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03 Nov 16:44
Preparing for and managing change: climate adaptation for biodiversity and ecosystems
by onlinepublishing@allenpress.com (Bruce A Stein et al)
Frontiers in Ecology and the Environment, Volume 11, Issue 9, Page 502-510, November 2013.
The emerging field of climate-change adaptation has experienced a dramatic increase in attention as the impacts of climate change on biodiversity and ecosystems have become more evident. Preparing for and addressing these changes are now prominent themes in conservation and natural resource policy and practice. Adaptation increasingly is viewed as a way of managing change, rather than just maintaining existing conditions. There is also increasing recognition of the need not only to adjust management strategies in light of climate shifts, but to reassess and, as needed, modify underlying conservation goals. Major advances in the development of climate-adaptation principles, strategies, and planning processes have occurred over the past few years, although implementation of adaptation plans continues to lag. With ecosystems expected to undergo continuing climate-mediated changes for years to come, adaptation can best be thought of as an ongoing process, rather than as a fixed endpoint.
The emerging field of climate-change adaptation has experienced a dramatic increase in attention as the impacts of climate change on biodiversity and ecosystems have become more evident. Preparing for and addressing these changes are now prominent themes in conservation and natural resource policy and practice. Adaptation increasingly is viewed as a way of managing change, rather than just maintaining existing conditions. There is also increasing recognition of the need not only to adjust management strategies in light of climate shifts, but to reassess and, as needed, modify underlying conservation goals. Major advances in the development of climate-adaptation principles, strategies, and planning processes have occurred over the past few years, although implementation of adaptation plans continues to lag. With ecosystems expected to undergo continuing climate-mediated changes for years to come, adaptation can best be thought of as an ongoing process, rather than as a fixed endpoint.
03 Nov 16:44
Evaluating climate impacts on people and ecosystems
by onlinepublishing@allenpress.com (Nancy B Grimm et al)
Frontiers in Ecology and the Environment, Volume 11, Issue 9, Page 455, November 2013.
03 Nov 16:44
Climate change's impact on key ecosystem services and the human well-being they support in the US
by onlinepublishing@allenpress.com (Erik J Nelson et al)
Frontiers in Ecology and the Environment, Volume 11, Issue 9, Page 483-893, November 2013.
Climate change alters the functions of ecological systems. As a result, the provision of ecosystem services and the well-being of people that rely on these services are being modified. Climate models portend continued warming and more frequent extreme weather events across the US. Such weather-related disturbances will place a premium on the ecosystem services that people rely on. We discuss some of the observed and anticipated impacts of climate change on ecosystem service provision and livelihoods in the US. We also highlight promising adaptive measures. The challenge will be choosing which adaptive strategies to implement, given limited resources and time. We suggest using dynamic balance sheets or accounts of natural capital and natural assets to prioritize and evaluate national and regional adaptation strategies that involve ecosystem services.
Climate change alters the functions of ecological systems. As a result, the provision of ecosystem services and the well-being of people that rely on these services are being modified. Climate models portend continued warming and more frequent extreme weather events across the US. Such weather-related disturbances will place a premium on the ecosystem services that people rely on. We discuss some of the observed and anticipated impacts of climate change on ecosystem service provision and livelihoods in the US. We also highlight promising adaptive measures. The challenge will be choosing which adaptive strategies to implement, given limited resources and time. We suggest using dynamic balance sheets or accounts of natural capital and natural assets to prioritize and evaluate national and regional adaptation strategies that involve ecosystem services.
03 Nov 16:44
The impacts of climate change on ecosystem structure and function
by onlinepublishing@allenpress.com (Nancy B Grimm et al)
Frontiers in Ecology and the Environment, Volume 11, Issue 9, Page 474-482, November 2013.
Recent climate-change research largely confirms the impacts on US ecosystems identified in the 2009 National Climate Assessment and provides greater mechanistic understanding and geographic specificity for those impacts. Pervasive climate-change impacts on ecosystems are those that affect productivity of ecosystems or their ability to process chemical elements. Loss of sea ice, rapid warming, and higher organic inputs affect marine and lake productivity, while combined impacts of wildfire and insect outbreaks decrease forest productivity, mostly in the arid and semi-arid West. Forests in wetter regions are more productive owing to warming. Shifts in species ranges are so extensive that by 2100 they may alter biome composition across 5–20% of US land area. Accelerated losses of nutrients from terrestrial ecosystems to receiving waters are caused by both winter warming and intensification of the hydrologic cycle. Ecosystem feedbacks, especially those associated with release of carbon dioxide and methane release from wetlands and thawing permafrost soils, magnify the rate of climate change.
Recent climate-change research largely confirms the impacts on US ecosystems identified in the 2009 National Climate Assessment and provides greater mechanistic understanding and geographic specificity for those impacts. Pervasive climate-change impacts on ecosystems are those that affect productivity of ecosystems or their ability to process chemical elements. Loss of sea ice, rapid warming, and higher organic inputs affect marine and lake productivity, while combined impacts of wildfire and insect outbreaks decrease forest productivity, mostly in the arid and semi-arid West. Forests in wetter regions are more productive owing to warming. Shifts in species ranges are so extensive that by 2100 they may alter biome composition across 5–20% of US land area. Accelerated losses of nutrients from terrestrial ecosystems to receiving waters are caused by both winter warming and intensification of the hydrologic cycle. Ecosystem feedbacks, especially those associated with release of carbon dioxide and methane release from wetlands and thawing permafrost soils, magnify the rate of climate change.
