Substrate preferences of coexisting invasive amphipods, <Emphasis Type="Italic">Dikerogammarus villosus</Emphasis> and <Emphasis Type="Italic">Dikerogammarus haemobaphes</Emphasis>, under field and laboratory conditions

Two Ponto-Caspian amphipods, Dikerogammarus villosus and Dikerogammarus haemobaphes, have expanded their geographical ranges from eastern Europe into Great Britain in recent years. This study represents one of the first examining the distribution and habitat preferences of coexisting populations of D. haemobaphes and D. villosus via field and laboratory experiments in the UK. Field surveys of a recently invaded lowland reservoir in the UK are complimented with ex situ laboratory mesocosm experiments examining the substrate preferences of coexisting populations of D. villosus and D. haemobaphes. Results from the field study indicated that D. haemobaphes dominated the macroinvertebrate community within the reservoir and demonstrated a strong affinity for large cobble and artificial substrates. D. villosus occurred at lower abundances but displayed a strong preference for coarse cobble substrates. A third invasive amphipod, Crangonyx pseudogracilis, was largely confined to sand/silt habitats. Laboratory mesocosm experiments clearly supported the field observations of D. villosus and D. haemobaphes with both species demonstrating a preference for cobble substrates. Results from the study highlight the importance of characterising physical habitat when investigating biological invasions and suggest that habitat availability may influence the extent and speed at which range expansion of new amphipod invaders occurs.     

Occupancy modeling of <Emphasis Type="Italic">Parnassius clodius</Emphasis> butterfly populations in Grand Teton National Park,Wyoming

Estimating occupancy patterns and identifying vegetation characteristics that influence the presence of butterfly species are essential approaches needed for determining how habitat changes may affect butterfly populations in the future. The montane butterfly species, Parnassius clodius, was investigated to identify patterns of occupancy relating to habitat variables in Grand Teton National Park and Bridger-Teton National Forest, Wyoming, United States. A series of presence–absence surveys were conducted in 2013 in 41 mesic to xeric montane meadows that were considered suitable habitat for P. clodius during their flight season (June–July) to estimate occupancy (ψ) and detection probability (p). According to the null constant parameter model, P. clodius had high occupancy of ψ?=?0.78?±?0.07 SE and detection probability of p?=?0.75?±?0.04 SE. In models testing covariates, the most important habitat indicator for the occupancy of P. clodius was a strong negative association with big sagebrush (Artemisia tridentata; β = ??21.39?±?21.10 SE) and lupine (Lupinus spp.; β?=???20.03?±?21.24 SE). While P. clodius was found at a high proportion of meadows surveyed, the presence of A. tridentata may limit their distribution within montane meadows at a landscape scale because A. tridentata dominates a large percentage of the montane meadows in our study area. Future climate scenarios predicted for high elevations globally could cause habitat shifts and put populations of P. clodius and similar non-migratory butterfly populations at risk.     

Impacts of Host Trees and Sowing Conditions on Germination Success and a Simple Ex Situ Approach to Generate Symbiotic Seedlings of a Rare Epiphytic Orchid Endemic to Hainan Island,China

For species relying on seeds for population regeneration, knowledge on seed germination behaviors in relation to environmental factors is critical in designing species recovery strategy. Dendrobium sinense is an orchid endemic to Hainan Island of China and listed as Endangered by the IUCN Redlist. It reproduces primarily via seeds in its natural habitat. However, how germination is impacted by major environmental factors is poorly known. This study aimed to examine germination success of D. sinense seeds using two approaches, i.e. in situ and ex situ, using host tree barks as germination media. The latter was intended to generate symbiotic seedlings in a simple and economic approach which could be used for reintroduction efforts. In addition, three factors of in situ symbiotic seed germination success, including different sowing time, location (distance from an adult plant), and host tree were investigated. Our results showed that seeds sown ex situ and in situ in July had the highest rates of germination. Seed germination was significantly higher ex situ using bark as medium than in situ. Seeds sown directly on Rhododendron moulmainense, the most common host tree, with naturally occurring conspecific orchids had the highest rate of germination. In contrast, ex situ seeds sown on the bark of Cyclobalanopsis blakeii, a non-host species, had the highest rate of seed germination. In situ a positive correlation was found between the seed germination rate and the distance of the seeds from the adult D. sinense. Based on these results, it is likely seedling recruitments are determined by host tree species, the presence of and the distance from an adult conspecific orchid, which imply the importance of the mycorrhizal fungi, which were not reported here. This study provided important information on the optimal environmental conditions for population augmentation and reintroduction, which can be used as part of the species recovery strategy.     

