Home range size scales to habitat amount and increasing fragmentation in a mobile woodland specialist

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Ultrastructure of the respiratory epithelium in the lungs of the tortoise,Testudo graeca

The respiratory epithelium in the lungs of the tortoise (Testudo graeca) has been studied by electron microscopy. The epithelium consists of a mosaic of two different cell types (here called "pneumonocytes"). Type I pneumonocytes are roughly squamous and possess attenuated flanges of cytoplasm which extend over the septal capillaries. Localized cytoplasmic expansions are often present near the periphery of these flanges. Most of the organelles are concentrated in the perinuclear region; the most prominent of these are the mitochondria and osmiophilic inclusions. In contrast, type II pneumonocytes are cuboidal and are richly endowed with organelles including large Golgi complexes, extensive endoplasmic reticulum and numerous inclusion bodies. The morphological evidence suggests that type I pneumonocytes are involved in the secretion of osmiophilic material (presumed to be pulmonary surfactant) and in maintaining the integrity of the air-blood barrier. Type II pneumonocytes appear to be concerned solely with the production of surfactant.     

The use of habitat mosaics by terrestrial vertebrate fauna: implications for conservation and management

Many species of vertebrates require multiple habitats to obtain different resources at different stages of their life-cycles. Use of habitat mosaics takes place on a variety of spatial and temporal scales, from a daily requirement for adjacent habitats to seasonal use of geographically separated environments. Mosaics of habitats are also required in some species to allow ontogenetic habitat shifts, while in others each sex may have specific requirements that are met by different habitats. The extent and nature of animal movements are key (but generally poorly known) factors affecting the vulnerability of species to landscape change. The requirement by many species for multiple habitats suggests that their conservation will be most effective in a mosaic environment and that protection of certain high profile habitats alone, such as rainforest, will be insufficient to achieve conservation goals. Management regimes that result in homogenization of habitats should be avoided. Priority should be given to research that identifies the extent to which species can locate habitat mosaics, at different spatial scales and arrangements, in modified environments.     

生境片断化对植物种群遗传结构的影响及植物遗传多样性保护

生境片断化是指大而连续的生境变成空间隔离的小种群的现象。生境片断化对植物种群遗传效应包括生境片断化过程中的取样效应及其后的小种群效应（遗传漂变、近交等）。理论研究表明,生境片断化后,植物种群的遗传变异程度将降低,而残留的小种群间的遗传分化程度将升高。然而对一些植物的研究表明,生境片断化对植物种群的遗传效应要受其他一些因素的影响,如世代长度、片断化时间、片断种群的大小、基因流的改变等。最后,针对生境     

水位波动对洞庭湖越冬小天鹅家域的影响

洞庭湖是小天鹅在我国的重要越冬地之一,为探讨洞庭湖水位变动对越冬小天鹅活动的影响,本研究于2014-2015年利用卫星跟踪技术对洞庭湖自然保护区18只越冬小天鹅活动轨迹进行跟踪,采用最小凸多边形（MCP）和核心密度估计（KDE）方法估算了越冬中、后期不同水位条件下小天鹅的家域。同时,基于MODIS遥感数据提取洞庭湖水体面积、计算水体淹没时间指数（STI）,进而开展了水位与家域关系、栖息地选择模式等方面的分析和探讨。结果表明：水位对小天鹅家域起制约作用,随着水位上升小天鹅家域范围会明显减小;越冬期间小天鹅喜好在空间相邻的浅水和草地综合性区域活动,食物资源分布和可获得性是小天鹅活动区发生改变的主要原因。     

Habitat Selection by the Spur-thighed Tortoise Testudo graeca in a Multisuccessional Landscape: Implications for Habitat Management

As a result of human activities, natural Mediterranean landscapes (including agro-ecosystems) are characterised by a mosaic-like structure with habitat-patches at different successional stages. These systems have high biodiversity levels and are home to a large number of species protected by European laws whose habitats should be adequately managed. In the present work, we study habitat use from an applied point of view in the spur-thighed tortoise Testudo graeca, an endangered reptile present in semi-arid Mediterranean agro-ecosystems. Results show that, at a landscape scale, the species selects simplified vegetation structures and includes in its home range re-colonisation shrubland and small non-irrigated fields. Within the home range, habitat selection patterns vary and areas with higher vegetation cover and complexity are selected. Detected patterns are discussed in terms of the ecological requirements of the species and with a hierarchical view of resources and conditions. The implications of our findings for habitat management aimed at the conservation of the species are also discussed.     