03 Nov 16:44
Climate-change impacts on ecological systems: introduction to a US assessment
by onlinepublishing@allenpress.com (Nancy B Grimm et al)
Frontiers in Ecology and the Environment, Volume 11, Issue 9, Page 456-464, November 2013.
As part of the 2014 US National Climate Assessment, over 60 subject-matter experts from government agencies, academia, nongovernmental organizations, and the private sector assessed the current and projected impacts of climate change on ecosystems, biodiversity, and ecosystem services. Here, we introduce and provide context for the papers included in this Special Issue, drawing upon the key findings from separate assessments of biodiversity, ecosystem structure and function, ecosystem services, climate-change impacts in the context of other stressors, and societal responses to change (ie climate adaptation). We also explain the assessment process and show how the current state of knowledge can be used to identify risks and guide future research and management initiatives.
As part of the 2014 US National Climate Assessment, over 60 subject-matter experts from government agencies, academia, nongovernmental organizations, and the private sector assessed the current and projected impacts of climate change on ecosystems, biodiversity, and ecosystem services. Here, we introduce and provide context for the papers included in this Special Issue, drawing upon the key findings from separate assessments of biodiversity, ecosystem structure and function, ecosystem services, climate-change impacts in the context of other stressors, and societal responses to change (ie climate adaptation). We also explain the assessment process and show how the current state of knowledge can be used to identify risks and guide future research and management initiatives.
01 Nov 07:34
Diversity increases carbon storage and tree productivity in Spanish forests
by Paloma Ruiz-Benito, Lorena Gómez-Aparicio, Alain Paquette, Christian Messier, Jens Kattge, Miguel A. Zavala
Abstract
Aim
Biodiversity loss could reduce primary productivity and the carbon storage provided by forests; however, the mechanisms underpinning the effects of biodiversity on multiple ecosystem functions are not completely understood. Spanish forests are of particular interest because of the broad variation in environmental conditions and management history. We tested for the existence of a relationship between diversity effects and both carbon storage and tree productivity, and examined the relative importance of complementarity and selection mechanisms in a wide variety of forests, from cold deciduous Atlantic to xeric Mediterranean evergreen forests.
Location
Continental Spain.
Methods
We used c. 54,000 plots of the Spanish Forest Inventory and maximum likelihood techniques to quantify how climate, stand structure and diversity shape carbon storage and tree productivity. Diversity effects included both complementarity and selection mechanisms, measured respectively through functional diversity and functional identity measures.
Results
Diversity had a significant effect on both carbon storage and tree productivity, even when controlling for confounding factors of climate and stand structure. A consistent positive effect of functional diversity on carbon storage and tree productivity was observed in all seven forest types studied. This relationship was not linear, and the largest changes in carbon storage and tree productivity were observed at low levels of functional diversity. However, the importance of complementarity effects was not consistent with the productivity of different forest types. Selection effects were particularly important in deciduous and Mediterranean pine forests, but had very little effect on mountain pines.
Main conclusions
We found a generally positive effect of diversity on carbon storage and tree productivity, supported by both complementarity and selection mechanisms. Thus, both functionally diverse forests and functionally important species should be maintained to adequately preserve and promote key ecosystem functions such as carbon storage and tree productivity.
01 Nov 07:33
Population history of fire-prone conifer
by Sakaguchi, S., Bowman, D. M. J. S., Prior, L. D., Crisp, M. D., Linde, C. C., Tsumura, Y., Isagi, Y.
Climate and fire are the key environmental factors that shape the distribution and demography of plant populations in Australia. Because of limited palaeoecological records in this arid continent, however, it is unclear as to which factor impacted vegetation more strongly, and what were the roles of fire regime changes owing to human activity and megafaunal extinction (since ca 50 kya). To address these questions, we analysed historical genetic, demographic and distributional changes in a widespread conifer species complex that paradoxically grows in fire-prone regions, yet is very sensitive to fire. Genetic demographic analysis showed that the arid populations experienced strong bottlenecks, consistent with range contractions during the Last Glacial Maximum (ca 20 kya) predicted by species distribution models. In southern temperate regions, the population sizes were estimated to have been mostly stable, followed by some expansion coinciding with climate amelioration at the end of the last glacial period. By contrast, in the flammable tropical savannahs, where fire risk is the highest, demographic analysis failed to detect significant population bottlenecks. Collectively, these results suggest that the impact of climate change overwhelmed any modifications to fire regimes by Aboriginal landscape burning and megafaunal extinction, a finding that probably also applies to other fire-prone vegetation across Australia.
Lluís likes this
01 Nov 07:32
Mate choice and familiarity
by Senar, J. C., Mateos-Gonzalez, F., Uribe, F., Arroyo, L.
