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08 Feb 21:00

New article: Rewilding: a potential alternative approach to conservation in abandoned mountain areas?

by Lluís Brotons

imageLand-use change is a large component of global change and the effects on biodiversity and ecosystem services currently represent a major challenge for ecologists and conservationists. Several authors have recently suggested that REWILDING may be an appealing conservation response to farmland abandonment in areas of Europe where the social structure of farming communities has been eroded and low-intensity farming is no longer socially or economically viable. ECOLAND group, in collaboration with GRUMETS lab (CREAF and Autonomous University of Barcelona) and University of Santiago de Compostela (USC), have assessed the relative positive and negative effects of land abandonment on Gerês–Xurés Transboundary Biosphere Reserve (NW Iberian Peninsula) in order to quantify the potential conservation costs and benefits of a rewilding as a land-use management policy.

In a first study published in International Journal of Applied Earth Observation and Geoinformation, we aimed to determine if the abandonment of the rural areas was the main driver of landscape dynamics on this particular mountain area, or if other factors, such as wildfires and the land management were also directly affecting these spatio-temporal dynamics. For this purpose, we used earth observation data acquired from Landsat TM and ETM + satellite sensors, complemented by ancillary data and prior field knowledge, to evaluate the land use/land cover changes in our study region over a 10-year period (2000–2010). Our findings showed that rural exodus of the last century, differences in land management and fire suppression policies between Spain and Portugal and the different protection schemes could partly explain the different patterns of changes recorded in these covers.

In a second study, recently accepted in Regional Environmental Change, we investigated the effects of land abandonment processes on bird assemblages at both landscape and local scale. We combined medium-term data on avifauna distribution with information on temporal changes in land-use/land-cover extracted from satellite data. In light of our results, rewilding appears to have overall positive effects on biodiversity and should be considered by policy makers as alternative land-use strategy in marginal mountain areas, particularly if they have been historically affected by wildfires. Fire management aimed at favouring the creation of small burned areas in progressively closed landscapes derived from rewilding may be a complementary alternative to maintain open habitats in these areas.

Regos, A., Ninyerola, M., Moré, G., Pons, X., 2015. Linking land cover dynamics with driving forces in mountain landscape of the Northwestern Iberian Peninsula. Int. J. Appl. Earth Obs. Geoinf. 38, 1–14.

Regos, A., Domínguez, J., Gil-Tena, A., Brotons, L., Ninyerola, M., Pons, X., 2014. Rural abandoned landscapes and bird assemblages: winners and losers in the rewilding of a marginal mountain area (NW Spain). Reg. Environ. Chang.

08 Feb 20:58

2014 issue already online

by Oscar

Click here to see the pdf of all the papers
28 Jun 16:06

The gliding speed of migrating birds: slow and safe or fast and risky?

by Nir Horvitz, Nir Sapir, Felix Liechti, Roni Avissar, Isaac Mahrer, Ran Nathan


Aerodynamic theory postulates that gliding airspeed, a major flight performance component for soaring avian migrants, scales with bird size and wing morphology. We tested this prediction, and the role of gliding altitude and soaring conditions, using atmospheric simulations and radar tracks of 1346 birds from 12 species. Gliding airspeed did not scale with bird size and wing morphology, and unexpectedly converged to a narrow range. To explain this discrepancy, we propose that soaring-gliding birds adjust their gliding airspeed according to the risk of grounding or switching to costly flapping flight. Introducing the Risk Aversion Flight Index (RAFI, the ratio of actual to theoretical risk-averse gliding airspeed), we found that inter- and intraspecific variation in RAFI positively correlated with wing loading, and negatively correlated with convective thermal conditions and gliding altitude, respectively. We propose that risk-sensitive behaviour modulates the evolution (morphology) and ecology (response to environmental conditions) of bird soaring flight.

28 Jun 16:05

How context dependent are species interactions?

by Scott A. Chamberlain, Judith L. Bronstein, Jennifer A. Rudgers


The net effects of interspecific species interactions on individuals and populations vary in both sign (−, 0, +) and magnitude (strong to weak). Interaction outcomes are context-dependent when the sign and/or magnitude change as a function of the biotic or abiotic context. While context dependency appears to be common, its distribution in nature is poorly described. Here, we used meta-analysis to quantify variation in species interaction outcomes (competition, mutualism, or predation) for 247 published articles. Contrary to our expectations, variation in the magnitude of effect sizes did not differ among species interactions, and while mutualism was most likely to change sign across contexts (and predation least likely), mutualism did not strongly differ from competition. Both the magnitude and sign of species interactions varied the most along spatial and abiotic gradients, and least as a function of the presence/absence of a third species. However, the degree of context dependency across these context types was not consistent among mutualism, competition and predation studies. Surprisingly, study location and ecosystem type varied in the degree of context dependency, with laboratory studies showing the highest variation in outcomes. We urge that studying context dependency per se, rather than focusing only on mean outcomes, can provide a general method for describing patterns of variation in nature.

