Mean Species Abundance Research Articles

Critical Loads for Nitrogen Based on Criteria for Biodiversity Conservation

The increased focus on biodiversity following inter alia the 1993 Convention on Biological Diversity and the EU Nature Directives has led to a demand for the inclusion of biodiversity effects in the development of air pollution policies in Europe. This paper presents a method for the calculation of critical loads for nitrogen with biodiversity protection as endpoint. The method has been used in a national assessment in Denmark based on national monitoring data. The method is based on the use of a coupled soil geochemical and plant occurrence model, VSD+/MOVE, with Mean Species Abundance as indicator and “no net loss” of biodiversity compared to a given reference year as criterion. Calculated critical loads with 2010, 1992, and 1950, respectively, as reference years are on average 9.4, 8.5, and 6.8 kg N ha−1 yr−1, and thereby substantial lower than the median value of the empirical critical load ranges for the same habitat types.

Collective decision making and social interaction rules in mixed-species flocks of songbirds

Associations in mixed-species foraging groups are common in animals, yet have rarely been explored in the context of collective behaviour. Despite many investigations into the social and ecological conditions under which individuals should form groups, we still know little about the specific behavioural rules that individuals adopt in these contexts, or whether these can be generalized to heterospecifics. Here, we studied collective behaviour in flocks in a community of five species of woodland passerine birds. We adopted an automated data collection protocol, involving visits by RFID-tagged birds to feeding stations equipped with antennae, over two winters, recording 91 576 feeding events by 1904 individuals. We demonstrated highly synchronized feeding behaviour within patches, with birds moving towards areas of the patch with the largest proportion of the flock. Using a model of collective decision making, we then explored the underlying decision rule birds may be using when foraging in mixed-species flocks. The model tested whether birds used a different decision rule for conspecifics and heterospecifics, and whether the rules used by individuals of different species varied. We found that species differed in their response to the distribution of conspecifics and heterospecifics across foraging patches. However, simulating decisions using the different rules, which reproduced our data well, suggested that the outcome of using different decision rules by each species resulted in qualitatively similar overall patterns of movement. It is possible that the decision rules each species uses may be adjusted to variation in mean species abundance in order for individuals to maintain the same overall flock-level response. This is likely to be important for maintaining coordinated behaviour across species, and to result in quick and adaptive flock responses to food resources that are patchily distributed in space and time.

How pastoralism changes savanna vegetation: impact of old pastoral settlements on plant diversity and abundance in south-western Kenya

For centuries, pastoralists have influenced savanna ecology through their construction of settlements, traditional movement patterns in search of forage, water and safety for their livestock. Construction of settlements initiates localised changes in the vegetation due to clearance of vegetation at construction and collection of construction materials. During the occupation period a lot of dung is deposited in and around settlements. When pastoral families abandon settlements and move away, they leave behind mud huts and livestock corrals surrounded by fences. These sites become nutrient-rich patches supporting a different abundance and diversity of plants and large mammals compared to the rest of the savanna. This study aimed to broaden our understanding of how pastoral land use influences plant diversity in East African savannas. Past work on the effects of settlements has been done in dry places (<600 mm rainfall) with relatively poor soils. To complement and extend these studies, we selected a contrasting site with high rainfall and rich soils in the Mara ecosystem of south-western Kenya. We sampled the occurrence of different plant species along transects radiating from 28 settlements abandoned by pastoralists and ranging in age from 2 months to 48 years on two different soil types. Mean plant species richness and abundance peaked at intermediate distances, 12.5 and 25 m from the edges of settlements. We recorded a total of 210 plant species during the study, 65 of which occurred only within the impact ring of the abandoned settlements. The effects of settlements on plants were stronger on shallow sandy soils than on deep clay soils. Our findings show that abandoned settlements were key sites for regeneration and replenishment of shrubs harvested by the Maasai, but support few other plants of biodiversity value. These unique habitat patches in the savanna ecosystem are under threat as pastoral Maasai become increasingly sedentary and as wildlife conservancies are established, thus reducing the number of abandoned settlements. In essence, the Maasai, by changing their traditional lifestyle, will reduce these nutrient hotspots and hence landscape heterogeneity and biodiversity.

