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1. Global response patterns of plant photosynthesis to nitrogen addition: A meta‐analysis

   https://doi.org/10.1111/gcb.15071  

   Liang, Xingyun; Zhang, Tong; Lu, Xiankai; Ellsworth, David S; BassiriRad, Hormoz; You, Chengming; Wang, Dong; He, Pengcheng; Deng, Qi; Liu, Hui; et al (June 2020, Global Change Biology)

   Abstract A mechanistic understanding of plant photosynthetic response is needed to reliably predict changes in terrestrial carbon (C) gain under conditions of chronically elevated atmospheric nitrogen (N) deposition. Here, using 2,683 observations from 240 journal articles, we conducted a global meta‐analysis to reveal effects of N addition on 14 photosynthesis‐related traits and affecting moderators. We found that across 320 terrestrial plant species, leaf N was enhanced comparably on mass basis (N_mass, +18.4%) and area basis (N_area, +14.3%), with no changes in specific leaf area or leaf mass per area. Total leaf area (TLA) was increased significantly, as indicated by the increases in total leaf biomass (+46.5%), leaf area per plant (+29.7%), and leaf area index (LAI, +24.4%). To a lesser extent than for TLA, N addition significantly enhanced leaf photosynthetic rate per area (A_area, +12.6%), stomatal conductance (g_s, +7.5%), and transpiration rate (E, +10.5%). The responses ofA_areawere positively related with that ofg_s, with no changes in instantaneous water‐use efficiency and only slight increases in long‐term water‐use efficiency (+2.5%) inferred from¹³C composition. The responses of traits depended on biological, experimental, and environmental moderators. As experimental duration and N load increased, the responses of LAI andA_areadiminished while that ofEincreased significantly. The observed patterns of increases in both TLA andEindicate that N deposition will increase the amount of water used by plants. Taken together, N deposition will enhance gross photosynthetic C gain of the terrestrial plants while increasing their water loss to the atmosphere, but the effects on C gain might diminish over time and that on plant water use would be amplified if N deposition persists. 

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2. The ontogenetic dimension of plant functional ecology

   https://doi.org/10.1111/1365-2435.14464  

   Barton, Kasey E. (November 2023, Functional Ecology)

   Abstract Plant functional strategies change considerably as plants develop, driven by intraindividual variability in anatomical, morphological, physiological and architectural traits.Developmental trait variation arises through the complex interplay among genetically regulated phase change (i.e. ontogeny), increases in plant age and size, and phenotypic plasticity to changing environmental conditions. Although spatial drivers of intraspecific trait variation have received extensive research attention, developmentally driven intraspecific trait variation is largely overlooked, despite widespread occurrence.Ontogenetic trait variation is genetically regulated, leads to dramatic changes in plant phenotypes and evolves in response to predictable changes in environmental conditions as plants develop.Evidence has accumulated to support a general shift from fast to slow relative growth rates and from shade to sun leaves as plants develop from the highly competitive but shady juvenile niche to the stressful adult niche in the systems studied to date.Nonetheless, there are major gaps in our knowledge due to examination of only a few environmental factors selecting for the evolution of ontogenetic trajectories, variability in how ontogeny is assigned, biogeographic sampling biases on trees in temperate biomes, dependencies on a few broadly sampled leaf morphological traits and a lack of longitudinal studies that track ontogeny within individuals. Filling these gaps will enhance our understanding of plant functional ecology and provide a framework for predicting the effects of global change threats that target specific ontogenetic stages. Read the freePlain Language Summaryfor this article on the Journal blog. 

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3. The sensitivity of reconstructed carbon dioxide concentrations to stomatal preparation methods using a leaf gas exchange model

   https://doi.org/10.1002/aps3.11629  

   Machesky, Michael D; Sheldon, Nathan D; Hren, Michael T; Smith, Selena Y (January 2025, Applications in Plant Sciences)

