Independent effects of habitat loss, habitat fragmentation and structural connectivity on the distribution of two arboreal rodents

Selection of Nest Material and Summer Nest Location by the Hazel Dormouse (Muscardinus avellanarius) in the Bidstrup Forests, Denmark

Hazel dormice (Muscardinus avellanarius) construct summer nests for resting and breeding. The nests are built directly in the vegetation, in tree hollows, or in nest boxes. The availability of nest materials and vegetation coverage may affect the likelihood of finding hazel dormice at a location. The aim of the study is: (1) To investigate the preferences of hazel dormice for nesting materials today compared to four decades ago. (2) To investigate hazel dormice preferences for vegetation coverage at nest sites. In total, 148 hazel dormouse summer nests from the Bidstrup forests in Zealand (Denmark), were analysed. Of these, 82 were collected in the period A: 1980−1985 and 66 were collected in B: 2019−2020. In total 26 different nest materials were found. Beech was the major nest material in both periods, and Jacob’s selectivity index indicates that beech is selected for as nesting material and that hazel dormice may travel to collect beech leaves. Nests from period A contained more beech (W = 1521, p < 0.05) and less oak (W = 1304, p < 0.01) compared to nests from period B. Vegetation analysis showed that coverage of shrubs higher than 2 m above ground (W = 1.5, p = 0.07) may be of great importance for hazel dormice.

Structural re-design of the Animex Wildlife Bridge for the Hazel Dormouse (Muscardinus avellanarius): lessons learnt from two connectivity mitigation case studies in the UK

The Hazel Dormouse (Muscardinus avellanarius) is an arboreal mammal present in Europe and Asia minor. The population is declining in the United Kingdom (UK), partially due to habitat fragmentation caused by the development of linear infrastructure such as roads, railways and pipelines. In 2016, we designed and tested an arboreal bridge in Britain that was proven to be effective for Hazel Dormice. Subsequently, the bridge materials were upgraded to meet the technical standards of UK road agencies, so that it could be approved and implemented as mitigation on projects throughout the UK. In the UK, each bridge must be certified for technical approval by the relevant road authority and as the bridge is a unique structure, this can pose challenges on projects. The national safety standards of UK roads would not allow common methods used for arboreal bridges across the world to be applied, so we needed specialised engineering and design adaptations to be implemented. Two overarching installation designs were created: the standalone bridge and the retrofit bridge. Several bridges have now been installed across roads in the UK and we will be discussing the development and implementation process from two case studies: i) a 40-metre retrofit bridge to an underpass in St Athan, Wales and, ii) two 76+ metre bridges retrofit to an overbridge and underpass on the M1 motorway in Gayhurst, Buckinghamshire. The St Athan project was quickly approved and easily installed while the M1 project required several alterations to the design and installation methods to meet specific project requirements. This paper discusses what we have learned from these projects, how these projects have influenced the future designs of the Animex wildlife bridge and how this could be applied to future arboreal wildlife connectivity bridges across the world.

Designing cross-region ecological compensation scheme by integrating habitat maintenance services production and consumption-A case study of Jing-Jin-Ji region

Establishing a practicable ecological compensation scheme is crucial to raise sufficient funds for habitat conservation. This study proposes a cross-region ecological compensation scheme by integrating habitat maintenance services production and consumption. In addition, the suitability evaluation method and InVEST model of habitat quality were employed to estimate the habitat maintenance services production and consumption, respectively. We used 1980 as the benchmark year and applied the scheme to a three-level hierarchy of the Jing-Jin-Ji region for 2000, 2008 and 2013. At the provincial level, Beijing paid the most habitat maintenance services ecological compensation, with an increasing trend from 1.64 × 109 RMB to 2.22 × 109 RMB, and Hebei received the most, from 2.06 × 109 RMB to 2.72 × 109 RMB. At the municipal level, Chengde, which is the most underdeveloped region in Hebei, was the largest beneficiary, receiving 1.31 × 109 RMB, 1.42 × 109 RMB and 1.46 × 109 RMB, respectively, and the ratio of ecological compensation to fiscal revenue was 7.59%. At the county level, Fengning and Weichang, the top two underdeveloped counties in Chengde, received the highest compensation. The results are consistent with each region's ecological function positioning and economic development status of the Jing-Jin-Ji region. This study can clarify the ecological responsibilities and rights, and provides the suggestions for establishing the cross administrative region ecological compensation scheme and long-term funding mechanism for habitat conservation.

