Designing marine reserves for interacting species: Insights from theory

The primary goals of marine reserves include protecting biodiversity and ecosystem structure. Therefore, a multispecies approach to designing and monitoring reserve networks is necessary. To gain insight into how the interactions between species in marine communities may affect reserve design, we synthesize marine reserve community models and community models with habitat destruction and fragmentation, and we develop new extensions of existing models. This synthesis highlights the potential for species interactions to alter reserve design criteria; in particular, accounting for species interactions often leads to an increase in reserve size necessary to protect populations. Accounting for species interactions also indicates the need to base reserve design and monitoring on a variety of species, especially long-distance dispersers, inferior colonizers, and specialists. Finally, the new model extensions highlight how, given dispersal, source populations outside reserves as well as increases in fished populations after reserve establishment may negatively affect reserve populations of competitors or prey. Therefore, multispecies harvest dynamics outside reserves and before reserve establishment are critical to determining the appropriate reserve size, spacing, and expectations after establishment. These models highlight the importance of species interactions to reserve design and provide guidelines for how this complexity can begin to be incorporated into conservation planning.     

Conservation in a city: Do the same principles apply to different taxa?

Factors shaping overall species richness and representation of endangered species of vascular flora and butterflies were determined in 48 nature reserves in Prague, Czech Republic. Total species richness of both groups, and the presence of endangered butterflies, reflect the present status of habitats, while that of endangered plants reflects habitat composition at the time of reserve establishment. Reserve area has a much stronger effect on the species richness of sessile plants than mobile butterflies which, especially endangered species, respond more positively to heterogeneity than to area. Both species richness and endangered species peak in reserves half covered with forest, likely because they harbor species of both woodland and non-woodland habitats, and edge specialists. Solely relying on area and disregarding habitat quality, or a failure to conserve small but high quality sites, may be counterproductive for conserving endangered plant and butterfly species. To conserve diversity of plants and butterflies current management practices, often aimed at maintaining large blocks of pre-selected plant communities, should change to include maintenance of fallows, edges and transient zones.     

Marine protected areas export larvae of infauna, but not of bioengineering mussels to adjacent areas

Populations of organisms that create habitat can often be fragmented throughout landscapes by anthropogenic disturbances such as harvesting and loss or change to the identity of such bioengineers may lead to large changes in biodiversity. Using the fauna associated with a bioengineer, the intertidal mussel Perna perna, we tested hypotheses about the relative importance of larval export from protected populations in marine reserves. Harvesting led to the replacement of P. perna and the domination of shores outside reserves by turf-forming coralline algae, mostly Corallina spp. We determined whether the diverse fauna recruiting onto artificial units of habitat placed within mussel beds differed between reserves and non-reserve areas or whether shores outside reserves, and open to harvesting, received recruits through larval export from reserves. Furthermore, we determined whether this was affected by the distance away from reserves and whether colonisation was achieved by movement of adults from surrounding biogenic habitats or via the plankton. Overall, we found no effect of increasing distance away from a reserve on the cover of adult mussels or associated fauna. We found strong effects of the presence of marine reserves on abundances of molluscs and polychaetes but not crustaceans. There were greater densities of molluscs in sites with a reserve (i.e. inside reserves, and up to 5 km outside reserve boundaries), but more polychaetes in exploited sites. For molluscs, this pattern was driven by gastropods rather than bivalves. Furthermore, although reserves had greater cover of adult mussels than non-reserve areas, recruitment of mussels was not greater inside or near to reserves. Our study illustrates the effectiveness of these reserves in protecting stocks of adult mussels, and although there was no evidence that reserves provided export of the larvae of mussels (the target species), they did provide larval export of non-targeted associated species. By protecting a harvested bioengineer and through export of the larvae of its associated fauna, these reserves fulfil some, but not all the conservation aims of a marine protected area.     

