LANDIS PRO predicts forest composition and structure changes incorporating species-, stand-, and landscape-scales processes at regional scales. Species-scale processes include tree growth, establishment, and mortality. Stand-scale processes contain density- and size-related resource competition that regulates self-thinning and seedling establishment. Landscape-scale processes include seed dispersal and disturbances. LANDIS PRO is designed to be compatible with forest inventory data, thus extensive inventory data can be directly utilized to initialize and calibrate model parameters before predicting future forest changes. LANDIS PRO allows for exploring the effects of disturbances, management, climate change, and modeling the spread of invasive species. We demonstrate that LANDIS PRO successfully predicts forest successional trajectories and stand development patterns in the Central Hardwood Forest region in U.S.
Shared posts
LANDIS PRO: a landscape model that predicts forest composition and structure changes at regional scales
Landscape diversity slows the spread of an invasive forest pest species
According to the associational resistance hypothesis, diverse habitats provide better resistance to biological invasions than monocultures. Host-plant abundance has been shown to affect the range expansion of invasive pests, but the effect of landscape diversity (i.e. density of host/non-host patches and diversity of forest habitat patches) on invasions remains largely untested. We used boundary displacement models and boosted regression tree analyses to investigate the effects of landscape diversity on the invasion of Corsica by the maritime pine bast scale Matsucoccus feytaudi over an 18-yr period. Taking the passive wind dispersal of the scale into account, we showed that open habitats and connectivity between host patches accelerated spread by up to 13%, whereas landscapes with high tree diversity and a high density of non-host trees decreased scale spread by up to 14%. We suggest a new mechanism for such associational resistance to pest invasion at the landscape level, which we term ‘the pitfall effect’.
The influence of interspecific interactions on species range expansion rates
Ongoing and predicted global change makes understanding and predicting species' range shifts an urgent scientific priority. Here, we provide a synthetic perspective on the so far poorly understood effects of interspecific interactions on range expansion rates. We present theoretical foundations for how interspecific interactions may modulate range expansion rates, consider examples from empirical studies of biological invasions and natural range expansions as well as process-based simulations, and discuss how interspecific interactions can be more broadly represented in process-based, spatiotemporally explicit range forecasts. Theory tells us that interspecific interactions affect expansion rates via alteration of local population growth rates and spatial displacement rates, but also via effects on other demographic parameters. The best empirical evidence for interspecific effects on expansion rates comes from studies of biological invasions. Notably, invasion studies indicate that competitive dominance and release from specialized enemies can enhance expansion rates. Studies of natural range expansions especially point to the potential for competition from resident species to reduce expansion rates. Overall, it is clear that interspecific interactions may have important consequences for range dynamics, but also that their effects have received too little attention to robustly generalize on their importance. We then discuss how interspecific interactions effects can be more widely incorporated in dynamic modeling of range expansions. Importantly, models must describe spatiotemporal variation in both local population dynamics and dispersal. Finally, we derive the following guidelines for when it is particularly important to explicitly represent interspecific interactions in dynamic range expansion forecasts: if most interacting species show correlated spatial or temporal trends in their effects on the target species, if the number of interacting species is low, and if the abundance of one or more strongly interacting species is not closely linked to the abundance of the target species.
Evaluating, partitioning, and mapping the spatial autocorrelation component in ecological niche modeling: a new approach based on environmentally equidistant records
Most species data display spatial autocorrelation that can affect ecological niche models (ENMs) accuracy-statistics, affecting its ability to infer geographic distributions. Here we evaluate whether the spatial autocorrelation underlying species data affects accuracy-statistics and map the uncertainties due to spatial autocorrelation effects on species range predictions under past and future climate models. As an example, ENMs were fitted to Qualea grandiflora (Vochysiaceae), a widely distributed plant from Brazilian Cerrado. We corrected for spatial autocorrelation in ENMs by selecting sampling sites equidistant in geographical (GEO) and environmental (ENV) spaces. Distributions were modelled using 13 ENMs evaluated by two accuracy-statistics (TSS and AUC), which were compared with uncorrected ENMs. Null models and the similarity statistics I were used to evaluate the effects of spatial autocorrelation. Moreover, we applied a hierarchical ANOVA to partition and map the uncertainties from the time (across last glacial maximum, pre-insustrial, and 2080 time periods) and methodological components (ENMs and autocorrelation corrections). The GEO and ENV models had the highest accuracy-statistics values, although only the ENV model had values higher than expected by chance alone for most of the 13 ENMs. Uncertainties from time component were higher in the core region of the Brazilian Cerrado where Q. grandiflora occurs, whereas methodological components presented higher uncertainties in the extreme northern and southern regions of South America (i.e. outside of Brazilian Cerrado). Our findings show that accounting for autocorrelation in environmental space is more efficient than doing so in geographical space. Methodological uncertainties were concentrated in outside the core region of Q. grandiflora's habitat. Conversely, uncertainty due to time component in the Brazilian Cerrado reveals that ENMs were able to capture climate change effects on Q. grandiflora distributions.
