Breeding and post-breeding responses of woodland birds to modification of habitat structure by deer

Birds in woodland can be affected by increasing deer populations through changes to vegetation structure and potential impacts on foraging resources; these effects need to be better understood. Effects of deer browsing are reported from a replicated split-plot exclusion experiment in English coppiced woodland. All stages of growth were examined up to eight years after felling. We used standardised mist-netting (totaling 1920 h) to sample birds in breeding and post-breeding periods. Deer browsing strongly altered vegetation structure by reducing canopy cover and shrub layer foliage density. However deer did not affect invertebrate density per unit of foliage, providing no evidence of an ungulate-mediated plant chemical response affecting forage quality for invertebrate herbivores. At avian guild level, significantly more ground and understorey foraging birds were captured where deer were excluded, and negative responses to browsing were more marked for pooled migrants than pooled residents. At the species level, especially pronounced negative effects were evident for dunnock (Prunella modularis) and garden warbler (Sylvia borin); approximately five times more dunnocks were captured in deer exclosures than in browsed vegetation. We also detected negative responses to browsing by nightingale (Luscinia megarhynchos) and long-tailed tit (Aegithalos caudatus). No significant positive responses to browsing were detected. For some species the use of young re-growth increased post breeding relative to the breeding period, including a marked shift by pooled residents that involved a disproportionate number of juveniles. Previous studies in North America have shown that, through vegetation modification, ungulate activity can alter woodland bird assemblages; as far as we are aware this is the first experimental demonstration of effects in Europe, and at low to moderate browsing intensity typical of the wider landscape scale.     

Habitat use and conservation of bumblebees (Bombus spp.) under different grassland management regimes

Declines in the natural populations of several bumblebee species across Britain and Europe are an increasing cause for concern. In this study the habitat use of bumblebees was investigated on Salisbury Plain Training Area, the largest remaining area of unimproved chalk grassland in north-west Europe. Habitat characteristics influencing the overall abundance, species richness and foraging activity of bumblebees included the diversity and abundance of flowering plant species (particularly of favoured forage plants such as Trifolium pratense), vegetation structure and height. It is suggested that different Bombus species respond to these habitat characteristics depending on their specific foraging and nesting requirements, the case of Bombus humilis being especially relevant. The effects of several grassland management practices were considered in terms of their suitability for the conservation of bumblebee habitats. Cattle grazing was shown to be preferable to both sheep grazing and the absence of any management, although the timing and intensity of such grazing was important. Small-scale disturbances caused by vehicle activity were also of value in producing locally abundant forage resources in less intensively managed grasslands.     

Habitat fragmentation in an urban environment: large and small fragments support different arthropod assemblages

We investigated the effects of fragmentation due to urbanisation on the species composition and functional roles of ants, beetles, spiders, flies and wasps. The study was conducted in 21 fragments of heath and woodland in south-eastern Australia classed as either ‘small’ (? 4 km²) or ‘large’ (? 80 km²). Arthropods were pitfall-trapped and identified to family or genus and morphospecies and microhabitat characteristics were recorded. Large fragments did not support more species per unit area than small fragments for most arthropods, although there were more species of ants per sampling unit in small than large woodland fragments, mainly due to a higher frequency of generalist species in smaller fragments. Large and small habitat fragments contained different assemblages of spiders, wasps and ants, indicating that predators and parasitoids are affected more strongly than other trophic groups. Arthropod assemblages within larger fragments where grids were furthest apart were less similar than those within smaller fragments where grids were closer together in woodland, but not in heath. The responses of arthropods to fragmentation suggest that, in addition to effects of reduced area and proximity to the urban matrix, changes in fire regimes and the degradation of habitats resulting from urbanisation, may have a role in altering arthropod assemblages, particularly affecting those species belonging to higher trophic levels. Management goals for urban remnants should identify mechanisms for controlling fire and anthropogenic disturbance such that they closely resemble the levels of these factors in larger fragments.     

