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Longer growing seasons shift grassland vegetation towards more-productive species
Abstract
Despite advances in plant functional ecology that provide a framework for predicting the responses of vegetation to environmental change, links between plant functional strategies and elevated temperatures are poorly understood. Here, we analyse the response of a species-rich grassland in northern England to two decades of temperature and rainfall manipulations in the context of the functional attributes of 21 coexisting species that represent a large array of resource-use strategies. Three principal traits, including body size (canopy height), tissue investment (leaf construction cost), and seed size, varied independently across species and reflect tradeoffs associated with competitiveness, stress tolerance, and colonization ability. Unlike past studies, our results reveal a strong association between functional traits and temperature regime; species favoured by extended growing seasons have taller canopies and faster assimilation rates, which has come at the expense of those species of high tissue investment. This trait-warming association was three times higher in deep soils, suggesting species shifts have been strongly mediated by competition. In contrast, vegetation shifts from rainfall manipulations have been associated only with tissue investment. Functional shifts towards faster growing species in response to warming may be responsible for a marginal increase in productivity in a system that was assumed to be nutrient-limited.
... Studies of shifts in plant phenology as influenced by changes in environmental conditions provide some of the most compelling, but understudied, indications that plant phenology and species dominance may be intimately linked (CaraDonna et al., 2014;Fridley et al., 2016). Changes in plant phenology may determine the biotic and abiotic environmental conditions experienced during each developmental phase (Augspurger, 2013;Forrest and Miller-Rushing, 2010;Parmesan, 2006). ...
... In addition, species have consistently shown divergent phenological responses to climate warming, rather than shifting unidirectionally (Sherry et al., 2007). These highly differentiated species-specific phenological responses to warming may have substantial, but underexplored, impacts on species turnover (Fridley et al., 2016;Kraft et al., 2015;Post et al., 2016;Zohner et al., 2018). Therefore, it is critical to integrate impacts of species-specific phenological firsts and phenological lasts to better understand phenological responses to climate warming and the consequences this may have for plant species turnover. ...
... Second, lengthening of the growing season or flower duration could help species avoid potential trophic mismatches (CaraDonna et al., 2014;Fridley et al., 2016;Renner and Zohner, 2018). For mutualistic plant-animal relationships, for example, phenological mismatches between flowers and pollinators could have crucial effects on plant community composition through reduced plant fitness over time (Elzinga et al., 2007;Schermer et al., 2020;Schmidt et al., 2016). ...
... Climate change is reshaping plant communities through increasing extinction risk Urban, 2015), introducing novel colonists through species range expansions (Savage & Vellend, 2015;Steinbauer et al., 2018) and causing shifts in abundance within communities . Climate change experiments often find that moist temperate grassland plant communities shift towards taller, more productive species as climates warm (Elmendorf, Henry, Hollister, Björk, Bjorkman, et al., 2012;Fridley et al., 2016). However, considerable variation among species and communities in their responses suggests that the effects of climate change can be highly context-dependent (Dunne et al., 2004;Vandvik et al., 2020). ...
... Additionally, intraspecific variation in our system was less than interspecific variations (Appendix S1), suggesting our trait sampling protocols provided useful data for prediction, as we found. Alternatively, past work suggests that traits may be most useful when viewed as syndromes of species measured in a common environment that reflect differences across species (Fridley et al., 2016;Grime et al., 1997;Reich, 2014;Shipley et al., 2016). However, this trait screening method would have been logistically and financially difficult in our system given the number of potential species (> 140). ...
Aim
Climate change impacts on biota are variable across sites, among species and throughout individual species' ranges. Niche theory predicts that population performance should decline as site climate becomes increasingly different from the species' climate niche centre, though studies find significant variation from these predictions. Here, we propose that predictions about climate responses can be improved by incorporating species' trait information.
Location
Europe.
Methods
We used observations of plant species abundance change over time to assess variation in climate difference sensitivity (CDS), defined as how species performance (colonization, extinction and abundance change) relates to the difference of site climate from the mean temperature and precipitation of each species' range. We then investigated if leaf economics, plant size and seed mass traits were associated with the species' CDS.
Results
Species that performed better (e.g. increased in abundance) towards sites progressively cooler than their niche centre were shorter and had more resource‐acquisitive leaves (i.e. lower leaf dry matter content or LDMC) relative to species with zero or the opposite pattern of temperature difference sensitivity. This result supports the hypothesis that if sites cooler than niche centres are more stressful for a species, then shorter stature is advantageous compared with taller species. The LDMC result suggests the environment selects for more resource‐acquisitive leaf strategies towards relatively cooler climates with shorter growing seasons, counter to expectations that conservative strategies would be favoured in such environments. We found few consistent relationships between precipitation difference sensitivities and traits.
Main Conclusions
The results supported key a priori foundations on how trait‐based plant strategies dictate species responses to climate variation away from their niche centre. Furthermore, plant height emerged as the most consistent trait that varied with species CDS, suggesting height will be key for theory development around species response to climate change.
... We used soils from chronic drought and irrigation treatments within the Buxton Climate Change Impacts Study, where temperature and rainfall have been experimentally manipulated since 1993 36 . Such prolonged treatments (25 years) represent a strong selective pressure on both plants and soil microbial communities [37][38][39] . Previous work at the study site demonstrated that drought-mediated changes in soil microbial communities were linked to changes in the plant community via shifts in plant traits representing altered resource quality for soil microorganisms 37,38,40 . ...
... Such prolonged treatments (25 years) represent a strong selective pressure on both plants and soil microbial communities [37][38][39] . Previous work at the study site demonstrated that drought-mediated changes in soil microbial communities were linked to changes in the plant community via shifts in plant traits representing altered resource quality for soil microorganisms 37,38,40 . Hence, chronic climate treatments have altered soil microbial community structure and we hypothesized that soil microbial communities from long-term drought plots would respond more strongly to plant stress hormones, compared with soil microbes from irrigated or control plots. ...
Drought imposes stress on plants and associated soil microbes, inducing coordinated adaptive responses, which can involve plant–soil signalling via phytohormones. However, we know little about how microbial communities respond to phytohormones, or how these responses are shaped by chronic (long-term) drought. Here, we added three phytohormones (abscisic acid, 1-aminocyclopropane-1-carboxylic acid, and jasmonic acid) to soils from long-term (25-year), field-based climate treatments to test the hypothesis that chronic drought alters soil microbial community responses to plant stress signalling. Phytohormone addition increased soil respiration, but this effect was stronger in irrigated than in droughted soils and increased soil respiration at low phytohormone concentrations could not be explained by their use as substrate. Thus, we show that drought adaptation within soil microbial communities modifies their responses to phytohormone inputs. Furthermore, distinct phytohormone-induced shifts in microbial functional groups in droughted vs. irrigated soils might suggest that drought-adapted soil microorganisms perceive phytohormones as stress-signals, allowing them to anticipate impending drought.
... Climate change experiments and distribution modeling have been key for understanding and predicting the population-and community-level consequences of climate change. For instance, long-term in situ warming experiments suggest climate warming will shift vascular plant communities toward more competitive and productive species in a temperate grassland (Fridley et al., 2016) and will increase the dominance of shrubs in a montane temperate grassland (Harte et al., 2015). Turf transplant experiments, where whole plant communities are moved to new sites in the direction of projected climate change, suggest that increased temperatures with climate change may depress the population growth of cold-adapted plant species (Töpper et al., 2018) and that taller, more clonal species will increase in abundance with warming (Guittar et al., 2016). ...
... Turf transplant experiments, where whole plant communities are moved to new sites in the direction of projected climate change, suggest that increased temperatures with climate change may depress the population growth of cold-adapted plant species (Töpper et al., 2018) and that taller, more clonal species will increase in abundance with warming (Guittar et al., 2016). Such climate manipulations are valuable in allowing causal inferences but species' responses can be difficult to generalize as outcomes often vary considerably depending on the abiotic and/or biotic contexts of a particular experiment (Dunne et al., 2004;Vandvik et al., 2020) or species-specific traits or strategies (Fridley et al., 2016). An alternative approach, species distribution modeling, predicts where a species will occur with further climate change based on the species' current/historical distribution and associated climate data (Dyderski et al., 2018;Zhang et al., 2014). ...
Context‐dependencies in species’ responses to the same climate change frustrate attempts to generalize and make predictions based on experimental and observational approaches in biodiversity science. Here, we propose predictability may be enhanced by explicitly incorporating macroecological context into analyses of species’ responses to climate manipulations. We combined vascular plant species’ responses to an eight‐year, 12‐site turf‐transplant climate change experiment set in southwestern Norway with climate niche data from the observed 151 species. We used the difference between a species’ mean climate across their range and climate conditions at the transplant site (“climate differences”) to predict colonization probability, extinction probability, and change in abundance of a species at a site. In analyses across species that ignore species‐specific patterns, colonization success increased as species’ distribution optima were increasingly warmer than the experimental target site. Extinction probability increased as species’ distribution optima were increasingly colder than the target site. These patterns were reflected in change in abundance analyses. We found weak responses to increased precipitation in these oceanic climates. Climate differences were better predictors of species’ responses to climate manipulations than range size. Interestingly, similar patterns were found when analyses focused on variation in species‐specific responses across sites. These results provide an experimental underpinning to observational studies that report thermophilization of communities and suggest that space‐for‐time substitutions may be valid for predicting species’ responses to climate warming, given other conditions are accounted for (e.g., soil nutrients). Finally, we suggest that this method of putting climate change experiments into macroecological context has the potential to generalize and predict species’ responses to climate manipulations globally.
... Thus, site fertility and associated plant functional types could determine the rate of plant community changes under climatic change. In the longer term, the communities on infertile sites showed more pronounced changes in composition but it was suggested that these communities would still respond relatively weakly to climatic changes (Fridley, Lynn, Grime, & Askew, 2016;Grime et al., 2008). These findings from British grasslands led to a development of a general view upon the role of site fertility as a key property influencing climate sensitivity of plant communities and might represent one of the few emerging generalizations on how plant communities respond to climate change (Harrison, Damschen, Fernandez-Going, Eskelinen, & Copeland, 2015). ...
... It is widely acknowledged that predicting the effects of climate change on plant communities is notoriously difficult due to complex relations between environmental conditions and multispecies assemblages (Fridley et al., 2016). Despite these difficulties, resourcebased plant strategy theories may allow some general predictions of climate change effects. ...
Abstract Experimental evidence shows that site fertility is a key modulator underlying plant community changes under climate change. Communities on fertile sites, with species having fast dynamics, have been found to react more strongly to climate change than communities on infertile sites with slow dynamics. However, it is still unclear whether this generally applies to high‐latitude plant communities in natural environments at broad spatial scales. We tested a hypothesis that vegetation of fertile sites experiences greater changes over several decades and thus would be more responsive under contemporary climate change compared to infertile sites that are expected to show more resistance. We resurveyed understorey communities (vascular plants, bryophytes, and lichens) of four infertile and four fertile forest sites along a latitudinal bioclimatic gradient. Sites had remained outside direct human disturbance. We analyzed the magnitude of temporal community turnover, changes in the abundances of plant morphological groups and strategy classes, and changes in species diversity. In agreement with our hypothesis, temporal turnover of communities was consistently greater on fertile sites compared to infertile sites. However, our results suggest that the larger turnover of fertile communities is not primarily related to the direct effects of climatic warming. Furthermore, community changes in both fertile and infertile sites showed remarkable variation in terms of shares of plant functional groups and strategy classes and measures of species diversity. This further emphasizes the essential role of baseline environmental conditions and nonclimatic drivers underlying vegetation changes. Our results show that site fertility is a key determinant of the overall rate of high‐latitude vegetation changes but the composition of plant communities in different ecological contexts is variously impacted by nonclimatic drivers over time.
... The impacts of drought on grassland net primary production at a global scale showed that regional differences existed in the effects of drought on vegetation productivity (Wang et al., 2019a). For example, the changes in growing season length due to warming would increase the productivity of grasslands even under increasing aridity in North America (Fridley et al., 2016;Hufkens et al., 2016). Thus, how and to what degree the spring phenological changes affect grassland productivity under droughts need to be further investigated. ...
Increasing drought is one major consequence of ongoing global climate change and is expected to cause significant changes in vegetation phenology, especially for naturally vulnerable ecosystems such as grassland. However, the linkage between the response characteristic of green-up date (GUD) to drought and background climate remains largely unknown. Here, we focused on how the GUD of Mongolian grassland responds to extreme drought events (EDE). We first extracted the GUD from the MODIS Enhanced Vegetation Index data during 2001-2020 and identified the preseason EDE using the standardized precipitation evapotranspiration index data. Subsequently, we quantified the response of GUD to preseason EDE (DGUD) in each pixel as the difference in GUD between drought and normal years. The effect of 12 factors on DGUD was analyzed using the random forest algorithm. The results showed that the GUD under EDE may delay or advance by >20 days compared to normal years. For the regions with mean annual temperature > -2 °C, the GUD was delayed under EDE due to the dominant role of water restriction on GUD, while the GUD was advanced under EDE in colder areas due to the warmer temperature during drought. However, the magnitude of delay in GUD under drought was greater in regions with less precipitation and more severe droughts. Our results could help to develop appropriate management strategies to mitigate the impacts of drought on grasslands.
... These are traits associated with resourceacquisitive strategy (Reich, 2014;Wright et al., 2004). Our findings suggest that both seed limitation and nutrient availability can constrain community productivity and prevent shifts in community composition towards resource-acquisitive functional traits, in particular in the context of increasing temperatures (Fridley et al., 2016). Taken together, our results highlight the importance of herbivores, soil nutrient availability and temperature in controlling how dispersal limitation and novel species invasion impact plant community productivity. ...
