Conservation value of small reserves

Microreserves are an important tool for amphibian conservation

Initiatives to protect 30% of Earth by 2030 prompt evaluation of how to efficiently target shortcomings in the global protected area (PA) network. Focusing on amphibians, the most vulnerable vertebrate class, we illustrate the conservation value of microreserves, a term we employ here to refer to reserves of <10 km2. We report that the network continues to under-represent threatened amphibians and that, despite this clear shortcoming in land-based conservation, the creation of PAs protecting amphibians slowed after 2010. By proving something previously assumed-that amphibians generally have smaller ranges than other terrestrial vertebrates-we demonstrate that microreserves could protect a substantial portion of many amphibian ranges, particularly threatened species. We find existing microreserves are capable of hosting an amphibian species richness similar to PAs 1000-10,00X larger, and we show that amphibians' high beta diversity means that microreserves added to a growing PA network cover amphibian species 1.5-6x faster than larger size categories. We propose that stemming global biodiversity loss requires that we seriously consider the conservation potential of microreserves, using them to capture small-range endemics that may otherwise be omitted from the PA network entirely.

Overcoming confusion and stigma in habitat fragmentation research

Anthropogenic habitat loss is widely recognized as a primary environmental concern. By contrast, debates on the effects of habitat fragmentation persist. To facilitate overcoming these debates, here we: (i) review the state of the literature on habitat fragmentation, finding widespread confusion and stigma; (ii) identify consequences of this for biodiversity conservation and ecosystem management; and (iii) suggest ways in which research can move forward to resolve these problems. Confusion is evident from the 25 most-cited fragmentation articles published between 2017 and 2021. These articles use five distinct concepts of habitat fragmentation, only one of which clearly distinguishes habitat fragmentation from habitat area and other factors ('fragmentation per se'). Stigmatization is evident from our new findings that fragmentation papers are more charged with negative sentiments when compared to papers from other subfields in the environmental sciences, and that fragmentation papers with more negative sentiments are cited more. While most empirical studies of habitat fragmentation per se find neutral or positive effects on species and biodiversity outcomes, which implies that small habitat patches have a high cumulative value, confusion and stigma in reporting and discussing such results have led to suboptimal habitat protection policy. For example, government agencies, conservation organizations, and land trusts impose minimum habitat patch sizes on habitat protection. Given the high cumulative value of small patches, such policies mean that many opportunities for conservation are being missed. Our review highlights the importance of reducing confusion and stigma in habitat fragmentation research. To this end, we propose implementing study designs in which multiple sample landscapes are selected across independent gradients of habitat amount and fragmentation, measured as patch density. We show that such designs are possible for forest habitat across Earth's biomes. As such study designs are adopted, and as language becomes more precise, we expect that confusion and stigma in habitat fragmentation research will dissipate. We also expect important breakthroughs in understanding the situations where effects of habitat fragmentation per se are neutral, positive, or negative, and the reasons for these differences. Ultimately this will improve efficacy of area-based conservation policies, to the benefit of biodiversity and people.

Proximity among protected area networks promotes functional connectivity for wintering waterfowl

The equilibrium theorem provided a fundamental framework for understanding species' distributions and movement in fragmented ecosystems. Wetland-dependent avian species are model organisms to test insular predictions within protected area networks because their mobility allows surveillance of isolated patches without landscape barriers. We hypothesized size and isolation would influence functional connectivity of sanctuaries by GPS-marked wintering mallards (Anas platyrhynchos) within a mesocosm protected sanctuary area network. We evaluated functional connectivity and sanctuary use, measured by movements between sanctuaries, using a multistate modeling framework. Proximity drove connectivity, underscoring that patch isolation-not size-influenced connectivity, even for an avian species with no ascertainable landscape resistance or barriers. We also found that sanctuary use increased overwintering survival by reducing harvest mortality. Our test of equilibrium theory predictions demonstrated that isolation of protected sanctuary areas supersedes their size in determining functional connectivity for mallards and access to these areas may have direct fitness consequences. Our findings could refine land acquisition, restoration, and management practices with equal or greater emphasis on adjacency in protected area network design, especially for wetland-dependent migratory gamebirds.