Prospects for improved off-crop habitat management for pollen beetle control in oilseed rape

There is an urgent need to develop sustainable and environmentally benign integrated pest management (IPM) strategies for arable crops. The enhancement and manipulation of naturally occurring populations of the natural enemies of crop pests through habitat management for ‘conservation biological control’, as well as habitat management to manipulate populations of the pests themselves, have the potential to become major components of successful IPM strategies. We review the studies that have contributed to our current understanding of how the crop margin, local landscape, and regional landscape can influence pollen beetle Brassicogethes aeneus (syn. Meligethes aeneus) (Coleoptera: Nitidulidae) abundance and damage to oilseed rape crops (Brassica napus), and the efficacy of their natural enemies. We also discuss how habitat management across these multiple scales may improve pollen beetle control, reducing the need for insecticide use and contributing towards sustainable production of this important crop which is grown on increasing areas for both food and fuel.     

Geographic distribution,habitat characterization,and conservation status of <Emphasis Type="Italic">Bolboschoenus</Emphasis> bulrushes (Cyperaceae) in the Hudson River Estuary,USA

Bulrushes of the genus Bolboschoenus are robust, ecologically important sedges occurring in wetlands, including intertidal marshes and mudflats. Despite their importance and multiple serious threats to their habitats, estuarine Bolboschoenus species remain poorly known. We conducted herbarium and field research in order to document historic and current geographic distributions, characterize the habitats, and assess the conservation status of Bolboschoenus species in the Hudson River Estuary, New York, U.S.A. Three species of Bolboschoenus grow in intertidal zones in the Hudson Estuary. Bolboschoenus fluviatilis occurs in the northern, upstream, and freshwater portion of the estuary with multi-year mean surface salinities of 0.078–2.0 ppt. Bolboschoenus robustus occupies the southernmost, downstream, and brackish to saline portion of the estuary with salinities of 4.9–16 ppt. Bolboschoenus novae-angliae occurs in the slightly to strongly brackish region between the other two species with salinities of 1.8–8.0 ppt. The geographic ranges of B. fluviatilis and B. robustus do not overlap, but B. novae-angliae has short zones of sympatry with each of the other two species. Syntopy of B. novae-angliae with each of the other two species is rare. In the Hudson Estuary, B. fluviatilis is secure, but B. novae-angliae and B. robustus are critically imperiled. Threats to future survival of Bolboschoenus species in the Hudson Estuary include competition from invasive plant species (especially Phragmites australis), eutrophication resulting from excess nutrient pollution, and habitat destruction. Our data and analyses provide critical new information for management of existing environmental problems and planned habitat restoration efforts in the Hudson River Estuary.     

Forest Type Influences Population Densities of Nocturnal Lemurs in Manompana,Northeastern Madagascar

Forest loss, fragmentation, and anthropization threaten the survival of forest species all over the world. Shifting agriculture is one of these threatening processes in Madagascar. However, when its cycle is halted and the land is left to regenerate, the resulting growth of secondary forest may provide a viable habitat for folivorous and omnivorous lemur species. We aimed to identify the response of nocturnal lemurs to different successional stages of regenerating secondary, degraded mature, and mature forest across a mosaic-type landscape. We surveyed four nocturnal lemur species (Avahi laniger, Microcebus cf. simmonsi, Allocebus trichotis, and Daubentonia madagascariensis) in four forest types of varying habitat disturbance in northeastern Madagascar. We estimated densities in mature and regenerating secondary forest for the eastern woolly lemur (Avahi laniger) and mouse lemur (Microcebus cf. simmonsi), two sympatric species with folivorous and omnivorous diets respectively. We did not estimate densities of Allocebus trichotis and Daubentonia madagascariensis owing to small sample size; however, we observed both species exclusively in mature forest. We found higher population densities of A. laniger and M. cf. simmonsi in secondary than in mature forest, showing the potential of regenerating secondary forest for lemur conservation. Several environmental factors influenced the detectability of the two lemur species. While observer and habitat type influenced detection of the eastern woolly lemur, canopy height and vine density influenced detection of mouse lemurs. Understanding how different species with different diets interact with anthropogenically impacted habitat will aid future management decisions for the conservation of primate species.     