Seed limitation can narrow down the number of coexisting plant species, limit plant community productivity, and also constrain community responses to changing environmental and biotic conditions. In a 10‐year full‐factorial experiment of seed addition, fertilisation, warming and herbivore exclusion, we tested how seed addition alters community richness and biomass, and how its effects depend on seed origin and biotic and abiotic context. We found that seed addition increased species richness in all treatments, and increased plant community biomass depending on nutrient addition and warming. Novel species, originally absent from the communities, increased biomass the most, especially in fertilised plots and in the absence of herbivores, while adding seeds of local species did not affect biomass. Our results show that seed limitation constrains both community richness and biomass, and highlight the importance of considering trophic interactions and soil nutrients when assessing novel species immigrations and their effects on community biomass.
... In addition, senescence in the form of leaf coloration starts on average later (Menzel and Fabian, 1999;Menzel et al., 2020). This prolonged growing season may impact species community composition, the global carbon cycling, as well as ecosystem functions like productivity (White et al., 1999;Churkina et al., 2005;Richardson et al., 2010;Fridley et al., 2016). ...
... Field-based warming experiments have repeatedly supported this hypothesis. For instance, in situ winter warming increased the abundance of taller, more competitive species by extending the growing season, thus increasing plant biomass production in a northern England grassland (Fridley et al., 2016). Twenty-three years of warming in a subalpine grassland of the Colorado Rockies increased shrub biomass over ambient plots and caused sharp initial decreases in soil organic carbon associated with declines in forbs (Harte et al., 2015). ...
Both theory and prior studies predict that climate warming should increase attack rates by herbivores and pathogens on plants. However, past work has often assumed that variation in abiotic conditions other than temperature (e.g. precipitation) do not alter warming responses of plant damage by natural enemies. Studies over short time periods span low variation in weather, and studies over long time‐scales often neglect to account for fine‐scale weather conditions.
Here, we used a 20+ year warming experiment to investigate if warming affects on herbivory and pathogen disease are dependent on variation in ambient weather observed over 3 years. We studied three common grass species in a subalpine meadow in the Colorado Rocky Mountains, USA. We visually estimated herbivory and disease every 2 weeks during the growing season and evaluated weather conditions during the previous 2‐ or 4‐week time interval (2‐week average air temperature, 2‐ and 4‐week cumulative precipitation) as predictors of the probability and amount of damage.
Herbivore attack was 13% more likely and damage amount was 29% greater in warmed plots than controls across the focal species but warming treatment had little affect on plant disease. Herbivory presence and damage increased the most with experimental warming when preceded by wetter, rather than drier, fine‐scale weather, but preceding ambient temperature did not strongly interact with elevated warming to influence herbivory.
Disease presence and amount increased, on average, with warmer weather and more precipitation regardless of warming.
Synthesis . The effect of warming over reference climate on herbivore damage is dependent on and amplified by fine‐scale weather variation, suggesting more boom‐and‐bust damage dynamics with increasing climate variability. However, the mean effect of regional climate change is likely reduced monsoon rainfall, for which we predict a reduction in insect herbivore damage. Plant disease was generally unresponsive to warming, which may be a consequence of our coarse disease estimates that did not track specific pathogen species or guilds. The results point towards temperature as an important but not sufficient determinant and regulator of species interactions, where precipitation and other constraints may determine the affect of warming.
... We expected the following: (1) Given that traits which allow fast acquisition of resources and growth rate (e.g. high photosynthetic rate and low leaf mass per area [LMA]) can be detrimental when resources are limiting, and advantageous when not, (Fridley et al., 2016;Zhang et al., 2020), species with these resource-acquisitive traits should be most responsive to the manipulations (either suffering e.g. due to water shortage or benefiting e.g. from a longer growing season). ...
Understanding the traits mediating species' responses to climate change is a cornerstone for predicting future community composition and ecosystem function.
Although species' eco‐physiological properties determine their response to environmental change, most trait‐based studies focus on a small subset of easily measured morphological traits as proxies for physiology. This choice may limit our ability to predict the impacts of climate change on species' demography, and obscure the underlying mechanisms.
We conducted a transplantation experiment along a 1000‐m elevation gradient in the Alps to quantify the degree to which changes in plant abundance due to climate warming were predicted by eco‐physiological performance versus common morphological traits.
Physiological measurements revealed that warming favoured species with a conservative leaf‐level water use strategy whereas species whose leaf‐level water use was more ‘wasteful’ were more likely to suffer from the warmer and drier climate. Nevertheless, the predictive power of physiological traits did not exceed that of morphological traits.
Our results, therefore, show that while easily measured morphological traits can successfully predict plant abundance responses to climate, eco‐physiological approaches are needed to understand the underlying mechanism.
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... "Interspecific association" refers to the interactions and spatial relationships among different species occupying a habitat, which can provide prominent insights into community assembly as well as determine community structure and function [1][2][3][4]. This concept is widely used to quantify interspecific relationships and to infer ecological processes underlying community assembly [5][6][7][8][9]. Previous studies have shown that the interspecific associations of plant communities are not static and are usually constrained by a variety of influencing factors such as interspecific competition [10], environmental changes [11,12], and research scales [8]. ...
“Interspecific associations” refers to the interrelationship among different species in a particular spatial distribution, which plays an important role in species distribution, community assembly, and responses to environmental changes. However, the strength and/or direction of interspecific associations may vary with environmental gradients and scales. To understand the effects of habitat types and research scales on interspecific associations in subtropical forests, we modeled the interspecific associations for more than 15,000 individuals representing 74 co-occurring species from three habitat types and three scales by using the variance ratio and the Spearman rank correlation coefficient. We found that overall interspecific associations at a community level exhibited significant positive associations for most habitat types and scales. Moreover, interspecific associations of pairwise species have strong habitat dependence, and the association strengths decreased with the increase in elevation (change in habitat types). However, the scale dependence of pairwise interspecific associations varies with habitat types. The strength of interspecific associations increased with the increasing scales (10 m × 10 m, 20 m × 20 m, and 40 m × 40 m) at low-valleys and mid-hillside habitats, while the scale-dependent effect was not detected at high-ridges. In conclusion, our study highlights the importance of environmental gradients and research scales on interspecific associations in diverse subtropical forests, and environmental gradients and research scales should be considered in future studies.
... In wet environments, plants usually maintain a relatively higher stomatal conductance to maximize carbon uptake (as water stress is not limiting their functioning), whereas in contrast, plants living in dry environments are prone to maintain a relatively stable and lower stomata conductance to avoid excessive-water loss while retaining lower rates of carbon uptake (McDowell et al., 2008). For example, Fridley et al. (2016) observed increasing grassland productivity due to extended growing season despite increasing aridity. ...
Hysteresis between sub-diurnal actual evaporation (AET) (or one of its components, transpiration) and vapor pressure deficit (VPD) at the species or individual ecosystem level has been extensively studied, but the global variation and seasonal variability of this hysteresis across biomes and climates is yet to be fully explored and the limiting mechanisms remain unclear. We hypothesize that the sub-diurnal AET-VPD hysteresis results from the interplay between evaporative demand and soil moisture supply limitations. To test our hypothesis, we quantify the sub-diurnal AET-VPD hysteresis across a broad range of biomes and climates based on the observations from the 89 FLUXNET sites (703 site-years) across the globe. We find that the magnitude of hysteresis varies with biomes and climates and is mostly attributable to evaporative demand limitation in all ten sampled biomes. In seasonally dry locations, however, low soil moisture availability amplifies the hysteresis during the dry season. Sensitivity analysis using a hydraulic model suggests that most ecosystems exhibiting seasonal drought display a more isohydric behavior during the dry season, while shift toward a more anisohydric response during the wet season. Our findings have important implications for understanding sub-diurnal dynamics between vegetation and its surrounding environment, reducing uncertainties in AET simulation at fine spatial and temporal scales, and improving understanding of the ecosystem response to hydrologic stress.
... Wang et al., 2020). Similarly, global climate change may increase vegetation community complexity in areas with extended growing season length (Fang et al., 2004;Fridley et al., 2016;Jeong et al., 2011), while reduce it in areas with an increasing frequency of extreme climate events (e.g., droughts, floods) (Bronstert, 2003;Fettig et al., 2019;Sankaran, 2019). ...
Vegetation community complexity is a critical factor influencing terrestrial ecosystem stability. China, the country leading the world in vegetation greening resulting from human activities, has experienced dramatic changes in vegetation community composition during the past 30 years. However, how China's vegetation community complexity varies spatially and temporally remains unclear. Here, we examined the spatial pattern of China's vegetation community complexity and its temporal changes from the 1980s to 2015 using two vegetation maps of China as well as more than half a million field samples. Spatially, China's vegetation community complexity distribution is primarily dominated by elevation, although temperature and precipitation can be locally more influential than elevation when they become the factors limiting plant growth. Temporally, China's vegetation community complexity shows a significant decreasing trend during the past 30 years, despite the observed vegetation greening trend. Prevailing climate warming across China exhibits a significant negative correlation with the decrease in vegetation community complexity, but this correlation varies with biogeographical regions. The intensity of human activities have an overall negative influence on vegetation community complexity, but vegetation conservation and restoration efforts can have a positive effect on maintaining vegetation composition complexity, informing the critical role of vegetation management policies in achieving the sustainable development goal.
... This indicates a high degree of consistency between species-level and community-level (pixel-level) phenology variation at Henan Station. Consequently, the herbs growing season was mainly extended (Sun et al., 2020), which could further impact the grassland ecosystem structure and function (Fridley et al., 2016;Leblans et al., 2017). The delayed brown-off dates in most herbs are likely associated with climate conditions. ...
The phenology of alpine grassland on the Qinghai–Tibet Plateau (QTP) is critical to regional climate change through climate–vegetation feedback. Although many studies have examined QTP vegetation dynamics and their climate sensitivities, the interspecific difference in the phenology response to climate change between alpine species is poorly understood. Here, we used a 30-year (1989–2018) record of in situ phenological observation for five typical alpine herbs ( Elymus nutans , Kobresia pygmaea , Plantago asiatica , Puccinellia tenuiflora , and Scirpus distigmaticus ) and associated climatic records at Henan Station in the eastern QTP to examine the species-level difference in spring and autumn phenology and then quantify their climate sensitivities. Our results show that with significantly warming, the green-up dates of herbs were insignificantly shifted, while the brown-off dates in four out of the five herbs were significantly delayed. Meanwhile, the interspecific difference in brown-off dates significantly increased at a rate of 0.62 days/annual from 1989 to 2016, which was three times larger than that in green-up dates (0.20 days/annual). These diverse rates were attributed to the different climate controls on spring and autumn phenology. In particular, green-up dates in most herbs were sensitive to mean surface temperature, while brown-off dates were sensitive to the night surface temperature. Furthermore, brown-off dates are less sensitive to the warming in high ecological niche (with higher herb height and aboveground biomass) herbs than low niche herbs (with lower herb height and aboveground biomass). The increased phenology interspecific difference highlights the complex responses of herbs to future climate change even under the same alpine environment and indicates a potential alternation in the plants community of alpine QTP, which may further influence the regional climate–vegetation feedback.
... Further, herbivore populations and communities are dependent on the amount and nutritional quality of available plant matter for their metabolic requirements (Denno and Douglass 1986, Chown and Gaston 2010, Karban et al. 2012, Kaspari et al. 2017, Welti et al. 2019. Additionally, factors such as temperature are likely to influence plant (Rudgers et al. 2014, Fridley et al. 2016, Töpper et al. 2018 and herbivore (Robinet and Roques 2010, Boggs and Inouye 2012, Murray et al. 2013) population production and fitness at different rates and time scales. ...
Herbivory rates have classically been hypothesized to decrease from the tropics towards higher latitudes because the more benign abiotic conditions in tropical systems foster greater ecosystem complexity including greater intensity of biotic interactions. However, attempts to quantify latitudinal patterns of herbivory often fail to support this hypothesis. While biases have been offered as explanations for null results, here, we argue that framing the question of latitudinal variation in herbivory around nutrient and energetic constraints of insect herbivores and plants may provide mechanistic explanations of latitudinal herbivory patterns. As a case study, we focused on sodium as an uncoupled nutrient between herbivore and plant communities: sodium is a key limiting micronutrient for herbivore neural and muscular development while present at orders of magnitude lower concentrations in plants. We compared sodium deposition with latitude, mean annual temperature (MAT) and actual evapotranspiration (measure of primary productivity, AET) in their ability to predict consumed percentage leaf area from published datasets. Leaf percent herbivory increased with sodium deposition and MAT and decreased with latitude but was unrelated to AET. Sodium had comparable effect size and predictive ability to either MAT or latitude. Additionally, herbivory was highest in locales with both high sodium deposition and high MAT. Our hypothesis that geographic variation in herbivory is driven by an interaction of unrestrictive temperature environments (high MAT) and limiting nutrient supply to herbivores (high sodium deposition) was strongly supported. We propose that greater generality, predictability and theoretical development on geographic variation in herbivory will arise from a refocus on the biophysical constraints (e.g. productivity, micronutrient availability, leaf mass consumed) that ultimately control consumer interactions rather than latitude per se. This refocus is likely to open new hypotheses for the evolution of defense syndromes across plant populations and communities based on the specific geography of limiting nutrients.
... Hence, the proportion of vascular plant taxa discussed here that are very rare is comparable to that on a global scale 3 . A considerable unknown as the Arctic warms is whether tundra plant diversity will increase, presumably as a consequence of invasion by lower-latitude taxa 24 , or decrease, presumably as a consequence of increasing dominance by extant large-statured, resource-acquisitive taxa 14,25 . Nonetheless, warming-driven losses may ultimately outpace warming-driven gains in local plant diversity, especially in moisture-limited regions 26 such as the Kangerlussuaq study site 27 . ...