Phylogeography and conservation of the populations of Zootoca vivipara carniolica

The lizard Zootoca vivipara has both oviparous and viviparous populations which belong to distinct clades. This study aims to elucidate the geographic distribution, phylogeography and conservation priority of the oviparous subspecies, Zootoca vivipara carniolica, that has recently been identified in Slovenia. We studied seven Slovenian populations, two northeastern Italian populations and five northwestern Italian populations. The seven cytochrome b haplotypes that we identified from the Slovenian and Italian oviparous populations form a monophyletic basal clade. The high homogeneity of the Slovenian and northeastern Italian populations (nucleotide diversity π=0.06%) is a striking contrast with the pattern observed in northwest Italy where each of the five populations studied presents a private haplotype (π=1.03%). The results obtained suggest that all the extant lineages of Z. v. carniolica have originated in an Italian refuge. The reproductive and phylogenetic distinctiveness of Z. v. carniolica clearly justifies conservation of its populations, especially in Italy where the highest genetic diversity and the most ancestral haplotype were observed.     

Conservation of Pteropus livingstonii based on roost site habitat characteristics on Anjouan and Moheli, Comoros islands

Livingstone's fruit bats, Pteropus livingstonii, (Pteropodidae: Chiroptera) are endemic to only two islands, Moheli and Anjouan of the Comoros Islands in the West Indian Ocean. With an estimated population of less than 2000 individuals, P. livingstonii is listed as Critically Endangered on the International Union for the Conservation of Nature's Red List. Yet the habitat characteristics of these giant fruit bats, or flying foxes, are poorly known. I conducted field research during 5 months in 1998 focused on finding new roost sites, measuring characteristics of both roost sites and roost trees at new as well as previously identified roost sites, and recording the same characteristics for a set of absence sites. I identified six new roost sites allowing me to measure the characteristics of 15 known roost sites and seven absence sites. The study spanned both dry and rainy seasons and I found a significant increase in the number of individuals at roost sites during the rainy season. Bat roost sites were associated with presence of water, southeast aspect, steep slopes, and presence of several native tree species. Roost habitat was characterized based on biotic, abiotic and human factors. This research on habitat characteristics is contributing to the development of a conservation action plan for the Livingstone's fruit bats. However, further research on dry season roost sites and distribution as well as feeding sites is necessary in order to better understand their seasonal habitat requirements and therefore ensure the conservation of P. livingstonii.     

Negotiating China's rise: The dynamics of Chinese business associations and the Belt and Road Initiative in Brunei Darussalam

With an increasingly assertive China and the intensifying influence of the Sinocentre, Chinese overseas who have access to Chineseness can exercise their agentic power in using their cultural capital for economic gains. Beijing has recognised the potential for diasporic Chinese entrepreneurs to contribute to the Belt and Road Initiative (BRI) given their influence in Southeast Asia's economy. Correspondingly, these entrepreneurs hail the BRI as a strategic opportunity for them to turn their cultural capital into fiscal capital. Considering the increased global connectivity and new Chinese migration geographies led by the BRI, this article examines the case of Chinese business associations in Brunei Darussalam. The heterogenous responses of these ethnic Chinese and their associations to China and the BRI attest to the multiplicity and contestations of Chineseness based on different migration histories and sentiments to their ancestral land. We focus on the dynamics between the old Chinese Bruneian business elites and the more recent Chinese business migrants from Malaysia and China. An investigation of the cultural and economic politics within the Chinese Bruneian business community will provide insights into the modality of Chineseness as an economic asset that can be tactically used by diasporic Chinese entrepreneurs to maintain their social position and to respond to China's economic rise.     

Empirical assessment of water management institutions in northern China

We examine the development of irrigation management in northern China using data from village and household panels. During the past decade, reform-oriented institutions, such as water user associations and contracting, have largely replaced the traditional institution of collective management in village-level irrigation systems. A feature unique to China is that water user associations and contractors are provided with monetary incentives to save water. Water user associations have not yet achieved the broad-based participation of farmers that some advocates consider as a primary goal for forming the associations. Many village leaders serve also as the leaders of water user associations, thus possibly reducing opportunities for receiving operational input and policy direction from farmers. However, we observe improved performance of irrigation systems managed by water user associations, relative to collective management, in terms of maintenance expenditures, the timeliness of water deliveries, and the rates of fee collection. Performance has improved also in systems managed by contractors, although not as substantially as in the case of water user associations.     