Wildlife conservation in a fragmented landscape: the Eurasian red squirrel on the Isle of Wight

Island populations may have a higher extinction risk due to reduced genetic diversity and need to be managed effectively in order to reduce the risk of biodiversity loss. The Eurasian red squirrels (Sciurus vulgaris) in the south of England only survive on three islands (the Isle of Wight, Brownsea and Furzey islands), with the Isle of Wight harbouring the largest population in the region. Fourteen microsatellites were used to determine the genetic structure of red squirrel populations on the Isle of Wight, as well as their relatedness to other populations of the species. Our results demonstrated that squirrels on these islands were less genetically diverse than those in Continental mainland populations, as would be expected. It also confirmed previous results from mitochondrial DNA which indicated that the squirrels on the Isle of Wight were relatively closely related to Brownsea island squirrels in the south of England. Importantly, our findings showed that genetic mixing between squirrels in the east and west of the Isle of Wight was very limited. Given the potential deleterious effects of small population size on genetic health, landscape management to encourage dispersal of squirrels between these populations should be a priority.

Impact of land use changes on soil quality and species diversity in the Vindhyan dry tropical region of India

Conversion of forest land into different land use types is the primary cause of degradation of land resources, which in turn alters nutrient and carbon cycles, land productivity and diversity of species. There is scarcity of information about land-use changes (LUC) and their effect on relationship of soil quality and species diversity at landscape level in the Vindhyan dry tropical region. We evaluated the impact of land-use changes on soil physicochemical quality and the influence of these qualities on species diversity and organic matter accumulation. We also established the relationship between soil quality indicators and species diversity parameters. To examine impact of LUC, we did a detailed field survey and analysed selected soil quality indicators by standard methods. We examined species diversity parameters and established the relationship between soil quality and species diversity. We found that there is a marked decline in soil porosity, water-holding capacity and soil moisture due to LUC. Conversion from forest land (FL) to savanna land (SL) resulted in soil organic carbon decreasing by ∼40–50%. The decrease was more pronounced in cultivated land (CL) and degraded land (DL) (65–70% and 83–85%, respectively). In the case of total N, maximum decrease in total N of 83–87% was noted in DL as compared with FL. The poor soil quality indicators in degraded and agricultural land can be explained by the interaction between the soil organic carbon and nitrogen loss with diversity loss. This study recommends that for management/restoration of land resources, planning strategies should consider the current landscape structure, with land-use planning.

Hedgerow typology and condition analysis to inform greenway design in rural landscapes

Over the past decades, Western European hedgerows have been declining as a result of land use change. Disused infrastructure corridors such as railways and tramways can host a range of existing and returning semi-natural habitats, including extensive hedgerow networks. However, long term corridor abandonment can result in network deterioration to gappy hedgerows, lines of trees and eventually individual scrub features. The loss of hedgerows results in the loss of many ecosystem services, habitat for species and landscape connectivity. This highlights an increasing need to find innovative solutions to recognise and appropriately maintain these hedgerow networks. European Greenways typically 'upcycle' disused infrastructure transport corridors for multi-use, non-motorised recreational public infrastructure. The potential for European greenways to maintain and restore hedgerows is of interest as a novel planning mechanism for enhancing green infrastructure in general. The aim of this study is to inform Greenway design and management through the evaluation of hedgerow significance (historical, ecological and landscape), condition and composition within a rural European Greenway landscape context. 81 hedgerows were sampled along a 70 km proposed Greenway route traversing a range of extensive and intensive landscapes. Hedgerows were surveyed using a rapid field score sheet which enabled significance and condition scoring. A hedgerow typology was subsequently developed based on species composition assemblages. Hedgerows were found to be highly ecologically significant and species rich throughout the route. On-going land use intensification was evident as significant sections of the former railway corridor were subsumed into intensive agriculture and afforestation. Management recommendations need to be adapted to the particular hedgerow group and surrounding landscape context, and take into account the varied requirements of different taxonomic groups. The study findings show Greenways have the potential to act as multi-functional green infrastructure (accomplishing both ecological and recreational objectives) through informed design to reinforce their nature conservation role and recognising hedgerows as integral landscape feature of Greenway corridor, at local level and as part of a wider European network.

