Selective logging destabilizes the functioning and composition of forest ecosystems at multiple spatial scales

Selective logging is one of the most prevalent land uses of forests worldwide, affecting biodiversity and ecosystem functioning. However, the effect of selective logging on the dual nature of temporal stability, and the scale dependence of this effect, remain to be elucidated. By conducting several decade-long experiments in temperate forest ecosystems, we tested the effects of selective logging on aggregate and compositional stability at multiple spatial scales. As expected, forest ecosystem stability at larger spatial scales was enhanced both by the stability of local scales (i.e. α stability) and asynchronous dynamics among local communities (i.e. spatial asynchrony). We found that the negative effects of selective logging on both facets of forest stability propagated from local to larger spatial scales due to reduced α stability and the biological insurance effects of α diversity. However, both spatial aggregate and compositional asynchrony were not affected by selective logging. Interestingly, despite the selective logging, α diversity still provided biological insurance effects for maintaining aggregate and compositional stability. Our results imply that selective logging may destabilize the aggregate ecosystem functioning and species composition of forest ecosystems at local and larger spatial scales. To our knowledge, this study provides the first evidence of the scale dependence of aggregate and compositional stability of forest ecosystems in response to selective logging. Our findings suggest that forest management should avoid excessive selective logging and strive to protect forest diversity to safeguard the sustainability of the functioning and composition of natural forest ecosystems at multiple spatial scales.

选择性采伐（selective logging）是全球森林最普遍的土地利用方式之一，会对生物多样性及生态系统功能产生影响。然而，选择性采伐对时间稳定性双重特质的影响，以及该影响的尺度依赖性，仍有待阐明。本研究通过在温带森林生态系统中开展长达数十年的野外实验，探究了选择性采伐对多空间尺度下群落整体稳定性（aggregate stability）与群落组成稳定性（compositional stability）的影响。正如预期，大空间尺度下的森林生态系统稳定性，可通过局地尺度稳定性（即α稳定性（α stability））与局地群落间的异步动态（即空间异步性（spatial asynchrony））得到提升。研究发现，由于α稳定性降低以及α多样性（α diversity）的生物保险效应，选择性采伐对森林稳定性两个维度的负面影响会从局地尺度传递至更大的空间尺度。但空间整体异步性与组成异步性均未受到选择性采伐的影响。值得注意的是，即便经历了选择性采伐，α多样性仍能发挥生物保险效应，助力维持群落整体与组成稳定性。本研究结果表明，选择性采伐可能会降低局地及大空间尺度下森林生态系统的整体功能与物种组成的稳定性。据我们所知，本研究首次证实了森林生态系统整体与组成稳定性对选择性采伐的响应存在尺度依赖性。本研究结果提示，森林经营应避免过度选择性采伐，并致力于保护森林生物多样性，以保障多空间尺度下天然森林生态系统功能与组成的可持续性。