Climate Change Ecology最新文献

Predicting how species respond to changes in climate is critical to conserving biodiversity. Modeling efforts to date have largely centered on predicting the effects of warming temperatures on temperate species phenology. In and near the tropics, the effects of a warming planet on species phenology are more likely to be driven by changes in the seasonal precipitation cycle rather than temperature. To demonstrate the importance of considering precipitation-driven phenology in ecological studies, we present a case study wherein we construct a mechanistic population model for a rare subtropical butterfly (Miami blue butterfly, Cyclargus thomasi bethunebakeri) and use a suite of global climate models to project butterfly populations into the future. Across all iterations of the model, the trajectory of Miami blue populations is uncertain. We identify both biological uncertainty (unknown diapause survival rate) and climate uncertainty (ambiguity in the sign of precipitation change across climate models), and their interaction as key factors that determine persistence vs. extinction. Despite uncertainty, the most optimistic iteration of the model predicts that Miami blue butterfly populations will decline under the higher emissions scenario (RCP 8.5). The lack of climate model agreement across the projection ensemble suggests that investigations into the effect of climate change on precipitation-driven phenology require a higher level of rigor in the uncertainty analysis compared to analogous studies of temperature. For tropical species, a mechanistic approach that incorporates both biological and climate uncertainty is the best path forward to understand the effect shifting precipitation regimes have on phenology and population dynamics.

Climate change and disease are threats to biodiversity that may compound and interact with one another in ways that are difficult to predict. White-nose syndrome (WNS), caused by a cold-loving fungus (Pseudogymnoascus destructans), has had devastating impacts on North American hibernating bats, and impact severity has been linked to hibernaculum microclimate conditions. As WNS spreads across the continent and climate conditions change, anticipating these stressors’ combined impacts may improve conservation outcomes for bats. We build on the recent development of winter species distribution models for five North American bat species, which used a hybrid correlative-mechanistic approach to integrate spatially explicit winter survivorship estimates from a bioenergetic model of hibernation physiology. We apply this bioenergetic model given the presence of P. destructans, including parameters capturing its climate-dependent growth as well as its climate-dependent effects on host physiology, under both current climate conditions and scenarios of future climate change. We then update species distribution models with the resulting survivorship estimates to predict changes in winter hibernacula suitability under future conditions. Exposure to P. destructans is generally projected to decrease bats’ winter occurrence probability, but in many areas, changes in climate are projected to lessen the detrimental impacts of WNS. This rescue effect is not predicted for all species or geographies and may arrive too late to benefit many hibernacula. However, our findings offer hope that proactive conservation strategies to minimize other sources of mortality could allow bat populations exposed to P. destructans to persist long enough for conditions to improve.

Climate change scenarios predict an increase in global temperature and sea level rise. For sea turtles, the association between sea level rise, nest water content and temperature along the beach may influence embryo development and offspring survival. Over three consecutive years (2016 – 2018), a field experiment was conducted on Boa Vista island, Cabo Verde, to assess the potential impacts of tidal inundation on hatching success and hatchling phenotype in loggerhead sea turtles (Caretta caretta). Ninety-three groups of three nests each (N = 279) were relocated to a 5 km stretch of the same beach. Nests in each group were placed at regular intervals of 30 to 60 m across three zones of the beach: the lower “wet” zone, where tidal inundation was a risk, a middle zone, and the upper vegetated zone. Mean emergence and hatching success in the wet treatment was 12.0% and 18.9% respectively. In the middle zone it was 25.6% and 39.5%. In the vegetated zone it was 47.2% and 57.1%. Male hatchling production was severely reduced in the wet zone, probably by nest inundation, with the few hatchlings produced being predominantly male. Female body size and clutch size both had a significant impact on hatchling production and hatchling phenotype. In response to increased global temperatures, male hatchling production may continue in nests laid in areas of high flooding risk. The relocation of clutches to the upper beach areas as a conservation plan could be implemented to reduce the mortality of nests by high tide.

Community ecology is driven by the patterns and drivers of species assemblages. Montane communities, in particular, are extremely vulnerable to climate change and are one of the first ecosystems to experience climate-induced biological responses. Loss of natural areas driven by human alteration of land use in montane areas may further alter the reorganization of regional assemblages. Several studies have shown latitudinal shifts in individual species as a result of climate change in the twenty-first century, however, the effects of these shifts on assemblages are yet unknown. Therefore, in the current study, we aim to examine the impacts of projected climate and Land Use Land Cover (LULC) changes on dominant species assemblages in western Himalaya. We investigated the spatio-temporal variations in species distribution and composition within the assemblages under climate and LULC changes in two sub-regions- temperate and alpine using ensemble bioclimatic envelope modelling and logistic regression models. While the climate change impacts were found to be more profound in the alpine region, the footprints of LULCC are more significant in temperate areas. The key findings of the study reveal- 1) Number of associated species within assemblages may reduce under climate change (CC) as an outcome of the declining extent of species bioclimatic envelopes; 2) climate change-induced emergence of novel assemblages especially in the alpine region, and 3) significant unfavourable impacts on species assemblages in the temperate region owing to the intersection of climate and LULC changes.

