Artemisia halodendron Litters Have Strong Negative Allelopathic Effects on Earlier Successional Plants in a Semi-Arid Sandy Dune Region in China.

Yongqing Luo,Mai-He Li,Yue Yang,Xueyong Zhao,Zhong Du,Yuqiang Li,Haibo Jiang,Zhiqiang Yan

doi:10.3389/fpls.2020.00961

Abstract

Artemisia halodendron Turcz. ex Besser occurs following the appearance of a pioneer species, Agriophyllum squarrosum (L.) Moq., with the former replacing the latter during the naturally vegetation succession in sandy dune regions in China. A previous study revealed that the foliage litter of A. halodendron had strong negative allelopathic effects on germination of the soil seed bank and on the seedling growth. However, whether this allelopathic effect varies with litter types and with the identity of plant species has not yet been studied. We, therefore, carried out a seed germination experiment to determine the allelopathic effects of three ltter types of A. halodendron (roots, foliage, and stems) on seed germination of six plant species that progressively occur along a successional gradient in the semi-arid grasslands in the Horqin Sandy Land of northeastern China. In line with our expectation, we found that the early-successional species rather than the late-successional species were negatively affected by A. halodendron and that the allelopathic effects on seed germination increase with increasing concentration of litter extracts, irrespective of litter types. Our study evidenced the negative allelopathic effects of A. halodendron on the species replacement and on the community composition during dune stabilization in the Horqin Sandy Land. Further studies are needed to better understand the successional process and thus to promote the vegetation restoration in that sandy dune region as A. halodendron itself disappeared also during the process.

Highlights

Plant litter can affect the structure and composition of plant communities directly through its influence on the emergence and early growth of seedlings (Sayer, 2006; Li K. et al, 2016)
The present study indicated that the seed germination of the early- (A. squarrosum) and early late-successional species (C. macrocarpum) was significantly suppressed by the extracts of A. halodendron litters (Figures 3A, B and 4A, B)
4A, B), whereas the late-successional species (e.g. A. scoparia, C. acuminatum) were rarely affected by such effects (Figures 3C, E and 4C, E). These findings suggest that the allelopathy of A. halodendron seems to accelerate plant succession during the early stage of plant restoration in the Horqin Sandy Land

Summary

Introduction

Plant litter can affect the structure and composition of plant communities directly through its influence on the emergence and early growth of seedlings (Sayer, 2006; Li K. et al, 2016). The influence of plant litter on plant establishment can be negative or positive, and these influences differ among species, litter types, and litter quantity (Hovstad and Ohlson, 2008). Allelopathy is defined as the stimulatory or inhibitory effects of one plant upon another, including interactions with microorganisms (Rice, 1984). The foliage litter of Artemisia halodendron can affect the establishment of other species by allelopathy in degraded sandy grassland (Luo et al, 2017). Root litter of Eucalyptus urophylla in a subtropical forest ecosystem significantly inhibited the germination and height growth of Schima superba, Michelia macclurei, and Elaeocarpus sylvestris due to allelopathy (Zhang and Fu, 2009)

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