Predicting the distribution of a suitable habitat for the white stork in Southern Sweden: identifying priority areas for reintroduction and habitat restoration

The loss of wetlands and semi-natural grasslands throughout much of Europe has led to a historic decline of species associated with these habitats. The reinstatement of these habitats, however, requires spatially explicit predictions of the most suitable sites for restoration, to maximize the ecological benefit per unit effort. One species that demonstrates such declines is the white stork Ciconia ciconia , and the restoration of habitat for this flagship species is likely to benefit a suite of other wetland and grassland biota. Storks are also being reintroduced into southern Sweden and elsewhere, and the a priori identification of suitable sites for reintroduction will greatly improve the success of such programmes. Here a simple predictive habitat-use model was developed, where only a small but reliable presence-only dataset was available. The model is based on the extent and relative soil moisture of semi-natural pastures, the extent of wetlands and the extent of hayfields in southern Sweden. Here the model was used to predict the current extent of stork habitat that is suitable for successful breeding, and the extent of habitat that would become suitable with moderate habitat restoration. The habitat model identifies all 10 occupied nesting sites where breeding is currently successful. It also identifies ∼300 km² of habitat that is predicted to be suitable stork habitat, but that is presently unused; these sites were identified as potential areas for stork reintroduction. The model also identifies over 100 areas where moderate habitat restoration is predicted to have a disproportionate effect (relative to the restoration effort) on the area of suitable habitat for storks; these sites were identified as priorities for habitat restoration. By identifying areas for reintroduction and restoration, such habitat suitability models have the potential to maximize the effectiveness of such conservation programmes.     

Home range,survival, and dispersal of endangered Saimaa ringed seal pups: Implications for conservation

Lake Saimaa in eastern Finland is inhabited by a critically endangered ringed seal subspecies Pusa hispida saimensis. Since accidental mortality in gill nets, resulting in reduced pup survival, is considered to be the main factor contributing to the decline in its population, fishing restriction areas have been established. In this study, 10 pups were located daily using very high frequency (VHF) telemetry to estimate their home ranges, movements, and survival. The pups dispersed after weaning at the age of ca. 3 mo and moved up to 15 km a day between consecutive locations and up to 25 km away from their birth sites. The home ranges of the pups at the age of 3–4 mo were variable in size, from 3 to 162 km². The pups preferred the same shallow water areas (<6 m) that were used for gill net fishing. The annual fishing restrictions covered an average of 83% of the pups’ home ranges. Four of the pups were nevertheless killed in fishing gear. The results have implications for Saimaa ringed seal management and conservation. For instance, large home ranges of pups and the long distances movements should be taken into account when zoning shore use and imposing fishing restrictions.     

Fragmented landscapes, habitat specificity, and conservation genetics of three lizards in Florida scrub

Dry, sandy scrub habitats of the Floridapeninsula represent naturally fragmentedremnants of xeric ecosystems that werewidespread during the Pliocene and earlyPleistocene. This habitat is characterized byhigh endemism, and distribution of genetic andevolutionary diversity among scrub ``islands' isof compelling interest because Florida scrub israpidly disappearing under human development. We compare range-wide diversity inmitochondrial cytochrome b sequences forthree scrub-associated lizards with contrastinglevels of habitat specificity. All speciesshow strong geographic partitioning of geneticdiversity, supporting the hypothesis that scrubfauna is highly restricted by vicariantseparations. The mole skink (Eumecesegregius), the least habitat specific, has thelowest phylogeographic structure among thelizards (_st = 0.631). The mtDNAgeneology for E. egregius is not entirelyconcordant with the five recognized subspeciesand supports a link between populations incentral Florida (E. e. lividus) and theFlorida Keys (E.e. egregius) rather thana previously proposed affiliation betweennorthern and southern populations. The Floridascrub lizard (Sceloporus woodi) is themost habitat specific of the lizards and hasthe strongest phylogeographic structure (_st = 0.876). The sand skink (Neosepsreynoldsi) falls between the moleskink and scrub lizard in terms of habitatspecificity and phylogeographic structure (_st = 0.667). For all three species,networks of mtDNA haplotypes coalesce on twocentral ridges that contain the oldest scrub. The geographic structure and deep evolutionarylineages observed in these species have strongimplications for conservation, includingstrategies for translocation, reserve design,and management of landscape connectivity.     