Ten key issues for ecological restoration of territorial space

This study innovatively puts forward the three-stage restoration goals and cutting-edge key scientific issues of ecological restoration, as well as their relationships.

Management of a Globally Imperiled and Fire-Dependent Ecosystem in the Urban Matrix of Miami–Dade County, Florida: A Case Study of the Richmond Tract Pine Rocklands

Pine rockland habitat of South Florida is among the most highly threatened terrestrial ecosystems in the neo-subtropics and is among the rarest worldwide. With only 1.2% of its original extent remaining outside Everglades National Park, fewer than 780 hectares of this ecosystem remains across all of South Florida. This fire-dependent ecosystem—habitat for many rare, endemic species—has experienced substantial deforestation and defaunation due to urbanization, land use change, habitat fragmentation, fire suppression, and exotic plant invasions. Owing to the small size of remaining fragments, and the fact that most are surrounded by urbanization, adequate burning regimes are suppressed. The Richmond Tract, a complex of twelve separate parcels under multiple private and public ownership partially surrounding Zoo Miami, is the largest tract of pine rockland outside the federal protection of Everglades National Park. In this article, we take inventory of the threatened biodiversity at the Richmond Tract and focus on the policy and management landscape. We take a close look at threats to the pine rockland’s persistence here and review approaches that either help maintain the health of this ecosystem or those that may need to be reconsidered. We end by discussing coordination among multiple stakeholder groups, the potential use for incentive-based conservation practices, and suggesting ways to improve management in highly urbanized South Florida.

A framework for identifying bird conservation priority areas in croplands at national level

Global biodiversity is declining at an unprecedented rate, and the Post-2020 Global Biodiversity Framework requires each country to fulfill the conservation targets in biodiversity-inclusive spatial planning. Croplands provide habitat and food for many species, making them crucial for biodiversity conservation in addition to food production. Assessing conservation priorities in cropland is a prerequisite to allocate conservation resources and plan actions for better conservation outcomes. Yet quantitative methods to assess cropland conservation priority for biodiversity conservation at a national scale are still lacking. We proposed a framework for identifying the conservation priority in cropland for bird species at a national scale and applied the framework in China. We calculated the suitable habitat for each species and used a complementarity-based approach to designate the irreplaceable conservation priority areas considering richness, threatened level, and conservation percentage targets. We identified cropland taking up 6.76% of China's land area as a bird conservation priority, partially covering the suitable habitat of all the study species. By analyzing the landscape pattern of the priority areas and species' foraging traits, we provided policy-making suggestions according to area-specific characteristics. This framework can be used to identify priority areas for large-scale biodiversity conservation for different countries.

Invasive catfish in northern Italy and their impacts on waterbirds

Predatory fish have occasionally been observed preying on birds, sometimes repeatedly, but few studies were able to unravel the overall significance of avian prey in fish diet and the predation impacts on bird populations. We used a control/impact study setup, using a Nature Reserve in northern Italy and a nearby control area, to determine: 1) the contribution of waterbirds to wels catfish diet in the Reserve, 2) the population density of wels catfish in the Reserve and control area and 3) the potential impacts of waterbird depredation by wels catfish on waterbird population trends. Our stable isotope Bayesian mixing model indicated that birds contributed 12.2% (5–27.9%, 50% confidence interval) of the diet of large wels catfish (&gt; 98 cm in total length). Large individuals constituted the majority of the population in the shoreline areas of the reserve in 2013–2019, where the population was stable despite control efforts. Numbers were below detectable levels in the control area. Large wels catfish consumed an average of 224, 148 and 187 kg of birds during the 2019 chick growing period, as estimated through three different bioenergetic models. Compared to the control area, mallard reproductive success was diminished in the Reserve, likely due to higher rates of fish predation, although effects were variable in different years. Overall, our data suggest that high densities of invasive wels catfish might impact waterbird reproductive success through predation on bird chicks, but further studies would be needed to reduce uncertainties related to the intrinsic variability of field ecology data. Our study constitutes a preliminary attempt to assess the potential of introduced wels catfish to affect the conservation value of waterbird protection areas, and should be repeated at broader spatial and temporal scales.