Species specialization limits movement ability and shapes ecological networks: the case study of 2 forest mammals

To counteract the negative effects of forest fragmentation on wildlife, it is crucial to maintain functional ecological networks. We identified the ecological networks for 2 mammals with very different degrees of forest specialization, the European badger Meles meles and the Roe deer Capreolus capreolus, by differentiating 4 agroforestry elements as either nodes or connectivity elements, and by defining the distance that provides the functional connectivity between fragments. Species occurrence data were collected in a wide agroecosystem in northern Italy. To test the role of hedgerows, traditional poplar cultivations, short rotation coppices, and reforestations as ecological network elements for the 2 species we applied the method of simulated species perceptions of the landscape (SSPL), comparing the ability of different SSPLs to explain the observed species distribution. All analyses were repeated considering different scenarios of species movement ability through the matrix. Model outputs seem to show that the specialist and highly mobile Roe deer has the same movement ability throughout the matrix (2 km) as the European badger, a smaller, but generalist species. The ecological network identified for the European badger was widespread throughout the area and was composed of woodlands, poplar cultivations and hedgerows as nodes and short rotation coppices as connectivity elements. Conversely, the ecological network of the Roe deer was mostly limited to the main forest areas and was composed of woodlands, poplar cultivations and reforestations as nodes and short rotation coppices and hedgerows as connectivity elements. The degree of forest specialization strongly affects both species perception of habitat and movement ability throughout the matrix, regardless of species size. This has important implications for species conservation.

Multilevel landscape utilization of the Siberian flying squirrel: Scale effects on species habitat use

Animals use and select habitat at multiple hierarchical levels and at different spatial scales within each level. Still, there is little knowledge on the scale effects at different spatial levels of species occupancy patterns. The objective of this study was to examine nonlinear effects and optimal-scale landscape characteristics that affect occupancy of the Siberian flying squirrel, Pteromys volans, in South- and Mid-Finland. We used presence-absence data (n = 10,032 plots of 9 ha) and novel approach to separate the effects on site-, landscape-, and regional-level occupancy patterns. Our main results were: landscape variables predicted the placement of population patches at least twice as well as they predicted the occupancy of particular sites; the clear optimal value of preferred habitat cover for species landscape-level abundance is a surprisingly low value (10% within a 4 km buffer); landscape metrics exert different effects on species occupancy and abundance in high versus low population density regions of our study area. We conclude that knowledge of regional variation in landscape utilization will be essential for successful conservation of the species. The results also support the view that large-scale landscape variables have high predictive power in explaining species abundance. Our study demonstrates the complex response of species occurrence at different levels of population configuration on landscape structure. The study also highlights the need for data in large spatial scale to increase the precision of biodiversity mapping and prediction of future trends.

