Shifts in bat community structure related to evolved traits and features of human-altered landscapes

Population declines for many bat species are associated with rapid, human-induced ecosystem changes. In this context, the available species pool is determined in part by historical adaptation to the native ecosystem, but the resulting community structure may be determined principally by the ability of evolved traits to function in the novel context of a human-dominated ecosystem. To investigate the role of human disturbance as a determinant of bat communities, we surveyed assemblages and species occurrence rates in 27 agriculturally dominated landscapes exhibiting a gradient of human-induced forest fragmentation in Indiana, USA. We used multiple linear regression to explore the relationship of landscape environmental variables to species diversity. We then examined the relationship between community structure, evolved species traits and fragmentation conditions across a landscape using RLQ analysis. Overall, species diversity was positively related to the amount of forest and negatively correlated with amount of urban development in a landscape. We also observed a significant relationship between evolved species traits and landscape-level variables that is consistent with globally anticipated trends for bat species extinction risk. Our findings suggest that responses of bat species to human modification of ecosystems on the scale of a few kilometers could drive distributional dynamics at larger spatial and longer temporal scales.     

Scale-specific land cover thresholds for conservation of stream invertebrate communities in agricultural landscapes

Context

In agricultural landscapes, riparian forests are used as a management tool to protect stream ecosystems from agricultural activities. However, the ability of managers to target stream protection actions is limited by incomplete knowledge of scale-specific effects of agriculture in riparian corridor and catchment areas.

Objectives

We evaluated scale-specific effects of agricultural cover in riparian corridor and catchment areas on stream benthic macroinvertebrate (BMI) communities to develop cover targets for agricultural landscapes.

Methods

Sixty-eight streams assigned to three experimental treatments (Forested Riparian, Agricultural Riparian, Agricultural Catchment) were sampled for BMIs. Ordination and segmented regression were used to assess impacts of agriculture on BMI communities and detect thresholds for BMI community metrics.

Results

BMI communities were not associated with catchment agricultural cover where the riparian corridor was forested, but were associated with variation in catchment agriculture where riparian forests had been converted to agriculture. Trait-based metrics showed threshold responses at greater than 70% agricultural cover in the catchment. Increasing agriculture in the riparian corridor was associated with less diverse and more tolerant BMI communities. Eight metrics exhibited threshold responses ranging from 45 to 75% agriculture in the riparian corridor.

Conclusions

Riparian forest effectively buffered streams from agricultural activity even where catchment agriculture exceeds 80%. We recommend managers prioritize protection of forested riparian corridors and that restore riparian corridors where agricultural cover is near identified thresholds be a secondary priority. Adoption of catchment management actions should be effective where the riparian corridor has been converted to agriculture.

     

Expanding the conservation toolbox: conservation planning of multifunctional landscapes

An area of convergence appears to be emerging between the approaches of conservation planning and the concepts of multifunctional landscapes, which if exploited correctly may assist in overcoming the resource and other constraints faced by biodiversity conservation, while at the same time furthering the aims of multifunctional landscapes to improve production abilities and overall sustainability. Using a multi-zone conservation planning approach, we explore the conservation costs, benefits to biodiversity conservation and possible ecosystem service payments associated with various land-use configurations, in the Little Karoo of South Africa, in order to develop and showcase a multifunctional landscape planning approach and its data requirements, as well as the possible cost savings to conservation agencies. The study uses four conservation planning scenarios, five land-use types, their conservation costs and biodiversity benefits, as well as possible payments from carbon sequestration and tourism. We find that the costs and biodiversity benefits associated with different land-uses varies substantially between land-uses, and also spatially within a land-use type. By incorporating this variation into a multi-zone conservation planning approach land-uses can be allocated in a way that achieves biodiversity targets while at the same time reducing costs by up to 50?% when compared with traditional binary approaches to conservation. Despite some challenges presented by cost and ecosystem service value data and the determination of land-use impacts on biodiversity and ecosystem services, the ability of conservation planning approaches to reflect differential contributions of particular land-uses to biodiversity targets and ecosystem services holds much potential for conservation planning, for multifunctional landscape objectives and for growing the resources and partnerships available to the establishment of sustainable and resilient landscapes.     

Avian soundscapes and cognitive landscapes: theory,application and ecological perspectives

The soundscape is proposed as a phenomenological entity with which to investigate environmental complexity. In particular, the avian soundtope, which is defined as a place in which sound is intentionally structured by different bird species, is regarded as an agency acting to achieve several goals. In fact, the soundtope could be viewed as a special case of an eco-field used by birds, not only to establish territorial ownership and patrol an area but also as a means of locating and evaluating the availability of many other material and immaterial resources. The meaning of the multifaceted acoustic pattern produced by bird communities during the breeding season is discussed here under the acoustic niche hypothesis in terms of community coalescence and the permanent establishment of an inter-specific communication network. Furthermore, the spatial and temporal dimensions of a bird soundscape have also been analyzed and discussed in terms of their relationship with environmental proxies. A new Acoustic Complexity Index (ACI), coupled with the implementation (ACI plug-in) of a specific sound editor (WaveSurfer©), is proposed as a way of processing sound data efficiently, thus providing new opportunities to use the bird soundscape signature for landscape characterization and describing the ecological dynamics of long-term monitoring schemes.     

