Lack of tree layer control on herb layer characteristics in a subtropical forest, China

Abstract

Question: Knowledge of the interaction between understorey herb and overstorey tree layer diversity is mostly restricted to temperate forests. How do tree layer diversity and environmental variables affect herb layer attributes in subtropical forests and do these relationships change in the course of succession? Do abundance and diversity of woody saplings within the herb layer shift during succession? Location: Subtropical broad‐leaved forests in southeast China (29°8′18″‐29°17′29″N, 118°2′14″118°11′12″E). Methods: A full inventory of the herb layer including all plants below 1‐m height was done in 27 plots (10 × 10 m) from five successional stages (<20, <40, <60, <80 and ≥80 yr). We quantified the contribution of different life forms (herbaceous, woody and climber species) to herb layer diversity and productivity and analysed effects of environmental variables and tree layer diversity on these attributes. Results: Herb layer composition followed a successional gradient, as revealed by non‐metric multidimensional scaling (NMDS), but diversity was not correlated to the successional gradient. There was no correlation of diversity across layers. Herb layer productivity was neither affected by tree layer diversity nor by herb layer diversity. Although abundance of woody species in the herb layer decreased significantly during succession, woody species contributed extraordinarily to herb layer species diversity in all successional stages. All environmental factors considered had little impact on herb layer attributes. Conclusions: The subtropical forest investigated displays an immense richness of woody species in the herb layer while herbaceous species are less prominent. Species composition of the herb layer shows a clear successional pattern, however, the presence or absence of certain species appears to be random.

Higher β‐diversity observed for herbs over woody plants is driven by stronger habitat filtering in a tropical understory

“…Within the BCI plot, sampled quadrats that had high or low levels of richness/diversity, as well as quadrats that had unique species compositions, were not the same for herbaceous and woody communities. A similar result was reported from a subtropical forest in China by Both et al (2011), although their results come from a much larger study area, and used adult canopy trees (Both et al 2011). This has been attributed to landscape-to geographic-scale variation in climate and soil fertility that impacts both herbaceous and woody communities in similar ways.…”

“…Life-history strategies among herbs are also more diverse than for trees, so studying trait diversity of tropical herbaceous systems would be highly informative (Bierzychudek 1982, Both et al 2011. Despite contributing less to overall biomass and diversity than in temperate regions, tropical herbs still account for a large proportion of total species richness.…”

Kinetic Energy of Throughfall in Subtropical Forests of SE China – Effects of Tree Canopy Structure, Functional Traits, and Biodiversity

“…However, a direct link between herb- and tree-layer diversity could not be found in the study area [48]. Nevertheless, regarding the soil itself, [28] showed that soils in highly diverse forests are characterized by a higher rooting density (mechanism 3, cf.…”

Belowground top-down and aboveground bottom-up effects structure multitrophic community relationships in a biodiverse forest

“…At the same time, herb layer plant communities were surveyed with abundance and cover estimates in the central 10 m × 10 m of each plot (<1 m height 41 ).…”