Understory Floristic Diversity in Poplar Plantations in the Dongting Lake Wetlands, China
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WETLANDS CONSERVATION
Understory Floristic Diversity in Poplar Plantations in the Dongting Lake Wetlands, China Bo Ren 1 & Yonghong Xie 2,3 & Youzhi Li 1,2,3 Received: 25 September 2019 / Accepted: 26 November 2019 # Society of Wetland Scientists 2019
Abstract Large-scale poplar plantations have evoked great concern over their adverse effects on floristic diversity in understory vegetation. The aim of this study was to investigate the effects of tree density on the composition of understory vegetation in poplar (Populus deltoides) plantations in the Dongting Lake wetlands, China. Stand characteristics and soil properties had significant effects on understory plant distribution. Stand density was positively correlated with number of species, Shannon diversity index, and proportions of mesophytes and partial-shade plants but was negatively correlated with the proportions of hygrophytes and heliophytes. Understory light availability was negatively correlated with number of species, Shannon diversity index, and the proportions of mesophytes and partial-shade plants and was positively correlated with the proportions of hygrophytes and heliophytes. Soil water content was negatively correlated with species richness and the proportion of mesophytes and was positively correlated with the proportions of hygrophytes and heliophytes. Compared to low-density stands, high-density stands had a higher number of species and higher proportion of annual/biennial plants, mesophytes, and xerophytes and had lower proportions of perennial plants and hygrophytes during the one-year monitoring period. Therefore, poplar plantations should be managed at lower densities in the Dongting Lake wetlands to conserve the understory flora. Keywords Light availability . Soil water . Species composition . Species richness . Stand density . Populus deltoides
Introduction Poplars are important forest trees and are extensively planted in farmlands and wetlands worldwide (Zerbe 2003; Soo et al. 2009; Fortier et al. 2011). Large-scale poplar plantations have evoked widespread concern because of their adverse effects on floristic diversity (Lust et al. 2001; Weih et al. 2003). To date, few studies have assessed floristic diversity in poplar plantations, and contradicting findings have been reported (Weih et al. 2003; Fortier et al. 2011). For example, a previous study has shown that poplar stands in a short-rotation culture
* Youzhi Li [email protected] 1
Hunan Provincial Key Laboratory of Rural Ecosystem Health in Dongting Lake Area, College of Resources and Environment, Hunan Agricultural University, Changsha, China
2
Key Laboratory of Agro-Ecological Processes in Subtropical Region, The Chinese Academy of Sciences, Changsha, China
3
Dongting Lake Station for Wetland Ecosystem Research, Institute of Subtropical Agriculture, Changsha, China
decreased long-term floristic diversity compared to that in an adjacent old-growth forest (Halpern and Spiess 1995). In contrast, another study has shown that small-scale poplar stands had a ‘catalytic effe
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