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The impact of fire on above‐ground biomass has significant consequences on soil carbon (C) dynamics, which is essential in predicting the global C budget during the Anthropocene. However, there is considerable spatiotemporal variability in the directions and magnitudes of fire effects on soil respiration, and the drivers associated with these effects are not well understood.Here, we conducted a global meta‐analysis of 1327 individual observations from 170 studies to determine the extent to which fire influenced soil total respiration (Rs), heterotrophic respiration (Rh) and autotrophic respiration (Ra).We found fires reduced Rs, Rh and Ra, with an average effect of −11.0%, −17.5% and −40.6%, compared with unburnt sites. Specifically, wildfires significantly reduced Rs and Rh (−20.4% and −25.0%, respectively), and prescribed fire significantly decreased Ra (−74.8%). The influences of fire on Rs and its components were moderated by fire severity, season, type, climate zones and biomes. After several years from the time of the fire, the negative effects of fire on Rs diminished and then recovered to a state not significantly different from unburnt sites; Rh exhibited a similar but decayed temporal response. Similarly, the negative effects on Ra disappeared after 3 years following the latest fire. The magnitude of the effect on Rs was strongly associated with soil temperature, cation exchange capacity, total nitrogen (N) content and N‐acquiring enzyme activity. In contrast, the magnitude of the effect on Rh significantly changed with pH, bulk density, texture, soil C and nutrient contents, and C‐acquiring enzyme activity.Our findings advance the understanding of the inhibition and associated mechanisms of fire on Rs and its components, highlighting the need for new research efforts to predict the spatial‐temporal shifts in underground C‐cycling induced by fire. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Climate‐induced changes in tree mortality, recruitment and growth have been extensively observed in forests worldwide. However, there is still a lack of quantitative understanding regarding how tree demography responds to environmental factors, particularly different water conditions, and how plant functional traits contribute to interspecific differences in this response.Using data collected from a forest monitoring plot, meteorological observations and trait measurements on Barro Colorado Island in Panama—one of the most studied sites, we investigated the mortality, recruitment, growth and population dynamics of 165 tree species from 1990 to 2014 and examined the influence of functional traits in determining the interspecific differences in tree demography. We also employed parametric accelerated failure time models to assess the impact of environmental conditions, functional traits and individual tree characteristics on tree survival time.We find that water stress drives the temporal dynamics of tree demography. During the high water stress period, the increase in mortality rates and decrease in recruitment rates caused negative population changes for species. In contrast, the increase in recruitment rates and decline in mortality rates during the low water stress period positively affected the population of species. Wood density and P50 (xylem water potential at 50% loss of maximum hydraulic conductivity) are significantly correlated with species‐level mortality, recruitment and growth rates, indicating that traits related to resource allocation and hydraulic safety dictate the interspecific differences in demographic rates.Our results demonstrate that water stress and traits related to resource allocation and hydraulic safety jointly mediate tree demography in this tropical forest. High mortality and low recruitment under high water stress may especially cause a decline in fast‐growing species. Therefore, timely recovery of recruitment under favourable water conditions is crucial for the forest dynamics. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Copyright of Functional Ecology is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Climate, disturbance, vegetation response and their interaction are key factors in predicting the distribution and function of ecosystems across landscapes. A range of factors, operating through different pathways, are amplifying the feedbacks in this three‐way interaction.In the western USA, the relative strength of the influence of climate versus vegetation on fire activity varies spatially, realizing a diversity of fire regimes and fire‐selected species traits under historical conditions of climate–fire–vegetation interactions.Human intervention, via land use and fire‐exclusion, has homogenized frequent‐fire‐adapted forests in terms of structure and composition. Climate change is reinforcing the homogenization directly via increasing temperatures and drought and indirectly through climate‐driven tree mortality. The net effect will be forming novel climate–fire–vegetation interactions that act to homogenize fire regimes and catalyse large‐scale forest loss.While