Regeneration Characteristics and Spatial Pattern of <i>Platycladus orientalis</i>in Mount Tai, China

Platycladus orientalis is one of the main tree species in Mount Tai, and its sustainable development is of great significance to the protection and development of the forest ecological environment of Mount Tai. In this study, a representative sample plot of Platycladus orientalis with a size of 30 m * 20 m was selected on Mount Tai. The growth and distribution of the parent trees and seedlings of Platycladus orientalis were investigated in the sample plots. The results showed that both the mother cypress trees and seedlings inside the plot present an aggregated distribution pattern within a certain scale, which conforms to the distribution of most natural communities;and the mother cypress can promote seedlings within a certain scale. Although Platycladus orientalis has good natural regeneration ability, it is difficult to succeed in understory regeneration solely relying on natural fertility, and it is not conducive to the long-term stable development of forest stands. Therefore, the thinning of Platycladus orientalis and the adjustment of the forest stand structure and artificial promotion of natural regeneration can not only reduce operating costs, but also conform to the idea of forest near-natural management and maintain sustainable forest development.

树种菌根类型通过细根生物量和凋落物动态影响土壤呼吸和土壤碳储存

热带森林是高生产力但同时也是脆弱的生态系统之一。一些全球范围的造林项目计划未来十年在热带地区种植数百万棵树。树种菌根类型影响森林土壤碳储存已成为共识,但在热带地区,树种菌根类型如何影响土壤呼吸(Rs)和碳储存,目前仍知之甚少。为研究树种菌根类型对Rs和土壤碳储存的影响,本实验在一个近30年热带同质园的3种丛枝菌根(AM)树种和3种外生菌根(EM)树种的单种林中,测量了其Rs和表层20 cm的碳含量,以及有关的生物因子(如根生物量、凋落物动态、土壤微生物)和非生物因子(如微气候)。研究结果表明,AM单种林的Rs、土壤碳含量,以及凋落物周转速率和细根生物量显著高于EM单种林。分析表明,与其他生物和非生物因子比较,树种菌根类型对Rs和土壤碳含量的影响最大。进一步分析表明,菌根类型是通过细根生物量和凋落物动态(凋落物产量、凋落物现存量、凋落物周转速率)直接和间接影响Rs和土壤碳含量。本研究结果强调了树种菌根类型对森林碳循环的影响,表明在热带地区种植AM树种可能比种植EM树种更能促进土壤固碳。