Effects Of Landscape Fragmentation Research Articles

Effects of Landscape Fragmentation on Soil Loss in the Cerrado Biome, Brazil

Soil loss stands as a critical global challenge, posing economic and environmental threats to soil and water conservation. This study aimed to assess the impact of landscape changes on soil loss in the Descoberto River basin, encompassing 62 watersheds in the Cerrado biome in central Brazil. We analysed a 32-year time series (1985-2017) of land use and land cover data based on geostatistical techniques and spatiotemporal weighted regression analysis. Principal component analysis condensed 16 landscape metrics into three factors: aggregation/diversity, dispersion/adjacency, and patchiness. The average annual total soil loss across all 62 analysed watersheds was estimated at 73.3 ± 78.2 (standard deviation) ton ha−1. A significant positive correlation was observed between landscape fragmentation and soil erosion, indicating that, as fragmentation increases, soil losses also increase. Furthermore, our analysis revealed a decreasing trend in soil loss rates in recent years, primarily attributed to the recovery of native vegetation since no significant soil management practices were widely implemented in the study area during the study period.

Study on soil erosion and its driving factors from the perspective of landscape in Xiushui watershed, China

Soil erosion (SE) is one of the most serious disasters in the world, which directly damage the productivity of the land and affect human well-being. How to effectively mitigate soil erosion is a challenge faced by all countries in the world. In this study, soil erosion was quantitatively assessed base on the RULSE model in an ecologically fragile area [Xiushui watershed (XSW)], and the effects of three major categories of factors (land use/cover change, landscape fragmentation and climate) on soil erosion were investigated using correlation analysis and structural equation model. The results indicated that there was no continuous increase or decrease trend on the SE of XSW with impact of rainfall, the mean values of SE were 2205.27 t/ha, 3414.25 t/ha and 3319.44 t/ha from 2000 to 2020 and the hot areas of SE were mainly distributed around the Xiushui river channel, respectively. The expansion of urbanization (the area of impervious increased from 113.12 to 252.57 km2) aggravated landscape fragmentation, and the landscape fragmented area had some overlap with the hot zone of SE. Additionally, the LUCC factor dominated by NDVI, landscape fragmentation factor and climate factor dominated by rainfall had a directly driving effect on SE, where the path coefficient of landscape fragmentation was 0.61 (P < 0.01), respectively. We also found that except increasing forest area, improving forest quality (NDVI, canopy closure, structure) deserved emphasized in SE management, and the effect of landscape fragmentation on SE also should not be ignored. Moreover, soil erosion assessment at large scales over long time periods tends to underestimate the driving force of rainfall on SE, and it is a great challenge to evaluate the effect of extreme rainfall on soil erosion at short time scales in a downscale manner. This research provides insights for ecological sustainable management and soil erosion protection policies.

Neighboring Effects on Ecological Functions: A New Approach and Application in Urbanizing China

Rapid urbanization has widely induced fragmented landscapes and further negatively affected ecological functions. The edge effect is an approach commonly used to investigate these negative impacts. However, edge effect research tends to focus on the impacts that a certain landscape receives from its adjacent lands rather than to assess all the influences of the landscape edges in a region, even though the latter is critical for regional ecological planning. To fill in this gap, the concept of neighboring effect is raised and analyzed in this paper with a case study of Xintai City in Northern China. Results show that the neighboring effects are generally negative for ecological functions, especially in regions that experience rapid urbanization or heavy human activities. The U-shaped relationship between the neighboring effect of a patch and its distance to the nearest township center indicates that the border region of urban and built-up areas suffers the most negative influences due to the intense interactions between different land uses. The heterogeneous effects of influencing factors in urban and rural areas were revealed by the regression results. Socioeconomic development has more important influence on neighboring effects on ecological functions in rural areas than in urban areas, and local cadres’ support of environmental protection matters only in rural areas for a less ecological functional loss. This study quantitatively examined the negative ecological effects of landscape fragmentation during rapid urbanization and calls for more attention to ecological planning at the local scale.

