Abstract
Seedling and sapling spatial patterns are important in community regeneration, and understanding the natural regeneration mechanisms of tree species in relation to spatial patterns will help improve forest management and community restoration efficiency. Based on data from three fixed plots established in birch forests (BF), coniferous and broadleaved mixed forests (CBMF) and coniferous mixed forests (CMF) in the central Greater Khingan Mountains in Heilongjiang Province, China, in 2017, we used the univariate and bivariate O-ring functions of the point pattern analysis method to evaluate the spatial patterns and associations of the main tree species in these three forest types at different development stages and identified the community successional stages according to the interspecific associations between dominant tree species and other tree species. The results showed that Betula platyphylla and Larix gmelinii in BF exhibited identical spatial distribution patterns and had a tendency to transition from an aggregated to a random distribution from saplings to adult trees, whereas every tree type in CBMF generally showed a random distribution. Adult trees of the main tree species in CMF, i.e., L. gmelinii and Picea koraiensis, mainly showed a random distribution, but P. koraiensis at other size classes generally showed an aggregated distribution. The intraspecific associations of the main tree species in BF and CMF at different development stages were constrained by the spatial scale within a given scope, while those in CBMF at different development stages were not significantly constrained by spatial scale. The results also show that the density of the three forest types was affected by the distance between the individuals of the various tree classes and adult trees, with different levels of influence. We analyzed the interspecific associations between dominant tree species and other tree species and then assessed community succession progress and found that the BF and CMF exhibited medium-term community succession, while the CBMF was in the primary stage. Our results further show that the spatial distribution patterns of the tree species in the small-diameter classes were jointly affected by adjacent habitats and diffusional limitations and that scale dependence existed in the intraspecific and interspecific associations. The analysis of the natural regeneration of spatial distribution and interspecific associations represents an efficient way to explore the stability of forest communities and dynamic changes in interspecific relationships during succession. The study results thus provide a theoretical basis for developing rational forest management measures.
Highlights
A natural secondary forest is forest that has regenerated as a result of natural processes after the original forest vegetation has been significantly disturbed at some point in time or, over a longer period of time
In the coniferous and broadleaved mixed forests (CBMF), the results showed that there was a positive association between small trees and saplings of B. platyphylla at small scales (1–2 m), and they were not associated at the subsequent scales, saplings of B. platyphylla at small scales (1–2 m), and they were not associated at the subsequent scales, while the density of saplings gradually decreased and stabilized with an increasing distance from while the density of saplings gradually decreased and stabilized with an increasing distance from the the small trees of B. platyphylla and increased slightly at larger scales (45–50 m, Figure 6, Bp3–Bp2)
The saplings, small trees, and medium-sized trees of L. gmelinii in the three types of forest showed an aggregated distribution at a small scale, which is related to the dispersal properties of its seeds; the seeds are mainly affected by the force of gravity since they have a large mass, a significantly aggregated distribution occurred at locations near the mother tree at a small scale
Summary
A natural secondary forest is forest that has regenerated as a result of natural processes after the original forest vegetation has been significantly disturbed at some point in time or, over a longer period of time. A secondary community forms through secondary succession, and degradation of the ecological system of the original forest occurs [1,2]. Having the characteristics of multiple tree species and a wide distribution scope [3], a natural secondary forest is an important production base of forest byproducts, timber and fuelwood and plays an important role in water conservation, climate regulation and the maintenance of ecological balance [4,5]. 1990–2015, the area of natural secondary forest around the world increased by 2.315 billion ha (56.08%). According to the results of the Eighth National Forest
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
