to the forest transformation than the latter. (4) In the process of forest transformation, the growth, development and diffusion of understory plants were affected by undergrowth light resources. With the species competition, the growth, development and diffusion of undergrowth plants were gradually manifested as the change of species diversity and spatial distribution pattern, which ultimately affected the function of the ecosystem. (5) The transformation from P. massoniana to C. camphora forest accelerated the succession process of the community and improved the function of the community. However, there were still problems such as uneven distribution of resources and decrease of functional diversity of plants due to the serious interference of trees on the light resources of understory in the late stage of the transformation. In the reconstruction of secondary pure forest of P. massoniana, suitable reforestation density and the model of mixed forest should be selected.