An official website of the United States government
ABSTRACT Human activity has reshaped ecological communities for thousands of years. While these activities have typically led to habitat loss, some species have successfully exploited human environments. However, the effects of long‐term human land‐use on the distributions of such species are poorly understood. Here, we investigated how land‐use change over the last 12,000 years has altered habitat distributions for a widespread human‐commensal bird, the Pacific swallow (Hirundo tahitica). LocationSoutheast Asia, Melanesia. MethodsWe assessed habitat availability for Pacific swallows using citizen science‐based occurrence records and species distribution models that included (a) only climate data, (b) only land‐use data and (c) both variable sets combined. We evaluated approaches to address the unique spatial biases that arise in unstructured survey data of human‐associated species and determined which models performed best with present‐day occurrence records. We then hindcasted alternative models at 1000‐year intervals over 12,000 years to evaluate the relative effects of climate and human land‐use on long‐term habitat availability. ResultsModels that included both climate and human land‐use variables were the best fit to occurrence records. Standard methods for controlling for spatial bias performed poorly compared with fully sampling the environmental background, highlighting unique considerations for modelling human‐associated species. Hindcasting showed that while climate‐only models predicted little change in habitat availability over time, combined models showed habitat increases beginning more than 5000 years ago and significant expansions of habitat over the last 2000 years. Main ConclusionsHuman land‐use over the last several thousand years has likely provided Pacific swallows with substantial new habitat, which may have led to population size expansions. Incorporating long‐term human land‐use into species distribution models offers insights into when associations with human environments may have arisen and generates testable predictions for how populations respond and adapt to human land‐use change over millennial timescales.
more »
« less
Predicting the suitable habitat distribution of berry plants under climate change
Abstract ContextClimate change is altering suitable habitat distributions of many species at high latitudes. Fleshy fruit-producing plants (hereafter, “berry plants”) are important in arctic food webs and as subsistence resources for human communities, but their response to a warming and increasingly variable climate at a landscape scale has not yet been examined. ObjectivesWe aimed to identify environmental determinants of berry plant distribution and predict how climate change might shift these distributions. MethodsWe used species distribution models to identify characteristics and predict the distribution of suitable habitat under current (2006–2013) and future climate conditions (2081–2100; representative concentration pathways 4.5, 6.0, & 8.5) for five berry plant species:Vaccinium uliginosumL.,Empetrum nigrumL.,Rubus chamaemorusL.,Vaccinium vitis-idaeaL., andViburnum edule(Michx.) Raf.. ResultsElevation, soil characteristics, and January and July temperatures were important drivers of habitat distributions. Future suitable habitat predictions showed net declines in suitable habitat area for all species modeled under almost all future climate scenarios tested. ConclusionsOur work contributes to understanding potential geographic shifts in suitable berry plant habitat with climate change at a landscape scale. Shifting and retracting distributions may alter where communities can harvest, suggesting that access to these resources may become restricted in the future. Our prediction maps may help inform climate adaptation planning as communities anticipate shifting access to harvesting locations.
more »
« less
- PAR ID:
- 10537991
- Publisher / Repository:
- Springer
- Date Published:
- Journal Name:
- Landscape Ecology
- Volume:
- 39
- Issue:
- 2
- ISSN:
- 1572-9761
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Abstract AimThe assembly of species into communities and ecoregions is the result of interacting factors that affect plant and animal distribution and abundance at biogeographic scales. Here, we empirically derive ecoregions for mammals to test whether human disturbance has become more important than climate and habitat resources in structuring communities. LocationConterminous United States. Time Period2010–2021. Major Taxa StudiedTwenty‐five species of mammals. MethodsWe analysed data from 25 mammal species recorded by camera traps at 6645 locations across the conterminous United States in a joint modelling framework to estimate relative abundance of each species. We then used a clustering analysis to describe 8 broad and 16 narrow mammal communities. ResultsClimate was the most important predictor of mammal abundance overall, while human population density and agriculture were less important, with mixed effects across species. Seed production by forests also predicted mammal abundance, especially hard‐mast tree species. The mammal community maps are similar to those of plants, with an east–west split driven by different dominant species of deer and squirrels. Communities vary along gradients of temperature in the east and precipitation in the west. Most fine‐scale mammal community boundaries aligned with established plant ecoregions and were distinguished by the presence of regional specialists or shifts in relative abundance of widespread species. Maps of potential ecosystem services provided by these communities suggest high herbivory in the Rocky Mountains and eastern forests, high invertebrate predation in the subtropical south and greater predation pressure on large vertebrates in the west. Main ConclusionsOur results highlight the importance of climate to modern mammals and suggest that climate change will have strong impacts on these communities. Our new empirical approach to recognizing ecoregions has potential to be applied to expanded communities of mammals or other taxa.more » « less
