Influence of landscape structure on reef fish assemblages

Management of tropical marine environments calls for interdisciplinary studies and innovative methodologies that consider processes occurring over broad spatial scales. We investigated relationships between landscape structure and reef fish assemblage structure in the US Virgin Islands. Measures of landscape structure were transformed into a reduced set of composite indices using principal component analyses (PCA) to synthesize data on the spatial patterning of the landscape structure of the study reefs. However, composite indices (e.g., habitat diversity) were not particularly informative for predicting reef fish assemblage structure. Rather, relationships were interpreted more easily when functional groups of fishes were related to individual habitat features. In particular, multiple reef fish parameters were strongly associated with reef context. Fishes responded to benthic habitat structure at multiple spatial scales, with various groups of fishes each correlated to a unique suite of variables. Accordingly, future experiments should be designed to test functional relationships based on the ecology of the organisms of interest. Our study demonstrates that landscape-scale habitat features influence reef fish communities, illustrating promise in applying a landscape ecology approach to better understand factors that structure coral reef ecosystems. Furthermore, our findings may prove useful in design of spatially-based conservation approaches such as marine protected areas (MPAs), because landscape-scale metrics may serve as proxies for areas with high species diversity and abundance within the coral reef landscape.     

Influence of landscape structure on reef fish assemblages

Management of tropical marine environments calls for interdisciplinary studies and innovative methodologies that consider processes occurring over broad spatial scales. We investigated relationships between landscape structure and reef fish assemblage structure in the US Virgin Islands. Measures of landscape structure were transformed into a reduced set of composite indices using principal component analyses (PCA) to synthesize data on the spatial patterning of the landscape structure of the study reefs. However, composite indices (e.g., habitat diversity) were not particularly informative for predicting reef fish assemblage structure. Rather, relationships were interpreted more easily when functional groups of fishes were related to individual habitat features. In particular, multiple reef fish parameters were strongly associated with reef context. Fishes responded to benthic habitat structure at multiple spatial scales, with various groups of fishes each correlated to a unique suite of variables. Accordingly, future experiments should be designed to test functional relationships based on the ecology of the organisms of interest. Our study demonstrates that landscape-scale habitat features influence reef fish communities, illustrating promise in applying a landscape ecology approach to better understand factors that structure coral reef ecosystems. Furthermore, our findings may prove useful in design of spatially-based conservation approaches such as marine protected areas (MPAs), because landscape-scale metrics may serve as proxies for areas with high species diversity and abundance within the coral reef landscape.

     

The influence of connectivity on richness and temporal variation of reef fishes

To test the effects of connectivity on fish diversity in isolated reef patches we deployed pairs of artificial reefs (AR) at constant distances (12 and 25 m) from a large continuous reef and added series of small ARs to half of them. These small reefs served as stepping-stones to increase fish movement between the large ARs and the continuous reef. Species gain and loss curves were compared to obtain deeper understanding of the underlying mechanisms in relation to the theory of island biogeography. We found that AR without stepping-stones maintained up to 57-fold more individuals than ARs with stepping-stones during mass recruitment events that were dominated by the family Apogonidae. However, in-between these mass recruitment events the overall impact of the stepping-stones on richness and abundance was small. By contrast, increasing distance from the continuous reef from 12 to 25 m increased fish richness, although this was confounded with time since AR deployment. Increase in richness with distance was predominantly caused by elevated species gain. Our results suggest that fish assemblages respond in distinct ways to two types of isolation: (1) Increased richness with distance from a continuous reef, and (2) increased fluctuation in abundance with decreased connectivity. The latter may be the outcome of accumulation and then abrupt emigrations of fishes from isolated reefs. This study confirms that the spatial setting of reef patches in relation to larger or continuous reefs alters fish assemblages, which may be important for planning AR deployments that maximizes diversity.     

Habitat connectivity and complexity underpin fish community structure across a seascape of tropical macroalgae meadows

Context

In heterogeneous landscapes, local patterns of community structure are a product of the habitat size and condition within a patch interacting with adjacent habitat patches of varying composition and quantity. While evidence for local versus landscape factors have been found in terrestrial biomes, support for such multi-scale effects shaping marine ecological communities is equivocal.

Objectives

We investigated whether within-patch habitat condition can override seascape context to explain the community structure of macroalgae-associated reef fishes across a tropical seascape.

