Abstract:

Aims: Data-based knowledge of species diversity distribution in natural reserves is fundamental for the adaptive protection and management of natural reserves. However, species diversity patterns have been rarely examined comprehensively across the entire areas of majority of natural reserves. This study aims to explore spatial variation in woody species diversity across the Qianjiangyuan National Park, as well as among subareas based on functional divisions.

Methods: A total of 663 plots, each measuring 20 m × 20 m, were surveyed across the national park. Within these plots, all individuals of DBH (diameter at breast height) ≥ 1 cm were identified to species and measured for DBH. Using this comprehensive dataset, we analyzed and presented the spatial pattern in observed species richness, rarefaction species richness, cross-sectional area at breast height (A_DBH), and the number of tree individual number across the national park. Furthermore, we compared those variables among subareas based on functional divisions, emplying various statistical comparison techniques such as z-test, Max-t test, Siegel-Tukey test, and Fligner-Killeen test. These analytical methods allowed us to explore and understand the difference in the aforementioned variables between different functional divisions within the national park.

Results: The distribution of hotspots for woody species diversity basically matched core protection areas of the national park. Among the subareas, the Gutian subarea (GTs), Changheqi subarea (CHQs), and Gutian-Suzhuang subarea (GSs) showed the highest levels of observed and rarefaction species richness. There were no significant differences in observed species richness among these three subareas, and rarefaction species richness was also statistically similar for GTs and GSs, both of which were higher than CHQs. The variations in species richness indices were the smallest for GTs and GSs. Regarding the A_DBH, the Qixi subarea (QXs), CHQs, and GTs had the largest values, with no significant difference among them. However, GSs had a significantly smaller A_DBH compared to CHQs and GTs. The subareas GTs and GSs had the lowest number of tree individuals. As for the Changhong and Hetian towns, the Changhong-Hetian subarea (CHs) and Gutian-Hongyuan subarea (GHs) exhibited the smallest in both species richness and A_DBH.

Conclusion: In conclusion, our findings support the basic reasonability of the functional divisions within the national park in terms of biodiversity. We have identified important biodiversity hotspots and conservation gaps: the GTs stands out as having the largest trees and the highest woody species richness. Adjacent to GTs, the GSs exhibits similar species richness but with smaller trees. Integrating GSs into the core protection area would be beneficial for safeguarding the overall integrity of the main ecosystem's integrity in the national park; within the CHQs, the part encompassing Changhong and Hetian towns showed poor woody species diversity, with small trees and high human-disturbance. These areas require strengthened protection and restoration efforts to enhance biodiversity; CHs and GHs displayed low species richness, characterized by small trees and strong human-disturbance. In these regions, it is essential to establish synergies between community development and biodiversity protection to promote conservation. By extending knowledge of biodiversity hotspots and conservation gaps, our study provides valuable support for the adaptive protection and management of biodiversity within the national park. Our findings can be used to guide targeted conservation strategies and ensure the sustainable protection of the park's unique ecological treasures.

Key words: observed species richness, rarefaction species richness, subtropical evergreen broad-leaved forest, biodiversity conservation, functional division, biodiversity hotspot