Stone marten (Martes foina) habitat in a Mediterranean ecosystem: effects of scale, sex, and interspecific interactions

Mediterranean ecosystems are inherently patchy, challenging habitat-use behavior. Certain mammalian carnivores take advantage of this patchiness by a strategy of habitat complementation/supplementation, which is invariant to the scale of analysis. To test if the same behavior is adopted by the stone marten, we used a combined data set of capture and radio-tracking data at three scales of analysis (1-m, 25-m, and 452-m radius plots). We used compositional analysis to test if there were sex-specific differences in foraging and resting habitat use of stone martens and if these patterns were affected by the presence of other mesocarnivores. Our results showed that stone martens are found both in rural and forested landscapes. Foraging and resting activities occurred far from roads in large and complex patches of cork oak woodlands, riparian vegetation, orchards, and pastureland. Use varied with the scale of analysis and the sex. At smaller scales, females use pastures for foraging and orchards for resting, whereas riparian vegetation and sparse cork oak forests influenced this use at larger scales. Males, on the other hand, were more consistent across scales, using riparian areas and dense cork oak woodlands for foraging and pastures for resting. Stone martens shared the same areas with other coexisting mesocarnivores. Stone martens use cork oak woodlands and complement/supplement this use with other land cover types. The consistent use of cork oak woodlands across scales emphasizes the importance of this land cover to the preservation of functional Mediterranean ecosystems in southern Portugal.     

Do riparian forest strips in modified forest landscapes aid in conserving bat diversity?

Agricultural practices lead to losses of natural resources and biodiversity. Maintaining forests alongside streams (riparian forest strips) has been used as a mechanism to minimize the impact of clearing for agriculture on biodiversity. To test the contribution of riparian forest strips to conserve biodiversity in production landscapes, we selected bats as a biodiversity model system and examined two dimensions of diversity: taxonomic and functional. We compared bat diversity and composition in forest, with and without stream habitat, and in narrow forest riparian strips surrounded by areas cleared for agriculture. We tested the hypothesis that riparian forest strips provide potential conservation value by providing habitat and serving as movement corridors for forest bat species. Riparian forest strips maintained 75% of the bat species registered in forested habitats. We found assemblage in sites with riparian forest strips were dominated by a few species with high abundance and included several species with low abundance. Bat species assemblage was more similar between sites with streams than between those sites to forests without stream habitat. These results highlight the importance of stream habitat in predicting presence of bat species. We registered similar number of guilds between forest sites and riparian forest strips sites. Relative to matrix habitats, stream and edge habitats in riparian forest strips sites were functionally more diverse, supporting our hypothesis about the potential conservation value of riparian forest strips. Results from this study suggest that maintaining riparian forest strips within cleared areas for agricultural areas helps conserve the taxonomic and functional diversity of bats. Also, it provides basic data to evaluate the efficacy of maintaining these landscape features for mitigating impacts of agricultural development on biodiversity. However, we caution that riparian forest strips alone are not sufficient for biodiversity maintenance; their value depends on maintenance of larger forest areas in their vicinity.     

Maintenance of ladybeetle diversity across a heterogeneous African agricultural/savanna land mosaic

The importance of agricultural land for maintaining indigenous biodiversity is an important contemporary issue. A large agricultural estate in Swaziland, which is a mosaic of citrus orchards, exotic tree windbreaks, indigenous riparian vegetation and savanna was investigated. The distribution of larval and adult coccinellids within the habitat types, and the relative influences of temperature, relative humidity, ground insolation and prey presence was assessed over a 2-year period. The highest coccinellid densities and species richness occurred within the orchards. Riparian habitats on the boundaries of the estate were closer to the orchard habitat in species composition than was the natural savanna. Not surprisingly, the presence/absence of prey was the most important variable which determined coccinellid distribution and density in the agricultural landscape. Relative humidity, temperature and ground insolation had no significant effect on coccinellid densities. Some species, such as the exotic Cheilomenes lunata, and the indigenous Scynmus sp. and Nephus sp. were widely dispersed and occurred in all habitats, while the economically important but exotic species, Rodolia cardinalis was only within the citrus orchards. Overall, the coccinellid assemblage was not a good indicator of habitat type. Nevertheless, a variety of habitat types (i.e. a heterogenous landscape) appear to be essential for the survival of most coccinellids. Indeed, the heterogeneous agricultural and natural land mosaic provides maximum plant diversity and hence coccinellid diversity, thus increasing the potential for natural control of pest prey species in the orchards, while at the same time maximizing survival of indigenous coccinellids.     

