Seed Regeneration Potential of Canopy Gaps at Early Formation Stage in Temperate Secondary Forests, Northeast China

Abstract

Promoting the seed regeneration potential of secondary forests undergoing gap disturbances is an important approach for achieving forest restoration and sustainable management. Seedling recruitment from seed banks strongly determines the seed regeneration potential, but the process is poorly understood in the gaps of secondary forests. The objectives of the present study were to evaluate the effects of gap size, seed availability, and environmental conditions on the seed regeneration potential in temperate secondary forests. It was found that gap formation could favor the invasion of more varieties of species in seed banks, but it also could speed up the turnover rate of seed banks leading to lower seed densities. Seeds of the dominant species, Fraxinus rhynchophylla, were transient in soil and there was a minor and discontinuous contribution of the seed bank to its seedling emergence. For Quercus mongolica, emerging seedling number was positively correlated with seed density in gaps (R = 0.32, P<0.01), especially in medium and small gaps (<500 m2). Furthermore, under canopies, there was a positive correlation between seedling number and seed density of Acer mono (R = 0.43, P<0.01). Gap formation could promote seedling emergence of two gap-dependent species (i.e., Q. mongolica and A. mono), but the contribution of seed banks to seedlings was below 10% after gap creation. Soil moisture and temperature were the restrictive factors controlling the seedling emergence from seeds in gaps and under canopies, respectively. Thus, the regeneration potential from seed banks is limited after gap formation.

Gap closure process by lateral extension growth of canopy trees and its effect on woody species regeneration in a temperate secondary forest, Northeast China

“…The frost-free period is about 130 days (Zhu et al 2014b). The predominant soil is a clay loamy soil (sand: 25.6%, silt: 51.2%, clay: 23.2%) (Yan et al 2012). Most of the forests at Qingyuan Forest CERN, CAS grew after a complete fire disturbance in 1950s, forming a typical secondary forest ecosystem.…”

Different light acclimation strategies of two coexisting tree species seedlings in a temperate secondary forest along five natural light levels

“…Although these two species regenerate successfully in old growth forests, they were reported to have poor regeneration performance in the natural secondary forests . Many efforts, therefore, have been made to improve their regeneration (Yan et al, , 2012. In the temperate forests, light plays a key role in the natural regeneration and succession of many tree species (Nicotra et al, 1999) because the light environments are always changing either in predictable ways (within a day, between seasons) or in unpredictable ways (caused by weather or forest canopy dynamics) (Veneklaas and den Ouden, 2005).…”

Comparison of gap formation and distribution pattern induced by wind/snowstorm and flood in a temperate secondary forest ecosystem, Northeast China

“…forests until the 1930s. After decades of timber harvest and massive controlled burns disturbances, the old-growth mixed broadleaved-Korean pine forests had been replaced by the secondary forests (Yan et al 2012). During 1960s, some of the secondary forests were replaced by larch plantations to meet the timber demand (Yang et al 2012).…”