Effect of landscape fragmentation on soil quality and ecosystem services in land use and landform types

This study was carried out to model the ecosystem services, i.e., habitat quality, carbon storage, nutrient export, and soil export using the InVEST software and soil quality through the integrated quality index across Shoor River basin, southwestern Iran, as well as their relationships to landscape metrics using the Pearson’s correlation and ordered least square regression. The interactions between ecosystem services efficiency, soil quality and landscape fragmentation were also evaluated using the ternary analysis. The results showed that the northern and eastern parts of the study area had more suitability to provide soil quality, habitat quality, carbon storage, and ecosystem service efficiency than the southern and western parts while this trend was the opposite for soil and nutrient exports. The highest soil quality, habitat quality, carbon storage, and ecosystem services efficiency were calculated for the forest's land use and the ridge/tops landform. The highest nutrient and soil exports were also seen in agriculture and rangeland land uses, respectively, as well as for plain and ridge/top landforms, respectively. Statistical analysis confirmed that there were positive and moderate relationships between soil quality to habitat quality and carbon storage and no certain relationships to soil and nutrient export. Moreover, patch density had a negative impact on habitat quality, carbon storage, soil quality, and ecosystem services efficiency and a positive effect on soil and nutrient exports. This trend was the opposite for the largest patch index, patch cohesion index, and effective mesh size. The findings demonstrated that increasing the landscape fragmentation decreased soil quality, habitat quality, carbon storage, and ecosystem services efficiency but increased nutrient and soil exports. Furthermore, the interactions between ecosystem services efficiency, soil quality, and landscape fragmentation were changed under the influence of the dominant land use and landform types across the sub-basins of the study area.

The effect of landscape fragmentation on Turing-pattern formation.

Diffusion-driven instability and Turing pattern formation are a well-known mechanism by which the local interaction of species, combined with random spatial movement, can generate stable patterns of population densities in the absence of spatial heterogeneity of the underlying medium. Some examples of such patterns exist in ecological interactions between predator and prey, but the conditions required for these patterns are not easily satisfied in ecological systems. At the same time, most ecological systems exist in heterogeneous landscapes, and landscape heterogeneity can affect species interactions and individual movement behavior. In this work, we explore whether and how landscape heterogeneity might facilitate Turing pattern formation in predator-prey interactions. We formulate reaction-diffusion equations for two interacting species on an infinite patchy landscape, consisting of two types of periodically alternating patches. Population dynamics and movement behavior differ between patch types, and individuals may have a preference for one of the two habitat types. We apply homogenization theory to derive an appropriately averaged model, to which we apply stability analysis for Turing patterns. We then study three scenarios in detail and find mechanisms by which diffusion-driven instabilities may arise even if the local interaction and movement rates do not indicate it.

Conservation of hoverflies (Diptera, Syrphidae) requires complementary resources at the landscape and local scales.

Accumulating evidence shows that landscape fragmentation drives the observed worldwide decline in populations of pollinators, particularly in species of Lepidoptera and Hymenoptera. However, Little is known about the effects of landscape fragmentation on hoverfly (Diptera, Syrphidae) communities. Hoverflies provide varied ecosystem services: larvae contribute to waste decomposition (saprophagous species) and pest control (aphidophagous species), and adults pollinate a wide range of flowers.To determine how the diversity and quantity of resources for larvae and adults affect hoverfly abundance and species richness at three spatial scales, we recorded insect visitors of five target plant species in Belgian heathlands, habitats that have decreased considerably due to human activities.Hoverflies represented the most abundant visitors on two plant species, and the second most abundant visitors (after bumblebees) on the other target plant species. A large proportion of hoverflies observed were aphidophagous species associated with coniferous and deciduous forests. Resources for the larvae and floral resources for the adults influenced interactions among hoverflies and plants, but acted at different scales: larval habitat availability (distance to larval habitat) was relevant at the landscape scale, whereas adult resource availability (floral density) was relevant at the plot scale.Hoverfly abundance and species richness decreased with distance to larval habitat but increased with floral density. Moreover, landscape structure and composition had different effects according to hoverfly ecological traits. Landscape composition influenced aphidophagous but not saprophagous hoverflies, in that their abundance and species richness decreased with distance to forests. Maintenance of the interactions between plants and their hoverfly visitors requires complementary resources at both landscape and local scales.