Multiple Anthropogenic Pressures Lead to Seed Dispersal Collapse of the Southernmost Palm Jubaea chilensis

Seed dispersal is a critical process for plant reproduction and regeneration. Successful recruitment depends on pre- and post-dispersal processes that complete a seed’s journey until becoming a new plant. However, anthropogenic stressors may disrupt the seed dispersal process at some stages, collapsing plant regeneration and hampering its long-term persistence. The Chilean palm tree Jubaea chilensis is the southernmost and the only non-tropical palm species, which currently relies on the scatter-hoarding rodent Octodon degus for seed dispersal. We assessed seed fate by measuring predation and dispersal rates through experimental fieldwork in the Palmar de Ocoa site (located within La Campana National Park) and the Palmar El Salto. We also used previous reports on seed harvest and seedling herbivory to depict the whole J. chilensis seed dispersal process and assess the relative importance of different anthropogenic pressures. We asked the following questions: (1) What is the effect of human harvesting on J. chilensis recruitment? (2) Do native and exotic rodents predate J. chilensis seeds in the same way? and (3) Does post-dispersal herbivory matter? We found that J. chilensis fruits are harvested for human consumption, reducing pre-dispersal available seeds by removing about 23 tons per season. Then, post-dispersal seeds at the Ocoa palm grove are heavily predated by exotic (Rattus rattus) and native (Octodon spp.) rodents; only 8.7% of the seeds are effectively dispersed by Octodon degus. At Palmar El Salto, 100% of the seeds were predated by Rattus rattus, precluding further analysis. Finally, 70% of the seedlings were consumed by exotic herbivores (mainly rabbits), resulting in a success rate of 1.81%. Only 7.9% of the surviving seedlings become infantile plants (4 year-old). Our assessment suggests that J. chilensis has aging populations with very few young individuals in disturbed sites to replace the old ones. For those reasons, we suggest increasing its conservation category to critically endangered as land-use change is rapidly fragmenting and shrinking the extant J. chilensis populations. We urge to take urgent actions to protect this relict palm, which otherwise may go extinct in the next decades.

Success in conserving the bird diversity in tropical forests through private protected areas in Western Ecuador

Private protected areas have recently attained more importance at a worldwide level as regards nature conservation. Particularly, the specific region of Western Ecuador receives hardly any protection from the State, and private reserves could, therefore, be a suitable tool to ensure the preservation of its forests and their associated wildlife biodiversity. In this work, we compare the bird species richness between private reserves and public protected areas (managed by the State) located in this region. We also show a checklist of bird species found in the Buenaventura Reserve, a private reserve located in south-western Ecuador. Our comparison shows that smaller private reserves may harbour a similar number of bird species than larger protected areas managed by the state, and they have a higher number of bird species per area. In particular, a total of 233 different bird species were registered in Buenaventura, which were distributed in 16 orders and 42 families. Three species were classified as endangered at an international level: El Oro Parakeet (Pyrrhura orcesi), El Oro Tapaculo (Scytalopus robbinsi), and the Grey-backed Hawk (Pseudastur occidentalis), and another three at a national level: the Long-wattled Umbrellabird (Cephalopterus penduliger), the Slaty-winged Foliage-gleaner (Philydor fuscipenne), and the White-vented Plumeleteer (Chalybura buffonii). Therefore, private reserves can be appreciated as a suitable conservation tool for bird conservation, and they should not be undervalued because of their smaller size. Buenaventura Reserve is a good example of how private reserves are extremely important in fragmented landscapes, as is the case with tropical forests in Western Ecuador.

Comparison between terrestrial mammals in evergreen forests and in seasonal dry forests in Western Ecuador: should efforts be focused on dry forests?

The Coast Region of Ecuador has been dramatically deforested, and most of the remaining natural vegetation is formed of fragmented patches, in which there is little knowledge of wild mammal populations. The objective of this study was to assess the presence and detection rate (DR) of medium and large-size mammals by using camera-traps in fragmented forests located outside the protected areas comparing the two main types of forest: seasonal dry and evergreen. We registered 18 different species, of which four had greater DRs in dry forests (Lycalopex sechurae, Odocoileus peruvianus, Simosciurus stramineus and Sylvilagus daulensis), four were more detected in evergreen forests (Cuniculus paca, Dasyprocta punctata, Dasypus novemcinctus and Procyon cancrivorus), and the remaining 10 species had no significant habitat preference. The mean species richness was similar in both ecosystems, but the number of detections was greater in the evergreen forests. Finally, two of the region’s four threatened species had higher DRs in dry forests. These results suggest that it is necessary to conserve both types of ecosystems to ensure the conservation of all mammals’ species. However, since dry forests are less protected and their threatened fauna suggests that conservation efforts should be particularly focused on them.