Logging and Fire in Australian Forests: errors by Attiwill et al. (2014)
Natural Versus National Boundaries: the Importance of Considering Biogeographical Patterns in Forest Conservation Policy
Abstract
Applying biogeographical insights to the regulation of production forestry and the determination of forest reserve strategies is expected to increase the effectiveness of biodiversity conservation actions. Here, we assess the extent to which such applications take place. By using Sweden as a case study, we demonstrate fundamental differences among biogeographical regions in natural patterns and processes, past land-use, and anthropogenic impacts that need to be better incorporated into strategic conservation planning and decisions. Furthermore, assessment of specific forestry regulations and biogeographical variation in a number of other countries/provinces embracing boreal and temperate biomes also indicate that natural boundaries are insufficiently considered in forest management policies. We suggest that a substantial potential exists to better align conservation priorities with biogeographical characteristics. To illustrate the application of such an approach, we present a decision support model on how forest conservation policies that rest on natural boundaries and ecological processes can be developed.
Ecosystem Services as a Contested Concept: a Synthesis of Critique and Counter-Arguments
Abstract
We describe and reflect on seven recurring critiques of the concept of ecosystem services and respective counter-arguments. First, the concept is criticized for being anthropocentric, whereas others argue that it goes beyond instrumental values. Second, some argue that the concept promotes an exploitative human–nature relationship, whereas others state that it reconnects society to ecosystems, emphasizing humanity's dependence on nature. Third, concerns exist that the concept may conflict with biodiversity conservation objectives, whereas others emphasize complementarity. Fourth, the concept is questioned because of its supposed focus on economic valuation, whereas others argue that ecosystem services science includes many values. Fifth, the concept is criticized for promoting commodification of nature, whereas others point out that most ecosystem services are not connected to market-based instruments. Sixth, vagueness of definitions and classifications are stated to be a weakness, whereas others argue that vagueness enhances transdisciplinary collaboration. Seventh, some criticize the normative nature of the concept, implying that all outcomes of ecosystem processes are desirable. The normative nature is indeed typical for the concept, but should not be problematic when acknowledged. By disentangling and contrasting different arguments we hope to contribute to a more structured debate between opponents and proponents of the ecosystem services concept.
Modelling the Holocene migrational dynamics of Fagus sylvatica L. and Picea abies (L.) H. Karst
Abstract
Aim
Vegetation dynamics and the competitive interactions involved are assumed to restrict the ability of species to migrate. But in most migration modelling approaches disturbance-driven succession and competition processes are reduced to simple assumptions or are even missing. The aim of this study was to test a combination of a migration model and a dynamic vegetation model to estimate the migration of tree species controlled by climate, environment and local species dynamics such as succession and competition.
Location
Europe.
Methods
To estimate the effect of vegetation dynamics on the migration of European beech and Norway spruce, we developed a post-process migration tool (LPJ-CATS). This tool integrates outputs of the migration model CATS and the dynamic vegetation model LPJ-GUESS. The model LPJ-CATS relies on a linear dependency between the dispersal kernel and migration rate and is based on the assumption that competition reduces fecundity.
Results
Simulating potential migration rates with the CATS model, which does not account for competition and disturbance, resulted in mean Holocene migration rates of 435 ± 55 and 330 ± 95 m year−1 for the two species Picea abies and Fagus sylvatica, respectively. With LPJ-CATS, these mean migration rates were reduced to 250 ± 75 and 170 ± 60 m year−1 for spruce and beech, respectively. Moreover, LPJ-CATS simulated migration pathways of these two species that generally comply well with those documented in the palaeo-records.
Main conclusions
Our ‘hybrid’ modelling approach allowed for the simulation of generally realistic Holocene migration rates and pathways of the two study species on a continental scale. It suggests that competition can considerably modify spread rates, but also the magnitude of its effect depends on how close climate conditions are to the niche requirements of a particular species.
Accounting for individual behavioural variation in studies of habitat selection
In Focus: DeCesare, N.J., Hebblewhite, M., Bradley, M., Hervieux, D., Neufeld, L. & Musiani, M. (2014) Linking habitat selection and predation risk to spatial variation in survival. Journal of Animal Ecology, 83, 343–352.
Resource selection is often assumed to confer enhanced fitness, but this assumption is rarely examined. In a study involving woodland caribou subject to grey wolf predation, DeCesare et al. (2014) show that while patterns of selection by caribou did correspond with a fitness proxy (survival probability), individuals did not avoid wolf predation risk to the extent that would minimize mortality. Here, we use the results of this paper as a springboard for discussing the choice of fitness proxies and the need to account for individual behavioural variation in studies of resource selection.
This In Focus article uses the study by DeCesare et al. (2014), which showed that caribou did not avoid wolf predation risk to the extent that would minimize mortality, as a springboard for discussing the choice of fitness proxies and the need to account for individual behavioural variation in analyses of resource selection.
Linking phenological shifts to species interactions through size-mediated priority effects
Summary
- Interannual variation in seasonal weather patterns causes shifts in the relative timing of phenological events of species within communities, but we currently lack a mechanistic understanding of how these phenological shifts affect species interactions. Identifying these mechanisms is critical to predicting how interannual variation affects populations and communities.
- Species' phenologies, particularly the timing of offspring arrival, play an important role in the annual cycles of community assembly. We hypothesize that shifts in relative arrival of offspring can alter interspecific interactions through a mechanism called size-mediated priority effects (SMPE), in which individuals that arrive earlier can grow to achieve a body size advantage over those that arrive later.
- In this study, we used an experimental approach to isolate and quantify the importance of SMPE for species interactions. Specifically, we simulated shifts in relative arrival of the nymphs of two dragonfly species to determine the consequences for their interactions as intraguild predators.
