Earth and field observations underpin metapopulation dynamics in complex landscapes: Near-term study on carabids.

Understanding risks to biodiversity requires predictions of the spatial distribution of species adapting to changing ecosystems and, to that end, Earth observations integrating field surveys prove essential as they provide key numbers for assessing landscape-wide biodiversity scenarios. Here, we develop, and apply to a relevant case study, a method suited to merge Earth/field observations with spatially explicit stochastic metapopulation models to study the near-term ecological dynamics of target species in complex terrains. Our framework incorporates the use of species distribution models for a reasoned estimation of the initial presence of the target species and accounts for imperfect and incomplete detection of the species presence in the study area. It also uses a metapopulation fitness function derived from Earth observation data subsuming the ecological niche of the target species. This framework is applied to contrast occupancy of two species of carabids (Pterostichus flavofemoratus, Carabus depressus) observed in the context of a large ecological monitoring program carried out within the Gran Paradiso National Park (GPNP, Italy). Results suggest that the proposed framework may indeed exploit the hallmarks of spatially explicit ecological approaches and of remote Earth observations. The model reproduces well the observed in situ data. Moreover, it projects in the near term the two species' presence both in space and in time, highlighting the features of the metapopulation dynamics of colonization and extinction, and their expected trends within verifiable timeframes.

Metapopulation persistence can be inferred from incomplete surveys.

Habitat destruction and fragmentation are principal causes of species loss. While a local population might go extinct, a metapopulation-populations inhabiting habitat patches connected by dispersal-can persist regionally by recolonizing empty patches. To assess metapopulation persistence, two widely adopted indicators in conservation management are metapopulation capacity and patch importance. However, we face a fundamental limitation in that assessing metapopulation persistence requires that we survey or sample all the patches in a landscape: often these surveys are logistically challenging to conduct and repeat, which raises the question whether we can learn enough about the metapopulation persistence from an incomplete survey. Here, we provide a robust statistical approach to infer metapopulation capacity and patch importance by sampling a portion of all patches. We provided analytic arguments on why the metapopulation capacity and patch importance can be well predicted from sub-samples of habitat patches. Full-factorial simulations with more complex models corroborate our analytic predictions. We applied our model to an empirical metapopulation of mangrove hummingbirds (Amazilia boucardi). On the basis of our statistical framework, we provide some sampling suggestion for monitoring metapopulation persistence. Our approach allows for rapid and effective inference of metapopulation persistence from incomplete patch surveys.

Human-modified landscapes alter mammal resource and habitat use and trophic structure.

The broad negative consequences of habitat degradation on biodiversity have been studied, but the complex effects of natural-agricultural landscape matrices remain poorly understood. Here we used stable carbon and nitrogen isotopes to detect changes in mammal resource and habitat use and trophic structure between preserved areas and human-modified landscapes (HMLs) in a biodiversity hot spot in South America. We classified mammals into trophic guilds and compared resource use (in terms of C3- and C4-derived carbon), isotopic niches, and trophic structure across the 2 systems. In HMLs, approximately one-third of individuals fed exclusively on items from the agricultural matrix (C4), while in preserved areas, ∼68% depended on forest remnant resources (C3). Herbivores, omnivores, and carnivores were the guilds that most incorporated C4 carbon in HMLs. Frugivores maintained the same resource use between systems (C3 resources), while insectivores showed no significant difference. All guilds in HMLs except insectivores presented larger isotopic niches than those in preserved areas. We observed a complex trophic structure in preserved areas, with increasing δ15N values from herbivores to insectivores and carnivores, differing from that in HMLs. This difference is partially explained by species loss and turnover and mainly by the behavioral plasticity of resilient species that use nitrogen-enriched food items. We concluded that the landscape cannot be seen as a habitat/nonhabitat dichotomy because the agricultural landscape matrix in HMLs provides mammal habitat and opportunities for food acquisition. Thus, favorable management of the agricultural matrix and slowing the conversion of forests to agriculture are important for conservation in this region.

Conservation value of small reserves.

