Specific Leaf Area Values Research Articles

Responses of Leaf Expansion, Plant Transpiration and Leaf Senescence of Different Soybean (Glycine max. (L.) Merr.) Genotypes to Soil Water Deficit

ABSTRACTThe responses of eco‐physiological processes such as leaf expansion, plant transpiration and senescence to soil water deficit have been reported to be genotype‐dependent in different crops. To study such responses in soybean (Glycine max. (L.) Merr.), a 2‐year (2017 and 2021) outdoor pot experiment was carried out on the Heliaphen automated phenotyping platform at INRAE in Toulouse (France). Six soybean cultivars (Sultana‐MG 000, ES Pallador‐MG I, Isidor‐MG I, Santana‐MG I/II, Blancas‐MG II and Ecudor‐MG II) belonging to four maturity groups (MG) commonly grown in Europe were subjected to progressive soil water deficit from the reproductive stage R1 for 17 and 23 days in 2017 and 2021, respectively. The fraction of transpirable soil water (FTSW) was used as an indicator of soil water deficit. Non‐linear regression was used to calculate FTSWt, that is, the FTSW threshold for which the rate of the eco‐physiological process in stressed plants starts to diverge from a reference value. According to FTSWt, the three eco‐physiological processes showed significant differences in sensitivity to water deficit: leaf expansion exhibits the highest sensitivity and the widest range (FTSWt: 0.44–0.93), followed by plant transpiration (FTSWt: 0.17–0.56), with leaf senescence showing the narrowest range (FTSWt: 0.05–0.16). Among six cultivars, regarding leaf expansion, Cvs Santana (FTSWt = 0.48 in 2017; FTSWt = 0.44 in 2021), Blancas (FTSWt = 0.51 in 2017; FTSWt = 0.48 in 2021) and Ecudor (FTSWt = 0.46 in 2017; FTSWt = 0.52 in 2021) in late MGs (I/II to II) exhibited higher tolerance to soil drying. Conversely, the cv. Sultana in the earliest MG (000) showed the highest sensitivity (FTSWt = 0.91 in 2017; FTSWt = 0.93 in 2021) to water deficit. However, concerning the FTSWt values for plant transpiration (0.17–0.56 in 2017; 0.19–0.31 in 2021) and senescence (0.05–0.16 in 2017; 0.06–0.16 in 2021), their range did not demonstrate a correlated trend with the MG. In addition, a negative linear correlation was observed between values of FTSWt of normalised leaf expansion at the whole‐plant level (NLE) and specific leaf area (SLA) measured on irrigated plants for both years. This suggests that genotypes with high values of SLA could be associated with higher tolerance of leaf expansion to soil water deficit. Such a non‐destructive phenotyping method under outdoor conditions could bring new information to variety testing process and provide paths for integrating genotypic variability into crop growth models used for simulating soybean eco‐physiological responses to water deficit across the plant, field and even regional scales.

Specific leaf area and its within-individual variation in understory evergreen and deciduous woody species in New Zealand

Specific leaf area (SLA) plays a critical role in carbon assimilation and nutrient cycling. While leaf habit (deciduous vs. evergreen) has often been recognized as a reliable predictor of SLA—with deciduous species typically having higher mean SLA values due to lower concentration of structural components compared to evergreens—high variation in SLA among evergreen species suggests further investigation of variation for species with this leaf habit could improve predictions of SLA effects on community and ecosystem processes. Furthermore, the presence of leaves of different ages in evergreen plants, emerging over multiple years, could amplify the within-individual variation in SLA, which remains underexplored. Here we report variations of SLA measured from c. 2000 leaves collected from 36 individuals across 19 woody species in an understory environment in New Zealand (NZ). We found that while most deciduous species, predominantly non-native, clustered towards higher SLA values, evergreen species presented a wide SLA spectrum. Moreover, we found that while being deciduous, having a smaller leaf size, and younger leaves, collected from lateral branches, correlated with elevated SLA values, the leaf habit did not primarily drive the within-individual SLA variation. Instead, smaller leaf size emerged as a significant predictor of within-individual SLA variation. The branch-order effect on SLA underscores a methodological consideration: accurate estimation of total leaf area in evergreen trees requires representative sampling across all branch orders. Our study also highlights the need for integrating leaf traits such as leaf size and branch order into functional trait analyses. Further research is vital to understand the underlying mechanisms of these trait variations and their impacts on ecosystem functioning.

