The invasive Yellow Crazy Ant and the decline of forest ant diversity in Indonesian cacao agroforests

Throughout the tropics, agroforests are often the only remaining habitat with a considerable tree cover. Agroforestry systems can support high numbers of species and are therefore frequently heralded as the future for tropical biodiversity conservation. However, anthropogenic habitat modification can facilitate species invasions that may suppress native fauna. We compared the ant fauna of lower canopy trees in natural rainforest sites with that of cacao trees in agroforests in Central Sulawesi, Indonesia in order to assess the effects of agroforestry on occurrence of the Yellow Crazy Ant Anoplolepis gracilipes, a common invasive species in the area, and its effects on overall ant richness. The agroforests differed in the type of shade-tree composition, tree density, canopy cover, and distance to the village. On average, 43% of the species in agroforests also occurred in the lower canopy of nearby primary forest and the number of forest ant species that occurred on cacao trees was not related to agroforestry characteristics. However, A. gracilipes was the most common non-forest ant species, and forest ant richness decreased significantly with the presence of this species. Our results indicate that agroforestry may have promoted the occurrence of A. gracilipes, possibly because tree management in agroforests negatively affects ant species that depend on trees for nesting and foraging, whereas A. gracilipes is a generalist when it comes to nesting sites and food preference. Thus, agroforestry management that includes the thinning of tree stands can facilitate ant invasions, thereby threatening the potential of cultivated land for the conservation of tropical ant diversity.     

Interaction of local and landscape features in the conservation of Hungarian arable weed diversity

Question: How do local and landscape management contribute to weed diversity in Hungarian winter cereal fields? Location: Central Hungary. Methods: Vascular plants were sampled in 18 winter cereal fields along an intensification gradient according to nitrogen fertilization, in the first cereal rows (edge) and in the interior part of the fields. Weed species were divided into groups according to their residence time in Central Europe (native species, archaeophytes, neophytes) and nitrogen preference (low to medium, LMNP, and high, HNP species). The percentage of semi‐natural habitats was calculated in the 500 m radius circle. Effects of fertilizer use, transect position and semi‐natural habitats were estimated by general linear mixed models. Results: We recorded 149 weed species. Fertilizer had a negative impact on the species richness of archaeophytes and LMNP species, and on the cover of native weeds. There was greater species richness and weed cover at the edge of the fields than in the centre. A higher percentage of seminatural habitats around the arable fields resulted in greater total species richness, especially of archaeophytes and LMNP species. We found an interaction between the percentage of semi‐natural habitats and transect position for species richness of archaeophytes and LMNP species. Conclusions: Reduced use of fertilizers and a high percentage of semi‐natural habitats would support native and archaeophyte weed diversity even in winter cereal fields, while large amounts of fertilizer may promote invasion of neophytes. However, the beneficial effect of the semi‐natural habitats and greater species pool on the arable flora may prevail only in the crop edges.     

天然次生林和4种人工林树冠层蚂蚁功能多样性研究

为了探讨不同类型林地中树冠层蚂蚁功能多样性的变化,本研究采用树栖蚂蚁陷阱法调查云南省绿春县天然次生林和4种人工林的树冠层蚂蚁群落,并调查了植物多样性及植物垂直密度变化。测定54种蚂蚁的头长、头宽、胸长和后足腿节长,并计算和比较了不同类型样地间的功能丰富度、功能均匀度和功能离散度的差异。结果表明:(1)不同类型林地间树冠层蚂蚁的功能丰富度指数(FR_ic)有显著差异,紫胶林和紫胶林-玉米混农林显著高于桉树林、天然次生林和橡胶林,同时橡胶林显著高于桉树林;不同类型林地间树冠层蚂蚁的功能均匀度指数(FE_ve)有显著差异,天然次生林和紫胶林显著高于桉树林。不同类型林地间树冠层蚂蚁的功能离散度指数(FD_iv)有显著差异,桉树林、橡胶林和紫胶林显著高于紫胶林-玉米混农林,且橡胶林显著高于天然次生林。(2)树冠层蚂蚁功能均匀度随枯落物盖度的增加而升高;功能离散度随枯落物盖度、草本植物盖度和>300 cm处的垂直密度的增加而升高。不同林地类型中紫胶林的树冠层蚂蚁功能多样性相对较高,而这其中枯落物盖度、草本植物盖度和>300 cm处的垂直密度等环境因素起到一定积极的作用,因此对人工林进行合理的管护有利于生态系统功能的实现和保护。     