An ecosystem engineer,the beaver,increases species richness at the landscape scale

Ecosystem engineering - the physical modification of habitats by organisms - has been proposed as an important mechanism for maintaining high species richness at the landscape scale by increasing habitat heterogeneity. Dams built by beaver (Castor canadensis) dramatically alter riparian landscapes throughout much of North America. In the central Adirondacks, New York, USA, ecosystem engineering by beaver leads to the formation of extensive wetland habitat capable of supporting herbaceous plant species not found elsewhere in the riparian zone. We show that by increasing habitat heterogeneity, beaver increase the number of species of herbaceous plants in the riparian zone by over 33% at a scale that encompasses both beaver-modified patches and patches with no history of beaver occupation. We suggest that ecosystem engineers will increase species richness at the landscape scale whenever there are species present in a landscape that are restricted to engineered habitats during at least some stages of their life cycle.     

Limited Effects of Large‐Scale Riparian Restoration on Seed Banks in Agriculture

I examined the effect of riparian forest restoration on plant abundance and diversity, including weed species, on agricultural lands along the Sacramento River in California (United States). Riparian forest restoration on the Sacramento River is occurring on a large‐scale, with a goal of restoring approximately 80,000 ha over 160 km of the river. In multiuse habitats, such as the Sacramento River, effects of adjoining habitat types and movement of species across these habitats can have important management implications in terms of landscape‐scale patterns of species distributions. Increased numbers of pest animals and weeds on agricultural lands associated with restored habitats could have negative economic impacts, and in turn affect support for restoration of natural areas. In order to determine the distribution and abundance of weeds associated with large‐scale restoration, I collected seed bank soil samples on orchards between 0 and 5.6 km from adjacent restored riparian, remnant riparian, and agricultural habitats. I determined the abundance, species richness, and dispersal mode of plant species in the seed bank and analyzed these variables in terms of adjacent habitat type and age of restored habitat. I found that agricultural weed species had higher densities at the edge of restored riparian habitat and that native plants had higher densities adjacent to remnant riparian habitat. Weed seed abundance increased significantly on walnut farms adjacent to restored habitat with time since restored. I supply strong empirical evidence that large areas of natural and restored habitats do not lead to a greater penetration of weed species into agricultural areas, but rather that weed penetration is both temporally and spatially limited.     

Orchard and riparian habitats enhance ground dwelling beetle diversity in Mediterranean agro-forestry systems

The relative contribution of mixed orchard and riparian vegetation patches to local and regional diversity of Mediterranean landscapes dominated by cork-oak woodlands was tested in 2006–2007 using ground, rove and darkling beetles (Coleoptera: Carabidae, Staphylinidae, Tenebrionidae). Mixed orchard and riparian gallery habitats recorded higher values of abundance and species richness for overall beetle species, although most darkling beetle species were associated with the sclerophyllous cork-oak woodlands. Ground and rove beetle community structure changed from the orchard and riparian habitats to samples placed 100 m away into the surrounding cork-oak woodland, i.e., non-cork-oak patches enhanced beta diversity within the landscape mosaic. Analysis of ground beetle traits concerning moisture preferences revealed a higher proportion of hygrophilous species in mixed orchard and riparian gallery habitats while xerophilous species were dominant within the cork-oak woodlands. The results of this study suggested that land-use management promoting the maintenance of habitat heterogeneity enhances biodiversity conservation of important hygrophilous and xerophilous species, and subsequently the sustainable use of Mediterranean agro-forest mosaics.     