African Cycad Ecology,Ethnobotany and Conservation: A Synthesis

Africa hosts a rich assemblage of cycads: 66 Encephalartos species, Stangeria eriopus and Cycas thouarsii. Most Encephalartos and S. eriopus adults appear to be fire-tolerant, and certain Encephalartos species may be fire-dependent. Four Encephalartos species and S. eriopus are primarily insect-pollinated. African cycad populations typically have sex ratios of 1:1, with very small populations often male-biased. Coning is typically infrequent and erratic, with many species exhibiting mast-seeding. Viable seed production in Encephalartos populations tends to decline with decreasing population size, and seed predation by weevils is common. Seed dispersal in Encephalartos is usually localized, but vertebrates may facilitate dispersal over longer distances. Stem material of 25 Encephalartos species and S. eriopus is used for traditional medicine, primarily in South Africa. Two-thirds of Africa’s cycad species are threatened, with four species already Extinct in the Wild. The illegal acquisition of cycads from wild populations is the principle threat to their persistence. Further research is recommended on seed and fire ecology, population dynamics, and the outcomes of conservation interventions.     

Archaeobotanical analysis of radiocarbon-dated plant remains with special attention to <Emphasis Type="Italic">Secale cereale</Emphasis> (rye) cultivation at the medieval village of Mankby in Espoo (Finland)

Several urban medieval sites in Finland (ad 1000–1500) have been archaeobotanically investigated, but until now only a few rural medieval settlements have been studied. Therefore, many aspects of the crops and agricultural methods of medieval villages in Finland still remain unknown. At the 12th to mid-16th century medieval village of Mankby, Espoo, a systematic sampling for archaeobotanical material was carried out. The analysed samples derived from hearths, building contexts and medieval field layers etc. The archaeobotanical material was carbonised, and it consisted mostly of conifer needles, cereal grains and weed seeds. Secale cereale (rye) and Hordeum vulgare (barley) were the only crop species found, Secale being the most frequent. Seeds of Bromus secalinus (rye brome) and achenes of Centaurea cyanus (cornflower), which are associated with autumn sown winter cereal crops, were also present. The archaeobotanical material shows areas of activity linked to storing crops, as well as cultivation within the village boundaries. Based on radiocarbon dated grains, cultivation of the fields started in the 12th century and continued until the abandonment of the village in 1556. Archaeobotanical material from Mankby has been compared to other contemporary sites in Finland, and differences between the sites can be seen. Results from Mankby have added to our knowledge of medieval agriculture, past areas of activity and economic conditions within the village.     

Population size and land use affect the genetic variation and performance of the endangered plant species <Emphasis Type="Italic">Dianthus seguieri</Emphasis> ssp. <Emphasis Type="Italic">glaber</Emphasis>

Human activity and land use changes in the past decades have led to landscape homogenization and small-scale fragmentation of grassland habitats in most regions of central Europe. As a result, populations of many grassland species are small and strongly fragmented, facing extinction due to genetic depauperation and local maladaptation in remnant habitats. In this study, remaining populations of the strongly endangered grassland species Dianthus seguieri ssp. glaber (“Ragged Pink”) in Bavaria were investigated in order to evaluate the environmental factors influencing its genetic variation and performance. We first evaluated habitat, vegetation and population structure. Species performance was then studied by assessing the number of generative shoots, flowers and fertile capsules; and evaluating seed weight and seed viability. Finally, genetic variation was analyzed using molecular markers (AFLPs). Our analyses revealed that population size and land use abandonment have the strongest impact on genetic variation and species’ performance. Large and extended populations were most variable. 72 % of overall genetic variability of Dianthus seguieri ssp. glaber was found to be within populations, whereas 28 % remained between populations. Increased vegetation height and coverage, and a high proportion of gramineous species resulting from the lack of land use, reduced genetic variation, effective fruit and seed set. Our study shows that both population size and land use abandonment need to be considered to ensure the long term protection of endangered plant species. Maintaining an open habitat structure and adequate soil nutrient conditions through targeted annual mowing regime, over-storey vegetation trimming and green waste removal and the establishment of vegetation buffer strips will allow this species’ persistence and continuous recruitment.     