The effects of rainforest canopy loss on arboreal dung beetles in Borneo: implications for the measurement of biodiversity in derived tropical ecosystems

We examine the effect of selective timber extraction, and corresponding forest canopy loss, on arboreal dung beetles in the tropical rainforests of Sabah, Malaysian Borneo. Changes in vertical distribution of beetles are measured through differences in the abundance of beetles in ground-based pitfall traps in primary, logged and plantation forest. Previous research has demonstrated that arboreal dung beetles are not generally collected in pitfall traps in primary forest, but are present in large numbers above the ground in canopy vegetation: the presence of arboreal beetles in pitfalls in areas of reduced or modified canopy cover may therefore reflect a response to the absence or modification of their usual habitat, and the proliferation of these beetles nearer to the ground. In this paper, statistically significant differences are found in the abundance of beetles in ground pitfall traps from logged forest compared to primary forest. Results show that virtually no arboreal dung beetles are recorded in primary forest traps, with an increased abundance of arboreal dung beetles in traps from logged and plantation forest, with 1.72% of the total number of arboreal beetles recorded from primary forest, 22.32% from logged forest, and 75.96% from plantation forest. The presence of arboreal dung beetles in plantations demonstrates that arboreal dung beetles can survive outside their normal habitat, and we relate these observations to adaptations to upper rainforest canopy conditions, and proliferation of these microclimatic conditions in man-made habitats. Results are also discussed in terms of their relevance to the measurement of species richness and diversity in logged and other derived ecosystems, where mixing of the ground-based and arboreal faunas occurs.     

Microclimatic changes and the indirect loss of ant diversity in a tropical agroecosystem

Recent changes in the coffee agroecosystem of Costa Rica were used to study the mechanism of biodiversity loss in transforming agroecosystems, focusing on the ground-foraging ant community. Coffee farms are being transformed from vegetationally diverse shaded agroforestry systems to unshaded coffee monocultures. We tested the hypothesis that the high-light environment and lack of leaf litter cover in the unshaded system are the determinants of the differences in ground-foraging ant diversity. Four treatments were established within the light gaps of a shaded plantation: shade, leaf litter, shade plus leaf litter, and a control (no shade or leaf litter added). Ants were sampled using tuna fish baits and light and temperature were measured. Shade and leaf litter had a significant effect on the ant fauna but probably for indirect reasons having to do with species interactions. In both shade treatments, Solenopsis geminata, the tropical fire ant, decreased significantly while the other species increased. The possibility that the physical factor changes the nature of competitive interactions between the most abundant species is discussed.     

The importance of species range attributes and reserve configuration for the conservation of angiosperm diversity in Western Australia

In order to better understand the relationship between reserve design and the species represented by such designs, we examined the effectiveness of the Western Australian reserve system for conserving angiosperm diversity, and examined the characteristics of those species conserved. We overlayed species distribution data for 14 plant lineages with the distribution of the reserve system (8.5% of the State’s area) and identified the species that remained unprotected. We found that, depending upon the method employed, between 174 (5.7%) and 570 (18.7%) of species were not included within the reserve system. Two main unprotected regions were identified, one of which was also a centre of high diversity. Geographical range sizes of unprotected species were six times smaller than those species that were protected, while species richness of small-ranged endemic species coincided with general patterns of species richness. At the level of Western Australia’s bioregions we found that conservation effectiveness was most dependent on characteristics of the reserve system rather than characteristics (size and positioning) of species ranges. At this scale, the most effective way to conserve more species in Western Australia would be to conserve more land, while conservation would be most successful in a uniformly dispersed reserve system. Our results highlight the fact that reserve systems may take on two design approaches based on scale––at continental scales, reserves should be clustered around the hotspots of endemic species, while within regions, an evenly distributed reserve system will most adequately sample species.     

