光照限制和入侵克隆植物三裂叶蟛蜞菊的凋落物抑制其幼苗更新。
Light limitation and litter of an invasive clonal plant, Wedelia trilobata, inhibit its seedling recruitment.
作者信息
Qi Shan-Shan, Dai Zhi-Cong, Miao Shi-Li, Zhai De-Li, Si Chun-Can, Huang Ping, Wang Rui-Ping, Du Dao-Lin
机构信息
Institute of Environment and Ecology, School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang 212013, China.
West Palm Beach, FL 33413, USA.
出版信息
Ann Bot. 2014 Aug;114(2):425-33. doi: 10.1093/aob/mcu075. Epub 2014 May 13.
BACKGROUND AND AIMS
Invasive clonal plants have two reproduction patterns, namely sexual and vegetative propagation. However, seedling recruitment of invasive clonal plants can decline as the invasion process proceeds. For example, although the invasive clonal Wedelia trilobata (Asteraceae) produces numerous seeds, few seedlings emerge under its dense population canopy in the field. In this study it is hypothesized that light limitation and the presence of a thick layer of its own litter may be the primary factors causing the failure of seedling recruitment for this invasive weed in the field.
METHODS
A field survey was conducted to determine the allocation of resources to sexual reproduction and seedling recruitment in W. trilobata. Seed germination was also determined in the field. Effects of light and W. trilobata leaf extracts on seed germination and seedling growth were tested in the laboratory.
KEY RESULTS
Wedelia trilobata blooms profusely and produces copious viable seeds in the field. However, seedlings of W. trilobata were not detected under mother ramets and few emerged seedlings were found in the bare ground near to populations. In laboratory experiments, low light significantly inhibited seed germination. Leaf extracts also decreased seed germination and inhibited seedling growth, and significant interactions were found between low light and leaf extracts on seed germination. However, seeds were found to germinate in an invaded field after removal of the W. trilobata plant canopy.
CONCLUSIONS
The results indicate that lack of light and the presence of its own litter might be two major factors responsible for the low numbers of W. trilobata seedlings found in the field. New populations will establish from seeds once the limiting factors are eliminated, and seeds can be the agents of long-distance dispersal; therefore, prevention of seed production remains an important component in controlling the spread of this invasive clonal plant.
背景与目的
入侵性克隆植物有两种繁殖方式，即有性繁殖和营养繁殖。然而，随着入侵过程的推进，入侵性克隆植物的幼苗补充可能会减少。例如，尽管入侵性克隆植物三裂叶蟛蜞菊（菊科）能产生大量种子，但在野外其密集的植株冠层下很少有幼苗出现。本研究假设光照限制和自身厚厚的枯枝落叶层的存在可能是导致这种入侵杂草在野外幼苗补充失败的主要因素。
方法
进行了一项野外调查，以确定三裂叶蟛蜞菊有性繁殖和幼苗补充的资源分配情况。还在野外测定了种子萌发情况。在实验室中测试了光照和三裂叶蟛蜞菊叶片提取物对种子萌发和幼苗生长的影响。
主要结果
三裂叶蟛蜞菊在野外大量开花并产生大量有活力的种子。然而，在母株分株下未检测到三裂叶蟛蜞菊的幼苗，且在种群附近的裸地中发现的出苗幼苗也很少。在实验室实验中，低光照显著抑制种子萌发。叶片提取物也降低了种子萌发并抑制了幼苗生长，并且在低光照和叶片提取物对种子萌发的影响之间发现了显著的相互作用。然而，在去除三裂叶蟛蜞菊植株冠层后，在入侵田地中发现种子能够萌发。
结论
结果表明，光照不足和自身枯枝落叶层的存在可能是导致野外三裂叶蟛蜞菊幼苗数量少的两个主要因素。一旦限制因素被消除，新的种群将从种子建立，并且种子可以成为远距离传播的媒介；因此，防止种子生产仍然是控制这种入侵性克隆植物传播的重要组成部分。
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