Bringing together leaf trait data spanning 2,548 species and 175 sites we describe, for the first time at global scale, a universal spectrum of leaf economics consisting of key chemical, structural and physiological properties. The spectrum runs from quick to slow return on investments of nutrients and dry mass in leaves, and operates largely independently of growth form, plant functional type or biome. Categories along the spectrum would, in general, describe leaf economic variation at the global scale better than plant functional types, because functional types overlap substantially in their leaf traits. Overall, modulation of leaf traits and trait relationships by climate is surprisingly modest, although some striking and significant patterns can be seen. Reliable quantification of the leaf economics spectrum and its interaction with climate will prove valuable for modelling nutrient fluxes and vegetation boundaries under changing land-use and climate.

/pdf/the-worldwide-leaf-economics-spectrum-1uikdmil76.pdf

The worldwide leaf economics spectrum

Plant functional traits are the features (morphological, physiological, phenological) that represent ecological strategies and determine how plants respond to environmental factors, affect other trophic levels and influence ecosystem properties. Variation in plant functional traits, and trait syndromes, has proven useful for tackling many important ecological questions at a range of scales, giving rise to a demand for standardised ways to measure ecologically meaningful plant traits. This line of research has been among the most fruitful avenues for understanding ecological and evolutionary patterns and processes. It also has the potential both to build a predictive set of local, regional and global relationships between plants and environment and to quantify a wide range of natural and human-driven processes, including changes in biodiversity, the impacts of species invasions, alterations in biogeochemical processes and vegetation–atmosphere interactions. The importance of these topics dictates the urgent need for more and better data, and increases the value of standardised protocols for quantifying trait variation of different species, in particular for traits with power to predict plant- and ecosystem-level processes, and for traits that can be measured relatively easily. Updated and expanded from the widely used previous version, this handbook retains the focus on clearly presented, widely applicable, step-by-step recipes, with a minimum of text on theory, and not only includes updated methods for the traits previously covered, but also introduces many new protocols for further traits. This new handbook has a better balance between whole-plant traits, leaf traits, root and stem traits and regenerative traits, and puts particular emphasis on traits important for predicting species’ effects on key ecosystem properties. We hope this new handbook becomes a standard companion in local and global efforts to learn about the responses and impacts of different plant species with respect to environmental changes in the present, past and future.

/pdf/new-handbook-for-standardised-measurement-of-plant-5aljxhhg5y.pdf

New handbook for standardised measurement of plant functional traits worldwide

An important aim of plant ecology is to identify leading dimensions of ecological variation among species and to understand the basis for them. Dimensions that can readily be measured would be especially useful, because they might offer a path towards improved worldwide synthesis across the thousands of field experiments and ecophysiological studies that use just a few species each. Four dimensions are reviewed here. The leaf mass per area-leaf lifespan (LMA-LL) dimension expresses slow turnover of plant parts (at high LMA and long LL), long nutrient residence times, and slow response to favorable growth conditions. The seed mass-seed output (SM-SO) dimension is an important predictor of dispersal to establishment opportunities (seed output) and of establishment success in the face of hazards (seed mass). The LMA-LL and SM-SO dimensions are each underpinned by a single, comprehensible tradeoff, and their consequences are fairly well understood. The leaf size-twig size (LS-TS) spectrum has obvious consequences for the texture of canopies, but the costs and benefits of large versus small leaf and twig size are poorly understood. The height dimension has universally been seen as ecologically important and included in ecological strategy schemes. Nevertheless, height includes several tradeoffs and adaptive elements, which ideally should be treated separately. Each of these four dimensions varies at the scales of climate zones and of site types within landscapes. This variation can be interpreted as adaptation to the physical environment. Each dimension also varies widely among coexisting species. Most likely this within-site variation arises because the ecological opportunities for each species depend strongly on which other species are present, in other words, because the set of species at a site is a stable mixture of strategies.

/pdf/plant-ecological-strategies-some-leading-dimensions-of-xkw2sqjd4d.pdf

Plant Ecological Strategies: Some Leading Dimensions of Variation Between Species

Global climate change impacts can already be tracked in many physical and biological systems; in particular, terrestrial ecosystems provide a consistent picture of observed changes. One of the preferred indicators is phenology, the science of natural recurring events, as their recorded dates provide a high-temporal resolution of ongoing changes. Thus, numerous analyses have demonstrated an earlier onset of spring events for mid and higher latitudes and a lengthening of the growing season. However, published single-site or single-species studies are particularly open to suspicion of being biased towards predominantly reporting climate change-induced impacts. No comprehensive study or meta-analysis has so far examined the possible lack of evidence for changes or shifts at sites where no temperature change is observed. We used an enormous systematic phenological network data set of more than 125 000 observational series of 542 plant and 19 animal species in 21 European countries (1971–2000). Our results showed that 78% of all leafing, flowering and fruiting records advanced (30% significantly) and only 3% were significantly delayed, whereas the signal of leaf colouring/fall is ambiguous. We conclude that previously published results of phenological changes were not biased by reporting or publication predisposition: the average advance of spring/summer was 2.5 days decade � 1 in Europe. Our analysis of 254 mean national time series undoubtedly demonstrates that species’ phenology is responsive to temperature of the preceding