The impact of river regulation on the biodiversity intactness of floodplain wetlands

Alteration of natural flow regime is considered a major threat to biodiversity in river floodplain ecosystems. Measurements of quantitative relationships between flow regime change and biodiversity are, however, incomplete and inconclusive. This hampers the assessment of human impact on riverine floodplain wetlands in global biodiversity evaluations. We systematically reviewed the scientific literature and extracted information from existing data sets for a meta-analysis to unravel a general quantitative understanding of the ecological consequences of altered flow regimes. From 28 studies we retrieved both ecological and hydrological data. Relative mean abundance of original species (mean species abundance, MSA) and relative species richness were used as effect size measures of biodiversity intactness. The meta-analysis showed that alteration of a natural flow regime reduces the MSA by more than 50 % on average, and species richness by more than 25 %. Impact on species richness and abundance tends to be related to the degree of hydrological alteration. These results can be used in strategic quantitative assessments by incorporating the relationships into global models on environmental change and biodiversity such as GLOBIO-aquatic.

Land use change and its effect on biodiversity in Chiang Rai province of Thailand

The Chiang Rai province of Thailand has experienced rapid deforestation and consequent land use change in recent years. This research carried out in Chiang Rai province simulated future land uses under three management scenarios and assessed their effect on biodiversity. The Dyna-CLUE model was used to simulate land uses of 2029 according to the management scenarios, and their effect on biodiversity was analyzed by the GLOBIO3 model. About 4% of total area of the province was deforested within 2002–2009 and has a possibility to lose more, that is, 7% by 2029. If this rate of deforestation continues, then biodiversity will be affected as shown by reduced ‘mean species abundance’ of 0.45 at present to 0.38 by 2029, whereby highly threatened area can be increased up to 15% of the total land area. Hence, protecting locations with higher biodiversity value can be efficient in conserving biodiversity.

Biodiversity and Habitat Changes Modelling Experiences in Ukraine and Eastern Europe Countries

This is updated study on biodiversity and its conditions in Ukraine and seven surrounding countries. It includes four different methods: the indicative-index approach, the Mean Species Abundance (MSA) and two species based approaches, one using habitat changes as driving factor (EEBIO) and the other includes climate change (SDM_GLM, BIOCLIM). The indicative-index methodology ‘BINU’ dealt with 128 species and 98 agrobiodiversity indicators-indices, and demonstrated low impact of climate change from 1950-2002. The EEBIO approach links species distribution maps, compiled from different sources to habitat change maps, resulting in a series of 900 GIS maps. The MSA-approach gives a general view and shows a low impact of climate change by 2002, and a high impact due to habitat loss. The GLM-approach provided detailed species-based maps of the expected changes in habitats condition caused by land use change and climate change, contrary to BIOCLIM. Finally, the selected 55 indicator species (vascular plants, insects, amphibians, birds and mammals) demonstrated a surprising diversity of GLM-trends by 2030-2050. It proved that expected climate change, together with land-use change would provoke numerous expected and unexpected species-habitat alterations. GLM- and BIOCLIM-based scenarios can not be the same. If the final GLM-scenarios are correct, then in the near future in Ukraine in particular, scientists and decision makers will by 2050 find about 4% of new species or will lose up to 13% of existing species.