Propagating sinks,ephemeral sources and percolating mosaics: conservation in landscapes

We present a framework that uses both sources and sinks as elements in the construction of a landscape matrix. We propose that the matrix be conceived as a collection of temporary habitats, some of which are sources, others of which are sinks, that form a landscape mosaic. The key element in this framing is that the sources are ephemeral and the sinks are propagating. A mean field approach is used to modify the classic metapopulation model, taking this new framework into account. Additionally a spatially explicit approach reveals different scaling rules for the percolation probability and the propagating probability.     

Dispersal success on fractal landscapes: a consequence of lacunarity thresholds

Habitat fragmentation is expected to disrupt dispersal, and thus we explored how patch metrics of landscape structure, such as percolation thresholds used to define landscape connectivity, corresponded with dispersal success on neutral landscapes. We simulated dispersal as either a purely random process (random direction and random step lengths) or as an area-limited random walk (random direction, but movement limited to an adjacent cell at each dispersal step) and quantified dispersal success for 1000 individuals on random and fractal landscape maps across a range of habitat abundance and fragmentation. Dispersal success increased with the number of cells a disperser could search (m), but poor dispersers (m<5) searching via area-limited dispersal on fractal landscapes were more successful at locating suitable habitat than random dispersers on either random or fractal landscapes. Dispersal success was enhanced on fractal landscapes relative to random ones because of the greater spatial contagion of habitat. Dispersal success decreased proportionate to habitat loss for poor dispersers (m=1) on random landscapes, but exhibited an abrupt threshold at low levels of habitat abundance (p<0.1) for area-limited dispersers (m<10) on fractal landscapes. Conventional metrics of patch structure, including percolation, did not exhibit threshold behavior in the region of the dispersal threshold. A lacunarity analysis of the gap structure of landscape patterns, however, revealed a strong threshold in the variability of gap sizes at low levels of habitat abundance (p<0.1) in fractal landscapes, the same region in which abrupt declines in dispersal success were observed. The interpatch distances or gaps across which dispersers must move in search of suitable habitat should influence dispersal success, and our results suggest that there is a critical gap-size structure to fractal landscapes that interferes with the ability of dispersers to locate suitable habitat when habitat is rare. We suggest that the gap structure of landscapes is a more important determinant of dispersal than patch structure, although both are ultimately required to predict the ecological consequences of habitat fragmentation.     

Matrix-dependent corridor effectiveness and the abundance of forest birds in fragmented landscapes

Corridor function for wildlife movement constitutes an important and desirable ecological characteristic of linear landscape structures. Changes in the matrix conditions, however, may result in substantial changes in the mechanisms responsible for the use of corridors by animals. I developed a model that describes the influence of matrix quality on the effectiveness of corridors for wildlife movement and the abundance of animals in the corridors. The model predicts that corridor effectiveness is maximized at intermediate matrix quality levels, while the abundance in the corridor increases asymptotically with matrix quality. I tested predictions of this model by comparing the expected and observed relative abundance of forest bird species in two landscape types of southern Chile. In nine out of 12 cases the model correctly predicted the relative abundance of forest birds. Riparian forest strips were expected to be effective functioning as corridors for five out of six studied species, although corridor effectiveness for each species varied between landscape types. A reasonable strategy to improve connectivity is to maintain (or to increase, if necessary) the matrix quality at a level such that corridors can function efficiently as both drift fences and movement conduits.     

Landscape cohesion: an index for the conservation potential of landscapes for biodiversity

In urbanising landscapes, planning for sustainable biodiversity occurs in a context of multifunctional land use. Important conditions for species persistence are habitat quality, the amount and configuration of habitat and the permeability of the landscape matrix. For planning purposes, these determinants should be integrated into simple indicators for spatial conditions of persistence probability. We propose a framework of three related indices. The cohesion index is based on the ecology of metapopulations in a habitat network. We discuss how an indicator for species persistence in such a network could be developed. To translate this network index into an area index, we propose the concept of spatial cohesion. Habitat cohesion and spatial cohesion are defined and measured for single species or, at best, for species profiles. Since species differ in their perception of the same landscape, different species will rate different values of these indices for the same landscape. Because landscapes are rarely planned for single species, we further propose the index of landscape cohesion, which integrates the spatial cohesion indices of different species. Indices based on these concepts can be built into GIS tools for landscape assessment. We illustrate different applications of these indices, and emphasise the distinction between ecological and political decisions in developing and applying such tools. This revised version was published online in August 2006 with corrections to the Cover Date.     

