Spatial Distribution Pattern and Association of Sapindus saponaria in Fengshui Forest, Leizhou Peninsula

Abstract:

To explore the application of Sapindus saponaria in ecological restoration and urban garden, a 1 hm² plot was set up in S. saponaria Fengshui Forest in Zorong Village, Longmen Town, Leizhou City, Guangdong Province, the species composition of community was analyzed, and its spatial distribution pattern and intraspecific correlation were also analyzed using a point pattern analysis with complete spatial randomness and heterogeneous poisson. The results showed that there were 3 585 individuals of 73 species, belonging to 60 genera and 28 families with diameter at the breast height (DBH) ≥ 1 cm. The proportion of the monogeneric family, single-species family and monotypic genus were obviously higher than other types, followed by the oligogenera families, oligospecies families and oligotypic genera. The spatial distribution patterns of S. saponaria showed an alternating phenomenon of aggregation, random distribution and uniform distribution at 0-25 m scales. At a small scale, the distribution of saplings was aggregated, and that of adults was uniform. With the increment of spatial scale, trees in three age classes were mainly randomly distributed. The saplings and middle-aged trees had a weak positive association at 0-25 m scales, while it was negatively associated between saplings and adult trees. The association between middle-aged and adult trees showed periodic changes, from no significant association (0-4.5 m scale) to positive association (4.5-10.0 m scale) to no association (10.0-25.0 m scale). As a consequence of neighbor competition and density dependence, the spatial distribution pattern of S. saponaria changed from aggregated distribution at small scale to random distribution at large scale. The coexisting proportion of saplings and middle aged trees was high, and that of middle-aged and adult trees at small scales also high, while saplings and adult trees are relatively independent. Therefore, S. saponaria could be cultivated in small aggregations and scattered in large scales for the ecological restoration and urban garden construction in Leizhou Peninsula.