Fish assemblages on a mitigation boulder reef and neighboring hardbottom

We compared the fish assemblages on a mitigation site to neighboring natural habitat. Artificial reefs made of limestone boulders were deployed offshore Florida in August–September 2003 as mitigation for an anticipated nearshore hardbottom burial associated with a planned beach nourishment. Boulders comprising a footprint of 36,017 m2 were deployed on sand substrate, adjacent to hardbottom, to replace an expected covering of 30,756 m2 hardbottom. Nourishment of the beach was initiated May 2005 and completed in February 2006. Fishes on the artificial mitigation reefs and neighboring natural hardbottom were counted annually in August, 2004 through 2008, with 30-m belt transects and rover-diver surveys. Across all surveys a total of 18,313 fish of 185 species was counted. Mean species richness and abundance were typically greater on the transects at mitigation reefs than on nearshore hardbottom (NHB). MDS plots of Bray–Curtis similarity indices show a clear distinction between the mitigation reefs and NHB fish assemblages regardless if the data were, or were not, standardized to account for rugosity differences. SIMPER analysis indicated the two assemblages had, on average, 75% dissimilarity. Thus, while the mitigation boulders exhibited greater abundance and species richness than the NHB, the two assemblages differed dramatically in structure. The mitigation reefs provided a habitat suitable for fish colonization. However, this habitat differed dramatically in size and appearance from impacted NHB and created a unique environment unlike the NHB. Thus, mitigation reefs in general, and boulder reefs specifically, should not be relied upon to provide an equitable replacement to NHB habitat loss.

Synergies and trade-offs between ecosystem service supply, biodiversity, and habitat conservation status in Europe

In the European Union (EU) efforts to conserve biodiversity have been consistently directed towards the protection of habitats and species through the designation of protected areas under the Habitats Directive (92/43/ECC). These biodiversity conservation efforts also have the potential to maintain or improve the supply of ecosystem services; however, this potential has been poorly explored across Europe. This paper reports on a spatial assessment of the relationships between biodiversity, ecosystem services, and conservation status of protected habitats at European scale. We mapped at 10km resolution ten spatial proxies for ecosystem service supply (four provisioning services, five regulating services and one cultural service) and three proxies for biodiversity (Mean Species Abundance, tree species diversity and the relative area of Natura 2000 sites). Indicators for biodiversity and aggregated ecosystem service supply were positively related but this relationship was influenced by the spatial trade-offs among ecosystem services, in particular between crop production and regulating ecosystem services. Using multinomial logistic regression models we demonstrated that habitats in a favourable conservation status provided more biodiversity and had a higher potential to supply, in particular, regulating and cultural ecosystem services than habitats in an unfavourable conservation status. This information is of utmost importance in identifying regions in which measures are likely to result in cost-effective progress towards both new biodiversity conservation and ecosystem services targets adopted by the Convention on Biological Diversity (CBD) and the EU Biodiversity Strategy to 2020.

Comparing the ecological footprint with the biodiversity footprint of products

Abstract This study compares the ecological footprints with the biodiversity footprints of products that result from land use and carbon dioxide emissions. The biodiversity footprints were quantified using mean species abundance statistics, whereas the ecological footprint refers to the impacts on bioproductivity. We used a data set of 1340 product systems subdivided into 13 product groups, which included various types of energy generation and material production. We found that the importance of direct land use vs. carbon dioxide emissions is different for biodiversity footprints compared to ecological footprints. This difference is particularly relevant if the environmental impact of bio-based products (dominated by direct land use) is compared with the environmental impact of fossil-based products (dominated by CO 2 emissions). Our results also show that the relative importance of different drivers can change over time within the biodiversity footprint and that the relative importance of climate change significantly increased for longer time horizons. As the interpretation of the biodiversity footprint can differ from the ecological footprint, the inclusion of impacts on biodiversity should be considered in the footprint calculation of products.

Assessing the impacts of livestock production on biodiversity in rangeland ecosystems

Biodiversity in rangelands is decreasing, due to intense utilization for livestock production and conversion of rangeland into cropland; yet the outlook of rangeland biodiversity has not been considered in view of future global demand for food. Here we assess the impact of future livestock production on the global rangelands area and their biodiversity. First we formalized existing knowledge about livestock grazing impacts on biodiversity, expressed in mean species abundance (MSA) of the original rangeland native species assemblages, through metaanalysis of peer-reviewed literature. MSA values, ranging from 1 in natural rangelands to 0.3 in man-made grasslands, were entered in the IMAGE-GLOBIO model. This model was used to assess the impact of change in food demand and livestock production on future rangeland biodiversity. The model revealed remarkable regional variation in impact on rangeland area and MSA between two agricultural production scenarios. The area of used rangelands slightly increases globally between 2000 and 2050 in the baseline scenario and reduces under a scenario of enhanced uptake of resource-efficient production technologies increasing production [high levels of agricultural knowledge, science, and technology (high-AKST)], particularly in Africa. Both scenarios suggest a global decrease in MSA for rangelands until 2050. The contribution of livestock grazing to MSA loss is, however, expected to diminish after 2030, in particular in Africa under the high-AKST scenario. Policies fostering agricultural intensification can reduce the overall pressure on rangeland biodiversity, but additional measures, addressing factors such as climate change and infrastructural development, are necessary to totally halt biodiversity loss.

