Bat casualties by road traffic (Brno-Vienna)

We studied the impact of road E461, Brno-Vienna, on bat mortality, with the goal to predict this impact after the road has been reconstructed and turned into highway, R52. In the Czech territory, two proposed road sections of E461 were selected, 3.5 and 4.5 km long, and divided into segments 100 m in length. Bat carcasses were picked up from emergency stopping lanes, and bat activity was recorded by ultrasound detectors along the road and 100 m away on both sides from the central strip. From May to October 2007, 25 checks of bat mortality performed at weekly intervals revealed 119 bat carcasses representing 11 or 12 species.Pipistrellus nathusii, P. pygmaeus andMyotis daubentonii were the most frequent traffic casualties. The greatest mortality was documented from early July to mid-October, with a peak in September. Monitoring bat activity by ultrasound detectors (one night per month in May, June and September) yielded 12 bat species and 3 species couples (Myotis mystacinus/brandtii, M. emarginatus/alcathoe, Plecotus auritus/austriacus), mostly the same taxa as found dead on the road. Significantly greater bat numbers were revealed in the section where the road was situated between two artificial lakes, as compared to a road section without any lakes directly adjacent to the road. In the former section, significant correlation was found between the number of carcasses found and the activity detected, according to road segments.     

An indicator of forest dynamics using a shifting landscape mosaic

The composition of a landscape is a fundamental indicator in land-cover pattern assessments. The objective of this paper was to evaluate a landscape composition indicator called ‘landscape mosaic’ as a framework for interpreting land-cover dynamics over a 9-year period in a 360,000 km² study area in the southern United States. The indicator classified a land parcel into one of 19 possible landscape mosaic classes according to the proportions of natural, developed, and agriculture land-cover types in a surrounding 4.41-ha neighborhood. Using land-cover maps from remote sensing, the landscape mosaics were calculated for each 0.09-ha pixel in the study area in 1996 and 2005. Mosaic transition matrices estimated from the pixel change data were then used to develop two Markov chain models. A “landscape mosaic” model was a temporal model of the shifting landscape mosaic, based on the probability of landscape mosaic change for all pixels. A “forest security” model was the same, except that the Markov states were defined by both the landscape mosaic and the land-cover of each pixel, which allowed interpreting forest land-cover dynamics in the context of a shifting landscape mosaic. In the forest security model, the overall percentage of forest decreased from 33% in 2005 to 17% at steady-state, and there was little change in the relative distribution of existing forest area among landscape mosaic classes. In contrast, the landscape mosaic steady-state was reached later, and indicated that a maximum of 10% of total area was available for forest. The implication was that forest security depended ultimately on the dynamics of the landscape mosaics that contained forest, not on forest dynamics within those landscape mosaics.     

Mortality of vertebrates on a road crossing the Biebrza Valley (NE Poland)

Mortality of vertebrates was monitored on a local road running across Poland’s Biebrza River Valley during 2 years (August 2005–July 2006). On the basis of distance from the river and surrounding habitats, the road (of total length 2,510 m) was divided into three stretches. The road was monitored on foot by two people every month, over a few consecutive days. A total of 1,892 road kills representing at least 47 species were found. Of these, 90.7% were amphibians, 4.2% mammals, 3.1% birds and 2.0% reptiles. Most (70%) of the amphibians were anurans, with the common toad, common frog and moor frog among them together accounting for 82% of the total. Mortality among amphibians differed between months, most anurans dying in May and August, while a majority of Urodela are lost in October. The peaks in mortality were connected with the migration of adult amphibians in spring and juveniles in summer and autumn. The number of amphibians killed was greatest on the (wettest) stretch adjacent to the river and decreased with distance from it. Mortality among birds was highest in July—probably in association with the dispersal of young individuals. Among recorded mammalian road kills, there was a prevalence of small rodents (mainly voles) and insectivores (mainly shrews). Medium-sized mammals were found only accidentally. Mortality in general was conditioned by the number of anurans killed.     