- We found that shifts in relative arrival altered not only predation strength but also the nature of predator–prey interactions. When arrival differences were great, SMPE allowed the early arriver to prey intensely upon the late arriver, causing exclusion of the late arriver from nearly all habitats. As arrival differences decreased, the early arriver's size advantage also decreased. When arrival differences were smallest, there was mutual predation, and the two species coexisted in similar abundances across habitats. Importantly, we also found a nonlinear scaling relationship between shifts in relative arrival and predation strength. Specifically, small shifts in relative arrival caused large changes in predation strength while subsequent changes had relatively minor effects.
- These results demonstrate that SMPE can alter not only the outcome of interactions but also the demographic rates of species and the structure of communities. Elucidating the mechanisms that link phenological shifts to species interactions is crucial for understanding the dynamics of seasonal communities as well as for predicting the effects of climate change on these communities.
Shifts in phenological timing can occur due to interannual variation in seasonal weather patterns as well as anthropogenic climate change, but the consequences for species interactions remain poorly understood. Using an experimental approach, this study demonstrates that phenological shifts can alter not only interaction strength but also demographic rates of species and community structure through a mechanism called size-mediated priority effects, in which individuals that arrive earlier can achieve a body size advantage over those that arrive later.
Indicators for taxonomic and functional aspects of biodiversity in the vineyard agroecosystem of Southern Switzerland
Source:Biological Conservation, Volume 170
Author(s): V. Trivellone , N. Schoenenberger , B. Bellosi , M. Jermini , F. de Bello , E.A.D. Mitchell , M. Moretti
It is widely accepted that the concept of biodiversity embraces two essential and complementary components: taxonomic and functional diversity. Our goal is to produce a list of plant species predictive of high taxonomic and functional biodiversity values and discuss their use within biodiversity monitoring programmes. We selected a representative sample of 48 vineyard areas from Southern Switzerland, and vegetation from the ground cover was sampled from within a total of 120 sampling plots. We considered ten widely used functional traits and selected six taxonomic and functional indices. We applied a two-step analysis: (i) using Threshold Indicator Taxa Analysis (TITAN) based on the above mentioned biodiversity indices, we defined 3 groups of sampling plots with low (L), medium (M) and high (H) biodiversity values; (ii) using the Indicator Value analysis, we identify indicator species that are significantly associated with the above-mentioned groups and their combinations. In total, 259 vascular plants were identified across the sampling plots. As a whole, 52 species were significant indicators for groups with high and mid-to-high biodiversity values. Out of all indicator species, 24 (46%) were exclusively selected by functional biodiversity indices whereas only 10 (19%) were associated with taxonomic indices. Eighteen (35% of the total) species were selected by both types of indices. We point out that indicator species associated with two different aspects of biodiversity show a high degree of complementarity. Our results emphasize the need to consider functional aspects of biodiversity in diversity-conservation strategies when the objectives are to preserve both taxonomic diversity and ecosystem functioning.
Integrating connectivity and climate change into marine conservation planning
Source:Biological Conservation, Volume 170
Author(s): Rafael A. Magris , Robert L. Pressey , Rebecca Weeks , Natalie C. Ban
Most applications of systematic conservation planning have not effectively incorporated biological processes or dynamic threats. We investigated the extent to which connectivity and climate change have been considered in an ecologically meaningful way in marine conservation planning, as an attempt to help formulate conservation objectives for population persistence, over and above representation. Our review of the literature identified 115 marine planning studies that addressed connectivity and 47 that addressed the effects of climate change. Of the statements identified that related to goals and objectives, few were quantitative and justified by ecological evidence for either connectivity (13%) or climate change (8.9%). Most studies addressing connectivity focused on spatial design (e.g. size and spacing) of marine protected areas (MPAs) or clustering of planning units. Climate change recommendations were primarily based on features related to MPA placement (e.g. preferences for areas relatively resilient and resistant to climate change impacts). Quantitative methods to identify spatial or temporal dynamics of features related to connectivity and/or climate change (e.g. functionally well-connected or thermal refugia areas) were rare, and these accounted for the majority of ecologically justified statements. Given these shortcomings in the literature, we outline a framework for setting marine conservation planning objectives that describes six key approaches to more effectively integrate connectivity and climate change into conservation plans, aligning opportunities and minimizing trade-offs between both issues.
Conservation of herpetofauna in northern landscapes: Threats and challenges from a Canadian perspective
Source:Biological Conservation, Volume 170
Author(s): David Lesbarrères , Sara L. Ashpole , Christine A. Bishop , Gabriel Blouin-Demers , Ronald J. Brooks , Pierre Echaubard , Purnima Govindarajulu , David M. Green , Stephen J. Hecnar , Tom Herman , Jeff Houlahan , Jacqueline D. Litzgus , Marc J. Mazerolle , Cynthia A. Paszkowski , Pamela Rutherford , Danna M. Schock , Kenneth B. Storey , Stephen C. Lougheed
The scientific community is increasingly aware that many amphibian and reptile species have experienced dramatic decreases in abundance and distribution, with at least 43% of amphibian species exhibiting population declines and 19% of all reptile species threatened with extinction since 2000. Species suffer from a suite of threats including habitat destruction, alteration and fragmentation, introduced species, over-exploitation, climate change, UV-B radiation, chemical contaminants, diseases and the synergisms among them. These worldwide threats are also present in northern landscapes and in Canada in particular where 20 amphibian and 37 reptile species are listed as at-risk by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC). In fact, with more than 80° in longitude and 40° in latitude, Canada presents both a diversity of northern ecosystems and a range of threats to its herpetofauna at least equal to other countries. The physical scale of Canada, its varied climate, its economic realities, and the legislative differences among levels of government and their respective mandates have long challenged traditional approaches to conservation. However, science and stewardship are leading forces in the conservation of emblematic species at risk in Canada and can serve to inform best practices elsewhere. Recent advances in data analysis and management have transformed our understanding of populations in northern landscapes. Canadian amphibians and reptiles, most of which are cold-adapted species at the northern edge of their distribution, can serve as case studies to improve modeling of population dynamics, create cogent, science-based policies, and prevent further declines of these taxa.
