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1.
Grassland productivity in response to climate change and land use is a global concern. In order to explore the effects of climate change and land use on net primary productivity (NPP), NPP partitioning [fBNPP, defined as the fraction of belowground NPP (BNPP) to NPP], and rain‐use efficiency (RUE) of NPP, we conducted a field experiment with warming (+3 °C), altered precipitation (double and half), and annual clipping in a mixed‐grass prairie in Oklahoma, USA since July, 2009. Across the years, warming significantly increased BNPP, fBNPP, and RUEBNPP by an average of 11.6%, 2.8%, and 6.6%, respectively. This indicates that BNPP was more sensitive to warming than aboveground NPP (ANPP) since warming did not change ANPP and RUEANPP much. Double precipitation stimulated ANPP, BNPP, and NPP but suppressed RUEANPP, RUEBNPP, and RUENPP while half precipitation decreased ANPP, BNPP, and NPP but increased RUEANPP, RUEBNPP, and RUENPP. Clipping interacted with altered precipitation in impacting RUEANPP, RUEBNPP, and RUENPP, suggesting land use could confound the effects of precipitation changes on ecosystem processes. Soil moisture was found to be a main factor in regulating variation in ANPP, BNPP, and NPP while soil temperature was the dominant factor influencing fBNPP. These findings suggest that BNPP is critical point to future research. Additionally, results from single‐factor manipulative experiments should be treated with caution due to the non‐additive interactive effects of warming with altered precipitation and land use (clipping). 相似文献
2.
A frequently advocated approach for forecasting the population‐level impacts of climate change is to project models based on historical, observational relationships between climate and demographic rates. Despite the potential pitfalls of this approach, few historically based population models have been experimentally validated. We conducted a precipitation manipulation experiment to test population models fit to observational data collected from the 1930s to the 1970s for six prairie forb species. We used the historical population models to predict experimental responses to the precipitation manipulations, and compared these predictions to ones generated by a statistical model fit directly to the experimental data. For three species, a sensitivity analysis of the effects of precipitation and grass cover on forb population growth showed consistent results for the historical population models and the contemporary statistical models. Furthermore, the historical population models predicted population growth rates in the experimental plots as well or better than the statistical models, ignoring variation explained by spatial random effects and local density‐dependence. However, for the remaining three species, the sensitivity analyses showed that the historical and statistical models predicted opposite effects of precipitation on population growth, and the historical models were very poor predictors of experimental responses. For these species, historical observations were not well replicated in space, and for two of them the historical precipitation‐demography correlations were weak. Our results highlight the strengths and weaknesses of observational and experimental approaches, and increase our confidence in extrapolating historical relationships to predict population responses to climate change, at least when the historical correlations are strong and based on well‐replicated observations. 相似文献
3.
Nicholas A. McMillan Kyran E. Kunkel Donald L. Hagan David S. Jachowski 《Restoration Ecology》2019,27(2):379-388
Keystone species restoration, or the restoration of species whose effect on an ecosystem is much greater than their abundance would suggest, is a central justification for many wildlife reintroduction projects globally. Following restoration, plains bison (Bison bison L.) have been identified as a keystone species in the tallgrass prairie ecoregion, but we know of no research to document similar effects in the mixed‐grass prairie where restoration efforts are ongoing. This study addresses whether Northern Great Plains (NGP) mixed‐grass prairie plant communities exhibit traits consistent with four central keystone effects documented for bison in the tallgrass prairie. We collected species composition, diversity, abundance, bare ground cover, and plant height data in three treatments: where livestock (Bos taurus L.) continuously grazed, livestock were removed for 10 years, and bison have been introduced and resident for 10 years. We observed mixed support for bison acting as keystone species in this system. Supporting the keystone role of bison, we observed higher species richness and compositional heterogeneity (β‐diversity) in the bison treatment than either the livestock retention or livestock removal treatments. However, we observed comparable forb, bare ground, and plant height heterogeneity between bison‐restored sites and sites where livestock were retained, contradicting reported keystone effects in other systems. Our results suggest that after 10 years of being restored, bison partially fulfill their role as a keystone species in the mixed‐grass prairie, and we encourage continued long‐term data collection to evaluate their influence in the NGP. 相似文献
4.
