Coverage of Native Plants Is Key Factor Influencing the Invasibility of Freshwater Ecosystems by Exotic Plants in China.

Shufeng Fan,Haihao Yu,Chunhua Liu,Ligong Wang

doi:10.3389/fpls.2018.00250

Abstract

Understanding the biotic and abiotic factors that influence the susceptibility of a community to invasion is beneficial for the prediction and management of invasive species and the conservation of native biodiversity. However, the relationships between factors and invasibility of a community have not been fully confirmed, and the factors most associated with the susceptibility of a community to invasion have rarely been identified. In this study, we investigated the species richness patterns in aquatic exotic and native plants and the relationships of exotic species richness with habitat and water environment factors in 262 aquatic plant communities in China. A total of 11 exotic plant species were recorded in our field survey, and we found neither a negative nor a positive relationship between aquatic exotic and native plant species richness. The aquatic exotic plant species richness is negatively correlated with the relative coverage and biomass of native plants but positively correlated with the total nitrogen (TN), total phosphorus (TP), and chemical oxygen demand (COD) concentrations in the water. The native plant species richness, native species’ relative coverage, and native species’ biomass were positively related to each other, whereas the TP, TN, and COD were also positively related to each other. The native plant species richness, native species’ relative coverage, and native species biomass were each negatively correlated with the TP, TN, and COD. In addition, biotic rather than abiotic predictors accounted for most of the variation in exotic plant richness. Our results suggest that improving the vegetation coverage and the biodiversity of native plants is the most effective approach for preventing alien plant invasions and minimizing their impacts on freshwater ecosystems.

Highlights

Plant invasions reduce biodiversity and alter the species composition, structures, processes, and functions of invaded ecosystems (Vitousek, 1990; D’Antonio and Kark, 2002; Vilà et al, 2011)
We investigated the relationships among native plant richness, native vegetation coverage, native vegetation biomass, water nutrition [total nitrogen (TN) and total phosphorus (TP) concentrations], pollution level [chemical oxygen demand (COD)], habitat size, latitude, and exotic plant richness, and determined the correlations among these factors in the freshwater ecosystems of China
The exotic plant species richness was positively related to the TP (r = 0.251, P < 0.001) (Figure 2D), TN (r = 0.220, P < 0.001) (Figure 2E), and COD (r = 0.185, P < 0.005) (Figure 2F) of the water

Summary

Introduction

Plant invasions reduce biodiversity and alter the species composition, structures, processes, and functions of invaded ecosystems (Vitousek, 1990; D’Antonio and Kark, 2002; Vilà et al, 2011). Communities with high biodiversity are considered more capable of resisting invasions (Elton, 1958; Kennedy et al, 2002) because more species produce stronger competition pressure and more fully occupy the available niche space, thereby limiting the opportunities for additional species to establish and survive (Elton, 1958; Levine and D’Antonio, 1999; Shea and Chesson, 2002). Previous studies have reported that native and exotic species richness values are positively related at both the local and the landscape scales (Davies et al, 2007; Souza et al, 2011), no relationship between native and invasive species richness has been found (Capers et al, 2007)

Methods

Results

Discussion

Conclusion