Enhancing urban biodiversity and its influence on city-dwellers: An experiment
Source:Biological Conservation, Volume 171
Author(s): Assaf Shwartz , Anne Turbé , Laurent Simon , Romain Julliard
Urbanization is presenting a growing problem for biodiversity conservation, notably by increasingly isolating over half of the world’s population from the experience of nature. This separation of people from nature is an important environmental issue, as it could fundamentally influence the way people value nature and their willingness to conserve it. Here we provide the first experimental study that jointly explores how urban biodiversity can be enhanced and how these changes may influence some aspects of people–biodiversity interactions.We significantly increased the diversity of flowers, birds and pollinators in small public gardens (Paris, France) by providing additional resources (i.e., planting flower-meadows and placing nesting-boxes). Semi-structured interviews were conducted in situ with 1116 regular garden users before and after the manipulation. Close-ended questionnaires were completed exploring the respondents’ biodiversity perception and their sensitivity to the changes in biodiversity. Our results highlight a people–biodiversity paradox between people’s perceptions and biodiversity awareness. Respondents expressed a strong preference for a rich diversity of species (excluding insects) and related this diversity to their well-being in the gardens. However, they did not notice the diversity of species. Respondents underestimated species richness and only noticed the changes in native flower richness in those gardens where advertisement and public involvement were organized. More experimental interdisciplinary studies are needed to further explore the people–biodiversity interactions. This would help expose the role that urban biodiversity plays in people’s daily life and the importance of this interaction for raising public support for general conservation policies.
Decreased fitness of restocked hybrid quails prevents fast admixture with wild European quails
Source:Biological Conservation, Volume 171
Author(s): Manel Puigcerver , Ines Sanchez-Donoso , Carles Vilà , Francesc Sardà-Palomera , Eduardo García-Galea , José Domingo Rodríguez-Teijeiro
Restocking with non-native species for hunting purposes is a widespread practice in some Galliformes species that may result in the introgression of maladaptive alleles into native populations. Quails farmed for restocking are produced by interbreeding domestic Japanese quails (Coturnix japonica) with European quails (Coturnix coturnix). Massive releases of these animals could represent a threat to native European quails. In this study we radio-track 16 female native European quails and 51 female farm-reared quails over four breeding seasons in a single locality. Our results show that farmed female quails attracted more wild common quail males than European quail females, probably because they produce more rally calls. Here for the first time we show empirical evidence that European quails and restocked farmed quails interbreed in the wild. Further, hybrid farmed females and European females had similar probabilities of mating, nesting success, clutch size, fertility, hatching probability and chicks’ survival probability. However, female farmed quail had higher mortality than European quail females, and their nests had a higher rate of predation. These last observations could explain why the two lineages do not appear completely admixed after more than 20years of massive restocking practices. However, our results clearly show a lack of reproductive barriers in the wild and that introgression may not be completely prevented. An immediate ban of the release of non-native quails is necessary to preserve their genetic integrity. Thus, banning restocking with Japanese quail or hybrids is necessary to prevent the progressive introduction of maladaptive alleles into the European quail populations.
Propagating Uncertainty in Plot-based Estimates of Forest Carbon Stock and Carbon Stock Change
Abstract
Ecosystem science increasingly relies on highly derived metrics to synthesize across large datasets. However, full uncertainty associated with these metrics is seldom quantified. Our objective was to evaluate measurement error and model uncertainty in plot-based estimates of carbon stock and carbon change. We quantified the measurement error associated with live stems, deadwood and plot-level variables in temperate rainforest in New Zealand. We also quantified model uncertainty for height–diameter allometry, stem volume equations and wood-density estimates. We used Monte Carlo simulation to assess the net effects on carbon stock and carbon change estimated using data from 227 plots from throughout New Zealand. Plot-to-plot variation was the greatest source of uncertainty, amounting to 9.1% of mean aboveground carbon stock estimates (201.11 MgC ha−1). Propagation of the measurement error and model uncertainty resulted in a 1% increase in uncertainty (0.1% of mean stock estimate). Carbon change estimates (mean −0.86 MgC ha−1 y−1) were more uncertain, with sampling error equating to 56% of the mean, and when measurement error and model uncertainty were included this uncertainty increased by 35% (22.1% of the mean change estimate). For carbon change, the largest sources of measurement error were missed/double counted stems and fallen coarse woody debris. Overall, our findings show that national-scale plot-based estimates of carbon stock and carbon change in New Zealand are robust to measurement error and model uncertainty. We recommend that calculations of carbon stock and carbon change incorporate both these sources of uncertainty so that management implications and policy decisions can be assessed with the appropriate level of confidence.