Post-breeding densities,population sizes and lake size partitioning of loon species in western Chukotka,Russia

Loons (family Gaviidae) breed in small ponds and lakes across Arctic landscapes and are high level predators in the lake ecosystems. As such, they may serve as sentinel species, warning humans of alterations in habitat and ecosystem integrity in a region that is undergoing vast change due to climate warming. Here, we characterized the abundance and habitat use of four arctic breeding species of loons in the plains and surrounding mountains of western Chukotka, Russia. Loon surveys were conducted on foot and by boat from 2009–2015. Loon species differed in their use of the four lacustrine habitat types within the study area. In yedoma habitat, the yellow-billed loon (Gavia. adamsii) was the most abundant (0.593 birds/km²); on fluvial plain habitat, Pacific loons (G. pacifica) outnumbered other loons (0.701 birds/km²); mountain valleys were inhabited similarly by pacifica (0.354 birds/km²) and red-throated loons (G.stellata; 0.307); and maritime tundra was used only by pacifica (1.13) and Arctic loons (G. arctica; 0.553). G. adamsii was not observed in mountain valleys or maritime tundra. Mountainous portions of rivers were predominantly occupied by stellata and pacifica, and lowland rivers by stellata, pacifica and arctica. There was a significant difference in the size of lakes occupied by the four congeners. The largest loon, adamsii, occupied the largest lakes (0.69 km²), 80% larger than lakes utilized by pacifica (0.39 km²) and arctica (0.38 km²), and 35 times larger than stellata (0.02 km²). Most lakes were occupied by a single loon species (125/162, 77.2%).     

Water sources and water-use efficiency of desert plants in different habitats in Dunhuang,NW China

To understand habitat associated differences in desert plant water-use patterns, water stable oxygen isotope composition was used to determine water source and leaf carbon isotope composition (δ ¹³C) was used to estimate long-term water-use efficiency in three typical habitats (saline land, sandy land and Gobi) in Dunhuang. The primary findings are: (1) in the three habitats, plant species used mainly deep soil water (>120 cm), except for Kalidium foliatum in the saline land, which relied primarily on 0–40 cm soil water; (2) in the saline land and Gobi habitat, Alhagi sparsifolia had the most negative foliar δ ¹³C; in the sandy land, Elaeagnus angustifolia leaf was enriched in ¹³C than the other three species in 2011, but no species differences in foliar δ ¹³C was observed among the four species in 2012; (3) common species (Tamarix ramosissima and A. sparsifolia) may alter their water sources to cope with habitat differences associated changes in soil water availability with deeper water sources were used in the Gobi habitat with lower soil water content (SWC) compared to in the saline land and sandy land; (4) we detected significant habitat differences in foliar δ ¹³C in A. sparsifolia which may have resulted from differences in SWC and soil electrical conductivity. However, no habitat differences in foliar δ ¹³C were observed in T. ramosissima, which may attribute to the strong genetic control in T. ramosissima or the ability to access stable deep soil water. Overall, the results suggest that extremely arid climate, root distribution and soil properties worked together to determine plant water uptake in Dunhuang area.     

Genetic Differentiation and Demographic History of the Northern Rufous Mouse Lemur (<Emphasis Type="Italic">Microcebus tavaratra</Emphasis>) Across a Fragmented Landscape in Northern Madagascar

