桂西南喀斯特季节性雨林木本植物萌生更新的时空格局及其形成机制

The karst seasonal rain forest in the southwest Guangxi, form and developed on the carbonate bedrock in the climatic conditions of tropical northern margin, is the most unique type of karst forests in the world. It supports very high level of endemic plant species, vertebrates and invertebrates, and exerts important ecological functions such as preventing rocky desertification. Due to human interference and global change, the distribution range of this ecosystem has gradually reduced during recent years. Therefore the ecological restoration and reconstruction is a matter of great urgency. Most tree species in karst seasonal rain forests in the southern China are capable of sprouting because of the special eco-environment and community structure in this area, and such sprouting ability plays a crucial role in self-regeneration in a rigorous habitat of karst forests. It is of theoretical and practical significance to investigate the sprouting regenerate strategy of typical vegetation and understand forest regeneration and dynamic in this area. We need to enhance our understanding in how this widespread trait of sprouting regeneration was formed and adapted to environments, and how genetics characteristics of species and functional traits were corelated. We hypothesize that this trait is formed by functional selection in the evolution of species in this distinctive environmental characteristic of karst seasonal rain forest. Based on the two field census data of sprouting in 2011 and 2016 in a 15 ha seasonal rain forest dynamics plot in northern tropical karst in Nonggang, Guangxi, southern China, we will study the species composition, structure, spatial pattern, dynamic change of sprouting species and their formation mechanisms. The results of this study will provide theoretical and practical basis for revealing population regeneration and vegetation dynamics in the harsh terrestrial environment of tropical karst seasonal rain forest, and restoration and reconstruction in karst rocky desertification system.

桂西南喀斯特季节性雨林是全球最为独特的热带喀斯特森林，是在热带北缘气候条件下碳酸盐岩基质上发生发展的特殊类型，具备重要的生态功能。由于人为干扰和全球变化影响，该生态系统分布范围日趋缩小，开展生态恢复和重建迫在眉睫。萌生更新是喀斯特季节性雨林多数树种的重要特性，这对严酷环境条件下群落的自我更新有重要的作用。那么该森林群落中广布的萌生更新特性是如何形成的，是环境的长期适应、物种自身的遗传属性还是功能属性？亦或是多种因素的集合？我们认为这是由基于喀斯特独特的环境特征在物种进化过程中的功能选择形成的。本研究拟以弄岗喀斯特季节性雨林15ha样地为平台，以2011年和2016年两次样地调查中树木萌生数据为基础，对样地内萌生树种组成、结构、分布格局、动态特征及其形成机制等展开研究。研究结果将为喀斯特季节性雨林严酷环境中种群更新、植被动态等研究提供理论和方法，为周边石漠化生态系统恢复提供理论和实践依据。

桂西南喀斯特季节性雨林是全球最为独特的热带喀斯特森林，是在热带北缘气候条件下碳酸盐岩基质上发生发展的特殊类型，具备重要的生态功能。由于人为干扰和全球变化影响，该生态系统分布范围日趋缩小，开展生态恢复和重建迫在眉睫。萌生更新是喀斯特季节性雨林多数树种的重要特性，这对严酷环境条件下群落的自我更新有重要的作用。那么该森林群落中广布的萌生更新特性是如何形成的，是环境的长期适应、物种自身的遗传属性还是功能属性？亦或是多种因素的集合？我们认为这是由基于喀斯特独特的环境特征在物种进化过程中的功能选择形成的。本项目以弄岗喀斯特季节性雨林15公顷样地为平台，以2011年和2016年两次样地调查中树木萌生数据为基础，对样地内萌生树种组成、结构、分布格局、动态特征及其形成机制等展开研究。研究结果将为热带喀斯特季节性雨林严酷环境中种群更新、植被动态研究提供理论和方法以及为周边石漠化生态系统恢复提供理论和实践依据。结果表明，样地中有190个物种具有萌生现象，平均每公顷1830.67株萌生个体；不同生境类型间萌生能力差异明显，总体表现为山顶周围萌生能力较强，山坡周围萌生能力较弱，此外萌生能力的生境关联性还与萌枝的径级大小有关；萌生能力与海拔、凹凸度、坡度和坡向的余弦值显著正相关，而与个体胸高断面积之和显著负相关；样地常见萌生物种的萌生能力有显著但较弱的谱系信号。