28 Jun 16:05

Ecological traits influence the phylogenetic structure of bird species co-occurrences worldwide

by Jean-Yves Barnagaud, W. Daniel Kissling, Brody Sandel, Wolf L. Eiserhardt, Çağan H. Şekercioğlu, Brian J. Enquist, Constantinos Tsirogiannis, Jens-Christian Svenning


The extent to which species’ ecological and phylogenetic relatedness shape their co-occurrence patterns at large spatial scales remains poorly understood. By quantifying phylogenetic assemblage structure within geographic ranges of >8000 bird species, we show that global co-occurrence patterns are linked – after accounting for regional effects – to key ecological traits reflecting diet, mobility, body size and climatic preference. We found that co-occurrences of carnivorous, migratory and cold-climate species are phylogenetically clustered, whereas nectarivores, herbivores, frugivores and invertebrate eaters tend to be more phylogenetically overdispersed. Preference for open or forested habitats appeared to be independent from the level of phylogenetic clustering. Our results advocate for an extension of the tropical niche conservatism hypothesis to incorporate ecological and life-history traits beyond the climatic niche. They further offer a novel species-oriented perspective on how biogeographic and evolutionary legacies interact with ecological traits to shape global patterns of species coexistence in birds.

28 Jun 16:05

Temporal variability of forest communities: empirical estimates of population change in 4000 tree species

by Ryan A. Chisholm, Richard Condit, K. Abd. Rahman, Patrick J. Baker, Sarayudh Bunyavejchewin, Yu-Yun Chen, George Chuyong, H. S. Dattaraja, Stuart Davies, Corneille E. N. Ewango, C. V. S. Gunatilleke, I. A. U. Nimal Gunatilleke, Stephen Hubbell, David Kenfack, Somboon Kiratiprayoon, Yiching Lin, Jean-Remy Makana, Nantachai Pongpattananurak, Sandeep Pulla, Ruwan Punchi-Manage, Raman Sukumar, Sheng-Hsin Su, I-Fang Sun, H. S. Suresh, Sylvester Tan, Duncan Thomas, Sandra Yap


Long-term surveys of entire communities of species are needed to measure fluctuations in natural populations and elucidate the mechanisms driving population dynamics and community assembly. We analysed changes in abundance of over 4000 tree species in 12 forests across the world over periods of 6–28 years. Abundance fluctuations in all forests are large and consistent with population dynamics models in which temporal environmental variance plays a central role. At some sites we identify clear environmental drivers, such as fire and drought, that could underlie these patterns, but at other sites there is a need for further research to identify drivers. In addition, cross-site comparisons showed that abundance fluctuations were smaller at species-rich sites, consistent with the idea that stable environmental conditions promote higher diversity. Much community ecology theory emphasises demographic variance and niche stabilisation; we encourage the development of theory in which temporal environmental variance plays a central role.

28 Jun 16:04

Urbanisation tolerance and the loss of avian diversity

by Daniel Sol, Cesar González-Lagos, Darío Moreira, Joan Maspons, Oriol Lapiedra


Urbanisation is considered an important driver of current biodiversity loss, but the underlying causes are not fully understood. It is generally assumed that this loss reflects the fact that most organisms do not tolerate well the environmental alterations associated with urbanisation. Nevertheless, current evidence is inconclusive and the alternative that the biodiversity loss is the result of random mechanisms has never been evaluated. Analysing changes in abundance between urbanised environments and their non-urbanised surroundings of > 800 avian species from five continents, we show here that although random processes account for part of the species loss associated with urbanisation, much of the loss is associated with a lack of appropriate adaptations of most species for exploiting resources and avoiding risks of the urban environments. These findings have important conservation implications because the extinction of species with particular features should have higher impact on biodiversity and ecosystem function than a random loss.

07 Jun 12:34

Frugivores at higher risk of extinction are the key elements of a mutualistic network

by (Mariana Morais Vidal)
Ecology, Ahead of Print.
Most tree species rely on vertebrates for seed dispersal, and many vertebrates use fruits as food resources in tropical forests. Therefore, plant-frugivore interactions affect population dynamics and persistence in ecological communities. Plant-frugivore interactions often involve many species, forming networks of interacting plants and animals that play different roles in determining network organization. The network organization is the way interactions are structured in the community, which may have consequences on its ecological and evolutionary dynamics. Some species have greater influences on network organization and may be particularly important to species persistence. We identified the frugivores most important to the organization of networks of plants and frugivorous birds in three contiguous Atlantic forest sites in Southeastern Brazil. We found that species that contributed most to network organization were at higher risk of extinction. Among the main contributors to network organization were two cotingas and a toucan, large-bodied species that disperse seeds from many plants and are particularly vulnerable to habitat loss and hunting. As a consequence, ongoing extinctions may significantly affect the organization of plant-frugivore interactions in the studied system. We hypothesize the crucial role of some threatened frugivores may occur in other seed dispersal systems in tropical communities, although the association between structural importance and degree of threat may be contingent on peculiarities of local communities and disturbances.
10 May 20:59

Unifying niche shift studies: insights from biological invasions

Antoine Guisan, Blaise Petitpierre, Olivier Broennimann, Curtis Daehler, Christoph Kueffer.
• We propose a unifying framework for assessing niche shifts from empirical data.
• We base it on a review of studies of niche changes during biological invasions.
10 May 20:57

Fire severity and tree regeneration following bark beetle outbreaks: the role of outbreak stage and burning conditions

by (Brian J. Harvey et al)
Ecological Applications, Ahead of Print.
The degree to which recent bark beetle (Dendroctonus ponderosae) outbreaks may influence fire severity and post-fire tree regeneration is of heightened interest to resource managers throughout western North America, but empirical data on actual fire effects are lacking. Outcomes may depend on burning conditions (i.e., weather during fire), outbreak severity, or intervals between outbreaks and subsequent fire. We studied recent fires that burned through green-attack / red-stage (outbreaks
10 May 20:57