The importance of large reserves has been long maintained in the scientific literature, often leading to dismissal of the conservation potential of small reserves. However, over half the global protected-area inventory is composed of protected areas that are <100 ha, and the median size of added protected area is decreasing. Studies of the conservation value of small reserves and fragments of natural area are relatively uncommon in the literature. We reviewed SCOPUS and WOK for studies on small reserve and fragment contributions to biodiversity conservation and ecosystem services, and fifty-eight taxon-specific studies were included in the review. Small reserves harbored substantial portions (upward of 50%) of regional species diversity for many taxa (birds, plants, amphibians, and small mammals) and even some endemic, specialist bird species. Unfortunately, small reserves and fragments almost always harbored more generalist and exotic species than large reserves. Community composition depended on habitat quality, surrounding land use (agricultural vs. urban), and reserve and fragment size, which presents opportunities for management and improvement. Small reserves also provided ecosystem services, such as pollination and biological pest control, and cultural services, such as recreation and improved human health. Limitations associated with small reserves, such as extinction debt and support of area-sensitive species, necessitate a complement of larger reserves. However, we argue that small reserves can make viable and significant contributions to conservation goals directly as habitat and indirectly by increasing landscape connectivity and quality to the benefit of large reserves. To effectively conserve biodiversity for future generations in landscapes fragmented by human development, small reserves and fragments must be included in conservation planning.

Valor de Conservación de las Pequeñas Reservas Resumen La importancia de las reservas muy extensas se ha mantenido durante mucho tiempo dentro de la literatura científica, lo que comúnmente lleva a la desestimación del potencial de conservación de las reservas pequeñas. Sin embargo, más de la mitad del inventario mundial de áreas protegidas está compuesto por zonas resguardadas con un tamaño menor a las 100 ha, y el tamaño promedio de área protegida añadida está disminuyendo. Los estudios sobre el valor de conservación de las reservas pequeñas y los fragmentos de área natural son relativamente poco comunes en la literatura. Revisamos estudios sobre las contribuciones de las reservas pequeñas y los fragmentos a la conservación de la biodiversidad y los servicios ambientales en SCOPUS y en WOK. Se incluyeron 58 estudios específicos de taxón en la revisión. Las reservas pequeñas albergaron porciones sustanciales (más del 50%) de diversidad de especies regionales para muchos taxones e incluso algunas especies de aves endémicas y especialistas. Desafortunadamente, las reservas pequeñas y los fragmentos casi siempre albergaron más especies exóticas y generalistas que las reservas grandes. La composición de la comunidad dependió de la calidad del hábitat, el uso de suelo (urbano versus agrícola) adyacente y el tamaño de la reserva o el fragmento, lo que presenta oportunidades de manejo y mejora. Las reservas pequeñas también proporcionaron servicios ambientales, como la polinización y el control biológico de plagas, y servicios culturales, como la recreación y una mejor salud humana. Las limitaciones asociadas con las reservas pequeñas, como la deuda de extinción y el respaldo a especies sensibles al área, requieren de un complemento de reservas más grandes. Sin embargo, argumentamos que las reservas pequeñas pueden tener contribuciones viables y significativas para las metas de conservación directamente como hábitat e indirectamente con el incremento de la conectividad y la calidad de paisajes para el beneficio de las reservas más grandes. Para conservar efectivamente a la biodiversidad para generaciones futuras en paisajes fragmentados por el desarrollo humano, se debe incluir a las reservas pequeñas y a los fragmentos en la planeación de la conservación.

Well-managed grassland heterogeneity promotes butterfly conservation in a corridor network.

Habitat degradation is a major concern in transformed landscapes, as it reduces complexity by removing species, interactions, and ultimately biodiversity. Degradation is also of concern for ecological networks (ENs) composed of an interconnected system of conservation corridors among South Africa's commercial forestry compartments. These corridors are predominantly grasslands, and used as rangeland, so managed to optimize grazing conditions. Yet, how this management approach influences biodiversity remains unknown. Here, we studied how butterfly assemblages respond to local differences in rangeland quality (low, high and reference sites), and how this effect compared to that of local environmental variables (e.g. rockiness and bare ground), meso environmental gradients (e.g. topographic position and aspect), and landscape composition (i.e. proportion of different land cover types in the surrounding matrix). We calculated species richness and composition, Shannon's diversity index (H'), and the Butterfly Conservation Index (BCIn) representing the proportion of sensitive and range-restricted butterfly species per site. Rangeland quality was considered less important for butterflies than other environmental variables, but it was also significantly confounded with other environmental variables. At the landscape scale, proportion of grassland in the landscape matrix influenced butterfly assemblage composition, while proportion of thicket had a significant positive effect on BCIn. Moreover, the effect of elevation on assemblage composition emphasizes the value of maintaining environmental gradients within these conservation corridors. At the meso spatial scale, butterfly species richness and diversity (H') declined with increased dominance by a single plant species, which usually occurs late in a normal fire cycle. This suggests a reliance by butterflies on recurring natural disturbances for long-term persistence. We recommend moderate patch burning and grazing, as well as occasional hot burns to reduce thicket in Afromontane grassland. This approach would improve local scale vegetation patterns, and increase heterogeneity across the landscape for conserving these butterflies into the future.

Crop landscapes reduced taxonomic and functional richness but increased evenness of aquatic macroinvertebrates in subtropical rivers.