long‐term persistence of tree species in a given location may not be possible due to directional change of climate, slowing the rate of wildfire‐driven forest cover loss and maximizing the in‐situ persistence of a diversity of species will allow forest ecosystems to respond more incrementally to changing climate and provide an opportunity for ecosystem reassembly to occur from a large pool of species.As climate continues to change, management to resist wildfire‐driven forest cover loss may hinge on reducing forest density and creating a higher level of heterogeneity to reach the resistance and resilience exhibited by pre‐fire‐exclusion forests. Management operations should better leverage disturbance while strategically deploying silvicultural treatments to increase managed and prescribed fire.Further research is needed to improve our capacity for quantifying key mechanisms and system responses involved in the climate–fire–vegetation interactions and predicting how best to allocate resources to manage for functional forests. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Root‐associated fungi play a critical role in plant ecophysiology, growth and subsequent responses to disturbances, so they are thought to be particularly instrumental in shaping vegetation dynamics after fire in the boreal forest. Despite increasing data on the distribution of fungal taxonomic diversity through space and time in boreal ecosystems, there are knowledge gaps with respect to linking these patterns to ecosystem function and process.Here we explore what is currently known about postfire root‐associated fungi in the boreal forest. We focus on wildfire impacts on mycorrhizal fungi and the relationships between plant–fungal interactions and forest recovery in an effort to explore whether postfire mycorrhizal dynamics underlie plant–soil feedbacks that may influence fire‐facilitated vegetation shifts.We characterize the mechanisms by which wildfire influences root‐associated fungal community assembly. We identify scenarios of postfire plant–fungal interactions that represent putative positive and negative plant–soil feedbacks that may impact successional trajectories. We highlight the need for empirical field observations and experiments to inform our ability to translate patterns of postfire root‐associated fungal diversity to ecological function and application in models.We suggest that understanding postfire interactions between root‐associated fungi and plants is critical to predict fire effects on vegetation patterns, ecosystem function, future landscape flammability and feedbacks to climate. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

The permafrost regions of the boreal forest store a large amount of carbon, which can be affected by ecological disturbance, especially the interference of forest fires. Understanding the dynamic responses of the post‐fire soil fungal community is essential for predicting soil carbon dynamics.We used a post‐fire chronosequence (areas with 3, 25, 46 and >100 years post fire [ypf]) in Canadian boreal forests with continuous permafrost to examine the responses of fungal communities and fungal genes associated with biogeochemical cycling to fire in the surface and near‐surface permafrost layers (0–5, 5–10 and 10–30 cm depth). We hypothesized that as the forest recovers from fire, the fungal communities and functional genes associated with biogeochemical cycling will also recover temporally and spatially, which will in turn affect soil carbon storage.Our results demonstrate that the fire has long‐term effects on fungal communities and functions in the surface and near‐surface soils. The fungal species richness in the 0–5 and 5–10 cm soil layers increased with time since fire, which required at least 46 years to recover to pre‐fire levels. Ascomycota in each of the soil layers in the recently burned area (3 ypf) and ericoid mycorrhizas Oidiodendron maius in the 10–30 cm soil layer in the control area were recognized as indicator taxa.The examination of functional genes revealed that the diversity of potential genes and the expression of genes related to carbon degradation (e.g. chitinase, cellobiase, exoglucanase and endoglucanase) in recently burned area increased in the surface soil, whereas, decreased in the deep soil, suggesting the fire affect the loss of carbon differently in the surface and deep soils in the early stages after fire.In conclusion, the fires significantly altered the fungal communities and functional genes related to carbon storage along the soil vertical gradients and along the post‐fire chronosequence. