Habitat fragmentation and parasitism of a forest damselfly

We compared populations of a forest damselfly —Calopteryx maculata — in two kinds of landscapes. In fragmented landscapes, forested foraging patches were separated from streams (where oviposition and mating occur) by up to 500 m of pasture. In non-fragmented landscapes, there was continuous forest cover adjacent to streams. The prevalence and intensity of midgut infections of a gregarine parasite were significantly lower in the fragmented landscapes than in the non-fragmented landscapes. We have shown elsewhere that in the fragmented landscapes, damselflies move over greater areas to forage than in the non-fragmented landscapes. We postulate that these movements lower the rate of encounter between damselflies and oocysts, thus lowering the prevalence and intensity of infection. The differences suggest that actual habitat fragmentation events would alter the relationship between host and parasite, but that populations of both species would persist after fragmentation. Prevalence of parasitism is related to age but we found no residual effects of size on parasitism.     

Habitat factors related to wild rabbit conservation in an agricultural landscape

Populations of European wild rabbit (Oryctolagus cuniculus) have been decreasing since the 1950s. Changes in agricultural practices have been suggested as reasons for their decline in Mediterranean landscapes. We evaluated the environmental variables affecting rabbit distribution in a semiarid agricultural landscape of Northeastern Spain. Sampling was performed in 147 sites randomly distributed across Zaragoza province. At each site, data were recorded in five 100 m segments along a 1 km transect, following ecotones between crops and natural-vegetation areas. A rabbit abundance index was estimated from latrine count, pellet density and number of plots with pellets. In addition to environmental variables that have been shown to be related to rabbit abundance in other habitats, as climate, soil hardness and topography of the site, we measured landscape components related to agricultural use, such as structure of natural vegetation in remaining areas non-devoted to agricultural use and distances to different types of crops and to ecotone between crop and natural vegetation. Our results showed that rabbit abundance was positively correlated to yearly mean temperature, February and May mean rainfall, and negatively correlated to September and November mean rainfall, hardness of soil, and site topography. In relation to agricultural use, rabbit abundance was positively correlated to the scrub structure of natural-vegetation areas and negatively correlated to distance to edge between cultivated unirrigated cereal crops (wheat or barley) and yearly resting cereal crops. Rabbit abundance increased only when the edge between alternate cereal crops was less than 50 m from the ecotone between crops and natural vegetation.This revised version was published online in May 2005 with corrections to the Cover Date.     

Small urban woodlands as biodiversity conservation hot-spot: a multi-taxon approach

To evaluate the importance of urban woodlands to serve as potential sites for biodiversity conservation, we analysed bird, carabid beetle and small mammal community responses to urbanisation at different spatial scales. We analysed the relationships between the variations of the structure (species richness S, diversity H′ and dominance D) of animal communities of woodlands distributed along a rural–urban gradient, and the variations along this same gradient of (1) the vegetation within woodlands, (2) the landscape at 100 m and (3) 600 m around the woodlands. We identified the spatial scales whose variations along the gradient most affected each animal community structure, and characterised community responses to these variations. Our results showed that urbanisation affected taxa differently according to their dispersal ability. Carabid beetles, less mobile, seem to be sensitive to increasing fragmentation and built surfaces from periurban to town centre which could make their movement within the urban landscape difficult. Birds, mobile species, seem to be more sensitive to variations of the vegetation structure within woodlands from periurban to town centre that could affect their capacity to maintain in habitat patches. Although our study did not allow relating the small mammal community structure to urbanisation, it suggests that this taxa is sensitive to urban local disturbances. A relevant management scale of woodlands can be specified for each taxa conservation. Urban woodlands accommodate over 50% of the species present in periurban woodlands, and effective management could enhance this number. Woodlands seem to be a good choice for promoting biodiversity conservation in towns.     