Ant Communities Resist Even in Small and Isolated Gypsum Habitat Remnants in a Mediterranean Agroecosystem

Natural and seminatural habitat remnants play a crucial ecological role in intensified agroecosystems. Assumptions on the conservation value of small and poorly connected fragments in a hostile matrix come from generalization obtained from a limited number of taxa, mostly plants, and vertebrates. To date, few studies have analyzed the effect of fragmentation on ant communities in Mediterranean agroecosystems, despite the importance of this group of animals on several key ecosystem functions and services. Here, we analyze the effects of fragment area and connectivity on ant communities in gypsum outcrops in a large cereal agroecosystem of Central Spain. Ant communities were described by their species composition, abundance (total number of occurrences), and number of species, standardized both by area (species density), and abundance (species richness). Observed number of species was relatively high in comparison with other studies in the Mediterranean, and we found no effects of fragment characteristics on species density, species richness and species composition, which implies that even small and isolated patches do have a value for ant conservation. Moreover, total number of occurrences were higher for smaller and more isolated fragments. This finding contrasts with the results reported for other taxa in similar gypsum habitats and suggests that certain ant traits and strategies make them particularly resistant to fragmentation and capable to take advantage of small habitat patches. Given the important ecological role played by ants, we recommend the preservation of these small habitat fragments in the management plans of agroecosystems in these drylands, especially in those cases in which intensification of agricultural practices greatly diminish natural habitat availability.

Small habitat matrix: How does it work?

We present herein our perspective of a novel Small Habitats Matrix (SHM) concept showing how small habitats on private lands are untapped but can be valuable for mitigating ecological degradation. Grounded by the realities in Sabah, Malaysian Borneo, we model a discontinuous "stepping stones" linkage that includes both terrestrial and aquatic habitats to illustrate exactly how the SHM can be deployed. Taken together, the SHM is expected to optimize the meta-population vitality in monoculture landscapes for aerial, arboreal, terrestrial and aquatic wildlife communities. We also provide the tangible cost estimates and discuss how such a concept is both economically affordable and plausible to complement global conservation initiatives. By proposing a practical approach to conservation in the rapidly developing tropics, we present a perspective from "ground zero" that reaches out to fellow scientists, funders, activists and pro-environmental land owners who often ask, "What more can we do?"

Area-based conservation in the twenty-first century

Humanity will soon define a new era for nature-one that seeks to transform decades of underwhelming responses to the global biodiversity crisis. Area-based conservation efforts, which include both protected areas and other effective area-based conservation measures, are likely to extend and diversify. However, persistent shortfalls in ecological representation and management effectiveness diminish the potential role of area-based conservation in stemming biodiversity loss. Here we show how the expansion of protected areas by national governments since 2010 has had limited success in increasing the coverage across different elements of biodiversity (ecoregions, 12,056 threatened species, 'Key Biodiversity Areas' and wilderness areas) and ecosystem services (productive fisheries, and carbon services on land and sea). To be more successful after 2020, area-based conservation must contribute more effectively to meeting global biodiversity goals-ranging from preventing extinctions to retaining the most-intact ecosystems-and must better collaborate with the many Indigenous peoples, community groups and private initiatives that are central to the successful conservation of biodiversity. The long-term success of area-based conservation requires parties to the Convention on Biological Diversity to secure adequate financing, plan for climate change and make biodiversity conservation a far stronger part of land, water and sea management policies.