Recovery of species richness and conservation of native Atlantic forest trees in the cacao plantations of southern Bahia in Brazil

The Atlantic forests of southern Bahia in Brazil present great species richness and a high degree of endemism. A large part of these native forests were transformed into cacao plantations in an agroforestry system known locally as cabrucas, where native trees were culled and cacao was planted under the shade of remaining trees. The present study analyzed the influence of time of implantation (age) and time of abandonment of management practices on tree species diversity of cabruca plantations to evaluate the capacity for conservation and recovery of species richness of native Atlantic Forest trees in cabrucas. Phytosociological surveys were conducted in five cabrucas with different conditions of age and state of abandonment. All trees, including hemiepiphytes and excluding the cacao plants, with a minimum stem diameter of 10 cm at breast height, were surveyed within a 3-ha sampling area in each plantation. A total of 2514 individual trees belonging to 293 species and 52 families were recorded in the five cabrucas. The Shannon diversity index varied from 3.31 to 4.22 among the cabrucas and was positively correlated with the time of abandonment (r = 0.97). The new cabrucas showed the highest values of estimated total richness (Chao) and the highest proportion of late successional species than the old ones. All areas preserved a very high proportion of native forest species while the three old cabrucas showed a higher proportion of exotic species than the two new ones. Thus the exotic species seem to replace more of the native species in the long run because of management practices and local preferences. The cabrucas presented also a high capacity for the regeneration of tree species richness after abandonment. Simple alterations in management practices could improve the recruitment of late successional species in these areas. Economic incentives may be necessary for the farmers to adopt management practices to retain native species which bring no economic returns.     

The changing status of the Chalkhill Blue butterfly <Emphasis Type="Italic">Polyommatus coridon</Emphasis> in the UK: the impacts of conservation policies and environmental factors

The Chalkhill Blue Polyommatus coridon is a widespread butterfly of lowland calcareous grassland in southern Britain and is considered a good indicator of habitat condition. Polyommatus coridon has been identified as a Species of Conservation Concern in the UK Biodiversity Action Plan due to a greater than 25% decline in range size since the 1950s, with losses due to the combined effects of habitat destruction, agricultural intensification and neglect. Analysis of annual butterfly monitoring data (transects) collected at 161 sites from 1981 to 2000 show a three-fold population recovery had occurred. The increases were at established sites, with no re-colonisations or range expansion detected. The 1980s population increase coincided with increases across the species range in stock and rabbit Oryctolagus cuniculus grazing, as well as greater protection and management of sites through protected areas and nature reserves. During the 1990s agri-environment schemes were thought to be the main conservation and policy mechanism driving the favourable conservation status of P. coridon, by facilitating appropriate habitat restoration and management. Weather played a part in the species recovery, with warm, but wet summers associated with increases in abundance. The research provides strong evidence of an important conservation success with the UK Biodiversity Action Plan, with implications for other specialist biodiversity.     

Potential contribution of cryopreserved germ plasm to the preservation of genetic diversity and conservation of endangered species in captivity.

Demographic and genetic objectives of captive propagation programs for endangered species focus on establishing demographically secure populations that maintain adequate levels of genetic diversity. Long-term storage and utilization of cryopreserved germ plasm could extend the population's generation length and allow higher levels of genetic variation to be maintained in smaller populations. Since fewer breeding animals would be needed, more species would be "rescued" from extinction using the cage facilities currently available at existing institutions. Doubling generation lengths for callitrichid primates through use of cryopreservation could almost triple the number of species that could be rescued in world zoos. Additionally, long-term cryopreservation would allow for a third population, that of the frozen zoo. Three-way exchange of germ from germ plasm banks to captive and wild populations would increase genetic diversity at reduced risk and expense. Advances in reproductive technology and better understanding of the reproductive physiology of these animal populations are necessary to permit routine application of artificial insemination and embryo transfer using frozen-stored germ plasm.     

Floristic and ecological diversity of Ranunculus aquatic habitats in the sub-Atlantic range: implications for conservation

Ranunculus communities have been identified by the European Community Directive on Conservation of Natural and Semi-Natural Habitats as a key habitat in need of protection. The ecological requirements and floristic composition of three Ranunculus communities were investigated in North-Eastern France. We also aimed to determine the relationships between environmental parameters, Ranunculus abundance and species richness. R. fluitans communities clearly differed from the other communities by a higher evenness and species richness and by the occurrence of specific species. In contrast, R. penicillatus and R. peltatus communities displayed similar floristic content. Three different sub-associations were however identified within these communities. If alkalinity was determinant in isolating R. fluitans communities from the other stretches, the ecological ranges of the three communities strongly overlapped while considering parameters linked with other resources or with physical constraints. Further, no significant correlations were highlighted between environmental parameters, Ranunculus abundance and species richness. With respect to conservation, these observations may indicate the particular difficulty in defining each Ranunculus habitat on a European scale, and identify several key points which need to be taken into account when evaluating their status.     

