Consequences of Repeated Defoliation on Belowground Bud Banks of Carex brevicuspis (Cyperaceae) in the Dongting Lake Wetlands, China

Xin-Sheng Chen,Yong-Hong Xie,Zhi-Yong Hou,Zheng-Miao Deng,Chao Wu,Feng Li

doi:10.3389/fpls.2016.01119

Xin-Sheng Chen, Yong-Hong Xie + Show 4 more

Open Access

https://doi.org/10.3389/fpls.2016.01119

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Abstract

Despite the predominant role of bud banks in the regeneration of clonal macrophyte populations, few studies have examined the way in which clonal macrophytes adjust the demographic features of bud banks to regulate population dynamics in response to defoliation in wetlands. We investigated the density and composition of bud banks under repeated defoliation in the wetland sedge Carex brevicuspis C. B. Clarke in the Dongting Lake wetlands, China. The density and biomass of rhizome buds and shoots did not decrease significantly in response to repeated defoliation over two consecutive years. The composition of bud banks, which consisted of long and short rhizome buds, also did not change significantly in response to repeated defoliation. Nevertheless, the ramet height and the shoot, root, and rhizome mass of C. brevicuspis declined significantly under repeated defoliation. Our findings suggest that bud banks are a conservative reproductive strategy that enables C. brevicuspis to tolerate a certain amount of defoliation. The maintenance of large bud banks after repeated defoliation may enable C. brevicuspis populations to regenerate and persist in disturbed habitats. However, bud bank density of C. brevicuspis might decline in the long term because the amount of carbon stored in rhizome buds and plants is reduced by frequent defoliation.

Highlights

Defoliation by herbivores or mowing is a common disturbance in ecosystems dominated by perennials, such as grasslands and wetlands (Zhao et al, 2008; Terer et al, 2012)
We investigated the temporal dynamics of the shoot population and bud banks by sampling the aboveground shoot populations and the belowground bud banks for three defoliation frequencies over two consecutive years in the Dongting Lake wetlands
Repeated defoliation did not change the seasonal dynamics of the bud bank density of C. brevicuspis, which peaked in January and was lowest in March for all treatments

Summary

Introduction

Defoliation by herbivores or mowing is a common disturbance in ecosystems dominated by perennials, such as grasslands and wetlands (Zhao et al, 2008; Terer et al, 2012) In these ecosystems, clonal plants reproduce predominantly from a belowground population of meristems, the “bud bank” (Harper, 1977; Benson et al, 2004; Benson and Hartnett, 2006; Sosnová et al, 2010; Ott and Hartnett, 2012; Deng et al, 2015). The population dynamics of clonal species in response to defoliation may be determined by the demographic features of bud banks, such as the number of buds available for tiller recruitment and their emergence rate (Tuomi et al, 1994; Huhat et al, 2000; Lehtilä, 2000; Dalgleish and Hartnett, 2009). The effect of defoliation on bud bank demography may vary among seasons

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