Landscape distribution of food and nesting sites affect larval diet and nest size, but not abundance of Osmia bicornis

Habitat fragmentation is a major threat for beneficial organisms and the ecosystem services they provide. Multiple-habitat users such as wild bees depend on both nesting and foraging habitat. Thus, they may be affected by the fragmentation of at least two habitat types. We investigated the effects of landscape-scale amount of and patch isolation from both nesting habitat (woody plants) and foraging habitat (specific pollen sources) on the abundance and diet of Osmia bicornis L. Trap-nests of O. bicornis were studied in 30 agricultural landscapes of the Swiss Plateau. Nesting and foraging habitats were mapped in a radius of 500 m around the sites. Pollen composition of larval diet changed as isolation to the main pollen source, Ranunculus, increased, suggesting that O. bicornis adapted its foraging strategy in function of the nest proximity to main pollen sources. Abundance of O. bicornis was neither related to isolation or amount of nesting habitat nor to isolation or abundance of food plants. Surprisingly, nests of O. bicornis contained fewer larvae in sites at forest edge compared to isolated sites, possibly due to higher parasitism risk. This study indicates that O. bicornis can nest in a variety of situations by compensating scarcity of its main larval food by exploiting alternative food sources.

Fragment size does not matter when you are well connected: effects of fragmentation on fitness of coexisting gypsophiles

Most habitat fragmentation studies have focused on the effects of population size on reproductive success of single species, but studies assessing the effects of both fragment size and connectivity, and their interaction, on several coexisting species are rare. In this study, we selected 20 fragments along two continuous gradients of size and degree of isolation in a gypsum landscape in central Spain. In each fragment, we selected 15 individuals of each of three dominant gypsophiles (Centaurea hyssopifolia, Lepidium subulatum and Helianthemum squamatum, 300 plants per species, 900 plants in total) and measured several reproductive traits: inflorescence number, fruit set, seed set and seed mass. We hypothesised that plant fitness would be lower on small and isolated fragments due to an interaction between fragment size and connectivity, and that response patterns would be species-specific. Overall, fragment size had very little effect on reproductive traits compared to that of connectivity. We observed a positive effect of fragment connectivity on C. hyssopifolia fitness, mediated by the increased seed predation in plants from isolated fragments, resulting in fewer viable seeds per capitulum and lower seed set. Furthermore, seed mass was lower in plants from isolated fragments for both C. hyssopifolia and L. subulatum. In contrast, few reproductive traits of H. squamatum were affected by habitat fragmentation. We discuss the implications of species-specific responses to habitat fragmentation for the dynamics and conservation of gypsum plant communities. Our results highlight the complex interplay among plants and their mutualistic and antagonistic visitors, and reinforce the often-neglected role of habitat connectivity as a key component of the fragmentation process.

Influence of land mosaic composition and structure on patchy populations: the case of the water vole (Arvicola sapidus) in Mediterranean farmland

The ability of patchy populations to persist in human-dominated landscapes is often assessed using focal patch approaches, in which the local occurrence or abundance of a species is related to the properties of individual patches and the surrounding landscape context. However, useful additional insights could probably be gained through broader, mosaic-level approaches, whereby whole land mosaics with contrasting patch-network and matrix characteristics are the units of investigation. In this study we addressed this issue, analysing how the southern water vole (Arvicola sapidus) responds to variables describing patch-network and matrix properties within replicated Mediterranean farmland mosaics, across a gradient of agricultural intensification. Patch-network characteristics had a dominant effect, with the total amount of habitat positively influencing both the occurrence of water voles and the proportion of area occupied in land mosaics. The proportions of patches and area occupied by the species were positively influenced by mean patch size, and negatively so by patch isolation. Matrix effects were weak, although there was a tendency for a higher proportion of occupied patches in more intensive, irrigated agricultural landscapes, particularly during the dry season. In terms of conservation, results suggest that water voles may be able to cope well with, or even be favoured by, the on-going expansion of irrigated agriculture in Mediterranean dry-lands, provided that a number of patches of wet herbaceous vegetation are maintained within the farmland mosaic. Overall, our study suggests that the mosaic-level approach may provide a useful framework to understand the responses of patchy populations to land use change.