Gap‐crossing decisions of forest birds in a fragmented landscape

Habitat loss and fragmentation are recognized as primary drivers of biodiversity loss worldwide. To understand the functional effects of habitat fragmentation on bird populations, data on movement across gaps in habitat cover are necessary, although rarely available. In this study, we used call playback to simulate a conspecific territorial intruder to entice birds to move through the landscape in a predictable and directional manner. We then quantified the probability of movement in continuous forest and across cleared gaps for two forest‐dependent species, the grey shrike‐thrush (Colluricincla harmonica) and the white‐throated treecreeper (Cormobates leucophaeus). Fifty‐four playback trials were conducted for each species across distances ranging from 25 to 480 m in continuous forest and 15–260 m across gaps in a forest‐agricultural landscape in southern Victoria, Australia. The probability of movement was significantly reduced by gaps in forest cover for both species. Shrike‐thrushes were six times more likely to move 170 m in continuous forest than to cross 170‐m gaps. The mean probability that treecreepers would cross any gap at all was less than 0.5, and they were three times less likely to move 50 m across a gap than through continuous forest. Both species displayed non‐linear responses to increasing gap distance: we identified a gap‐tolerance threshold of 85 m for the shrike‐thrush and 65 m for the treecreeper beyond which individuals were most unlikely to cross. The presence of scattered paddock trees increased functional connectivity for the shrike‐thrush, with individuals crossing up to 260 m when scattered trees were present. We conclude that gaps in habitat cover are barriers to movement, and that characteristics of the intervening matrix influence landscape permeability.     

Multidimensional analysis of landscape dynamics in a Central African forest-savannah mosaic

Most landscape cover assessments for conservation programmes rely largely on remote sensing analyses. These analyses, however, neglect how people inhabiting protected zones perceive and structure land cover. Using socio-ecological systems (SES) analysis in a forest-savannah mosaic on the Congo Basin forest edge (Democratic Republic of Congo), we investigated how human practices, landscape perceptions and land use patterns affected forest cover. We conducted remote sensing analysis using a Sentinel-2 satellite image and 187 GPS landmarks, producing a land cover map with 11 classes. Our results yielded an 81.85% correspondence with additional 164 GPS landmarks, a robust score in tropical areas. We conducted 40 individual interviews, eighteen focus group discussion workshops and nine months of participant observation of human practices to identify 19 land units and elaborate a granular SES system structuring the landscape. Integrating local knowledge and practices with general ecological and agronomic processes, we developed a landscape dynamics model revealing progressive forest colonisation of savannahs. Our methods demonstrate that a forest-edge landscape cover evaluation through remote sensing and local knowledge can contribute to finer-grained assessment of land cover and ecosystem services. This assessment can assist conservation efforts by considering local populations' practices on and perceptions of landscape change.     

道路生态学中的景观生态问题

道路具有重要的景观生态影响,是道路生态学研究的热点问题之一。本文综述了道路生态学的研究历程和概况,从基础理论研究、道路对生物和理化环境的影响、道路与景观格局以及道路与土地利用/覆盖变化4个方面论述了目前道路生态学中景观生态问题的主要研究内容,并根据现有的研究成果概括了该领域的主要研究方法,即生物调查、道路缓冲区/影响区分析、叠图分析和综合分析。提出中国道路生态学中景观生态问题研究存在的主要问题,并对该领域未来的研究热点进行了展望。     

Factors influencing herpetofauna abundance and diversity in a tropical agricultural landscape mosaic

Agricultural intensification and the associated factors, including land transformation, are among the major global threats affecting biodiversity especially herpetofauna. However, little information is available about how different factors shape herpetofauna species assemblages in agricultural landscape at different spatial scales from patch (125 – 250m) to the landscape (500 – 1000m). We assessed the diversity of amphibians and reptiles in areas under low and high degrees of agricultural intensification and explored different factors regulating diversity at different spatial scales using four sampling methods. Diversity and abundance of amphibians varied significantly between the two zones, but not for reptiles. Agricultural intensification index (AII), calculated based on agrochemical use and area under agriculture at 250m scale, seemed to affect amphibians both at patch as well as at 500m and 1000m landscape scales. The AII influenced reptilian diversity only at patch and 500m scales. Vicinity of natural forest had a stronger influence on reptilian abundance. Seminatural vegetation impacted herpetofauna diversities at larger spatial scales. The extent of water bodies influenced the reptilian abundance at 250m patch scale and amphibian abundance both at 250m and 1000m scale. Fallow lands affected only reptilian diversity at all spatial scales. Plantation affected amphibian at all scales but reptiles only at the landscape scale. Habitat heterogeneity regulated only amphibian diversity. These results highlight the fact that different patch and landscape-scale factors regulate the diversity of reptiles and amphibians differentially. Such scale-specific information will crucially inform future conservation action for the herpetofauna in the agricultural landscape.     