Climate change might drive the invasive tree Robinia pseudacacia into nature reserves and endangered habitats

Static networks of nature reserves disregard the dynamics of species ranges in changing environments. In fact, climate warming has been shown to potentially drive endangered species out of reserves. Less attention has been paid to the related problem that a warmer climate may also foster the invasion of alien species into reserve networks. Here, we use niche-based predictive modelling to assess to which extent the Austrian Natura 2000 network and a number of habitat types of conservation value outside this network might be prone to climate warming driven changes in invasion risk by Robinia pseudacacia L., one of the most problematic alien plants in Europe.Results suggest that the area potentially invaded by R. pseudacacia will increase considerably under a warmer climate. Interestingly, invasion risk will grow at a higher than average rate for most of the studied habitat types but less than the national average in Natura 2000 sites. This result points to a potential bias in legal protection towards high mountain areas which largely will remain too cold for R. pseudacacia. In contrast, the selected habitat types are more frequent in montane or lower lying regions, where R. pseudacacia invasion risk will increase most pronouncedly.We conclude that management plans of nature reserves should incorporate global warming driven changes in invasion risk in a more explicit manner. In case of R. pseudacacia, reducing propagule pressure by avoiding purposeful plantation in the neighbourhood of reserves and endangered habitats is a simple but crucial measure to prevent further invasion under a warmer climate.     

Designing the core zone in a biosphere reserve based on suitable habitats: Yancheng Biosphere Reserve and the red crowned crane (Grus japonensis)

Although much research has been undertaken to design nature reserves, there are few practical methods to determine the interior structure of a reserve. A procedure for design of the core zone in reserves is proposed. As a case study, the core zone in Yancheng Biosphere Reserve, People's Republic of China, which was established to preserve the endangered red crowned crane (Grus japonensis) is designed. A statistical habitat model using geographic information system (GIS) is developed to predict crane presence or absence. Based on predicted suitable habitats, the minimum core zone is defined. More suitable habitats can be contained in the designated core zone, and this will be beneficial to the conservation and restoration for crane habitats.     

Small marine reserves can offer long term protection to an endangered fish

The protection of exploited species offered by marine reserves is maximised if individual fish live within the boundaries of the reserve for most of their lives. The direct benefit of this protection, the so called ‘reserve effect’, is the build-up of biomass through an increase in individual numbers and size. This effect can take several years depending on the life history traits of the target species. However, empirical studies on individual fish spatial behaviour at temporal scales long enough to be compatible with that of invoking the reserve effect are still virtually lacking. We studied the inter-annual patterns of habitat use of the dusky grouper (Epinephelusmarginatus), an endangered reef fish predator, using passive acoustic telemetry inside and around a small marine reserve in the Azores, mid-north Atlantic. All 11 individuals resided in the reserve year-round for up to 5 years. During these periods, fish were detected nearly every day and utilised stable core activity areas. Two smaller fish apparently abandoned the area after some time, probably relocating outside the reserve. Our results indicate that even small marine reserves can promote the long-term recovery of some endangered species if the long-term behaviour (i.e. site fidelity) of individuals is appropriate. This result bears direct implications for most existing coastal marine reserves, given that they fall into the small size range and many overexploited reef fish species may be highly site attached.     

The effects of including marine ecological values in terrestrial reserve planning for a forest-nesting seabird

Theoretical advances in systematic reserve design aim to promote the efficient use of limited conservation resources and to increase the likelihood that reserve networks enhance the persistence of valued species and ecosystems. However, these methods have rarely been applied to species that rely on spatially disjunct habitats. We used the marbled murrelet, a seabird that requires old-growth forest in which to nest and high quality marine habitats in which to forage, as a case study to explore methods of incorporating multiple ecological values into single species spatial reserve design. Specifically, we used the cost function in MARXAN to include the ecological value of marine habitats while identifying spatial solutions for terrestrial nesting habitat reserves. Including marine values influenced terrestrial reserve designs most when terrestrial habitat targets were low and little or none of the target was represented in pre-existing protected areas. Our results suggest that including marine values in the planning process will influence marbled murrelet terrestrial reserve designs most where substantial terrestrial nesting habitat still exists, where new reserves are relatively unconstrained by pre-existing reserves, or when conservation resources only allow the protection of a small fraction of available habitat. This paper presents a novel framework for incorporating multiple measures of ecological value in the spatial reserve design process and should be particularly useful for species that rely on multiple habitats during their life cycle.     