Effects of landscape fragmentation on genetic diversity and population structure of Red deer (Cervus elaphus) in Northern Germany

Effects of landscape fragmentation on genetic diversity and population structure of Red deer (Cervus elaphus) in Northern Germany

Effects of Landscape Fragmentation, Habitat, and Vegetation on Abundance of Ixodesscapularis as a Lyme Disease Carrier in Essex County, Massachusetts

The blacklegged tick (Ixodes scapularis) is the main vector for the Lyme disease‐causing spirochete Borrelia burgdorferi, which is transmitted to humans through the tick's bite. One explanation for the increased incidences in Lyme disease and tick abundance in the Northeast is fragmentation, in which continuous forest is transformed into small isolated patches. This study sought to connect landscape, habitat, and vegetation variables with Lyme disease prevalence. We monitored tick abundance among larva, nymph, and adult stages at 16 study sites representing 4 different habitat types (natural edge, pasture edge, residential edge, interior forest) in Essex County, MA. In order to detect the etiologic agent, B. burgdorferi, we isolated DNA and performed nested PCR to the 16S‐23S rRNA intergenic spacer region. Results showed that larvae correlated positively with % vegetation cover, total basal area (TBA) deciduous, and tree richness, but negatively to coniferous density. Nymphs demonstrated a positive relationship with % vegetation cover, TBA deciduous, and tree richness, but a negative relationship with coniferous density, deciduous density, and leaf litter. At a landscape scale, adults showed a positive relationship to human edge (forest edge created by humans) within a 500 m radius of the sampling point. Based on preliminary results, nested PCR has yielded adult ticks positive for B. burgdorferi, but additional data is needed in order to determine the relationship between Lyme disease prevalence and landscape, habitat, and vegetation variables. This work is supported by internal funding from Gordon College.

Effects of Landscape Fragmentation and Climate on Lyme Disease Incidence in the Northeastern United States

Lyme disease is the most frequently reported vector borne illness in the United States, and incidences are increasing steadily year after year. This study explores the influence of landscape (e.g., land use pattern and landscape fragmentation) and climatic factors (e.g., temperature and precipitation) at a regional scale on Lyme disease incidence. The study area includes thirteen states in the Northeastern United States. Lyme disease incidence at county level for the period of 2002-2006 was linked with several key landscape and climatic variables in a negative binomial regression model. Results show that Lyme disease incidence has a relatively clear connection with regional landscape fragmentation and temperature. For example, more fragmentation between forests and residential areas results in higher local Lyme disease incidence. This study also indicates that, for the same landscape, some landscape variables derived at a particular scale show a clearer connection to Lyme disease than do others. In general, the study sheds more light on connections between Lyme disease incidence and climate and landscape patterns at the regional scale. Integrating findings of this regional study with studies at a local scale will further refine understanding of the pattern of Lyme disease as well as increase our ability to predict, prevent, and respond to disease.

Development of genetic diversity, differentiation and structure over 500 years in four ponderosa pine populations

Population history plays an important role in shaping contemporary levels of genetic variation and geographic structure. This is especially true in small, isolated range-margin populations, where effects of inbreeding, genetic drift and gene flow may be more pronounced than in large continuous populations. Effects of landscape fragmentation and isolation distance may have implications for persistence of range-margin populations if they are demographic sinks. We studied four small, disjunct populations of ponderosa pine over a 500-year period. We coupled demographic data obtained through dendroecological methods with microsatellite data to discern how and when contemporary levels of allelic diversity, among and within-population levels of differentiation, and geographic structure, arose. Alleles accumulated rapidly following initial colonization, demonstrating proportionally high levels of gene flow into the populations. At population sizes of approximately 100 individuals, allele accumulation saturated. Levels of genetic differentiation among populations (F(ST) and Jost's D(est)) and diversity within populations (F(IS)) remained stable through time. There was no evidence of geographic genetic structure at any time in the populations' history. Proportionally, high gene flow in the early stages of population growth resulted in rapid accumulation of alleles and quickly created relatively homogenous genetic patterns among populations. Our study demonstrates that contemporary levels of genetic diversity were formed quickly and early in population development. How contemporary genetic diversity accumulates over time is a key facet of understanding population growth and development. This is especially relevant given the extent and speed at which species ranges are predicted to shift in the coming century.