There is currently considerable controversy in evolutionary ecology revolving around whether social familiarity brings attraction when a female chooses a mate. The topic of familiarity is significant because by avoiding or preferring familiar individuals as mates, the potential for local adaptation may be reduced or favoured. The topic becomes even more interesting if we simultaneously analyse preferences for familiarity and sexual ornaments, because when familiarity influences female mating preferences, this could very significantly affect the strength of sexual selection on male ornamentation. Here, we have used mate-choice experiments in siskins Carduelis spinus to analyse how familiarity and patterns of ornamentation (i.e. the size of wing patches) interact to influence mating success. Our results show that females clearly prefer familiar individuals when choosing between familiar and unfamiliar males with similar-sized wing patches. Furthermore, when females were given the choice between a highly ornamented unfamiliar male and a less ornamented familiar male, half of the females still preferred the socially familiar birds as mates. Our finding suggests that male familiarity may be as important as sexual ornaments in affecting female behaviour in mate choice. Given that the potential for local adaptation may be favoured by preferring familiar individuals as mates, social familiarity as a mate-choice criterion may become a potential area of fruitful research on sympatric speciation processes.
01 Nov 07:32
Projecting the impacts of climate change on skipjack tuna abundance and spatial distribution
by Sibylle Dueri, Laurent Bopp, Olivier Maury
Abstract
Climate-induced changes in the physical, chemical, and biological environment are expected to increasingly stress marine ecosystems, with important consequences for fisheries exploitation. Here, we use the APECOSM-E numerical model (Apex Predator ECOSystem Model - Estimation) to evaluate the future impacts of climate change on the physiology, spatial distribution, and abundance of skipjack tuna, the worldwide most fished species of tropical tuna. The main novelties of our approach lie in the mechanistic link between environmental factors, metabolic rates, and behavioral responses and in the fully three dimensional representation of habitat and population abundance. Physical and biogeochemical fields used to force the model are provided by the last generation of the IPSL-CM5 Earth System Model run from 1990 to 2100 under a ‘business-as-usual’ scenario (RCP8.5). Our simulations show significant changes in the spatial distribution of skipjack tuna suitable habitat, as well as in their population abundance. The model projects deterioration of skipjack habitat in most tropical waters and an improvement of habitat at higher latitudes. The primary driver of habitat changes is ocean warming, followed by food density changes. Our projections show an increase of global skipjack biomass between 2010 and 2050 followed by a marked decrease between 2050 and 2095. Spawning rates are consistent with population trends, showing that spawning depends primarily on the adult biomass. On the other hand, growth rates display very smooth temporal changes, suggesting that the ability of skipjack to keep high metabolic rates in the changing environment is generally effective. Uncertainties related to our model spatial resolution, to the lack or simplification of key processes and to the climate forcings are discussed.
Lluís likes this
01 Nov 07:31
Mixed Effects of Long-Term Conservation Investment in Natura 2000 Farmland
by Joana Santana, Luís Reino, Chris Stoate, Rui Borralho, Carlos Rio Carvalho, Stefan Schindler, Francisco Moreira, Miguel N. Bugalho, Paulo Flores Ribeiro, José Lima Santos, Alexandre Vaz, Rui Morgado, Miguel Porto, Pedro Beja
Abstract
Evaluating the effectiveness of conservation funding is crucial for correct allocation of limited resources. Here we used bird monitoring data to assess the effects of long-term conservation investment in a Natura 2000 (N2000) bird protection area (PA), which during two decades benefited from protection regulations, conservation projects, and agri-environment schemes. Variation between 1995–1997 and 2010–2012 in richness and abundance of flagship (Otis tarda, Tetrax tetrax, and Falco naumanni) and specialized fallow field species were more favorable (i.e., increased more or declined less) inside the PA than in a nearby control area. However, the reverse was found for total bird species, farmland, ground-nesting and steppe species, species associated to ploughed fields, and species of European conservation concern. Enhancing the effectiveness of conservation investment in N2000 farmland may require a greater focus on the wider biodiversity alongside that currently devoted to flagship species, as well as improved matching between conservation and agricultural policies.
01 Nov 07:31
El cambio climático desajustará la disponibilidad de elementos esenciales para la vida
Según un estudio internacional que publica hoy la revista Nature, liderado por la Universidad Rey Juan Carlos, factores asociados al cambio climático, como el incremento de aridez, provocarán desajustes en los ciclos del carbono, nitrógeno y fósforo, vitales para el desarrollo de la vida.
01 Nov 07:31
Direct and indirect effects of tree canopy facilitation in the recruitment of Mediterranean oaks
by M. C. Caldeira, I. Ibáñez, C. Nogueira, M. N. Bugalho, X. Lecomte, A. Moreira, J. S. Pereira
Summary
- Tree recruitment in Mediterranean ecosystems is strongly limited at the seedling stage by drought. Increasing evidence shows the critical positive role of the canopy nurse effect on seedling survival which results from direct and indirect, positive and negative interactions between species.
- Most studies, however, have only focused on the effects of tree canopy on water and light, ignoring other critical factors affecting seedling regeneration, such as canopy effects on high temperatures and the competing herb biomass.
- Here, we evaluate how tree canopy cover and removal of herbs affect the survival and growth of seedlings of two dominant Mediterranean Quercus species during a 3-year study. We use an integrated model that combines several data sets to quantify and predict regeneration dynamics along environmental gradients of soil moisture, temperature and light.
- Low soil moisture, increased soil temperature and herb biomass negatively affected seedling survival of both Quercus species. Seedling growth was positively associated with increasing soil moisture and light.
- Although tree canopy cover directly facilitated seedling survival in both Quercus species, it also negatively affected herb biomass and thus indirectly facilitated the survival of Quercus suber, but not of Quercus ilex seedlings at low levels of soil moisture.