Restore it,and they will come: trap-nesting bee and wasp communities (Hymenoptera: Aculeata) are recovered by restoration of riparian forests

Riparian forests have been greatly affected by anthropogenic actions with formerly continuous riparian forests being slowly converted into small and isolated patches. Riparian forests are extremely important habitats for many groups of insects, including bees and wasps, because they are sources of shelter and food for them and their offspring. There is a growing body of evidence of success in the restoration of riparian forest plant communities; however, little research has been done on the associated invertebrate communities. We test whether restoring plant communities is sufficient for restoring the taxonomic composition of trap-nesting bees and wasps and which functional traits are favored in different sites. We predict that species richness, abundance, and community composition of trap-nesting bees and wasps of riparian sites undergoing restoration will converge on the “target” of a reference site with increasing time, since restoration increases habitat complexity. We also predict that the width of restored patches will also influence the species richness, abundance and community composition of trap-nesting bees and wasps. Bee richness and abundance, and wasp richness, were strongly related to fragment width, but not to age since restoration. Our results indicate that although restored sites are relatively small and scattered in a fragmented landscape, they provide suitable habitat for re-colonization by community assemblages of trap-nesting bees and wasps and the traits selected captured the responses to the habitat restoration. Hence, restored riparian areas can be considered important habitats for invertebrates, thus contributing to an increase in local biodiversity and, possibly, the restoration of some of the ecosystem services they originally provided.     

垫状植物囊种草对群落物种多样性的影响

在甘肃盐池湾国家级自然保护区内海拔4137 m处,选择典型的囊种草垫状植被设置研究样地,研究了垫状植物囊种草对群落物种组成和群落物种多样性的影响,并且定量的研究了囊种草对群落物种丰富度的影响能力和维持潜力。研究结果表明:囊种草为群落中增加了新的植物种类,并且提高了部分生境一般种的多度;囊种草的出现提高了群落物种密度和物种丰富度,进而提高了群落物种多样性;囊种草斑块的增加将会引起景观水平物种丰富度的增加,表明囊种草具有为群落中引入新的植物种类进而提高群落物种丰富度的能力;在景观水平,囊种草所创造的生境多样性则成为一种保障,可以维持景观中物种丰富度从而降低物种损失的风险,表明囊种草具有较高的群落物种丰富度维持潜力。     

Use of Tropical Dry Forests and Agricultural Areas by Neotropical Bird Communities

Agricultural activities represent a global threat to biodiversity, yet little is known about the relative importance of different agricultural land uses in relation to their wildlife communities. We explored bird community structure, diversity, and composition in a landscape dominated by primary tropical dry forest, and in three agricultural systems (i.e., tree orchards, herbaceous cropfields, cattle pastures) to evaluate the way in which birds use different habitats within the landscape. Tropical dry forests had the highest species richness and community evenness, although the bird community in tree orchards was also relatively species rich and even. Cattle pastures had more bird species than cropfields but both habitats were comparatively species poor with low evenness. Our results are related to habitat structure and the spatial location of sites within the landscape matrix. Based on our observations, we recommend including native tree species within agricultural systems and surrounding areas to provide additional resources for birds. Finally, we suggest promoting natural recruitment of native trees and shrubs within cattle pastures to provide suitable habitat for species that use tropical dry forest plants. Abstract in Spanish is available at http://www.blackwell‐synergy.com/loi/btp .     

Living on the verge: are roads a more suitable refuge for small mammals than streams in Mediterranean pastureland?

The retention of natural habitat corridors is a useful and practical conservation tool that can attenuate the effects of habitat loss and fragmentation on wildlife. Linear structures may contribute to the conservation of biodiversity by providing additional habitats for small fauna living in highly modified environments. We assessed the importance of road verges as refuge areas for small mammals, in highly intensified grazed pastures, within a Mediterranean landscape and compared the role of road verges as refuges with that of riparian galleries, which have been described as important shelter locations for small fauna. For this purpose, a small mammal trapping study was undertaken on two road verges and beside two small streams in southern Portugal. We captured 457 individuals of five different species, with Mus spretus the most common species captured, followed by Crocidura russula. Captures were 4.6-fold higher immediately beside both roads and streams than 12 m away in the surrounding matrix. Individuals captured in the matrix presented a smaller body size and lower body condition, suggesting that this suboptimal habitat is occupied mainly by subadults. M. spretus was 46% more abundant by roads than by streams, while C. russula was present in similar numbers in both habitats. M. spretus individuals were larger near streams but exhibited no difference in body condition between habitats. C. russula had a better body condition and slightly higher body lengths at roadsides. Our results show that roadside verges in intensively grazed Mediterranean landscapes act as important refuges and constitute equally vital habitats for small mammals as do riparian vegetation strips in landscapes where other suitable habitats are scarce.     