肇庆市区道路绿化带植物景观评价研究

采用描述因子法,选择若干对道路植物景观效果贡献较大的指标,建立了整体指标评价体系。采用景观综合评价指数法模型,通过对指标的量化,对肇庆市道路植物景观进行了评价与分析。结果表明,肇庆市道路植物景观整体建设水平较好,55%的道路植物景观评价结果在Ⅱ级以上,仅有5%的道路在Ⅳ级以下。在所评价的8个因子中得分最高的是观赏时序,其次是观赏特性,这与所选的树种有很大关系;得分最低的是物种多样性,这与城市道路植物景观的高度人工化有关。针对评价结果提出了植物景观要从生态的可持续发展上体现它的价值、因地制宜地增加植物多样性及建立科学的绿地系统管理机制等建议。     

道路建设对西南地区景观格局的影响

为揭示西南地区道路建设对景观格局的影响,基于2015年土地覆被和道路数据,计算了研究区道路核密度与景观指数,在此基础上分析了道路建设的直接、间接和综合影响,探讨了影响的空间异质性和对不同土地覆被影响的特点,指出了各景观指数的适用性。结果表明：(1)道路建设使斑块密度增加,斑块离散化加剧,发生明显的破碎化趋势,同时道路核密度与PD、SHDI、SPLIT变化百分比呈显著正相关,与COHESION、CONTAG、PAFRAC呈显著负相关;(2)道路建设对景观指数的影响程度由大到小依次表现在：破碎化、斑块空间分布形态、聚集连通性,其中PD能很好的表征道路建设对景观破碎化的作用程度,SPLIT在识别破碎化程度高的区域更具优势;(3)不同景观指数具有不同适用性,PAFRAC适用于道路不发达区域,CONTAG适用于道路分布异质性较高的区域,DIVISION适用于人类活动强度不大的区域,COHESION、SPLIT适用于探究道路及伴随的人类活动共同作用的区域,PD、SHDI在探究道路的直接作用时适用性广泛;(4)探究不同土地覆被类型受道路建设的影响,林地优先选取PD、DIVISION;草地优先选取DI...     

Variation of group size among African buffalo herds in a forest-savanna mosaic landscape

Documenting within species group size variation is important to completely understand social organization within species and to interpret variation among species. Here, I investigated group size of African buffalo Syncerus caffer over 2 years in a heterogeneous landscape. African buffalo use closed continuous forest and vast open savannas, and anecdotal observations suggest that habitat type influences their social structure. While the Cape buffalo Syncerus caffer caffer is well studied, few data exist for the forest-dwelling Syncerus caffer nanus . I observed forest buffalo at Lopé National Park, Gabon, and examined variation of group size. Eighteen forest buffalo herds used the study area with an estimated population of 342 individuals (∼5 buffalo km⁻²). The mean group size for the 18 herds was 12 ± 2 (range of means=3–24), considerably smaller than Cape buffalo herds. For eight radiocollared forest buffalo, the mean group size was stable, varying little with time of day, across seasons, or between savanna and marsh habitat. However, herd size varied widely across herds, from fewer than 10 individuals in the smallest herds to more than 20 buffalo in the largest. Large herd size is associated with home ranges that contain substantial areas of open habitat, and thus more food resources than forested habitats.     