Agreed but not preferred: expert views on taboo options for biodiversity conservation, given climate change

by (Shannon M. Hagerman et al)
Ecological Applications, Volume 24, Issue 3, Page 548-559, April 2014.
Recent research indicates increasing openness among conservation experts toward a set of previously controversial proposals for biodiversity protection. These include actions such as assisted migration, and the application of climate-change-informed triage principles for decision-making (e.g., forgoing attention to target species deemed no longer viable). Little is known however, about the levels of expert agreement across different conservation adaptation actions, or the preferences that may come to shape policy recommendations. In this paper, we report findings from a web-based survey of biodiversity experts that assessed: (1) perceived risks of climate change (and other drivers) to biodiversity, (2) relative importance of different conservation goals, (3) levels of agreement/disagreement with the potential necessity of unconventional-taboo actions and approaches including affective evaluations of these, (4) preferences regarding the most important adaptation action for biodiversity, and (5) perceived barriers and strategic considerations regarding implementing adaptation initiatives. We found widespread agreement with a set of previously contentious approaches and actions, including the need for frameworks for prioritization and decision-making that take expected losses and emerging novel ecosystems into consideration. Simultaneously, this survey found enduring preferences for conventional actions (such as protected areas) as the most important policy action, and negative affective responses toward more interventionist proposals. We argue that expert views are converging on agreement across a set of taboo components in ways that differ from earlier published positions, and that these views are tempered by preferences for existing conventional actions and discomfort toward interventionist options. We discuss these findings in the context of anticipating some of the likely contours of future conservation debates. Lastly, we underscore the critical need for interdisciplinary, comparative, place-based adaptation research.
10 May 20:56

Fuel treatments and landform modify landscape patterns of burn severity in an extreme fire event

by (Susan J. Prichard et al)
Ecological Applications, Volume 24, Issue 3, Page 571-590, April 2014.
Under a rapidly warming climate, a critical management issue in semiarid forests of western North America is how to increase forest resilience to wildfire. We evaluated relationships between fuel reduction treatments and burn severity in the 2006 Tripod Complex fires, which burned over 70 000 ha of mixed-conifer forests in the North Cascades range of Washington State and involved 387 past harvest and fuel treatment units. A secondary objective was to investigate other drivers of burn severity including landform, weather, vegetation characteristics, and a recent mountain pine beetle outbreak. We used sequential autoregression (SAR) to evaluate drivers of burn severity, represented by the relative differenced Normalized Burn Ratio index, in two study areas that are centered on early progressions of the wildfire complex. Significant predictor variables include treatment type, landform (elevation), fire weather (minimum relative humidity and maximum temperature), and vegetation characteristics, including canopy closure, cover type, and mountain pine beetle attack. Recent mountain pine beetle damage was a statistically significant predictor variable with red and mixed classes of beetle attack associated with higher burn severity. Treatment age and size were only weakly correlated with burn severity and may be partly explained by the lack of treatments older than 30 years and the low rates of fuel succession in these semiarid forests. Even during extreme weather, fuel conditions and landform strongly influenced patterns of burn severity. Fuel treatments that included recent prescribed burning of surface fuels were particularly effective at mitigating burn severity. Although surface and canopy fuel treatments are unlikely to substantially reduce the area burned in regional fire years, recent research, including this study, suggests that they can be an effective management strategy for increasing forest landscape resilience to wildfires.
10 May 20:56

Assessing migratory connectivity for a long-distance migratory bird using multiple intrinsic markers

by (Clark S. Rushing et al)
Ecological Applications, Volume 24, Issue 3, Page 445-456, April 2014.
Patterns of migratory connectivity are a vital yet poorly understood component of the ecology and evolution of migratory birds. Our ability to accurately characterize patterns of migratory connectivity is often limited by the spatial resolution of the data, but recent advances in probabilistic assignment approaches have begun pairing stable isotopes with other sources of data (e.g., genetic and mark–recapture) to improve the accuracy and precision of inferences based on a single marker. Here, we combine stable isotopes and geographic variation in morphology (wing length) to probabilistically assign Wood Thrush (Hylocichla mustilena) captured on the wintering grounds to breeding locations. In addition, we use known-origin samples to validate our model and assess potentially important impacts of isotopic and morphological covariates (age, sex, and breeding location). Our results show that despite relatively high levels of mixing across their breeding and nonbreeding ranges, moderate levels of migratory connectivity exist along an east–west gradient. In addition, combining stable isotopes with geographic variation in wing length improved the precision of breeding assignments by 10% and 37% compared to assignments based on isotopes alone or wing length alone, respectively. These results demonstrate that geographical variation in morphological traits can greatly improve estimates of migratory connectivity when combined with other intrinsic markers (e.g., stable isotopes or genetic data). The wealth of morphological data available from museum specimens across the world represents a tremendously valuable, but largely untapped, resource that is widely applicable for quantifying patterns of migratory connectivity.
10 May 20:56