/pdf/european-phenological-response-to-climate-change-matches-the-3dr30qvjfp.pdf

European phenological response to climate change matches the warming pattern

Here, we analysed a wide range of literature data on the leaf dry mass per unit area (LMA). In nature, LMA varies more than 100-fold among species. Part of this variation (c. 35%) can be ascribed to differences between functional groups, with evergreen species having the highest LMA, but most of the variation is within groups or biomes. When grown in the same controlled environment, leaf succulents and woody evergreen, perennial or slow-growing species have inherently high LMA. Within most of the functional groups studied, high-LMA species show higher leaf tissue densities. However, differences between evergreen and deciduous species result from larger volumes per area (thickness). Response curves constructed from experiments under controlled conditions showed that LMA varied strongly with light, temperature and submergence, moderately with CO2 concentration and nutrient and water stress, and marginally under most other conditions. Functional groups differed in the plasticity of LMA to these gradients. The physiological regulation is still unclear, but the consequences of variation in LMA and the suite of traits interconnected with it are strong. This trait complex is an important factor determining the fitness of species in their environment and affects various ecosystem processes.

/pdf/causes-and-consequences-of-variation-in-leaf-mass-per-area-4q0s917bw1.pdf

Causes and consequences of variation in leaf mass per area (LMA): a meta-analysis.

This paper demonstrates a new analysis of photon flux partitioning among species and an evaluation of the efficiency of photon flux capturing in terms of biomass investment. For that purpose, distributions of aboveground biomass, leaf area, and photon flux density (PPFD) were determined with the stratified harvest method in a stand of a tall herbaceous community on a floating fen at the time of peak standing crop. The stand contained 11 species and the photon flux absorbed by each species in the stand was esti- mated. Three tall dominant species absorbed 75% of the incident PPFD, while eight short subordinate species absorbed 2.5%. Tall species in the canopy received higher PPFD av- eraged over leaf area (4)area). However, the PPFD absorbed per unit aboveground biomass (4)mass) of the tall species was not higher than that of the subordinate species. (Fmass is a product of the leaf area ratio (LAR, the ratio of leaf area to aboveground biomass) and

Canopy Structure and Photon Flux Partitioning Among Species in a Herbaceous Plant Community

1 We compared allometric growth patterns, canopy structure and light interception for individual shoots of different species in a tall-grass meadow.



2 The vertical distributions of above-ground biomass, leaf area, height and leaf angles were measured, both early and late in the season, for individual shoots of Miscanthus sinensis (the dominant species), Lespedeza bicolor, Lysimachia clethroides, Astilbe thunbergii and Potentilla freyniana. A canopy model was developed to calculate light absorption by individual shoots. Light absorption per unit mass (Φmass) was used to quantify the efficiency with which plants utilized biomass to capture light.



3 The leaf mass ratio (LMR), average specific leaf area (SLA) and therefore the leaf area ratio (LAR) decreased with shoot height and light availability. Light absorption per unit leaf area (Φarea) increased with shoot height, and this increase was observed to be much stronger at greater than at smaller shoot heights.



4 In the taller species (Miscanthus and Lespedeza) Φmass (the product of LAR and Φarea) increased, while in the shortest species (Potentilla) it decreased with shoot height. Clones of Miscanthus and Lespedeza may thus increase total light capture by allocating shoot biomass among fewer taller shoots, and a clone of Potentilla by producing a larger number of shorter shoots.



5 Shoots of the shorter species were equally efficient in capturing light (i.e. they had similar Φmass) early in the season, but less efficient later in the season than shoots of the taller species. Shorter species appear to be able to use the earlier part of the season for efficient light capture, while shoots of taller species gain an advantage from their height later in the season.



6 This study shows how different above-ground growth patterns of the species in a tall-grass meadow allow them to use different positions in vertical space and different periods of the season to absorb light efficiently. This is a clear example of niche separation and helps to explain the coexistence of these species.

Interspecific differences in above-ground growth patterns result in spatial and temporal partitioning of light among species in a tall-grass meadow

1. Photosynthetic characteristics of an annual herb, Chenopodium album, and an evergreen tree, Quercus myrsinaefolia, were compared to clarify causes of the difference in photosynthetic nitrogen-use efficiency (photosynthetic capacity per unit nitrogen) between leaves of herbaceous and evergreen species.



2. When leaves with the same nitrogen content on an area basis were compared, photosynthetic capacity of C. album was twice as high as that of Q. myrsinaefolia. Gas-exchange measurements showed higher intercellular CO2 concentration in C. album. Biochemical analyses indicated larger allocation of nitrogen into ribulose-1,5-bisphosphate carboxylase, a key enzyme of photosynthesis, and higher specific activity of ribulose-1,5-bisphosphate carboxylase in C. album. However, these differences were not large.



