Karst tiankengs as refugia for indigenous tree flora amidst a degraded landscape in southwestern China

Abstract

We conducted floristic and community analyses to compare the floristic composition, forest structure, taxonomic richness, and species diversity between two tiankeng (large doline, or sinkhole) habitats and two outside-tiankeng habitats of forest fragments in a degraded karst area in southwestern China. We found remarkably higher taxonomic richness in the tiankeng habitats than in the outside-tiankeng habitats at the species, generic, and familial levels. The inside-tiankeng habitats had higher floristic diversity but lower dominance. The remarkably higher uniqueness at all taxonomic levels and the much larger tree size in the two tiankeng habitats than in the outside-tiankeng habitats demonstrated the old-growth and isolated nature of the tiankeng flora. Plot-scale species richness, Shannon-Wiener index, Pielou’s evenness, and Berger-Parker dominance significantly differed across habitats. Heterogeneity in floristic composition at the species, generic, and familial levels was extremely significant across habitats. In pairwise comparisons, except for the Chuandong Tiankeng-Shenmu Tiankeng pair, all the pairs showed significant between-habitat heterogeneity in floristic composition. Our results suggest that as oases amidst the degraded karst landscape, tiankengs serve as modern refugia that preserve old-growth forest communities with their rich floristic diversity, and can provide a model for habitat conservation and forest restoration in that area.

Community Attributes Predict the Relationship between Habitat Invasibility and Land Use Types in an Agricultural and Forest Landscape

“…Rank-abundance plot, also called diversity-dominance curve, visualizes the community dominance and evenness as well as species richness of an ecosystem in a two-dimensional graph. A steeper curve indicates greater community dominance and less evenness of species patterns in an ecosystem [37,38].…”

Plant ecology of tropical and subtropical karst ecosystems

“…Arable lands are confined to valleys, foothills, and soil‐filled sinkholes in karst regions, and they are the first to be converted to farmlands and homesteads (Su et al . ). Historically, people did not cultivate karst hilltops and upper slopes where water and nutrients were lacking, but land shortage and development policies have caused deforestation even in upper slopes and hilltops (Yan & Cai ).…”

Effects of environmental factors and heavy metals on the vertical distribution of bryophytes in a sinkhole environment

“…Sinkholes have complex environmental characteristics because of their unique geomorphology (Zhu et al 2003;B atori et al 2014;Shui et al 2015;Su et al 2017;Hofierka et al 2018). Environmental researchers have found that sinkholes have the potential to act as a geophysical well for higher concentrations of contaminant deposition from traffic (Theodore et al 2008;Wang et al 2009;Kong et al 2011Kong et al , 2012Liu & Zhang 2019).…”