James A. Margrove David F. R. P. Burslem Jaboury Ghazoul Eyen Khoo Chris J. Kettle Colin R. Maycock 《Biotropica》2015,47(1):66-76
The frequency of extreme precipitation events is predicted to increase in some tropical regions in response to global climate change, but the impacts of this form of disturbance on the structure and dynamics of tropical tree communities across heterogeneous landscapes remain understudied. We determined the effects of an extreme precipitation event (EPE) in July 2006 on mortality of dipterocarps on a 68 ha permanent inventory plot in Sepilok Forest Reserve, Sabah. For stems ≥30 cm dbh, 12 of the 15 species of Dipterocarpaceae on this plot have significant positive and/or negative associations to habitats defined by topography and soil type. Short‐term mortality induced by the EPE was much greater for individuals growing on the alluvial floodplain (13.7%) than in the mudstone (1.4%) or sandstone (0.0%) habitats, but mortality of dipterocarps did not differ among these habitats in the subsequent 5‐yr interval. The likelihood of mortality in response to the EPE was highest for a small group of fast growing dipterocarps that possess low wood density and a strong association to the alluvial forest habitat. This group of species represents a high percentage of dipterocarp individuals but a low proportion of dipterocarp diversity in this habitat. We conclude that disturbance induced by high rainfall events contributes to the episodic nature of tropical forest dynamics, and that increases in the frequency of these events would disproportionately impact low‐lying alluvial forest environments and some of the species growing in them. 相似文献
5.
Abstract. In temperate grasslands, the relative importance of above‐ground competition for light compared to below‐ground competition for water and nutrients is hypothesized to increase with increasing precipitation. Thus, competition for light is likely to exert an increasing influence on canopy structure and species composition as precipitation increases. We quantified canopy structure, light availability and changes in species composition at seven sites across the central grassland region of the United States to determine how these properties change across a precipitation gradient. Across the region, there was a disproportionate increase in leaf area and canopy height with increasing precipitation, indicating that plants become taller and leafier across the gradient. Leaf area index increased by a factor of 12 across the gradient while above‐ground net primary productivity increased by a factor of only 5.5. As precipitation increased, there was decreased light availability at the soil surface, increased seasonal variability in light transmission, increased biomass and leaf area at higher canopy layers and an increased proportion of tallstatured species. These observed changes in canopy structure support the prediction that competition for light increases in importance with increasing precipitation. 相似文献
6.
Kurt O. Reinhart Ylva Lekberg John Klironomos Hafiz Maherali 《Ecology and evolution》2017,7(16):6482-6492
Differences in the direction and degree to which invasive alien and native plants are influenced by mycorrhizal associations could indicate a general mechanism of plant invasion, but whether or not such differences exist is unclear. Here, we tested whether mycorrhizal responsiveness varies by plant invasive status while controlling for phylogenetic relatedness among plants with two large grassland datasets. Mycorrhizal responsiveness was measured for 68 taxa from the Northern Plains, and data for 95 taxa from the Central Plains were included. Nineteen percent of taxa from the Northern Plains had greater total biomass with mycorrhizas while 61% of taxa from the Central Plains responded positively. For the Northern Plains taxa, measurable effects often depended on the response variable (i.e., total biomass, shoot biomass, and root mass ratio) suggesting varied resource allocation strategies when roots are colonized by arbuscular mycorrhizal fungi. In both datasets, invasive status was nonrandomly distributed on the phylogeny. Invasive taxa were mainly from two clades, that is, Poaceae and Asteraceae families. In contrast, mycorrhizal responsiveness was randomly distributed over the phylogeny for taxa from the Northern Plains, but nonrandomly distributed for taxa from the Central Plains. After controlling for phylogenetic similarity, we found no evidence that invasive taxa responded differently to mycorrhizas than other taxa. Although it is possible that mycorrhizal responsiveness contributes to invasiveness in particular species, we find no evidence that invasiveness in general is associated with the degree of mycorrhizal responsiveness. However, mycorrhizal responsiveness among species grown under common conditions was highly variable, and more work is needed to determine the causes of this variation. 相似文献
7.