- Overall, tree canopies increased seedling survival but not growth during the establishment phase, mainly by ameliorating the effects of low soil moisture and high temperatures. Tree canopy indirectly facilitated survival of Q. suber seedlings by negatively affecting the competing herb layer.
- Synthesis and applications. To improve tree recruitment and conserve Mediterranean Quercus woodlands, the removal of herbs should be integrated into management plans for dry habitats. Interactions between abiotic and biotic factors may also effect the regeneration of these tree species. In particular, a healthy tree canopy will become important for providing conditions to facilitate seedling establishment if these habitats become drier and warmer, as predicted by some climate change scenarios.
29 Oct 20:34
Moving beyond methods: the need for a diverse programme in climate change research
by Ross M. Thompson, John Beardall, Jason Beringer, Mike Grace, Paula Sardina
Abstract
Understanding effects of climate change on ecosystems will require a diverse range of approaches. We proposed using downscaled climate models to generate realistic weather scenarios as experimental treatments. Kreyling et al. propose a gradient approach to determine the shape of response functions. These approaches are different, but highly complementary.
mshocket likes this
29 Oct 20:34
Understanding patterns and processes in models of trophic cascades
by Michael R. Heath, Douglas C. Speirs, John H. Steele
Abstract
Climate fluctuations and human exploitation are causing global changes in nutrient enrichment of terrestrial and aquatic ecosystems and declining abundances of apex predators. The resulting trophic cascades have had profound effects on food webs, leading to significant economic and societal consequences. However, the strength of cascades–that is the extent to which a disturbance is diminished as it propagates through a food web–varies widely between ecosystems, and there is no formal theory as to why this should be so. Some food chain models reproduce cascade effects seen in nature, but to what extent is this dependent on their formulation? We show that inclusion of processes represented mathematically as density-dependent regulation of either consumer uptake or mortality rates is necessary for the generation of realistic ‘top-down’ cascades in simple food chain models. Realistically modelled ‘bottom-up’ cascades, caused by changing nutrient input, are also dependent on the inclusion of density dependence, but especially on mortality regulation as a caricature of, e.g. disease and parasite dynamics or intraguild predation. We show that our conclusions, based on simple food chains, transfer to a more complex marine food web model in which cascades are induced by varying river nutrient inputs or fish harvesting rates.
29 Oct 20:34
Beyond realism in climate change experiments: gradient approaches identify thresholds and tipping points
by Juergen Kreyling, Anke Jentsch, Claus Beier
Abstract
Experimental evidence for impacts of increased climatic variability and extremes on ecosystems is urgently needed. The constraint in our knowledge, however, is not caused by the uncertainty in the applied climate scenarios. We need mechanistic understanding from experiments challenging ecological thresholds coupled with ecosystem models to allow for meaningful up-scaling.
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29 Oct 20:33
Estimating true instead of apparent survival using spatial Cormack–Jolly–Seber models
by Michael Schaub, J. Andrew Royle
Summary
- Survival is often estimated from capture–recapture data using Cormack–Jolly–Seber (CJS) models, where mortality and emigration cannot be distinguished, and the estimated apparent survival probability is the product of the probabilities of true survival and of study area fidelity. Consequently, apparent survival is lower than true survival unless study area fidelity equals one. Underestimation of true survival from capture–recapture data is a main limitation of the method.
- We develop a spatial version of the CJS model that allows estimation of true survival. Besides the information about whether a specific individual was encountered at a given occasion, it is often recorded where the encounter occurred. Thus, information is available about the fraction of dispersal that occurs within the study area, and we use it to model dispersal and estimate true survival. Our model is formulated hierarchically and consists of survival, dispersal and observation submodels, assuming that encounters are possible anywhere within a study area.
- In a simulation study, our new spatial CJS model produced accurate estimates of true survival and dispersal behaviour for various sizes and shapes of the study area, even if emigration is substantial. However, when the information about dispersal is scarce due to low survival, low recapture probabilities and high emigration, the estimators are positively biased. Moreover, survival estimates are sensitive to the assumed dispersal kernel.
- We applied the spatial CJS model to a data set of adult red-backed shrikes (Lanius collurio). Apparent survival of males (c. 0·5) estimated with the CJS model was larger than in females (c. 0·4), but the application of the spatial CJS model revealed that both sexes had similar survival probabilities (c. 0·6). The mean breeding dispersal distance in females was c. 700 m, while males dispersed only c. 250 m between years.
- Spatial CJS models enable study of dispersal and survival independent of study design constraints such as imperfect detection and size of the study area provided that some of the dispersing individuals remain in the study area. We discuss possible extensions of our model: alternative dispersal models and the inclusion of covariates and of a habitat suitability map.
29 Oct 20:33
Hierarchical spatial capture–recapture models: modelling population density in stratified populations
by J. Andrew Royle, Sarah J. Converse
Summary
- Capture–recapture studies are often conducted on populations that are stratified by space, time or other factors. In this paper, we develop a Bayesian spatial capture–recapture (SCR) modelling framework for stratified populations – when sampling occurs within multiple distinct spatial and temporal strata.
- We describe a hierarchical model that integrates distinct models for both the spatial encounter history data from capture–recapture sampling, and also for modelling variation in density among strata. We use an implementation of data augmentation to parameterize the model in terms of a latent categorical stratum or group membership variable, which provides a convenient implementation in popular BUGS software packages.