Single large AND several small habitat patches: A community perspective on their importance for biodiversity

The debate whether single large or several small (SLOSS) patches benefit biodiversity has existed for decades, but recent literature provides increasing evidence for the importance of small habitats. Possible beneficial mechanisms include reduced presence of predators and competitors in small habitat areas or specific functions such as stepping stones for dispersal. Given the increasing amount of studies highlighting individual behavioral differences that may influence these functions, we hypothesize that the advantage of small versus large habitat patches not only depends on patch functionality but also on the presence of animal personalities (i.e., risk-tolerant vs. risk-averse). Using an individual-based, spatially-explicit community model, we analyzed the diversity of mammal communities in landscapes consisting of a few large habitat islands interspersed with different amounts and sizes of small habitat patches. Within these heterogeneous environments, individuals compete for resources and form home-ranges, with only risk-tolerant individuals using habitat edges. Results show that when risk-tolerant individuals exist, small patches increase species diversity. A strong peak occurs at approximately 20% habitat cover in small patches when those small habitats are only used for foraging but not for breeding and home-range core position. Additional usage as stepping stones for juvenile dispersal further increases species persistence. Overall, our results reveal that a combination of a few large and several small habitat patches promotes biodiversity by enhancing landscape heterogeneity. Here, heterogeneity is created by pronounced differences in habitat functionality, increasing edge density, and variability in habitat use by different behavioral types. The finding that a combination of single large AND several small (SLASS) patches is needed for effective biodiversity preservation has implications for advancing landscape conservation. Particularly in structurally poor agricultural areas, modern technology enables precise management with the opportunity to create small foraging habitats by excluding less profitable agricultural land from cultivation.     

Cork oak woodlands in the north Tyrrhenian area (Italy): distribution and plant species diversity of a relict forest ecosystem

Italian north Tyrrhenian regions harbour pure or nearly pure cork oak woodlands towards the NE limit of the species range and the highest proportion of the habitat on mainland Italy, but their distribution, biodiversity and conservation status are still poorly known. Focusing on the key region of Tuscany, we analysed distribution and plant species richness of these forests based on literature and original field data. The habitat covers about 5.730?ha and is strongly fragmented for natural and non-natural reasons, underscoring its relict character. Out of the 420 plant taxa recorded, 19 were listed in IUCN categories at the national or regional level. Taxonomic singularity was especially high at the genus rank. Three neighbouring areas with different soil conditions and forest structure were compared based on field surveys, sample plots and linear transects from dense stands to shrub and herbaceous communities of small openings. The Versegge site showed the highest species richness at the area-scale and the mean diversity at the plot scale, representing a key biotope for the conservation of the habitat. However, the geographic–floristic covariation between the three sites suggested that a network of small areas would be more effective than a single, large area to protect the most significant components of the local cork oak flora. The Lattaia and Terzo areas may play an important role as corridor sites between the four SCIs of the Rete Natura 2000 network including cork oak communities on the Tuscan mainland. Species richness was higher in the stands with lower cork oak basal area, and there was a significant increase in species number along transects reaching openings caused by traditional human activities. A minor anthropic disturbance of traditional type may help to preserve the fine-scale habitat heterogeneity and the biodiversity of the whole ecosystem.     