Phylogeographic barriers, together with habitat loss and fragmentation, contribute to the evolution of a species’ genetic diversity by limiting gene flow and increasing genetic differentiation among populations. Changes in connectivity can thus affect the genetic diversity of populations, which may influence the evolutionary potential of species and the survival of populations in the long term. We studied the genetic diversity of the little known Northern rufous mouse lemur (Microcebus tavaratra), endemic to Northern Madagascar. We focused on the population of M. tavaratra in the Loky–Manambato region, Northern Madagascar, a region delimited by two permanent rivers and characterized by a mosaic of fragmented forests. We genotyped 148 individuals at three mitochondrial loci (D-loop, cytb, and cox2) in all the major forests of the study region. Our analyses suggest that M. tavaratra holds average genetic diversity when compared to other mouse lemur species, and we identified two to four genetic clusters in the study region, a pattern similar to that observed in another lemur endemic to the region (Propithecus tattersalli). The main cluster involved samples from the two mountain forests in the study region, which were connected until recently. However, the river crossing the study region does not appear to be a strict barrier to gene flow in M. tavaratra. Finally, the inferred demographic history of M. tavaratra suggests no detectable departure from stationarity over the last millennia. Comparisons with codistributed species (P. tattersalli and two endemic rodents, Eliurus spp.) suggest both differences and similarities in the genetic clusters identified (i.e., barriers to species dispersal) and in the inferred demographic history. These comparisons suggest that studies of codistributed species are important to understand the effects of landscape features on species and to reconstruct the history of habitat changes in a region.     

Spatial genetic structure in seed stands of <Emphasis Type="Italic">Pinus lumholtzii</Emphasis> B.L. Rob. &amp; Fernald in Durango,Mexico

Sad pine is one of the most prominent pine species in Mexico due to its conspicuous pendulous foliage and extreme habitat. However, scientific studies of the species are scarce, and genetic information on sad pine populations is lacking. This endemic tree species occurs naturally on the Sierra Madre Occidental where it covers a total area of about 1,600,000 ha. It typically grows with several species of Quercus and Pinus or in pure stands in uneven-aged forests. Pinus lumholtzii is naturally spatially fragmented, and genetic research on seed and pollen dispersal patterns and spatial genetic structure (SGS)—and the possible implications of these in terms of evolution, conservation and breeding management—is particularly important. Given the fragmented occurrence of the preferred soil type, the goal of this research was to use amplified fragment length polymorphism (AFLP) markers to identify potential differences in spatial genetic structure within and between five P. lumholtzii seed stands at fine and large scales. At the fine scale, we almost always observed non-significant autocorrelation, suggesting that the genetic variants of P. lumholtzii are randomly distributed in space within each sampled seed stand. At the larger scale, our findings provide strong support for the theory of isolation by distance that predicts the expected pattern of SGS at drift–dispersal equilibrium. We recommend a network of P. lumholtzii seed stands of maximum distances of 100 km among stands to prevent greater loss of local genetic variants and use the seeds for reforestations in a radius of maximal 50 km from their proveniences.     

Associations between stream habitat characteristics and native and alien crayfish occurrence

Human mediated introductions of non-indigenous crayfish species (NICS) are responsible for their rapid colonisation of European freshwaters. The introduction of North American crayfish is furthermore linked to the spread of crayfish plague and the decline of indigenous crayfish species (ICS). As the management of ICS and NICS have become necessary, a detailed knowledge on their distribution and ecological requirements is needed. We studied the current range of native noble crayfish Astacus astacus and stone crayfish Austropotamobius torrentium, as well as alien signal crayfish Pacifastacus leniusculus in Carinthia (Austria) and evaluated environmental and physical habitat features in streams with and without crayfish. Meanwhile, the loss of many ICS populations was recorded and alien P. leniusculus was found to be widespread in this region. Most of the habitat features of streams having crayfish differed significantly from sites lacking crayfish for at least one investigated native or alien species. Furthermore, multivariate and regression analyses showed specific differences in the habitat use of the investigated crayfish. Our results showed that the presence of alien P. leniusculus was associated with larger and smoother sloped lowland rivers, while the occurrence of the two native species was confined to smaller streams either at higher altitudes and with distinct physical habitat conditions (A. torrentium) or with moderate water temperatures (A. astacus). This study helps to identify potential refuge areas for the endangered native species and to predict the further spread of the most common non-native crayfish species in European streams.     