Methods

We mapped the distribution and abundance of a diverse family of reef fishes (Labridae) occupying macroalgae meadows within a tropical reef ecosystem, and using best-subsets model selection, investigated the potential for habitat structural connectivity and/or local habitat quality for predicting variations in fish community structure across the seascape.

Results

Local habitat quality (canopy structure, hard habitat complexity) and area of coral-dominated habitat within 500 m of a macroalgal meadow provided the best predictors of fish community structure. However, the specific importance of a given predictor varied with fish life history stage and functional trophic group. Interestingly, macroalgae meadow area was among the least important predictors.

Conclusions

Given the complex interplay between local habitat quality and spatial context effects on fish biodiversity, our study reveals the multi-scale predictors that should be used in spatial conservation and management approaches for tropical fish diversity. Moreover, our findings question the ubiquity of habitat area effects in patchy landscapes, and cautions against a sole reliance on habitat quantity in spatial management.

     

Models to distinguish effects of landscape patterns and human population pressures associated with species loss in Canadian national parks

It is widely accepted that large protected areas are required to effectively conserve historical species composition. However, recent analyses of mammal species loss in Canadian and African national parks contradict earlier conclusions that extent of local extinctions (i.e., extirpations) is strongly inversely related to park size, suggesting that park size alone is inadequate to predict reserve designs that may sustain biodiversity. To plan protected areas that will meet conservation goals, reserve-design models that incorporate other landscape-scale factors in addition to reserve area are needed; potential factors include the types and intensity of land use and habitat change, together with land cover types, in and around parks. Additionally, human population size around parks, and visitor density in parks may affect species loss. We quantified land use, land cover, and human population in and around 24 Canadian national parks to model effects of human disturbance and changes in natural habitats on known mammal extirpations.Multiple regression models were compared using the Akaike Information Criterion (AIC_c). The most parsimonious model (AIC_c weighting w _i = 0.5391) emphasized effective habitat area in and around parks and not visitor numbers nor human population size around parks. Our model suggests that parks with as little as 3140 km² of effective habitat area inside may be large enough to conserve historical mammal species composition if they are also surrounded by at least 18 000 km² of effective habitat within 50 km of park boundaries.     

Effects of landscape structure and forest reserve location on old-growth forest bird species in Northern Finland

Old-growth forest birds in Fennoscandia have sharply declined in numbers during the last decades apparently due to commercial forest harvesting and fragmentation of old-growth forests. Conservation measures have led to the establishment of a forest reserve network to assure the persistence of forest birds at a regional scale. However, little is known about the effects of landscape structure within and around the reserves on the distribution of old-growth forest birds. We used a hierarchical approach to address the questions of how landscape structure and composition within forest reserves, landscape composition of surrounding areas and reserve location affect the abundance of resident, old-growth forest birds in the Northern Finnish forest reserve network. The positive role of particular landscape features on bird distribution indicates that both the proportion of old-growth forests and the structure of boreal landscape mosaic has an important role in determining the distribution of these birds. The landscape composition surrounding the reserves proved to be only a weak predictor in species distribution models, which argues against the primary role of the surrounding matrix in determining species distribution within forest reserves. Reserves located near the Russian border showed a higher abundance of old-growth birds than more western ones. Once east-west gradients in overall landscape composition had been accounted for, however, reserves did not differ significantly in the number of species present. These results suggest that landscape gradients, rather than ecological processes such as the presence of source areas located along the border with Russia, are the main determinant of the distribution of old-growth forest birds in the Finnish reserve network. We propose that to enhance regional persistence of old-growth forest birds, conservation efforts should be primarily directed towards the protection and enhancement of forest habitat quality and natural heterogeneity of landscapes within targeted areas. This revised version was published online in July 2006 with corrections to the Cover Date.     

Habitat proximity exerts opposing effects on key ecological functions

Context

Connectivity is an important property of landscapes that shapes populations and ecosystem functioning. We do not know, however, whether and how different types of spatial linkages combine to influence ecological functions, and this hampers their integration into conservation planning.

Objectives

We used coral reef seascapes in eastern Australia as a model system to test whether the proximity of other reefs (habitat proximity) or the proximity of other habitats (seascape proximity) exert stronger effects on two key ecological functions (herbivory and piscivory).

