Curvilinear effects of invasive plants on plant diversity: plant community invaded by Sphagneticola trilobata.

Shan-Shan Qi,Dao-Lin Du,Qiong-Xin Zhong,Chun-Can Si,De-Li Zhai,Ping Huang,Rui-Ping Wang,Si-Chong Chen,Zhi-Cong Dai,Fei-Hai Yu

doi:10.1371/journal.pone.0113964

Shan-Shan Qi, Dao-Lin Du + Show 8 more

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https://doi.org/10.1371/journal.pone.0113964

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Abstract

The effects of invasive plants on the species diversity of plant communities are controversial, showing either a positive or negative linear relationship. Based on community data collected from forty 5 m×5 m plots invaded by Sphagneticola trilobata in eight cities across Hainan Island, China, we found S. trilobata decreased plant community diversity once its cover was beyond 10%. We demonstrated that the effects of invasive/native plants on the plant diversity of communities invaded by S. trilobata were curvilinear. These effects, which showed peaks under different degrees of vegetation cover, appeared not only for S. trilobata and all invasive plants, but also for all native plants. Invasive plants primarily had negative effects on plant diversity when they became abundant at a much lower cover level (less than 35%), compared with the native plants (over 60%). Thus, it is necessary to distinguish a range for assessing the effects of plants, especially invasive plants. Our results also confirmed that the invasion intensity of invasive alien plants increased with the intensity of local economic development. We highlight and further discuss the critical importance of curvilinear effects of biological invasion to provide ideas regarding the conservation of local biodiversity and the management of invasive plants.

Highlights

Biodiversity is important in the functional provision and stability of ecosystems [1, 2]
The cover values obtained for S. trilobata, the other invasive plants, the alien non-invasive plants, and the native plants ranged from 0.5% to 99%, 0% to 31.5%, 0% to 31%, and 1% to 85.5%, respectively
The changes in plant community diversity in response to the species composition (S. trilobata, all invasive plants and all native plants) were similar, exhibiting a quadratic pattern, but did not present a simple linear relationship (Fig. 3a-c; Table 1). The cover of both all invasive plants and all native plants was a relatively stable predictor of peak plant diversity in the community invaded by S. trilobata

Summary

Introduction

Biodiversity is important in the functional provision and stability of ecosystems [1, 2]. The expansion of urbanization, and the conversion of forest lands for agricultural development lead to increasing losses of native species [7, 8] and result in the establishment and spreading of alien inhabitants in these communities [5]. These non-indigenous inhabitants can change the structure and diversity of the plant community by suppressing subordinate species [9]. Exotic invasions continue to crowd out native plant species and homogenize biota around the world [11, 12], with the consequences of decreasing global biodiversity [13] and impairing ecosystem functions [10, 14]

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