The contribution of grazing to plant diversity in alpine grassland and heath

Abstract Grazing on transplants of a grass, a forb and a tree was examined in low-diversity grassland and more diverse heath in Australia's Snowy Mountains. Transplants were surrounded by 2 mm mesh netting. In one grassland plot, grazers (probably soil invertebrates) attacked 40–90% of tree and forb seedlings but no grass seedlings. In heath, which had about half the grass cover of grassland, grazers consumed grasses but not trees or forbs. The results suggest that grazers can depress diversity in grassland by attacking species other than grass. In heath, they may promote diversity by attacking only grass and releasing other species from competition.     

The role of natural habitats in agricultural systems for bird conservation: the case of the threatened Lesser Grey Shrike

Birds of agricultural systems are one of the most threatened groups of birds in Europe mainly due to their sharp population decline in recent decades. Habitat intensification resulting from more productive agricultural practices has been proposed as a major cause for these declines. However, especially in some regions such as Eastern European and Mediterranean countries, little is known about the ultimate factors linked to habitat intensification that drive population declines for different species. The Lesser Grey Shrike is a good study species for a better understanding of such processes since it is closely related to agricultural habitats in Europe and has suffered a strong decline in range and population size across the western half of the continent. In this study, we explored variations in breeding parameters of this shrike related to habitat composition and food supply at the territory level. We found that fledgling success of early breeders was related to the presence of natural (shrub lands) and semi-natural (fallows) habitats in the predominantly agricultural matrix that dominated breeding territories. Their influence on fledgling success appeared to be mediated by a higher arthropod availability on these habitats. Indeed, Lesser Grey Shrike showed a strong preference for these habitats as hunting locations. Our results highlight the importance of natural habitats in intensified agricultural land mosaics for the conservation of bird species. We suggest that management plans should pay special attention to the availability of habitats which serve as high quality food reservoirs and can potentially contribute to enhance the species population viability in an area. Finally, we discuss the possible link between agricultural intensification and Lesser Grey Shrike population declines in Western Europe.     

Effects of tsaoko (Fructus tsaoko) cultivating on tree diversity and canopy structure in the habitats of eastern hoolock gibbon (Hoolock leuconedys)

In this study, the quadrat method was used to study the effects of tsaoko(Fructus tsaoko) plantation on tree diversity and canopy structure of two natural habitats of eastern hoolock gibbon(Hoolock leuconedys): Nankang(characterized by extensive tsaoko plantation) and Banchang(relatively well reserved and without tsaoko plantation). Totally, 102 tree species from 25 families and 16 woody liana species from 10 families were recorded in Nankang, whereas 108 tree species from 30 families and 17 woody liana species from 12 families were recorded in Banchang. Although the tree species between two habitats is different, both habitats are characterized by enriched food resources for eastern hoolock gibbons, sharing similar dominant plant families. Due to tsaoko plantation, tree density proportion and diversity of forest layerⅠ(20 m) in Nankang were both significantly decreased, but the tree density of layerⅡ(10-20 m) increased. Likewise, in conjunction with these behavioral observations, we also address potential impacts of tsaoko plantation on the behavior of eastern hoolock gibbon.     

The distribution of the Rocky Mountain tailed frog (Ascaphus montanus) in relation to the fluvial system: implications for management and conservation