-
IntroductionForecasting range shifts in response to climate change requires accurate species distribution models (SDMs), particularly at the margins of species' ranges. However, most studies producing SDMs rely on sparse species occurrence datasets from herbarium records and public databases, along with random pseudoabsences. While environmental covariates used to fit SDMS are increasingly precise due to satellite data, the availability of species occurrence records is still a large source of bias in model predictions. We developed distribution models for hybridizing sister species of western and eastern Joshua trees (Yucca brevifoliaandY. jaegeriana, respectively), iconic Mojave Desert species that are threatened by climate change and habitat loss. MethodsWe conducted an intensive visual grid search of online satellite imagery for 672,043 0.25 km2grid cells to identify the two species' presences and absences on the landscape with exceptional resolution, and field validated 29,050 cells in 15,001 km of driving. We used the resulting presence/absence data to train SDMs for each Joshua tree species, revealing the contemporary environmental gradients (during the past 40 years) with greatest influence on the current distribution of adult trees. ResultsWhile the environments occupied byY. brevifoliaandY. jaegerianawere similar in total aridity, they differed with respect to seasonal precipitation and temperature ranges, suggesting the two species may have differing responses to climate change. Moreover, the species showed differing potential to occupy each other's geographic ranges: modeled potential habitat forY. jaegerianaextends throughout the range ofY. brevifolia, while potential habitat forY. brevifoliais not well represented within the range ofY. jaegeriana. DiscussionBy reproducing the current range of the Joshua trees with high fidelity, our dataset can serve as a baseline for future research, monitoring, and management of this species, including an increased understanding of dynamics at the trailing and leading margins of the species' ranges and potential for climate refugia.more » « less
-
Abstract PremiseCompetition from naturalized species and habitat loss are common threats to native biodiversity and may act synergistically to increase competition for decreasing habitat availability. We use Hawaiian dryland ferns as a model for the interactions between land‐use change and competition from naturalized species in determining habitat availability. MethodsWe used fine‐resolution climatic variables and carefully curated occurrence data from herbaria and community science repositories to estimate the distributions of Hawaiian dryland ferns. We quantified the degree to which naturalized ferns tend to occupy areas suitable for native species and mapped the remaining available habitat given land‐use change. ResultsOf all native species,Doryopteris angelicahad the lowest percentage of occurrences of naturalized species in its suitable area whileD. decorahad the highest. However, allDoryopterisspp. had a higher percentage overlap, whilePellaea ternifoliahad a lower percentage overlap, than expected by chance.Doryopteris decoraandD. decipienshad the lowest proportions (<20%) of suitable area covering native habitat. DiscussionAreas characterized by shared environmental preferences of native and naturalized ferns may decrease due to human development and fallowed agricultural lands. Our study demonstrates the value of place‐based application of a recently developed correlative ecological niche modeling approach for conservation risk assessment in a rapidly changing and urbanized island ecosystem.more » « less
-
Abstract PremiseClimate change poses challenges to grasslands, including those of the North American Great Plains Region, where shifts in species distributions and fire dynamics are expected. Our present analysis focuses on remaining grasslands within this largely developed and agricultural region. The differential responses of C4and C3grass species to future climate conditions, particularly in habitat suitability and flammability, are critical for understanding ecosystem changes. MethodsWe used species distribution models to predict shifts in habitat suitability for 37 grass species under future climate scenarios and assessed flammability traits in a free‐air CO2‐enrichment study, focusing on species' physiological responses to elevated CO2, warming, and drought. ResultsOur models predicted that C4species will retain higher habitat suitability, while C3species will decline. Leaf‐level flammability analysis showed that species with higher water‐use efficiency under elevated CO will have lower flammability than under non‐elevated, potentially decreasing the predicted rate of fire spread when such species dominate. In contrast, species with higher growth rates but lower water‐use efficiency may be more flammable. Species‐specific responses varied within functional types. Anticipated shifts in species distributions suggest C4species will become more dominant, potentially altering competitive dynamics and reducing C3diversity. Changes in flammability under future conditions are expected to influence fire regimes, with a predicted decrease in mean community rate of spread due to the dominance of less‐flammable C4species. ConclusionsThese findings highlight the need for adaptive fire management and conservation strategies to maintain biodiversity and ecosystem function in North American grasslands under climate change.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript
- Journal Article:
- https://doi.org/10.1007/s10980-024-01839-7