Plasticity in biomass allocation underlies tolerance to leaf damage in native and non-native populations of Datura stramonium

An introduction to a novel habitat represents a challenge to plants because they likely would face new interactions and possibly different physical context. When plant populations arrive to a new region free from herbivores, we can expect an evolutionary change in their defense level, although this may be contingent on the type of defense, resistance or tolerance, and cost of defense. Here, we addressed questions on the evolution of tolerance to damage in non-native Spanish populations of Datura stramonium by means of two comparative greenhouse experiments. We found differences in seed production, specific leaf area, and biomass allocation to stems and roots between ranges. Compared to the Mexican native populations of this species, non-native populations produced less seeds despite damage and allocate more biomass to roots and less to stems, and had higher specific leaf area values. Plasticity to leaf damage was similar between populations and no difference in tolerance to damage between native and non-native populations was detected. Costs for tolerance were detected in both regions. Two plasticity traits of leaves were associated with tolerance and were similar between regions. These results suggest that tolerance remains beneficial to plants in the non-native region despite it incurs in fitness costs and that damage by herbivores is low in the non-native region. The study of the underlying traits of tolerance can improve our understanding on the evolution of tolerance in novel environments, free from plants’ specialist herbivores.

Leaf functional traits of Daphniphyllum macropodum across different altitudes in Mao’er Mountain in Southern China

Investigating functional traits among mountain species with differing altitude requirements is integral to effective conservation practices. Our study aims to investigate the structural and chemical characteristics of Daphniphyllum macropodum leaves at three altitudes (1100 m, 1300 m, and 1500 m) across southern China to provide insight into changes in leaf functional traits (LFT) as well as plant adaptations in response to changing environmental conditions. Leaf structural characteristics include leaf thickness (LT), leaf area (LA), specific leaf area (SLA), and leaf tissue density (LD), respectively, while chemical properties include carbon-nitrogen-phosphorus (C:N:P) contents and ratios, such as C/N, C/P, and N/P. Our findings demonstrated the significant effect of altitude on both structural (LT, SLA, LD) and chemical aspects (N, C/N, N/P) of LFT. In particular, leaves at 1100 and 1300 m differed greatly, with 1300 m having lower SLA values than 1100 m. Observable trends included an initial increase followed by a decline as the altitude rose. Notable among them were the LT, LD, N, and N/P values at both locations. Traits at 1300 m were significantly higher than at 1100 m; SLA and C/N values displayed an inverse trend, with their lowest values occurring at 1300 m. Furthermore, this research demonstrated various degrees of variation among LFT, with structural traits exhibiting greater fluctuation than chemical traits. Robust correlations were observed among certain traits, such as LT, LD, and SLA. Furthermore, the interdependency relationships between N and C/N, as well as P and C/P, demonstrated interconnectedness. Redundancy analysis indicated that soil factors, specifically P content, exerted the strongest impact on LFT. At 1100 m, D. macropodum employed acquisition strategies; however, at 1300 m, conservation strategies emerged, showing a shift from acquisition strategies at lower altitudes to conservative strategies at higher ones.

Far-red radiation management for lettuce growth: Physiological and morphological features leading to energy optimization in vertical farming

Recently, far-red wavelengths (FR, 700–750 nm) have been largely investigated in indoor cultivation systems due to their morphological effects on plants (e.g., leaf expansion and stem elongation), resulting also in increasing yield. This work investigated the effect of substituting part of the red (R) and blue (B) radiation with far-red radiation, while keeping constant the photon flux density, in the light spectrum for lettuce grown in a vertical farm. Lettuce (Lactuca sativa var. Canasta) plants were transplanted and grown in an ebb-and-flow system for 29 days. During the cycle, plants were subjected to five different light treatments: a control treatment consisting of an optimized R and B spectrum (ratio of 3; RB3) with a photosynthetic photon flux density of 200 µmol m−2 s−1, and four treatments in which R and B were partially replaced by 10, 30, 50 and 70 µmol m−2 s−1 of FR light, resulting in an increasing FR fraction. Biomass production and most of the morphological parameters were affected from 15 days after transplanting (DAT), while stomatal conductance from 22 DAT. Leaf greenness and specific leaf area values were influenced by the FR radiation starting from 8 DAT. At 29 DAT, substitution of an amount of R and B photons equal to 30 (RB3–30) or 50 (RB3–50) µmol m−2 s−1 with the same amount of FR radiation resulted in increased leaf biomass in both fresh (+49 and +47%, respectively) and dry weight (+45 and +42%, respectively). With RB3–30, the increase was due to leaf area expansion (+103%), whereas stomatal conductance (gs) and quantum efficiency of photosystem II (ΦPSII) did not change compared with the spectrum with only R and B. With RB3–50, gs and ΦPSII decreased compared with RB3 (-27 and -6%, respectively), but the greater biomass accumulation was supported by the greater leaf expansion (+119 %). The adoption of RB3–30 and RB3–50 also promoted light use efficiency (+45 and +42 %, respectively), lighting energy use efficiency (+48 and +53 %, respectively) and therefore the overall energy performance of the system. The adoption of RB3–30 and RB3–50 is a valid strategy to increase yield for lettuce production, but further studies, also in relation to blue radiation intensity, are needed to avoid the negative effect on leaf pigmentation.

