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| 1 | Global leaf nitrogen and phosphorus stoichiometry and their scaling exponent显示文摘Leaf nitrogen(N) and phosphorus(P) concentrations constrain photosynthetic and metabolic processes,growth and the productivity of plants. Their stoichiometry and scaling relationships regulate the allocation of N and P from subcellular to organism, and even ecosystem levels, and are crucial to the modelling of plant growth and nutrient cycles in terrestrial ecosystems. Prior work has revealed a general biogeographic pattern of leaf N and P stoichiometric relationships and shown that leaf N scales roughly as two-thirds the power of P. However, determining whether and how leaf N and P stoichiometries, especially their scaling exponents, change with functional groups and environmental conditions requires further verification. In this study, we compiled a global data set and documented the global leaf N and P concentrations and the N:P ratios by functional group, climate zone and continent. The global overall mean leaf N and P concentrations were 18.9 mg g^(-1) and 1.2 mg g^(-1), respectively, with significantly higher concentrations in herbaceous than woody plants(21.72 mg g^(-1) vs. 18.22 mg g^(-1) for N; and 1.64 mg g^(-1) vs. 1.10 mg g^(-1) for P). Both leaf N and P showed higher concentrations at high latitudes than low latitudes. Among six continents, Europe had the highest N and P concentrations(20.79 and 1.54 mg g^(-1)) and Oceania had the smallest values(10.01 and 0.46 mg g^(-1)). These numerical values may be used as a basis for the comparison of other individual studies. Further, we found that the scaling exponent varied significantly across different functional groups,latitudinal zones, ecoregions and sites. The exponents of herbaceous and woody plants were 0.659 and0.705, respectively, with significant latitudinal patterns decreasing from tropical to temperate to boreal zones. At sites with a sample size ≥10, the values fluctuated from 0.366 to 1.928, with an average of 0.841.Several factors including the intrinsic attributes of different life forms, P-related growth rates and relative nutrient availability of soils likely account for the inconstant exponents of leaf N vs. P scaling relationships. | Di Tian Zhengbing Yan Karl J.Niklas Wenxuan Han Jens Kattge Peter B.Reich Yongkai Luo Yahan Chen Zhiyao Tang Huifeng Hu Ian J.Wright Bernhard Schmid Jingyun Fang | 2018 | National Science Review2018,5,5: | 24 |
| 2 | Multi-scale phylogenetic structure in coastal dune plant communities across the globe显示文摘Aims Studies integrating phylogenetic history and large-scale community assembly are few,and many questions remain unanswered.Here,we use a global coastal dune plant data set to uncover the important factors in community assembly across scales from the local filtering processes to the global long-term diversification and dispersal dynamics.Coastal dune plant communities occur worldwide under a wide range of climatic and geologic conditions as well as in all biogeographic regions.However,global patterns in the phylogenetic composition of coastal dune plant communities have not previously been studied.Methods The data set comprised vegetation data from 18463 plots in New Zealand,South Africa,South America,North America and Europe.The phylogenetic tree comprised 2241 plant species from 149 families.We calculated phylogenetic clustering(Net Relatedness Index,NRI,and Nearest Taxon Index,NTI)of regional dune floras to estimate the amount of in situ diversification relative to the global dune species pool and evaluated the relative importance of land and climate barriers for these diversification patterns by geographic analyses of phylogenetic similarity.We then tested whether dune plant communities exhibit similar patterns of phylogenetic structure within regions.Finally,we calculated NRI for local communities relative to the regional species pool and tested for an association with functional traits(plant height and seed mass)thought to vary along sea–inland gradients.Important Findings Regional species pools were phylogenetically clustered relative to the global pool,indicating regional diversification.NTI showed stronger clustering than NRI pointing to the importance of especially recent diversifications within regions.The species pools grouped phylogenetically into two clusters on either side of the tropics suggesting greater dispersal rates within hemispheres than between hemispheres.Local NRI plot values confirmed that most communities were also phylogenetically clustered within regions.NRI values decreased with increasing plant height and seed mass,indicating greater phylogenetic clustering in communities with short maximum height and good dispersers prone to wind and tidal disturbance as well as salt spray,consistent with environmental filtering along sea–inland gradients.Height and seed mass both showed significant phylogenetic signal,and NRI tended to correlate negatively with both at the plot level.Low NRI plots tended to represent coastal scrub and forest,whereas high NRI plots tended to represent herb-dominated vegetation.We conclude that regional diversification processes play a role in dune plant community assembly,with convergence in local phylogenetic community structure and local variation in community structure probably reflecting consistent coastal-inland gradients.Our study contributes to a better understanding of the globally distributed dynamic coastal ecosystems and the structuring factors working on dune plant communities across spatial scales and regions. | Ane Kirstine Brunbjerg Jeannine Cavender-Bares Wolf L.Eiserhardt Rasmus Ejrnæs Lonnie W.Aarssen Hannah L.Buckley Estelle Forey Florian Jansen Jens Kattge Cynthia Lane Roy A.Lubke Angela T.Moles Ana Laura Monserrat Robert K.Peet Julissa Roncal Louise Wootton Jens-Christian Svenning | 2014 | Journal of Plant Ecology2014,7,2: | 9 |
| 3 | Family-level leaf nitrogen and phosphorus stoichiometry of global terrestrial plants显示文摘Leaf nitrogen(N) and phosphorus(P) concentrations are critical for photosynthesis, growth, reproduction and other ecological processes of plants. Previous studies on large-scale biogeographic patterns of leaf N and P stoichiometric relationships were mostly conducted using data pooled across taxa, while family/genus-level analyses are rarely reported. Here, we examined global patterns of family-specific leaf N and P stoichiometry using a global data set of 12,716 paired leaf N and P records which includes 204 families, 1,305 genera, and 3,420 species. After determining the minimum size of samples(i.e., 35 records), we analyzed leaf N and P concentrations, N:P ratios and N^P scaling relationships of plants for 62 families with 11,440 records. The numeric values of leaf N and P stoichiometry varied significantly across families and showed diverse trends along gradients of mean annual temperature(MAT) and mean annual precipitation(MAP). The leaf N and P concentrations and N:P ratios of 62 families ranged from 6.11 to 30.30 mg g–1, 0.27 to 2.17 mg g–1, and 10.20 to 35.40, respectively. Approximately 1/3–1/2 of the families(22–35 of 62) showed a decrease in leaf N and P concentrations and N:P ratios with increasing MAT or MAP, while the remainder either did not show a significant trend or presented the opposite pattern. Family-specific leaf N^P scaling exponents did not converge to a certain empirical value, with a range of 0.307–0.991 for 54 out of 62 families which indicated a significant N^P scaling relationship. Our results for the first time revealed large variation in the family-level leaf N and P stoichiometry of global terrestrial plants and that the stoichiometric relationships for at least one-third of the families were not consistent with the global trends reported previously. The numeric values of the family-specific leaf N and P stoichiometry documented in the current study provide critical synthetic parameters for biogeographic modeling and for further studies on the physiological and ecological mechanisms underlying the nutrient use strategies of plants from different phylogenetic taxa. | Di Tian Zhengbing Yan Suhui Ma Yuehong Ding Yongkai Luo Yahan Chen Enzai Du Wenxuan Han Emoke Dalma Kovacs Haihua Shen Huifeng Hu Jens Kattge Bernhard Schmid Jingyun Fang | 2019 | Science China(Life Sciences)2019,62,8: | 7 |