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Tropical forest responses to variation in water availability, which are critical for understanding and predicting the effects of climate change, depend on trait variation among trees.We quantified interspecific and intraspecific variation in 18 branch, leaf and stomatal traits for 19–72 dominant tree species along a local topographic gradient in an aseasonal Amazon terra firme forest, and tested trait relationships with tree size, elevation, and species' topographic associations. We further tested whether correlation and coordination of traits vary among trees, among species and/or among trees within species.Intraspecific trait variation was substantial and exceeded interspecific variation in 10 of 18 traits. For leaf acquisition traits, intraspecific variation was mainly related to tree topographic elevation, while most of the variation in branch, leaf and stomatal traits was related to tree size. Interspecific variation showed no clear relationships with species' habitat association. Although trait correlations and coordinations were generally maintained among trees and among species, bivariate relationships varied among trees within species, across habitat association classes and across tree size classes.Our results demonstrate the magnitude and importance of intraspecific trait variation in tropical trees, especially as related to tree size. Furthermore, these results suggest that previous findings relating interspecific variation with topographic association in seasonal forests do not necessarily generalize to aseasonal forests. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Copyright of Functional Ecology is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Photosynthetic traits suggest that shade tolerance may explain the contrasting success of two conifer taxa, Podocarpaceae and Pinaceae, in tropical forests. Needle‐leaved species from Pinus (Pinaceae) are generally absent from tropical forests, whereas Pinus krempfii, a flat‐leaved pine, and numerous flat‐leaved Podocarpaceae are abundant. Respiration (R) traits may provide additional insight into the drivers of the contrasting success of needle‐ and flat‐leaved conifers in tropical forests.We measured the short‐term respiratory temperature (RT) response between 10 and 50°C and foliar morphological traits of three needle‐ and seven flat‐leaved conifer species coexisting in a tropical montane forest in the Central Highlands of Vietnam containing notable conifer diversity. We fit a lognormal polynomial model to each RT curve and extracted the following three parameters: a (basal R), and b and c (together describing the shape of the response).Needle‐leaved species (Pinus kesiya, Pinus dalatensis and Dacrydium elatum) had higher rates of area‐based R at 25°C (R25‐area) as well as higher area‐based modelled basal respiration (a) than flat‐leaved species (P. krempfii, Podocarpus neriifolius, Dacrycarpus imbricatus, Nageia nana, Taxus wallichiana, Keteeleria evelyniana and Fokienia hodginsii). No significant differences were found between needle‐ and flat‐leaved species in mass‐based R25 (R25‐mass) or in the shape of the RT response (b and c); however, interspecific differences in R25‐mass, R at nighttime temperature extremes (R4.1 and R20.6) and leaf traits were apparent.Differences in R25‐area and a suggest that needle‐leaved foliage may be more energetically costly to maintain than flat‐leaved foliage, providing new insight and additional support for the hypothesis that shade tolerance is an important driver of Podocarpaceae success and Pinaceae absence in the majority of tropical forests.Interspecific differences in R25‐mass and leaf traits highlight that varying ecological strategies are employed by conifers to coexist and survive in the Central Highlands of Vietnam. Ultimately, these data further our understanding of current conifer biogeographical distributions and underscore the need for additional studies to elucidate the effects of extreme temperature events on the continued survival of conifers in this unique forest. A free Plain Language Summary can be found within the Supporting Information of this article. [ABSTRACT FROM AUTHOR]

Many leaf traits strongly vary with tree size and environmental factors, but the importance of these factors to intraspecific variations of leaf traits in forest trees has rarely been simultaneously evaluated.We measured needle longevity and specific leaf area (SLA) and nitrogen (N) content of every needle age (0‐ to 4‐year old) for 65 individuals with 0.3–100 cm diameter at breast height (DBH) for an evergreen coniferous species, Pinus koraiensis Sieb. et Zucc., in Northeast China. We simultaneously evaluated the effects of tree size (DBH or tree height) and environment factors (light intensity, soil N content and water availability) on the needle longevity, SLA, foliage N content as well as the slopes of regressions of SLA and foliage N content against needle age.All of the studied leaf traits and slopes of regressions of SLA and foliage N content against needle age were significantly related to tree size. Tree height had a greater impact on SLA and area‐based leaf N content (Narea), whereas DBH was more important for needle longevity and mass‐based leaf N content (Nmass). The environment variables, light intensity, soil N content and water availability, were rather minor factors for trait variations compared with tree size. Significant influence of light intensity was found only on needle longevity, and soil N and water availability had no effects on the leaf traits.Our study clearly showed that tree size is an important driver of intraspecific variations in the key leaf traits of P. koraiensis in a natural forest. We also emphasize the importance of DBH or tree height varies depending on leaf traits, suggesting various mechanisms of size effects on the intraspecific variations in leaf traits. We suggest that ecological significance of leaf trait variations needs reconsideration incorporating tree size effect. A free Plain Language Summary can be found within the Supporting Information of this article. [ABSTRACT FROM AUTHOR]