Critical patch size reduction by heterogeneous diffusion

Population survival depends on a large set of factors and on how they are distributed in space. Due to landscape heterogeneity, species can occupy particular regions that provide the ideal scenario for development, working as a refuge from harmful environmental conditions. Survival occurs if population growth overcomes the losses caused by adventurous individuals that cross the patch edge. In this work, we consider a single species dynamics in a patch with a space-dependent diffusion coefficient. We show analytically, within the Stratonovich framework, that heterogeneous diffusion reduces the minimal patch size for population survival when contrasted with the homogeneous case with the same average diffusivity. Furthermore, this result is robust regardless of the particular choice of the diffusion coefficient profile. We also discuss how this picture changes beyond the Stratonovich framework. Particularly, the Itô case, which is nonanticipative, can promote the opposite effect, while Hänggi-Klimontovich interpretation reinforces the reduction effect.

Designing optimal human-modified landscapes for forest biodiversity conservation

Agriculture and development transform forest ecosystems to human-modified landscapes. Decades of research in ecology have generated myriad concepts for the appropriate management of these landscapes. Yet, these concepts are often contradictory and apply at different spatial scales, making the design of biodiversity-friendly landscapes challenging. Here, we combine concepts with empirical support to design optimal landscape scenarios for forest-dwelling species. The supported concepts indicate that appropriately sized landscapes should contain ≥ 40% forest cover, although higher percentages are likely needed in the tropics. Forest cover should be configured with c. 10% in a very large forest patch, and the remaining 30% in many evenly dispersed smaller patches and semi-natural treed elements (e.g. vegetation corridors). Importantly, the patches should be embedded in a high-quality matrix. The proposed landscape scenarios represent an optimal compromise between delivery of goods and services to humans and preserving most forest wildlife, and can therefore guide forest preservation and restoration strategies.

Reasons for the Survival of Tropical Forest Fragments in Xishuangbanna, Southwest China

Research Highlights: The reasons for persistence of forest fragments in human-dominated landscapes have rarely been examined, despite their importance in biodiversity and ecosystem services. We determined these reasons for forest fragments on collective land in Xishuangbanna prefecture, southwest China. Background and Objectives: Reconciling economic development with biodiversity conservation has been a major challenge in China’s small tropical land area, where local realities have often been in conflict with national policies. In Xishuangbanna, much of China’s most biodiverse forest area has been replaced by cash crops in recent decades, but numerous small forest fragments remain on collective land. Our objective was to find out why these fragments have not been cleared. Methods: We used a combination of semi-structured interviews with 600 households in 69 villages representing nine ethnic groups and information from key informants. Results: Overall, 64% of individual households retained forest fragments on the land allocated to them, and 93% of villages retained larger areas managed as a collective forest. Most (71%) interviewees said that fragments on their own land were on sites of low agricultural value and were retained as fuelwood sources. They were also often (33%) underplanted with crops and supplied other forest products. All interviewees attributed the retention of collective forests to policy restrictions on clearance, with most (96%) mentioning cultural and religious uses and many recognizing environmental benefits. Most were also used as sources of wild edible plants (61%) and other forest products. Many said these collective forests had shrunk over time, particularly in areas suitable for profitable cultivation. Conclusions: China’s new ecological redline policy will protect most larger patches of forest in Xishuangbanna, but the smaller fragments on land allocated to individual households are also of conservation value, particularly in areas with no other forest. Some form of compensation scheme is needed to encourage their continued retention.

Plant–frugivore interactions in an urban nature reserve and its nearby gardens

In the current global context of growing urbanization, urban nature reserves play a crucial role as habitats that serve educational, recreational and conservation purposes. Biodiversity conservation within urban reserves is a challenging task, particularly since connectivity between a reserve and its surrounding artificial green spaces (e.g. gardens and parks) may affect the ecological processes within the reserve in complex ways. In this context, we studied the feeding interactions between plants and birds to provide evidence that an urban nature reserve is connected to its surrounding artificial habitats by mobile organisms. We focused on fleshy-fruited plants and frugivorous birds, and we used a network approach to describe the feeding interactions between these two guilds. The most important connecting bird was Turdus rufiventris, an abundant and obligate frugivore, whose abundance was positively linked to fruit availability in most of the study sites. The apparent increase in the abundance of T. rufiventris in one habitat when it decreases in the other suggests that the two habitats may be complementary for this species. The nature reserve, with many native plants, however, seems to be the preferred site when both habitats offer an abundant fruit supply. Our results suggest changes in either habitat can have consequences in the other one, which has broad implications for the design of management plans of urban nature reserves.