Individual‐based movement models reveals sex‐biased effects of landscape fragmentation on animal movement

Animal movement and behavior may respond to habitat modification or fragmentation in non trivial ways, thereby strongly conditioning the fate of populations. This study aims to understand movement patterns of non‐dispersal animals in both natural and altered landscapes, using the endangered terrestrial tortoise Testudo graeca as example. We used individual‐based simulation models representing competing hypotheses on tortoise movement. Model parameterization and selection was based on radiotracking data and an inverse approach that is able to deal with observation uncertainty, individual variability, and process stochasticity. We find that land use intensification had a strong impact on the movement and behavior of non‐dispersing individuals of T. graeca. In natural landscapes, males and females showed a similar movement and behavior profile with a strong home behavior component, and little individual variability. However, in altered landscapes, movement and behavior greatly varied among individuals, particularly in females, and males and females showed different movement patterns. Females showed a wide range of movement patterns, from strong home behavior to an unbounded movement. Our study shows that population or movement models that assume single behavioral states for animals inhabiting different landscape structures can be strongly misleading and, furthermore, that the impact of landscape modification on movement and behavioral patterns can be strongly sex‐biased. Flexible, individual‐based movement models coupled with inverse parameterization and model selection approaches proved useful in understanding the mechanisms controlling animal movement patterns.

Predicting Landscape-Genetic Consequences of Habitat Loss, Fragmentation and Mobility for Multiple Species of Woodland Birds

Inference concerning the impact of habitat fragmentation on dispersal and gene flow is a key theme in landscape genetics. Recently, the ability of established approaches to identify reliably the differential effects of landscape structure (e.g. land-cover composition, remnant vegetation configuration and extent) on the mobility of organisms has been questioned. More explicit methods of predicting and testing for such effects must move beyond post hoc explanations for single landscapes and species. Here, we document a process for making a priori predictions, using existing spatial and ecological data and expert opinion, of the effects of landscape structure on genetic structure of multiple species across replicated landscape blocks. We compare the results of two common methods for estimating the influence of landscape structure on effective distance: least-cost path analysis and isolation-by-resistance. We present a series of alternative models of genetic connectivity in the study area, represented by different landscape resistance surfaces for calculating effective distance, and identify appropriate null models. The process is applied to ten species of sympatric woodland-dependant birds. For each species, we rank a priori the expectation of fit of genetic response to the models according to the expected response of birds to loss of structural connectivity and landscape-scale tree-cover. These rankings (our hypotheses) are presented for testing with empirical genetic data in a subsequent contribution. We propose that this replicated landscape, multi-species approach offers a robust method for identifying the likely effects of landscape fragmentation on dispersal.

The effects of landscape fragmentation on pollination dynamics: absence of evidence not evidence of absence