- We provide an example application to an experimental study involving small-mammal sampling on multiple trapping grids over multiple years, where the main interest is in modelling a treatment effect on population density among the trapping grids.
- Many capture–recapture studies involve some aspect of spatial or temporal replication that requires some attention to modelling variation among groups or strata. We propose a hierarchical model that allows explicit modelling of group or strata effects. Because the model is formulated for individual encounter histories and is easily implemented in the BUGS language and other free software, it also provides a general framework for modelling individual effects, such as are present in SCR models.
26 Oct 10:02
Networks of prey specialization in an Arctic monomorphic seabird
by Jennifer F. Provencher, Kyle H. Elliott, Anthony J. Gaston, Birgit M. Braune
Generalist predator populations are sometimes made up of individuals that specialize on particular prey items. To examine specialization in thick-billed murres Uria lomvia during self-feeding we obtained stomach contents and muscle stable isotope values for 213 birds feeding close to five colonies in the Canadian Arctic. Adults were less specialized during self-feeding than during chick-provisioning. Nonetheless, particular specialists clustered together within the foraging network. While sexes showed similar levels of specialization, individuals of the same sex clustered together within the foraging network. The significant degree of clustering regardless of sex showed that individuals specializing on one prey item tend to also specialize on another, although network topology varied from colony to colony. Adult muscle stable isotope values correlated with the stable isotope values of the prey found in stomachs, at least at the one colony with relevant prey data, suggesting that specializations are maintained over time. Degree of specialization increased with niche width across the five colonies, but similarity in gastro-intestinal and bill morphology was independent of dietary similarity. Thus, although individual specialization is thought to play a key role in sympatric speciation through trophic specialization, we found no support for an association between morphology and foraging patterns in our species. We conclude that self-feeding murres show clustered dietary specialization, and that specialization is highest where diet is most diverse.
26 Oct 10:02
From the matrix to roadsides and beyond: the role of isolated paddock trees as dispersal points for invasion
by Claire Coulson, Peter G. Spooner, Ian D. Lunt, Simon J. Watson
Abstract
Aim
Vertebrate seed dispersers play an important role in determining the spatial distributions of many plants, yet few studies have examined patterns of dispersal in fragmented rural landscapes. This study investigated the factors that influence the occurrence and density of roadside populations of two vertebrate-dispersed trees (Brachychiton populneus and Schinus molle) in roadside environments.
Location
Temperate woodland in southern NSW, Australia.
Methods
Generalized linear models (GLMs) were used to investigate the factors that influence the occurrence and density of the study species in roadsides. Akaike's information criterion (AIC) was used to determine the relative importance of biophysical, disturbance and landscape variables in predictive models for the two species.
Results
We identified two significant determinants of the occurrence of B. populneus and S. molle populations in roadsides: (1) the presence of large ‘perch’ trees of non-target species (predominately Eucalyptus spp.) in roadsides and (2) distance to nearest paddock tree of each target species. These factors were important for both species, but combined to form a stronger predictive model for S. molle than for B. populneus. Factors influencing population density were less clear, although populations of both species tended to be denser on narrow roads.
Main conclusions
Large perch trees were an important predictor of the presence of roadside populations of both species. These results provide criteria to enable roadside managers to either promote native B. populneus, or prevent incursions of exotic S. molle, as desired. Examination of the dispersal pathways for B. populneus and S. molle has revealed that in fragmented agricultural landscapes, isolated paddock trees are able to disperse to nearby roadside environments via frugivore activity. As a result, road networks may provide ‘conduits’ for the movement and potential invasion of vertebrate-dispersed plant species.
26 Oct 10:02
Biophysical forcings of land-use changes from potential forestry activities in North America
by onlinepublishing@allenpress.com (Kaiguang Zhao et al)
Ecological Monographs, Volume 84, Issue 2, Page 329-353, May 2014.
Land-use changes through forestry and other activities alter not just carbon storage, but biophysical properties, including albedo, surface roughness, and canopy conductance, all of which affect temperature. This study assessed the biophysical forcings and climatic impact of vegetation replacement across North America by comparing satellite-derived albedo, land surface temperature (LST), and evapotranspiration (ET) between adjacent vegetation types. We calculated radiative forcings (RF) for potential local conversions from croplands (CRO) or grasslands (GRA) to evergreen needleleaf (ENF) or deciduous broadleaf (DBF) forests. Forests generally had lower albedo than adjacent grasslands or croplands, particularly in locations with snow. They also had warmer nighttime LST, cooler daily and daytime LST in warm seasons, and smaller daily LST ranges. Darker forest surfaces induced positive RFs, dampening the cooling effect of carbon sequestration. The mean (±SD) albedo-induced RFs for each land conversion were equivalent to carbon emissions of 2.2 ± 0.7 kg C/m2 (GRA–ENF), 2.0 ± 0.6 kg C/m2 (CRO–ENF), 0.90 ± 0.50 kg C/m2 (CRO–DBF), and 0.73 ± 0.22 kg C/m2 (GRA–DBF), suggesting that, given the same carbon sequestration potential, a larger net cooling (integrated globally) is expected for planting DBF than ENF. Both changes in LST and ET induce longwave RFs that sometimes had values comparable to or even larger than albedo-induced shortwave RFs. Sensible heat flux, on average, increased when replacing CRO with ENF, but decreased for conversions to DBF, suggesting that DBF tends to cool near-surface air locally while ENF tends to warm it. This local temperature effect showed some seasonal variation and spatial dependence, but did not differ strongly by latitude. Overall, our results show that a carbon-centric accounting is, in many cases, insufficient for climate mitigation policies. Where afforestation or reforestation occurs, however, deciduous broadleaf trees are likely to produce stronger cooling benefits than evergreen needleleaf trees provide.
