ORCID Profile
0000-0002-8291-6316
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Publisher: Wiley
Date: 16-10-2013
DOI: 10.1111/GCB.12370
Abstract: Invasions have increased the size of regional species pools, but are typically assumed to reduce native ersity. However, global-scale tests of this assumption have been elusive because of the focus on exotic species richness, rather than relative abundance. This is problematic because low invader richness can indicate invasion resistance by the native community or, alternatively, dominance by a single exotic species. Here, we used a globally replicated study to quantify relationships between exotic richness and abundance in grass-dominated ecosystems in 13 countries on six continents, ranging from salt marshes to alpine tundra. We tested effects of human land use, native community ersity, herbivore pressure, and nutrient limitation on exotic plant dominance. Despite its widespread use, exotic richness was a poor proxy for exotic dominance at low exotic richness, because sites that contained few exotic species ranged from relatively pristine (low exotic richness and cover) to almost completely exotic-dominated ones (low exotic richness but high exotic cover). Both exotic cover and richness were predicted by native plant ersity (native grass richness) and land use (distance to cultivation). Although climate was important for predicting both exotic cover and richness, climatic factors predicting cover (precipitation variability) differed from those predicting richness (maximum temperature and mean temperature in the wettest quarter). Herbivory and nutrient limitation did not predict exotic richness or cover. Exotic dominance was greatest in areas with low native grass richness at the site- or regional-scale. Although this could reflect native grass displacement, a lack of biotic resistance is a more likely explanation, given that grasses comprise the most aggressive invaders. These findings underscore the need to move beyond richness as a surrogate for the extent of invasion, because this metric confounds monodominance with invasion resistance. Monitoring species' relative abundance will more rapidly advance our understanding of invasions.
Publisher: Springer Science and Business Media LLC
Date: 06-2004
DOI: 10.1038/NATURE02561
Publisher: Proceedings of the National Academy of Sciences
Date: 21-12-2020
Abstract: Understanding ecosystem carbon-cycling responses to atmospheric CO 2 enrichment is critical to preserve bio ersity and maintain vital ecosystem services in grasslands impacted by global change. We conducted an 8-y experiment enriching CO 2 concentrations from preindustrial to midtwenty-first century levels on grassland plant communities on upland, lowland, and alluvial soils. CO 2 enrichment increased the CO 2 efflux from soils to atmosphere in amounts depending on whether the dominant limitation was CO 2 or feedbacks (net positive or negative) from soil moisture and plant species turnover. These findings highlight how multiple concurrent limitations, not single limitations in sequence, regulate the impacts of global change drivers in erse grasslands. Incorporating multiple limitations will improve forecasts of terrestrial carbon sequestration and ecosystem services.
Publisher: Wiley
Date: 03-06-2013
DOI: 10.1111/NPH.12339
Abstract: Plant gas exchange is regulated by stomata, which coordinate leaf‐level water loss with xylem transport. Stomatal opening responds to internal concentrations of CO 2 in the leaf, but changing CO 2 can also lead to changes in stomatal density that influence transpiration. Given that stomatal conductance increases under subambient concentrations of CO 2 and, conversely, that plants lose less water at elevated concentrations, can downstream effects of atmospheric CO 2 be observed in xylem tissue? We approached this problem by evaluating leaf stomatal density, xylem transport, xylem anatomy and resistance to cavitation in Helianthus annuus plants grown under three CO 2 regimes ranging from pre‐industrial to elevated concentrations. Xylem transport, conduit size and stomatal density all increased at 290 ppm relative to ambient and elevated CO 2 concentrations. The shoots of the 290‐ppm‐grown plants were most vulnerable to cavitation, whereas xylem cavitation resistance did not differ in 390‐ and 480‐ppm‐grown plants. Our data indicate that, even as an indirect driver of water loss, CO 2 can affect xylem structure and water transport by coupling stomatal and xylem hydraulic functions during plant development. This plastic response has implications for plant water use under variable concentrations of CO 2 , as well as the evolution of efficient xylem transport.