Disturbance legacies increase the resilience of forest ecosystem structure, composition, and functioning

by (Rupert Seidl et al)
Ecological Applications, Ahead of Print.
Disturbances are key drivers of forest ecosystem dynamics, and forests are well adapted to their natural disturbance regimes. However, as a result of climate change, disturbance frequency is expected to increase in the future in many regions. It is not yet clear how such changes might affect forest ecosystems, and which mechanisms contribute to (current and future) disturbance resilience. We studied a 6364-ha landscape in the western Cascades of Oregon, USA, to investigate how patches of remnant old-growth trees (as one important class of biological legacies) affect the resilience of forest ecosystems to disturbance. Using the spatially explicit, individual-based forest landscape model iLand we analyzed the effect of three different levels of remnant patches (0%, 12%, and 24% of the landscape) on 500-year recovery trajectories after a large, high severity wildfire. In addition, we evaluated how three different levels of fire frequency modulate the effects of initial legacies. We found that remnant live trees enhanced the recovery of total ecosystem carbon (TEC) stocks after disturbance, increased structural complexity of forest canopies, and facilitated the recolonization of late-seral species (LSS). Legacy effects were most persistent for indicators of species composition (still significant 500 years after disturbance), while TEC (i.e., a measure of ecosystem functioning) was least affected, with no significant differences among legacy scenarios after 236 years. Compounding disturbances were found to dampen legacy effects on all indicators, and higher initial legacy levels resulted in elevated fire severity in the second half of the study period. Overall, disturbance frequency had a stronger effect on ecosystem properties than the initial level of remnant old-growth trees. A doubling of the historically observed fire frequency to a mean fire return interval of 131 years reduced TEC by 10.5% and lowered the presence of LSS on the landscape by 18.1% on average, demonstrating that an increase in disturbance frequency (a potential climate change effect) may considerably alter the structure, composition, and functioning of forest landscapes. Our results indicate that live tree legacies are an important component of disturbance resilience, underlining the potential of retention forestry to address challenges in ecosystem management.
10 May 20:55

Functional connectivity experiments reflect routine movement behavior of a tropical hummingbird species

by (Noelia Laura Volpe et al)
Ecological Applications, Ahead of Print.
Translocation experiments, in which researchers displace animals then monitor their movements to return home, are commonly used as tools to assess functional connectivity of fragmented landscapes. Such experiments are purported to have important advantages of being time efficient and standardizing 'motivation' to move across individuals. Yet, we lack tests of whether movement behavior of translocated birds reflects natural behavior of unmanipulated birds. We compared the routine movement behavior of a tropical hummingbird (Phaethornis guy) to that of experimentally translocated individuals. We tested for differences in site-selection patterns during movement at two spatial scales (point and path levels). We also compared movement rates between treatments. Behaviors documented during translocation experiments reflected those observed during routine movements. At the point level, both translocated and non-translocated birds showed similar levels of preference for mature tropical forest. At the path level, step selection functions showed both translocated and non-translocated hummingbirds avoiding movement across non-forested matrix and selecting streams as movement corridors. Movement rates were generally higher during translocation experiments. However, the negative influence of forest cover on movement rates was proportionately similar in translocation and routine movement treatments. We report the first evidence showing that movement behavior of birds during translocation experiments is similar to their natural movement behavior. Therefore, translocation experiments may be reliable tools to address effects of landscape structure on animal movement. We observed consistent selection of landscape elements between translocated and non-translocated birds, indicating that both routine and translocation movement studies lead to similar conclusions regarding the effect of landscape structure and forest composition on functional connectivity. Our observations that hummingbirds avoid non-forest matrix and select riparian corridors also provides a potential mechanism for pollen limitation in fragmented tropical forest.
10 May 20:55

Biomass growth response to spatial pattern of variable retention harvesting in a northern Minnesota pine ecosystem

by (Brian J. Palik et al)
Ecological Applications, Ahead of Print.
Variable retention harvesting (VRH) is an approach for sustaining complex structure in managed forests. A criticism of VRH is that ecological benefits may come at a cost of reduced growth of regeneration, due to competition with residual trees. However, the spatial pattern of retention, i.e., dispersed or aggregated, in VRH systems can be manipulated to minimize suppression of regeneration, and resource limitation to regeneration might be mitigated by reduction of woody shrubs. Continued growth of the residual cohort will compensate for growth reduction of regeneration, although this may differ with retention pattern. We examined above-ground whole-stand biomass growth of trees in a VRH experiment in Pinus resinosa forest in Minnesota, USA. Treatments included dispersed retention, aggregated retention, and an uncut control, as well as a shrub treatment (reduced density or ambient). We addressed the following hypotheses: 1) biomass growth of a cohort of planted pine seedlings will be highest with aggregated rather than dispersed retention; 2) biomass growth of the planted seedlings will increase with shrub reduction; and 3) biomass growth of the residual overstory will be higher with dispersed rather than aggregated retention. Above-ground biomass growth of the planted pines ranged from 0.4 kg ha-1 yr-1 in the overstory control-ambient shrub treatment to 23 kg ha-1 yr-1 in the aggregated retention-shrub reduction treatment. The difference between the control and the retention treatments was significant (p100% increase) with shrub reduction (p=0.001), supporting our second hypothesis. Biomass growth of residual trees ranged from 2404 kg ha-1 yr-1 in the uncut control-ambient shrub treatment to 1043 kg ha-1 yr-1 in the aggregated retention-shrub reduction treatment. Differences were significant between the control and retention treatments (p=0.003), and marginally higher with dispersed versus aggregated retention (p=0.09), lending support to our third hypothesis. Our results suggest that managers have flexibility in application of VRH and can expect similar stand-level biomass growth of planted regeneration regardless of retention pattern, but somewhat higher stand-level biomass growth of retained trees with dispersed retention.
10 May 20:55

Aboveground biomass mapping of African forest mosaics using canopy texture analysis: towards a regional approach.