The Effect of Irrigation Water Quality and Growing Medium on Growth Parameters of Chokeberry

This study aimed to determine the effect of irrigation water quality and growing medium differences on the growth parameters of the chokeberry plant. The effects of control (0.65 dS m-1), 2 dS m-1, 4 dS m-1, 8 dS m-1, and 10 dS m-1 electrical conductivity irrigation water and 2 different growing medium (peat and soil) were evaluated on plant growth. For this purpose, specific leaf area (SLA), leaf area ratio (LAR), leaf weight ratio (LWR), stem weight ratio (SWR), root weight ratio (RWR), net assimilation rate (NAR), relative growth rate (RGR), and leaf thickness (LT) parameters were evaluated. Differences were observed in growth parameters depending on irrigation water salinity and growing medium. The SLA value varied between 26.47 (control) and 3.07 cm2 day-1 (10 dS m-1) in soil medium and between 25.07 (control) and 2.88 cm2 day-1 (10 dS m-1) in peat medium. The values of LAR ranged between 127.98-12.65 cm2 day-1 in soil and 134.14-61.33 cm2 day-1 in peat, and LWR between 0.25-0.03 g g-1 (soil) and 0.43-0.05 g g-1 (peat). The SWR value varied between 0.41-0.18 g g-1 in soil and 1.22-0.29 g g-1 in peat. The RWR value ranged between 0.63-0.37 g g-1 in the soil medium and 1.62-0.31 g g-1 in the peat medium. NAR and RGR are the most potent parameters used to evaluate plant growth and to express growth and development. NAR and RGR parameters reached the highest value in soil medium in 2 dS m-1 application, while in peat medium in control application.

Influence of Bradyrhizobium japonicum on the growth parameters and formation of the assimilation apparatus in E-gene isogenic lines of soybean

The study investigated the impact of the interaction between soybean and rhizobia on the assimilation apparatus functioning and biomass accumulation in different soybean lines with varying photoperiod sensitivity. Nearly isogenic lines (NILs) of soybean were used, with genes E1, E2, and E3 in different allelic states: Clark (e1E2E3), L80-5879 (E1e2e3), L63-3117 (e1e2E3), and L71-920 (e1e2e3). The experimental group for each line was treated with Bradyrhizobium japonicum 634b. Plants were grown under natural long-day conditions (16 hours). Growth indicators of the studied lines, such as relative growth rate (RGR), net assimilation rate (NAR), leaf area ratio (LAR), and specific leaf area (SLA), were analyzed, as well as the content of chlorophylls A and B in the V3 and V5 developmental stages. The results demonstrate that the influence of rhizobia on the functioning of the assimilation apparatus and biomass accumulation depends on the soybean line genotype. In the study, RGR, which characterizes the biomass accumulation rate, has similar trends to those observed with NAR, characterizing the assimilation apparatus's functioning. However, each line showed its own tendencies. For instance, in the short-day variety Clark, under bacterial influence, the value of RGR and NAR decreased. Additionally, LAR and SLA values indicated a reduction in the total photosynthetic surface area and leaf dry matter. Bacterial inoculation did not significantly affect the content of photosynthetic pigments in Clark leaves. Another short-day line, L80-5879, showed no significant impact of bacterial inoculation on biomass accumulation. However, soybean interaction with Bradyrhizobium japonicum 634b led to a decrease in leaf surface area and dry matter content. Probably, bacterial inoculation supported assimilation processes by increasing auxiliary chlorophyll b in photosystem I. A general trend of significant RGR reduction in neutral-day soybean lines, L63-3117 and L71-920, was identified under bacterial influence. The interaction with rhizobia differently affected LAR and SLA values, indicating distinct adaptive mechanisms to the interactions. In conditions of almost zero plant biomass accumulation, Bradyrhizobium japonicum 634b caused a decrease in the total photosynthetic surface area and chlorophyll a and b content in the L63-3117 line. In L71-920, bacterial inoculation had no effect on the total photosynthetic surface area, while leaf dry matter and photosynthetic pigment content decreased. The obtained results demonstrate that interaction with rhizobia can influence the functioning of the assimilation apparatus in soybeans with varying photoperiod sensitivity that is determined by genotype. It is important in improving soybean productivity and its application in agricultural practices.