Human activities altering ecosystems structure and function worldwide strongly affect rivers. We studied aquatic macroinvertebrate communities (taxonomic and functional diversity) from rivers immersed in a forest matrix and rivers flowing through croplands. As rivers of the region experience a monsoon climate, high and low water seasons were also considered and their effect tested. We expected lower taxonomic and functional diversity in rivers flowing through croplands, and also during high water periods. We selected five Piedmont forest and three sugarcane crop rivers in Austral Yungas piedmont forests (Argentina), where marginal vegetation, land use, and hydromorphological variables were studied. Samplings were performed in these 8 sites during high and low water seasons of three consecutive years, totaling 32 samples. We analyzed differences between categories through nonparametric analyses of variance and SIMPER analysis. We studied taxonomic diversity through effective number of species and functional diversity using feeding groups with a factorial ANOVA. We calculated different biotic indices to test differences in water quality. We identified 11,034 specimens from 58 families of aquatic macroinvertebrates. Piedmont forest rivers showed higher richness (order 0) than crop rivers, but diversities of orders 1 and 2 showed the opposite pattern. Functional feeding groups were different between both situations. Season greatly influenced the assemblages, with reduced diversity and abundances during high water periods. Biotic indices showed good water quality, except during high water season for crop sites. A complex response of aquatic communities was found, but generally crop sites were more markedly affected during high water season.

Differential matrix use by Neotropical birds based on species traits and landscape condition.

There is considerable uncertainty about the role of human-modified habitats in supporting species in fragmented landscapes. This is because few studies sample outside of native habitats in the "matrix." Those that do, often fail to sample landscapes in a way that accounts for the confounding effects of native habitat pattern and species detection biases that can obscure species responses. We employed multi-species hierarchical occupancy models to determine the use of human-modified habitats by Neotropical birds in landscapes that were similar in forest amount and configuration but surrounded by a matrix of agriculture (predominately pasture), bauxite mining (surface mining for aluminum), or suburban development in central Jamaica. We found that the vast majority of bird species used the matrix: with the highest mean occurrences for open-associated, followed by generalist, and last forest-associated species. Migrant species had higher mean occurrences in all matrix types relative to resident species. Contrary to our expectation, mean occurrence for the entire species community, and for forest-associated and migrant species, were highest in bauxite, intermediate in suburban, and lowest in agriculture. Open-associated species had higher occurrences in both bauxite and agricultural matrices, whereas generalist species had higher occurrences in suburban matrices. Additional behavioral observations indicated that Neotropical birds used matrix areas, particularly scattered trees, to acquire food, and secondarily, as movement conduits. Matrix use patterns reflected the differential availability of potential resources and structural connectivity across the three landscape types, but only for those species adapted to open/edge environments and with generalized habitat requirements. Patterns of matrix use by forest specialists reflected the differential levels of degradation of the native forest; thus, we propose that higher matrix use for forest-dependent species may be induced by diminished within-forest resources. These results underscore that effective management of human-modified matrices requires in-depth understanding of the trade-offs between the benefits available in the matrix and the impacts on the disturbance of native habitats.

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Invasive process of alien species is affected by not only the invaded habitats, but also the surrounding landscape matrix. Understanding the effects of landscape matrix on alien species is of great significance for controlling invasive alien species. We surveyed plant communities along the water-level fluctuating zone (WLFZ) of the Three Gorges Reservoir. Invasive status of alien plant species was evaluated. Totally 10 spatial scales of the surrounding landscape matrix in the scope of 2000 m (including WLFZ) were classified, and 14 landscape indices were applied to analyze the landscape matrix composition and configuration. Using the principal component analysis and correlation analysis, the effects of landscape matrix on the alien invasive plant species and associated scale effect were tested. Results showed that a total of 42 alien invasive plant species were found in the WLFZ, belonging to 17 families and 36 genera. Fuling was a dividing place to differentiate invasive species distribution. The number of the alien invasive species between Fuling and the Three Gorges Dam was found more than that between Fuling and Jiangjin. For the all scales (within 2000 m). The higher the landscape matrix fragmentation was, the more difficult the alien species invading. The higher landscape connectivity was, the easier the alien species invading. The effects of landscape matrix composition and configuration on the invasive plant diversity at large scales (1200-2000 m) was more significant than those at small scales (200-1000 m), in which landscape matrix composition and configuration at 1200-1400 m showed the strongest effect, demonstrating a significant spatial scale effect. Different invasive plant species showed the scale effects of landscape matrix composition and configuration. At all scales, Xanthium strumarium and Bidens frondosa showed weak correlations with landscape indices, but Bidens tripartita and Erigeron canadensis showed strong correlations. Landscape matrix was closely related to invasive plant species, and demonstrated a significant scale effect. The alien invasive plant species could be traced to the landscape matrix at large scales. Grassland and forest patches at the small scales could be used as the 'stepping stone' for the alien species transiting before they arrived at the WLFZ. In order to control alien plants in the WLFZ, land-use management and optimization should be strengthened at different scales of landscape matrix on the basis of enhancement of habitat management. A diversified comprehensive control for alien species should thus be taken into account.