Ecological rarity, characterized by low abundance or limited distribution, is typical of most species, yet our understanding of what factors contribute to the persistence of rare species remains limited. Consequently, little is also known about whether rare species might respond differently than common species to direct (e.g., abiotic) and indirect (e.g., biotic) effects of climate change. We investigated the effects of warming and exclusion of large herbivores on 14 tundra taxa, three of which were common and 11 of which were rare, at an inland, low-arctic study site near Kangerlussuaq, Greenland. Across all taxa, pooled commonness was reduced by experimental warming, and more strongly under herbivore exclusion than under herbivory. However, taxon-specific analyses revealed that although warming elicited variable effects on commonness, herbivore exclusion disproportionately reduced the commonness of rare taxa. Over the 15-year duration of the experiment, we also observed trends in commonness and rarity under all treatments through time. Sitewide commonness increased for two common taxa, the deciduous shrubs Betula nana and Salix glauca, and declined in six other taxa, all of which were rare. Rates of increase or decline in commonness (i.e., temporal trends over the duration of the experiment) were strongly related to baseline commonness of taxa early in the experiment under all treatments except warming with grazing. Hence, commonness itself may be a strong predictor of species’ responses to climate change in the arctic tundra biome, but large herbivores may mediate such responses in rare taxa, perhaps facilitating their persistence.
... We expected the following: (1) Given that resource-acquisitive traits can be detrimental when resources are limiting, and advantageous when not, (Fridley et al. 2016;Zhang et al. 2020), species with resourceacquisitive traits should be most responsive to the manipulations (either suffering e.g. due to water shortage or benefiting e.g. from a longer growing season). ...
Understanding the traits mediating species’ responses to climate change is a cornerstone for predicting future community composition and ecosystem function. Although species’ eco-physiological properties determine their response to environmental change, most trait-based studies focus on a small subset of easily-measured morphological traits as proxies for physiology. This choice may limit our ability to predict the impacts of climate change on species’ demography, and obscure the underlying mechanisms. We conducted a transplantation experiment along a 1000 m Alpine elevation gradient to quantify the degree to which plant demographic responses to climate were predicted by eco-physiological performance versus common morphological traits. Although physiological measurements revealed that warming favored species with a conservative water use strategy, the predictive power of physiological traits did not exceed that of morphological traits. Our results show that while easily-measured morphological traits can successfully predict demographic responses to climate, eco-physiological approaches are needed to understand mechanism.
... The mechanism of growing time shift to avoid VPD stress might be more reasonable. Although it is difficult to prove this point at diurnal scale, large temporal scale (seasonal) studies may reflect this mechanism that find increases in productivity of grass ecosystems despite increasing aridity, by earlier spring emergence and delay autumn senescence (Fridley et al., 2016;Hufkens et al., 2016). However, more plant physiology related research is needed. ...
Increasing vapor pressure deficit (VPD) has led to widespread reductions in vegetation carbon uptake by stomatal hydraulic regulation. The response of vegetation to VPD is therefore paramount in the global water and carbon cycle, and draws worldwide attention. However, the hysteretic response of ecosystem water consumption to VPD, although widely reported across the world, is still lack of systematic and consistent research on its global patterns and ecological implications. Based on a newly developed hourly dataset of land-atmosphere fluxes, this study finds that hysteresis increases with climatic aridity and long hysteresis mainly occurs in water-limited areas; the hysteretic response of water consumption to VPD for woody ecosystems is shorter than that for the herbaceous ecosystems; interestingly, gross primary productivity (GPP) increases with hysteresis at the high hysteresis ends in dry environments (dry-humid, semi-arid and arid zones), which might suggest an existence of drought-adapting mechanisms of vegetation growth that is relevant to hysteresis but overlooked before. This study provides important information for projecting future shifts of ecosystem functions under increasing atmospheric dry stress.
... From the available set of macroclimate variables, we selected the two that best address the effects of an ongoing climate warming on vegetation: the length and temperature of the growing season (Fridley et al., 2016) and the minimum winter temperature, which is particularly significant to fen communities (Horsáková et al., 2018;Küttim et al., 2019). To address the length of the growing season, we calculated the effective temperature sum (growing degree days) at the baseline of 5°C (GDD5). ...
Rising temperatures may endanger fragile ecosystems because their character and key species show different habitat affinities under different climates. This assumption has only been tested in limited geographical scales. In fens, one of the most endangered ecosystems in Europe, broader pH niches have been reported from cold areas and are expected for colder past periods. We used the largest European‐scale vegetation database from fens to test the hypothesis that pH interacts with macroclimate temperature in forming realised niches of fen moss and vascular plant species. We calibrated the data set (29,885 plots after heterogeneity‐constrained resampling) with temperature, using two macroclimate variables, and with the adjusted pH, a variable combining pH and calcium richness. We modelled temperature, pH, and water level niches for one hundred species best characterising European fens using Generalised Additive Models and tested the interaction between pH and temperature. Fifty‐five fen species showed a statistically significant interaction between pH and temperature (adjP˂0.01). Forty‐six of them (84%) showed a positive interaction manifested by a shift or restriction of their niche to higher pH in warmer locations. Nine vascular plants and no moss showed the opposite interaction. Mosses showed significantly greater interaction. We conclude that climate significantly modulates edaphic niches of fen plants, especially bryophytes. This result explains previously reported regional changes in realised pH niches, a current habitat‐dependent decline of endangered taxa, and distribution changes in the past. A warmer climate makes growing seasons longer and warmer, increases productivity, and may lower the water level. These effects prolong the duration and intensity of interspecific competition, support highly competitive Sphagnum mosses, and, as such, force niches of specialised fen species towards narrower high‐pH ranges. Recent anthropogenic landscape changes pose a severe threat to many fen species and call for mitigation measures to lower competition pressure in their refugia.
... Hence, the proportion of vascular plant taxa discussed here that are very rare is comparable to that on a global scale 2 . A considerable unknown as the Arctic warms is whether tundra plant diversity will increase, presumably as a consequence of invasion by lower-latitude taxa 22 , or decrease, presumably as a consequence of increasing dominance by extant large-statured, resource-acquisitive taxa 12,23 . Nonetheless, warming-driven losses may ultimately outpace warmingdriven gains in local plant diversity, especially in moisture-limited regions 24 such as the Kangerlussuaq study site 25 . ...
While most species are rare, our understanding of how rare species persist remains limited. Consequently, little is also known about how the commonness and rarity of co-occurring species might be differentially impacted by direct and indirect effects of climate change. We report results of a 15-year field experiment investigating effects on commonness and rarity of 14 arctic tundra plant taxa to warming and exclusion of large herbivores, factors demonstrated to have important effects on plant community composition in many biomes. Across all taxa, pooled commonness was reduced by experimental warming, and more strongly under herbivore exclusion than under herbivory. However, taxon-specific analyses revealed that although warming elicited variable effects on commonness, herbivore exclusion disproportionately reduced the commonness of rare taxa. Over the course of the experiment, we also observed trends in commonness and rarity under all treatments through time. Sitewide commonness increased for two common taxa, the deciduous shrubs Betula nana and Salix glauca, and declined in six other taxa, all of which were rare. Across experimental treatments, rates of increase and decline in commonness (i.e., temporal trends over the duration of the experiment) were strongly related to baseline commonness of taxa early in the experiment. Hence, commonness itself may be a strong predictor of plant species responses to climate change in the arctic tundra biome, but large herbivores may mediate such responses in rare taxa, perhaps facilitating their persistence.
... Understanding the causes of species' range limits has become more important as climate change causes species ranges to shift (Gottfried et al., 2012;Kelly & Goulden, 2008;Lenoir et al., 2008;Parmesan, 2006). Climate change can cause population declines via physiological stress (Angert et al., 2013;Fridley et al., 2016;Tylianakis et al., 2008). Less studied is how range shifts associated with climate change create novel communities as species from previously disparate geographical locales come into contact (Alexander et al., 2016). ...
Although rarely experimentally tested, biotic interactions have long been hypothesised to limit low‐elevation range boundaries of species. We tested the effects of herbivory on three alpine‐restricted plant species by transplanting plants below (novel), at the edge (limit), or in the centre (core) of their current elevational range and factorially fencing‐out above‐ and belowground mammals. Herbivore damage was greater in range limit and novel habitats than in range cores. Exclosures increased plant biomass and reproduction more in novel habitats than in range cores, suggesting demographic costs of novel interactions with herbivores. We then used demographic models to project population growth rates, which increased 5–20% more under herbivore exclosure at range limit and novel sites than in core habitats. Our results identify mammalian herbivores as key drivers of the low‐elevation range limits of alpine plants and indicate that upward encroachment of herbivores could trigger local extinctions by depressing plant population growth. Although rarely experimentally tested, biotic interactions have long been hypothesized to limit low‐elevation range boundaries of species. We tested the effects of herbivory on three alpine‐restricted plant species by transplanting plants below (novel), at the edge (limit), or in the center (core) of their current elevational range and factorially fencing‐out above‐ and belowground mammals. Our results identify mammalian herbivores as key drivers of the low‐elevation range limits of alpine plants and indicate that upward encroachment of herbivores could trigger local extinctions by depressing plant population growth.
... Nonetheless, it remains necessary to advance research into distinguishing the regional climatic determinants and the response mechanisms of vegetation dynamics and their corresponding spatial pattern on a macroscopic scale [19]. Further, the superimposition of multiple climatic factors compounds the uncertainty in the investigation of their relationships with vegetation growth and cover [20]. In this context, based on the eco-geographical regionalization of the Tibetan Plateau, this study analyzed the spatial nonstationary relationships of NDVI vis-à-vis various climatic factors and their respective variability over a recent time period (at least 30 years), by using such methods as geographically weighted regression (GWR), with two objectives in mind. ...
Climate change has significantly affected the ecosystem of the Tibetan Plateau. There, temperature rises and altered precipitation patterns have led to notable changes in its vegetation growth processes and vegetation cover features. Yet current research still pays relatively little attention to the regional climatic determinants and response patterns of such vegetation dynamics. In this study, spatial patterns in the response of the normalized difference vegetation index (NDVI) to climate change and its dynamic characteristics during the growing season were examined for the Tibetan Plateau, by using a pixel-scale-based geographically weighted regression (GWR) based on the Global Inventory Modeling and Mapping Studies (GIMMS) NDVI data, as well as data for temperature and moisture indices collected at meteorological stations, for the period 1982–2015. The results show the following. Spatial nonstationary relationships, primarily positive, were found between the NDVI and climatic factors in the Tibetan Plateau. However, warming adversely affected vegetation growth and cover in some arid and semiarid regions of the northeast and west Tibetan Plateau. Additionally, precipitation played a dominant role in the NDVI of the Tibetan Plateau in the largest area (accounting for 39.7% of total area). This suggests that increased moisture conditions considerably facilitated vegetation growth and cover in these regions during the study period. Temperature mainly played a dominant role in the NDVI in some parts of the plateau sub-cold zone and some southeastern regions of the Tibetan Plateau. In particular, the minimum temperature was the dominant driver of NDVI over a larger area than any of the other temperature indices. Furthermore, spatial regressions between NDVI dynamics and climatic variability revealed that a faster warming rate in the arid and semiarid regions impeded vegetation growth through mechanisms such as drought intensification. Moisture variability was found to act as a key factor regulating the extent of vegetation cover on the south Tibetan Plateau.
... Also, the grassland biome is the largest in the world and grassland productivity are highly sensitive to climate variability (Hovenden et al., 2014). Grassland productivity has been found to be increasing under warmer mean annual temperatures (Fridley et al., 2016;Hufkens et al., 2016). Considering the high underestimation of grassland GPP by models with biome-specific temperature parameters, grassland could actually have performed larger variability if we use GPP estimated using site-specific parameters. ...
Gross primary productivity (GPP) of vegetation is affected by air temperature. Biogeochemical models use the optimum air temperature (T opt) parameter, which comes from biome-specific look-up tables (T opt− b− LT). Many studies have shown that plants have the capacity to adapt to changes in environmental conditions over time, which suggests that the static T opt− b− LT parameters in the biogeochemical models may poorly represent actual T opt and induce uncertainty in GPP estimates. Here, we estimated biome-specific, site-year-specific, and site-specific optimum air temperature using GPP data from eddy covariance (EC) flux tower sites (GPP EC) (T opt− b− EC , T opt− sy− EC , T opt− s− EC), the Enhanced Vegetation Index (EVI) from MODIS images (T opt− b− EVI , T opt− sy− EVI , T opt− s− EVI), and mean daytime air temperature (T DT). We evaluated the consistency among the four T opt parameters (T opt− b , T opt− sy , T opt− s and T opt− b− LT), and assessed how they affect satellite-based GPP estimates. We find that T opt parameters from MODIS EVI agree well with those from GPP EC , which indicates that EVI can be used as a variable to estimate T opt at individual pixels over large spatial domains. T opt− b , T opt− sy , and T opt− s differed significantly from T opt− b− LT. GPP estimates using T opt− b and T opt− sy were more consistent with GPP EC than when using T opt− b− LT for all the land cover types. Our use of T opt− sy substantially improved 8-day and annual GPP estimates across biomess (from 1% to 34%), especially for cropland, grassland, and open shrubland. Our simple calculation shows that global GPP estimates differ by up to 10 Pg C/yr when using our suggested T opt− sy− EVI instead of using the static T opt− b− LT. Our new approach on estimating T opt has the potential to improve estimates of GPP from satellite-based models, which could lead to better understanding of carbon-climate interactions.
... Previous studies, based on data from satellite remote sensing and in situ observations, have reported that vegetation in the mid-high latitudes of the northern hemisphere generally shows a trend of earlier green-up onset and delayed senescence but with complex spatiotemporal patterns [5,6]. As a result, a phenologically induced extension of the growing season has been considered a key factor in the long-term variability of vegetation production [7,8]. Climate attribution analyses confirm that changes in vegetation phenology in the northern mid-high latitudes are mainly controlled by the interannual variation of air temperature, but, in arid and semi-arid areas, vegetation phenology is more significantly affected by temporal and spatial patterns of precipitate [9,10]. ...