Molecular biodiversity in the moss <Emphasis Type="Italic">Leptodon smithii</Emphasis> (Neckeraceae) in relation to habitat disturbance and fragmentation

Bryophytes seem particularly suitable to investigate genetic diversity in relation to habitat disturbance due to their large employment as bioindicators and to the recent application of molecular markers to moss population studies. Genetic variation and structure were analysed in seven urban, extraurban and remote populations of Leptodon smithii, an epiphytic moss of Quercus ilex, a phanerogamic species of Mediterranean climax vegetation. A total of 210 individual shoots were DNA extracted and amplified with internal simple sequence repeat (ISSR) primers, and 54 haplotypes were identified. An uneven distribution of haplotype number and frequencies was observed among sites, with a higher number of haplotypes and more homogeneous haplotype frequencies in the extraurban/remote populations. Molecular diversity indices were overall higher in the extraurban sites than in the urban ones. Multilocus linkage disequilibrium values were in line with the occurrence of sexual/asexual reproduction in the seven populations. The isolation-by-distance model was not supported by Mantel test among sites; however, within-population fixation index (F_ST) highlighted a clear relation between genetic and physic distances among trees, suggesting a limited dispersal range for L. smithii’s spores. The genetic structure was mainly affected by population size, wood structure and extent, and genetic drift consequent to habitat fragmentation and human-induced disturbance.     

Effect of habitat complexity on biological control by the red imported fire ant (Hymenoptera: Formicidae) in collards

A potentially important and understudied biological control agent in US agroecosystems is the red imported fire ant, Solenopsis invicta Buren. Red imported fire ants may be particularly important biological control agents because we can manipulate their abundance with changes in habitat complexity. The effect of habitat complexity on biological control by fire ants was determined using plots of collards intercropped with white clover (complex habitat) and simple collard monocrops. The most economically significant pests of collards are larvae of the diamondback moth (DBM), Plutella xylostella (L.). Predation of DBM larvae by fire ants was more rapid and efficient in the intercrop than the monocrop. Red imported fire ants were 23% less abundant in the intercrop than the monocrop, however, suggesting that fire ants had a greater per capita effect on DBM survival in the complex habitat. Red imported fire ant predation of DBM larvae was significantly affected by larval density. Red imported fire ants also reduced the survival of leaf beetles, another economically significant pest taxa, by 45%. Furthermore, collard leaf damage tended to be inversely related to fire ant density and fire ants were more effective at reducing crop damage in the complex intercrop. Our study indicates the ability of red imported fire ants to be effective biological control agents and suggests that increasing habitat complexity can enhance red imported fire ant efficacy and herbivore control.     

An investigation of habitat occupancy by the nightingale Luscinia megarhynchos with respect to population change at the edge of its range in England

The nightingale Luscinia megarhynchos has undergone population decline and range contraction at the north-western limit of its distribution in England during the last 25 years. We examine patterns of habitat occupancy and habitat availability across sites with a range of population histories to see whether habitat loss is a plausible explanation for these declines. The number of singing males in 1999 correlated with area of primary nightingale habitat in the East Midlands (where the species has declined), but not in East Anglia (where the population has been stable). Change in population size between 1980 and 1999 and current habitat availability were weakly correlated in the East Midlands but not in East Anglia. These results are consistent with habitat loss having contributed to the decline of the nightingale in the East Midlands, but suggest that other, wider-scale, factors may be at least partially responsible for determining the abundance of the species within England as a whole.     

Bird community variation across <Emphasis Type="Italic">Polylepis</Emphasis> woodland fragments and matrix habitats: implications for biodiversity conservation within a high Andean landscape

The scattered and dwindling Polylepis woodlands of the high Andean global hotspot have been identified as being of particular importance to biodiversity conservation, and yet little is known of the make-up of their faunal communities, how these vary across landscapes, and how well species might tolerate matrix/edge habitats. We examined the bird communities and vegetation characteristics of Polylepis woodlands and the surrounding matrix habitats at three sites in the Cordillera Vilcanota, southern Perú (3,400–4,500 m). The vegetation structure of woodlands varied significantly across the three sites but all were dominated by two Polylepis tree species, with mossy ground cover. Matrix habitats were treeless and dominated by ground-level puna grass-steppe or boulder scree vegetation. Bird species richness and diversity, encounter rates and the number of globally-threatened and restricted-range bird species were consistently higher in the Polylepis forests, than in matrix habitat. We used canonical correspondence analysis (CCA) to identify habitat gradients across the landscape, and to classify bird species according to their association with Polylepis, the matrix or Polylepis-matrix interface. There were few matrix-restricted bird species, but around half the bird community, including fourteen threatened or restricted-range species, were Polylepis-dependant. Many of these species had very narrow niches. The Polylepis-matrix interface was dominated by species traditionally considered invasive ecological generalists. Our study illustrates the overriding importance of Polylepis interior habitats, indicating that conservation strategies for high Andean birds must focus on patch size maintenance/enlargement, enhancement of within-patch habitat quality, and efforts to safeguard connectivity of suitable habitat across what is essentially an inhospitable puna/scree matrix.