Variation in three community features across habitat types and scales within a 15‐ha subtropical evergreen‐deciduous broadleaved mixed forest dynamics plot in China

Abstract

The evergreen and deciduous broadleaved mixed forests (EDBMFs) belong to one of the ecosystems most sensitive to environmental change, however, little is known about the environmental determinants for their plant diversity and forest structure at different habitat types and spatial scales. Here, we used data from a 15‐ha (300 × 500 m) forest dynamic plot (FDP) of an old‐growth EDBMF to examine the patterns and determinants of the three community features (stem abundance, rarefied species richness and basal area [BA]) in three habitat types (ridge, hillside and foothill) and at three spatial scales (20 × 20 m, 50 × 50 m, and 100 × 100 m). We found that the three community features significantly changed with habitat type, but only one of them (rarefied richness) changed with scale. Among spatial scales, the principle environmental factors that widely affected community features were pH, soil organic matter, and total phosphorus, while these effects only taken place at certain habitat. Variations in the three community features explained by soil conditions were generally greater than those explained by topographical conditions. With changes in habitat type, the proportion of variations explained by environmental conditions was 31%–53%, 8%–25%, and 18%–26% for abundance, rarefied richness, and BA, respectively. With increasing spatial scale, the variations explained by environmental conditions were 44%–75% for abundance, 28%–95% for rarefied richness, and 18%–86% for BA. Our study demonstrated that environmental factors had great impacts on the plant diversity and forest structure in the EDBMFs, especially the soil factors such as pH. In addition, the importance of the environmental determinants on these community features was highly related to the spatial scale.

Ecological uniqueness of species assemblages and their determinants in forest communities

“…the Hnjfl FDP) in the north‐western corner of the 60‐ha FDP. The Hbmlz FDP (300 × 200 m) is located in the Mulinzi National Nature Reserve, southwest Hubei Province, Central China (29°55′59″–30°10′47″N, 109°59′30″–110°17′58″E), which represents an old‐growth subtropical evergreen and deciduous broadleaved mixed forest (SEDBMF, Feng et al., 2018). The Gsxls FDP is located in the Xiaolong Mountain National Nature Reserve (33°35′12″–33°45′11″N, 106°13′10″–106°33′06″E) in the west of Qinling Mountain, south‐eastern Gansu Province, China, and it represents an old‐growth warm temperate deciduous forest (WTDF).…”