Methods

We measured rates of herbivory (on fleshy macroalgae) and piscivory (on prey fish) on reefs that differed in their proximity to both other reefs and nearby mangroves and seagrass.

Results

The extent of habitat proximity between reefs significantly influenced both ecological functions, but in different ways: isolated reefs supported high herbivory but low piscivory, whilst, conversely, reefs that were closer to other reefs supported high piscivory but low herbivory. This was not caused by herbivores avoiding their predators, as the dominant piscivores (small predatory snappers) were too small to consume the dominant herbivores (large rabbitfishes). Seascape proximity (e.g., distance to mangroves or seagrass) was less important in shaping ecological functions on reefs in this system.

Conclusions

We suggest that the effects of seascape configuration on ecological functions depends on the type of spatial linkage, and the ecological functions in question. To better integrate connectivity into conservation, we must develop a deeper understanding of how different spatial linkages combine to shape ecosystem functioning across landscapes.

     

Testing source-sink theory: the spill-over of mussel recruits beyond marine protected areas

Source-sink theory has contributed to our understanding of the function of protected areas, particularly due to their role as population sources. Marine reserves are a preferred management tool for the conservation of natural populations, creating areas of good quality habitat and thus improving population connectivity by enhancing larval supply and recruitment among shores. Despite recent advances in the study of protected areas in the context of the source-sink theory, rigorous and empirical testing of marine reserves as metapopulation sources for the adjacent areas remain largely unexplored. We investigated the role of marine reserves as population sources, whether there was spill-over beyond the reserve boundaries and if so, whether spill-over was directional. We measured percentage cover and recruitment of mussels (Perna perna) at two reserves and two comparably sized exploited control areas on the south-east coast of South Africa where unprotected populations are severely affected by artisanal exploitation. Adult abundances were enhanced within reserves, but decreased towards their edges. We predicted that recruitment would mirror adult abundances and show directionality, with northern shores having greater recruitment following the prevalent northward flow of near-shore currents. There were, however, no correlations between adult abundances and recruitment for any months or shores, and no clear spatial patterns in recruitment (i.e. similar patterns occurred at reserves and controls). The results emphasise that, while reserves may act as important refuges by protecting adult abundances, their influence on promoting recovery of near-by exploited shores through larval spill-over may be overestimated.     

Context is more important than habitat type in determining use by juvenile fish

Context

Habitat characteristics are often equated with habitat function for animals. However, in heterogeneous landscapes, similar habitat types occur in different environmental contexts. In the marine realm, landscape studies have been confined to particular environments, rather than encompassing entire seascapes, due to incompatible sampling methods required in different situations.

Objectives

We examined the interactive structuring effects of local habitat characteristics and environmental context on assemblage composition.

Methods

We used a single technique—remote underwater video census—to explore the importance of habitat type (biotic structural components, substrate, and depth) and environmental context (marine vs estuarine) in structuring juvenile fish assemblages throughout an entire coastal region. In this model system, a range of structural habitat types were present in both estuarine and marine contexts.

Results

The 1315 video surveys collected show a clear hierarchy in the organisation of juvenile fish communities, with assemblages first distinguished by environmental context, then by habitat type. Marine and estuarine mangroves contained entirely different assemblages, and likewise for rocky reefs and submerged aquatic vegetation. Our results suggest that two functionally different ‘seascape nursery’ types exist at local scales within a single region, defined by their context.

Conclusions

The context of a location can be of greater significance in determining potential habitat function than what habitat-forming biota and substrates are present, and apparently similar habitat types in different contexts may be functionally distinct. These findings have important implications for local-scale management and conservation of juvenile fish habitats, particularly in regard to offsetting and restoration.

     

Landscape influences on stream biotic integrity assessed at multiple spatial scales