by (Jean-François Bastin et al)
Ecological Applications, Ahead of Print.
In the context of the reduction of greenhouse gas emissions caused by deforestation and forest degradation (the REDD+ program), optical very high resolution (VHR) satellite images provide an opportunity to characterize forest canopy structure and to quantify aboveground biomass (AGB) at less expense than methods based on airborne remote sensing data. Among the methods for processing these VHR images, Fourier textural ordination (FOTO) presents a good potential to detect forest canopy structural heterogeneity and therefore to predict AGB variations. Notably, the method does not saturate at intermediate AGB values as do pixelwise processing of available space borne optical and radar signals. However, a regional scale application requires to overcome two difficulties: (i) instrumental effects due to variations in sun-scene-sensor geometry or sensor-specific responses that preclude the use of wide arrays of images acquired under heterogeneous conditions and (ii) forest structural diversity including monodominant or open canopy forests, which are of particular importance in Central Africa. In this study, we demonstrate the feasibility of a rigorous regional study of canopy texture by harmonizing FOTO indices of images acquired from two different sensors (Geoeye-1 and QuickBird-2) and different sun-scene-sensor geometries and by calibrating a piecewise biomass inversion model using 26 inventory plots (1 ha) sampled across very heterogeneous forest types. A good agreement was found between observed and predicted AGB (RSE=15%; R²=0.85; p-value
10 May 20:55

Effects of Forest Management on California Spotted Owls: Implications for Reducing Wildfire Risk in Fire-prone Forests

by (Douglas Tempel et al)
Ecological Applications, Ahead of Print.
Management of many North American forests is challenged by the need to balance the potentially competing objectives of reducing risks posed by high-severity wildfires and protecting threatened species. In the Sierra Nevada, California, concern about high-severity fires has increased in recent decades but uncertainty exists over the effects of fuel-reduction treatments on old-growth associated species such as the California spotted owl (Strix occidentalis occidentalis). Here, we assessed the effects of forest conditions, fuel reductions, and wildfire on a declining population of spotted owls in the central Sierra Nevada using 20 years of demographic data collected at 74 spotted owl territories. Adult survival and territory colonization were relatively high, while territory extinction was relatively low, in territories that had greater amounts of high-canopy forest ({greater than or equal to}70% cover). Reproductive output was negatively associated with the area of medium-intensity timber harvests characteristic of proposed fuel treatments. Our results also suggest that the amount of edge between older forests and shrub/sapling vegetation and increased habitat heterogeneity may result in higher spotted owl demographic rates. Finally, high-severity fire reduced the likelihood of colonization of unoccupied territories. Despite correlations between owl demographic rates and several habitat variables, life-stage simulation (sensitivity) analyses indicated that the amount of high-canopy forest was the primary driver of population growth and equilibrium occupancy at the territory scale. Greater than 90% of medium-intensity harvests converted high-canopy forests into lower-canopy vegetation classes, suggesting that landscape-scale fuel treatments in such stands could have short-term negative impacts on California spotted owl populations. Moreover, high-canopy forests declined by an average of 7.4% across territories during our study, suggesting that habitat loss could have contributed to declines in abundance and territory occupancy detected in a previous study of this population. Thus, we recommend that managers consider the existing amount and spatial distribution of high-canopy forest before implementing fuel treatments within an owl territory and that treatments be accompanied by a rigorous monitoring program within an adaptive management framework.
10 May 20:55

Is US climatic diversity well represented within the existing federal protection network?

by (Enric Batllori et al)
Ecological Applications, Ahead of Print.
Establishing protection networks to ensure that biodiversity and associated ecosystem services persist under changing environments is a major challenge for conservation planning. The potential consequences of altered climates for the structure and function of ecosystems necessitates new and complementary approaches be incorporated into traditional conservation plans. The conterminous United States of America (CONUS) has an extensive system of protected areas managed by federal agencies, but a comprehensive assessment of how this network represents the CONUS climate is lacking. We present a quantitative classification of the climate space that is independent from the geographic locations of climatic observations to evaluate the climatic representation of the existing protected area network. We use this classification to evaluate the coverage of each agency's jurisdiction and to identify current conservation deficits. Our findings reveal that the existing network poorly represents the CONUS climatic diversity. Although rare climates are generally well represented within the network, the most common climates are particularly underrepresented. Overall, 83% of the area of the CONUS corresponds to climates underrepresented by the network. The addition of some currently unprotected federal lands to the network would enhance the coverage of the CONUS climates. However, to fully palliate current conservation deficits, large-scale private-land conservation initiatives will be critical.
28 Apr 15:21

Migration promotes bird diversification

by Rolland, J., Jiguet, F., Jonsson, K. A., Condamine, F. L., Morlon, H.

How seasonal migration originated and impacted diversification in birds remains largely unknown. Although migratory behaviour is likely to affect bird diversification, previous studies have not detected any effect. Here, we infer ancestral migratory behaviour and the effect of seasonal migration on speciation and extinction dynamics using a complete bird tree of life. Our analyses infer that sedentary behaviour is ancestral, and that migratory behaviour evolved independently multiple times during the evolutionary history of birds. Speciation of a sedentary species into two sedentary daughter species is more frequent than speciation of a migratory species into two migratory daughter species. However, migratory species often diversify by generating a sedentary daughter species in addition to the ancestral migratory one. This leads to an overall higher migratory speciation rate. Migratory species also experience lower extinction rates. Hence, although migratory species represent a minority (18.5%) of all extant birds, they have a higher net diversification rate than sedentary species. These results suggest that the evolution of seasonal migration in birds has facilitated diversification through the divergence of migratory subpopulations that become sedentary, and illustrate asymmetrical diversification as a mechanism by which diversification rates are decoupled from species richness.