Invasion impacts on biodiversity: responses of ant communities to infestation by cat’s claw creeper vine, <Emphasis Type="Italic">Macfadyena</Emphasis><Emphasis Type="Italic">unguis</Emphasis>-<Emphasis Type="Italic">cati</Emphasis> (Bignoniaceae) in subtropical Australia

Ants are the dominant soil faunal group in many if not most terrestrial ecosystems, and play a key role in soil structure and function. This study documents the impacts of invasion by the exotic cat’s claw creeper vine, Macfadyena unguis-cati (L.) Gentry (Bignoniaceae) on surface-situated (epigaeic) and subterranean (hypogaeic) ant communities in subtropical SE Queensland Australia where it is a major environmental weed of riparian areas, rainforest communities and remnant natural vegetation, smothering standing vegetation and causing canopy collapse. Soil ants were sampled in infested and uninfested areas at eight sites spanning both riparian and non-riparian habitats in subtropical SE Queensland. Patterns of ant species composition and functional grouping in response to patch invasion status, landscape type and habitat stratum were investigated using ANOVA and non-metric multidimensional scaling ordination. The epigaeic and subterranean strata supported markedly different ant assemblages, and ant communities also differed between riparian and non-riparian habitats. However, M. unguis-cati invasion had a surprisingly limited impact. There was a tendency for ant abundance and species richness to be lower in infested patches, and overall species composition was different between infested and uninfested patches, but these differences were relatively small, and did not occur consistently across sites. There were changes in functional group composition that conformed to known functional group responses to environmental change, but these were similarly limited and inconsistent across sites. Our study has shown that ant communities are surprisingly resilient to invasion by M. unguis-cati, and serves as a warning against making assumptions about invasion impacts based on visual appearances.     

Response of rove beetles (Staphylinidae) to various habitat types and change in Southern Mexico

We evaluated changes in levels of diversity of copro-necrophilous staphylinids attracted to piles of cattle dung and rat carrion in four contrasting habitats (continuous oak forest, oak forest patches, savannah and ravines) in southeastern Mexico during 2005 and 2006. In total, 181 morpho-species (N = 9,875 individuals) of Staphylinidae were recorded, of which 40 were coprophiles, 98 were necrophiles, and 43 were present in both substrates. Ten species accounted for 65% of the total number of individuals, 68 species were represented by singletons, whereas 103 species registered intermediate abundances. Less disturbed habitats recorded higher levels of beetle diversity. A strong seasonality effect was recorded for necrophiles, but not for coprophiles. A beta diversity analysis suggested that continuous oak forest registered the lowest fauna similarity when contrasted to other habitats; yet beetle composition among oak forest patches, savannah and ravine remained comparable. Staphylinidae body size and trophic guilds differed significantly among habitats. The results of this study suggest that key habitats such as ravines may represent a more permanent and predictable habitat for beetles in highly seasonal landscapes, even at early stages, because this habitat is characterized by a slower turnover of Staphylinidae species than in the case of tropical oak patches or savannah habitats.     

Multi‐scale effects of habitat structure and landscape context on a vertebrate with limited dispersal ability (the brown‐throated sloth,Bradypus variegatus)

As human population, food consumption, and demand for forest products continue to rise over the next century, the pressures of land‐use change on biodiversity are projected to intensify. In tropical regions, countryside habitats that retain abundant tree cover and structurally complex canopies may complement protected areas by providing suitable habitats and landscape connectivity for a significant portion of the native biota. Species with low dispersal capabilities are among the most at risk of extinction as a consequence of land‐use change. We assessed how the spatial distribution of the brown‐throated sloth (Bradypus variegatus), a model species for a vertebrate with limited dispersal ability, is shaped by differences in habitat structure and landscape patterns of countryside habitats in north‐central Costa Rica using a multi‐scale framework. We quantified the influence of local habitat characteristics and landscape context on sloth occurrence using mixed‐effects logistic regression models. We recorded 27 sloths within countryside habitats and found that both local and landscape factors significantly influenced their spatial distribution. Locally, sloths favored structurally complex habitats, with greater canopy cover and variation in tree height and basal area. At the landscape scale, sloths demonstrated a preference for habitats with high proportions of forest and nearby large tracts of forest. Although mixed‐use areas and tree plantations are not substitutes for protected forests, our results suggest they provide important supplemental habitats for sloths. To promote the conservation and long‐term viability of sloth populations in the tropical countryside, we recommend that land managers retain structurally complex vegetation and large patches of native habitat.     