The impact of environmental factors on traits of Hedera helix L. vegetative shoots

Hedera helix L. is an evergreen vine native to Europe. Nowadays, it is commonly recognized as an expansive species, posing danger to biodiversity of natural ecosystems. Obtaining the relationships between morphological variability, productive parameters of vegetative individuals, and variations in environmental factors (on the example of the Kórnik Arboretum) is important for understanding the successful adaptation and dispersion of H. helix. Thus, the issue of our studies was to discover the link between environmental factors and morphometric measurements of H. helix. We collected data on leaf length, leaf width, leaf petiole length, plant stem length, and the number of leaves per stem. We assessed values of ecological plasticity and correlation between the studied parameters. The results indicated the tolerance of ivy to wide variation in edaphic conditions. The limiting environmental factors for growth of the studied subpopulations were soil moisture and light intensity. We found large variability of leaf morphometric parameters and shoot length. Close correlation links were detected between leaf length/leaf width, leaf length/leaf petiole length, and leaf width/leaf petiole length. The length of the average leaf and the length of leaf petiole were the most variable parameters under different values of light intensity. Weak relationships were found between light intensity at the soil surface and plant stem length/the number of leaves per shoot. A high level of index of morphological integration of H. helix individuals and a close relationship between the quality index/subpopulation compositions were established in this study. A direct relationship between light intensity and specific leaf area values was established. The value of specific leaf area decreased linearly with increasing light intensity at the soil surface.

Variations and driving factors of leaf functional traits in the dominant desert plant species along an environmental gradient in the drylands of China

Leaf functional traits (LFTs) of desert plants are responsive, adaptable and highly plastic to their environment. However, the macroscale variation in LFTs and driving factors underlying this variation remain unclear, especially for desert plants. Here, we measured eight LFTs, including leaf carbon concentration (LCC), leaf nitrogen concentration (LNC), leaf phosphorus concentration (LPC), specific leaf area (SLA), leaf dry matter content (LDMC), leaf mass per area (LMA), leaf thickness (LTH) and leaf tissue density (LTD) across 114 sites along environmental gradient in the drylands of China and in Guazhou Common Garden and evaluated the effect of environment and phylogeny on the LFTs. We noted that for all species, the mean values of LCC, LNC, LPC, SLA, LDMC, LMA, LTH and LTD were 384.62 mg g−1, 19.91 mg g−1, 1.12 mg g−1, 79.62 cm2 g−1, 0.74 g g−1, 237.39 g m−2, 0.38 mm and 0.91 g cm−3, respectively. LFTs exhibited significant geographical variations and the LNC, LMA and LTH in the plants of Guazhou Common Garden were significantly higher than the field sites in the drylands of China. LDMC and LTD of plants in Guazhou Common Garden were, however, considerably lower than those in the drylands of China. LCC, LPC, LTH and LTD differed significantly among different plant lifeforms, while LNC, SLA, LDMC and LMA didn't show significant variations. We found that the environmental variables explained higher spatial variations (3.6–66.3 %) in LFTs than the phylogeny (1.8–54.2 %). The LCC significantly increased, while LDMC and LTD decreased with increased temperature and reduced precipitation. LPC, LDMC, LMA, and LTD significantly increased, while SLA and LTH decreased with increased aridity. However, leaf elements were not significantly correlated with soil nutrients. The mean annual precipitation was a key factor controlling variations in LFTs at the macroscale in the drylands of China. These findings will provide new insights to better understand the response of LFTs and plants adaptation along environmental gradient in drylands, and will serve as a reference for studying biogeographic patterns of leaf traits.