Animal-mediated pollination is essential for both ecosystem services and conservation of global biodiversity, but a growing body of work reveals that it is negatively affected by anthropogenic disturbance. Landscape-scale disturbance results in two often inter-related processes: (1) habitat loss, (2) disruptions of habitat configuration (i.e. fragmentation). Understanding the relative effects of such processes is critical in designing effective management strategies to limit pollination and pollinator decline. We reviewed existing published work from 1989 to 2009 and found that only six of 303 studies considering the influence of landscape context on pollination separated the effects of habitat loss from fragmentation. We provide a synthesis of the current landscape, behavioural, and pollination ecology literature in order to present preliminary multiple working hypotheses explaining how these two landscape processes might independently influence pollination dynamics. Landscape disturbance primarily influences three components of pollination interactions: pollinator density, movement, and plant demography. We argue that effects of habitat loss on each of these components are likely to differ substantially from the effects of fragmentation, which is likely to be more complex and may influence each pollination component in contrasting ways. The interdependency between plants and animals inherent to pollination systems also has the possibility to drive cumulative effects of fragmentation, initiating negative feedback loops between animals and the plants they pollinate. Alternatively, due to their asymmetrical structure, pollination networks may be relatively robust to fragmentation. Despite the potential importance of independent effects of habitat fragmentation, its effects on pollination remain largely untested. We postulate that variation across studies in the effects of 'fragmentation' owes much to artifacts of the sampling regimes adopted, particularly (1) incorrectly separating fragmentation from habitat loss, and (2) mis-matches in spatial scale between landscapes studied and the ecological processes of interest. The field of landscape pollination ecology could be greatly advanced through the consideration and quantification of the matrix, landscape functional connectivity, and pollinator movement behaviour in response to these elements. Studies designed to disentangle the independent effects of habitat loss and fragmentation are essential for gaining insight into landscape-mediated pollination declines, implementing effective conservation measures, and optimizing ecosystem services in complex landscapes.

Does Landscape Fragmentation Influence Sex Ratio of Dioecious Plants? A Case Study of Pistacia chinensis in the Thousand-Island Lake Region of China

The Thousand-Island Lake region in Zhejiang Province, China is a highly fragmented landscape with a clear point-in-time of fragmentation as a result of flooding to form the reservoir. Islands in the artificial lake were surveyed to examine how population sex ratio of a dioecious plant specie Pistacia chinensis B. was affected by landscape fragmentation. A natural population on the mainland near the lake was also surveyed for comparison. Population size, sex ratio and diameter at breast height (DBH) of individuals were measured over 2 years. More than 1,500 individuals, distributed in 31 populations, were studied. Soil nitrogen in the different populations was measured to identify the relationship between sex ratio and micro-environmental conditions. In accordance with the results of many other reports on biased sex ratio in relation to environmental gradient, we found that poor soil nitrogen areas fostered male-biased populations. In addition, the degree of sex ratio bias increased with decreasing population size and population connectivity. The biased sex ratios were only found in younger individuals (less than 50 years old) in small populations, while a stable 1∶1 sex ratio was found in the large population on the mainland. We concluded that the effects of landscape fragmentation on the dioecious population sex ratio were mainly achieved in relation to changing soil nitrogen conditions in patches and pollen limitation within and among populations. Large populations could maintain a more suitable environment in terms of nutrient conditions and pollen flow, subsequently maintaining a stable sex ratio in dioecious plant populations. Both micro-environmental factors and spatial structure should be considered in fragmented landscape for the conservation of dioecious plant species.

Landscape disturbance causes small-scale functional homogenization, but limited taxonomic homogenization, in plant communities

Summary 1. Biotic homogenization (BH), a dominant process shaping the response of natural communities to human disturbance, reflects both the expansion of exotic species at large scales and other mechanisms that often operate at smaller scales. 2. Here, we examined the relationship between BH in plant communities and spatio-temporal landscape disturbance (habitat fragmentation and surrounding habitat conversion) at a local scale (1 km²), using data from a standardized monitoring programme in France. We quantified BH using both a spatial partitioning of taxonomic diversity and the average habitat specialization of communities, which informs on functional BH. 3. We observed a positive relationship between local taxonomic diversity and landscape fragmentation or instability. This increase in local taxonomic diversity was, however, paralleled by a decrease in average community specialization in more fragmented landscapes and in more unstable landscapes around forest sites. The decrease in average community specialization suggests that landscape disturbance causes functional BH, but there was limited evidence for concurrent taxonomic BH. 4. Synthesis. Our results show that landscape disturbance is partly responsible for functional BH at small scales via the extirpation of specialist species, with possible consequences for ecosystem functioning. However, this change in community composition is not systematically associated with taxonomic BH. This has direct relevance in designing biodiversity indicators: metrics incorporating species sensitivity to disturbance (such as species specialization to habitat) appear much more reliable than taxonomic diversity for documenting the response of communities to disturbance.