Riparian buffer zones as elements of ecological networks: Case study on Parnassius mnemosyne distribution in Estonia

Territorial ecological networks (in US and some other countries known as greenways) are coherent assemblages of areas representing the natural and semi-natural landscape elements that need to be conserved, managed or, where appropriate, enriched or restored in order to ensure the favourable conservation status of the ecosystems, habitats, species and landscapes across their traditional range. An ecologically compensating areas network is a hierarchical system with the following levels: (1) core areas, (2) buffer zones of core areas, (3) corridors and stepping stones, and (4) nature development and/or restoration areas that support resources, habitats and species. Rivers form natural ecological networks and riparian buffer zones of rivers are typical elements of ecological networks. We studied the distribution of Clouded Apollo (Parnassius mnemosyne) and its habitat requirements in Estonia. Seventy-eight percent of all Clouded Apollo observations were recorded in riparian meadows along the banks of rivers with riparian strips consisting of bushes and trees. Detailed study showed that the butterfly is in most cases associated with meadows with a riparian strip of alder. This is the habitat of the food plant (fumeworth—Corydalis solida) of the larvae, the feeding and mating place of adults, and the migration and hiding site for the Clouded Apollo. The population area and number of individuals have been increasing during the last years, and a new growing South-Estonian sub-population of Clouded Apollo has also been discovered in Estonia.     

Habitat selection by Ortolan Buntings Emberiza hortulana in post-fire succession in Catalonia: implications for the conservation of farmland populations

The Ortolan Bunting Emberiza hortulana is a long-distance migrant that has suffered major population declines across much of its European breeding range. While northern populations are bound largely to farmland, Mediterranean populations are largely confined to habitats subject to recurrent wildfires. Habitat selection of the Ortolan Bunting was assessed in a recently burnt area in Catalonia at landscape and habitat scales. A Zero-inflated Poisson procedure was used to model the abundance of birds in relation to landscape and habitat variables. The most parsimonious landscape model predicted the highest abundance on south-facing slopes, with a gradient above 10°. The most parsimonious habitat model showed a positive quadratic effect of bare ground and regenerating oak Quercus spp., with predicted optima for abundance around 20–30% and 20% cover, respectively. There was a clear relationship between predicted abundance of the Ortolan Bunting and post-fire regenerating oak shrubs. South-facing, moderately sloping areas were favoured and bare ground was a key feature of the species' habitat. A matrix combining patches of sparse oak shrubs and patches of bare ground appears to be the optimal breeding habitat in the Mediterranean. The maintenance or provision of similar habitat features, especially patches of bare ground, may prove crucial for the conservation of rapidly declining Ortolan Bunting populations on farmland across temperate Europe.     

Variable history of land use reduces the relationship to specific habitat requirements of a threatened aquatic insect

The hutchinsonian realized niche of a species is the most common tool for selecting the actions needed when restoring habitats and establishing conservation areas of species. However, defining the realized niche of a species is problematic due to variation across spatial and temporal scales. In this study we tested the hypothesis that habitat parameters defining the realized niche of a species can be derived from a regional study and that national changes in land use influence the perception of the realized niche across different landscapes. We described the realized habitat niche of the threatened dragonfly Leucorrhinia pectoralis, in four Estonian landscapes which all have undergone more than 20 years of habitat degradations. We recorded the presence/absence of L. pectoralis and measured 7 habitat variables for 140 lakes and ponds located in one restored and three un-restored landscapes. Lake size and proportion of short riparian vegetation were significantly positive parameters determining the presence of L. pectoralis across landscape types. The species was much more habitat specific in the restored landscape, with larger influence of other habitat parameters. Our data suggest that the realized niche of the species in the un-restored landscapes was constrained by the present-day habitats. The study demonstrate that if a species realized niche is derived from local distribution patterns without incorporating landscape history it can lead to an erroneous niche definition. We show that landscape restoration can provide knowledge on a species’ habitat dependencies before habitat degradation has occurred, provided that restoration mitigation reflects the former landscape characteristics.