Assessing drought tolerance and the ability of plants to adjust to changes in available water resources is crucial for understanding current and future distributions of plant species. While turgor loss point (πtlp) has been recognized as a direct determinant of drought tolerance in woody plants, information on it for grassland species is largely missing.We first validated a rapid method to estimate πtlp for grassland species, using osmometry measurements (πtlp‐osm) of osmotic potential at full hydration (πo‐osm), originally proposed for woody species. We confirmed that πo‐osm was tightly positively related to πtlp measured by the classic pressure–volume curve (πtlp‐pv). Cell wall elasticity was not important in the maintenance of turgor and neither specific leaf area nor leaf dry matter content influenced πtlp.We then studied the relationship between πtlp‐osm measured under controlled conditions and species' soil moisture affinity (Ellenberg indicator values) in 40 diverse grassland species from the full range of soil moisture conditions found in temperate grasslands. On a subset of 12 species, we studied the adjustment in πtlp‐osm to drought stress and recovery from drought.We hypothesized that dry grassland species are better adapted to drier conditions by having comparatively higher leaf drought tolerance (more negative πtlp) and a better ability to adjust to acute drought stress.We found that πtlp‐osm was unrelated to species' soil moisture affinity. However, all species developed higher leaf drought tolerance by decreasing πtlp‐osm after seven weeks of drought stress. After only one week of recovery, all species reduced the leaf drought tolerance back to the πtlp‐osm level comparable with non‐stressed plants.Our results considerably extend the relationship between πo‐osm and πtlp, originally defined for woody species, and thus propose a yet unexploited direct method for assessing leaf drought tolerance via turgor loss point in herbaceous species. However, the lack of relationship between πtlp and soil moisture affinity suggests that, unlike in woody plants, leaf‐level drought tolerance in grassland plants does not fully translate into whole‐plant drought resistance, suggesting an importance of other drought resistance strategies. A plain language summary is available for this article. [ABSTRACT FROM AUTHOR]

The application of functional traits to predict and explain plant species' distributions and vital rates has been a major direction in functional ecology for decades, yet numerous physiological traits have not yet been incorporated into the approach.Using commonly measured traits such as leaf mass per area (LMA) and wood density (WD), and additional traits related to water transport, gas exchange and resource economics, including leaf vein, stomatal and wilting traits, we tested hypotheses for Hawaiian wet montane and lowland dry forests (MWF and LDF, respectively): (1) Forests would differ in a wide range of traits as expected from contrasting adaptation; (2) trait values would be more convergent among dry than wet forest species due to the stronger environmental filtering; (3) traits would be intercorrelated within "modules" supporting given functions; (4) relative growth rate (RGR) and mortality rate (m) would correlate with a number of specific traits; with (5) stronger relationships when stratifying by tree size; and (6) RGR and m can be strongly explained from trait‐based models.The MWF species' traits were associated with adaptation to high soil moisture and nutrient supply and greater shade tolerance, whereas the LDF species' traits were associated with drought tolerance. Thus, on average, MWF species achieved higher maximum heights than LDF species and had leaves with larger epidermal cells, higher maximum stomatal conductance and CO2 assimilation rate, lower vein lengths per area, higher saturated water content and greater shrinkage when dry, lower dry matter content, higher phosphorus concentration, lower nitrogen to phosphorus ratio, high chlorophyll to nitrogen ratio, high carbon isotope discrimination, high stomatal conductance to nitrogen ratio, less negative turgor loss point and lower WD. Functional traits were more variable in the MWF than LDF, were correlated within modules, and predicted species' RGR and m across forests, with stronger relationships when stratifying by tree size. Models based on multiple traits predicted vital rates across forests (R2 = 0.70–0.72; p < 0.01).Our findings are consistent with a powerful role of broad suites of functional traits in contributing to forest species' distributions, integrated plant design and vital rates. A plain language summary is available for this article. Plain Language Summary [ABSTRACT FROM AUTHOR]