Global climate change has led to significant changes in seasonal rhythm events of vegetation growth, such as spring onset and autumn senescence. Spatiotemporal shifts in these vegetation phenological metrics have been widely reported over the globe. Vegetation growth peak represents plant photosynthesis capacity and responds to climate change. At present, spatiotemporal changes in vegetation growth peak characteristics (timing and maximum growth magnitude) and their underlying governing mechanisms remain unclear at regional scales. In this study, the spatiotemporal dynamics of vegetation growth peak in northeast China (NEC) was investigated using long-term NDVI time series. Then, the effects of climatic factors and spring phenology on vegetation growth peak were examined. Finally, the contribution of growth peak to vegetation production variability was estimated. The results of the phenological analysis indicate that the date of vegetation green up in spring and growth peak in summer generally present a delayed trend, while the amplitude of growth peak shows an increasing trend. There is an underlying cycle of 11 years in the vegetation growth peak of the entire study area. Air temperature and precipitation before the growing season have a small impact on vegetation growth peak amplitude both in its spatial extent and magnitude (mainly over grasslands) but have a significant influence on the date of the growth peak in the forests of the northern area. Spring green-up onset has a more significant impact on growth peak than air temperature and precipitation. Although green-up date plays a more pronounced role in controlling the amplitude of the growth peak in forests and grasslands, it also affects the date of growth peak in croplands. The amplitude of the growth peak has a significant effect on the inter-annual variability of vegetation production. The discrepant patterns of growth peak response to climate and phenology reflect the distinct adaptability of the vegetation growth peak to climate change, and result in different carbon sink patterns over the study area. The study of growth peak could improve our understanding of vegetation photosynthesis activity over various land covers and its contribution to carbon uptake.
... Grassland phenology is highly sensitive to climatic changes (Henebry, 2013). Previous studies have reported a shift in spring phenology in temperate grasslands that subsequently affected plant productivity, species distribution and feedbacks to climate systems (Chuine et al., 2000;Fridley et al., 2016;Peñuelas et al., 2009;Piao et al., 2019). Changes in grassland phenology have been associated with the climate warming observed over the last four decades (Hu et al., 2015;Jeong et al., 2011). ...
Aim
Vegetation phenology is highly sensitive to climate change. The timing of spring phenology in temperate grasslands is regulated primarily by temperature and precipitation. The aim of this study was to determine whether the primary factor regulating vegetation phenology has changed under ongoing climate change and the underlying mechanisms.
Location
Temperate semi‐dry grasslands in China.
Time period
1982–2015.
Major taxa studied
Temperate grassland.
Methods
We extracted start of season (SOS) dates using five standard methods from satellite‐derived normalized difference vegetation index (NDVI) data and determined the primary factor regulating spring phenology using partial correlation analysis.
Results
The SOS date did not change significantly during the entire 1982–2015 study period in these semi‐dry grasslands, but interannual variability increased significantly from the first subperiod [1982–1998, 8.8 ± 1.1 days (mean ± SE)] to the second subperiod (1999–2015, 10.3 ± 1.1 days). Interestingly, we found that the primary factor regulating SOS shifted from precipitation during 1982–1998 to temperature during 1999–2015. Specifically, we found that during the first period, the SOS in 67.5% of the study area was determined by precipitation (mean partial correlation coefficient, r = 0.58 ± 0.16), but during the second period the main regulating factor in 75.0% of the study area was temperature (r = 0.61 ± 0.14).
Main conclusions
The change in the primary driver of spring phenology was attributed mainly to significant increases in preseason precipitation. Our study highlights that the response of spring phenology to climatic factors might change under ongoing climate change. This shift should be addressed in phenology models to simulate grassland phenology better, in addition to its impact on carbon and water cycles in future climate conditions.
... The functional traits of the plant are studied progressively as a basic framework to comprehend species response towards ecological changes and differences in their distribution [22,23]. They deliver a better understanding of concurrent changes in desert areas, nutrient accessibility that differentially affects co-occurring desert plant species and convergent evolution [24,25]. It has been found that these traits strongly correlate with soil moisture contents [26] and also play a key role in finding competitive hierarchies among different plant species [23]. ...
Convergence is commonly caused by environmental filtering, severe climatic conditions and local disturbance. The basic aim of the present study was to understand the pattern of leaf traits
across diverse desert plant species in a common garden, in addition to determining the e�ect of plant life forms (PLF), such as herb, shrub and subshrub, phylogeny and soil properties on leaf traits.
Six leaf traits, namely carbon (C), nitrogen (N), phosphorus (P), potassium (K), �13C and leaf water potential (LWP) of 37 dominant desert plant species were investigated and analyzed. The C, N, K
and �13C concentrations in leaves of shrubs were found higher than herbs and subshrubs; however, P and LWP levels were higher in the leaves of subshrubs following herbs and shrubs. Moreover,
leaf C showed a significant positive correlation with N and a negative correlation with �13C. Leaf N exhibited a positive correlation with P. The relationship between soil and plant macro-elements was
found generally insignificant but soil C and N exhibited a significant positive correlation with leaf P. Taxonomy showed a stronger e�ect on leaf C, N, P and �13C than soil properties, explaining >50% of
the total variability. C3 plants showed higher leaf C, N, P, K and LWP concentration than C4 plants, whereas C4 plants had higher �
3C than C3 plants. Legumes exhibited higher leaf C, N, K and LWP
than nonlegumes, while nonlegumes had higher P and �
13C concentration than legumes. In all the species, significant phylogenetic signals (PS) were detected for C and N and nonsignificant PS for the rest of the leaf traits. In addition, these phylogenetic signals were found lower (K-value < 1),
and the maximum K-value was noted for C (K = 0.35). The plants of common garden evolved and adapted themselves for their survival in the arid environment and showed convergent variations in
their leaf traits. However, these variations were not phylogenetics-specific. Furthermore, marks of convergence found in leaf traits of the study area were most likely due to the environmental factors.
Keywords: convergence; leaf traits; desert plants; phylogenetic signals
... Climate change is projected to result in an increase in yield for temperate grasslands (Abdalla et al., 2010;Shrestha et al., 2015), although the length of the grazing period may decline for western Britain (Phelan et al., 2015). The impact on the seasonality of production is affected by complex interactions between the botanical composition of the sward and its cutting / grazing management (Bloor et al., 2010;Bloch et al., 2015) and the degree of warming and changes in precipitation (Fridley et al., 2016). In addition, increases in CO 2 and changes in climate may affect the digestibility of the sward (AbdElgawad et al., 2014;Lee et al., 2017;Dellar et al., 2018)) which will impact on the dry matter intake of the grazing animal and hence productivity. ...
Agriculture is a vital economic sector, providing food, fibre, and energy to a growing human population. Livestock are an important part of this sector, however the evidence and understanding of how a changing climate may affect livestock production systems, or how they may adapt to the changes, is a neglected area compared to the research into crop production. In this paper, we focus on livestock in the United Kingdom (UK), as an example of a temperate region likely to experience at least moderate changes in climate that will require changes to the way agricultural systems operate. We summarise the projected climate changes in this region, identify the main impacts likely to affect livestock agriculture, and discuss potential adaptation options at the farm level. We also categorise the adaptation options by the types of costs they incur, emphasising that many of these options involve management changes rather than investment and therefore no financial cost. Finally, we discuss the need for longer term planning to prepare for changes that have not yet been observed.
... Myers-Smith et al., 2011), as non-woody species of the habitat-specific pool are lost. This structural change is expectedto increase productivity(Fridley, Lynn, Grime, & Askew, 2016), affect the atmospheric and soil CO 2 content(Zhang et al., 2013), ...
Aim
Biogeographical processes and past environmental conditions are known to constrain current patterns of species, functional and phylogenetic diversity. An unanswered question is whether such constraints to biodiversity also affect ecosystem processes.
Location
Global.
Time period
Neogene and Quaternary.
Major taxa studied
Vascular plants.
Methods
We propose that evolution, migration‐lag in response to environmental changes, and extinction may result in historical legacies in current ecosystem composition (species and functional) that can lead to historical legacies in ecosystem processes – that is, deviations from the potential rates or magnitudes of ecosystem processes, given current environmental conditions and the habitat‐suitable native species and trait pools that exist under such circumstances.
Results
Historical legacies in ecosystem processes may begin with changes in species richness and composition in response to environmental shifts. These changes are mediated by response traits that determine how species react to environmental changes and track suitable environmental conditions. Response traits are often associated with effect traits, which determine the rates and magnitude of ecosystem processes. Via this association, environmentally driven response‐trait determined changes in species diversity may cascade to ecosystem processes through effect trait compositional changes. These changes could lead to ecosystem processes deviating from a potential state defined by current environmental conditions and the overall species pool. We populate this conceptual framework with cases that show how historical legacies in biodiversity translate to historical legacies in ecosystem processes, and we discuss the implications of the concept for global change ecology.
Main conclusions
We need to rethink our expectations of future ecological dynamics as past, and current, environmental changes may push ecosystem processes away from their environmentally and compositionally defined potential state.
... Multiple factors associated with seasonal changes (i.e. temperature and moisture) can affect plant productivity and N dynamics (Agehara & Warncke 2005;Xu & Zhou 2006;Fridley, Lynn, Grime, & Askew 2016). Consequently, studies on NUE can have a seasonal component. ...
Grassland management intensification can greatly influence nitrogen (N) dynamics between aboveground and belowground compartments mainly because of the large amount of available N forms, which are repeatedly added to soils. A better understanding of how chronic fertilisation might affect N use efficiency (NUE) in plants can contribute to reducing N losses from soils and improve the sustainability of managed grasslands. Here we address how NUE might be affected by (1) the addition of key nutrients (e.g. N, P, K, Mg) in different combinations, (2) grazing by rabbits, and (3) liming (i.e. CaCO3 applications) in a 22-year-old permanent grassland experiment established in Berkshire, UK, in 1991. We first calculate seven different NUE indexes, which are known to respond either to changes in soil N availability (i.e. endogenous N inputs from soil N mineralization processes) or to exogenous N inputs (i.e. synthetic N fertiliser). We found that plant NUE calculated as plant biomass produced per unit of N acquired significantly decreased under the chronic addition of multiple nutrients (NPKMg) and was even lower under N-only applications. Most NUE indexes significantly decreased under grazing but greatly increased under liming applications. We found evidence that NUE indexes, which accounted for endogenous N sources decreased at increased rates of soil N mineralization. Finally, we found no significant relationships between any of the NUE indexes and estimates of soil N losses (Mg N ha⁻¹) or N retention in soils (i.e. units of soil N retained per unit of N added) calculated from changes in net soil N budget over 22 years. Our study carried out on relatively acidic sandy soils suggests how liming applications in combination with low levels of multi-nutrient additions (NPKMg) can significantly improve plant biomass production per unit of N added thus contributing to enhance the sustainability of managed grassland ecosystems.
... However, at fine spatial scales there has been significant reorganization of community structure, associated with centimetre-scale edaphic variation that locally modifies the effects of the climate treatments (Fridley, Grime, Askew, Moser, & Stevens, 2011). Subsequently, community change has been characterized by gradual change in species abundance, underpinned by differences in species' functional traits (Fridley, Lynn, Grime, & Askew, 2016). Evolution may be one of the mechanisms limiting climate-driven change in grassland community structure at BCCIL (Grime et al., 2008). ...
Reproductive and early‐acting life‐history traits are likely to be particularly important determinants of plant fitness under a changing climate. There have, however, been few robust tests of the evolution of these traits under chronic climate change in natural ecosystems. Such studies are urgently needed, to evaluate the contribution of evolutionary change to population persistence.
Here, we examine climate‐driven evolutionary change in reproductive and early‐acting plant life‐history traits in the long‐lived perennial plant, Festuca ovina .
We collected established plants of F. ovina from species‐rich calcareous grassland at the Buxton Climate Change Impacts Laboratory (BCCIL), after 17 years of in situ experimental drought treatment.
P1 plants collected from drought‐treated and control (ambient climate) plots at BCCIL were used to create an open‐pollinated F1 progeny array, which was subsequently validated using microsatellite markers to establish a robust bi‐parental pedigree. We measured the timing of germination and seed mass in the F1 progeny, the P1 paternal contribution to F1 offspring (paternal reproductive success), and assessed the effects of flowering time on the mating system.
F1 seed with ancestry in drought‐treated plots at BCCIL germinated significantly later than seed derived from individuals from control plots. P1 plants from the drought treatment flowered significantly earlier than those from the control plots in summer 2012, but not in 2013. Male reproductive success was also lower in P1 plants collected from drought plots than those from control plots. Furthermore, our pedigree revealed that mating among parents of the F1 progeny had been assortative with respect to flowering time.
Synthesis . Our study shows that chronic drought treatment at Buxton Climate Change Impacts Laboratory has driven rapid evolutionary change in reproductive and early‐acting life‐history traits in Festuca ovina , and suggests that evolutionary differentiation may be reinforced through changes in flowering time that reduce the potential for gene flow.
... Microbes associated with resource-acquisitive plant trait strategies (i.e., taller, thinner leaves) may benefit plants if climate warming increases the importance of plant competition (Fridley et al. 2016). Evidence for microbially driven intraspecific variation in plant traits is mixed (reviewed by Friesen et al. 2011). ...
Climate change is causing species with non-overlapping ranges to come in contact, and a key challenge is to predict the consequences of such species re-shuffling. Experiments on plants have focused largely on novel competitive interactions; other species interactions, such as plant–microbe symbioses, while less studied, may also influence plant responses to climate change. In this greenhouse study, we evaluated interactions between soil microbes and alpine-restricted plant species, simulating a warming scenario in which low-elevation microbes migrate upslope into the distribution of alpine plants. We examined three alpine grasses from the Rocky Mountains, CO, USA (Poa alpina, Festuca brachyphylla, and Elymus scribneri). We used soil inocula from within (resident) or below (novel) the plants’ current elevation range and examined responses in plant biomass, plant traits, and fungal colonization of roots. Resident soil inocula from the species’ home range decreased biomass to a greater extent than novel soil inocula. The depressed growth in resident soils suggested that these soils harbor more carbon-demanding microbes, as plant biomass generally declined with greater fungal colonization of roots, especially in resident soil inocula. Although plant traits did not respond to the provenance of soil inocula, specific leaf area declined and root:shoot ratio increased when soil inocula were sterilized, indicating microbial mediation of plant trait expression. Contrary to current predictions, our findings suggest that if upwardly migrating microbes were to displace current soil microbes, alpine plants may benefit from this warming-induced microbial re-shuffling.