Design and management of continental wildlife reserves: Lessons from the everglades

Evidence from the attempt to preserve wading birds in Everglades National Park suggests that application of biogeographic theory to design and management of continental wildlife reserves requires considerations additional to those previously proposed. Shape and areal extent alone are inadequate criteria for reserve design. Unlike islands, continental reserves are not necessarily self-contained ecosystems driven by endogenous processes. The isolation of a continental reserve may lead to a phenomenon of ecosystem degeneration, the extent and rapidity of which depends on the ecological condition of adjacent habitat. Management strategies to preserve maximum species richness are seldom totally acceptable and often inherently unattainable. Conflicts between species management and ecosystem management illustrate the need for instituting an array of management strategies on a regional basis for preservation of both endangered species and ecosystems.     

The conservation value for mammals of reserves in the western Australian wheatbelt

Twenty-three reserves in the Western Australian wheatbelt were examined in an attempt to assess their conservation value for native mammals, excluding bats. Multiple regression analysis on log transformed data showed that 72% of the observed variation in mammal species richness between reserves was accounted for by reserve size. The addition of the other reserve variables examined did not increase significantly this explained variation, although significant correlations existed with most variables. Estimates suggest that a minimum reserve area of about 40,000 ha is required to conserve that part of the regional assemblage of mammals in southern and western Australia likely to persist in the face of moderate disturbances by man and his agencies. Reserves should have large areas of major vegetation formations and maximise the number of regional vegetation associations. Nature reserves as small as 30 ha are valuable sanctuaries for certain species of native mammals.Comparison with mammal faunas isolated on islands by Quaternary glacioeustatic sea-level rise shows that in relation to area, wheatbelt reserves are richer in species, but the slopes of the regressions are similar, particularly for those islands that are little disturbed by man and introduced predators. We suggest that most of the species of mammals surviving in the wheatbelt are suited to existing within patches of vegetation, such as nature reserves, because they are adapted to surviving within the natural archipelago of soil and vegetation types which characterise the wheatbelt and southwestern Western Australia. We suggest that the species of mammals that have become extinct in the wheatbelt are those that are unable to cope with alteration in environmental patchiness caused by changes in the pattern of fires resulting from European occupation.     

Using landscape suitability models to reconcile conservation planning for two key forest predators

Protection of area-limited species is an important component of plans to conserve biodiversity, but the habitat needs of such species can be different and important habitats may not align with existing reserves. We used empirically derived landscape suitability models for the spotted owl and the fisher to evaluate the overlap in habitat suitability for these two old forest-associated predators in an area of northern California affected by the Northwest Forest Plan (NWFP), a bioregional conservation plan. The area includes designated Wilderness areas and new reserves (Late-Successional Reserves, LSRs) established under the NWFP. We used the site selection algorithm MARXAN to identify priority habitat areas for each species, and for both combined, and to compare these areas with reserves. Sites were selected under two constraints, to achieve a threshold proportion of total habitat value and to select new areas equal to the total current area in existing reserves. The rank correlation between predicted value for the two species was low (0.11), because areas of highest predicted habitat value were more widely distributed for the owl. This difference also meant that the sites selected to optimize habitat value were more aggregated for fishers than owls, resulting in greater overlap of owl habitat and current reserves. To capture 25%, 50% and 75% of total habitat value for the owl required 14.0%, 29.2%, and 47.3% of the planning units, respectively; capturing the same for the fisher required only 5.3%, 13.5%, and 27.2%. A combined owl-fisher scenario resulted in areas that overlapped only ∼50% of existing reserves. The current location of LSRs may not be the best solution to maintaining well-connected habitats for these area-limited species in northwestern California. Whether LSRs are a better solution to protecting the diversity of other lesser-known taxa (i.e., salamanders and mollusks) is the subject of related work.     