   Abstract PremiseMechanistic models using stomatal traits and leaf carbon isotope ratios to reconstruct atmospheric carbon dioxide (CO₂) concentrations (c_a) are important to understand the Phanerozoic paleoclimate. However, methods for preparing leaf cuticles to measure stomatal traits have not been standardized. MethodsThree people measured the stomatal density and index, guard cell length, guard cell pair width, and pore length of leaves from the sameGinkgo biloba,Quercus alba, andZingiber miogaleaves growing at known CO₂levels using four preparation methods: fluorescence on cleared leaves, nail polish, dental putty on fresh leaves, and dental putty on dried leaves. ResultsThere are significant differences between trait measurements from each method. Modeledc_acalculations are less sensitive to method than individual traits; however, the choice of assumed carbon isotope fractionation also impacted the accuracy of the results. DiscussionWe show that there is not a significant difference betweenc_aestimates made using any of the four methods. Further study is needed on the fractionation due to carboxylation of ribulose bisphosphate (RuBP) in individual plant species before use as a paleo‐CO₂barometer and to refine estimates based upon widely applied taxa (e.g.,Ginkgo). Finally, we recommend that morphological measurements be made by multiple observers to reduce the effect of individual observational biases. 

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4. High hydraulic safety, water use efficiency and a conservative resource‐use strategy in woody species of high‐altitude environments: A global study

   https://doi.org/10.1111/ppl.70064  

   Waseem, Muhammad; Kuzyakov, Yakov; Carriquí, Marc; Scoffoni, Christine; Zhang, Kaiping; Hasan, Md Mahadi; Yao, Guang‐Qian; He, Lei; Shao, Jing; Mei, Fengyuan; et al (March 2025, Physiologia Plantarum)

   Abstract Understanding the impact of altitude on leaf hydraulic, gas exchange, and economic traits is crucial for comprehending vegetation properties and ecosystem functioning. This knowledge also helps to elucidate species' functional strategies regarding their vulnerability or resilience to global change effects in alpine environments. Here, we conducted a global study of dataset encompassing leaf hydraulic, gas exchange, and economic traits for 3391 woody species. The results showed that high‐altitude species possessed greater hydraulic safety (K_leafP₅₀), higher water use efficiency (WUE_i) and conservative resource use strategy such as higher leaf mass per area, longer leaf lifespan, lower area‐based leaf nitrogen and phosphorus contents, and lower rates of photosynthesis and dark respiration. Conversely, species at lower altitudes exhibited lower hydraulic safety (K_leafP₅₀), lower water use efficiency (WUE_i) and an acquisitive resource use strategy. These global patterns of leaf traits in relation to altitude reveal the strategies that alpine plants employ for hydraulic safety, water use efficiency, and resource, which have important implications for predicting forest productivity and acclimation to rapid climate change. 

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5. ‘Slow‐Fast’ Plant Trait Spectra Are Associated With Ecological Niches Across Global Climatic Gradients

   https://doi.org/10.1111/geb.70115  

   Chen, Yuheng; Hautier, Yann; Kowalchuk, George A; Barry, Kathryn E (September 2025, Global Ecology and Biogeography)

   ABSTRACT AimGlobal climate change is compressing species' realised niches and further threatening their distributions. Species traits, especially the trait spectra synthesised from traits, are one way in which species can match changes in their environment. Hence, integrating trait spectra and niches will help us understand how species adapt to their environment under global change. LocationGlobal. Time PeriodPresent. Major Taxa StudiedAngiosperms. MethodWe collected root traits from 158 angiosperm species and leaf traits from 512 angiosperm species from a global trait database to construct the leaf and root trait ‘slow‐fast’ spectrum based on resource acquisition strategy, as well as the collaboration spectrum related to root mycorrhizal colonisation. After rebuilding their phylogenetic relationships and defining species' environmental niches based on 213,979 occurrences of these species, we examined the relationship between these trait spectra and environmental niches along global climatic patterns. ResultPlants with ‘slow’ leaf traits were generally associated with narrow niche breadths and marginal niche positions, especially in high precipitation areas. The relationship between the ‘slow‐fast’ spectrum in root traits and ‘marginal‐central’ niche position reversed with decreasing precipitation. However, the relationships between leaf traits and niche variables were significant for woody species but not for herbaceous species. Main ConclusionOur research expands the plant trait spectra in macroecology applications. The root and leaf ‘slow‐fast’ trait spectra of angiosperms are driven by both macroclimate and long‐term evolutionary pressure. Understanding how these traits relate to the niche of species helps to predict how that species is likely to adapt to environmental change, which can enhance the predictive ability of niche theory for plant environmental adaptability. 

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