Herbaceous plants are an essential component of forest diversity and driver of ecosystem processes. However, because the growth forms and life-history strategies of herbaceous plants differ from those of woody plants, it is unclear whether the mechanisms that drive patterns plant diversity and community structure in these two plant groups are the same. In this study, we determined whether herb and woody plant communities have similar patterns and drivers of alpha- and beta-diversity. We compared species richness, distribution, and abundance of herbs to woody seedlings in a 20-ha Donglingshan warm-temperate forest (Donglingshan FDP), China. We also determined whether variation in patterns of species richness and composition are better explained by environmental or spatial variables. Herbaceous plants accounted for 72% of all species (81 herbaceous, 31 woody) recorded. Alpha- and beta-diversity were higher in herbs than in woody seedlings. Although alpha-diversity of herbs and woody seedlings was not correlated across the site, the local-site contributions to beta-diversity for herbs and woody seedlings were negatively correlated. Habitat type explained slightly more variation in herb community composition than in woody seedling composition, with the highest diversity in the low-elevation slope. Environmental variables explained the variation in species richness and composition more in herbaceous plants than in woody seedlings. Our results indicate that different mechanisms drive variation in the herb and woody seedling communities, with herbs exhibiting greater environmental sensitivity and habitat dependence. These findings contribute to the better understanding of herbaceous plant diversity and composition in forest communities.

Subtropical natural forests are unique due to their ecological and economic functions. However, most of these forests are highly degraded, which impairs the ability to provide ecological and economic benefits. Enrichment planting is an important approach to restore natural degraded forests. Species arrangement is of great importance to inform enrichment planting. Species association refers to the interrelationship of different species occupying a habitat and is a static description of the organic connection formed by the interaction of species. Species association, therefore, provides a scientific basis for species arrangement in enrichment planting. Additionally, because an old-growth forest is a climax community that has attained great age without significant disturbance, the species association in an old-growth forest can provide valuable information on the reference conditions for forest management. In this study, the species association between dominant tree species (including saplings and adult trees) was investigated in an old-growth forest in the Gutianshan National Nature Reserve in Zhejiang province in subtropical China. The objective of the study was to inform species arrangement for enrichment planting. The result showed that the overall species association exhibited a significant net positive association, indicating a dynamic balance of stable structure and species composition in the old-growth forest. Additionally, the pairwise species association was examined using the χ² test, the Dice index, and Spearman’s rank correlation coefficient; significant positive and negative pairwise species associations were detected. Based on the species association and the light requirements of the tree species, an optimal species arrangement was determined to support enrichment planting for restoring natural degraded forests. It is expected that the results of this study will contribute to the restoration of natural degraded forests in subtropical China.

Species richness and diversity substantially affect forest structures and function and are critical indicators of sustainable forest management. Sampling surveys are widely used in forest inventories because they efficiently assess forest characteristics. However, an appropriate sample plot design is required. The objectives of this study were to evaluate the effects of plot design on estimating species richness and species diversity using a simulation. A 20 ha census plot was established in a temperate forest to obtain the true values of species richness and species diversity. One single plot design and nine cluster plot designs were evaluated. The results indicated significant differences in forest species richness and species diversity for different plot designs. The cluster plot design with a square subplot configuration (SCONFIG) and extent of ground area covered by a cluster (EGROUND) of 500 m² exhibited the best performance (accuracy, precision) in estimating forest species richness. In contrast, a rectangular cluster plot with an EGROUND of 1000 m² was more suitable for assessing species diversity. This study demonstrates that cluster plots outperform a single plot for evaluating species richness and species diversity in temperate forests.