... Moreover, since the plants could not grow with temperature fall during the cold seasons (until late March), their growth period was limited to the interval between 21 March and the first week of June (Fig. 6). These factors decreased NPP in semi-arid regions (Fridley et al., 2016). Low temperatures and delayed plant phenological stages at highlands reduced NPP values in the early growing season (Fig. 6). ...
Net primary production (NPP) is an indicator of rangeland ecosystem function. This research assessed the potential of the Carnegie Ames Stanford Approach (CASA) model for estimating NPP and its spatial and temporal changes in semi-arid rangelands of Semirom County, Iran. Using CASA model, we estimated the NPP values based on monthly climate data and the normalized difference vegetation index (NDVI) obtained from the MODIS sensor. Regression analysis was then applied to compare the estimated production data with observed production data. The spatial and temporal changes in NPP and light utilization efficiency (LUE) were investigated in different rangeland vegetation types. The standardized precipitation index (SPI) was also calculated at different time scales and the correlation of SPI with NPP changes was determined. The results indicated that the estimated NPP values varied from 0.00 to 74.48 g C/(m2·a). The observed and estimated NPP values had different correlations, depending on rangeland conditions and vegetation types. The highest and lowest correlations were respectively observed in Astragalus spp.-Agropyron spp. rangeland (R2=0.75) with good condition and Gundelia spp.-Cousinia spp. rangeland (R2=0.36) with poor and very poor conditions. The maximum and minimum LUE values were found in Astragalus spp.-Agropyron spp. rangeland (0.117 g C/MJ) with good condition and annual grasses-annual forbs rangeland (0.010 g C/MJ), respectively. According to the correlations between SPI and NPP changes, the effects of drought periods on NPP depended on vegetation types and rangeland conditions. Annual plants had the highest drought sensitivity while shrubs exhibited the lowest drought sensitivity. The positive effects of wet periods on NPP were less evident in degraded areas where the destructive effects of drought were more prominent. Therefore, determining vegetation types and rangeland conditions is essential in NPP estimation. The findings of this study confirmed the potential of the CASA for estimating rangeland production. Therefore, the model output maps can be used to evaluate, monitor and optimize rangeland management in semi-arid rangelands of Iran where MODIS NPP products are not available.
... Grasslands constitute more than 30% of the global land surface and is recognized as a key component of the terrestrial ecosystems (Hufkens et al., 2016). On an ecosystem scale, phenology (i.e., the timing of recurrent biological cycles) is one of the primary controls on plant productivity and species distribution (Fridley et al., 2016;Xia et al., 2015), thereby further regulating the terrestrial biogeochemical cycles (Forrest & Miller-Rushing, 2010). Changes in plant phenology have been widely reported to connect with variations in climatic conditions (Barichivich et al., 2013;Piao et al., 2015). ...
Plain Language Summary
The start and end of the plant growing season are changing in response to global warming, which has been widely reported by existing literatures using mainly Earth system modeling and remote sensing approaches. There is less direct evidence from the ground observations to demonstrate the effect of climate warming on the changes in plant phenology. In this study, we collated and analyzed the temporal changes in both climates and plant phenologies (e.g., the start and end of plant growing season) at eight long‐term experimental sites across the Inner Mongolian grasslands. These experiments have lasted for more than 30 years and are distributed across a vast area representing all the main vegetation types at the regional scale. We found that an overall climate warming took place during the study period of 1982–2012. However, two thirds of the observed plant phenologies for different species across the eight sites did not show significant change. In general, plant phenology exhibited divergent shifts in magnitudes and directions. Apart from climate changes, the day length could also coregulate the changes in the requirement of accumulated temperature and thus the length of growing season for some species such as L. chinensis.
Perhaps as much as any other scientist in the 20th century, J.P. Grime transformed the study of plant ecology and helped shepherd the field toward international prominence as a nexus of ideas related to global environmental change. Editors at the Journal of Ecology asked a group of senior plant ecologists to comment on Grime's scientific legacy.
This commentary piece includes individual responses of 14 scientists from around the world attesting to Grime's foundational role in plant functional ecology, including his knack for sparking controversy, his unique approach to theory formulation involving clever experiments and standardized trait measurements of large numbers of species, and the continued impact of his work on ecological science and policy.
Altered climate, nutrient enrichment and changes in grazing patterns are important environmental and biotic changes in temperate grassland systems. Singly and in concert these factors can influence plant performance and traits, with consequences for species competitive ability, and thus for species coexistence, community composition and diversity. However, we lack experimental tests of the mechanisms, such as competition for light, driving plant performance and traits under nutrient enrichment, grazer exclusion and future climate. We used transplants of Silene latifolia, a widespread grassland forb in Europe, to study plant responses to interactions among climate, nutrients, grazing and light. We recorded transplant biomass, height, specific leaf area (SLA) and foliar carbon to nitrogen ratio (C:N) in full-factorial combinations of future climate treatment, fertilization, grazer exclusion and light addition via LED-lamps. Future climate and fertilization together increased transplant height but only in unlighted plots. Light addition increased SLA in ambient climate, and decreased C:N in unfertilized plots. Further, transplants had higher biomass in future climatic conditions when protected from grazers. In general, grazing had a strong negative effect on all measured variables regardless of added nutrients and light. Our results show that competition for light may lead to taller individuals and interacts with climate and nutrients to affect traits related to resource-use. Furthermore, our study suggests grazing may counteract the benefits of future climate on the biomass of species such as Silene latifolia. Consequently, grazers and light may be important modulators of individual plant performance and traits under nutrient enrichment and future climatic conditions.
Anthropogenic warming and land‐use change are expected to accelerate global soil organic carbon (SOC) losses and change plant species composition and richness. However, how changes in plant composition and species richness mediate SOC responses to climate warming and land‐use change remains poorly understood. Using data from a 7‐year warming and clipping field experiment in an alpine meadow on the Qinghai‐Tibetan Plateau, we examined the direct effects of warming and clipping on SOC storage versus their indirect effects mediated by plant functional type and species richness. We found that warming significantly increased SOC storage by 8.1% and clipping decreased it by 6.4%, which was closely correlated with the corresponding response of below‐ground net primary productivity (BNPP). We also found a negative correlation between SOC storage and species richness, which was ascribed to the increased BNPP via enhancing the dominance of grasses and decreasing species richness under warming. The lower SOC storage under clipping was caused by the clipping‐induced decrease in BNPP via weakening the dominance of grasses and increasing species richness. Our findings highlight that the SOC storage in this alpine meadow under climate warming and clipping was primarily governed by BNPP changes, which was mediated by changes in the dominance of grasses and species richness. Overall, our study demonstrates that shifting to the dominance of grasses and changing species richness would benefit soil C sequestration under climate warming, but this positive effect would be dampened by grazing or hay harvest.
Inner Mongolia grassland is a sensitive area of vegetation response to climate change in China and an ecologically fragile area of terrestrial ecosystem, which is easily degraded due to the coordinated interference of natural and human factors. Therefore, it is of great practical significance to explore the spatial-temporal variation of vegetation coverage and the influence of hydrothermal conditions on its growth, to protect the regional ecological environment, to realize the sustainable development of animal husbandry and to make more reasonable and effective use of grassland resources in Inner Mongolia. In this study, linear regression, partial correlation analysis and Copula method were used to investigate the spatial patterns of NDVI internal variability and its relationship with climate change in various regions of Inner Mongolia from 1982-2020, and the results are as follows:(1) From 1982 to 2020, the surface vegetation coverage in Inner Mongolia showed an increasing trend, and the main climatic factors affecting vegetation growth in Inner Mongolia were different. In the eastern and central parts of the study area, vegetation growth is highly dependent on precipitation, while in the western part of the study area, vegetation growth is greatly affected by climate and precipitation. (2) When the temperature and precipitation of vegetation growth exceed a certain threshold, the probability of plant growth inhibition is higher. (3) NDVI variation trends of different vegetation types are also different. The meadow vegetation degraded obviously, while the marsh vegetation and desert vegetation increased obviously. (4) In addition to climate influences such as temperature and rainfall, livestock numbers and human population are the main forms of human activities accelerating grassland degradation. The results of this study can help us understand the appropriate range or types of environmental factors affecting vegetation growth in Inner Mongolia, and on this basis, we can take appropriate interventions to effectively mitigate the impact of environmental change on vegetation.
Data availability
The NDVI3g datasets are acquired from https://ecocast.arc.nasa.gov/data/pub/gimms/. The CRU datasets are acquired from https://crudata.uea.ac.uk/cru/data/hrg/. The vegetation types datasets are acquired from https://www.resdc.cn/. The MOD13A2 datasets are acquired from http://landsweb.modaps.eosdis.nasa.gov/search.
John Philip ‘Phil’ Grime developed fundamental theory in plant ecology that emerged from a lifetime of fieldwork and experimental studies in the Sheffield region, South Yorkshire, UK. His approach was an unusual combination of observation, experiment and theory: he conducted detailed, intensive observations of natural communities, alongside experimental manipulation of those communities and simulated ‘microcosms’ in the service of formulating general rules (‘strategies’) by which plants evolve with respect to their environment. In this way, Grime was one of several key figures that propelled plant ecology away from descriptive methods focusing on vegetation composition and toward a science more integrated with other fields, including evolutionary biology and Earth science. Grime's investigative approach was an inspiration for the modern field of global change biology, and, by focusing on understanding the contrasting roles species and their traits play in the functioning of ecosystems, marked the beginning of the field of plant functional ecology. For much of his career Grime held the post of full professor (and in retirement, emeritus professor of ecology) at the University of Sheffield, where he also served as the director of the Unit of Comparative Plant Ecology and of the Buxton Climate Change Impacts Laboratory. Awarded an honorary doctorate by Radboud University (Nijmegen, The Netherlands) and a foreign membership of the Royal Netherlands Academy of Arts and Sciences, Grime was the first person awarded the Alexander von Humboldt Award of the International Association for Vegetation Science.
The productivity of permanent temperate cut grasslands is mainly driven by weather, soil characteristics, botanical composition and management. To adapt management to climate change, adjusting the cutting dates to reflect earlier onset of growth and expansion of the vegetation period is particularly important. Simulations of cut grassland productivity under climate change scenarios demands management settings to be dynamically derived from actual plant development rather than using static values derived from current management operations. This is even more important in the alpine region, where the predicted temperature increase is twice as high as compared to the global or Northern Hemispheric average.
For this purpose, we developed a dynamic management module that provides timing of cutting and manuring events when running the biogeochemical model LandscapeDNDC. We derived the dynamic management rules from long-term harvest measurements and monitoring data collected at pre-alpine grassland sites located in S-Germany and belonging to the TERENO monitoring network. We applied the management module for simulations of two grassland sites covering the period 2011–2100 and driven by scenarios that reflect the two representative concentration pathways (RCP) 4.5 and 8.5 and evaluated yield developments of different management regimes.
The management module was able to represent timing of current management operations in high agreement with several years of field observations (r² > 0.88). Even more, the shift of the first cutting dates scaled to a +1 °C temperature increase simulated with the climate change scenarios (−9.1 to −17.1 days) compared well to the shift recorded by the German Weather Service (DWD) in the study area from 1991−2016 (−9.4 to −14.0 days). In total, the shift in cutting dates and expansion of the growing season resulted in 1−2 additional cuts per year until 2100. Thereby, climate change increased yields of up to 6 % and 15 % in the RCP 4.5 and 8.5 scenarios with highest increases mainly found for dynamically adapted grassland management going along with increasing fertilization rates. In contrast, no or only minor yield increases were associated with simulations restricted to fertilization rates of 170 kg N ha−1 yr−1 as required by national legislations. Our study also shows that yields significantly decreased in drought years, when soil moisture is limiting plant growth but due to comparable high precipitation and water holding capacity of soils, this was observed mainly in the RCP 8.5 scenario in the last decades of the century.
Identifying interspecific associations is very important for understanding the community assembly process. However, most methods provide only an average association and assume that the association strength does not vary along the environmental gradient or with time. The scale effects are generally ignored. We integrated the idea of wavelet and network topological analysis to provide a novel way to detect non‐random species associations across scales and along gradients using continuous or presence‐absence ecological data. We first used a simulated species distribution dataset to illustrate how the wavelet correlation analysis builds an association matrix and demonstrates its statistical robustness. Then, we applied the wavelet correlation network to a presence‐absence dataset of soil invertebrates. We found that the associations of invertebrates varied along an altitudinal gradient. We conclude by discussing several possible extensions of this method, such as predicting community assembly, utility in the temporal dimension, and the shifting effects of highly connected species within a community. The combination of the multi‐scale decomposition of wavelet and network topology analysis has great potential for fostering an understanding of the assembly and succession of communities, as well as predicting their responses to future climate change across spatial or temporal scales.
Rangeland production is sensitive to climate conditions. In this study, we monitored actual and potential production in the climate zones of Chaharmahal and Bakhtiari province in central Zagros, Iran, from 2000-2016. Net primary production (NPP), light use efficiency (LUE) and rain use efficiency (RUE) were extracted from climatic and MODIS satellite data using the Carnegie-Ames-Stanford approach (CASA) and Miami models. The accuracy of the modeled NPP maps was assessed using regression analysis, based on field data collected at 750 sites under different rangeland conditions. The spatial distribution of NPP and RUE indicated that annual production and photosynthetic efficiency in degraded rangelands with poor and very poor conditions have decreased compared to those of moderate-good classes. The highest relationship between the field and modeled NPP was associated with the Astragalus spp . - Ferula spp. (R ² = 0.865, p < 0.001) in the humid and cold climate zone with good rangeland conditions while the lowest was observed in the annual grasses-annual forbs (R ² = 0.198, p < 0.001) vegetation type with very poor rangeland conditions within the semi-arid and cold climate zone. Furthermore, the highest and lowest NPP values were observed in the Daphne mucronata-Prangos ferulacea (48.38 g C m ⁻² yr ⁻¹ ) and annual grasses-annual forbs (3.42 g C m ⁻² yr ⁻¹ ) vegetation types with LUE values of 0.13 and 0.02 g C MJ ⁻¹ within the humid and cold and the semi-humid and cold climate zones, respectively. According to these findings, remote sensing-based differences between actual and potential NPP can be used as a valuable tool for identification of human impacts on broad rangeland ecosystems..