28 Apr 15:20

Unintended Cultivation, Shifting Baselines, and Conflict between Objectives for Fisheries and Conservation



The effects of fisheries on marine ecosystems, and their capacity to drive shifts in ecosystem states, have been widely documented. Less well appreciated is that some commercially valuable species respond positively to fishing-induced ecosystem change and can become important fisheries resources in modified ecosystems. Thus, the ecological effects of one fishery can unintentionally increase the abundance and productivity of other fished species (i.e., cultivate). We reviewed examples of this effect in the peer-reviewed literature. We found 2 underlying ecosystem drivers of the effect: trophic release of prey species when predators are overfished and habitat change. Key ecological, social, and economic conditions required for one fishery to unintentionally cultivate another include strong top–down control of prey by predators, the value of the new fishery, and the capacity of fishers to adapt to a new fishery. These unintended cultivation effects imply strong trade-offs between short-term fishery success and conservation efforts to restore ecosystems toward baseline conditions because goals for fisheries and conservation may be incompatible. Conflicts are likely to be exacerbated if fisheries baselines shift relative to conservation baselines and there is investment in the new fishery. However, in the long-term, restoration toward ecosystem baselines may often benefit both fishery and conservation goals. Unintended cultivation can be identified and predicted using a combination of time-series data, dietary studies, models of food webs, and socioeconomic data. Identifying unintended cultivation is necessary for management to set compatible goals for fisheries and conservation.

Cultivo Accidental, Líneas de Base Cambiantes y el Conflicto entre los Objetivos para las Pesquerías y la Conservación


Los efectos de la pesca sobre los ecosistemas marinos y su capacidad para conducir cambios en el estado de los ecosistemas han sido documentados ampliamente. Se aprecia menos que algunas especies con valor comercial responden positivamente a cambios en ecosistemas inducidos por la pesca y pueden volverse recursos pesqueros importantes en ecosistemas modificados. Así, los efectos ecológicos de una pesquería pueden incrementar accidentalmente la abundancia y la productividad de otras especies pescadas (p. ej.: cultivar). Revisamos ejemplos de este efecto en la literatura revisada por pares. Encontramos dos conductores de ecosistemas subyacentes del efecto: la liberación trófica de las especies depredadas cuando los depredadores son sobre-pescados y el cambio de hábitat. Las condiciones ecológicas, sociales y económicas clave requeridas para que más de una pesquería cultive accidentalmente a otra incluyeron el control jerárquico fuerte de la presa por los depredadores, el valor de una nueva pesquera y la capacidad de los pescadores para adaptarse a una nueva pesquera. Estos efectos accidentales del cultivo implican fuertes pros y contras entre el éxito pesquero a corto plazo y los esfuerzos de conservación para restaurar ecosistemas a las condiciones de línea base porque los objetivos de las pesqueras y de la conservación pueden ser incompatibles. Los conflictos probablemente sean exacerbados si las líneas base de las pesquerías cambian en relación a las líneas base de la conservación y hay inversión en la nueva pesquería. Sin embargo, a largo plazo, la restauración hacia las líneas base de los ecosistemas puede beneficiar a los objetivos de la pesquería y de la conservación. El cultivo accidental puede identificarse y pronosticarse usando una combinación de datos de series de tiempo, estudios de dieta, modelos de redes alimentarias y datos socioeconómicos. La identificación del cultivo accidental es necesaria para que el manejo ponga objetivos compatibles para las pesquerías y la conservación.

28 Apr 15:19

The Role of Civil Society in Recalibrating Conservation Science Incentives

28 Apr 15:19

Meta-Analysis of the Effects of Forest Fragmentation on Interspecific Interactions



Forest fragmentation dramatically alters species persistence and distribution and affects many ecological interactions among species. Recent studies suggest that mutualisms, such as pollination and seed dispersal, are more sensitive to the negative effects of forest fragmentation than antagonisms, such as predation or herbivory. We applied meta-analytical techniques to evaluate this hypothesis and quantified the relative contributions of different components of the fragmentation process (decreases in fragment size, edge effects, increased isolation, and habitat degradation) to the overall effect. The effects of fragmentation on mutualisms were primarily driven by habitat degradation, edge effects, and fragment isolation, and, as predicted, they were consistently more negative on mutualisms than on antagonisms. For the most studied interaction type, seed dispersal, only certain components of fragmentation had significant (edge effects) or marginally significant (fragment size) effects. Seed size modulated the effect of fragmentation: species with large seeds showed stronger negative impacts of fragmentation via reduced dispersal rates. Our results reveal that different components of the habitat fragmentation process have varying impacts on key mutualisms. We also conclude that antagonistic interactions have been understudied in fragmented landscapes, most of the research has concentrated on particular types of mutualistic interactions such as seed dispersal, and that available studies of interspecific interactions have a strong geographical bias (arising mostly from studies carried out in Brazil, Chile, and the United States).