Voting Systems for Environmental Decisions
Abstract
Voting systems aggregate preferences efficiently and are often used for deciding conservation priorities. Desirable characteristics of voting systems include transitivity, completeness, and Pareto optimality, among others. Voting systems that are common and potentially useful for environmental decision making include simple majority, approval, and preferential voting. Unfortunately, no voting system can guarantee an outcome, while also satisfying a range of very reasonable performance criteria. Furthermore, voting methods may be manipulated by decision makers and strategic voters if they have knowledge of the voting patterns and alliances of others in the voting populations. The difficult properties of voting systems arise in routine decision making when there are multiple criteria and management alternatives. Because each method has flaws, we do not endorse one method. Instead, we urge organizers to be transparent about the properties of proposed voting systems and to offer participants the opportunity to approve the voting system as part of the ground rules for operation of a group.
Sistemas de Votación para Decisiones Ambientales
Resumen
Los sistemas de votación agregan preferencias eficientemente y muy seguido se usan para decidir prioridades de conservación. Las características deseables de un sistema de votación incluyen la transitividad, lo completo que sean y la optimalidad de Pareto, entre otras. Los sistemas de votación que son comunes y potencialmente útiles para la toma de decisiones ambientales incluyen simple mayoría, aprobación y votación preferencial. Desafortunadamente, ningún sistema de votación puede garantizar un resultado y a la vez satisfacer un rango de criterios de desempeño muy razonable. Además, los métodos de votación pueden manipularse por los que toman las decisiones y votantes estratégicos si tienen el conocimiento de los patrones de votación y de las alianzas entre miembros dentro de las poblaciones votantes. Las propiedades difíciles de los sistemas de votación sobresalen en las tomas de decisiones rutinarias cuando hay criterios múltiples y alternativas de manejo. Ya que ambos métodos tienen fallas, no apoyamos a uno sobre el otro. En lugar de esto le pedimos urgentemente a los organizadores ser transparentes con respecto a las propiedades de los sistemas de votación y ofrecer a los participantes la oportunidad de aprobar el sistema de votación como parte de las reglas básicas para la operación de un grupo.
Designing cost-efficient surveillance for early detection and control of multiple biological invaders
Wood borers and bark beetles are among the most serious forest pests worldwide. Many such species have become successful invaders, often causing substantial, costly damages to forests. Here we design and evaluate the cost-efficiency of a trap-based surveillance program for early detection of wood borers and bark beetles at risk of establishing in New Zealand. Though costly, a surveillance program could lead to earlier detection of newly established forest pests, thereby increasing the likelihood of successful eradication and reducing control costs and damages from future invasions. We develop a mechanistic bioeconomic model that relates surveillance intensity (i.e., trap density) and invasion size to probabilities of detection and control; it captures the dynamics of invasive species establishment, spread, and damages to urban and plantation forests. We employ the model to design surveillance programs that provide the greatest net present benefits. Our findings suggest that implementing a surveillance trapping program for invasive wood borers and bark beetles would provide positive net benefits under all scenarios considered. The economically optimal trapping strategy calls for a very high investment in surveillance: about 10,000 traps in each year of the 30-year surveillance program, at a present value cost of US$54 million. This strategy provides a 39% reduction in costs compared with no surveillance, corresponding to an expected net present benefit of approximately US$300 million. Although surveillance may provide the greatest net benefits when implemented at relatively high levels, our findings also show that even low levels of surveillance are worthwhile: the economic benefits from surveillance more than offset the rising costs associated with increasing trapping density. Our results also show that the cost-efficiency of surveillance varies across target regions because of differences in pest introduction and damage accumulation rates across locales, with greater surveillance warranted in areas closer to at-risk high-value resources and in areas that receive more imported goods that serve as an invasion pathway.
Conviviendo con el fuego [Documental]
The next best thing: how well do secondary forests preserve biodiversity?
Exotic birds show lags in population growth
Abstract
Aim
A key aspect of the ecology and management of biological invasions is the prevalence and duration of lag phases in population growth. Here, we explore the occurrence of lag phases in exotic bird populations using the Audubon Christmas Bird Count database.
Location
Hawaiian Island archipelago.
Methods
We expand on the use of piecewise model fitting techniques to detect lags in exotic bird populations on Hawaii. We searched for explanations as to the occurrence of these lags using five possible mechanisms (body size, niche breadth, propagule pressure, length of record and lag phase growth rate).
Results
We found evidence of lag phases for 14 of 17 species we evaluated (range: 10–38 years, mean using observed data = 16 ± 12), and we discovered very rapid growth to maximum abundance following the end of the lag phase (mean using observed data = 8 ± 6 years). We found no evidence for any association between the possible mechanisms influencing the occurrence and duration of the lag phases.
Main conclusions
Our results are the first to rigorously quantify lags in exotic animal populations; most existing evidence comes from plants. We show that lags are as common in birds as in plants, although we provide preliminary evidence that the duration of lags in birds is shorter than in plants. We highlight the need for continued efforts to elucidate lag phase occurrence and duration in biological invasions, and we demonstrate the expanded utility of piecewise model fitting approaches to quantify these lags using count data.
Agriculture and nature: Trouble and strife?