Grasslands cover an estimated 31%–43% of the Earth’s land surface, possess an intrinsic conservation value, and offer indispensable ecosystem services. However, grasslands have been extensively managed and exploited, face major threats, including land-use change, climate change, woody encroachment, and biological invasion. The primary tools used to sustainably manage grassland soils include prescribed fire, grazing and mowing, and soil amendments. We present four research highlights describing contemporary, leading-edge grassland research examining the importance of plant, soil, and microbial interactions; the underappreciated role of “biocrusts”; and the use of novel crop systems for climate change mitigation. Our synthesis suggests that to sustainably manage grassland soils, we must (1) consider interactions between different above- and belowground ecosystem components; (2) navigate the complex trade-offs produced by different management actions; (3) develop contextual, case-specific best management practices; (4) and integrate the practices of grassland restoration and the sustainable management of grassland soils.
This study explored the spatiotemporal variability of rangeland NPP in response to drought in Chaharmahal and Bakhtiari province, Iran, from 2000 to 2016 using the Carnegie Ames Stanford Application (CASA) model and Standardized Palmer Drought Index (SPDI). The spatial distribution of NPP and Light Use Efficiency(LUE) values, especially during dry years, indicated a larger dwindling rate for annual NPP
and LUE in poor and very poor conditions compared to fair and good rangelands. During the nine-year drought period (2008–2016), NPP decreased across all rangelands, with the highest average of 5.14 g C/(m2.a) and maximum of 6.42 g C/(m2.a) in annual grass-annual forb and the lowest of 0.95 g C/(m2.a) in the Daphne-Astragalus
type. The correlation between SPDI and NPP varied from R2 > 0.85 (p < 0.001) and R2 < 0.1 (p > 0.01) among the rangeland types. The highest and the lowest sensitivity to drought were observed in the annual
plants and shrublands, respectively.
Many global changes take the form of resource enhancements that have potential to transform multiple aspects of ecosystems from slower to faster cycling, including a suite of both above‐ and belowground variables. We developed a novel analytic approach to measure integrated ecosystem responses to resource‐enhancing global changes, and how such whole ecosystem slow‐to‐fast transitions are linked to diversity and exotic invasions in real‐world ecosystems. We asked how 5‐year experimental rainfall and nutrient enhancements in a natural grassland system affected 16 ecosystem functions, pools and stoichiometry variables considered to indicate slow versus fast cycling. We combined these metrics into a novel index we termed “slow‐fast multifunctionality” and assessed its relationship to plant community diversity and exotic plant dominance. Nutrient and rainfall addition interacted to affect average slow‐fast multifunctionality. Nutrient addition alone pushed the system towards faster cycling, but this effect weakened with the joint addition of rainfall and nutrients. Variables associated with soil nutrient pools and cycling most strongly contributed to this antagonistic interaction. Nutrient and water addition together, respectively, had additive or synergistic effects on plant trait composition and productivity, demonstrating divergence of above‐ and belowground ecosystem responses. Our novel metric of faster cycling was strongly associated with decreased plant species richness and increased exotic species dominance. These results demonstrate the breadth of interacting community and ecosystem changes that ensue when resource limitation is relaxed.
Global warming is projected to shift the phenology and increase the productivity of northern ecosystems1–6. Both changes will further feed back to climate through biophysical and biogeochemical processes and are critical for future prediction7,8. However, it remains unclear whether warming and the extended growing season, especially in autumn, would lead to increased net ecosystem carbon uptake9,10. Here we analyse satellite observations, field measurements and model simulations and show a prevalent radiation limitation on carbon uptake in northern ecosystems, especially in autumn. By comparing the start and end of the growing season estimated from vegetation indices and from solar-induced chlorophyll fluorescence (a proxy for gross primary production11,12 (GPP)), we find a greater change in greenness-based start and end of season than that from GPP, mostly caused by the radiation limitation on photosynthesis. This radiation limitation explains the contrasting responses of autumn net carbon exchanges to warming, using both eddy covariance measurements and model simulations from Coupled Model Intercomparison Project Phase 5. Regions with weak radiation limitation benefit more from warming and enhanced vegetation greenness in autumn, where GPP increases can outweigh the warming-induced respiration carbon losses. With continued warming, radiation limitation will increase and exert a strong upper bound on northern ecosystems to act as carbon sinks. Phenological shifts due to warming extend the growing season for plants, with implications for ecosystem productivity. Carbon uptake through photosynthesis is limited by radiation, particularly in autumn, which explains contrasting regional responses of autumn carbon uptake to rising temperatures.
Ilmastoviisaan luonnonsuojelusuunnittelun pohjaksi tarvitaan tietoa siitä, miten lajit, niiden osapopulaatiot sekä luontotyypit reagoivat muuttuvaan ilmastoon. Samalla tarvitaan tietoa siitä, mitkä lajit ja luontotyypit ovat kaikkein haavoittuvimpia ilmastonmuutokselle ja mitä voidaan tehdä niiden suojelun tukemiseksi. Suojelualueverkosto muuttuvassa ilmastossa (SUMI) -hankkeessa, joka toteutettiin vuosina 2017–2019 Suomen ympäristökeskuksessa (SYKE) ympäristöministeriön rahoittamana, pyrittiin vastaamaan näihin kysymyksiin.
Työn ensimmäisessä osassa selvitettiin lajiominaisuuksien yhteyksiä lajien haavoittuvuuteen ilmastonmuutokselle. Erityisenä kiinnostuksen kohteena oli lisäksi se, miten ilmastonmuutos vaikuttaa EU:n luontodirektiivin liitteiden II ja IV sekä lintudirektiivin liitteen I lajeihin. Kirjallisuusselvityksen avulla kerättiin tietoa lajien havaituista ja ennustetuista vasteista muuttuvaan ilmastoon, ja muutosten suhdetta lajiominaisuuksiin mallinnettiin tilastollisesti. Tarkasteltavia eliöryhmiä olivat linnut, perhoset, putkilokasvit, lahopuuhyönteiset, lahopuusienet ja jäkälät. Lajien ominaisuuksien havaittiin vaikuttuvan niiden haavoittuvuuteen ilmastonmuutokselle; negatiiviset vaikutukset korostuvat pohjoisen viileisiin oloihin, kuten tunturi- ja suoelinympäristöihin erikoistuneilla lajeilla, joiden leviämiskyky on rajoittunut. Eri eliöryhmillä nousi esille myös muita lajien haavoittuvuutta ilmastonmuutokselle heijastelevia ominaisuuksia, joita on tärkeää huomioida lajien hoito- ja suojelusuunnittelussa. Tilastomallien tulosten avulla tunnistettiin ilmastonmuutokselle potentiaalisesti haavoittuvia lajeja, joiden vaste ilmastonmuutokseen on negatiivinen.
Työn toisessa osassa tarkasteltiin ilmastonmuutoksen aiheuttamia havaittuja tai ennustettuja muutoksia luontotyypeissä. Katsaus keskittyi luontodirektiivin liitteen I luontotyyppiryhmiin: rannikko, sisävedet ja rannat, perinnebiotoopit, tunturit, suot, kalliot ja metsät. Ilmastonmuutoksen vaikutukset luontotyyppeihin ovat ensi sijassa laadullisia. Herkimmiksi luontotyypeiksi tunnistettiin rannikon hauru- ja meriajokasvallit sekä primäärisukkessioon liittyvät luontotyypit, lumenviipymät, tunturikoivikot, tunturikankaat, virtavesien latvapurot, Tunturi-Lapin pienvedet, perinnebiotoopit, palsasuot, eteläiset aapasuot, lähteet ja lähdesuot sekä avoimet ja puoliavoimet kallioluontotyypit. Ilmastonmuutoksen myötä lisääntyvät luontaiset häiriöt voivat vaikuttaa positiivisesti metsiin lisäämällä kuolleen puun sekä runsaslahopuustoisten nuorten sukkessiovaiheiden ja lehtipuiden määrää.
Ilmastonmuutokselle haavoittuvien lajien ja luontotyyppien suojelua on mahdollista tukea muodostamalla mahdollisimman kattava luonnonsuojelualueverkosto eri ilmastovyöhykkeille. Lisäksi suojelualueiden ulkopuolella tarvitaan toimia, jotka lisäävät lajien mahdollisuuksia siirtyä uusille alueille ilmaston muuttuessa. Mahdollisia työkaluja tähän tarjoavat esimerkiksi vapaaehtoisen suojelun ohjelmat (METSO), maatalouden ympäristötuki ja HELMI-elinympäristöohjelma. Suojelualueilla on luonnonhoidon ja ennallistamisen keinoin mahdollista hidastaa ilmastonmuutokselle haavoittuvien lajien ja luontotyyppien häviämistä tai heikentymistä. Jos ilmastonmuutoksen hillinnässä ei kuitenkaan onnistuta kansainvälisesti, tapahtuu Suomen luonnossa laajamittainen muutos kuluvan vuosisadan aikana.
The effect of air temperature on photosynthesis is important for the terrestrial carbon cycle. The optimum air temperature for photosynthesis is one of the major parameters in data-driven and process-based photosynthesis models that estimate the gross primary production (GPP) of vegetation under a changing climate. To date, most models use the biome-specific optimum air temperature ( T o p t − b ) parameter. To what degree will the site-specific optimum air temperature ( T o p t − s ) affect GPP simulation results remains unclear. In this study, we estimated T o p t − s by using GPP data from 11 grassland eddy flux tower sites (GPP EC ) and satellite vegetation indices (NDVI and EVI). We found that T opt-s parameter values estimated from EVI have good consistency with those from GPP EC at individual sites. We also evaluated the effects of site-specific and biome-specific optimum air temperature parameters on grassland photosynthesis. The results showed that the use of T o p t − s in the Vegetation Photosynthesis Model improved to various degrees in both daily and annual GPP estimates in those grassland flux tower sites. Our results highlight the necessity and potential for the use of T o p t − s in terrestrial GPP models, especially in those situations with large temperature variation (heatwave and cold spill events).
This report contains an up-to-date assessment of hydro-meteorological and climatic risks for different sectors in Finland. Hydro-meteorological and climatic risks were assessed as a combination of the hazard (hydro-meteorological phenomenon), exposure (location of the asset or people at risk) and vulnerability (features of the asset or people at risk). Therefore, both the changing climate and the role of socioeconomic factors on the risk formation, now and in the future, were considered. Hydro-meteorological events cause risks in Finland in the current climate. For example, thunderstorms, heat waves and heavy rains cause economic and health impacts, and other losses. In the future, the risks will change as climate change will affect adverse hydro-meteorological events. Climate change will gradually increase the risks, especially for ecosystems and infrastructure. The impacts of climate change elsewhere in the world can indirectly be reflected in Finland through global flows and movements of commodity, energy, finance and humans. The systematic assessments of these risks have been initiated only recently.
The aim of the report is to support risk preparedness and adaptation to climate change at different levels of government and in different sectors. The assessment is based mainly on studies and surveys found in the literature and on expert assessments. The work was carried out in the "Assessment of Weather and Climate Risks" (SIETO) project between 2017-2018.
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.
Predicting ecosystem responses to global change is a major challenge in ecology. A critical step in that challenge is to understand how changing environmental conditions influence processes across levels of ecological organization. While direct scaling from individual to ecosystem dynamics can lead to robust and mechanistic predictions, new approaches are needed to appropriately translate questions through the community level. Species invasion, loss, and turnover all necessitate this scaling through community processes, but predicting how such changes may influence ecosystem function is notoriously difficult. We suggest that community-level dynamics can be incorporated into scaling predictions using a trait-based response–effect framework that differentiates the community response to environmental change (predicted by response traits) and the effect of that change on ecosystem processes (predicted by effect traits). We develop a response-and-effect functional framework, concentrating on how the relationships among species' response, effect, and abundance can lead to general predictions concerning the magnitude and direction of the influence of environmental change on function. We then detail several key research directions needed to better scale the effects of environmental change through the community level. These include (1) effect and response trait characterization, (2) linkages between response-and-effect traits, (3) the importance of species interactions on trait expression, and (4) incorporation of feedbacks across multiple temporal scales. Increasing rates of extinction and invasion that are modifying communities worldwide make such a research agenda imperative.
The timing of phenological events exerts a strong control over ecosystem function and leads to multiple feedbacks to the climate system1. Phenology is inherently sensitive to temperature (although the exact sensitivity is disputed2) and recent warming is reported to have led to earlier spring, later autumn3,4 and increased vegetation activity5,6. Such greening could be expected to enhance ecosystem carbon uptake7,8, although reports also suggest decreased uptake for boreal forests4,9. Here we assess changes in phenology of temperate forests over the eastern US during the past two decades, and quantify the resulting changes in forest carbon storage. We combine long-term ground observations of phenology, satellite indices, and ecosystem-scale carbon dioxide flux measurements, along with 18 terrestrial biosphere models. We observe a strong trend of earlier spring and later autumn. In contrast to previous suggestions4,9 we show that carbon uptake through photosynthesis increased considerably more than carbon release through respiration for both an earlier spring and later autumn. The terrestrial biosphere models tested misrepresent the temperature sensitivity of phenology, and thus the e�ect on carbon uptake. Our analysis of the temperature–phenology–carbon coupling suggests a current and possible future enhancement of forest carbon uptake due to changes in phenology. This constitutes a negative feedback to climate change, and is serving to slow the rate of warming.
Question
Are plant traits more closely correlated with mean annual temperature, or with mean annual precipitation?
Location
Global.
Methods
We quantified the strength of the relationships between temperature and precipitation and 21 plant traits from 447,961 species-site combinations worldwide. We used meta-analysis to provide an overall answer to our question.
Results
Mean annual temperature was significantly more strongly correlated with plant traits than was mean annual precipitation.