Biodiversity and ecological value of conservation lands in agricultural landscapes of southern Ontario,Canada

In eastern North America, large forest patches have been the primary target of biodiversity conservation. This conservation strategy ignores land units that combine to form the complex emergent rural landscapes typical of this region. In addition, many studies have focussed on one wildlife group at a single spatial scale. In this paper, studies of avian and anuran populations at regional and landscape scales have been integrated to assess the ecological value of agricultural mosaics in southern Ontario on the basis of the maintenance of faunal biodiversity. Field surveys of avian and anuran populations were conducted between 2001 and 2004 at the watershed and sub-watershed levels. The ecological values of land units were based on a combination of several components including species richness, species of conservation concern (rarity), abundance, and landscape parameters (patch size and connectivity). It was determined that habitats such as thicket swamps, coniferous plantations and cultural savannas can play an important role in the overall biodiversity and ecological value of the agricultural landscape. Thicket swamps at the edge of agricultural fields or roads provided excellent breeding habitat for anurans. Coniferous plantations and cultural savannas attracted many birds of conservation concern. In many cases, the land units that provided high ecological value for birds did not score well for frogs. Higher scores for avian and anuran populations were recorded along the Niagara Escarpment and other protected areas as expected. However, some private land areas scored high, some spatially connected to the protected areas and therefore providing an opportunity for private land owners to enter into a management arrangement with the local agencies.     

Consequences of delaying conservation of ecosystem services in remote landscapes prone to natural resource exploitation

Context

Natural resource extraction is expanding towards increasingly remote areas. Meanwhile, the sustainability of most ecosystem service (ES) supplies, which form a great part of the livelihoods, health and economy of inhabitants in remote regions, is threatened by large-scale land-use changes.

Objective

The aim of the study was to assess the consequences of postponing ES conservation planning in remote regions prone to industrial development. More specially, is there a development threshold at which ES conservation may be imperilled.

Methods

We simulated eight stages of development using actual data on hydroelectricity generation, forestry and mining expansion. Aiming to protect ten wetland’s ES provision, we assembled referential conservation networks prior to development and several alternative conservation solutions after each stage of development. We compared these networks and assessed the impact of land-use changes on the basic properties of ES conservation networks.

Results

We found that conservation network alternative solutions were more costly in terms of additional area needed to achieve all targets: up to 16 % more so, compared to referential networks. Past a certain stage of development, alternative solutions were composed of a significantly greater proportion of small sites and, consequently, the networks became much more fragmented. Development also changed the spatial configuration of networks: up to 66 % of the sites included in alternative solutions were not selected in the referential networks.

Conclusions

According to current trends, future development will strongly compete with ES conservation. Our study emphasizes the importance of implementing ES conservation actions before development, even in remote regions.

     

Extinction risk of wood-living model species in forest landscapes as related to forest history and conservation strategy

Dead wood is a critical resource for biodiversity in boreal forests. We analysed the persistence of five model species inhabiting dead wood. By parameterising a metapopulation model (the incidence function model), the model species were all assigned characteristics that makes it likely that they have disappeared from some (20%) forest landscapes with a long history of forest management. In the metapopulation model, a forest stand (5 ha) was regarded as a habitat patch. The amount of habitat in each patch was obtained from models of dead wood dynamics of Norway spruce in central Sweden. Dead wood generated by altered management over the entire landscape was found to be less efficient in reducing extinction risks in comparison to the same amount of dead wood generated by protecting reserves. Because generation of dead wood by altered management is often less expensive than setting aside reserves, it is difficult to determine which conservation measure is most cost-efficient. In a landscape subjected to forestry for the first time, it was better to preserve a few large reserves than many small ones. However, in a managed, highly fragmented forest landscape it was better to set aside many small reserves. The reason for this was that small plots with high habitat quality could be selected, while large reserves originally contained habitats both of high and low quality, and the rate of habitat quality increase was low. A strategy for biodiversity conservation in a managed forest landscape should include information about the history of the landscape, the current amount and spatial distribution of forest habitats, and the potential for rapid restoration of forest habitats, both on managed and unmanaged forest land.     

