Wuhan Botanical Institute/Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, Hubei, China.
Plant Biol (Stuttg). 2010 May 1;12(3):445-52. doi: 10.1111/j.1438-8677.2009.00247.x.
Facilitation, both by inter- and intra-specific neighbours, is known to be an important process in structuring plant communities. However, only a small number of experiments have been reported on facilitation in plant invasions, especially between invasive con-specific individuals. Here, we focus on how con-specific neighbours of the invasive alien plant alligator weed affect the tolerance of alligator weed to herbivory by the introduced biological control agent, Agasicles hygrophila. We conducted greenhouse and garden experiments in which invasive plant density and herbivory intensity (artificial clipping and real herbivory) were manipulated. In the greenhouse experiment, artificial clipping significantly reduced plant biomass when plants were grown individually, but when con-specific neighbours were present in the same pot, biomass was not significantly different from control plants. Similarly, when compared to control plants, plants that were subjected to herbivory by A. hygrophila produced more biomass when grown with two con-specific neighbours than when grown alone. Real herbivory also resulted in an increased number of vegetative buds, and again when two con-specific neighbours were present this effect was increased (a 55.3% increase in buds when there was no neighbour, but a 111.6% increase in buds when two con-specific neighbours were present). In the garden experiment, in which plants were grown at high density (6 plants per pot), alligator weed fully recovered from defoliation caused by insects at levels from 20-30% to 100%. Our results indicate that the con-specific association may increase the compensatory ability to cope with intense damage in this invasive plant.
促进作用，无论是种间还是种内的邻居，都被认为是植物群落结构的一个重要过程。然而，只有少数实验报告了植物入侵中的促进作用，特别是在入侵同种个体之间。在这里，我们关注的是入侵外来植物鳄鱼草的同种邻居如何影响鳄鱼草对引入的生物防治剂 Agasicles hygrophila 的抗虫性。我们进行了温室和花园实验，其中操纵了入侵植物密度和草食强度（人工修剪和真实草食）。在温室实验中，当植物单独生长时，人工修剪显著降低了植物生物量，但当同种邻居存在于同一盆中时，生物量与对照植物没有显著差异。同样，与对照植物相比，当受到 A. hygrophila 的草食时，与两个同种邻居一起生长的植物产生的生物量比单独生长时多。真正的草食也导致了更多的营养芽的产生，而且当有两个同种邻居存在时，这种效果会增加（当没有邻居时芽的数量增加了 55.3%，而当有两个同种邻居时芽的数量增加了 111.6%）。在花园实验中，在高密度（每盆 6 株）下种植植物时，鳄鱼草从昆虫造成的 20-30%到 100%的落叶中完全恢复。我们的结果表明，同种关联可能会增加这种入侵植物应对强烈伤害的补偿能力。