Long-term variations in waterfowl populations in Loch Leven: identifying discontinuities between local and national trends

Loch Leven has been designated as a UK Ramsar Site (1976), a Site of Special Scientific Interest (1985) and a Special Protection Area (2000) due to its importance as a site for overwintering waterfowl. However, no comprehensive assessment of trends in waterfowl at the local versus national scale has been conducted at the site. Coherence between trends in 5-year mean species abundance for Loch Leven and Underhill Indexing Method values for Scotland (or GB in the case of geese) were assessed using principal components analysis for ten study species between 1968 and 2006. Five species showed trends at Loch Leven that were coherent with those at the Scottish scale (Eurasian Teal, Mute Swan, Great Cormorant, Pink-footed and Greylag geese). These species may not respond positively to local scale management. However, the other five species (Mallard, Coot, Great Crested Grebe, Tufted Duck and Pochard) showed distinct differences between local and national trends. A study of the feeding ecology for these species, the re-establishment of ringing effort and an assessment of waterfowl–wetland relationships are recommended to determine how changes in local food resources and habitat quality interact with macro-scale population dynamics to influence local and regional patterns of abundance.

Impact of flood intensity on aquatic insect communities in a Korean stream under monsoonal climate

As a consequence of climate change, localized torrential rainfall has increased in intensity and frequency in Northeast Asia under the influence of the monsoonal climate. The purpose of this study was to evaluate the impact of flood intensity on aquatic insect communities in a Korean stream, where the summer monsoonal flood is normal. Quantitative sampling was conducted according to stream reaches (upstream, midstream, and downstream sites) in Gapyeong stream, located in the central Korean peninsula, during July 2008–October 2009. Sampling was conducted within 48 hours after every rain event during the rainy season, and flood intensity was evaluated using the total amount of precipitation for 3 days before sampling. Precipitation was categorized in 100 mm increments. Water velocity and Froude number (Fr) were measured, and mean species abundance and species richness were determined. Habitat orientation groups (HOGs) were analyzed. Data were analyzed using nonmetric multidimensional scaling (NMS) ordination and two‐way analyses of variance .As a result, the velocity increased as precipitation increased at all sites, and the Fr at the upstream and midstream sites were below critical flow for all precipitation categories. The EPT‐group (Ephemeroptera, Plecoptera, and Trichoptera) together with Diptera were &gt;90% in abundance at all study sites. The mean abundance of some major taxa (i.e., Ephemeroptera and Plecoptera) decreased significantly as precipitation increased, particularly, at the downstream site. The mean abundance of all HOGs was more influenced by the relatively large amount of precipitation (e.g., &gt;200 mm) at all sites. According to NMS ordination, the amount of precipitation was the major factor determining the composition of aquatic insect communities in the study stream. In conclusion, aquatic insect communities in the Gapyeng stream were significantly influenced by the intensity of precipitation, and the impact was intensified at the downstream site.