Land-use changes through forestry and other activities alter not just carbon storage, but biophysical properties, including albedo, surface roughness, and canopy conductance, all of which affect temperature. This study assessed the biophysical forcings and climatic impact of vegetation replacement across North America by comparing satellite-derived albedo, land surface temperature (LST), and evapotranspiration (ET) between adjacent vegetation types. We calculated radiative forcings (RF) for potential local conversions from croplands (CRO) or grasslands (GRA) to evergreen needleleaf (ENF) or deciduous broadleaf (DBF) forests. Forests generally had lower albedo than adjacent grasslands or croplands, particularly in locations with snow. They also had warmer nighttime LST, cooler daily and daytime LST in warm seasons, and smaller daily LST ranges. Darker forest surfaces induced positive RFs, dampening the cooling effect of carbon sequestration. The mean (±SD) albedo-induced RFs for each land conversion were equivalent to carbon emissions of 2.2 ± 0.7 kg C/m2 (GRA–ENF), 2.0 ± 0.6 kg C/m2 (CRO–ENF), 0.90 ± 0.50 kg C/m2 (CRO–DBF), and 0.73 ± 0.22 kg C/m2 (GRA–DBF), suggesting that, given the same carbon sequestration potential, a larger net cooling (integrated globally) is expected for planting DBF than ENF. Both changes in LST and ET induce longwave RFs that sometimes had values comparable to or even larger than albedo-induced shortwave RFs. Sensible heat flux, on average, increased when replacing CRO with ENF, but decreased for conversions to DBF, suggesting that DBF tends to cool near-surface air locally while ENF tends to warm it. This local temperature effect showed some seasonal variation and spatial dependence, but did not differ strongly by latitude. Overall, our results show that a carbon-centric accounting is, in many cases, insufficient for climate mitigation policies. Where afforestation or reforestation occurs, however, deciduous broadleaf trees are likely to produce stronger cooling benefits than evergreen needleleaf trees provide.
26 Oct 10:01
Climatic niche at physiological and macroecological scales: the thermal tolerance–geographical range interface and niche dimensionality
by Sidney F. Gouveia, Joaquín Hortal, Miguel Tejedo, Helder Duarte, Fernanda A. S. Cassemiro, Carlos A. Navas, José Alexandre F. Diniz-Filho
Abstract
Aim
Under the Hutchinsonian concept of the realized niche, biotic interactions and dispersal limitation may prevent species from fully occupying areas that they could tolerate physiologically. This can hamper the translation of physiological limits into climatically defined range limits and distorts inferences of evolutionary changes of the adaptive limits (i.e. niche conservatism). In contrast, heritable physiological limits should conform more closely to the position of the niche in the climatic hyperspace. Here, we hypothesize that a measure of niche position in the climatic hyperspace is more reliable than niche boundaries to capture the variability and evolutionary pattern of physiological tolerance.
Location
Neotropics and Palaeartic.
Methods
We used phylogenetic and non-phylogenetic regressions to test the relationships between physiological requirements and macroecological niche features (i.e. based on known species distributions) among anurans. We use larval critical thermal maximum (CTmax) as a measure of physiological response and maximum temperature (Tmax), temperature variability (Tvar) and the position and breadth of niche in climatic hyperspace as measures of the realized niche in geographical space. We also compare evolutionary rates among these parameters using the phylogenetic signal representation curve.
Results
CTmax is better correlated with niche position (r2 = 0.414) than with Tvar, and CTmax is unrelated to either Tmax or niche breadth. CTmax and macroecological niche position also show similar and rapid evolutionary rates, i.e. faster than Brownian motion, whereas Tmax and Tvar evolve more slowly and niche breadth evolves at random.
Main conclusions
The transferability between thermal tolerance and realized climatic niche limits is weak. Only macroecological niche position in the multivariate climatic hyperspace correlates with physiological tolerance. It thus appears to be more suitable for describing the variability and evolutionary pattern of the species' adaptive limits. We link these results to ‘niche dimensionality’, in that multiple interacting factors outweigh single factors in demarcating the species' realized climatic niche, thereby determining the conserved upper thermal limits of the species.
26 Oct 10:01
Where are the wild things? Why we need better data on species distribution
by Anne Duputié, Niklaus E. Zimmermann, Isabelle Chuine
Abstract
Aim
The effects of ongoing global change are causing increasing concern about the ability of species or biomes to shift or adapt. Tremendous efforts have been made to develop ever more sophisticated species distribution models to provide forecasts for the future of biodiversity. All these models rely on species occurrence data, either for calibration or validation. Here we evaluate (i) whether distribution data diverge among widely used sources, for supposedly well-known taxa, and (ii) to what extent these divergences affect species distribution models.
Location
Europe (as an example).
Methods
We compared the distribution maps of 21 of the most common European trees, according to four large-scale, putatively reliable sources of distribution data. For each species, we compared the outputs of correlative species distribution models built using occurrence data from each of these sources of data. We also investigated how discrepancies in large-scale occurrence data affected the validation scores of two process-based tree distribution models.