Source:Biological Conservation, Volume 170
Author(s): Frédéric Baudron , Ken E. Giller
Global demand for agricultural products is expected to double in the next decades, putting tremendous pressure on agriculture to produce more. The bulk of this increase will come from developing countries, which host most biodiversity-rich areas of the planet. Whilst most biodiversity is found in production landscapes shared with people, where agriculture represents an increasing threat, international conservation organisations continue to focus on the maintenance and expansion of the network of protected areas. When conservation organisations partner with agricultural programmes, they promote low input, extensive agriculture. Combined with the focus on protected areas, this may exacerbate rather than mitigate conflicts between biodiversity conservation and agricultural production. Two models have been proposed to increase agricultural production whilst minimising the negative consequences for biodiversity: ‘land sparing’ and ‘land sharing’. Although often polarized in debates, both are realistic solutions, depending on the local circumstances. We propose a number of criteria that could guide the choice towards one or the other. We conclude that general principles to be considered in both land sparing and land sharing are: managing spillover effects, maintaining resilience and ecosystem services, accounting for landscape structure, reducing losses and wastes, improving access to agricultural products in developing countries and changing consumption patterns in developed countries, and developing supportive markets and policies.
Factors determining the abundance and occurrence of Hermann’s tortoise Testudo hermanni in France and Spain: Fire regime and landscape changes as the main drivers
Source:Biological Conservation, Volume 170
Author(s): Thibaut Couturier , Aurélien Besnard , Albert Bertolero , Valérie Bosc , Guillelme Astruc , Marc Cheylan
Major landscape transformations have occurred in the northern Mediterranean over the last decades, including urbanization, agricultural intensification and land abandonment, which, in turn, increase the risk of the propagation of fire. We used repeated-count surveys conducted at 369 sites in France and Spain to jointly model the effects of environmental covariates on the abundance, occupancy and detection of Hermann’s tortoise, a long-lived and endangered species, using a novel zero-inflated approach. We also employed a large dataset of presence-only data collected in Provence to model environmental influences on occurrence probability using maximum entropy models. In both France and Spain, sites that experienced wildfires over the last 50years hosted 31% fewer individuals than unburned sites. In Provence, higher wildfire frequency decreased this species’ occurrence probability, from 50% when 0–1 fire had occurred over the last 50years, to 7% in areas that had burned at least 3 times. We also showed that abundance required a long recovery time (more than 25years) after wildfires. In Provence, the highest occurrence probability for this species was found in patchy landscapes and scrub and/or herbaceous vegetation. The lowest species occurrence was found in extensive artificial areas, vineyards and arable lands. These results suggest a high risk of population extinction in the future if these types of habitats continue to expand in plains and coastal areas to the detriment of scrublands. Higher wildfire frequency predicted by climate change scenarios in the Mediterranean is also likely to increase the risk of extinction for some populations.
Structured analysis of conservation strategies applied to temporary conservation
Source:Biological Conservation, Volume 170
Author(s): Atte Moilanen , Jussi Laitila , Timo Vaahtoranta , Lynn V. Dicks , William J. Sutherland
We present a novel framework for the structured analysis of conservation strategies, concentrating on their conceptual, causal, logical and qualitative aspects. The analysis both increases our understanding of conservation strategies and provides a tool for supporting their use in decision making. It facilitates answering such questions as: What are the basic characteristics of the strategy? What are its biological targets? What are its aims, paths of influence and expected benefits? Where should the strategy best be applied and by whom? How should the strategy be applied over time? What are the data needs? What major assumptions underlie the strategy? Which are the major costs, constraints, and uncertainties that might influence its feasibility and application? How does the strategy relate to other conservation strategies? Are there viable alternatives? We also examine the emergent properties of the strategy, asking what the world would be like if the strategy was applied extensively. We examine the usefulness of structured analysis by applying it to the strategy of temporary conservation, which incorporates dynamic reserves and temporary conservation contracts, either to maintain a regional distribution of successional habitats or to facilitate climate-change induced range shifts of species. This application showed that these strategies have appeared under various names, that they require extensive data, that implementation involves significant uncertainties, and that associated uncertainties increase through time. Applying the proposed framework to a range of conservation strategies would improve our ability to identify most appropriate paths of conservation when many alternatives exist.
Toward better application of minimum area requirements in conservation planning
Source:Biological Conservation, Volume 170
Author(s): Guy Pe’er , Mariana A. Tsianou , Kamila W. Franz , Yiannis G. Matsinos , Antonios D. Mazaris , David Storch , Lenka Kopsova , Jana Verboom , Michel Baguette , Virginie M. Stevens , Klaus Henle
The Minimum Area Requirements (MAR) of species is a concept that explicitly addresses area and therefore can be highly relevant for conservation planning and policy. This study compiled a comprehensive database of MAR estimates from the literature, covering 216 terrestrial animal species from 80 studies. We obtained estimates from (a) Population Viability Analyses (PVAs) which explored a range of area-related scenarios, (b) PVAs that provided a fixed value – either MAR or the minimum viable population size (MVP) alongside other area-relevant information, and (c) empirical studies of occupancy patterns in islands or isolated habitat patches across area. We assessed the explanatory power of life-history traits (body mass, feeding guild, generation length and offspring size), environmental variables (average precipitation and temperature), research approach and phylogenetic group on MAR estimates. PVAs exploring area showed strong correlation between MAR and body mass. One to two additional variables further improved the predictive power. PVA reporting fixed MAR, and occupancy-based studies, were better explained by the combination of feeding guild, climatic variables and additional life history traits. Phylogeny had a consistent but usually small contribution to the predictive power of models. Our work demonstrates that estimating the MAR across species and taxa is achievable but requires cautious interpretation. We further suggest that occupancy patterns are likely sensitive to transient dynamics and are therefore risky to use for estimating MAR. PVA-based evaluations enable considering time horizon and extinction probability, two aspects that are critical for future implementation of the MAR concept into policy and management.