Local population structure of a naturally occurring metapopulation of the quokka (Setonix brachyurus Macropodidae: Marsupialia)

We investigated the population structure of the quokka (Setonix brachyurus) on the mainland of Western Australia using mark–recapture techniques. Seven previously known local populations and one unconfirmed site supporting the preferred, patchy and discrete, swampy habitat of the quokka were trapped. The quokka is now considered as locally extinct at three sites. The five remaining sites had extremely low numbers, ranging from 1 to 36 individuals. Population density at these sites ranged from 0.07 to 4.3 individuals per hectare. There has been no response to the on-going, 6 year fox control programme occurring in the region despite the quokkas’ high fecundity and this is due to low recruitment levels. The remaining quokka populations in the northern jarrah forest appear to be the terminal remnants of a collapsing metapopulation.     

Methods for reserve selection: Interior point search

Spatial reserve design concerns the planning of biological reserves for conservation. Typical reserve selection formulations operate on a large set of landscape elements, which could be grid cells or irregular sites, and selection algorithms aim to select the set of sites that achieves biodiversity target levels with minimum cost. This study presents a completely different optimization approach to reserve design. The reserve selection problem can be considerably simplified given the reasonable assumptions that: (i) maximum reserve cost is known; (ii) the approximate number of new reserves to be established is known; (iii) individual reserves need to be spatially contiguous. Further assuming the ability to construct a set of reserves in an efficient and close to optimal manner around designated reserve locations, the reserve selection problem can be turned into a search for a single interior point and area for each reserve. The utility of the proposed method is demonstrated for a data set of seven indicator species living in an conservation priority area in Southern Australia consisting of ca 73,000 selection units, with up to 10,000 cells chosen for inclusion in a reserve network. Requirements (ii) and (iii) above make interior point search computationally very efficient, allowing use with landscapes in the order of millions of elements. The method could also be used with non-linear species distribution models.     

Designing a network of marine reserves in the Mediterranean Sea with limited socio-economic data

The present study is the first to determine priorities for the location of marine reserves using spatial prioritization software in the eastern Mediterranean Sea. We used biophysical data from visual census surveys on: fish species abundance, presence of various habitat types, and percent coverage of seagrasses and canopy algae. Efficient conservation planning requires spatially explicit information on how proposed management will affect stakeholders, which in this region was very limited. We created novel socio-economic cost indices to account for fisheries and tourists. Our fishing metrics were based on fisher behaviour including information on the location of ports and areas often inaccessible to fishers due to high wind exposure. We developed a cost index for tourism based on the availability of beds for tourists. We examined how the spatial priorities for marine reserves varied using different combinations of these socio-economic cost metrics. We found about 17% of sites were a high priority regardless of which cost metric was used. We also compared, for the first time in the Mediterranean, our results devised using systematic conservation planning approaches with priorities developed by two non-systematic methods, the Natura 2000 proposed marine reserves and sites that local fishers proposed for protection. Only a few sites identified by our approach were the same as those recommended as part of Natura 2000 or the fishers’ proposals. This suggests that much more work is needed to harmonise existing proposals with the principles of efficient systematic conservation planning.     

The abundance of a threatened arboreal marsupial in relation to anthropogenic disturbances at local and landscape scales in Mediterranean-type forests in south-western Australia

This study investigated associations between the relative abundance of the threatened ngwayir (western ringtail possum, Pseudocheirus occidentalis) and anthropogenic disturbances at local and landscape scales within the publicly-managed jarrah (Eucalyptus marginata) forests of south-western Australia. Logging, fire, fox (Vulpes vulpes) control and forest fragmentation were investigated in relation to the relative abundance of ngwayir at 90 sites within an area of 285,000 ha east of Manjimup; the location of the last remaining substantial population of ngwayir in jarrah forest. Overall, ngwayir abundance was greatest in areas with limited anthropogenic disturbance. At the local-scale, ngwayir abundance was negatively associated with greater fire intensity. At the landscape-scale, it was positively associated with fox control and negatively associated with forest fragmentation and distance from non-remnant vegetation (i.e., agriculture and tree plantations). Abundance was also greatest in predominantly unlogged landscapes and in forests that had been regrowing for an average of 40 years since the landscape was most recently logged, in other words, where logging was historically least intense. Interactions between fox control efforts and forest fragmentation were also important. This study emphasises the importance of conducting research at appropriate spatial scales and to account for the synergistic effects of the causes of decline. An adaptive management approach to the mitigation of the agents of decline is recommended.Indirect evidence indicates that high value habitat for ngwayir has in all likelihood been selectively cleared for agriculture, owing to its fertile and productive nature. Habitat loss is, therefore, also likely to be a major cause of the modern decline of the species. While many jarrah forest areas that support remaining high abundances of the ngwayir have been incorporated into reserves, conservation of ngwayir habitat and populations outside reserves also will be essential for the recovery and long-term viability of the species.     