Designing for conservation outcomes: the value of remnant habitat for reptiles on ski runs in subalpine landscapes

Subalpine ecosystems are centres of endemism that are important for biodiversity. However, these areas are under threat from the creation, expansion and continued modification of ski runs, activities that have largely negative effects on wildlife. Despite this threat, research on the impacts of ski runs is limited for reptiles—particularly regarding the value of remnant vegetation retained on ski runs. Here we quantify the effects of habitat loss and fragmentation (i.e., patch size, patch isolation and edge effects) on the abundance of a common subalpine lizard and on thermal regimes (a key determinant of lizard distribution) in an Australian ski resort. The number of lizards observed differed significantly with habitat type (ski runs vs. forested areas) and patch isolation, but not patch size. In addition, the edges of patches supported more lizards than any other habitat type. These patterns of lizard distribution can be explained, in part, by the differing thermal regimes in each habitat. Ski runs had significantly higher ground surface temperatures than any other habitat type, precluding their use for a considerable proportion of the activity period of a lizard. In comparison, edges were characterised by lower temperatures than ski runs, but higher temperatures than the core of forested areas, potentially providing a favourable environment for thermoregulation. Based on our results, we conclude that although modified ski runs have a negative effect on lizards, patches of remnant vegetation retained on ski runs are of value for reptiles and their conservation could help mitigate the negative effects of habitat loss caused by ski run creation.     

Connectedness of habitat fragments boosts conservation benefits for butterflies,but only in landscapes with little cropland

Landscape Ecology - Global change pressures (GCPs) imperil species and associated ecosystem functions, but studies investigating interactions of landscape-scale pressures remain scarce. Loss of...     

Contrasting effects of host crops and crop diversity on the abundance and parasitism of a specialist herbivore in agricultural landscapes

Landscape Ecology - Landscape complexity affects herbivores in agroecosystems, but consequences on pest control services are variable. Carryover effects of landscape composition in previous years...     

Assessing the role of Natura 2000 at maintaining dynamic landscapes in Europe over the last two decades: implications for conservation

Context

The Natura 2000 aims to promote the persistence of biodiversity and traditional uses. European landscapes have, however, undergone large transformations in the past decades, mainly associated with the abandonment of less productive lands concentration of intensive agriculture. These changes could pose management challenges and new opportunities to the achievement of the network´s goals.

Objective

Evaluate changes in land cover within Natura 2000 in the last two decades.

Methods

We use different Corine Land Cover datasets to construct transition matrices of land uses for measuring changes for each Natura 2000 site. We also explore the role of different drivers in observed changes and assess the impacts of these changes in the structure of landscape.

Results

Landscape has been highly dynamic within Natura 2000 in the last two decades with more than 20% undergoing land cover changes. The most systematic transitions involved both, succession processes towards naturalisation in older and more abrupt protected areas (PAs) and anthropization in less steep and more recently designated PAs. Changes across land cover categories had also significant effects on the landscape configuration towards a higher homogenisation.

Conclusions

Two different strategies would be needed to enhance the role of Natura 2000, (i) tighter control to ensure anthropization, mainly intensive agriculture, does not compromise conservation goals within PAs and (ii) tackle more effectively the ecological and socio-economic effects of abandonment in less productive areas to halt loss of key habitats. On the other hand, changes in composition and structure of landscape open new conservation opportunities derived from enhanced connectivity.

     

Targeting and evaluating biodiversity conservation action within fragmented landscapes: an approach based on generic focal species and least-cost networks

The focus of biodiversity conservation is shifting to larger spatial scales in response to habitat fragmentation and the need to integrate multiple landscape objectives. Conservation strategies increasingly incorporate measures to combat fragmentation such as ecological networks. These are often based on assessment of landscape structure but such approaches fail to capitalise on the potential offered by more ecologically robust assessments of landscape function and connectivity. In this paper, we describe a modelling approach to identifying functional habitat networks and demonstrate its application to a fragmented landscape where policy initiatives seek to improve conditions for woodland biodiversity including increasing woodland cover. Functional habitat networks were defined by identifying suitable habitat and by modelling connectivity using least-cost approaches to account for matrix permeability. Generic focal species (GFS) profiles were developed, in consultation with stakeholders, to represent species with high and moderate sensitivity to fragmentation. We demonstrated how this form of analysis can be used to aid the spatial targeting of conservation actions. This ‘targeted’ action scenario was tested for effectiveness against comparable scenarios, which were based on random and clumped actions within the same landscape. We tested effectiveness using structural metrics, network-based metrics and a published functional connectivity indicator. Targeting actions within networks resulted in the highest mean woodland area and highest connectivity indicator value. Our approach provides an assessment of landscape function by recognising the importance of the landscape matrix. It provides a framework for the targeting and evaluation of alternative conservation options, offering a pragmatic, ecologically-robust solution to a current need in applied landscape ecology.     

Karst landscapes of China: patterns,ecosystem processes and services

Landscape Ecology - The karst region of southwestern China, one of the largest continuous karsts in the world, is known for its unique landscapes and rich biodiversity. This region has suffered...