Identifying key habitats to conserve the threatened brown bear in the Himalaya
Source:Biological Conservation, Volume 170
Author(s): Muhammad Ali Nawaz , Jodie Martin , Jon E. Swenson
The threatened Himalayan brown bear has a fragmented range in the Himalayas. However, its habitat has never been documented, which hinders conservation efforts. The Deosai Plateau in northern Pakistan has long been recognized as the core area for this subspecies in the country. To provide knowledge to help conserve the remnant populations in the Himalayan region, and especially in protected areas, we investigated habitat selection of brown bears and the influence of human presence on brown bear distribution in Deosai National Park, Pakistan.We used an Ecological Niche Factor Analysis to assess brown bear habitat selection, using scats sampled along transect routes throughout the park as location data. Habitat use based on 137 observations of brown bears during monitoring confirmed that differential scat detectability did not bias our results. Only 65% of the park area had productive vegetation. Our analyses indicated that brown bears avoided higher elevations and steeper slopes and selected more productive parts of the park (marshy, grassy, and stony vegetation types). The marshy vegetation was the most preferred habitat, probably because it had the highest forage production and density of golden marmots. Brown bears tolerated human infrastructures, like roads and camps, but strongly avoided grazing areas with high livestock density. The habitat suitability map generally followed the biomass productivity patterns of the park. It indicated the central part as suitable, and classified half of the park, mainly peripheral areas, as unsuitable for brown bears.The vegetation and habitat suitability maps also provide an objective criterion for evaluating present and future developments in the park. Until recently, communities seem to have used the park’s resources without significantly affecting the brown bear population. However, in recent years a large influx of nomadic communities with their livestock has become a challenge, which needs urgent attention to continue the present brown bear population recovery and to secure its habitat. We recommend monitoring the livestock and conducting a detailed inventory of the rangeland to understand grazing dynamics in the park and to maintain sustainable stocking rates.
Capacity of older plantations to host bird assemblages of naturally-regenerated conifer forests: A test at stand and landscape levels
Source:Biological Conservation, Volume 170
Author(s): Allison MacKay , Maxime Allard , Marc-André Villard
Conifer plantations are thought to provide lower-quality habitat for many old forest specialists because of their simplified stand structure and relative paucity of habitat elements such as dead wood. However, at the landscape scale, plantations may have a positive influence on biodiversity, e.g. through landscape supplementation. Here, we test the quality of older spruce plantations as breeding habitat for forest birds at local and landscape levels. We compared bird species assemblages of 40–50year-old native spruce plantations with those of mature, naturally-regenerated conifer forests using a Bayesian hierarchical model, which accounts for imperfect detection of species. Median species richness was higher in naturally-regenerated conifer stands than in spruce plantations (29.2 vs. 24.4; 95% probability interval=3.9–5.7), which probably reflects the absence of primary cavity nesters from many stations within plantations. In contrast, more species of canopy nesters were detected in plantations. The proportion of naturally-regenerated conifer forest in the landscape was a predictor of species occurrence for five ground nesters, four primary cavity nesters, and two weak excavators. Older spruce plantations did not provide suitable habitat for some species, mainly cavity nesters. Snag densities in plantations were lower than the estimated threshold requirements for several cavity-nesting birds. Hence, mature, naturally-regenerated forest patches are essential components of intensively-managed forest landscapes to maintain rich forest bird assemblages.
A spatially explicit approach to assess the collision risk between birds and overhead power lines: A case study with the little bustard
Source:Biological Conservation, Volume 170
Author(s): João Paulo Silva , Jorge Manuel Palmeirim , Rita Alcazar , Ricardo Correia , Ana Delgado , Francisco Moreira
Collisions between birds and overhead power lines are an important cause of human-induced mortality. Mapping collision risk is an important prerequisite to minimise the negative impact of these structures on bird populations, particularly for species of high conservation concern and that are prone to collision. We mapped and modelled power line collision risk of a threatened and collision-prone species, the little bustard (Tetrax tetrax), based on three types of information: (i) the average daily distance flown by an individual, calculated from a satellite-telemetry study; (ii) the average percentage of flight movements at phase-conductor or shield-wire height, based on field focal observations; and (iii) a habitat suitability map for three different seasons (breeding, post-breeding and winter), modelled from an independent dataset of a nationwide population survey. An overall spatially explicit collision risk map was generated and validated with an independent mortality dataset derived from monitoring bird casualties in a sample of power lines. Collision risk of little bustards varied significantly both spatially and temporally. Compared to post-breeding and winter, little bustards moved smaller distances and flew at lower risk height during the breeding season, therefore minimising collision risk. The overall collision risk map contributed with relevant information to predict the likelihood of mortality events in a set of sampled power line sections. The described approach can be extended to transmission power lines, as well as to other bird species.
Living and dying in a multi-predator landscape of fear: roe deer are squeezed by contrasting pattern of predation risk imposed by lynx and humans
The theory of predation risk effects predicts behavioral responses in prey when risk of predation is not homogenous in space and time. Prey species are often faced with a tradeoff between food and safety in situations where food availability and predation risk peak in the same habitat type. Determining the optimal strategy becomes more complex if predators with different hunting mode create contrasting landscapes of risk, but this has rarely been documented in vertebrates. Roe deer in southeastern Norway face predation risk from lynx, as well as hunting by humans. These two predators differ greatly in their hunting methods. The predation risk from lynx, an efficient stalk-and-ambush predator is expected to be higher in areas with dense understory vegetation, while predation risk from human hunters is expected to be higher where visual sight lines are longer. Based on field observations and airborne LiDAR data from 71 lynx predation sites, 53 human hunting sites, 132 locations from 15 GPS-marked roe deer, and 36 roe deer pellet locations from a regional survey, we investigated how predation risk was related to terrain attributes and vegetation classes/structure. As predicted, we found that increasing cover resulted in a contrasting lower predation risk from humans and higher predation risk from lynx. Greater terrain ruggedness increased the predation risk from both predators. Hence, multiple predators may create areas of contrasting risk as well as double risk in the same landscape. Our study highlights the complexity of predator–prey relationship in a multiple predator setting.
