Survival and growth of stump sprouts in canopy gaps: A seven-year study in a temperate secondary forest

Abstract

Gap-based silviculture in temperate forests is particularly important to improve forest regeneration and maintain forest ecosystem services. Resprouting is a common regeneration mode after gap formation. However, little is known about its potential to improve the restoration of secondary forests in gap-based silviculture. During a 7-year study (2015–2021), we selected several stumps of six tree species from eight large-medium artificial gaps (476–984 m²) of secondary forests to determine stump sprout dynamics in relation to tree species, stump diameter, and canopy openness. The final stump survival rate for each species exceeded 65 %. The stump sprouts of the six species presented a self-thinning process over 7 years, and the stump sprouts mainly occurred in the first three growing seasons after gap creation (2015–2017). With increasing time after gap creation, all six tree species showed a similar growth pattern, i.e., rapid growth in the first three growing seasons and slow growth in the last two growing seasons (2020–2021). Stump diameter was more likely to correlate with the number of sprouts per stump than canopy openness for all six tree species. For Quercus mongolica and Acer pictum subsp. mono, both stump diameter and canopy openness showed strong relationships with sprout growth in most growing seasons. Throughout the study period, the highest total contributions of stump diameter and canopy openness to sprout density and growth were approximately 50 %. Therefore, determining the appropriate stump diameter and canopy openness for specific species within gaps is beneficial for promoting stump resprouting and can enrich the application of post-logging stump resprouting in gap-based silviculture in secondary forests.