Zaret Max, Kinkel Linda, Borer Elizabeth T, Seabloom Eric W
Department of Ecology, Evolution and Behavior, University of Minnesota, Saint Paul, Minnesota, USA.
Department of Plant Pathology, University of Minnesota, Saint Paul, Minnesota, USA.
Ecology. 2024 May;105(5):e4290. doi: 10.1002/ecy.4290. Epub 2024 Apr 3.
Plants face trade-offs between allocating resources to growth, while also defending against herbivores or pathogens. Species differences along defense trade-off axes may promote coexistence and maintain diversity. However, few studies of plant communities have simultaneously compared defense trade-offs against an array of herbivores and pathogens for which defense investment may differ, and even fewer have been conducted in the complex natural communities in which these interactions unfold. We tested predictions about the role of defense trade-offs with competition and growth in diversity maintenance by tracking plant species abundance in a field experiment that removed individual consumer groups (mammals, arthropods, fungi) and added nutrients. Consistent with a growth-defense trade-off, plant species that increased in mass in response to nutrient addition also increased when consumers were removed. This growth-defense trade-off occurred for all consumer groups studied. Nutrient addition reduced plant species richness, which is consistent with trade-off theory. Removing foliar fungi increased plant diversity via increased species evenness, whereas removal of other consumer groups had little effect on diversity, counter to expectations. Thus, while growth-defense trade-offs are general across consumer groups, this trade-off observed in wild plant communities does not necessarily support plant diversity maintenance.
植物在将资源分配用于生长的同时，还要抵御食草动物或病原体，这面临着权衡取舍。沿着防御权衡轴的物种差异可能促进共存并维持多样性。然而，很少有关于植物群落的研究同时比较针对一系列防御投资可能不同的食草动物和病原体的防御权衡，在这些相互作用发生的复杂自然群落中进行的研究甚至更少。我们通过在一项田间实验中追踪植物物种丰度来测试关于防御权衡在多样性维持中与竞争和生长的作用的预测，该实验去除了单个消费者群体（哺乳动物、节肢动物、真菌）并添加了养分。与生长 - 防御权衡一致，对添加养分有质量增加反应的植物物种在去除消费者时也增加了。这种生长 - 防御权衡在所研究的所有消费者群体中都出现了。添加养分降低了植物物种丰富度，这与权衡理论一致。去除叶部真菌通过增加物种均匀度提高了植物多样性，而去除其他消费者群体对多样性影响不大，这与预期相反。因此，虽然生长 - 防御权衡在各消费者群体中普遍存在，但在野生植物群落中观察到的这种权衡不一定支持植物多样性的维持。