Arthropods in Natural Communities in Mescal Agave (&lt;i&gt;Agave durangensis&lt;/i&gt; Gentry) in an Arid Zone

Problem statement: The arthropods have a very important role in the a rid zones due to their interactions with many organism and because t hey constituted an important element in the structure of the plant community. Nevertheless thei r importance there are few knowledge about the community of arthropods associated to vegetation in arid zones in the North of Mexico. The present study had the objective of determining the abundanc e, richness and diversity of arthropods in three localities where there are natural populations of m escal agave in the State of Durango, Mexico. Approach: In order to know the structure community of the a rthropods associated to the mescal agave, we perform a sampling schedule during March 2008 to November 2010 by direct collection, using transects in three different localities with the presence of mescal agave. The relative abundan ce, species richness, Shannon's diversity index, Pielou 's Index of evenness, Jaccard's similitude and Simpson's dominance indexes were determined. Results: A total of 4665 individual arthropods associated to mescal agave corresponding to 39 spec ies were found. El Mezquital had the highest abundance and relative abundance (44.1%) with 29 species. The mean species abundance was not significantly different between localities using Tu rkey's test. The highest density per unit of area w as found in El Mezquital (La Brena had the highest spe cies diversity (1.89), evenness (0.61) and dominance (0.78). At the taxon level, Hymenoptera had the highest number of species represented (14), followed by Coleoptera (9) and hemiptera (5), with the remaining taxons with four, two and one species each. Conclusion: The greatest similitude was observed between La Br ena and El Mezquital (46%) which shared seven taxons, while the least si militude was observed between El Venado and La Brena (29%). Dominance/diversity curves are presented for each locality. The species Caulotops sp., Acutaspis agavis , Chilorus sp., Scyphophorus acupunctatus and Peltophorus polymitus were the ones with highest relative abundance. Although the diver sity values are above the minimum, previously unreported arthropod species associated to mescal a gave were recorded. The results can be useful to know the dynamic in the community associated to agave, in order to development best conservation and exploit management of that important plant.

Distribución de flebotominos (Diptera: Psychodidae) en Quintana Roo, México

Se llevó a cabo un estudio faunístico en el estado de Quintana Roo para conocer la distribución, riqueza y abundancia de los flebotominos. Se observó una gran variabilidad del promedio deespecies y abundancia dentro y entre tres diferentes zonas (sur, centro y norte) en el estado. La mayor abundancia y riqueza se registró en la zona norte, en la zona centro y sur se capturaron igual número de especies, y la zona centro tuvo la menor abundancia. En cada zona fueron diferentes las especies dominantes, aunque, Lutzomyia shannoni y Lutzomyia cruciata se registraron dentro de las más dominantes distribuidas en las tres zonas. Entre las especies dominantes que se presentan en el estado se encuentran aquellas que son incriminadas como vectores de leishmaniasis en la Península de Yucatán. Los factores ambientales que se presentan en el estado son reflejados en las abundancias encontradas en las diferenteszonas de Quintana Roo.

Forestcheck: the response of epigeous macrofungi to silviculture in jarrah (Eucalyptus marginata) forest

Summary Species richness, abundance and composition of epigeous macro-fungi were monitored at 48 grids across four jarrah (Eucalyptus marginata) forest ecosystems in south-west Western Australia as part of an integrated monitoring project to examine responses to different timber harvesting and regeneration treatments. Forest that had never been harvested or had not been harvested for over 40 years was used as a reference, and compared to forest that had undergone shelterwood/selective cutting and gap release treatment after 1988. Silvicultural treatment also included post-harvest burning. All epigeous species of macrofungi and their abundance were recorded from autumn surveys at each grid. A total of 450 species were recorded. Overall mean species richness and abundance was similar but the composition of species assemblages contributing to macrofungal communities differed significantly between silvicultural treatments and reference forest. Sixty-nine species were restricted to reference forest while 35 were restricted to shelterwood/selective cut and 62 to gap release treatment. In all treatments, the overall mean number of species per grid recorded fruiting on soil was 2–4 times higher than that recorded on litter or wood. Species richness of sporophores recorded on both soil and litter was similar for all treatments, but was significantly lower on wood in reference forest compared to the gap release treatment. Mean sporophore abundance was significantly higher on litter and lower on wood in reference forest compared with silviculturally treated forest. Because fire is an integral part of jarrah forest silviculture, it was not possible to separate the singular effect that either tree removal or fire had on macrofungal communities. However, in different time-since-treatment classes the overall composition of species assemblages was different, but species richness and abundance for each silvicultural treatment were similar. Each forest ecosystem supported its own unique fungal community, which supports the concept of ecosystems in jarrah forest based on forest structure and understory vegetation resulting from variation in climate, soils and landforms. Current conservation policy and silviculture practice in jarrah forest produces a landscape mosaic containing early succession stands through to mature forest across the landscape, which is important for the maintenance of fungal biodiversity. Much of the fungal population in jarrah forest, however, remains unknown and only a long-term commitment to survey and monitoring will improve knowledge on the diversity and ecology of these important organisms and ensure their consideration in future management decisions.