Assessment of Habitat Fragmentation and Corridors for an Isolated Subspecies of the Sichuan Golden Snub-Nosed Monkey, <Emphasis Type="Italic">Rhinopithecus roxellana hubeiensis</Emphasis>

Understanding habitat quality and landscape connectivity and exploring corridors connecting habitat patches are crucial for conservation, particularly for species distributed among isolated populations. The Sichuan golden snub-nosed monkey, Rhinopithecus roxellana, is an Endangered primate species endemic to mountainous forests in China. Its easternmost distribution lies in the Shennongjia area, which harbors an isolated subspecies, R. roxellana hubeiensis. Unfortunately, it has experienced significant habitat loss, fragmentation, and dramatic population decline in recent decades, primarily due to increased human disturbance. To quantify habitat quality, identify suitable habitat patches, and detect possible linkages among these patches for R. roxellana hubeiensis, we conducted habitat suitability assessments and landscape connectivity analyses in the Shennongjia area based on a set of environmental factors. We created a habitat quality model and a movement cost surface for the Shennongjia area based on a habitat suitability index, graph theory, expert knowledge, field experience, and information from the literature. Our results show that suitable habitat for R. roxellana hubeiensis in Shennongjia is fragmented and limited, and that this is particularly true for highly suitable habitats. We detected six core habitat patches and six least-cost paths and corridors. Our study does not provide accurate distributions of the monkeys and their habitat use. However, it identifies the most feasible and traversable habitats and corridors, which should be conservation priorities for this subspecies, and provides valuable guidance for reevaluating habitat conservation plans.     

Effect of flower traits and hosts on the abundance of parasitoids in perennial multiple species wildflower strips sown within oilseed rape (<Emphasis Type="Italic">Brassica napus</Emphasis>) crops

Reducing the use of insecticides is an important issue for agriculture today. Sowing wildflower strips along field margins or within crops represents a promising tool to support natural enemy populations in agricultural landscapes and, thus, enhance conservation biological control. However, it is important to sow appropriate flower species that attract natural enemies efficiently. The presence of prey and hosts may also guide natural enemies to wildflower strips, potentially preventing them from migrating into adjacent crops. Here, we assessed how seven flower traits, along with the abundance of pollen beetles (Meligethes spp., Coleoptera: Nitidulidae) and true weevils (Ceutorhynchus spp., Coleoptera: Curculionidae), affect the density of parasitoids of these two coleopterans in wildflower strips sown in an oilseed rape field in Gembloux (Belgium). Only flower traits, not host (i.e. pollen beetles and true weevils) abundance, significantly affected the density of parasitoids. Flower colour, ultraviolet reflectance and nectar availability were the main drivers affecting parasitoids. These results demonstrate how parasitoids of oilseed rape pests react to flower cues under field conditions. Similar analyses on the pests and natural enemies of other crops are expected to help to develop perennial flower mixtures able to enhance biological control throughout a rotation system.     

Evaluating the local habitat history deepens the understanding of the extinction debt for endangered plant species in semi-natural grasslands

Habitat losses occur non-randomly within human-modified landscapes, resulting in high spatial heterogeneity of local habitat histories. Although local habitat history can modulate the existence of extinction debt (i.e., the number of populations predicted to become extinct) in a landscape, its role in detecting extinction debt has not been examined explicitly. We aimed to compare the detectability of extinction debt among populations of an endangered semi-natural grassland species, Echinops setifer (Compositae), in the grassland landscape of Mt. Aso, Japan. We classified populations into three groups that differed in local habitat history: stable (habitat loss ≤30% since the 1930s), moderately decreased (30% < loss ≤ 90%), and severely decreased (loss >90%). We then evaluated whether the effects of habitat areas during the 1930s and 2000s varied among groups to explain population size by GLMMs and estimated coefficient of explanatory variable by Bayesian MCMC methods. Within the groups, stable group showed significant positive relationships with both past and current habitat areas. The moderately decreased group only showed significant positive relationships with past habitat areas, indicating the existence of extinction debt in these populations. The severely decreased group only showed significant positive relationships with current habitat areas, indicating that they may have already paid their extinction debt because the rate of grassland loss exceeded the extinction threshold. Even within the same landscape, extinction debt varied in response to local habitat history. In spatially heterogeneous landscapes, evaluation of effects of local habitat history can elucidate the habitat-based extinction risks for plant populations.