Publisher: Wiley
Date: 28-01-2018
DOI: 10.1111/GCB.14032
Abstract: Continuing enrichment of atmospheric CO 2 may change plant community composition, in part by altering the availability of other limiting resources including soil water, nutrients, or light. The combined effects of CO 2 enrichment and altered resource availability on species flowering remain poorly understood. We quantified flowering culm and ramet production and biomass allocation to flowering culms/ramets for 10 years in C 4 ‐dominated grassland communities on contrasting soils along a CO 2 concentration gradient spanning pre‐industrial to expected mid‐21st century levels (250–500 μl/L). CO 2 enrichment explained up to 77% of the variation in flowering culm count across soils for three of the five species, and was correlated with flowering culm count on at least one soil for four of five species. In contrast, allocation to flowering culms was only weakly correlated with CO 2 enrichment for two species. Flowering culm counts were strongly correlated with species aboveground biomass (AGB R 2 = .34–.74), a measure of species abundance. CO 2 enrichment also increased soil moisture and decreased light levels within the canopy but did not affect soil inorganic nitrogen availability. Structural equation models fit across the soils suggested species‐specific controls on flowering in two general forms: (1) CO 2 effects on flowering culm count mediated by canopy light level and relative species AGB (species AGB/total AGB) or by soil moisture effects on flowering culm count (2) effects of canopy light level or soil inorganic nitrogen on flowering and/or relative species AGB, but with no significant CO 2 effect. Understanding the heterogeneity in species responses to CO 2 enrichment in plant communities across soils in edaphically variable landscapes is critical to predict CO 2 effects on flowering and other plant fitness components, and species potential to adapt to future environmental changes.
Publisher: Springer Science and Business Media LLC
Date: 04-02-2019
DOI: 10.1038/S41559-018-0790-1
Abstract: Leaf traits are frequently measured in ecology to provide a 'common currency' for predicting how anthropogenic pressures impact ecosystem function. Here, we test whether leaf traits consistently respond to experimental treatments across 27 globally distributed grassland sites across 4 continents. We find that specific leaf area (leaf area per unit mass)-a commonly measured morphological trait inferring shifts between plant growth strategies-did not respond to up to four years of soil nutrient additions. Leaf nitrogen, phosphorus and potassium concentrations increased in response to the addition of each respective soil nutrient. We found few significant changes in leaf traits when vertebrate herbivores were excluded in the short-term. Leaf nitrogen and potassium concentrations were positively correlated with species turnover, suggesting that interspecific trait variation was a significant predictor of leaf nitrogen and potassium, but not of leaf phosphorus concentration. Climatic conditions and pretreatment soil nutrient levels also accounted for significant amounts of variation in the leaf traits measured. Overall, we find that leaf morphological traits, such as specific leaf area, are not appropriate indicators of plant response to anthropogenic perturbations in grasslands.
Publisher: Cold Spring Harbor Laboratory
Date: 10-03-2021
DOI: 10.1101/2021.03.09.434527
Abstract: Interannual variability in grassland primary production is strongly driven by precipitation, nutrient availability and herbivory, but there is no general consensus on the mechanisms linking these variables. If grassland biomass is limited by the single most limiting resource at a given time, then we expect that nutrient addition will not affect biomass production at arid sites. We conducted a distributed experiment manipulating nutrients and herbivores at 44 grassland sites in 8 regions around the world, spanning a broad range in aridity. We estimated the effects of 5-11 years of nutrient addition and herbivore exclusion treatments on precipitation sensitivity of biomass (proportional change in biomass relative to proportional change in rainfall among years), and the biomass in the driest year (to measure treatment effects when water was most limiting) at each site. Grazer exclusion did not interact with nutrients to influence driest year biomass or sensitivity. Nutrient addition increased driest year biomass by 74% and sensitivity by 0.12 (proportional units), and that effect did not change across the range of aridity spanned by our sites. Grazer exclusion did not interact with nutrients to influence sensitivity or driest year biomass. At almost half of our sites, the previous year's rainfall explained as much variation in biomass as current year precipitation. Overall, our distributed fertilization experiment detected co-limitation between nutrients and water governing grasslands, with biomass sensitivity to precipitation being limited by nutrient availability irrespective of site aridity and herbivory. Our findings refute the classical ideas that grassland plant performance is limited by the single most limiting resource at a site. This suggests that nutrient eutrophication will destabilize grassland ecosystems through increased sensitivity to precipitation variation.