Historical impacts on linear habitats: The present distribution of grassland species in forest-edge vegetation

In highly fragmented agricultural landscapes, abandoned forests and dense coniferous plantations established on former semi-natural grassland remain potentially suitable sites for the restoration of grassland communities. The roadside vegetation along the edges of these remnant forests could be a key landscape component, because these communities retain pools of grassland species that are maintained by regular mowing alongside public roads to improve traffic safety. We evaluated the effect of land-use history and the proportion of suitable surrounding habitats on the present distribution of grassland species in roadside forest-edge vegetation. The average number of grassland species was significantly lower at sites that had been cultivated since the 1950s, but it did not differ between uncultivated sites and sites cultivated during the 1880s. Positive effects of the proportion of suitable habitats around the sites were detected at specific spatial scales (500- and 700-m squares), and these effects were indistinct at sites that had lost populations to cultivation. In addition to the present habitat conditions (e.g., forest type), the best-fit model for explaining the present distribution of grassland species at a site included both the site’s land-use history and the past proportion of suitable habitat around the sites. Even in remnant linear habitats such as forest-edge vegetation along roads, historical patterns of site conditions and the landscape matrix at optimum scales can provide useful knowledge to improve explanations of the present distributions of grassland species. These information can help identify abandoned or planted forest sites potentially suitable for restoration with grassland species.     

Applying species distribution modelling to identify areas of high conservation value for endangered species: A case study using Margaritifera margaritifera (L.)

The development and implementation of a population supplementation and restoration plan for any endangered species should involve an understanding of the species’ habitat requirements prior to the release of any captive bred individuals. The freshwater pearl mussel, Margaritifera margaritifera, has undergone dramatic declines over the last century and is now globally endangered. In Northern Ireland, the release of captive bred individuals is being used to support wild populations and repatriate the species in areas where it once existed. We employed a combination of maximum entropy modelling (MAXENT) and Generalized Linear Mixed Models (GLMM) to identify ecological parameters necessary to support wild populations using GIS-based landscape scale and ground-truthed habitat scale environmental parameters. The GIS-based landscape scale model suggested that mussel occurrence was associated with altitude and soil characteristics including the carbon, clay, sand, and silt content. Notably, mussels were associated with a relatively narrow band of variance indicating that M. margaritifera has a highly specific landscape niche. The ground-truthed habitat scale model suggested that mussel occurrence was associated with stable consolidated substrates, the extent of bankside trees, presence of indicative macrophyte species and fast flowing water. We propose a three phase conservation strategy for M. margaritifera identifying suitable areas within rivers that (i) have a high conservation value yet needing habitat restoration at a local level, (ii) sites for population supplementation of existing populations and (iii) sites for species reintroduction to rivers where the mussel historically occurred but is now locally extinct. A combined analytical approach including GIS-based landscape scale and ground-truthed habitat scale models provides a robust method by which suitable release sites can be identified for the population supplementation and restoration of an endangered species. Our results will be highly influential in the future management of M. margaritifera in Northern Ireland.     