3. Compositional deviation of 13C in leaves of the two species suggested that the drop of CO2 level between the intercellular space and the chloroplast was slightly larger in Q. myrsinaefolia when compared between the leaves with the same photosynthetic capacity.



4. It is concluded that the difference in photosynthetic nitrogen-use efficiency between C. album and Q. myrsinaefolia is not caused by a sole factor that is markedly different between the two species but by several factors each of which is slightly disadvantageous to Q. myrsinaefolia compared with C. album.

https://besjournals.onlinelibrary.wiley.com/doi/pdf/10.1046/j.1365-2435.1998.00272.x

Photosynthetic nitrogen‐use efficiency in leaves of woody and herbaceous species

Changes in the temperature dependence of the photosynthetic rate depending on growth temperature were investigated for a temperate evergreen tree, Quercus myrsinaefolia. Plants were grown at 250 μmol quanta m–2 s–1 under two temperature conditions, 15 and 30 °C. The optimal temperature that maximizes the light-saturated rate of photosynthesis at 350 μL L–1 CO2 was found to be 20–25 and 30–35 °C for leaves grown at 15 and 30 °C, respectively. We focused on two processes, carboxylation and regeneration of ribulose-1,5-bisphosphate (RuBP), which potentially limit photosynthetic rates. Because the former process is known to limit photosynthesis at lower CO2 concentrations while the latter limits it at higher CO2 concentrations, we determined the temperature dependence of the photosynthetic rate at 200 and 1000 μL L–1 CO2 under saturated light. It was revealed that the temperature dependence of both processes varied depending on the growth temperature. Using a biochemical model, we estimated the capacity of the two processes at various temperatures under ambient CO2 concentration. It was suggested that, in leaves grown at low temperature (15 °C), the photosynthetic rate was limited solely by RuBP carboxylation under any temperature. On the other hand, it was suggested that, in leaves grown at high temperature (30 °C), the photosynthetic rate was limited by RuBP regeneration below 22 °C, but limited by RuBP carboxylation above 22 °C. We concluded that: (1) the changes in the temperature dependence of carboxylation and regeneration of RuBP and (2) the changes in the balance of these two processes altered the temperature dependence of the photosynthetic rate.

Balancing carboxylation and regeneration of ribulose‐1,5‐ bisphosphate in leaf photosynthesis: temperature acclimation of an evergreen tree, Quercus myrsinaefolia

We studied the effects of CO2 elevation on leaf and canopy photosynthesis and optimal leaf area index (LAI) for stands of the annual species Abutilon theophrasti and Ambrosia artemisiifolia. Leaf photosynthesis was modeled as a function of photosyn- thetic photon flux density (PPFD) and nitrogen content per unit leaf area (NL). There was a curvilinear relationship between the light-saturated rates of leaf photosynthesis (Pmax) and NL. CO2 elevation significantly increased Pmax as a function of NL in both species. Dark respiration (Rd) was linearly correlated with NL. CO2 elevation slightly but significantly increased Rd in Abutilon, while it had no significant effect on Rd in Ambrosia. The initial slope of a light-response curve was determined from quantum yield (4gabs) multiplied by leaf absorptance and then calibrated against NL. Daily canopy photosynthesis, calculated by integration of leaf photosynthesis with the actual distribution of leaf area, leaf N, and PPFD within a canopy, showed fairly good agreement with the canopy photosynthesis estimated from growth analysis. CO2 elevation increased canopy photosynthesis by 30- 50%. Based on the leaf photosynthesis model for Abutilon, we calculated daily canopy photosynthesis for a given LAI and N availability, in which N was assumed to be distributed optimally within a leaf canopy to maximize daily canopy photosynthesis. An optimal LAI to maximize daily canopy photosynthesis was obtained for each level of N availability and this optimum increased with increasing N availability. Contrary to the often predicted increase in LAI with CO2 elevation, the optimum LAI did not increase at high CO2 when N availability was limited. Two factors were suggested to be involved in counteracting the increase in LAI in a high-CO2 world. One is the higher 4abs of plants grown in elevated C02, which makes leaves in the canopy more N limited, favors higher NL and thus lowers optimal LAI. The other is the higher Rd in elevated C02, which leads to higher light compensation points, and lowers optimal LAI.

https://www.jstor.org/stable/info/2265896

Tadaki Hirose

Papers

Canopy Structure and Photon Flux Partitioning Among Species in a Herbaceous Plant Community

Interspecific differences in above-ground growth patterns result in spatial and temporal partitioning of light among species in a tall-grass meadow

Photosynthetic nitrogen‐use efficiency in leaves of woody and herbaceous species

Balancing carboxylation and regeneration of ribulose‐1,5‐ bisphosphate in leaf photosynthesis: temperature acclimation of an evergreen tree, Quercus myrsinaefolia

Co2 elevation, canopy photosynthesis, and optimal leaf area index