Chilling Resistance and Physio -Chemical Changes during Cold Acclimation in Foxtail Millet Genotypes

Millets are known as poor man crops, because they grow well in rain-fed or dry land conditions with insufficient soil fertility and water. Food shortages could become more severe in the coming years as the world population rises and arable land is depleted. As a result, various strategies are needed to ensure food security. Millets are also notable for their short growth season. They can reach maturity in as little as 85 days after being sowing. Low temperature is a major environmental factor that can limiting the plant anabolic, metabolic processes and yield globally. Temperature is an extremely important growth limiting factor because it regulates plant physiological and biochemical activity throughout the growth cycle. A field study was scheduled to estimate the low temperatures effect on plant processes such as photosynthesis, respiration, water absorption, chlorophyll stability, and yield. It was done in Rabi’ 2020 and 2021 with factorial randomized block design (FRBD) with three replications. The present study was conducted to determine the low temperature effect on growth analysis and yield of tenai genotypes screening at Agricultural College and Research Institute, Vazhavachanur. Temperature stress, particularly high or low temperatures, can disrupt plant metabolism and shorten the time of distinct plant growth phases. Plants' responses to low temperature exposure can have a significant impact on various growth parameters such as leaf area, leaf area index, crop growth rate, relative water content, photosynthetic efficiency, days to 50% flowering, number of tillers, number of grains per tiller, total dry matter production, and yield. Tenai genotypes TNSi 375 and TNSi 375 recorded higher values of specific leaf area, crop growth rate, specific leaf weight, total chlorophyll content and grain yield than other genotypes under low temperature condition, Tiruvannamali district and Jawathu hill region of Vellore district.

Diversity and mean specific leaf area of Mediterranean woody vegetation changes in response to summer drought across a double stress gradient: The role of phenotypic plasticity

AbstractAimMany aspects of vegetation response to increased drought remain uncertain but it is expected that phenotypic plasticity may be key to early adaptation of plants to environmental stress. In this work we observe the response of specific leaf area (SLA) of woody shrub vegetation to the summer drought typical of the Mediterranean climate. In addition, to observe the possible interaction between the impact of drought and the environmental characteristics of the ecosystems, communities from different edaphic and structural contexts distributed along the double stress gradient of the Mediterranean mountains (high temperature and low precipitation at low elevation; low temperature and high irradiation at high elevation) have been analysed.LocationCentral Mountain range of the Iberian Peninsula.MethodsAlong the entire altitudinal gradient, 33 shrub communities belonging to different habitat typologies (shrublands, rocky areas, hedgerows, understorey) were sampled before and after the passage of summer, both in 2017 and 2019. A total of 1724 individuals and 15,516 leaves were collected and measured to estimate the mean values and diversity of SLA of each community.ResultsThe community‐weighted mean and functional divergence have inverse quadratic relationships with the environmental gradient. Shrub communities at both ends of the gradient have low mean SLA values and high functional divergence of this trait. Summer drought implies a generalised decrease in the mean SLA of the communities throughout the gradient, as well as an alteration in functional richness and uniformity. However, the effect of summer drought on the plant community is mediated by the microenvironmental characteristics of its habitat.ConclusionsDrought acclimatisation of shrub communities through phenotypic plasticity leads to rapid changes in their functional leaf structure. In the long term, our results point to an increase in plant conservative strategies, reduced ecosystem productivity, slower nutrient recycling and the reduction of communities of specific habitats as drought increases.

Evaluation of the Community Land Model-Simulated Specific Leaf Area with Observations over China: Impacts on Modeled Gross Primary Productivity