Modelling nesting habitat as a conservation tool for the Eurasian black vulture (Aegypius monachus) in Dadia Nature Reserve, northeastern Greece

The Eurasian black vulture (Aegypius monachus) is a globally endangered species, vulnerable in Europe and endangered in Greece. We modelled its nesting preferences in Dadia reserve, northeastern Greece using logistic models at multi-scale level combined by Bayesian statistics. Compared with the random sites, the vultures nested at trees with greater diameter (DBH), lower height, and lower total number of trees around the nest tree, steeper slopes and greater distance from forest roads. Our results indicate that conservation and management guidelines for black vultures must aim: (1) to preserve old, isolated mature trees in the reserve, (2) to maintain the zones of strict protection as vulture sanctuary, including most of the suitable nesting habitat, (3) to protect the apparently suitable but still unused habitat in the rest of the reserve from disturbance and logging, (4) to monitor any changes in habitats and use our models to evaluate and predict their effect on vulture nesting in the reserve.     

1990-2017年喀斯特自然保护区土地利用变化对生境质量的影响

[目的] 探讨自然保护区生境质量变化规律及其影响因素,为制定有效的区域生态保护政策提供科学依据。[方法] 基于Landsat系列影像数据,采用生境质量估算模型与土地利用转型生境贡献率,以贵州省兴义市坡岗自然保护区为例,分析土地利用变化对不同功能分区生境质量的影响并定量评估退耕还林还草政策情景对生境质量改善效果。[结果] 1990—2017年自然保护区土地流转主要发生在草地和耕地转为林地、其他类型转为草地和林地间。28 a保护区平均生境质量提高15.71%,且呈现先增加后减少的趋势。1990年保护区平均生境质量表现为：缓冲区 > 核心区 > 试验区,2001年以后转换为：核心区 > 缓冲区 > 试验区。在退耕还林还草政策情景下,坡岗自然保护区平均生境质量从当前情景的0.88提高到0.92,生境质量改善。[结论] 坡岗自然保护区的建立、退耕还林还草工程的实施以及人类活动的增加是影响保护区生境质量变化的主要原因。     

Reserve selection with minimum contiguous area restrictions: An application to open space protection planning in suburban Chicago

Conservation efforts often require site or parcel selection strategies that lead to spatially cohesive reserves. Although habitat contiguity is thought to be conducive to the persistence of many sensitive species, availability of funding and suitable land may restrict the extent to which this spatial attribute can be pursued in land management or conservation. Using optimization modeling, we explore the economic and spatial tradeoffs of retaining or restoring grassland habitat in contiguous patches of various sizes near the Chicago metropolitan area. The underlying mathematical construct is the first exact, generalized formulation that directly models spatial contiguity in optimal reserve selection. The construct allows conservation planners to analyze and weigh different minimum contiguous habitat size requirements that are to be used in specific land acquisition or retention projects.     

Evaluating population persistence of Delmarva fox squirrels and potential impacts of climate change

In addition to the combined effects of forest fragmentation, habitat loss, and population isolation on the long-term persistence of many species including the endangered Delmarva fox squirrel (Sciurus niger cinereus), future changes in climate may make existing habitats less productive and more variable. The Palmer Drought Severity Index (PDSI) for the Delmarva Peninsula of the mid-Atlantic USA, reveals a trend for longer durations of potentially unfavorable conditions for fox squirrel population growth. We used a stochastic population matrix model and available life history information to assess population extinction risk for the Delmarva fox squirrel under a number of scenarios of landscape change and environmental variation, including uncertainties in the future range of climate patterns. Patch size (carrying capacity) was the most important factor influencing persistence of isolated populations. Extinction risk increased markedly across all patch sizes when year to year patterns in environmental variability were autocorrelated to match regional patterns in the PDSI. Increased autocorrelation matching the regional PSDI increased extinction risk, ranging from a factor of 5 to a factor of over 100 in some scenarios when compared to uncorrelated patterns in environmental variability. Increasing the range of variation in survival probabilities was less important to persistence, but its effect also increased when year-to-year changes were autocorrelated in time. Comparing model results with the size and landscape configuration of currently occupied patches on the Delmarva Peninsula showed that many existing populations are above the size threshold identified by these simulations for long-term persistence under current conditions, but these may become vulnerable should climate variability increase and adverse conditions persist for several years at a time.