The biological integrity of stream ecosystems depends critically on human activities that affect land use/cover along stream margins and possibly throughout the catchment. We evaluated stream condition using an Index of Biotic Integrity (IBI) and a habitat index (HI), and compared these measures to landscape and riparian conditions assessed at different spatial scales in a largely agricultural Midwestern watershed. Our goal was to determine whether land use/cover was an effective predictor of stream integrity, and if so, at what spatial scale. Twenty-three sites in first-through third-order headwater streams were surveyed by electrofishing and site IBIs were calculated based on ten metrics of the fish collection. Habitat features were characterized through field observation, and site HIs calculated from nine instream and bank metrics. Field surveys, aerial photograph interpretation, and geographic information system (GIS) analyses provided assessments of forested land and other vegetation covers at the local, reach, and regional (catchment) scales. The range of conditions among the 23 sites varied from poor to very good based on IBI and HI scores, and habitat and fish assemblage measures were highly correlated. Stream biotic integrity and habitat quality were negatively correlated with the extent of agriculture and positively correlated with extent of wetlands and forest. Correlations were strongest at the catchment scale (IBI with % area as agriculture, r²=0.50, HI with agriculture, r²=0.76), and tended to become weak and non-significant at local scales. Local riparian vegetation was a weak secondary predictor of stream integrity. In this watershed, regional land use is the primary determinant of stream conditions, able to overwhelm the ability of local site vegetation to support high-quality habitat and biotic communities.     

Thresholds in seascape connectivity: influence of mobility, habitat distribution, and current strength on fish movement

Assessing connectivity of the marine environment is a fundamental challenge for marine conservation and planning, yet conceptual development in habitat connectivity has been based on terrestrial examples rather than marine ecosystems. Here, we explore differences in marine environments that could affect localized movement of marine organisms and demonstrate the importance of incorporating them into seascape models. We link a fish-based cost surface model to simulated seascapes to test hypotheses about the effects of fish mobility, water current strength, and their interactions on functional connectivity of a seascape. Our models predict that sedentary fish should be more sensitive to habitat change than more mobile fish. Furthermore, highly mobile fish should be more sensitive to water currents than habitat change. In our models, the cost of swimming against a current (of any strength) exceeded its benefits, resulting in overall decreases in connectivity with increasing current strengths. We further hypothesized that thresholds in functional connectivity will be affected by both fish mobility and water current strength. Connectivity thresholds in the models occurred when 10–50 % of benthic habitat was favourable; below these thresholds there was a rapid increase in path cost. Thresholds were influenced by the interaction of relative habitat costs (simulated fish mobility) and habitat fragmentation: thresholds for less mobile fish (higher relative cost) were reached at lower habitat abundance when habitat was fragmented, while thresholds for mobile fish were less affected by fragmentation. Our approach suggests mobility and water current are useful indicators of connectivity in marine environments and should be incorporated in seascape models.     

Modeling seasonal dynamics of small fish cohorts in fluctuating freshwater marsh landscapes

Small-bodied fishes constitute an important assemblage in many wetlands. In wetlands that dry periodically except for small permanent waterbodies, these fishes are quick to respond to change and can undergo large fluctuations in numbers and biomasses. An important aspect of landscapes that are mixtures of marsh and permanent waterbodies is that high rates of biomass production occur in the marshes during flooding phases, while the permanent waterbodies serve as refuges for many biotic components during the dry phases. The temporal and spatial dynamics of the small fishes are ecologically important, as these fishes provide a crucial food base for higher trophic levels, such as wading birds. We develop a simple model that is analytically tractable, describing the main processes of the spatio-temporal dynamics of a population of small-bodied fish in a seasonal wetland environment, consisting of marsh and permanent waterbodies. The population expands into newly flooded areas during the wet season and contracts during declining water levels in the dry season. If the marsh dries completely during these times (a drydown), the fish need refuge in permanent waterbodies. At least three new and general conclusions arise from the model: (1) there is an optimal rate at which fish should expand into a newly flooding area to maximize population production; (2) there is also a fluctuation amplitude of water level that maximizes fish production, and (3) there is an upper limit on the number of fish that can reach a permanent waterbody during a drydown, no matter how large the marsh surface area is that drains into the waterbody. Because water levels can be manipulated in many wetlands, it is useful to have an understanding of the role of these fluctuations.     