Conclusions
Our study provides support for some of the assumptions of classical vegetation theory, and points to many interesting directions for future research. The relatively low R2 values for precipitation might reflect the weak link between mean annual precipitation and the availability of water to plants.
Background and aims
Little is known about the soil phosphorus (P) biogeochemical cycling in response to combined warming and grazing, especially in the alpine meadow ecosystem of the Qinghai-Tibet Plateau. Here, we used a free-air temperature enhancement system in a controlled warming-grazing experiment to test the hypothesis that combined warming and grazing would significantly accelerate mineralization of soil organic P.
Methods
A two factorial design of warming (1.2–1.7°C temperature increase) and moderate grazing was utilized. A fractionation method was applied to investigate the sizes of different soil inorganic and organic P fractions.
Results
Results showed that both warming and grazing significantly decreased the quantity of organic P extracted by first NaOH (N(I)Po), as well as the total extractable organic P (TPo) at the 0–10 cm depth. Warming also decreased the total P of soil at 0–10 cm. The combined warming and grazing treatment (WG) led to the reduction of major soil organic P fractions (N(I)Po, TPo) by 40–48% and 28–32%, respectively compared with other treatments at 0–10 cm. The activities of acid and alkaline phosphomonoesterase (AcPME and AlPME) were both enhanced by warming and grazing, and their interaction. Decreased concentrations of soil N(I)Po and TPo were accompanied by increased AcPME activity (P < 0.01) and soil temperature (P < 0.05), indicating the enhanced mineralization of organic P under rising temperature. Meanwhile, leaf biomass P of two major species (Potentilla anserine and Gentiana straminea) within these plots were significantly enhanced by either grazing or warming.
Conclusions
The microbial mineralization of soil organic P could be strongly increased under combined warming and grazing conditions as driven by increasing plant demand for P and enhanced microbial activities.
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.
Standardised procedures have been used to measure 67 traits in 43 common plants of the British flora. This paper provides an interpretation of the most consistent patterns in the resulting matrix by means of correlation, ordination and classification analyses. Only a weak coupling was observed between attributes of the regenerative and established phases of the life history. However, within each phase, attributes were strongly aggregated into sets and a high proportion of the variation between species coincided with a single axis. Attributes of the established phase displayed remarkably consistent trends, with a strong 'Axis 1' being identified by three different multivariate methods. There was a marked correlation between foliar concentrations of N, P, K, Ca and Mg, high concentrations of which coincided with the capacity for rapid growth in productive conditions and an inability to sustain yield under limiting supplies of nutrients. A diverse array of other traits, less immediately involving mineral nutrients, were also entrained in Axis 1; these included life history, root and shoot foraging, the morphology, longevity, tensile strength and palatability of leaves, and the decomposition rate of leaf litter. This pattern occurred in both monocotyledons and dicotyledons and appeared to reflect a tradeoff between attributes conferring an ability for high rates of resource acquisition in productive habitats and those responsible for retention of resource capital in unproductive conditions. The second axis of variation evident in the established phase was related to phylogeny and distinguished between monocotyledons and dicotyledons on the basis of a diverse set of traits including genome size, cell size, root and shoot foraging characteristics and vascular tissues. A third axis was detected in which ephemerals and perennials were separated by differences in attributes such as breeding system, leaf decomposition rate and a set of traits reflecting the small stature of many short-lived plants. In the regenerative phase, the leading axis was clearly related to the widely recognised tradeoff between seed size and seed number and was consistent with current understanding of seed banks, and with modern theories explaining species coexistence in terms of complementary responses to temporal and spatial variation in vegetation gap dynamics. The data provide strong evidence of functional integration between evolutionary specialisations in root and shoot and support Donald's unified theory of competitive ability. The data are not consistent with theories of functional types based upon evolutionary tradeoffs in allocation between root and shoot. We suggest that the evidence assembled here and elsewhere in the current literature points to the existence of primary functional types, including those recognised by Ramenskii and Grime. These functional types can be reconciled with the individuality of plant ecologies in the field and provide an effective basis For interpretation and prediction at various scales from the plant community to regional floras. There are particular opportunities for prediction of successional trajectories, the role of herbivores in vegetation succession and the response of vegetation to eutrophication and extreme climatic events. It is also suggested that aspects of this investigation may provide a Darwinian underpinning for Odum's theory of ecosystem maturation.
Aim This first global quantification of the relationship between leaf traits and soil nutrient fertility reflects the trade-off between growth and nutrient conservation. The power of soils versus climate in predicting leaf trait values is assessed in bivariate and multivariate analyses and is compared with the distribution of growth forms (as a discrete classification of vegetation) across gradients of soil fertility and climate.
Location All continents except for Antarctica.
Methods Data on specific leaf area (SLA), leaf N concentration (LNC), leaf P concentration (LPC) and leaf N:P were collected for 474 species distributed across 99 sites (809 records), together with abiotic information from each study site. Individual and combined effects of soils and climate on leaf traits were quantified using maximum likelihood methods. Differences in occurrence of growth form across soil fertility and climate were determined by one-way ANOVA.
Results There was a consistent increase in SLA, LNC and LPC with increasing soil fertility. SLA was related to proxies of N supply, LNC to both soil total N and P and LPC was only related to proxies of P supply. Soil nutrient measures explained more variance in leaf traits among sites than climate in bivariate analysis. Multivariate analysis showed that climate interacted with soil nutrients for SLA and area-based LNC. Mass-based LNC and LPC were determined mostly by soil fertility, but soil P was highly correlated to precipitation. Relationships of leaf traits to soil nutrients were stronger than those of growth form versus soil nutrients. In contrast, climate determined distribution of growth form more strongly than it did leaf traits.
Main conclusions We provide the first global quantification of the trade-off between traits associated with growth and resource conservation ‘strategies’ in relation to soil fertility. Precipitation but not temperature affected this trade-off. Continuous leaf traits might be better predictors of plant responses to nutrient supply than growth form, but growth forms reflect important aspects of plant species distribution with climate.
Plant functional types (PFTs) bridge the gap between plant physiology and community and ecosystem processes, thus providing a powerful tool in climate change research. We aimed at identifying PFTs within the flora of central-western Argentina, and to explore their possible consequences for ecosystem function. We analyzed 24 vegetative and regenerative traits of the 100 most abundant species along a steep climatic gradient. Based on plant traits and standard multivariate techniques, we identified eight PFTs. Our results confirmed, over a wide range of climatic conditions, the occurrence of broad recurrent patterns of association among plant traits reported for other floras; namely trade-offs between high investment in photosynthesis and growth on the one hand, and preferential allocation to storage and defence on the other. Regenerative traits were only partially coupled with vegetative traits. Using easily-measured plant traits and individual species cover in 63 sites, we predicted main community-ecosystem processes along the regional gradient. We hypothesized likely impacts of global climatic change on PFTs and ecosystems in situ, and analysed their probabilities of migrating in response to changing climatic conditions. Finally, we discuss the advantages and limitations of this kind of approach in predicting changes in plant distribution and in ecosystem processes over the next century.
Despite striking differences in climate, soils, and evolutionary history among diverse biomes ranging from tropical and temperate forests to alpine tundra and desert, we found similar interspecific relationships among leaf structure and function and plant growth in all biomes. Our results thus demonstrate convergent evolution and global generality in plant functioning, despite the enormous diversity of plant species and biomes. For 280 plant species from two global data sets, we found that potential carbon gain (photosynthesis) and carbon loss (respiration) increase in similar proportion with decreasing leaf life-span, increasing leaf nitrogen concentration, and increasing leaf surface area-to-mass ratio. Productivity of individual plants and of leaves in vegetation canopies also changes in constant proportion to leaf life-span and surface area-to-mass ratio. These global plant functional relationships have significant implications for global scale modeling of vegetation-atmosphere CO2 exchange.
In this century, increasing concentrations of carbon dioxide (CO2) and other greenhouse gases in the Earth's atmosphere are expected to cause warmer surface temperatures and changes in precipitation patterns. At the same time, reactive nitrogen is entering natural systems at unprecedented rates. These global environmental changes have consequences for the functioning of natural ecosystems, and responses of these systems may feed back to affect climate and atmospheric composition. Here, we report plant growth responses of an ecosystem exposed to factorial combinations of four expected global environmental changes. We exposed California grassland to elevated CO2, temperature, precipitation, and nitrogen deposition for five years. Root and shoot production did not respond to elevated CO2 or modest warming. Supplemental precipitation led to increases in shoot production and offsetting decreases in root production. Supplemental nitrate deposition increased total production by an average of 26%, primarily by stimulating shoot growth. Interactions among the main treatments were rare. Together, these results suggest that production in this grassland will respond minimally to changes in CO2 and winter precipitation, and to small amounts of warming. Increased nitrate deposition would have stronger effects on the grassland. Aside from this nitrate response, expectations that a changing atmosphere and climate would promote carbon storage by increasing plant growth appear unlikely to be realized in this system.
In experimentally heated plots that each span a soil moisture gradient in a Rocky Mountain meadow, aboveground biomass of
Artemisia tridentata (a sagebrush) increased in the drier habitat and that of Pentaphylloides floribunda (a shrub cinquefoil) increased in the wetter habitat relative to control plots. In contrast, aboveground forb biomass decreased
in the wet and dry habitats of the heated plots. These results, combined with evidence for enhanced sagebrush seedling establishment
rates in the heated plots, suggest that the increased warming expected under an atmosphere with a concentration of carbon
dioxide twice that of pre-industrial levels could change the dominant vegetation of a widespread meadow habitat.
Climate shifts over this century are widely expected to alter the structure and functioning of temperate plant communities. However, long-term climate experiments in natural vegetation are rare and largely confined to systems with the capacity for rapid compositional change. In unproductive, grazed grassland at Buxton in northern England (U.K.), one of the longest running experimental manipulations of temperature and rainfall reveals vegetation highly resistant to climate shifts maintained over 13 yr. Here we document this resistance in the form of: (i) constancy in the relative abundance of growth forms and maintained dominance by long-lived, slow-growing grasses, sedges, and small forbs; (ii) immediate but minor shifts in the abundance of several species that have remained stable over the course of the experiment; (iii) no change in productivity in response to climate treatments with the exception of reduction from chronic summer drought; and (iv) only minor species losses in response to drought and winter heating. Overall, compositional changes induced by 13-yr exposure to climate regime change were less than short-term fluctuations in species abundances driven by interannual climate fluctuations. The lack of progressive compositional change, coupled with the long-term historical persistence of unproductive grasslands in northern England, suggests the community at Buxton possesses a stabilizing capacity that leads to long-term persistence of dominant species. Unproductive ecosystems provide a refuge for many threatened plants and animals and perform a diversity of ecosystem services. Our results support the view that changing land use and overexploitation rather than climate change per se constitute the primary threats to these fragile ecosystems.
• calcareous grassland
• climate manipulation
• global change
• multivariate analysis
• vegetation
. The plant functional types (growth forms) traditionally recognized by arctic ecologists provide a useful framework for predicting vegetation responses to, and effects on, ecosystem processes. These functional types are similar to those objectively defined by cluster analysis based on traits expected to influence ecosystem processes. Principal components analysis showed that two major suites of traits (related to growth rate and woodiness) explain the grouping of species into functional types. These plant functional types are useful because they (1) influence many ecological processes (e.g. productivity, transpiration, and nutrient cycling) in similar ways, (2) predict both responses to and effects on environment, including disturbance regime, and (3) show no strong relationship with traits determining migratory ability (so that no functional type will be eliminated by climatic change simply because it cannot migrate). Circumstantial evidence for the ecological importance of these functional types comes from the distribution of types along environmental gradients and the known ecological effects of traits (e.g., effects of litter quality on decomposition and of plant height on winter albedo) that characterize each functional type. The paleorecord provides independent evidence that some of these functional types have responded predictably to past climatic changes. Field experiments also show that plant functional types respond predictably to changes in soil resources (water and nutrients) but less predictably to temperature. We suggest that evidence for the validity of arctic plant functional types is strong enough to warrant their use in regional models seeking to predict the transient response of arctic ecosystems to global change.
The leaf economics spectrum (LES) provides a useful framework for examining species strategies as shaped by their evolutionary history. However, that spectrum, as originally described, involved only two key resources (carbon and nutrients) and one of three economically important plant organs. Herein, I evaluate whether the economics spectrum idea can be broadly extended to water – the third key resource –stems, roots and entire plants and to individual, community and ecosystem scales. My overarching hypothesis is that strong selection along trait trade-off axes, in tandem with biophysical constraints, results in convergence for any taxon on a uniformly fast, medium or slow strategy (i.e. rates of resource acquisition and processing) for all organs and all resources.
Assessing trait responses to environmental gradients requires the simultaneous analysis of the information contained in three tables: L (species distribution across samples), R (environmental characteristics of samples), and Q (species traits). Among the available methods, the so-called fourth-corner and RLQ methods are two appealing alternatives that provide a direct way to test and estimate trait-nvironment relationships. Both methods are based on the analysis of the fourth-corner matrix, which crosses traits and environmental variables weighted by species abundances. However, they differ greatly in their outputs: RLQ is a multivariate technique that provides ordination scores to summarize the joint structure among the three tables, whereas the fourth-corner method mainly tests for individual trait-environment relationships (i.e., one trait and one environmental variable at a time). Here, we illustrate how the complementarity between these two methods can be exploited to promote new ecological knowledge and to improve the study of trait-environment relationships. After a short description of each method, we apply them to real ecological data to present their different outputs and provide hints about the gain resulting from their combined use.
Populations of the common perennial herb Plantago lanceolata L. have been exposed to nearly two decades of summer drought at the Buxton Climate Change Experiment (BCCIL), a controlled manipulation of climate factors in a species-rich limestone grassland in northern England.We used a common garden approach to test for evidence of selection for different suites of functional traits in P. lanceolata populations exposed to chronic summer drought and across a soil depth gradient.The main axis of functional variation reflected a trade-off between reproductive and vegetative allocation, consistent with drought avoidance and competitive strategies, respectively. Avoidance strategies were more prominent in droughted populations, whereas competitive strategies were more prominent in populations from control treatments. Treatment differences were more pronounced in shallower soils. Deeper soils in both control and drought treatments promoted functional differentiation associated with competitive strategies, suggesting that selective pressures imposed by different climate treatments are modified by fine-scale edaphic heterogeneity.Synthesis. Results suggest that population-level shifts can be a mechanism of resistance to local climate-induced extinction. Trait differentiation with respect to fine-scale variation in soil depth suggests that edaphic heterogeneity fosters high local genetic diversity, which provides a range of local phenotypes upon which drought-based selection may act.
