Data from: Canopy disturbance and gap partitioning promote the persistence of a pioneer tree population in a near-climax temperate forest of the Qinling Mountains, China

An unresolved question of temperate forests is how pioneer tree species persist in mature forests. In order to understand the responsible mechanisms, we investigated a near-climax mixed temperate forest dominated by Betula albosinensis in the Qinling Mountains of China. Through establishing four 50 m × 50 m plots, we examined the canopy disturbance characteristics and its effects on tree recruitments. We further test the intra- and interspecific effects on the recruitment of B. albosinensis. The obtained data demonstrated canopy disturbance was frequent but most small-sized. The canopy gaps are caused mainly by adult B. albosinensis by snapping. The regeneration of coexistent tree species shows distinct preference for gap size. B. albosinensis were clumped at the juvenile stage and small scales. B. albosinensis juveniles were positively associated with B. utilis juveniles and negatively associated with the conspecific and B. utilis large trees. In addition, B. albosinensis juveniles showed negative associations with contemporary other tree species. Our results suggested that canopy disturbance caused by canopy trees and gap partitioning among the coexistent tree species are important for the persistence of the mixed forest. As a main gapmaker, B. albosinensis appear to develop a self-perpetuating life-history trait and allow them to persist.

温带森林领域迄今尚未解决的关键科学问题之一，是先锋树种如何在成熟林内实现长期存续。为阐明该现象背后的潜在机制，我们在中国秦岭地区选取了一片以红桦（Betula albosinensis）为优势种的近顶极混交温带林作为研究对象。通过设置4块50 m × 50 m的固定样地，我们调查了林冠干扰的特征及其对林木更新的影响，并进一步分析了种内与种间相互作用对红桦更新的影响。研究数据显示，该林内林冠干扰频发，但多数为小型干扰，林隙主要由成年红桦的枝干折断所形成。伴生树种的更新对林隙大小呈现出显著的偏好性。红桦幼树在小尺度范围内呈聚集分布格局，且与糙皮桦（Betula utilis）幼树呈正相关关系，而与同种成年大树及糙皮桦成年大树呈负相关关系。此外，红桦幼树与同期共存的其他树种均呈负相关关系。本研究结果表明，由冠层优势树木引发的林冠干扰，以及伴生树种间的林隙生态位分化，对该混交林的长期存续至关重要。作为主要的林隙形成者，红桦演化出了自我维持的生活史特征，从而使其能够在成熟林中持续存续。