The distribution of plant species in urban vegetation fragments

(1) The presence and absence of 22 plant species of various growth forms and habitat associations were analysed in 423 habitat fragments totalling 10.4 km² in a 268 km² urban and suburban region, in Birmingham, UK. (2) Multivariate logistic regressions were used to assess the effects of patch geometry and quality on the species distributions. Measures of geometry were area, shape (S-factor), distance from open countryside and various measures of isolation from other patches. Potential habitat for each species was determined quantitatively, and the distribution of each species was considered within a subset of patches containing potentially suitable habitat types. There was found to be a significant positive correlation between the density of patches available to a species and the proportion of these patches which were occupied. (3) Logistic analyses and incidence functions revealed that, for many of the species, occupancy increased with site age, area, habitat number and similarity of adjacent habitats, while increasing distance to the nearest recorded population of the same species decreased the likelihood that a species would be found in a patch. (4) Patterns of occupancy are consistent with increased extinction from small sites, and colonisation of nearby habitats, coupled with an important role for site history. We conclude that spatial dynamics at the scale of the landscape are of importance to the long-term persistence of many plant species in fragmented landscapes, and must be seriously considered in conservation planning and management. These results have direct implications for the siting and connectivity of urban habitat reserves.     

Linking habitat suitability and road mortalities across geographic ranges

Protected areas are established to conserve biodiversity and facilitate resilience to threatening processes. Yet protected areas are not isolated environmental compounds. Many threats breach their borders, including transportation infrastructure. Despite an abundance of roads in many protected areas, the impact of roads on biota within these protected areas is usually unaccounted for in threat mitigation efforts. As landscapes become further developed and the importance of protected areas increases, knowledge of how roads impact on the persistence of species at large scales and whether protected areas provide relief from this process is vital. We took a two-staged approach to analysing landscape-scale habitat use and road-kill impacts of the common wombat (Vombatus ursinus), a large, widely distributed herbivore, within New South Wales (NSW), Australia. Firstly, we modelled their state-wide distribution from atlas records and evaluated the relationship between habitat suitability and wombat road fatalities at that scale. Secondly, we used local-scale fatality data to derive an annual estimate of wombats killed within an optimal habitat area. We then combined these two approaches to derive a measure of total wombats killed on roads within the protected area network. Our results showed that common wombats have a broad distribution (290,981?km²), one quarter (24.9?%) of their distribution lies within protected areas, and the percentage of optimal habitat contained within protected areas is 35.6?%, far greater than the COP10 guidelines of 17?%. Problematically, optimal habitat within protected areas was not a barrier to the effects of road-kill, as we estimated that the total annual count of wombat road-kill in optimal habitat within protected areas could be as high as 13.6?% of the total NSW population. These findings suggest that although protected areas are important spatial refuges for biodiversity, greater effort should be made to evaluate how reserves confer resilience from the impacts of roads across geographic ranges.     

Forest conservation and land development in Puerto Rico

In the Caribbean island of Puerto Rico, rapid land-use changes over the past century have included recent land-cover conversion to urban/built-up lands. Observations of this land development adjacent to reserves or replacing dense forest call into question how the changes relate to forests or reserved lands. Using existing maps, this study first summarizes island-wide land-cover change between 1977-78 and 1991-92. Then, using binomial logit modeling, it seeks evidence that simple forest cover attributes, reserve locations, or existing land cover influence land development locations. Finally, this study quantifies land development, reserve protection and forest cover by ecological zone. Results indicate that 1) pasture is more likely to undergo land development than shrubland plus forest with low canopy density, 2) forest condition and conservation status appear unimportant in that development locations neither distinguish between classes of forest canopy development nor relate to forest patch size or reserve proximity, and 3) most land development occurs in the least-protected ecological zones. Outside the boundaries of strictly protected forest and other reserves, accessibility, proximity to existing urban areas, and perhaps desirable natural settings, serve to increase land development. Over the coming century, opportunities to address ecological zone gaps in the islands forest reserve system could be lost more rapidly in lowland ecological zones, which are relatively unprotected.This revised version was published online in May 2005 with corrections to the Cover Date.     

Living on the edge: quantifying the structure of a fragmented forest landscape in England

Forest ecosystems have been widely fragmented by human land use, inducing significant microclimatic and biological changes at the forest edge. If we are to rigorously assess the ecological impacts of habitat fragmentation, there is a need to effectively quantify the amount of edge habitat within a landscape, and to allow this to be modelled for individual species and processes. Edge effect may extend only a few metres or as far as several kilometres, depending on the species or process in question. Therefore, rather than attempting to quantify the amount of edge habitat by using a fixed, case-specific distance to distinguish between edge and core, the area of habitat within continuously-varying distances from the forest edge is of greater utility. We quantified the degree of fragmentation of forests in England, where forests cover 10 % of the land area. We calculated the distance from within the forest patches to the nearest edge (forest vs. non-forest) and other landscape indices, such as mean patch size, edge density and distance to the nearest neighbour. Of the total forest area, 37 % was within 30 m and 74 % within 100 m of the nearest edge. This highlights that, in fragmented landscapes, the habitats close to the edge form a considerable proportion of the total habitat area. We then show how these edge estimates can be combined with ecological response functions, to allow us to generate biologically meaningful estimates of the impacts of fragmentation at a landscape scale.     