Results
Maps of tree occurrence diverged in 8–74% of the forested area, depending on species. These discrepancies affected projections of niche models: for example, 22–75% of the area projected as suitable by at least one model generated using one source of data was not projected as such by all other models. For most species, this proportion increased under scenarios of climate change, whatever the model used. To a lesser extent, uncertainties on current species distributions also affect the validation score of process-based distribution models.
Main conclusions
Reliable, widely used sources of occurrence data strongly diverge even for well-known taxa – the most common European trees. Scientists and stakeholders should acknowledge this gap in knowledge, since accurate data are a prerequisite to providing stakeholders with robust forecasts on biodiversity. Participatory science programmes and remote sensing techniques are promising tools for rapidly gathering such data.
26 Oct 10:01
Choices of abundance currency, community definition and diversity metric control the predictive power of macroecological models of biodiversity
by Grégoire Certain, Carsten F. Dormann, Benjamin Planque
Abstract
Aim
This study focuses on the influence of methodological choices on the predictive performance of macroecological models (MEMs), i.e. statistical models designed to predict patterns of biodiversity using environmental predictors. We emphasize the influence of three methodological choices: (1) the choice of the currency in which the abundance of each species is measured, i.e. numbers of individuals or biomass; (2) the rules used to define the species assemblage under focus, i.e. broad communities or refined ecological guilds; and (3) the influence of rare over common species in the biodiversity measure.
Location
The effects of these choices are investigated using an exhaustive dataset on the fish fauna of the continental shelf of the Barents Sea.
Methods
We conducted an analysis of 220 models resulting from all possible combinations of the three methodological choices. For each, we evaluated the predictive performance through an iterative cross-validation process.
Results
All methodological choices we investigated strongly affected the predictive performance of MEMs. High predictive performances were obtained when using biomass instead of numbers of individuals, when focusing on narrow ecological guilds composed of species sharing the same ecological traits and when using diversity measures that give high weight to rare species.
Main conclusions
We recommend that future projections of biodiversity pay more attention to abundance currency, ecological homogeneity of focal species assemblages and the diversity metric used, and systematically investigate these methodological choices prior to producing biodiversity forecasts. Splitting a whole set of species into ecological guilds appears to be a promising practice, leading to a selected set of MEMs with high predictive performances and more detailed forecasts on the fate of diversity.
24 Oct 17:28
Drivers of richness and density
by Carvalho, G. H., Batalha, M. A.
Environmental filtering prevents species without certain attributes from occurring in local communities. Traits respond differently to different abiotic factors, assembling communities with varying composition along environmental gradients. Here, we measured proxies of soil fertility, disturbance by fire, response and physiological traits to assess how these variables interact to determine woody species richness and density in a Neotropical savannah. We explicitly incorporated our assumptions about how different abiotic filters influence different subsets of traits into a statistical model using structural equation modelling, yielding a more accurate representation of the assembly process. Fire had an effect on resistance traits, whereas soil fertility influenced physiological traits. Resistance traits explained both the richness and density of plots, whereas physiological traits explained only the density. Fewer fire events led to richer and denser plots. Similarly, areas with lower cation exchange capacity assembled less dense communities. Furthermore, we showed that structural equation modelling yielded a realistic representation of the bivariate interactions of distinct environmental filters with different subsets of traits.
24 Oct 17:28
Origin, heat tolerance and range breadth
by Bates, A. E., McKelvie, C. M., Sorte, C. J. B., Morley, S. A., Jones, N. A. R., Mondon, J. A., Bird, T. J., Quinn, G.
Species with broader geographical ranges are expected to be ecological generalists, while species with higher heat tolerances may be relatively competitive at more extreme and increasing temperatures. Thus, both traits are expected to relate to increased survival during transport to new regions of the globe, and once there, establishment and spread. Here, we explore these expectations using datasets of latitudinal range breadth and heat tolerance in freshwater and marine invertebrates and fishes. After accounting for the latitude and hemisphere of each species’ native range, we find that species introduced to freshwater systems have broader geographical ranges in comparison to native species. Moreover, introduced species are more heat tolerant than related native species collected from the same habitats. We further test for differences in range breadth and heat tolerance in relation to invasion success by comparing species that have established geographically restricted versus extensive introduced distributions. We find that geographical range size is positively related to invasion success in freshwater species only. However, heat tolerance is implicated as a trait correlated to widespread occurrence of introduced populations in both freshwater and marine systems. Our results emphasize the importance of formal risk assessments before moving heat tolerant species to novel locations.
