Floating plants are widespread in aquatic ecosystems. Most floating plants are clonal and their clones can be easily fragmented as a result of natural events or human activities. Such clonal fragmentation may decrease the growth and thus the competitive ability of floating plants. We tested these hypotheses with the widespread floating, clonal plant Salvinia natans . We simulated disturbance-mediated fragmentation of S. natans clones at two levels (low or high) by cutting clones initially consisting of six connected ramets into two fragments with three connected ramets each or six fragments with one ramet each), with no fragmentation as the control. These fragmented or intact clones were grown under two nutrient levels (low or high) in the presence or absence of the floating plant S. polyrhiza . High nutrient availability significantly increased the biomass and ramet number of S. natans , and the presence of S. polyrhiza reduced them. Furthermore, the negative effect of competition of S. polyrhiza on S. natans was greater under high than under low nutrient availability. Clonal fragmentation of S. natans significantly decreased its growth, but did not affect its competitive response or effect. Thus, nutrient availability can affect competition between S. natans and S. polyrhiza , but clonal fragmentation cannot. Our results suggest that clonal fragmentation and decreasing nutrient availability can decrease the spread of some clonal floating plants in aquatic ecosystems and that increasing disturbance to fragment clones and reducing nutrient load in water could be efficient at controlling the spread of some floating plants.

中文翻译：

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克隆破碎和养分有效性对漂浮植物丹参竞争能力的影响

漂浮植物广泛存在于水生生态系统中。大多数漂浮植物是无性系的，它们的无性系很容易因自然事件或人类活动而破碎。这种克隆分裂可能会降低漂浮植物的生长，从而降低其竞争能力。我们用广泛漂浮的无性系植物丹参（Salvinia natans）检验了这些假设。我们通过将最初由六个连接的分株组成的克隆切割成两个片段，每个片段具有三个连接的分枝或六个片段，每个片段具有一个分枝，在两个水平（低或高）模拟干扰介导的 S. natans 克隆的断裂，没有碎片作为控制。在漂浮植物多根草存在或不存在的情况下，这些片段化或完整克隆在两种营养水平（低或高）下生长。高养分可利用性显着增加了 S. natans 的生物量和分株数，而 S. polyrhiza 的存在减少了它们。此外，S. polyrhiza 竞争对 S. natans 的负面影响在高养分供应下比在低养分供应下更大。S. natans 的克隆分裂显着降低了其生长，但不影响其竞争反应或效果。因此，养分可利用性可以影响 S. natans 和 S. polyrhiza 之间的竞争，但克隆碎片不能。我们的研究结果表明，克隆分裂和养分可用性的降低可以减少一些无性系漂浮植物在水生生态系统中的传播，增加对分裂克隆的干扰和减少水中的养分负荷可以有效地控制一些漂浮植物的传播。