胶结物质驱动的土壤团聚体形成过程与稳定机制

团聚体是土壤的基本组成单元,影响着土壤水、气、热及养分的保持和运移。胶结物质在团聚体形成过程中起关键作用,但不同类型胶结物质在土壤团聚体中所起作用与机理尚缺乏系统总结。本论文回顾了土壤团聚体相关的关键理论,梳理了不同地理环境与人为活动下土壤团聚体中胶结物质类型、形态、转化与作用机制,探讨了胶结物质对土壤团聚体结构与稳定性的影响,提出了胶结物质驱动的土壤团聚体自组织形成过程模型,阐明了土壤团聚体的形成与转化机制。最后对土壤团聚体研究领域未来的发展进行展望,特别是在土壤团聚体的原位分析方法、土壤团聚体形成过程的定量化描述、土壤团聚体稳定性在景观尺度上的空间结构、良好土壤结构体培育的产品与技术研发等方面还有待加强。这些工作的开展将对培育良好土壤团聚体、揭示土壤物质循环与演化过程、提高土壤质量和生产力等具有重要的科学意义和生产实践价值。     

The occurrence of primary burrowing crayfish in terrestrial habitat

A researcher’s perception of a target species’ landscape strongly influences the design of habitat studies conducted at broad spatial scales. Consequently, researcher-dependent perceptions may misguide conservation efforts. Although the life histories of some crayfish (i.e., primary burrowers) are centered on a fossorial existence independent of surface water, all North American crayfish are viewed in an aquatic context. This paradigm restricts the range of habitats that are typically sampled and managed for crayfish conservation. This study used presence/absence of the primary burrower Distocambarus crockeri at 137 locations within the Long Cane Ranger District of the Sumter National Forest, South Carolina, USA, to model the habitat association of the species across a GIS-based landscape. Logistic regression indicated that D. crockeri presence was most strongly associated with a terrestrial habitat defined by a set of morphologically similar soils located along ridge tops. Furthermore, the species was negatively associated with aquatic habitats such as streams and floodplains. The results indicate that D. crockeri is a terrestrial habitat specialist and should be modeled and managed at the landscape as a terrestrial organism. When viewed as a subset of the total United States cambarid fauna, primary burrowers are disproportionately imperiled. Primary burrowers comprise only 15% of the total crayfish fauna, while they account for 32% of those crayfish ranked critically imperiled. Habitat loss and an aquatic bias that restricted sampling to aquatic and semi-aquatic habitats might explain the group’s disproportionate imperilment.     

Herpetofauna diversity and microenvironment correlates across a pasture-edge-interior ecotone in tropical rainforest fragments in the Los Tuxtlas Biosphere Reserve of Veracruz, Mexico

We evaluated the relationship between amphibian and reptile diversity and microhabitat dynamics along pasture-edge-interior ecotones in a tropical rainforest in Veracruz, Mexico. To evaluate the main correlation patterns among microhabitat variables and species composition and richness, 14 ecotones were each divided into three habitats (pasture, forest edge and forest interior) with three transects per habitat, and sampled four times between June 2003 and May 2004 using equal day and night efforts. We measured 12 environmental variables describing the microclimate, vegetation structure, topography and distance to forest edge and streams.After sampling 126 transects (672 man-hours effort) we recorded 1256 amphibians belonging to 21 species (pasture: 12, edge: 14, and interior: 13 species), and 623 reptiles belonging to 33 species (pasture: 11, edge: 25, and interior: 22 species). There was a difference in species composition between pasture and both forest edge and interior habitats. A high correlation between distance to forest edge and temperature, understorey density, canopy cover, leaf litter cover, and leaf litter depth was found. There was also a strong relationship between the composition of amphibian and reptile ensembles and the measured environmental variables. The most important variables related to amphibian and reptile ensembles were canopy cover, understorey density, leaf litter cover and temperature.Based on amphibian and reptile affinity for the habitats along the ecotone, species were classified into five ensembles (generalist, pasture, forest, forest edge and forest interior species). We detected six species that could indicate good habitat quality of forest interior and their disappearance may be an indication of habitat degradation within a fragment, or that a fragment is not large enough to exclude edge effects. Different responses to spatial and environmental gradients and different degrees of tolerance to microclimatic changes indicated that each ensemble requires a different conservation strategy. We propose to maintain in the Los Tuxtlas Biosphere Reserve the forest remnants in the lowlands that have gentler slopes and a deep cover of leaf litter, a dense understorey, and high relative humidity and low temperature, to buffer the effects of edge related environmental changes and the invasion of species from the matrix.