Seedling recruitment in response to artificial gaps: predicting the ecological consequence of forest disturbance

Abstract

Artificial gaps are widely created for forest management. However, the interactive effects of gap sizes and within-gap locations on seedling regeneration are rarely tested. Therefore, whether there are lower and upper size limits for artificial gaps remains controversial. Here, we aimed to test the hypothesis that the effects of within-gap positions on seedling regeneration are dependent on gap sizes. Newly germinated wild seedlings of shade-intolerant Quercus mongolica scattered in different positions within artificially created gaps of different sizes were surveyed to test our hypothesis. Large gaps promoted seedling growth more than medium and small gaps. The increase in Q. mongolica seedling growth in large gaps can be largely attributed to the dormancy breaking of the apical buds and increased net photosynthetic rates. More importantly, we showed that the effects of within-gap position were prominent only in medium gaps, i.e., the effect of within-gap position appears to be dependent on gap size. We show an integrative effect of gap size and within-gap location on seedling performance of shade-intolerant oaks, suggesting future studies should evaluate the influence of within-gap location in conjunction with the role of gap size. We therefore suggest that gap creation in silvicultural systems should highlight the lower and upper size limits of forest gaps, which will vary with the species and regions studied.