Publisher: Oxford University Press (OUP)
Date: 10-2008
DOI: 10.1641/B580908
Publisher: Wiley
Date: 14-03-2014
DOI: 10.1111/GEB.12157
Publisher: Wiley
Date: 06-2023
DOI: 10.1002/ECS2.4542
Abstract: Human activities are altering ecological communities around the globe. Understanding the implications of these changes requires that we consider the composition of those communities. However, composition can be summarized by many metrics which in turn are influenced by different ecological processes. For ex le, incidence‐based metrics strongly reflect species gains or losses, while abundance‐based metrics are minimally affected by changes in the abundance of small or uncommon species. Furthermore, metrics might be correlated with different predictors. We used a globally distributed experiment to examine variation in species composition within 60 grasslands on six continents. Each site had an identical experimental and s ling design: 24 plots × 4 years. We expressed compositional variation within each site—not across sites—using abundance‐ and incidence‐based metrics of the magnitude of dissimilarity (Bray–Curtis and Sorensen, respectively), abundance‐ and incidence‐based measures of the relative importance of replacement (balanced variation and species turnover, respectively), and species richness at two scales (per plot‐year [alpha] and per site [gamma]). Average compositional variation among all plot‐years at a site was high and similar to spatial variation among plots in the pretreatment year, but lower among years in untreated plots. For both types of metrics, most variation was due to replacement rather than nestedness. Differences among sites in overall within‐site compositional variation were related to several predictors. Environmental heterogeneity (expressed as the CV of total aboveground plant biomass in unfertilized plots of the site) was an important predictor for most metrics. Biomass production was a predictor of species turnover and of alpha ersity but not of other metrics. Continentality (measured as annual temperature range) was a strong predictor of Sorensen dissimilarity. Metrics of compositional variation are moderately correlated: knowing the magnitude of dissimilarity at a site provides little insight into whether the variation is driven by replacement processes. Overall, our understanding of compositional variation at a site is enhanced by considering multiple metrics simultaneously. Monitoring programs that explicitly incorporate these implications, both when designing s ling strategies and analyzing data, will have a stronger ability to understand the compositional variation of systems and to quantify the impacts of human activities.
Publisher: Springer Science and Business Media LLC
Date: 06-07-2015
Abstract: Terrestrial ecosystem productivity is widely accepted to be nutrient limited(1). Although nitrogen (N) is deemed a key determinant of aboveground net primary production (ANPP)(2,3), the prevalence of co-limitation by N and phosphorus (P) is increasingly recognized(4-8). However, the extent to which terrestrial productivity is co-limited by nutrients other than N and P has remained unclear. Here, we report results from a standardized factorial nutrient addition experiment, in which we added N, P and potassium (K) combined with a selection of micronutrients (K+μ), alone or in concert, to 42 grassland sites spanning five continents, and monitored ANPP. Nutrient availability limited productivity at 31 of the 42 grassland sites. And pairwise combinations of N, P, and K+μ co-limited ANPP at 29 of the sites. Nitrogen limitation peaked in cool, high latitude sites. Our findings highlight the importance of less studied nutrients, such as K and micronutrients, for grassland productivity, and point to significant variations in the type and degree of nutrient limitation. We suggest that multiple-nutrient constraints must be considered when assessing the ecosystem-scale consequences of nutrient enrichment.
Publisher: Springer Science and Business Media LLC
Date: 15-06-2022
DOI: 10.1007/S11104-022-05498-Y
Abstract: The amount of nitrogen (N) derived from symbiotic N 2 fixation by legumes in grasslands might be affected by anthropogenic N and phosphorus (P) inputs, but the underlying mechanisms are not known. We evaluated symbiotic N 2 fixation in 17 natural and semi-natural grasslands on four continents that are subjected to the same full-factorial N and P addition experiment, using the 15 N natural abundance method. N as well as combined N and P (NP) addition reduced aboveground legume biomass by 65% and 45%, respectively, compared to the control, whereas P addition had no significant impact. Addition of N and/or P had no significant effect on the symbiotic N 2 fixation per unit legume biomass. In consequence, the amount of N fixed annually per grassland area was less than half in the N addition treatments compared to control and P addition, irrespective of whether the dominant legumes were annuals or perennials. Our results reveal that N addition mainly impacts symbiotic N 2 fixation via reduced biomass of legumes rather than changes in N 2 fixation per unit legume biomass. The results show that soil N enrichment by anthropogenic activities significantly reduces N 2 fixation in grasslands, and these effects cannot be reversed by additional P amendment.