Roadsides provide refuge for orchids: characteristic of the surrounding landscape.

Seminatural habitats are declining throughout the world; thus, the role of small anthropogenic habitats in the preservation of plants is becoming increasingly appreciated. Here, we surveyed the orchid flora of roadside verges in five Central European countries (Austria, Hungary, Romania, Slovakia, and Slovenia) and tested how the surrounding landscape matrix affects the overall number of species and individuals, and also different functional groups of orchids. We found more than 2,000 individuals of 27 orchid species during our surveys. According to our results, the increasing coverage of agricultural and urban areas negatively affects both the number of orchid species and individuals on roadsides. Our study further suggests that differences in the surrounding habitats affect which species are found on roadsides, since the increasing coverage of grasslands or forested areas around orchid occurrences had a significant positive effect on the number of grassland or forest-dwelling species and individuals, respectively. Most variance in orchid numerosity and diversity was explained by the cover of the suitable habitat types of the respective taxa in the surrounding landscape of the sampling points. This highlights the importance of roadsides acting as refugia for numerous species and valuable plant communities as well as in supporting biodiversity in general.

Landscape permeability and individual variation in a dispersal-linked gene jointly determine genetic structure in the Glanville fritillary butterfly.

There is now clear evidence that species across a broad range of taxa harbor extensive heritable variation in dispersal. While studies suggest that this variation can facilitate demographic outcomes such as range expansion and invasions, few have considered the consequences of intraspecific variation in dispersal for the maintenance and distribution of genetic variation across fragmented landscapes. Here, we examine how landscape characteristics and individual variation in dispersal combine to predict genetic structure using genomic and spatial data from the Glanville fritillary butterfly. We used linear and latent factor mixed models to identify the landscape features that best predict spatial sorting of alleles in the dispersal-related gene phosphoglucose isomerase (Pgi). We next used structural equation modeling to test if variation in Pgi mediated gene flow as measured by Fst at putatively neutral loci. In a year when the population was recovering following a large decline, individuals with a genotype associated with greater dispersal ability were found at significantly higher frequencies in populations isolated by water and forest, and these populations showed lower levels of genetic differentiation at neutral loci. These relationships disappeared in the next year when metapopulation density was high, suggesting that the effects of individual variation are context dependent. Together our results highlight that (1) more complex aspects of landscape structure beyond just the configuration of habitat can be important for maintaining spatial variation in dispersal traits and (2) that individual variation in dispersal plays a key role in maintaining genetic variation across fragmented landscapes.

Avian community characteristics and demographics reveal how conservation value of regenerating tropical dry forest changes with forest age.

Expansion of secondary forests following the abandonment of agriculture may have important implications for bird conservation, but few studies have examined the dynamics of this process. We studied bird use of a chronosequence of differently-aged abandoned pastures regenerating to dry forest to better understand how the value of these habitats to birds changes over time. In a five year study on Hispaniola, we recorded 7,315 net captures of 60 species of landbirds in sites that began the study at two, five, 10, and 20 years post-abandonment, and in mature native dry forest. Twenty-five species made up 97% of all net captures. Highest capture rates were in the two youngest sites. These early-successional habitats had many over-wintering Neotropical migrants; among residents, granivores and frugivores predominated. In contrast, both the twenty-year-old and mature forest sites had few migrants, more resident insectivores and omnivorous species, and a greater proportion of endemics. Age and sex ratios, body condition and site persistence suggest early successional sites were sub-optimal for most over-wintering migrants, but habitat improved with age for three migratory species; results for permanent residents varied among species. Remnant trees and understory shrubs in the agroecological matrix likely contributed to avian diversity in regenerating dry forest sites, and proximity to mature forest also likely affected the diversity and abundance of birds in regenerating habitat. Our study shows that regenerating forests do not fully compensate for loss of mature dry forest habitat, even after 24 years of regeneration; natural restoration of complex microhabitats in dry forest sites converted to agriculture may take decades or longer. The highest value of regenerating forests may be as habitat for some over-wintering Neotropical migrants, and in creating a buffer zone that enhances biodiversity conservation by re-integrating these lands into the protected tracts of mature forest needed by the islands more unique and endemic bird species.