Specific leaf area (SLA) is a key leaf functional trait associated with the ability to acquire light. Substantial variations in SLA have not been well described in the community land model (CLM) and similar terrestrial biosphere models. How these SLA variations influence the simulation of gross primary productivity (GPP) remains unclear. Here, we evaluated the mismatch in SLA between the CLM4.5 and observed data collected from China and quantified the impacts of SLA variation calculated from both observations and the default values across seven terrestrial biosphere models on modeled GPP using CLM4.5. The results showed that CLM4.5 tended to overestimate SLA values at the top and gradient of the canopy. The higher default SLA values could cause an underestimation of the modeled GPP by 5–161 g C m−2 yr−1 (1%–7%) for temperate needleleaf evergreen tree (NET), temperate broadleaf deciduous tree (BDT), and C3 grass and an overestimation by 50 g C m−2 yr−1 (2%) for temperate broadleaf evergreen tree (BET). Moreover, the observed SLA variation among species ranged from 21% to 59% for 14 plant functional types (PFTs), which was similar to the variation in default SLA values across models (9%–60%). These SLA variations would lead to greater changes in modeled GPP by 7%–19% for temperate NET and temperate BET than temperate BDT and C3 grass (2%–9%). Our study suggested that the interspecific variation in SLA and its responses to environmental factors should be involved in terrestrial biosphere models; otherwise, it would cause substantial bias in the prediction of ecosystem productivity.

Estimation of Genetic Variability Parameters and Parent-offspring Correlation, Regression in Groundnut (Arachis hypogaea L.)

Genetic variability is major component which helps in selecting better genotypes under different environmental conditions, with this aim an experiment was conducted to understand the genetic potential, heritability, genetic advance and traits association of yield contributing characters for F6 and F7 families derived from the cross GKVK-6 × KCG-2 at the University of Agricultural Sciences, Bangalore in an augmented block design along with three checks viz., TMV-2, KCG-6 and KCG-2 during summer and Kharif 2017. Results from analysis of variance (ANOVA) revealed that highly significant differences were observed for all the characters studied. High genetic variability was observed for major yield contributing characters like the number of pods per plant (g), pod yield (g), kernel yield per plant (g), SMK% (sound mature kernel per cent), SCMR (SPAD chlorophyll meter reading) and SLA (specific leaf area) (cm2/g). Narrow difference between GCV (genotypic coefficient of variation) and PCV (phenotypic coefficient of variation) was observed for pods per plant, pod yield, SCMR and SLA and high heritability coupled with moderate genetic advance per cent mean was recorded for pod yield, SCMR and SLA indicating the involvement of additive gene action in controlling these traits. Three superior families were noticed with more pods plant-1, high pod yield plant-1, high kernel yield-1, high shelling (%), high SMK (%), high SCMR value, and low SLA value. Further, these superior families also revealed the presence of high parent offspring regression and intergeneration correlation, implying increased efficiency of selection for most of the traits considered and these were identified to be the important characters that could be used in selection for yield Keywords: GCV, PCV, Heritability, GAM, water use efficiency, Groundnut.

Specific leaf area is lower on ultramafic than on neighbouring non-ultramafic soils

ABSTRACT Background Specific leaf area (SLA) is a core trait within the leaf economic spectrum that describes differences in plant performance and productivity. Research on the sources of variation in the leaf economic spectrum and SLA has primarily focused on climate. Much less is known about SLA variation across unusual edaphic environments, such as on ultramafic soils. Aims To determine the role of ultramafic soils as a driver of SLA variation. Methods We measured SLA for dominant species on paired ultramafic and non-ultramafic soils in five biogeographically distinct regions around the globe and compared mean SLA values to globally reported values. Results SLA was lower on ultramafic than on non-ultramafic soils in all regions, except Puerto Rico, and both climate and soil were important drivers of SLA. For three of the five regions, SLA values on ultramafic soils were lower than the global average. Conclusions Soils can be a major driver of SLA along with climate. Low SLA on ultramafic soil points to selection for stress resistance strategies. Furthermore, in some bioregions, SLA values on ultramafic soils were among the lowest on the planet and thus represent globally rare phenotypes that should be conserved within these unique edaphic habitats.

Divergent response and adaptation of specific leaf area to environmental change at different spatio-temporal scales jointly improve plant survival.