Meta-Análisis de los Efectos de la Fragmentación del Bosque sobre las Interacciones Interespecíficas


La fragmentación del bosque altera dramáticamente la persistencia y distribución de las especies y afecta a muchas interacciones ecológicas entre las mismas. Estudios recientes sugieren que los mutualismos, como la polinización y la dispersión de semillas, son más sensibles a los efectos negativos de la fragmentación del bosque que los antagonismos, como la depredación y la herbivoría. Aplicamos técnicas de meta-análisis para evaluar esta hipótesis y cuantificamos las contribuciones relativas de los componentes diferentes del proceso de fragmentación (disminuciones en el tamaño de fragmento, efectos de borde, aislamiento incrementado y degradación de hábitat) al efecto total. Los efectos de la fragmentación sobre los mutualismos fueron conducidos principalmente por la degradación del hábitat, los efectos de borde y el aislamiento de fragmentos y, como se predijo, fueron más negativos consecuentemente sobre los mutualismos que sobre los antagonismos. Para el tipo de interacción más estudiado, dispersión de semillas, sólo ciertos componentes de la fragmentación tuvieron efectos significativos (efecto de borde) o significativos marginalmente (tamaño de fragmento). El tamaño de la semilla moduló el efecto de la fragmentación: las especies con semillas grandes mostraron impactos de fragmentación negativos más fuertes por medio de las tasas de dispersión. Nuestros resultados revelan que los componentes diferentes del proceso de fragmentación de hábitat han sido poco estudiados en paisajes fragmentados, que la mayoría de las investigaciones se han concentrado en tipos particulares de interacciones mutualistas como la dispersión de semillas, y que los estudios disponibles de interacciones interespecíficas tienen una parcialidad geográfica fuerte (surgiendo principalmente de estudios llevados a cabo en Brasil, Chile y los Estados Unidos).

27 Apr 16:23

Anticipating the spatio-temporal response of plant diversity and vegetation structure to climate and land use change in a protected area

by Isabelle Boulangeat, Damien Georges, Cédric Dentant, Richard Bonet, Jérémie Van Es, Sylvain Abdulhak, Niklaus E. Zimmermann, Wilfried Thuiller

Vegetation is a key driver of ecosystem functioning (e.g. productivity and stability) and of the maintenance of biodiversity (e.g. creating habitats for other species groups). While vegetation sensitivity to climate change has been widely investigated, its spatio-temporally response to the dual effects of land management and climate change has been ignored at landscape scale. Here we use a dynamic vegetation model called FATE-HD, which describes the dominant vegetation dynamics and associated functional diversity, in order to anticipate vegetation response to climate and land-use changes in both short and long-term perspectives. Using three contrasted management scenarios for the Ecrins National Park (French Alps) developed in collaboration with the park managers, and one regional climate change scenario, we tracked the dynamics of vegetation structure (forest expansion) and functional diversity over 100 yr of climate change and a further 400 additional years of stabilization. As expected, we observed a slow upward shift in forest cover distribution, which appears to be severely impacted by pasture management (i.e. maintenance or abandonment). The time lag before observing changes in vegetation cover was the result of demographic and seed dispersal processes. However, plant diversity response to environmental changes was rapid. After land abandonment, local diversity increased and spatial turnover was reduced, whereas local diversity decreased following land use intensification. Interestingly, in the long term, as both climate and management scenarios interacted, the regional diversity declined. Our innovative spatio-temporally explicit framework demonstrates that the vegetation may have contrasting responses to changes in the short and the long term. Moreover, climate and land-abandonment interact extensively leading to a decrease in both regional diversity and turnover in the long term. Based on our simulations we therefore suggest a continuing moderate intensity pasturing to maintain high levels of plant diversity in this system.

27 Apr 16:22

Biodiversity declines due to abandonment and intensification of agricultural lands: patterns and mechanisms

by (Kei Uchida et al)
Ecological Monographs, Ahead of Print.
Declines in plants and herbivorous insects due to land-use abandonment and intensification, have been studied in agricultural areas worldwide. We tested four hypotheses, which were complementary rather than mutually exclusive, to understand the mechanisms driving biodiversity decline due to abandonment and intensification. These predict that biodiversity decline is caused by a decline in resource diversity, changes in disturbance regime, surrounding landscape conversion and a decrease in biomass production. We compared plant richness and butterfly and orthopteran richness and diversity among three land-use types in semi-natural grasslands: abandoned, traditional, and intensified terraces. Then, we examined effects of changes in resource (plant) richness, frequency of disturbance (mowing), and surrounding landscapes on butterfly and orthopteran diversity to understand the mechanisms driving decline after land abandonment and intensification. Plant and herbivore richness and diversity were significantly lower in abandoned and intensified grasslands than in traditional grasslands. This trend was consistent throughout the seasons in both years of study. Changes in mowing frequency and the surrounding landscape explained plant richness decline as a consequence of land abandonment and intensification. Declines in herbivorous insects were explained by plant richness declines and changes in mowing frequency but not by landscape changes. Plant and herbivore richness were maximized at an intermediate mowing frequency (ca. twice per year), which is typical practice on traditional terraces. This is the first report demonstrating that the intermediate disturbance hypothesis well explained the biodiversity declines in agricultural ecosystems. The richness and diversity responses of herbivore functional groups to plant richness, mowing frequency, and surrounding landscapes were generally inconsistent with predictions. We found significant trends in which butterfly and orthopteran species with low abundance in traditional terraces were lost in abandoned and/or intensive terraces. This may suggest that the number of individuals of most herbivorous species decreased randomly with respect to life-history traits following a decline in plant richness after changes in disturbance frequency. This study demonstrates that declines in herbivorous insects can be explained by multiple factors and provides a unified explanation for biodiversity decline in both abandoned and intensified of agricultural lands, which have often been studied separately.
15 Apr 20:52

Using dynamic vegetation models to simulate plant range shifts

by R. S. Snell, A. Huth, J. E. M. S. Nabel, G. Bocedi, J. M. J. Travis, D. Gravel, H. Bugmann, A. G. Gutiérrez, T. Hickler, S. I. Higgins, B. Reineking, M. Scherstjanoi, N. Zurbriggen, H. Lischke