Forestcheck: the response of vascular flora to silviculture in jarrah (Eucalyptus marginata) forest

Summary Forest understorey vascular plants were monitored across a sequence of time since treatment to assess the effects of silviculture (timber harvesting and regeneration systems) in jarrah (Eucalyptus marginata) forest in south-west Western Australia. Species richness, abundance and structure were assessed at 48 sites in four jarrah forest ecosystems. Monitoring grids in reference forest, which was either uncut or had not been harvested for at least 40 y, were compared to grids in forest that had undergone shelterwood/selective cut and gap release silvicultural treatments. A total of 446 plant species was recorded of which 68, 22 and 35 species were recorded on only one grid within the reference, shelterwood/selective cut and gap release treatments respectively. Silvicultural treatments had no significant long-term effect on mean species richness and abundance of understorey plants, but had a distinct influence on plant community composition. Reference forest had more species of small and medium shrubs compared with silvicultural treatments. Xanthorrhoea preisii (a grass tree) was significantly less common in silvicultural treatments compared with reference forest and Allocasuarina fraseriana (a small to medium tree) and Kennedia coccinea (a vine) were more common on harvested grids. The mean number of plant species per grid was not significantly different between treatments or forest ecosystems. There was, however, strong regional variation in plant community composition, especially in the Jarrah Blackwood Plateau and Jarrah South forest ecosystems and which probably reflects the influence of climatic and edaphic factors on jarrah forest species composition. Dominance-diversity curves for each treatment showed that ranking of species with high abundance was similar in all treatments, but varied between treatments for species with very low abundances. There was no significant relationship between species richness and time since last fire because field assessments were carried out at least 3–13 y after disturbance, by which time species assemblages had stabilised.

Impacts of agricultural land-use changes on biodiversity in Taihu Lake Basin, China: a multi-scale cause–effect approach considering multiple land-use functions

This paper aims to assess the impacts of agricultural land-use changes on biodiversity in Taihu Lake Basin, China, and to identify possible conservation strategies. We used the mean species abundance (MSA) approach, building on simple cause–effect relationships between environmental drivers and biodiversity impacts at the global level. Our assessment estimated that 21% of the original species in the undisturbed ecosystem were present in 2000. We also analysed and reviewed agricultural pressures at different spatial scales to enable the development of conservation strategies at regional and farm levels. This analysis showed, first, that intensive crop management is reflected by the amount of fertilisers applied. Policies and technologies aiming to reduce environmental impacts have been ineffective. Second, the abundance of semi-natural elements was found to be low and the fragmentation high. To link agricultural pressures to the MSA approach, we propose a multi-scale cause–effect approach, which can be linked to other land uses. This approach is useful to provide a quick scan of biodiversity status and identify conservation strategies. Training farmers to use site-specific nutrient management should be stimulated. Furthermore, acknowledging multiple land-use functions will help to develop biodiversity conservation strategies that are acceptable to farmers and policymakers.