Specific leaf area (SLA) is one of the most important plant functional traits. It integrates multiple functions and reflects strategies of plants to obtain resources. How plants employ different strategies (e.g., through SLA) to respond to dynamic environmental conditions remains poorly understood. This study aimed to explore the spatial variation in SLA and its divergent adaptation through the lens of biogeographic patterns, evolutionary history, and short-term responses. SLA data for 5424 plant species from 76 natural communities in China were systematically measured and integrated with meta-analysis of field experiments (i.e., global warming, drought, and nitrogen addition). The mean value of SLA across all species was 21.8m2 kg-1 , ranging from 0.9 to 110.2m2 kg-1 . SLA differed among different ecosystems, temperature zones, vegetation types, and functional groups. Phylogeny had a weak effect on SLA, but plant species evolved toward higher SLA. Furthermore, SLA responded nonlinearly to environmental change. Unexpectedly, radiation was one of the main factors determining the spatial variation in SLA on a large scale. Conversely, short-term manipulative experiments showed that SLA increased with increased resource availability and tended to stabilize with treatment duration. However, different species exhibited varying response patterns. Overall, variation in long-term adaptation of SLA to environmental gradients and its short-term response to resource pulses jointly improve plant adaptability to a changing environment. Overall SLA-environment relationships should be emphasized as a multidimensional strategy for elucidating environmental change in future research.

Analysis of the functional traits of Quercus cerris L. seedlings in the Molise region (southern Italy)

This study deals with the analysis of seedling fitness in three Quercus cerris wood stands, namely Selva di Castiglione (SC), Bosco della Ficora (BF) and Bosco di San Leo (BSL), developed in different lithological and physiographic conditions and subjected to different forestry practices. A phytosociological study was carried out for analysing the coenological features of the forest stands and to classify these latter from a syntaxonomic point of view. The Pignatti-Ellenberg index (PEi) was calculated on the matrix composed of the phytosociological relevés in order to highlight possible ecological differences or gradients among stands. The phenotypic parameters considered were the stem and root length and the leaf area, whereas the plant functional traits (PFTs) were specific leaf area (SLA), leaf dry matter content (LDMC), leaf thickness (Lth) and chlorophyll content (CHL). The results showed that seedlings coming from different sampling sites exhibited similar values in all the phenotypic parameters. Instead, statistically significant differences were observed in the PFTs. The results suggested that the different adaptation strategies implemented by the seedlings are to be related to the physical environment of the sampling sites and to the different forest structures. The Selva di Castiglione forest stand (SC) exhibited better growth conditions for seedlings testified by higher values of SLA and CHL and lower values of LDMC and Lth. These were interpreted as greater investment in carbon production aimed at rapid development and renewal of the seedling rather than carbon storage aimed at ensuring leaf longevity.

Intra‐ and interspecific variability of specific leaf area mitigate the reduction of community stability in response to warming and nitrogen addition

Global environmental changes are reducing the diversity and affecting the functioning of natural ecosystems as well as their ability to reliably provide ecosystem functions and services to mankind. Many studies have shown that a greater plant diversity can stabilize community productivity against environmental fluctuations. However, most of these studies focused on plant species richness, thus overlooking the potential role of functional traits in stabilizing community productivity against environmental fluctuations. Whether and how functional trait mean and variability influence community stability in response to environmental changes and their relative contributions to community stability are largely unknown. Here, we used a 10‐year experiment to investigate the role of species richness, as well as functional mean and intra‐ and interspecific variability of specific leaf area (SLA) of plants within‐ and among communities in driving community stability in response to nitrogen (N) addition and warming. We found that both N addition and warming reduced the temporal stability of community productivity by reducing species richness and its contribution to species asynchrony and species stability. In contrast, changes in the mean and variability of SLA in response to N addition and warming mitigated the reduction of community stability. Specifically, N addition reduced variation in SLA both by reducing interspecific differences in SLA within communities and differences in mean values of SLA among communities. Warming increased intraspecific differences in SLA among communities, leading to higher species stability that partly buffered the reduction of community stability. Our study demonstrates the role of trait mean and variability in mitigating the reduction of community stability in response to two pervasive global environmental changes. Gaining a deeper understanding of the processes linking global changes and the stability of our ecosystems requires integrating both trait mean values and trait variability.