Integer programming for optimizing habitat network permeability

PurposeNegative effects of habitat isolation that arise from landscape fragmentation can be mitigated, by connecting natural areas through a network of habitat corridors. To increase the permeability of a given network, i.e. to decrease the resistance to animal movements through this network, often many developments can be made. The available financial resources being limited, the most effective developments must be chosen. This optimization problem, suggested in Finke and Sonnenschein, can be treated by heuristics and simulation approaches, but the method is heavy and the obtained solutions are sub‐optimal. The aim of the paper is to show that the problem can be efficiently solved to optimality by mathematical programming.Design/methodology/approachThe moves of the individual in the network are modeled by an absorbing Markov chain and the development problem is formulated as a mixed‐integer quadratic program, then this program is linearized, and the best developments to make are determined by mixed‐integer linear programming.FindingsFirst, the approach allows the development problem to be solved to optimality contrary to other methods. Second, the definition of the mathematical program is relatively simple, and its implementation is immediate by using standard, commercially available, software. Third, as it is well known with mixed‐integer linear programming formulation it is possible to add new constraints easily if they are linear (or can be linearized).Research limitations/implicationsWith a view to propose a simple and efficient tool to solve a difficult combinatorial optimization problem arising in the improvement of permeability across habitat networks, the approach has been tested on simulated habitat networks. The research does not include the study of some precise species movements in a real network.Practical implicationsThe results provide a simple and efficient decision‐aid tool to try to improve the permeability of habitat networks.Originality/valueThe joint use of mathematical programming techniques and Markov chain theory is used to try to lessen the negative effects of landscape fragmentation.

Influence of landscape pattern on breeding distribution and success in a threatened Alcid, the marbled murrelet: model transferability and management implications

Summary The marbled murrelet Brachyramphus marmoratus is a threatened Alcid nesting in old‐growth coastal forests from central California to Alaska. Logging has greatly reduced the amount and altered the pattern of the species’ nesting habitat. Landscape fragmentation effects on the breeding ecology of the species are poorly understood because of the inaccessibility of nest sites. Using radio‐telemetry, 157 marbled murrelet nests were located in two old‐growth areas in British Columbia, Canada, with different logging histories. Probable breeding success was estimated from nest attendance patterns by radio‐tagged parents. Information‐theoretic and hypothesis‐testing methods were used to model breeding distribution (used vs. random unknown sites) and success (successful vs. failed nests) within c. 50‐km radius extents at a scale of 2·3‐km radius landscapes. Intersite transferability of distribution models was tested. Breeding distribution was positively related with old‐growth patch proximity, edge density (natural and artificial) and contrast, proportion of landscape under old‐growth or core habitat, and interspersion of old‐growth patches; it was negatively related with coastal zone proximity and mean old‐growth patch size. Breeding success was negatively affected by the edge contrast, coast proximity and proportion of young forest, probably reflecting the distribution of nest predators. All distribution models discriminated well between used and random landscapes within the training area. Intersite model transferability was good for 50% of the models. The models less predictive of the training site (area under the curve 0·676–0·738) were more transferable, probably because at the training site, which had considerably less old‐growth nesting habitat (18% of extent) than the testing site (55%), breeding distribution was driven by a different subset of predictors. Synthesis and applications. Geographic information system (GIS) data were helpful in discriminating between landscapes known to be used by nesting marbled murrelets and those with unknown breeding status. Previous indirect inferences about landscape‐level effects on breeding distribution in the birds were shown to correspond with their true nesting distribution. Our results suggest that habitat fragmentation per se need not have a negative effect on the birds beyond that as a result of habitat loss, unless associated with an increased abundance of predators. Our results fine‐tune the existing habitat conservation guidelines by suggesting that protection of old‐growth forest adjacent to clearcuts is important. We provide a means for desktop classification of marbled murrelet landscapes. We advise the application of several different models, depending on the amount of remaining old‐growth forest, to evaluate the consistency of predictions.