Determining how ecological communities will respond to global environmental change remains a challenging research problem. Recent meta‐analyses concluded that most communities are undergoing compositional change despite no net change in local species richness. We explored how species richness and composition of co‐occurring plant, grasshopper, breeding bird and small mammal communities in arid and mesic grasslands changed in response to increasing aridity and fire frequency. In the arid system, grassland and shrubland plant and breeding bird communities were undergoing directional change, whereas grasshopper and small mammal communities were stable. In the mesic system, all communities were undergoing directional change regardless of fire frequency. Despite directional change in composition in some communities, species richness of all communities did not change because compositional change resulted more from reordering of species abundances than turnover in species composition. Thus, species reordering, not changes in richness, explains long‐term dynamics in these grass and shrub dominated communities. 相似文献
8.
We assessed vegetation recovery on access roads removed after well abandonment in an active oil‐producing region of northern Great Plains grasslands. We compared extant vegetation on 58 roads, restored 3–22 years previously, to records of species seeded on each and to adjacent, undisturbed prairie, to evaluate main differences between the restored and adjacent community and to explore patterns in the restored plant community over time. The restored plant community was dominated by low richness of seeded non‐native and native grasses and forbs, whereas adjacent prairie had numerous, abundant native graminoids and shrubs and higher richness of native forbs. Cover of seeded species on roads was double that of colonizing species. Disparity in cover of dominant native grasses between the adjacent community and relatively narrow restored roadway suggests that conditions for germination and survival in roadbeds are poor. This is at least partly due to persistence of seeded species. Differences in restored plant composition over time were best explained by changes in species seeded, from non‐natives to natives, and secondarily by successional shifts from ruderal to perennial non‐seeded species. Of the 30 species seeded at least once on these roads, only 10 were commonly used. The long‐term influence of seeding choices in grassland road restorations implies that improvements in these practices will be critical to reversing ecological impacts of roads. 相似文献
9.
Rossa O'Briain 《Ecohydrology》2019,12(5)
Climate change is expected to modify temperature and precipitation patterns throughout Europe, leading to warmer drier summers; wetter, milder winters; and an extended growing season. Alterations to feedbacks between important eco‐physical structuring processes driven by climate change may modulate river morphology, floodplain characteristics, and their biological communities. Current understanding is reviewed and synthesised to explore the potential responses, mechanisms, and ramifications of climatic shifts for the European riverscape. Fundamental drivers of change are expected to be (a) disturbance deviation beyond the historical norm and (b) vegetation morphodynamics, a key river process where ecological and fluvial‐geomorphological attributes interact to shape the physical environment. Increased seasonal temperature, summer drought, and winter flooding may affect the colonisation, growth, and mortality of plant species with consequences for riverscape structure and function as succession patterns adjust with repercussions for hydraulics and sediment dynamics. Such opposing winter and summer climate regimes are likely to impact vegetation patch dynamics, reflected in an increasingly variable patch mosaic as disturbance intensity deviates further from historical background conditions. How changes to climate drivers manifest themselves in individual river systems will also be affected by attributes such as catchment topography, geology, vegetation type, and previous human alterations. Where large scale change occurs, it will have consequences for the type and function of biological communities inhabiting the riverscape. Conventional engineering responses to meteorological disturbance will amplify the effect on river biota by reducing their ecological resilience, highlighting the need for a management response that integrates ecological and societal benefits simultaneously. 相似文献
10.