Many studies have examined individual environmental drivers of tropical tree species distributions, but edaphic and successional gradients have not been considered simultaneously. Furthermore, determining how functional traits influence species distributions along these gradients may help to elucidate mechanisms behind community assembly.To assess the influence of environmental filtering on tropical dry forest (TDF) tree species distributions, we used forest inventory data from sites with large edaphic and successional gradients in NW Costa Rica. Our goals were to determine (1) whether edaphic or successional factors are more important determinants of the abundance of individual tree species in regenerating TDF, (2) how species‐level functional traits are related to edaphic and/or successional niche associations of tree species and (3) correlations between species‐level edaphic and successional niche associations.The distributions of 82 focal tree species were strongly driven by both edaphic and successional gradients. Overall, 94% of species responded to soil chemistry, 89% to soil texture and 94% to stand age gradients. Some functional traits were correlated with the edaphic and successional niche associations of TDF tree species. Species that specialized on soils with high total nutrient concentrations had higher foliar nutrient concentrations (nitrogen and phosphorus) and lower leaf dry matter content (LDMC). Species with wider stand age niches had lower LDMC and wood density. There were no correlations between edaphic and successional niche optima of TDF tree species.Our results indicate that successional and edaphic gradients concurrently drive community assembly in regenerating TDF. Moreover, our work underscores the importance of considering how the functional characteristics of TDF trees dictate species distributions across environmental gradients. A plain language summary is available for this article. Plain Language Summary [ABSTRACT FROM AUTHOR]

Abstract: Water availability is a key determinant of forest ecosystem function and tree species distributions. While droughts are increasing in frequency in many ecosystems, including in the tropics, plant responses to water supply vary with species and drought intensity and are therefore difficult to model. Based on physiological first principles, we hypothesized that trees with a lower turgor loss point (πtlp), that is, a more negative leaf water potential at wilting, would maintain water transport for longer into a dry season. We measured sapflux density of 22 mature trees of 10 species during a dry season in an Amazonian rainforest, quantified sapflux decline as soil water content decreased and tested its relationship to tree πtlp, size and leaf predawn and midday water potentials measured after the onset of the dry season. The measured trees varied strongly in the response of water use to the seasonal drought, with sapflux at the end of the dry season ranging from 37 to 117% (on average 83 ± 5 %) of that at the beginning of the dry season. The decline of water transport as soil dried was correlated with tree πtlp (Spearman’s ρ ≥ 0.63), but not with tree size or predawn and midday water potentials. Thus, trees with more drought‐tolerant leaves better maintained water transport during the seasonal drought. Our study provides an explicit correlation between a trait, measurable at the leaf level, and whole‐plant performance under drying conditions. Physiological traits such as πtlp can be used to assess and model higher scale processes in response to drying conditions. A plain language summary is available for this article. [ABSTRACT FROM AUTHOR]

Abstract: “What controls the distribution and abundance of organisms”? This question, at the heart of the dynamics of ecological communities, would have been familiar to the earliest ecologists. Having lain effectively abandoned for many years, community dynamics today is a vibrant research topic of great conceptual interest with practical import for conservation, ecological management, ecosystem services and the responses of ecological communities to climate change. We describe how modern coexistence theory can be used to predict community dynamics through the use of demography. We explore the challenges that limit the deployment of this demographic framework, and the tools from phylogenetic and functional ecology that have been used to surmount them. Finding existing tools not altogether sufficient, we propose the use of “hard” functional traits and physiological tolerances of environmental conditions and low resource availability to extend the demographic framework so that the dynamics of a broader range of ecological communities can be accurately predicted. We illustrate these new approaches with two case studies. Given the urgent need to accurately forecast the dynamics of ecological communities, we hope that many ecologists will adopt these tools. A plain language summary is available for this article. [ABSTRACT FROM AUTHOR]