TESTS OF LANDSCAPE INFLUENCE: NEST PREDATION AND BROOD PARASITISM IN FRAGMENTED ECOSYSTEMS

The effects of landscape fragmentation on nest predation and brood parasitism, the two primary causes of avian reproductive failure, have been difficult to generalize across landscapes, yet few studies have clearly considered the context and spatial scale of fragmentation. Working in two river systems fragmented by agricultural and rural-housing development, we tracked nesting success and brood parasitism in > 2500 bird nests in 38 patches of deciduous riparian woodland. Patches on both river systems were embedded in one of two local contexts (buffered from agriculture by coniferous forest, or adjacent to agriculture), but the abundance of agriculture and human habitation within 1 km of each patch was highly variable. We examined evidence for three models of landscape effects on nest predation based on (1) the relative importance of generalist agricultural nest predators, (2) predators associated with the natural habitats typically removed by agricultural development, or (3) an additive combination of these two predator communities. We found strong support for an additive predation model in which landscape features affect nest predation differently at different spatial scales. Riparian habitat with forest buffers had higher nest predation rates than sites adjacent to agriculture, but nest predation also increased with increasing agriculture in the larger landscape surrounding each site. These results suggest that predators living in remnant woodland buffers, as well as generalist nest predators associated with agriculture, affect nest predation rates, but they appear to respond at different spatial scales. Brood parasitism, in contrast, was unrelated to agricultural abundance on the landscape, but showed a strong nonlinear relationship with farm and house density, indicating a critical point at which increased human habitat causes increased brood parasitism. Accurate predictions regarding landscape effects on nest predation and brood parasitism will require an increased appreciation of the multiple scales at which landscape components influence predator and parasite behavior.

Using landscape ecology to evaluate an alternative management scenario in abandoned Mediterranean mountain areas

The main characteristic of landscape evolution in the Pyrenees during the 20th century is the increased presence of shrubs in old fields. Revegetation is mainly recorded on medium and low slopes because of land abandonment. The increase in shrubs causes the loss of grazing resources during winter, landscape homogenization and an increase in fire risk. The objective of this paper was to create a scenario for land use change by combining Geographical Information Systems (GIS) and Landscape Ecology Analysis (LEA). To improve the present seasonal imbalance in pastoral resources, the scenario proposes to convert shrubland areas to grasslands without an excessive increase in soil erosion or landscape fragmentation. The results obtained indicate that the strategy produces greater landscape diversity and an increase in annual pasture resources (16.7%), which exceeds 60% of total in winter. The effects of landscape fragmentation on biodiversity, fire risk control and the imbalance of pastures are discussed. The scenario would improve extensive livestock farming, which is the most important economic activity in this area and other Mediterranean mountains.

Louisiana’s Wetlands: A Lesson in Nature Appreciation

Hurricane Katrina’s disastrous flooding of the Gulf Coast confirmed three decades of warnings by scientists. Most of New Orleans is below sea level, and South Louisiana’s coastal wetlands, which once helped buffer the city from giant storms, have been disappearing at a spectacularly swift pace. Now some researchers are calling for restoration of wetlands and barrier islands to help protect New Orleans the next time a hurricane strikes. An average of 34 square miles of South Louisiana land, mostly marsh, has disappeared each year for the past five decades, according to the U.S. Geological Survey (USGS). As much as 80% of the nation’s coastal wetland loss in this time occurred in Louisiana. From 1932 to 2000, the state lost 1,900 square miles of land to the Gulf of Mexico. By 2050, if nothing is done to stop this process, the state could lose another 700 square miles, and one-third of 1930s coastal Louisiana will have vanished. Importantly, New Orleans and surrounding areas will become ever more vulnerable to future storms. “New Orleans can’t be restored unless we also address coastal and wetland restoration too,” says Craig E. Colten, a geographer at Louisiana State University (LSU).