Tim M. Glasby Peter T. Gibson Roger Laird Daniel S. Swadling Gregory West 《Ecological Management & Restoration》2023,24(1):27-35
There is now considerable evidence that, as the climate continues to warm, bushfires are becoming more common and severe, particularly in regions such as south-eastern Australia. The extraordinary Australian bushfires over the summer of 2019/2020 resulted in the burning of habitats such as highland peat swamps and intertidal estuarine wetlands over unprecedented spatial scales. Across New South Wales, these bushfires affected 183 ha of saltmarshes and 23 ha of mangroves in 19 estuaries. The percentage of fire-affected saltmarsh ranged from 51% to 81% in the worst impacted estuaries, although typically ≤15% of mapped saltmarsh was damaged. Just over 50% of mangroves were burnt in Wonboyn Lake (although this constituted <0.2 ha), whereas in all other estuaries, ≤5% of mangroves were burnt. At the state-wide scale, the likelihood of saltmarshes being affected by fire was unrelated to adjacent terrestrial vegetation; however, mangroves adjacent to burnt wet sclerophyll forest were more likely to burn than not. Burnt mangroves were almost exclusively associated with extreme or high severity fires in adjacent terrestrial vegetation, yet saltmarshes were also impacted in some cases by moderate or low-intensity fires. Many species of saltmarsh plants had re-sprouted or germinated after 6–24 months, but the extent of any recovery or changes in species composition were not quantified. The majority of fire-affected mangrove trees appeared to be dead 24 months after the fires, despite observations of epicormic growth on some trees after six months. Bushfire impacts to estuarine wetlands are likely to become more frequent and results from our work can help target hazard reduction burning that might be considered for minimising damage to mangroves. More work is required to better understand potential longer term impacts and the capacity for natural recovery of estuarine wetlands from bushfires. 相似文献
11.
Abstract. Alien invasions typically reduce species richness of habitats, but few studies have examined their effects on species turnover, the difference in species composition between localities. Agropyron cristatum (L.) Gaertn. (crested wheat grass) has been planted on 6–10 million ha of North American prairie, and is invading native prairie. We studied the invasion of A. cristatum into native prairie by measuring species composition along a gradient from maximum to minimum A. cristatum abundance. As A. cristatum increased, the abundance of most common native species decreased, but one appeared to be unaffected (Bouteloua gracilis (H.B.K.) Lag.), and another (Poa sandbergii Vasey) increased. The effect of A. cristatum on species turnover was investigated by examining species–area curves for areas from 0.5 m2 to 8.0 m2. Species diversity was reduced by 35% at high A. cristatum abundances at all areas. A. cristatum reduced the intercept of the species–area curve, but not the slope, suggesting that A. cristatum affected species turnover proportionally in all areas and habitats. This unusual result may indicate a homogeneous environment where species are distributed randomly. A. cristatum produced almost twice as many seeds as all native grasses combined. The number of seeds collected of native grasses and A. cristatum was highly correlated with the number of seed heads immediately nearby, but not with transect position. This suggests most seeds were dispersed over distances less than 5 m. In sum, the invasion of native prairie by A. cristatum might be related to high rates of seed production, and has the effect of decreasing species turnover by reducing the intercept of the species–area curve. 相似文献
12.
Caroline A. Havrilla John B. Bradford Charles B. Yackulic Seth M. Munson 《Diversity & distributions》2023,29(3):379-394
Aim
Grasslands cover a third of Earth's landmass and provide critical ecosystem services. Anticipating how perennial C3 (cool-season) and C4 (warm-season) grasses respond to climate change will be key to predicting future composition and functioning of grasslands. Here, we evaluate environmental drivers of C3 and C4 perennial distributions and assess how C3 and C4 grass distributions shift in response to future climate change.Location
Western United States.Methods
We developed integrated species distribution models to identify climate and soil drivers of relative abundance of C3 and C4 perennial grasses. We then created projections of species abundances under future climate and evaluated when and where projected shifts in relative abundance were robust across climate models.Results
Historically, C3 grasses occupied areas with lower temperature and more variable precipitation regimes, while C4 grasses occupied areas of higher temperature, greater temperature variability and greater warm-season precipitation. C4 species also occupied narrower soil texture niches. In response to future climate change, C3 grass abundance declined across 74% of areas, while C4 abundance increased across 66% of areas. C3 grasses expanded in mid- to higher-latitude areas with increasing temperature and decreasing seasonality of precipitation. In contrast, C4 grasses increased in higher-latitude regions, but declined in lower-latitude, dryer regions. Results were surprisingly robust across climate scenarios, suggesting high confidence in the direction of these future changes.Main Conclusions
Findings imply C3 and C4 perennial grasses will have highly divergent responses to climate change that may result in grassland functional compositional changes. Increasing temperatures and precipitation variability may favour some C4 grasses, but C4 habitat expansion may be constrained by soil conditions in western USA. Results provide actionable insights for anticipating the impacts of climate change on grass-dominated and co-dominated ecosystems and improving large-scale conservation and restoration efforts. 相似文献13.