Shift in microbial communities mediated by vegetation-soil characteristics following subshrub encroachment in a semi-arid grassland

Subshrub encroachment is a frequently occurring phenomenon in arid and semi-arid area, altering the plant community structure and function. However, the effects of the encroachment process on soil bacterial communities are poorly understood on the Loess Plateau, China. In this study, we assessed the changes in soil properties and vegetation characteristics, and their association with alterations in soil bacterial communities in grasslands subjected to different subshrub (Artemisia sacrorum Ledeb.) encroachment intensities (no subshrub encroachment, light subshrub encroachment, moderate subshrub encroachment, and heavy subshrub encroachment). Our results indicated that heavy subshrub encroachment significantly increased plant aboveground biomass and bacterial diversity, but adversely affected plant diversity. Heavy and moderate subshrub encroachment significantly increased soil organic carbon, total nitrogen and water content. Subshrub encroachment at all intensities increased community weighted mean trait values of leaf carbon content, leaf nitrogen content, leaf phosphorus content, specific leaf area, but decreased leaf dry matter content and community functional dispersion. In addition, subshrub encroachment altered the composition of plant and bacterial communities. The partial least squares structural equation model indicated that subshrub encroachment indirectly influenced bacterial communities by affecting vegetation characteristics and soil properties. The determinants of bacterial diversity were vegetation structures (community weighted mean trait values of specific leaf area and plant community composition) and soil properties (organic carbon content, alkaline hydrolysis nitrogen, total phosphorus, available phosphorus, and soil water content). The composition of bacterial community was primarily regulated by plant aboveground biomass and soil properties. Overall, the results of this study improved our understanding of the impact of subshrub encroachment on soil bacteria community on Loess Plateau, and the processes underlying the alterations in the soil bacterial community by subshrub encroachment.

Ecological importance of the Myrtaceae in New Zealand's natural forests

AbstractAimsThe Myrtaceae is a woody family that plays an important role in forest ecosystems globally. The recent spread of myrtle rust, caused by a fungal pathogen (Austropuccinia psidii), from its native South America into New Zealand (NZ), highlights the need to quantify the ecological importance of Myrtaceae in NZ woody ecosystems.LocationNew Zealand.MethodsUsing NZ nationwide forest and shrubland inventory data, collected from 2009 to 2014, we quantified the ecological importance of Myrtaceae based on its richness and abundance relative to co‐occurring woody families. We then explored how climate and forest stand structure affect Myrtaceae importance in general and by tribe and growth form. Finally, we compared functional traits associated with plant growth and reproductive strategies with other dominant woody families and determined Myrtaceae's contributions to community‐weighted mean (CWM) trait values.ResultsMyrtaceae occurred in 74% of the study plots and its importance value was the second highest across the woody families. It was the only one in which climbers substantially contributed to the importance value (17%). Greater Myrtaceae importance values were associated with warmer and more mesic climates and early forest successional stages. Climate associations were similar within tribes and growth forms, whereas forest structure effects varied. Myrtaceae was functionally distinct from most co‐occurring woody families. Contributions to CWM wood density, maximum height, and specific leaf area values were significantly greater than expected from its importance value.ConclusionsMyrtaceae is the second most ecologically important woody family in NZ woody ecosystems. The family has a distinctive functional trait spectrum associated with high wood density and tall stature, ensuring large and enduring carbon stocks. There will potentially be large and deleterious outcomes in forest ecosystems if taxon‐specific pathogens, such as Austropuccinia psidii, spread and significantly reduce Myrtaceae importance.

Taxonomic and functional characteristics of field edge weed communities along a gradient of crop management intensity

The widespread loss of weed diversity and associated ecosystem functions is raising important concerns. Field edges could play a major role in the maintenance of weed functional diversity in arable landscapes as these habitats still harbour high weed diversity, owing to either a reduced farming management intensity and/or to a spillover of species from adjacent perennial field margins. Here, we investigated the taxonomic and functional characteristics of weed species recorded in surveys of field edges and their associated field cores over six consecutive years in 60 arable fields farmed with five crop management strategies. We found that field edges were richer, with species more functionally diverse and composition more stable over years than field core surveys. The distribution of individual functional traits differed between field edges and field cores, with higher values for seed mass and nitrophily (Ellenberg.N), and a wider distribution of specific leaf area values in field edges. The bimodal distribution of plant height and germination period observed in field edges became unimodal in field cores. Field edges harboured species with ecological strategies associated with field cores (ruderal species) plus a conservative strategy which could be explained by a spillover from the adjacent perennial field margins. Crop management strategies impacted field edge flora, though to a lesser extent than the field core flora whereas the functional differences between the field edge and the field core flora were less marked when crop management intensity was lower. These results indicate that field edges harbour a unique assemblage of species and highly contribute to the maintenance of weed diversity in arable landscapes. Future studies should thus focus on the importance of these specific functional traits to the agroecosystem functioning.