Publisher: Springer Science and Business Media LLC
Date: 04-12-2017
DOI: 10.1038/S41559-017-0395-0
Abstract: Bio ersity is declining in many local communities while also becoming increasingly homogenized across space. Experiments show that local plant species loss reduces ecosystem functioning and services, but the role of spatial homogenization of community composition and the potential interaction between ersity at different scales in maintaining ecosystem functioning remains unclear, especially when many functions are considered (ecosystem multifunctionality). We present an analysis of eight ecosystem functions measured in 65 grasslands worldwide. We find that more erse grasslands-those with both species-rich local communities (α- ersity) and large compositional differences among localities (β- ersity)-had higher levels of multifunctionality. Moreover, α- and β- ersity synergistically affected multifunctionality, with higher levels of ersity at one scale lifying the contribution to ecological functions at the other scale. The identity of species influencing ecosystem functioning differed among functions and across local communities, explaining why more erse grasslands maintained greater functionality when more functions and localities were considered. These results were robust to variation in environmental drivers. Our findings reveal that plant ersity, at both local and landscape scales, contributes to the maintenance of multiple ecosystem services provided by grasslands. Preserving ecosystem functioning therefore requires conservation of bio ersity both within and among ecological communities.
Publisher: Wiley
Date: 23-11-2018
DOI: 10.1111/NPH.15562
Abstract: Atmospheric CO
Publisher: Oxford University Press (OUP)
Date: 2003
Publisher: Wiley
Date: 30-11-2022
Abstract: Declines in grassland ersity in response to nutrient addition are a general consequence of global change. This decline in species richness may be driven by multiple underlying processes operating at different time‐scales. Nutrient addition can reduce ersity by enhancing the rate of local extinction via competitive exclusion, or by reducing the rate of colonization by constraining the pool of species able to colonize under new conditions. Partitioning net change into extinction and colonization rates will better delineate the long‐term effect of global change in grasslands. We synthesized changes in richness in response to experimental fertilization with nitrogen, phosphorus and potassium with micronutrients across 30 grasslands. We quantified changes in local richness, colonization, and extinction over 8–10 years of nutrient addition, and compared these rates against control conditions to isolate the effect of nutrient addition from background dynamics. Total richness at steady state in the control plots was the sum of equal, relatively high rates of local colonization and extinction. On aggregate, 30%–35% of initial species were lost and the same proportion of new species were gained at least once over a decade. Absolute turnover increased with site‐level richness but was proportionately greater at lower‐richness sites relative to starting richness. Loss of total richness with nutrient addition, especially N in combination with P or K, was driven by enhanced rates of extinction with a smaller contribution from reduced colonization. Enhanced extinction and reduced colonization were disproportionately among native species, perennials, and forbs. Reduced colonization plateaued after the first few ( ) years after nutrient addition, while enhanced extinction continued throughout the first decade. Synthesis . Our results indicate a high rate of colonizations and extinctions underlying the richness of ambient communities and that nutrient enhancement drives overall declines in ersity primarily by exclusion of previously established species. Moreover, enhanced extinction continues over long time‐scales, suggesting continuous, long‐term community responses and a need for long‐term study to fully realize the extinction impact of increased nutrients on grassland composition.
Publisher: Wiley
Date: 06-10-2021
DOI: 10.1111/ELE.13894
Abstract: Fertilisation experiments have demonstrated that nutrient availability is a key determinant of biomass production and carbon sequestration in grasslands. However, the influence of nutrients in explaining spatial variation in grassland biomass production has rarely been assessed. Using a global dataset comprising 72 sites on six continents, we investigated which of 16 soil factors that shape nutrient availability associate most strongly with variation in grassland aboveground biomass. Climate and N deposition were also considered. Based on theory‐driven structural equation modelling, we found that soil micronutrients (particularly Zn and Fe) were important predictors of biomass and, together with soil physicochemical properties and C:N, they explained more unique variation (32%) than climate and N deposition (24%). However, the association between micronutrients and biomass was absent in grasslands limited by NP. These results highlight soil properties as key predictors of global grassland biomass production and point to serial co‐limitation by NP and micronutrients.
