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Leaf respiration in the light (R light) is crucial for understanding the net CO2 exchange of individual plants and entire ecosystems. However, R light is poorly quantified and rarely discussed in the context of the leaf economic spectrum (LES), especially among woody species differing in plant functional types (PFTs) (e.g. evergreen vs. deciduous species). To address this gap in our knowledge, R light, respiration in the dark (R dark), light-saturated photosynthetic rates (A sat), leaf dry mass per unit area (LMA), leaf nitrogen (N) and phosphorus (P) concentrations, and maximum carboxylation (V cmax) and electron transport rates (J max) of 54 representative subtropical woody evergreen and deciduous species were measured. With the exception of LMA, the parameters quantified in this study were significantly higher in deciduous species than in evergreen species. The degree of light inhibition did not significantly differ between evergreen (52%) and deciduous (50%) species. R light was significantly correlated with LES traits such as A sat, R dark, LMA, N and P. The R light vs. R dark and N relationships shared common slopes between evergreen and deciduous species, but significantly differed in their y-intercepts, in which the rates of R light were slower or faster for any given R dark or N in deciduous species, respectively. A model for R light based on three traits (i.e. R dark, LMA and P) had an explanatory power of 84.9%. These results show that there is a link between R light and the LES, and highlight that PFTs is an important factor in affecting R light and the relationships of R light with R dark and N. Thus, this study provides information that can improve the next generation of terrestrial biosphere models (TBMs). [ABSTRACT FROM AUTHOR]

Evergreen and deciduous species coexist in the subtropical forests in southeastern China. It has been suggested that phosphorus (P) is the main limiting nutrient in subtropical forests, and that evergreen and deciduous species adopt different carbon capture strategies to deal with this limitation. However, these hypotheses have not been examined empirically to a sufficient degree. In order to fill this knowledge gap, we measured leaf photosynthetic and respiration rates, and nutrient traits related to P-, nitrogen (N)- and carbon (C)-use efficiencies and resorption using 75 woody species (44 evergreen and 31 deciduous species) sampled in a subtropical forest. The photosynthetic N-use efficiency (PNUE), respiration rate per unit N and P (R d,N and R d,P, respectively) of the deciduous species were all significantly higher than those of evergreen species, but not in the case of photosynthetic P-use efficiency. These results indicate that, for any given leaf P, evergreen species manifest higher carbon-use efficiency (CUE) than deciduous species, a speculation that is empirically confirmed. In addition, no significant differences were observed between deciduous and evergreen species for nitrogen resorption efficiency, phosphorus resorption efficiency or N:P ratios. These results indicate that evergreen species coexist with deciduous species and maintain dominance in P-limited subtropical forests by maintaining CUE. Our results also indicate that it is important to compare the PNUE of deciduous species with evergreen species in other biomes. These observations provide insights into modeling community dynamics in subtropical forests, particularly in light of future climate change. [ABSTRACT FROM AUTHOR]

Carbon (C), nitrogen (N), and phosphorus (P) stoichiometry and their allometric relationships in soil and plants are hot topics that attract a lot of attention, while those rocks that form soils are often neglected. Weathering is a common geological phenomenon that may significantly influence the nutrient composition and release of nutrients from rock and its inherent soils. This study presents C, N, and P concentrations data as well as microscope petrological photographs of fresh and weathered sandstones from Longhushan World Geopark in SE China, in an attempt to investigate C, N, and P stoichiometry of rocks before and after weathering and discuss the driving mechanisms. The results show that weathering significantly decreased rock C, C/N, and C/P concentrations, slightly decreased N and N/P concentrations, and slightly increased P concentration. Microscope observations show that fresh sandstones contain calcite, apatite, microplagioclase, and organic matter, while weathered sandstones feature apatite and organic matter. The flexible allometric relationships and mineral changes before and after rock weathering indicate that chemical mechanisms, such as dissolution of carbonate and hydration of microplagioclase, have changed the existence form of C, N, P and, thus, significantly influence rock C, N, and P stoichiometry. This stoichiometry feature can be in turn used to reflect the regulation effect of rock weathering. [ABSTRACT FROM AUTHOR]

The whole‐plant economics spectrum (PES) refers to the trade‐offs among the many plant functional traits that are commonly used as indicators of major adaptive strategies, thereby providing insights into plant distributions, ecosystem processes and evolution. However, there are few studies of what may be called the whole‐PES that integrates bark, wood and leaf functional traits for different leaf types and growth habits (evergreen vs. deciduous species).To address this gap in our knowledge, 6 bark traits, 7 wood traits (including mechanical support and nutrient transport characteristics) and 12 leaf traits (including chemical, structural and physiological characteristics) of 59 representative subtropical woody species were examined using principal component analysis (PCA) to determine PES strategies.The economics spectra of bark (BES), wood (WES) and leaves (LES), and the entire PES indicated that major traits represent resource acquisition strategies and conservation strategies clustering on the opposite ends of the PCA axis. A significant correlation was observed among the 25 functional traits. The data indicated that N and P nutrient levels were at the hub of BES, WES, LES and PES interrelationships. Evergreen and deciduous species had different WES and LES, and thus PES resource acquisition strategies. With the exception of the BES, evergreen species clustered on the conservative side, whereas deciduous species clustered on the acquisitive side.Synthesis. The PES presented here informs our understanding of whole‐plant responses to environmental differences, particularly regarding the role of N and P traits at the whole‐plant level. It also reveals and further supports the notion that evergreen and deciduous species, respectively, manifest conservative and acquisitive strategies, further informing our understanding of species biodiversity maintenance. [ABSTRACT FROM AUTHOR]