Abstract
Studying the spatial pattern of plant species may provide significant insights into processes and mechanisms that maintain stand stability. To better understand the dynamics of naturally regenerated secondary forests, univariate and bivariate Ripley’s L(r) functions were employed to evaluate intra-/interspecific relationships of four dominant tree species (Populus davidiana, Betula platyphylla, Larix gmelinii and Acer mono) and to distinguish the underlying mechanism of spatial distribution. The results showed that the distribution of soil, water and nutrients was not fragmented but presented clear gradients. An overall aggregated distribution existed at most distances. No correlation was found between the spatial pattern of soil conditions and that of trees. Both positive and negative intra- and interspecific relationships were found between different DBH classes at various distances. Large trees did not show systematic inhibition of the saplings. By contrast, the inhibition intensified as the height differences increased between the compared pairs. Except for Larix, universal inhibition of saplings by upper layer trees occurred among other species, and this reflected the vertical competition for light. Therefore, we believe that competition for light rather than soil nutrients underlies the mechanism driving the formation of stand spatial pattern in the rocky mountainous areas examined.
Highlights
Secondary forests comprise woody vegetation that recovers naturally after a complete anthropogenic forest clearance [1, 2]
Larix was taller and larger than the other three species (Table 1); the quantity composition showed that the height and DBH peaks of Larix were biased towards the upper end (Fig 2)
We studied and analyzed the size structure, spatial pattern and driving mechanism of the spatial pattern of a secondary forest to generate practical guidelines for future reference of the sustainable management of similar forest ecosystems
Summary
Secondary forests comprise woody vegetation that recovers naturally after a complete anthropogenic forest clearance [1, 2]. They are valuable remnants as they are vitally important in biodiversity conservation, water conservation, soil erosion control and carbon sequestration. These values of secondary forests have been realized [3] and increasing attention has been paid to the management of such forests.
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