BJÖRN WISSEL RYAN N. COOPER PETER R. LEAVITT SAMANTHA V. PHAM 《Global Change Biology》2011,17(1):172-185
Endorheic lakes of the northern Great Plains encompass a wide range of environmental parameters (e.g., salinity, pH, DOC, Ca, nutrients, depth) that vary 1000‐fold among sites and through the past 2000 years due to variation in basin hydrology and evaporative forcing. However, while many environmental parameters are known to individually influence zooplankton diversity and taxonomic composition, relatively little is known of the hierarchical relationships among potential controls or of how regulatory mechanisms may change in response to climate variation on diverse scales. To address these issues, we surveyed 70 lakes within a 100 000 km2 prairie region to simulate the magnitude of environmental change expected to occur over 100–1000 years and to quantify the unique and interactive effects of diverse environmental parameters in regulating pelagic invertebrate community structure at that scale. Multivariate analyses showed that salinity was the principal correlate of changes in invertebrate composition among lakes, with a sequential loss of taxa between salinities of 4 and 50 g total dissolved solids L?1 until one to two species predominated in highly saline systems. In contrast, changes in the concentrations of Ca2+ and other mineral nutrients exerted secondary controls of invertebrate assemblages independent of salinity, whereas lake depth provided a tertiary regulatory mechanism structuring species composition. In contrast to these large‐scale hierarchical patterns, seasonal surveys (May, July, September) of a subset of 21 lakes in each of 2003–2005 revealed that annual meteorological variation had no measurable effect on pelagic invertebrates, despite large differences in temperature, precipitation, and evaporation arising from regional droughts. Together these findings show that pelagic invertebrate communities in saline lakes are resilient to interannual variability in climate, but suggest that lakes of the northern Great Plains may provide a sensitive model to forecast centennial effects of future climate change. 相似文献
14.
Abstract. Questions: This paper examines the long‐term change in the herbaceous layer of semi‐arid vegetation since grazing ceased. We asked whether (1) there were differences in the temporal trends of abundance among growth forms of plants; (2) season of rainfall affected the growth form response; (3) the presence of an invasive species influenced the abundance and species richness of native plants relative to non‐invaded plots, and (4) abundance of native plants and/or species richness was related to the time it took for an invasive species to invade a plot. Location: Alice Springs, Central Australia. Methods: Long‐term changes in the semi‐arid vegetation of Central Australia were measured over 28 years (1976–2004) to partition the effects of rainfall and an invasive perennial grass. The relative abundance (biomass) of all species was assessed 25 times in each of 24 plots (8 m × 1 m) across two sites that traversed floodplains and adjacent foot slopes. Photo‐points, starting in 1972, were also used to provide a broader overview of a landscape that had been intensively grazed by cattle and rabbits prior to the 1970s. Species’abundance data were amalgamated into growth forms to examine their relationship with environmental variation in space and time. Environmental variables included season and amount of rainfall, fire history, soil variability and the colonization of the plots by the exotic perennial grass Cenchrus ciliaris (Buffel grass). Results: Constrained ordination showed that season of rainfall and landscape variables relating to soil depth strongly influenced vegetation composition when Cenchrus was used as a covariate. When Cenchrus was included in constrained ordination, it was strongly related to the decline of all native growth forms over time. Univariate comparisons of non‐invaded vs impacted plots over time revealed unequivocal evidence that Cenchrus had caused the decline of all native growth form groups and species richness. They also revealed a contrasting response of native plants to season of rainfall, with a strong response of native grasses to summer rainfall and forbs to winter rainfall. In the presence of Cenchrus these responses were strongly attenuated. Discussion: Pronounced changes in the composition of vegetation were interpreted as a response to removal of grazing pressure, fluctuations in rainfall and, most importantly, invasion of an exotic grass. Declines in herbaceous species abundance and richness in the presence of Cenchrus appear to be directly related to competition for resources. Indirect effects may also be causing the declines of some woody species from changed fire regimes as a result of increased fuel loads. We predict that Cenchrus will begin to alter landscape level processes as a result of the direct and indirect effects of Cenchrus on the demography of native plants when there is a switch from resource limited (rainfall) establishment of native plants to seed limited recruitment. 相似文献
15.