Dynamic vegetation models (DVMs) follow a process-based approach to simulate plant population demography, and have been used to address questions about disturbances, plant succession, community composition, and provisioning of ecosystem services under climate change scenarios. Despite their potential, they have seldom been used for studying species range dynamics explicitly. In this perspective paper, we make the case that DVMs should be used to this end and can improve our understanding of the factors that influence species range expansions and contractions. We review the benefits of using process-based, dynamic models, emphasizing how DVMs can be applied specifically to questions about species range dynamics. Subsequently, we provide a critical evaluation of some of the limitations and trade-offs associated with DVMs, and we use those to guide our discussions about future model development. This includes a discussion on which processes are lacking, specifically a mechanistic representation of dispersal, inclusion of the seedling stage, trait variability, and a dynamic representation of reproduction. We also discuss upscaling techniques that offer promising solutions for being able to run these models efficiently over large spatial extents. Our aim is to provide directions for future research efforts and to illustrate the value of the DVM approach.

15 Apr 20:52

Latitudinal gradients in butterfly population variability are influenced by landscape heterogeneity

by Tom H. Oliver, Constanti Stefanescu, Ferran Páramo, Tom Brereton, David B. Roy

The variability of populations over time is positively associated with their risk of local extinction. Previous work has shown that populations at the high-latitude boundary of species’ ranges show higher inter-annual variability, consistent with increased sensitivity and exposure to adverse climatic conditions. However, patterns of population variability at both high- and low-latitude species range boundaries have not yet been concurrently examined. Here, we assess the inter-annual population variability of 28 butterfly species between 1994 and 2009 at 351 and 18 sites in the United Kingdom and Catalonia, Spain, respectively. Local population variability is examined with respect to the position of the species’ bioclimatic envelopes (i.e. whether the population falls within areas of the ‘core’ climatic suitability or is a climatically ‘marginal’ population), and in relation to local landscape heterogeneity, which may influence these range location – population dynamic relationships. We found that butterfly species consistently show latitudinal gradients in population variability, with increased variability in the more northerly UK. This pattern is even more marked for southerly distributed species with ‘marginal’ climatic suitability in the UK but ‘core’ climatic suitability in Catalonia. In addition, local landscape heterogeneity did influence these range location – population dynamic relationships. Habitat heterogeneity was associated with dampened population dynamics, especially for populations in the UK. Our results suggest that promoting habitat heterogeneity may promote the persistence of populations at high-latitude range boundaries, which may potentially aid northwards expansion under climate warming. We did not find evidence that population variability increases towards southern range boundaries. Sample sizes for this region were low, but there was tentative evidence, in line with previous ecological theory, that local landscape heterogeneity may promote persistence in these retracting low-latitude range boundary populations.

15 Apr 20:51

Can site and landscape-scale environmental attributes buffer bird populations against weather events?

by Stuart E. Newson, Tom H. Oliver, Simon Gillings, Humphrey Q. P. Crick, Michael D. Morecroft, Simon J. Duffield, Nicholas A. Macgregor, James W. Pearce-Higgins

Projected impacts of climate change on the populations and distributions of species pose a challenge for conservationists. In response, a number of adaptation strategies to enable species to persist in a changing climate have been proposed. Management to maximise the quality of habitat at existing sites may reduce the magnitude or frequency of climate-driven population declines. In addition large-scale management of landscapes could potentially improve the resilience of populations by facilitating inter-population movements. A reduction in the obstacles to species’ range expansion, may also allow species to track changing conditions better through shifts to new locations, either regionally or locally. However, despite a strong theoretical base, there is limited empirical evidence to support these management interventions. This makes it difficult for conservationists to decide on the most appropriate strategy for different circumstances. Here extensive data from long-term monitoring of woodland birds at individual sites are used to examine the two-way interactions between habitat and both weather and population count in the previous year. This tests the extent to which site-scale and landscape-scale habitat attributes may buffer populations against variation in winter weather (a key driver of woodland bird population size) and facilitate subsequent population growth.

Our results provide some support for the prediction that landscape-scale attributes (patch isolation and area of woodland habitat) may influence the ability of some woodland bird species to withstand weather-mediated population declines. These effects were most apparent among generalist woodland species. There was also evidence that several, primarily specialist, woodland species are more likely to increase following population decline where there is more woodland at both site and landscape scales. These results provide empirical support for the concept that landscape-scale conservation efforts may make the populations of some woodland bird species more resilient to climate change. However in isolation, management is unlikely to provide a universal benefit to all species.

20 Mar 20:58

In defense of P values

by (Paul A. Murtaugh)
Ecology, Volume 95, Issue 3, Page 611-617, March 2014.
Statistical hypothesis testing has been widely criticized by ecologists in recent years. I review some of the more persistent criticisms of P values and argue that most stem from misunderstandings or incorrect interpretations, rather than from intrinsic shortcomings of the P value. I show that P values are intimately linked to confidence intervals and to differences in Akaike's information criterion (ΔAIC), two metrics that have been advocated as replacements for the P value. The choice of a threshold value of ΔAIC that breaks ties among competing models is as arbitrary as the choice of the probability of a Type I error in hypothesis testing, and several other criticisms of the P value apply equally to ΔAIC. Since P values, confidence intervals, and ΔAIC are based on the same statistical information, all have their places in modern statistical practice. The choice of which to use should be stylistic, dictated by details of the application rather than by dogmatic, a priori considerations.
20 Mar 20:58

Model selection for ecologists: the worldviews of AIC and BIC

by (Ken Aho et al)
Ecology, Volume 95, Issue 3, Page 631-636, March 2014.