The mating, egg-laying, and larval development of tailed frogs occur in dynamic mountain streams. During the lengthy (up to 5 years) aquatic residency these species are vulnerable to channel disturbances that can be exacerbated by land uses. Researchers have highlighted specific tailed frog habitat associations but never in the context of fluvial system processes. Based on an extensive regional study with a watershed-wide sampling strategy, we demonstrate that the Rocky Mountain tailed frog (Ascaphus montanus) is limited to contributing basins of roughly 0.3–100 km² in size, with peak numbers in basins up to 35 km². We conclude that the primary determinant of tailed frog distribution patterns in a watershed is basin area, a proximate variable for channel process domain and regional stream discharge: tailed frogs are adapted to cascade and step-pool channel morphologies that characterize these small basins, presumably because they afford more bedform stability and pore-space refugia than do smaller, colluvial headwaters, or larger, floodplain-forming plane bed and pool-riffle bedforms of mainstem rivers. Secondarily, climate and physiography interact to influence occurrence and abundance at the watershed level by controlling such variables as runoff, water temperature, and sedimentation regime. This point has important management implications because it forces us to recognize that in complex ecosystems, wildlife habitat associations are contingent on site-specific interactions amongst fluvial system control variables: significance levels of any one variable to tailed frog distribution will not necessarily be consistent among basins. The study clearly shows that case studies can produce conflicting results when they lack a process-based understanding of ecological response.     

The contribution of edaphic heterogeneity to the evolution and diversity of Burseraceae trees in the western Amazon

Environmental heterogeneity in the tropics is thought to lead to specialization in plants and thereby contribute to the diversity of the tropical flora. We examine this idea with data on the habitat specificity of 35 western Amazonian species from the genera Protium, Crepidospermum, and Tetragastris in the monophyletic tribe Protieae (Burseraceae) mapped on a molecular-based phylogeny. We surveyed three edaphic habitats that occur throughout terra firme Amazonia: white-sand, clay, and terrace soils in eight forests across more than 2000 km in the western Amazon. Twenty-six of the 35 species were found to be associated with only one of three soil types, and no species was associated with all three habitats; this pattern of edaphic specialization was consistent across the entire region. Habitat association mapped onto the phylogenetic tree shows association with terrace soils to be the probable ancestral state in the group, with subsequent speciation events onto clay and white-sand soils. The repeated gain of clay association within the clade likely coincides with the emergence of large areas of clay soils in the Miocene deposited during the Andean uplift. Character optimizations revealed that soil association was not phylogenetically clustered for white-sand and clay specialists, suggesting repeated independent evolution of soil specificity is common within the Protieae. This phylogenetic analysis also showed that multiple cases of putative sister taxa with parapatric distributions differ in their edaphic associations, suggesting that edaphic heterogeneity was an important driver of speciation in the Protieae in the Amazon basin.     

Study on canopy disturbance regime and mechanism of tree species diversity maintenance in the lower subtropical evergreen broad-leaved forest,South China

ABSTRACT

The canopy disturbance, the gap environment, gap regeneration and maintenance of tree species diversity in the lower subtropical evergreen broad-leaved forest (LSEBF) of South China were studied in this paper. The most common manner of gap formation in the forest was by stem breakage. Most gaps were formed by two gap makers. The sizes of most expanded gaps (EG) and canopy gaps (CG) were in the range of 100 – 300 m² and 50 – 100 m², respectively. The ecological factors in gaps were analysed on the basis of contrasting measurement of the microclimatic regimes in gaps of different sizes and in non-gap stands. Tree species in the LSEBF were classified into 5 ecological species groups on the bases of their changes in order of importance values in gaps and in non-gap stands. Most of the species reached their peak of regeneration density around the gap sizes of 100 m² and 500 m². The curves of regeneration density vs. gap age for major species revealed two types. Regeneration densities of most species, and species diversity indices in gaps were greater than those in non-gap stands.     

Basic chromosomal proteins in lower eukaryotes: Relevance to the evolution and function of histones

Summary The occurrence of basic chromosomal proteins in lower eukaryotes provides a useful approach to the study of histone evolution and function in higher eukaryotes. The histones of higher plants and animals are very similar and some are nearly identical, suggesting a high degree of evolutionary conservation within this group of proteins. However, a literature survey reveals that in the lower eukaryotes the histone situation is quite variable. The ciliates, and the true and cellular slime molds possess basic chromosomal proteins that are very similar to the histones of higher plants and animals. Various other lower eukaryotes possess basic chromosomal proteins that resemble at least some of the major histone fractions, and some microorganisms possess basic chromosomal proteins that bear little or no relationship to higher plant and animal histones. Since histones play a major role in the control of gene expression and the maintenance of chromosome structure in higher organisms, the evolution of these proteins represents a major change in the packaging of DNA and the mode of regulating gene expression in eukaryotes.