Abstract
Geographic patterns in leaf stoichiometry reflect plant adaptations to environments. Leaf stoichiometry variations along environmental gradients have been extensively studied among terrestrial plants, but little has been known about intraspecific leaf stoichiometry, especially for wetland plants. Here we analyzed the dataset of leaf N and P of a cosmopolitan wetland species, Phragmites australis, and environmental (geographic, climate and soil) variables from literature and field investigation in natural wetlands distributed in three climatic regions (subtropical, temperate and highland) across China. We found no clear geographic patterns in leaf nutrients of P. australis across China, except for leaf N:P ratio increasing with altitude. Leaf N and N:P decreased with mean annual temperature (MAT), and leaf N and P were closely related to soil pH, C:N ratio and available P. Redundancy analysis showed that climate and soil variables explained 62.1% of total variation in leaf N, P and N:P. Furthermore, leaf N in temperate region and leaf P in subtropical region increased with soil available P, while leaf N:P in subtropical region decreased with soil pH. These patterns in P. australis different from terrestrial plants might imply that changes in climate and soil properties can exert divergent effects on wetland and terrestrial ecosystems.
Highlights
Are strongly correlated with nutrient availability in the soil
Leaf N and N:P ratio of P. australis were highest in highlands, which may be due to the much lower temperature and higher soil N in this climatic region (Supplementary Fig. S1)
Low temperature tended to aid the physiological acclimation of N and P, which was predicted by the Temperature-Dependent Physiology Hypothesis[11,15,30]
Summary
Are strongly correlated with nutrient availability in the soil. The shift from N to P limitation in soils toward lower latitude makes tissue N:P ratio decreased with increasing latitude[17,18,19]. Different climatic regions cover different parts of environmental gradients, we hypothesized that leaf N, P and N:P ratio of a wetland species at different climatic regions are affected by different environmental factors To test these hypotheses, we used the data set on leaf N and P of the wetland plant Phragmites australis and environmental variables from published studies and our field investigation in natural wetlands across the species range in China. It distributed widely in different climatic regions from tropical to temperate regions in China as well as in the world[27] Owing to both phenotypic plasticity and genetic variability, the variation in morphological and chemical traits of P. australis is considerable[27,28,29]. These characteristics made P. australis a suitable plant for studying the intraspecific variation in leaf N and P
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