Location

Western Himalayan region, India

Time period

1975 – 2015; projected year- 2070

Major Taxa

Vascular plants

We consider the current evidence of climate change effects on marine mammals that occur in U.S. waters relative to past predictions. Compelling cases of such effects have been documented, though few studies have confirmed population-level impacts on abundance or vital rates. While many of the observed effects had been predicted, some unforeseen and relatively acute consequences have also been documented. Effects often occur when climate-induced alterations are superimposed upon marine mammals’ ecological (e.g., predator-prey) relationships or coincident human activities. As they were unanticipated, some of the unpredicted effects of climate change have strained the ability of existing conservation and management systems to respond effectively. The literature is replete with cases suggestive of climate change impacts on marine mammals, but which remain unconfirmed. This uncertainty is partially explained by insufficient research and monitoring designed to reveal the connections. Detecting and mitigating the impacts of climate change will require some realignment of research and monitoring priorities, coupled with rapid and flexible management that includes both conventional and novel conservation interventions.

This study uses radiometric dating, palynological, loss-on-ignition, and X-ray fluorescence analyses to reconstruct the vegetation history and coastal morphological changes at the boreal mangrove range limit along the Gulf of Mexico, based on three sediment cores taken from St. George Island, Apalachicola, Florida, USA. The multi-proxy record indicates that the mangrove stands in the vicinity of St. George Island were formed in the recent decades, and no signs of mangroves were found for the last 1500 years during the Late-Holocene in the sedimentary record. The current mangrove expansion at St. George Island is caused by the recent climate warming instead of a recurring phenomenon tied with cyclical global climate variability. Further analysis based on decadal-scale climatic and environmental records reveal that the accelerated sea-level rise and warmer winters, especially the decrease of winter freeze events in the 21st century, are the most plausible causes for mangrove expansion at their boreal range limit during the recent decades. Under the predicted warming trend and accelerating sea-level rise in the 21st century, it is reasonable to believe that mangrove encroachment into coastal marshes will accelerate at Apalachicola and other areas near their poleward range limits.

Four drivers of global change are acting in concert to speed up the ecology of our coastal and open ocean ecosystems. Ocean warming, nutrient pollution, disturbance, and species additions increase biological and ecological rates, favoring weedy communities and causing pervasive human impacts. Ocean warming via greenhouse gas emissions is accelerating metabolic processes, with effects scaling up to populations and ecosystems. Likewise, supercharging primary production via increased resources (e.g., nutrients and light) is leading to faster, weedier communities in estuarine and coastal ecosystems. Disturbances like ocean heat waves are becoming more frequent, resetting succession, and creating permanently young assemblages, while species additions are transporting the quick-growing and the fecund. The speeding up of marine ecosystems will necessitate changes in the ways we do science, attempt conservation, and use ecosystem services.

Climate change threatens to alter the processes of ecological interactions in addition to the composition and function of communities. Traditional ecological paradigms typically do not account for strong differences in the impacts of environmental stressors by trophic level, focusing instead on differential effects on competitors or functional types. Massive cyanobacterial blooms now represent a common phenomenon across most freshwater and marine communities. Here, we present a perspective considering marine cyanobacterial mats as an extreme but accessible system in which traditional ecological trophic paradigms may be tested, and make recommendations for future research on this topic.

Following the near-eradication of the American chestnut (Castanea dentata) over the last century by an invasive fungal pathogen, progress has been made in recent decades towards generating blight-resistant varieties for restoration in its former native range in the Eastern US. Maximum Entropy species distribution modeling software was used with known surviving specimen locations and environmental data to determine optimal present-day habitat characteristics. Model projection was used to estimate shifts in ideal habitat under moderate and extreme carbon-emission climate scenarios over several time horizons ranging between present day and 2100. Sites with suitable habitat across all scenarios were identified and suggested as restoration targets, most notably lowland New England and high-elevation Southern and Mid-Atlantic Appalachian regions. The current study builds upon previous work by combining fine-resolution data, regional-scale breadth, future climate models, and a different source of chestnut location data to produce a species distribution model that is concurrently useful to local sample collectors, state-level planners and long-term restoration managers.