Setting conservation priorities in cities: approaches,targets and planning units adapted to wetland biodiversity and ecosystem services

Context

Protecting wetlands in cities is challenging. A cost-effective spatial prioritization approach taking into account stakeholder motivations is needed to identify wetlands of conservation interest.

Objectives

This study aims to optimize the efficiency of a systematic conservation planning (SCP) approach to protect nine urban wetland ecosystem services (ES) and biodiversity.

Methods

First, we mapped ES supply and demand to capture their spatial variation as they occur at the wetland scale. Secondly, using wetland property value as cost data, we compared the efficiency of SCP to two multicriteria scoring approaches. Thirdly, we compared SCP alternatives by changing the planning unit scale and conservation objectives (i.e. emphasizing ES demand and focusing on the most important ES).

Results

The total cost of the scoring approach networks was minimally 13 times higher, when compared to the SCP approaches. Consequently, the scoring approaches were at least five times less efficient than SCP per unit of network area ($/m²). Decreasing the size of planning units resulted in further cost reduction, with networks that were up to 92% less costly. We also highlighted that beneficiary demand fulfillment in networks could be optimized without a loss in efficiency. Finally, SCP secured nine ES for the same expenditure as that required to protect four public safety related ES. However, planning solely for these four important ES failed to represent those of other ES.

Conclusions

Our results may provide a tool to better inform land use decision planning in order to mitigate the impacts of urban growth on ES.

     

The risk of ignoring fear: underestimating the effects of habitat loss and fragmentation on biodiversity

Landscape Ecology - Habitat loss and fragmentation threaten species not only through structural landscape changes and resource reduction, but also through modifications to species’...     

Habitat alteration and habitat fragmentation differentially affect beta diversity of stream fish communities

Context

The cumulative impact of broad scale environmental change includes altered land-cover and fragmentation. Both altered land-cover and fragmentation have a negative effect on species diversity, but the scale they act on may differ because land-cover alters environmental characteristics, whereas fragmentation alters movement among sites.

Objectives

We evaluated the scale specific effects of land-cover, fragmentation, and habitat size on alpha and beta diversity (total, turnover, and nestedness).

Methods

Stream fish communities were sampled across five urbanizing watersheds. Generalized mixed linear models were used to test how diversity (alpha and beta) is affected by land-cover, connectivity, and habitat size. Indices of land-cover were calculated from correspondence analyses on land-cover data, fragmentation was estimated with the dendritic connectivity index, and habitat size was calculated as the length of the stream segment (alpha diversity) or the length of the stream network (beta diversity).

Results

Alpha diversity was most strongly related to land-cover variables associated with urban development and agriculture (negative relationship with urbanization). Whereas, beta diversity was most strongly influenced by habitat size (positive relationship) and fragmentation (positive relationship). Turnover was positively correlated with fragmentation and habitat size, whereas species loss was negatively correlated with habitat size.

Conclusions

Land-cover has a larger effect on alpha diversity because it alters the environmental conditions at a site, whereas fragmentation has a larger effect on beta diversity because it affects the movement of individuals among sites. Assessing the cumulative impact of environmental change requires a multiscale approach that simultaneously considers alpha and beta diversity.

     

甘肃金昌市生物多样性保护与建设探讨

生物多样性是人类赖以生存和发展的基础,通过调查分析金昌生物多样性的现状和存在的问题,提出保护生物多样性的措施。     

Landscape genetics since 2003: status,challenges and future directions

A scientific symposium on landscape genetics, held at the 2013 IALE Europe Conference in Manchester UK (September 2–8, 2013), highlighted status, challenges and future avenues in the field. Key topics included analytical aspects in landscape genetics, conceptual progress and application of landscape genetics for conservation management. First, analytical aspects referred to statistical relationships between genetic and landscape data. It was suggested that linear mixed models or Bayesian approaches are particularly promising due to more appropriate and powerful ways for analyzing landscape effects on genetic variation. Second, supplementing neutral genetic variation with adaptive genetic variation is very promising. However, research needs to go beyond the identification of genomic regions under selection and provide information on the ecological function of adaptive genetic regions. Conceptually, endogenous processes (e.g., life-history attributes such as dispersal) require consideration as supplementary factors in shaping the genetic variation in addition to landscapes. Also, the temporal dimension in landscapes for both the past and the future should be given increased attention as the genetic responses to landscape change may be non-simultaneous, resulting in time lags. As for applied conservation management, landscape genetics can provide important baseline information such as basic data on species movement in a spatial context, assessments of the spatial need for management efforts, or evaluations of the effectiveness of already existing management measures.     