Elizabeth Starks Ryan Cooper Peter R. Leavitt Björn Wissel 《Global Change Biology》2014,20(4):1032-1042
The anticipated impacts of climate change on aquatic biota are difficult to evaluate because of potentially contrasting effects of temperature and hydrology on lake ecosystems, particularly those closed‐basin lakes within semiarid regions. To address this shortfall, we quantified decade‐scale changes in chemical and biological properties of 20 endorheic lakes in central North America in response to a pronounced transition from a drought to a pluvial period during the early 21st century. Lakes exhibited marked temporal changes in chemical characteristics and formed two discrete clusters corresponding to periods of substantially different effective moisture (as Palmer Drought Severity Index, PDSI). Discriminant function analysis (DFA) explained 90% of variability in fish assemblage composition and showed that fish communities were predicted best by environmental conditions during the arid interval (PDSI 相似文献
16.
Mattia Falaschi Raoul Manenti Wilfried Thuiller Gentile Francesco Ficetola 《Global Change Biology》2019,25(10):3504-3515
The continuous decline of biodiversity is determined by the complex and joint effects of multiple environmental drivers. Still, a large part of past global change studies reporting and explaining biodiversity trends have focused on a single driver. Therefore, we are often unable to attribute biodiversity changes to different drivers, since a multivariable design is required to disentangle joint effects and interactions. In this work, we used a meta‐regression within a Bayesian framework to analyze 843 time series of population abundance from 17 European amphibian and reptile species over the last 45 years. We investigated the relative effects of climate change, alien species, habitat availability, and habitat change in driving trends of population abundance over time, and evaluated how the importance of these factors differs across species. A large number of populations (54%) declined, but differences between species were strong, with some species showing positive trends. Populations declined more often in areas with a high number of alien species, and in areas where climate change has caused loss of suitability. Habitat features showed small variation over the last 25 years, with an average loss of suitable habitat of 0.1%/year per population. Still, a strong interaction between habitat availability and the richness of alien species indicated that the negative impact of alien species was particularly strong for populations living in landscapes with less suitable habitat. Furthermore, when excluding the two commonest species, habitat loss was the main correlate of negative population trends for the remaining species. By analyzing trends for multiple species across a broad spatial scale, we identify alien species, climate change, and habitat changes as the major drivers of European amphibian and reptile decline. 相似文献
17.
Duncan J. Golicher Luis Cayuela J. Rob M. Alkemade Mario González-Espinosa Neptalí Ramírez-Marcial 《Global Ecology and Biogeography》2008,17(2):262-273
Aim Predictive species distribution modelling is a useful tool for extracting the maximum amount of information from biological collections and floristic inventories. However, in many tropical regions records are only available from a small number of sites. This can limit the application of predictive modelling, particularly in the case of rare and endangered species. We aim to address this problem by developing a methodology for defining and mapping species pools associated with climatic variables in order to investigate potential species turnover and regional species loss under climate change scenarios combined with anthropogenic disturbance. Location The study covered an area of 6800 km2 in the highlands of Chiapas, southern Mexico. Methods We derived climatically associated species pools from floristic inventory data using multivariate analysis combined with spatially explicit discriminant analysis. We then produced predictive maps of the distribution of tree species pools using data derived from 451 inventory plots. After validating the predictive power of potential distributions against an independent historical data set consisting of 3105 botanical collections, we investigated potential changes in the distribution of tree species resulting from forest disturbance and climate change. Results Two species pools, associated with moist and cool climatic conditions, were identified as being particularly threatened by both climate change and ongoing anthropogenic disturbance. A change in climate consistent with low‐emission scenarios of general circulation models was shown to be sufficient to cause major changes in equilibrium forest composition within 50 years. The same species pools were also found to be suffering the fastest current rates of deforestation and internal forest disturbance. Disturbance and deforestation, in combination with climate change, threaten the regional distributions of five tree species listed as endangered by the IUCN. These include the endemic species Magnolia sharpii Miranda and Wimmeria montana Lundell. Eleven vulnerable species and 34 species requiring late successional conditions for their regeneration could also be threatened. Main conclusions Climatically associated species pools can be derived from floristic inventory data available for tropical regions using methods based on multivariate analysis even when data limitations prevent effective application of individual species modelling. Potential consequences of climate change and anthropogenic disturbance on the species diversity of montane tropical forests in our study region are clearly demonstrated by the method. 相似文献
18.