Assessing road effects on bats: the role of landscape, road features, and bat activity on road-kills

Recent studies suggest that roads can significantly impact bat populations. Though bats are one of the most threatened groups of European vertebrates, studies aiming to quantify bat mortality and determine the main factors driving it remain scarce. Between March 16 and October 31 of 2009, we surveyed road-killed bats daily along a 51-km-long transect that incorporates different types of roads in southern Portugal. We found 154 road-killed bats of 11 species. The two most common species in the study area, Pipistrellus kuhlii and P. pygmaeus, were also the most commonly identified road-kill, representing 72 % of the total specimens collected. About two-thirds of the total mortality occurred between mid July and late September, peaking in the second half of August. We also recorded casualties of threatened and rare species, including Miniopterus schreibersii, Rhinolophus ferrumequinum, R. hipposideros, Barbastella barbastellus, and Nyctalus leisleri. These species were found mostly in early autumn, corresponding to the mating and swarming periods. Landscape features were the most important variable subset for explaining bat casualties. Road stretches crossing or in the vicinity of high-quality habitats for bats—including dense Mediterranean woodland (“montado”) areas, water courses with riparian gallery, and water reservoirs—yielded a significantly higher number of casualties. Additionally, more road-killed bats were recorded on high-traffic road stretches with viaducts, in areas of higher bat activity and near known roosts.     

Responses of ground living arthropods to landscape contrast and context in a forest-grassland mosaic

Landscape context and contrast are major features of transformed landscapes. These concepts are largely described in terms of vegetation and land use, and are rarely used on how other biodiversity responds to these anthropogenic boundaries. South African grassland matrix is naturally dotted with indigenous forest patches which have recently been transformed with plantations of non-native species. We investigate how various arthropod groups (detritivores, predators, ants) respond to juxtaposition of pines, natural forests and grasslands. We assess landscape context effects between natural forests and pines by determining how species that commonly occur in the interiors of these habitats use the adjacent habitat, and how landscape contrast between natural forests and grassland affects these groups proportionately. We sampled arthropods using pitfall traps and active searches in transects running from natural forest interiors across the edge into the matrix interior (grassland or pines). Natural forests had higher predator and detritivore diversity, while grassland had greater ant diversity. Results highlighted the complementarity of natural forests and grassland for arthropod diversity. Higher beta-diversity was recorded across landscape contrast than landscape context. Pine and natural forest associated species overlapped into adjacent habitats indicating that pines are used by certain natural forest species. However, pines are not true natural forest extensions, with only some species being supported. Pines may be connecting naturally isolated arthropod populations, which could have important evolutionary consequences. Only through appreciation of a range of arthropod groups and their response to context and contrast across the whole landscape can we undertake meaningful biodiversity conservation.     

Foraging in a landscape mosaic: selection for energy and minerals in free-ranging cattle

Several studies have indicated the potential importance of nutrients, other than energy, in determining foraging decisions. A model was developed to test this idea, on the assumption of an intake maximization for different nutrients (energy, sodium and phosphorus). The model predictions were tested using field data from cattle grazing in a landscape mosaic of Pleistocene cover-sand and riverine grassland. Observations on foraging behaviour, food intake and diet composition were collected in thirteen 4-day-periods over 2 years. Habitat selection was determined by comparing the proportion of grazing time in different vegetation units with the available area proportion of the units. Two levels of habitat selection were examined: a micro-level (fine-scale, where vegetation units were considered separately) and a macro-level (coarse-scale, where vegetation units were combined to give selection at the landscape level). At the micro-level of habitat selection, no selection was apparent between the vegetation units of the riverine landscape, but the Deschampsia flexuosa unit was significantly selected for in the cover-sand landscape. At the landscape (macro-) level, the animals preferred the riverine landscape. The model revealed poor predictions of habitat occupancy on a micro-level. A much better prediction was obtained when vegetation units were combined at a macro-level. The D. flexuosa unit provided a higher energy intake, whereas the intake of sodium was higher in riverine grassland. Phosphorus proved relatively significant in determining habitat occupancy. Based on energy maximization alone, the model was a very poor predictor of habitat occupancy. It is argued that selection occurred mainly at the macro-level. The incorporation of different nutrient constraints in foraging models can then prove fruitful when seeking explanations of habitat occupancy. At the micro-level, difficulties for the animal in assessing nutrient availability may result in a less selective foraging pattern. However, the costs of increased selectivity may be greater than the benefits.     