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.     

Habitat fragmentation,livelihood behaviors,and contact between people and nonhuman primates in Africa

Landscape Ecology - Deforestation and landscape fragmentation have been identified as processes enabling direct transmission of zoonotic infections. Certain human behaviors provide opportunities...     

Habitat corridors and the conservation of small mammals in a fragmented forest environment

At Naringal in south-western Victoria, Australia, clearing of the original forest environment has created an agricultural landscape dominated by grazed pastures of introduced grasses. Remnant forest vegetation is re-stricted to small patches of less than 100 ha in size, that are loosely linked by narrow forested strips along road reserves and creeks. Six native and two introduced species of small terrestrial mammal (< 2 kg) occur within this environment. The native mammals, being dependent upon forest vegetation, were less tolerant to forest fragmentation than were the introduced species that also persist in farmland and farm buildings. The native mammals displayed an increasing frequency of occurrence in successively larger size-classes of forest patches. Those species with the greatest body-weight were the most vulnerable to habitat loss. All species of small mammal occurred in narrow habitat corridors of forest vegetation on roadsides. The resident status, seasonal variation in relative abundance, patterns of reproduction, and movements of each species were monitored in two habitat corridors during a 25-month trapping study. The corridors were found to facilitate continuity between otherwise-isolated populations of small mammals in this locality in two ways: firstly, by providing a pathway for the dispersal of single animals between patches; and secondly, by enabling gene flow through populations resident within the corridors. The small size of forest remnants at Naringal, and the vulnerability of species with low population sizes, emphasize the importance of preserving a mosaic of numerous habitat patches that together will support regional populations of sufficient size for longer-term persistence. The continuity between remnant habitats that is provided by a network of habitat corridors is an essential, and critical, component of this conservation strategy.     

Changes in land-use/land-cover patterns in Italy and their implications for biodiversity conservation

Land-use/land-cover change is the most important factor in causing biodiversity loss. The Mediterranean region has been affected by antropic disturbance for thousands of years, and is, nowadays, one of the most significantly altered hotspots in the world. However, in the last years a significant increase in forest cover has been measured. These new patterns are independent from planned conservation strategies and appear to have a substantial impact on landscapes and biodiversity. We used three land-use/land-cover maps (from 1960 to 2000) covering the Italian peninsula to analyze the pattern of land-use/land-cover change. We measured an increase in forests, especially in mountains, an increase in artificial areas, especially in coastal zones, and a decrease in pastures. Intensively cultivated areas showed a limited decrease while extensively cultivated ones showed a marked decrease. In the same period mammal and bird species followed a similar pattern, with forest birds, ungulates and carnivores increasing, and typically Mediterranean species decreasing. We suggest that our results may provide important information, which could be useful for conservation planning in the entire Mediterranean hotspot. We suggest that an increasing conservation effort should be made to protect the Mediterranean-type forests and scrublands, as well as traditional agricultural practices. Moreover, future conservation efforts should consider the broad socio-political and ecological processes that are most likely to occur across the whole hotspot, especially along coastal areas, and the network of protected areas should be functionally integrated in a conservation strategy that includes the human-dominated landscape.     

Moving beyond landscape resistance: considerations for the future of connectivity modelling and conservation science

Landscape Ecology - Landscape connectivity, the extent to which a landscape facilitates the flow of ecological processes such as organism movement, has emerged as a central focus of landscape...     

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.