- Two dominant drivers of species distributions are climate and habitat, both of which are changing rapidly. Understanding the relative importance of variables that can control distributions is critical, especially for invasive species that may spread rapidly and have strong effects on ecosystems.
- Here, we examine the relative importance of climate and habitat variables in controlling the distribution of the widespread invasive freshwater clam Corbicula fluminea, and we model its future distribution under a suite of climate scenarios using logistic regression and maximum entropy modelling (MaxEnt).
- Logistic regression identified climate variables as more important than habitat variables in controlling Corbicula distribution. MaxEnt modelling predicted Corbicula's range expansion westward and northward to occupy half of the contiguous United States. By 2080, Corbicula's potential range will expand 25–32%, with more than half of the continental United States being climatically suitable.
- Our combination of multiple approaches has revealed the importance of climate over habitat in controlling Corbicula's distribution and validates the climate‐only MaxEnt model, which can readily examine the consequences of future climate projections.
- Given the strong influence of climate variables on Corbicula's distribution, as well as Corbicula's ability to disperse quickly and over long distances, Corbicula is poised to expand into New England and the northern Midwest of the United States. Thus, the direct effects of climate change will probably be compounded by the addition of Corbicula and its own influences on ecosystem function.
19.
Deepa S. Pureswaran Mathieu Neau Maryse Marchand Louis De Grandpr Dan Kneeshaw 《Ecology and evolution》2019,9(1):576-586
Climate change is predicted to alter relationships between trophic levels by changing the phenology of interacting species. We tested whether synchrony between two critical phenological events, budburst of host species and larval emergence from diapause of eastern spruce budworm, increased at warmer temperatures in the boreal forest in northeastern Canada. Budburst was up to 4.6 ± 0.7 days earlier in balsam fir and up to 2.8 ± 0.8 days earlier in black spruce per degree increase in temperature, in naturally occurring microclimates. Larval emergence from diapause did not exhibit a similar response. Instead, larvae emerged once average ambient temperatures reached 10°C, regardless of differences in microclimate. Phenological synchrony increased with warmer microclimates, tightening the relationship between spruce budworm and its host species. Synchrony increased by up to 4.5 ± 0.7 days for balsam fir and up to 2.8 ± 0.8 days for black spruce per degree increase in temperature. Under a warmer climate, defoliation could potentially begin earlier in the season, in which case, damage on the primary host, balsam fir may increase. Black spruce, which escapes severe herbivory because of a 2‐week delay in budburst, would become more suitable as a resource for the spruce budworm. The northern boreal forest could become more vulnerable to outbreaks in the future. 相似文献
20.
Forest ecosystems across western North America will likely see shifts in both tree species dominance and composition over the rest of this century in response to climate change. Our objective in this study was to identify which ecological regions might expect the greatest changes to occur. We used the process‐based growth model 3‐PG, to provide estimates of tree species responses to changes in environmental conditions and to evaluate the extent that species are resilient to shifts in climate over the rest of this century. We assessed the vulnerability of 20 tree species in western North America using the Canadian global circulation model under three different emission scenarios. We provided detailed projections of species shifts by including soil maps that account for the spatial variation in soil water availability and soil fertility as well as by utilizing annual climate projections of monthly changes in air temperature, precipitation, solar radiation, vapor pressure deficit and frost at a spatial resolution of one km. Projected suitable areas for tree species were compared to their current ranges based on observations at >40 000 field survey plots. Tree species were classified as vulnerable if environmental conditions projected in the future appear outside that of their current distribution ≥70% of the time. We added a migration constraint that limits species dispersal to <200 m yr?1 to provide more realistic projections on species distributions. Based on these combinations of constraints, we predicted the greatest changes in the distribution of dominant tree species to occur within the Northwest Forested Mountains and the highest number of tree species stressed will likely be in the North American Deserts. Projected climatic changes appear especially unfavorable for species in the subalpine zone, where major shifts in composition may lead to the emergence of new forest types. 相似文献