Cronin Greg, Lodge David M
Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556, USA.
Oecologia. 2003 Sep;137(1):32-41. doi: 10.1007/s00442-003-1315-3. Epub 2003 Jun 19.
Phenotypic responses of Potamogeton amplifolius and Nuphar advena to different light (7% and 35% of surface irradiance) and nutrient environments were assessed with field manipulation experiments. Higher light and nutrient availability enhanced the growth of P. amplifolius by 154% and 255%, respectively. Additionally, biomass was allocated differently depending on the resource: high light availability resulted in a higher root/shoot ratio, whereas high nutrient availability resulted in a lower root/shoot ratio. Low light availability and high nutrient availability increased the nitrogen content of leaf tissue by 53% and 40% respectively, resulting in a 37% and 31% decrease in the C/N ratio. Root nitrogen content was also increased by low light and high nutrient availability, by 50% (P=0.0807) and 77% respectively, resulting in a 20% and 40% decrease in root C/N ratio. Leaf phenolics were significantly increased 72% by high light and 31% by high nutrient availability, but root phenolic concentrations were not altered significantly. None of these changes in tissue constituents resulted in altered palatability to crayfish. N. advena was killed by the same high nutrient treatment that stimulated growth in P. amplifolius, preventing assessment of phenotypic responses to nutrient availability. However, high light availability increased overall growth by 24%, but this was mainly due to increased growth of the rhizome (increased 100%), resulting in a higher root/shoot ratio. High light tended to increase the production of floating leaves (P=0.09) and significantly decreased the production of submersed leaves. High light availability decreased the nitrogen content by 15% and 25% and increased the phenolic concentration by 88% and 255% in floating and submersed leaves, respectively. These differences in leaf traits did not result in detectable differences in damage by herbivores.
通过田间操控实验评估了宽叶眼子菜（Potamogeton amplifolius）和萍蓬草（Nuphar advena）对不同光照（表面辐照度的7%和35%）和养分环境的表型响应。较高的光照和养分有效性分别使宽叶眼子菜的生长提高了154%和255%。此外，生物量分配因资源不同而有所差异：高光照条件下根/茎比更高，而高养分条件下根/茎比更低。低光照和高养分有效性分别使叶片组织的氮含量增加了53%和40%，导致碳氮比分别降低了37%和31%。低光照和高养分有效性也使根氮含量分别增加了50%（P = 0.0807）和77%，导致根碳氮比分别降低了20%和40%。高光照使叶片酚类物质显著增加72%，高养分有效性使其增加31%，但根酚类物质浓度没有显著变化。这些组织成分的变化均未导致小龙虾适口性的改变。与刺激宽叶眼子菜生长的相同高养分处理杀死了萍蓬草，从而无法评估其对养分有效性的表型响应。然而，高光照使整体生长提高了24%，但这主要是由于根状茎生长增加（增加了100%），导致根/茎比更高。高光照倾向于增加浮叶的产量（P = 0.09）并显著降低沉水叶的产量。高光照使浮叶和沉水叶的氮含量分别降低了15%和25%，酚类物质浓度分别增加了88%和255%。这些叶片性状的差异并未导致食草动物造成的损害有可检测到的差异。
