Nitrogen allocation and partitioning in invasive and native Eupatorium species.
There is a trade-off between nitrogen (N) allocation to photosynthesis and to defence. Invasive species may reduce N allocation to defence because of the absence of natural enemies. Thus, I hypothesised that invasive species may allocate a higher fraction of total leaf N to photosynthesis and have higher light-saturated photosynthetic rate (P(max)) and photosynthetic N-use efficiency (PNUE) than closely related native species. To test these hypotheses, invasive Eupatorium adenophorum and native E. chinense and E. heterophyllum were compared in a limestone shrub. Unlike expectation, the invader did not allocate a higher fraction of leaf N to photosynthesis than the natives. However, it was more efficient in photosynthetic N partitioning than the natives. It partitioned a higher fraction of the photosynthetic N to carboxylation and showed higher use efficiency of the photosynthetic N, while the natives partitioned a higher fraction of the photosynthetic N to light-harvesting components. Total leaf N content was not significantly different among the three studied invasive and native species. For the invader, the higher fraction of leaf N allocated to carboxylation resulted in the higher N content in carboxylation and in both carboxylation and bioenergetics, which led to higher P(max), and therefore to higher PNUE, water-use efficiency, respiration efficiency and apparent quantum yield. These physiological advantages of the invader and its higher leaf area ratio may contribute to its invasiveness.
Feng
Yu-Long
YL
Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, 88 Xuefu Road, Kunming, Yunnan Province 650223, China. fyl@xtbg.ac.cn
D036603:Ageratina / Q000378:metabolism; D002264:Carboxylic Acids / Q000378:metabolism; D004734:Energy Metabolism; D036602:Eupatorium / Q000378:metabolism*; D008954:Models, Biological; D009584:Nitrogen / Q000378:metabolism*; D010788:Photosynthesis; D013045:Species Specificity
D002264:Carboxylic Acids; D009584:Nitrogen