Patterns of otter Lutra lutra road mortality in a landscape abundant in lakes

In order to reduce otter (Lutra lutra) road mortality and to predict accident sites, we assessed the localities of traffic accidents involving otters in the Uckermark County, Brandenburg, Northeast Germany. Eighty-eight otter accident sites from the years 1990 to 2003—as recorded by the Naturschutzstation Zippelsförde des Landesumweltamtes Brandenburg (Brandenburg State Office for Environment)—were categorised according to traffic and road patterns, otter habitat suitability, as well as presence and type of watercourse crossings. From these numerical data, we compiled a list of characteristics to identify other potentially dangerous sites where otter road traffic accidents are likely to occur using a geographic information system. With a principal component analysis, we categorised three groups of accident sites. Firstly, most otter road accidents were located close to either one or two lakes. Secondly, otters were frequently killed at places where no body of water occurred within a distance of 200 m to the road. Thirdly, and in contrast to other locations, in the Uckermark County, fewest accidents happened where a road crossed a watercourse. Mitigation measures were suggested and discussed for the recorded and potential accident sites.

     

Simulating viability of a spadefoot toad Pelobates fuscus metapopulation in a landscape fragmented by a road

A stochastic simulation model allowing for demographic and environmental stochasticity was developed in order to predict the dynamics of a Pelobates fuscus metapopulation. The metapopulation (consisting of ca 1000 adult individuals) was intensively studied in the field for a period of four years and the simulation model was parameterised (sex ratio, age‐specific survival rates, fecundity and dispersal between subpopulations) using field data. A sensitivity analysis revealed that a change in the juvenile yearly survival rate has a relatively larger effect on subpopulation persistence than adult survival rate and fecundity rate have. The probability of subpopulation persistence for one hundred years increased from 0 to 0.6 with a change in juvenile yearly survival rate from 0.35 to 0.40. Varying dispersal rate (from 0 to 1% of the individuals in a subpopulation moving to another subpopulation within a year) showed that four of the five subpopulations are dependent on the last one for persistence, indicating a source‐sink structure of the metapopulation. The subpopulation with the highest estimated juvenile survival has a far higher persistence probability than the others; they in turn would go extinct were it not for the occasional input of individuals from the source subpopulation. The source‐sink structure was also apparent when simulating the isolation effect of the road: persistence of the subpopulation isolated by the road decreases markedly with only a 20% decrease in the number of individuals dispersing to this pond. Environmental stochasticity decreases persistence time of the source subpopulation, but increases persistence time of the unstable ones. This is probably due to the presence of overcompensating density‐dependent factors affecting the subpopulations and to the more general effect of stochasticity: it may temporarily change reproduction and mortality rates, increase time to extinction for unstable subpopulations through a rescue effect; and decrease time to extinction for the more stable subpopulations.     

Effects of habitat transitions on rainforest bird communities across an anthropogenic landscape mosaic

We compared bird community responses to the habitat transitions of rainforest‐to‐pasture conversion, consequent habitat fragmentation, and post‐agricultural regeneration, across a landscape mosaic of about 600 km² in the eastern Australian subtropics. Birds were surveyed in seven habitats: continuous mature rainforest; two size classes of mature rainforest fragment (4–21 ha and 1–3 ha); regrowth forest patches dominated by a non‐native tree (2–20 ha, 30–50 years old); two types of isolated mature trees in pasture; and treeless pasture, with six sites per habitat. We compared the avifauna among habitats and among sites, at the levels of species, functional guilds, and community‐wide. Community‐wide species richness and abundance of birds in pasture sites were about one‐fifth and one‐third, respectively, of their values in mature rainforest (irrespective of patch size). Many measured attributes changed progressively across a gradient of increased habitat simplification. Rainforest specialists became less common and less diverse with decreased habitat patch size and vegetation maturity. However, even rainforest fragments of 1–3 ha supported about half of these species. Forest generalist species were largely insensitive to patch size and successional stage. Few species reached their greatest abundance in either small rainforest fragments or regrowth. All pastures were dominated by bird species whose typical native habitats were grassland, wetland, and open eucalypt forest, while pasture trees modestly enhanced local bird communities. Overall, even small scattered patches of mature and regrowth forest contributed substantial bird diversity to local landscapes. Therefore, maximizing the aggregate rainforest area is a useful regional conservation strategy.