Publisher: Elsevier BV
Date: 2023
Publisher: Springer Science and Business Media LLC
Date: 16-02-2014
DOI: 10.1038/NATURE13014
Abstract: Studies of experimental grassland communities have demonstrated that plant ersity can stabilize productivity through species asynchrony, in which decreases in the biomass of some species are compensated for by increases in others. However, it remains unknown whether these findings are relevant to natural ecosystems, especially those for which species ersity is threatened by anthropogenic global change. Here we analyse ersity-stability relationships from 41 grasslands on five continents and examine how these relationships are affected by chronic fertilization, one of the strongest drivers of species loss globally. Unmanipulated communities with more species had greater species asynchrony, resulting in more stable biomass production, generalizing a result from bio ersity experiments to real-world grasslands. However, fertilization weakened the positive effect of ersity on stability. Contrary to expectations, this was not due to species loss after eutrophication but rather to an increase in the temporal variation of productivity in combination with a decrease in species asynchrony in erse communities. Our results demonstrate separate and synergistic effects of ersity and eutrophication on stability, emphasizing the need to understand how drivers of global change interactively affect the reliable provisioning of ecosystem services in real-world systems.
Publisher: Springer Science and Business Media LLC
Date: 2014
Publisher: Springer Science and Business Media LLC
Date: 15-05-2020
Publisher: Springer Science and Business Media LLC
Date: 31-10-2019
DOI: 10.1038/S41467-019-12948-2
Abstract: Soil nitrogen mineralisation (N min ), the conversion of organic into inorganic N, is important for productivity and nutrient cycling. The balance between mineralisation and immobilisation (net N min ) varies with soil properties and climate. However, because most global-scale assessments of net N min are laboratory-based, its regulation under field-conditions and implications for real-world soil functioning remain uncertain. Here, we explore the drivers of realised (field) and potential (laboratory) soil net N min across 30 grasslands worldwide. We find that realised N min is largely explained by temperature of the wettest quarter, microbial biomass, clay content and bulk density. Potential N min only weakly correlates with realised N min , but contributes to explain realised net N min when combined with soil and climatic variables. We provide novel insights of global realised soil net N min and show that potential soil net N min data available in the literature could be parameterised with soil and climate data to better predict realised N min .
Publisher: American Association for the Advancement of Science (AAAS)
Date: 23-03-2012
Abstract: Pan et al . claim that our results actually support a strong linear positive relationship between productivity and richness, whereas Fridley et al . contend that the data support a strong humped relationship. These responses illustrate how preoccupation with bivariate patterns distracts from a deeper understanding of the multivariate mechanisms that control these important ecosystem properties.
Publisher: Wiley
Date: 08-1990
Publisher: Springer Science and Business Media LLC
Date: 15-07-0001
DOI: 10.1038/NCOMMS8710
Abstract: Exotic species dominate many communities however the functional significance of species’ biogeographic origin remains highly contentious. This debate is fuelled in part by the lack of globally replicated, systematic data assessing the relationship between species provenance, function and response to perturbations. We examined the abundance of native and exotic plant species at 64 grasslands in 13 countries, and at a subset of the sites we experimentally tested native and exotic species responses to two fundamental drivers of invasion, mineral nutrient supplies and vertebrate herbivory. Exotic species are six times more likely to dominate communities than native species. Furthermore, while experimental nutrient addition increases the cover and richness of exotic species, nutrients decrease native ersity and cover. Native and exotic species also differ in their response to vertebrate consumer exclusion. These results suggest that species origin has functional significance, and that eutrophication will lead to increased exotic dominance in grasslands.
