基于功能多样性探究种间竞争对东灵山草本多样性海拔格局的影响

The elevational richness pattern has been a central research theme of ecology and biogeography, however, until now, the cause of elevational richness pattern has remained unclear. One of the reasons is the past studies only focused on the role of climate or spatial factors, the role of biotic interaction had been ignored. A number of studies indicated that biotic interaction, competition especially, can significant change the community structure. In forest, specifically, overstory species can shape the herb community by control light availability, according to our previous study, we hypothesize this biotic filter (light-mediated plant-plant interaction) shapes the herb richness at low elevations and is part of the reason for the “hump-shaped” richness pattern: herb richness is lower in low elevation because the dense overstory cover, only small subsets of species can tolerate the low-light availability conditions. As elevation increases, overstory cover became sparser while species richness increases because shade-intolerant species are relieved from the light limitation. While at high elevations, low temperatures may act as a filter in removing the species that lack the ability for persisting under cold and long frost conditions. The mid-elevations offer minimum biotic stress and moderate abiotic stress, thus more species can survive under such benign conditions. environmental change would significantly. To prove our hypothesis, we take herb as the study object and employ functional diversity and statistical model to assess the importance of overstory over for elevational richness pattern. The aim of this study is to understand the role of environmental fluctuation on elevational richness pattern in long time scale. We expect it would not only provide a new insight on understanding causes of elevational richness pattern, but also provide decision-making support for conservation of biodiversity.

物种多样性海拔格局是生态学的热点问题之一，然而针对其成因的研究大多集中于环境与空间因子，对生物因子的探讨较少。基于已有文献及申请人前期研究，本研究假设种间竞争（树木遮阴）可以成为草本单峰型多样性海拔格局的驱动力：低海拔地区树木遮阴较强，只有耐阴物种才能生存，导致草本多样性较低，随着海拔升高，遮阴逐渐减弱因而多样性有所升高，而在高海拔地区，环境压力限制了草本多样性。中海拔地区具有最低的竞争压力和适度的环境压力，因此拥有最高的多样性。功能属性可以反映物种适应环境所采取的策略，基于其多样性的分析有助于揭示群落结构的主要驱动因子。为证实以上假说，本研究以东灵山草本植物为研究对象，利用分析功能多样性和统计建模相结合的研究方法，揭示树木遮阴对草本植物多样性海拔格局的影响。本研究旨在为理解多样性海拔格局的形成机制提供新视角，为多样性保护提供理论支持。

山地生态系统具有丰富的生物多样性资源，在陆地生态系统中，约有85%的物种栖息于山地，其中一半以上为山地特有种。然而，虽然经历了几十年的研究 ，生物多样性海拔格局的形成机制依然不清楚。本研究通过构建分形几何模型对多样性海拔格局进行meta分析，提出了能量需求假说。本研究对全球41座山脉14大类群（鸟类、直翅目、鞘翅目、鳞翅目、蜜蜂、蚂蚁、乔木、灌木、草本、蕨类、土壤层动物、凋落层动物、真菌和细菌）的多样性海拔格局进行了分析，结果表明基于能力理论的分形几何模型可以很好地预测不同类群能力需求与多样性格局变化之间的关系（R2=0.71***）。说明尺度选择对于多样性海拔格局的非常重要。本研究更进一步地利用东灵山的乔木、草本和凋落物层动物验证尺度选择的重要性，结果表明在本模型模拟得到的尺度下能够较好的预测多样性的海拔格局。同时，本研究对全球的植物(乔木、灌木和草本）多样性海拔格局进行了分析，发现虽然在不同气候区植被的多样性海拔局的驱动因子有所不同，但其形成机制都可以归纳为能量限制：在对位于全球17座山脉的52个植被多样性海拔格局数据进行分析后，发现约76%的多样性格局的主要驱动因子与能量限制有关。说明虽然多样性海拔格局虽然因山地和类群的不同而不同，但是其形成机制可能是一致的。本研究提出了针对多样性海拔格局的统一模型，认为能量限制是驱动多样性沿海拔变化的最重要原因，并构建了基于分形几何理论的多样性格局模型用以模拟尺度选择对了解多样性格局驱动因子的影响，有利于进一步加深对多样性海拔格局形成机制的理解，为生物多样性保护和管理提供理论支持。