Synthesis
In this study of risk effects in a multi-predator context, LiDAR data were used to quantify cover in the habitat and relate it to vulnerability to predation in a boreal forest. We found that lynx and human hunters superimpose generally contrasting landscapes of fear on a common prey species, but also identified double-risk zones. Since the benefit of anti-predator responses depends on the combined risk from all predators, it is necessary to consider complete predator assemblages to understand the potential for and occurrence of risk effects across study systems.
Occupancy Patterns of Regionally Declining Grassland Sparrow Populations in a Forested Pennsylvania Landscape
Abstract
Organisms can be affected by processes in the surrounding landscape outside the boundary of habitat areas and by local vegetation characteristics. There is substantial interest in understanding how these processes affect populations of grassland birds, which have experienced substantial population declines. Much of our knowledge regarding patterns of occupancy and density stem from prairie systems, whereas relatively little is known regarding how occurrence and abundance of grassland birds vary in reclaimed surface mine grasslands. Using distance sampling and single-season occupancy models, we investigated how the occupancy probability of Grasshopper (Ammodramus savannarum) and Henslow's Sparrows (A. henslowii) on 61 surface mine grasslands (1591 ha) in Pennsylvania changed from 2002 through 2011 in response to landscape, grassland, and local vegetation characteristics . A subset (n = 23; 784 ha) of those grasslands were surveyed in 2002, and we estimated changes in sparrow density and vegetation across 10 years. Grasshopper and Henslow's Sparrow populations declined 72% and 49%, respectively from 2002 to 2011, whereas overall woody vegetation density increased 2.6 fold. Henslow's Sparrows avoided grasslands with perimeter–area ratios ≥0.141 km/ha and woody shrub densities ≥0.04 shrubs/m2. Both species occupied grasslands ≤13 ha, but occupancy probability declined with increasing grassland perimeter–area ratio and woody shrub density. Grassland size, proximity to nearest neighboring grassland (
= 0.2 km), and surrounding landscape composition at 0.5, 1.5, and 3.0 km were not parsimonious predictors of occupancy probability for either species. Our results suggest that reclaimed surface mine grasslands, without management intervention, are ephemeral habitats for Grasshopper and Henslow's Sparrows. Given the forecasted decline in surface coal production for Pennsylvania, it is likely that both species will continue to decline in our study region for the foreseeable future.
Patrones de Ocupación de Poblaciones Regionalmente Declinantes de Gorriones de Pastizales en un Paisaje Boscoso de Pennsylvania
Resumen
Los organismos pueden ser afectados por procesos en el paisaje que los rodea por fuera de los límites de las áreas de hábitat y por las características de la vegetación local. Hay un interés sustancial en entender cómo estos procesos afectan a las poblaciones de aves de pastizales, las cuales han experimentado declinaciones sustanciales en la población. Mucho de nuestro conocimiento con respecto a los patrones de ocupación y a la densidad parten de sistemas de praderas, mientras que relativamente se sabe poco con respecto a cómo la ocurrencia y la abundancia de las aves de pastizales varía en pastizales de minas de superficiales reclamadas. Usando muestreo a distancia y modelos de ocupación de una sola temporada, investigamos cómo la probabilidad de ocupación de los gorriones Ammodramus savannarum y A. henslowii en 61 pastizales de minas superficiales (1591 ha) en Pennsylvania, que han cambiado desde 2002 y hasta el 2011 n respuesta a las características de paisaje, pastizales y de la vegetación local. Un subconjuto (n = 23; 784 ha) de estos pastizales fue muestreado en 2002 y estimamos cambios en la densidad de gorriones y en la vegetación a lo largo de 10 años. Las poblaciones de A. savannarum y A, henslowii declinaron 72% y 49% respectivamente de 2002 a 2011, mientras que la densidad de la vegetación leñosa en general incrementó al 2.6. Los gorriones A. henslowii evitaron los pastizales con radios de área-perímetro ≥0.141 km/ha y con densidades de arbustos leñosos ≥0.04 arbustos/m2. Ambas especies ocuparon pastizales ≤ 13 ha, pero la probabilidad de ocupación declinó con el incremento en el radio área-perímetro de los pastizales y la densidad de arbustos leñosos. El tamaño del pastizal, la proximidad al pastizal vecino más cercano (= 0.2 km) y la composición de los paisajes circundantes en 0.5 km, 1.5 km y 3.0 km no fueron indicadores parsimoniosos de la probabilidad de ocupación para ambas especies. Nuestros resultados sugieren que los pastizales de minas superficiales reclamadas, sin intervención del manejo, son hábitats efímeros para gorriones A. savannarum y A. henslowii. Dada la declinación predicha en la producción de carbón superficial para Penssylvania, es probable que ambas especies continúen declinando en nuestra región de estudio en el futuro.