Publisher: Wiley
Date: 21-08-2023
Abstract: Intra‐annual (i.e. seasonal) temporal niche partitioning is essential to the maintenance of bio ersity in many plant communities. However, understanding of how climate and global change drivers such as eutrophication influence seasonal niche partitioning in plant assemblages remains limited. We used early‐season and late‐season compositional data collected from 10 grassland sites around the world to explore relationships between climate variability and intra‐annual species segregation (i.e. seasonal β ‐ ersity) and to assess how nutrient enrichment alters seasonal β ‐ ersity in plant communities. We then assessed whether changes in seasonal β ‐ ersity in response to nutrient enrichment are underpinned by species turnover or nestedness and determined how specific functional groups (i.e. annual forbs, perennial forbs, C3 and C4 graminoids and legumes) respond to eutrophication within and across early and late s ling dates. We found a positive relationship between intra‐annual temperature variability and seasonal β ‐ ersity but observed no relationship between intra‐annual precipitation variability and seasonal β ‐ ersity. Nutrient enrichment increased seasonal β ‐ ersity and increased turnover of species between early‐ and late‐season communities. Nutrient enrichment reduced the abundance of C4 graminoids and legumes within and across s ling timepoints and eliminated intra‐annual differences in these groups. In contrast, nutrient enrichment resulted in seasonal differences in C3 graminoids, which were not observed in control conditions and increased abundance of C3 graminoids and annual forbs within and across early and late s ling dates. Synthesis : Our understanding of how grasslands respond to various components of global change is primarily based on studies that document community changes at inter‐annual scales. Using early‐season and late‐season compositional data from 10 grassland sites around the world, we show that nutrient enrichment increases seasonal β ‐ ersity and alters intra‐annual dynamics of specific functional groups in unique ways.
Publisher: Wiley
Date: 02-2011
DOI: 10.1111/J.1461-0248.2010.01584.X
Abstract: Many ecosystems worldwide are dominated by introduced plant species, leading to loss of bio ersity and ecosystem function. A common but rarely tested assumption is that these plants are more abundant in introduced vs. native communities, because ecological or evolutionary-based shifts in populations underlie invasion success. Here, data for 26 herbaceous species at 39 sites, within eight countries, revealed that species abundances were similar at native (home) and introduced (away) sites - grass species were generally abundant home and away, while forbs were low in abundance, but more abundant at home. Sites with six or more of these species had similar community abundance hierarchies, suggesting that suites of introduced species are assembling similarly on different continents. Overall, we found that substantial changes to populations are not necessarily a pre-condition for invasion success and that increases in species abundance are unusual. Instead, abundance at home predicts abundance away, a potentially useful additional criterion for biosecurity programmes.
Publisher: Wiley
Date: 18-01-2021
DOI: 10.1002/ECY.3218
Publisher: Wiley
Date: 23-05-2013
DOI: 10.1111/NPH.12341
Abstract: Examining intraspecific variation in growth and function in relation to climate may provide insight into physiological evolution and adaptation, and is important for predicting species responses to climate change. Under common garden conditions, we grew nine genotypes of the C 4 species Panicum virgatum originating from different temperature and precipitation environments. We hypothesized that genotype productivity, morphology and physiological traits would be correlated with climate of origin, and a suite of adaptive traits would show high broad‐sense heritability ( H 2 ). Genotype productivity and flowering time increased and decreased, respectively, with home‐climate temperature, and home‐climate temperature was correlated with genotypic differences in a syndrome of morphological and physiological traits. Genotype leaf and tiller size, leaf lamina thickness, leaf mass per area ( LMA ) and C : N ratios increased with home‐climate temperature, whereas leaf nitrogen per unit mass ( N m ) and chlorophyll (Chl) decreased with home‐climate temperature. Trait variation was largely explained by genotypic differences ( H 2 = 0.33–0.85). Our results provide new insight into the role of climate in driving functional trait coordination, local adaptation and genetic ergence within species. These results emphasize the importance of considering intraspecific variation in future climate change scenarios.
Publisher: IOP Publishing
Date: 07-12-2018
Publisher: American Association for the Advancement of Science (AAAS)
Date: 23-09-2011
Abstract: Standardized s ling from many sites worldwide was used to address an important ecological problem.
Publisher: Oxford University Press (OUP)
Date: 16-03-2012
DOI: 10.1093/JPE/RTS007
Location: United States of America
Location: United States of America
No related grants have been discovered for Philip Fay.