24 Oct 17:28
A spatiotemporal pattern analysis of historical mountain pine beetle outbreaks in British Columbia, Canada
by Huapeng Chen
This study documents the spatiotemporal patterns of mountain pine beetle infestations by applying a novel approach based on a landscape infestation dynamics conceptual model in combination with morphological spatial pattern analysis using the mountain pine beetle infested pine mortality data (1960–2010) collected by the annual British Columbia aerial overview survey. The pattern analysis at the provincial level reveals that the 1980s outbreak did not crash as originally thought. The current outbreak is most likely a result of the progressive buildup of the epidemic infestations during the transition period (1985–1995) under favourable weather conditions and substantially improved host resources. This is also true for the Northeast and Cariboo areas of the province specifically, even though the infestations in the Cariboo area remained at incipient-epidemic levels during the transition period after the 1980s outbreak crashed in 1985. In the Southeast area, the current outbreak apparently continued from the outbreak that initiated in the late 1970s and early 1980s. The 1980s outbreak originated from multiple spatially separate locations whereas the current outbreak initiated from a single location in Tweedsmuir Provincial Park. The centralized and self-amplifying buildup of the current outbreak implicates at least three substantial expansions that occurred in 2002, 2006, and 2008. This study suggests that at the provincial level, as well as for the Northeast and Southeast areas of the province, the current outbreak is declining but most likely will continue for many years given the ongoing and future warming climate and a large proportion of pines that remain in the habitats of mountain pine beetles. This study also suggests that dispersals, particularly long-distance dispersal, may play a key role in driving the spread and expansion of the current outbreak although uncertainty remains due to the local dynamics of the beetle populations.
24 Oct 17:28
Scaling of species distribution models across spatial resolutions and extents along a biogeographic gradient. The case of the Iberian mole Talpa occidentalis
by Susana Suárez-Seoane, Emilio Virgós, Olga Terroba, Xosé Pardavila, Jose M. Barea-Azcón
Scaling is a key process in modelling approaches since it allows for translating information from one scale to another. However, the success of this procedure may depend on ‘source’ and ‘target’ scales, but also on the biogeographic/ecological context of the study area. We aimed to quantify the performance and success of scaling species distribution model (SDM) predictions across spatial resolution and extent along a biogeographic gradient using the Iberian mole as study case. We ran separate MaxEnt models at two extents (national and regional) using independent datasets (species locations and environmental predictors) collected at 10 km and 50 m resolutions respectively. Model performance and success of scaling SDMs were quantified on the basis of accuracy measures and spatial predictions. Complementarily, we calculated marginality and tolerance as indicators of habitat availability and niche truncation along the biogeographic gradient. Model performance increased with resolution and extent, as well as from north to south (mainly for high resolution models). When regional models were validated at different scales, their performance reduced severely, particularly in the case of coarse resolution models (some of them performed worse than random). However, when the 10 km-national model was downscaled within regions, it performed better (AUCtest: 0.82, 0.85 and 0.55 respectively for Galicia, Madrid and Granada) than models specifically calibrated within each region at 10 km (0.47, 0.65, 0.44). Indeed, it also had a better accuracy when projected at 50 m (0.77, 0.91, 0.79) than models fitted at that resolution (0.62, 0.83, 0.96) in two of the three cases. The success of scaling model predictions decreased along the biogeographic gradient, being these differences associated to niche truncation. Models representing non-truncated niches were more successfully scaled across resolutions and extents (particularly in areas not offering all possible habitats for species), which has important implications for SDM applications.
24 Oct 17:28
Completeness of digital accessible knowledge of the plants of Brazil and priorities for survey and inventory
by Mariane Silveira Sousa-Baena, Letícia Couto Garcia, Andrew Townsend Peterson
Abstract
Aim
Biodiversity information is the focus of major initiatives aimed at assembling large-scale primary-data documentation (‘digital accessible knowledge’) of the distribution of life on Earth. Recent efforts within Brazil have assembled a massive amount of such documentation for Brazilian plants, which we analyse in this study. Our aim is to identify areas representing gaps in current knowledge; these gaps can guide future botanical exploration and discovery in Brazil.
Location
Brazil.
Methods
We assessed angiosperm inventories across Brazil at diverse spatial scales using statistics that summarize inventory completeness. In particular, we assess the completeness of geographical knowledge of Brazilian floras as measured in terms of geographical distance and climatic difference from well-documented sites.
Results
Spatial knowledge of Brazilian angiosperms is very unevenly distributed: well-known sites are concentrated in eastern and southern regions, whereas the remainder of the country remains poorly documented. Worse still, in many regions, areas lacking detailed botanical documentation coincide with areas of intense habitat destruction, such that many such sites will never be documented scientifically.
Main conclusions
This study illustrates how biodiversity survey and inventory efforts can be guided by existing knowledge. That is, to the extent that existing biodiversity knowledge is made digital and openly available, and to the extent that information is sufficiently comprehensive and informative, spatial summaries of completeness such as that presented here offer clear and strategic directions for maximizing the yield of new knowledge from any de novo field efforts.
24 Oct 17:27
Niche construction and aboriginal fire
by Bird, R. B., Tayor, N., Codding, B. F., Bird, D. W.
Anthropogenic fire is a form of ecosystem engineering that creates greater landscape patchiness at small spatial scales: such rescaling of patch diversity through mosaic burning has been argued to be a form of niche construction, the loss of which may have precipitated the decline and extinction of many endemic species in the Western Desert of Australia. We find evidence to support this hypothesis relative to one keystone species, the sand monitor lizard (Varanus gouldii). Paradoxically, V. gouldii populations are higher where Aboriginal hunting is most intense. This effect is driven by an increase in V. gouldii densities near successional edges, which is higher in landscapes that experience extensive human burning. Over time, the positive effects of patch mosaic burning while hunting overwhelm the negative effects of predation in recently burned areas to produce overall positive impacts on lizard populations. These results offer critical insights into the maintenance of animal communities in the desert, supporting the hypothesis that the current high rate of endemic species decline among small animals may be linked to the interaction between invasive species and mid-century removal of Aboriginal niche construction through hunting and patch mosaic burning.