Effects of habitat fragmentation on abundance, larval food and parasitism of a spider-hunting wasp

Habitat fragmentation strongly affects species distribution and abundance. However, mechanisms underlying fragmentation effects often remain unresolved. Potential mechanisms are (1) reduced dispersal of a species or (2) altered species interactions in fragmented landscapes. We studied if abundance of the spider-hunting and cavity-nesting wasp Trypoxylon figulus Linnaeus (Hymenoptera: Crabronidae) is affected by fragmentation, and then tested for any effect of larval food (bottom up regulation) and parasitism (top down regulation). Trap nests of T. figulus were studied in 30 agricultural landscapes of the Swiss Plateau. The sites varied in the level of isolation from forest (adjacent, in the open landscape but connected, isolated) and in the amount of woody habitat (from 4 % to 74 %). We recorded wasp abundance (number of occupied reed tubes), determined parasitism of brood cells and analysed the diversity and abundance of spiders that were deposited as larval food. Abundances of T. figulus were negatively related to forest cover in the landscape. In addition, T. figulus abundances were highest at forest edges, reduced by 33.1% in connected sites and by 79.4% in isolated sites. The mean number of spiders per brood cell was lowest in isolated sites. Nevertheless, structural equation modelling revealed that this did not directly determine wasp abundance. Parasitism was neither related to the amount of woody habitat nor to isolation and did not change with host density. Therefore, our study showed that the abundance of T. figulus cannot be fully explained by the studied trophic interactions. Further factors, such as dispersal and habitat preference, seem to play a role in the population dynamics of this widespread secondary carnivore in agricultural landscapes.

Large forest patches promote breeding success of a terrestrial mammal in urban landscapes

Despite a marked increase in the focus toward biodiversity conservation in fragmented landscapes, studies that confirm species breeding success are scarce and limited. In this paper, we asked whether local (area of forest patches) and landscape (amount of suitable habitat surrounding of focal patches) factors affect the breeding success of raccoon dogs (Nyctereutes procyonoides) in Tokyo, Central Japan. The breeding success of raccoon dogs is easy to judge as adults travel with pups during the breeding season. We selected 21 forest patches (3.3-797.8 ha) as study sites. In each forest patch, we used infra-red-triggered cameras for a total of 60 camera days per site. We inspected each photo to determine whether it was of an adult or a pup. Although we found adult raccoon dogs in all 21 forest patches, pups were found only in 13 patches. To estimate probability of occurrence and detection for raccoon in 21 forest fragments, we used single season site occupancy models in PRESENCE program. Model selection based on AIC and model averaging showed that the occupancy probability of pups was positively affected by patch area. This result suggests that large forests improve breeding success of raccoon dogs. A major reason for the low habitat value of small, isolated patches may be the low availability of food sources and the high risk of being killed on the roads in such areas. Understanding the effects of local and landscape parameters on species breeding success may help us to devise and implement effective long-term conservation and management plans.

Remnant fragments within an agricultural matrix enhance conditions for a rodent host and its fleas

Habitat fragmentation can adversely impact biodiversity, although where remnant fragments of natural vegetation provide favourable conditions the negative effects of fragmentation may be mitigated. Host-parasite systems in fragmented areas have only recently been examined, with parasites generally showing higher prevalence and richness in fragments, mediated by changes in host density. However, the effect of fragmentation on parasite body size and fecundity remains poorly investigated. Thus, here we compared the body size and condition of a generalist rodent host, Rhabdomys pumilio and the body size of 2 common flea species between pristine natural areas and remnant fragments within agriculture areas. Host body length, weight and body condition values were significantly larger in fragments than in pristine natural vegetation. Listropsylla agrippinae fleas showed the same pattern, being significantly larger in fragments, while Chiastopsylla rossi fleas did not differ in size between fragments and natural areas. The differential response of the 2 flea species may reflect the strength of association between the host and parasite, with the former spending a greater proportion of its lifespan on the host. Therefore, in this study agriculture fragments provide better conditions for both an opportunistic rodent and a closely associated flea species.