Effects of spatial habitat heterogeneity on habitat selection and annual fecundity for a migratory forest songbird

Understanding how spatial habitat patterns influence abundance and dynamics of animal populations is a primary goal in landscape ecology. We used an information-theoretic approach to investigate the association between habitat patterns at multiple spatial scales and demographic patterns for black-throated blue warblers (Dendroica caerulescens) at 20 study sites in west-central Vermont, USA from 2002 to 2005. Sites were characterized by: (1) territory-scale shrub density, (2) patch-scale shrub density occurring within 25 ha of territories, and (3) landscape-scale habitat patterns occurring within 5 km radius extents of territories. We considered multiple population parameters including abundance, age ratios, and annual fecundity. Territory-scale shrub density was most important for determining abundance and age ratios, but landscape-scale habitat structure strongly influenced reproductive output. Sites with higher territory-scale shrub density had higher abundance, and were more likely to be occupied by older, more experienced individuals compared to sites with lower shrub density. However, annual fecundity was higher on sites located in contiguously forested landscapes where shrub density was lower than the fragmented sites. Further, effects of habitat pattern at one spatial scale depended on habitat conditions at different scales. For example, abundance increased with increasing territory-scale shrub density, but this effect was much stronger in fragmented landscapes than in contiguously forested landscapes. These results suggest that habitat pattern at different spatial scales affect demographic parameters in different ways, and that effects of habitat patterns at one spatial scale depends on habitat conditions at other scales.     

The effect of target extent on the location of optimal protected areas networks in Canada

Various jurisdictions in Canada are currently undertaking, or have recently completed, planning exercises as part of implementation and expansion of representative reserve networks (networks of provincial parks, national parks, ecological reserves, etc.). These exercises have resulted in recommendations to governments about which areas of land should be set aside as protected areas, and different levels of government have been involved in the process of land acquisition. In some cases, planning exercises have included implementation of new protected areas to complement existing reserve networks. Many of these exercises have applied principles such as complementarity, using heuristic algorithms that are well-described in the literature. These planning exercises may be conducted within politically or ecologically bounded target regions of varying extents. Here, I develop candidate locations for representative reserve areas for disturbance-sensitive mammals across Canada. I use ecologically bounded regions (within the national boundaries of Canada) at three different levels of spatial hierarchy: mammal provinces, ecozones, and ecoregions. I show that the extent of the target region has an effect on the minimum number of protected areas required to achieve representation; a larger region requires fewer protected areas than the sum of the protected areas required to represent its component regions at a lower level of spatial hierarchy. The results illustrate that selection of sites for inclusion in a reserve network is highly scale-dependent, and different spatial extents in the target regions may introduce inefficiencies or redundancies in selecting representative protected areas.     

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.     

Impact of land use compactness on the habitat services from green infrastructure in Wuhan,China

As an important carrier of biodiversity, green infrastructure (GI) is significantly affected by changes in urban land use in the process of urbanization. In this study, habitat services from GI were used to represent biodiversity support services, and geographic information system (GIS), remote sensing and statistical analysis were combined to analyze the changes in urban land use compactness and GI habitat services in Wuhan in 2005, 2013 and 2018. Seven indices for land use compactness mainly covering three aspects (land use morphology, land use intensity and land function layout) were selected to explore the correlation and regression relationships between urban land use compactness and habitat services on a grid scale. The results show that: i) The urban land use in Wuhan presents a compact development trend except for the degree of integration; and habitat services decrease along with increasing land use compactness. ii) Relative to land use morphology and land function layout, land use intensity is a more prominent factor affecting habitat services, with construction land density and residential land density always being significant indicators for the habitat pattern. iii) Urban areas with different degrees of land use compactness tend to have different indices that affect the habitat services. Therefore, differential urban development strategies should be formulated based on the regional characteristics of land use compactness levels, so as to coordinate urban compact land use and biodiversity conservation.