AimThe aim of this study was to test, based on biological theory, which facet of temperature is most closely associated with the elevational and latitudinal low-temperature limits of seven European broad-leaved tree species. We compared three temperature-related potential constraints across three study regions: (1) absolute minimum temperature within 100years; (2) lowest temperatures during the period of bud-break; and (3) length and temperature of the growing season. LocationWestern and Eastern Swiss Alps (1165-2160m a.s.l.) and southern Sweden (57 degrees N-59 degrees N). Methods
In situ temperature was recorded at the high-elevation and high-latitude limits of seven broad-leaved tree species and correlated with temperatures at the nearest weather stations, in order to reconstruct the temperature regime for the past 50years. By applying generalized extreme value distribution theory, we estimated the lowest temperatures recurring during the life span of a tree. ResultsAt their high-elevation limits, five out of the seven tree species experienced winter minimum temperatures considerably warmer than their known maximum freezing resistance in winter. For the bud-break period, potentially damaging temperatures occurred at both the elevational and the latitudinal limits and for all four species for which phenological data were available. Three out of five species for which a latitudinal replicate was available showed a similar length of growing season at their respective elevational and latitudinal limits. The mean temperature during the growing season was always warmer at a species' latitudinal limit than at its elevational limit, and hence this variable does not bear general explanatory power for the range limit. Main conclusionsLow-temperature extremes during bud-break are the most likely candidates for controlling the elevational and latitudinal limits of broad-leaved tree species. The absolute minimum temperature in winter and the mean temperature during the growing season are unlikely to constrain the cold limits of these species. Thus, the results call for the use of temperature data (extremes) during key stages of spring phenology when attempting to explain the low-temperature range limits and to predict the potential range shifts of deciduous tree species.
The leaf economics spectrum (LES) has revolutionized the way many ecologists think about quantifying plant ecological trade-offs. In particular, the LES has connected a clear functional trade-off (long-lived leaves with slow carbon capture vs. short-lived leaves with fast carbon capture) to a handful of easily measured leaf traits. Building on this work, community ecologists are now able to quickly assess species carbon-capture strategies, which may have implications for community-level patterns such as competition or succession. However, there are a number of steps in this logic that require careful examination, and a potential danger arises when interpreting leaf-trait variation among species within communities where trait relationships are weak. Using data from 22 diverse communities, we show that relationships among three common functional traits (photosynthetic rate, leaf nitrogen concentration per mass, leaf mass per area) are weak in communities with low variation in leaf life span (LLS), especially communities dominated by herbaceous or deciduous woody species. However, globally there are few LLS data sets for communities dominated by herbaceous or deciduous species, and more data are needed to confirm this pattern. The context-dependent nature of trait relationships at the community level suggests that leaf-trait variation within communities, especially those dominated by herbaceous and deciduous woody species, should be interpreted with caution.
Increased reactive atmospheric N deposition has been implicated in floristic changes in species-rich acidic and calcareous grasslands, but the fate of this pollutant N in these ecosystems is unknown. This paper reports the first analysis of N budgets and N fluxes for two grasslands in the White Peak area of Derbyshire, one of the most heavily N-polluted locations in the UK. N fluxes were monitored in lysimeter cores (retaining the original turfs) taken from field plots of unimproved acidic and calcareous grasslands that had received (in addition to ambient N deposition) simulated enhanced N deposition treatments of 3.5 and 14 g N m−2 yr−1 for 6 years. The influence of reducing phosphorus limitation was assessed by factorial additions of P. Seasonal leached losses of nitrate, ammonia and organic N were monitored in detail along with estimates of N removal through simulated grazing and gaseous losses through denitrification and volatilization. The rates of N fluxes by these pathways were used to create N budgets for the grasslands. Both grasslands were found to be accumulating much of the simulated additional N deposition: up to 89% accumulated in the calcareous grassland and up to 38% accumulated in the acidic grassland. The major fluxes of N loss from these grasslands were by simulated grazing and leaching of soluble organic N (constituting 90% of leached N under ambient conditions). Leached inorganic N (mainly nitrate) contributed significantly to the output flux of N under the highest N treatment only. Loss of N through ammonia volatilization accounted for less than 6% of the N added as simulated deposition, while denitrification contributed significantly to output fluxes only in the acidic grassland during winter. The implications of the results for ecosystem N balances and the likely consequences of N accumulation on these grasslands are discussed.
Climate change impacts on vegetation are mediated by soil processes that regulate rhizosphere water balance, nutrient dynamics, and ground-level temperatures. For ecosystems characterized by high fine-scale substrate heterogeneity such as grasslands on poorly developed soils, effects of climate change on plant communities may depend on substrate properties that vary at the scale of individuals (<m2), leading to fine-scale shifts in community structure that may go undetected at larger scales. Here, we show in a long-running climate experiment in species-rich limestone grassland in Buxton, England (UK), that the resistance of the community to 15-year manipulations of temperature and rainfall at the plot scale (9 m2) belies considerable community reorganization at the microsite (100 cm2) scale. In individual models of the abundance of the 25 most common species with respect to climate treatment and microsite soil depth, 13 species exhibited significant soil depth affinities, and nine of these have shifted their position along the depth gradient in response to one or more climate treatments. Estimates of species turnover across the depth gradient reviewed in relation to measurements of water potential, nitrogen supply, pH, and community biomass suggest that communities of shallow microsites are responding directly to microenvironmental changes induced by climate manipulation, while those of the deepest microsites are shifting in response to changes in competitive interference from more nutrient-demanding species. Moreover, for several species in summer drought and winter heated treatments, climate response in deep microsites was opposite that of shallow microsites, suggesting microsite variation is contributing to community stability at the whole-plot level. Our study thus demonstrates a strong link between community dynamics and substrate properties, and suggests ecosystems typified by fine-scale substrate heterogeneity may possess a natural buffering capacity in the face of climate change.
A leaf-height-seed (LHS) plant ecology strategy scheme is proposed. The axes would be specific leaf area SLA (light-capturing area deployed per dry mass allocated), height of the plant's canopy at maturity, and seed mass. All axes would be log-scaled. The strategy of a species would be described by its position in the volume formed by the three axes.The advantages of the LHS scheme can be understood by comparing it to Grime's CSR scheme, which has Competitors, Stress-tolerators and Ruderals at the corners of a triangle. The CSR triangle is widely cited as expressing important strategic variation between species. The C–S axis reflects variation in responsiveness to opportunities for rapid growth; in the LHS scheme, SLA reflects the same type of variation. The R axis reflects coping with disturbance; in the LHS scheme, height and seed mass reflect separate aspects of coping with disturbance.A plant ecology strategy scheme that permitted any species worldwide to be readily positioned within the scheme could bring substantial benefits for improved meta-analysis of experimental results, for placing detailed ecophysiology in context, and for coping with questions posed by global change. In the CSR triangle the axes are defined by reference to concepts, there is no simple protocol for positioning species beyond the reference datasets within the scheme, and consequently benefits of worldwide comparison have not materialized. LHS does permit any vascular land plant species to be positioned within the scheme, without time-consuming measurement of metabolic rates or of field performance relative to other species. The merits of the LHS scheme reside (it is argued) in this potential for worldwide comparison, more than in superior explanatory power within any particular vegetation region.The LHS scheme avoids also two other difficulties with the CSR scheme: (a) It does not prejudge that there are no viable strategies under high stress and high disturbance (the missing quadrant in the CSR triangle compared to a two-axis rectangle); (b) It separates out two distinct aspects of the response to disturbance, height at maturity expressing the amount of growth attempted between disturbances, and seed mass (inverse of seed output per unit reproductive effort) expressing the capacity to colonize growth opportunities at a distance.The advantage of LHS axes defined through a single readily-measured variable needs to be weighed against the disadvantage that single plant traits may not capture as much strategy variation as CSR's multi-trait axes. It is argued that the benefits of potential worldwide comparison do actually outweigh any decrease in the proportion of meaningful variation between species that is captured. Further, the LHS scheme opens the path to quantifying what proportion of variation in any other ecologically-relevant trait is correlated with the LHS axes. This quantification could help us to move forward from unprofitable debates of the past 30 years, where CSR opponents have emphasized patterns that were not accommodated within the scheme, while CSR proponents have emphasized patterns that the scheme did account for.
Abstract New analyses are presented addressing the global impacts of recent climate change on phenology of plant and animal species. A meta-analysis spanning 203 species was conducted on published datasets from the northern hemisphere. Phenological response was examined with respect to two factors: distribution of species across latitudes and taxonomic affiliation or functional grouping of target species. Amphibians had a significantly stronger shift toward earlier breeding than all other taxonomic/functional groups, advancing more than twice as fast as trees, birds and butterflies. In turn, butterfly emergence or migratory arrival showed three times stronger advancement than the first flowering of herbs, perhaps portending increasing asynchrony in insect–plant interactions. Response was significantly stronger at higher latitudes where warming has been stronger, but latitude explained −1 advancement. The scientific community has assumed this difference to be real and has attempted to explain it in terms of biologically relevant phenomena: specifically, differences in distribution of data across latitudes, taxa or time periods. Here, these and other possibilities are explored. All analyses indicate that the difference in estimated response is primarily due to differences between the studies in criteria for incorporating data. It is a clear and automatic consequence of the exclusion by one study of data on ‘stable’ (nonresponsive) species. Once this is accounted for, the two studies support each other, generating similar conclusions despite analyzing substantially nonoverlapping datasets. Analyses here on a new expanded dataset estimate an overall spring advancement across the northern hemisphere of 2.8 days decade−1. This is the first quantitative analysis showing that data-sampling methodologies significantly impact global (synthetic) estimates of magnitude of global warming response.
1) The concept of plant functional type proposes that species can be grouped according to common responses to the environment and.or common effects on ecosystem processes. However, the knowledge of relationships between traits associated with the response of plants to environmental factors such as resources and disturbances( response traits), and traits that determine effects of plants on ecosystem function(effect traits), such as biogeochemical cycling or propensity to disturbance, remains rudimentary.
2) We present a framework using concepts and results from community ecology, ecosystem ecology and evolutionary biology to provide this linkage. Ecosystem functioning is the end result of the operation of multiple environmental filters in a heirarchy of scales which, by selecting individuals with appropriate responses, result in assemblages with varying trait composition. Functional linkages and trade-offs among traits, each of which relates to one or several processes, determine whether or not filtering by different factors gives a match, and whether ecosystem effects can easily be deduced from knowledge of the filters.
3) To illustrate this framework we analyse a set of key environmental factors and ecosystem processes. While traits associated with response to nutrient gradients strongly overlapped with those determining net primary production, little direct overlap was found between response to fire and flammability
4) We hypothesise that these patterns reflect general trends. Responses to resource availability would be determined by traits that also involved in biogeochemical cycling because both these responses and effects are driven by the trade-off between acquisition and conservation. On the other hand, regeneration and demographic traits associated with with response to disturbance, which are known to have little connection with adult traits involved in plant ecophysiology, would be of little relevance to ecosystem processes.
5) This framework is likely to be broadly applicable, although caution must to exercised to use trait linkages and trade-offs appropriate to the scale, environmental conditions and evolutionary context. It may direct the selection of plant functional types for vegetation models at a range of scales, and help with the design of experimental studies of relationships between plant diversity and ecosystem properties.
Ecology Letters (2011)
Understanding the sensitivity of tundra vegetation to climate warming is critical to forecasting future biodiversity and vegetation feedbacks to climate. In situ warming experiments accelerate climate change on a small scale to forecast responses of local plant communities. Limitations of this approach include the apparent site-specificity of results and uncertainty about the power of short-term studies to anticipate longer term change. We address these issues with a synthesis of 61 experimental warming studies, of up to 20 years duration, in tundra sites worldwide. The response of plant groups to warming often differed with ambient summer temperature, soil moisture and experimental duration. Shrubs increased with warming only where ambient temperature was high, whereas graminoids increased primarily in the coldest study sites. Linear increases in effect size over time were frequently observed. There was little indication of saturating or accelerating effects, as would be predicted if negative or positive vegetation feedbacks were common. These results indicate that tundra vegetation exhibits strong regional variation in response to warming, and that in vulnerable regions, cumulative effects of long-term warming on tundra vegetation – and associated ecosystem consequences – have the potential to be much greater than we have observed to date.
ABSTRACT Aim Our aim was to quantify climatic influences on key leaf traits and relationships at the global scale. This knowledge provides insight into how plants have adapted to different environmental pressures, and will lead to better calibration of future vegetation–climate models. Location The data set represents vegetation from 175 sites around the world. Methods For more than 2500 vascular plant species, we compiled data on leaf mass per area (LMA), leaf life span (LL), nitrogen concentration (Nmass) and photosynthetic capacity (Amass). Site climate was described with several standard indices. Correlation and regression analyses were used for quantifying relationships between single leaf traits and climate. Standardized major axis (SMA) analyses were used for assessing the effect of climate on bivariate relationships between leaf traits. Principal components analysis (PCA) was used to summarize multidimensional trait variation. Results At hotter, drier and higher irradiance sites, (1) mean LMA and leaf N per area were higher; (2) average LL was shorter at a given LMA, or the increase in LL was less for a given increase in LMA (LL–LMA relationships became less positive); and (3) Amass was lower at a given Nmass, or the increase in Amass was less for a given increase in Nmass. Considering all traits simultaneously, 18% of variation along the principal multivariate trait axis was explained by climate. Main conclusions Trait-shifts with climate were of sufficient magnitude to have major implications for plant dry mass and nutrient economics, and represent substantial selective pressures associated with adaptation to different climatic regimes.