Projecting Land-Use Change and Its Consequences for Biodiversity in Northern Thailand

Rapid deforestation has occurred in northern Thailand over the last few decades and it is expected to continue. The government has implemented conservation policies aimed at maintaining forest cover of 50% or more and promoting agribusiness, forestry, and tourism development in the region. The goal of this paper was to analyze the likely effects of various directions of development on the region. Specific objectives were (1) to forecast land-use change and land-use patterns across the region based on three scenarios, (2) to analyze the consequences for biodiversity, and (3) to identify areas most susceptible to future deforestation and high biodiversity loss. The study combined a dynamic land-use change model (Dyna-CLUE) with a model for biodiversity assessment (GLOBIO3). The Dyna-CLUE model was used to determine the spatial patterns of land-use change for the three scenarios. The methodology developed for the Global Biodiversity Assessment Model framework (GLOBIO 3) was used to estimate biodiversity intactness expressed as the remaining relative mean species abundance (MSA) of the original species relative to their abundance in the primary vegetation. The results revealed that forest cover in 2050 would mainly persist in the west and upper north of the region, which is rugged and not easily accessible. In contrast, the highest deforestation was expected to occur in the lower north. MSA values decreased from 0.52 in 2002 to 0.45, 0.46, and 0.48, respectively, for the three scenarios in 2050. In addition, the estimated area with a high threat to biodiversity (an MSA decrease >0.5) derived from the simulated land-use maps in 2050 was approximately 2.8% of the region for the trend scenario. In contrast, the high-threat areas covered 1.6 and 0.3% of the region for the integrated-management and conservation-oriented scenarios, respectively. Based on the model outcomes, conservation measures were recommended to minimize the impacts of deforestation on biodiversity. The model results indicated that only establishing a fixed percentage of forest was not efficient in conserving biodiversity. Measures aimed at the conservation of locations with high biodiversity values, limited fragmentation, and careful consideration of road expansion in pristine forest areas may be more efficient to achieve biodiversity conservation.

Logging Concessions Can Extend the Conservation Estate for Central African Tropical Forests

The management of tropical forest in timber concessions has been proposed as a solution to prevent further biodiversity loss. The effectiveness of this strategy will likely depend on species-specific, population-level responses to logging. We conducted a survey (749 line transects over 3450 km) in logging concessions (1.2 million ha) in the northern Republic of Congo to examine the impact of logging on large mammal populations, including endangered species such as the elephant (Loxodonta africana), gorilla (Gorilla gorilla), chimpanzee (Pan troglodytes), and bongo (Tragelaphus eurycerus). When we estimated species abundance without consideration of transect characteristics, species abundances in logged and unlogged forests were not different for most species. When we modeled the data with a hurdle model approach, however, analyzing species presence and conditional abundance separately with generalized additive models and then combining them to calculate the mean species abundance, species abundance varied strongly depending on transect characteristics. The mean species abundance was often related to the distance to unlogged forest, which suggests that intact forest serves as source habitat for several species. The mean species abundance responded nonlinearly to logging history, changing over 30 years as the forest recovered from logging. Finally the distance away from roads, natural forest clearings, and villages also determined the abundance of mammals. Our results suggest that logged forest can extend the conservation estate for many of Central Africa's most threatened species if managed appropriately. In addition to limiting hunting, logging concessions must be large, contain patches of unlogged forest, and include forest with different logging histories.

Helminth infracommunities of the maculated toad Amietophrynus regularis (Anura: Bufonidae) from Ismailia, Egypt

The objective of the present work was to study the helminth infracommunities of Amietophrynus (Bufo) regularis and the possible effects of intrinsic and extrinsic factors on infracommunity structure and on the infection parameters of each parasite species involved. A total of 129 A. regularis were collected from Ismailia, Egypt, over 3 seasons. Helminth infracommunities consisted of 8 helminth taxa (1 monogenean, 1 digenean, 1 cestode, 3 nematodes, and 2 acanthocephalans [1 adult and 1 cystacanth]). Aplectana macintoshii had the highest prevalence (82.94%), mean abundance (73.74), and mean intensity (88.91) and can be considered a core species. A. macintoshii dominated in 68.99% of the infracommunities, with a high Berger-Parker index value (0.9). Only 9 toads were uninfected; the remainder harbored between 1 and 7 helminth species and 1 to 632 ind. Mean species richness and abundance were 2.13 +/- 0.13 and 81.34 +/- 13.60, respectively, while evenness and diversity were 0.3 and 0.44, respectively. The results revealed that season, host sex, and age played significant roles in determining infracommunity species richness. The patterns of helminth infracommunity richness and diversity were similar to those previously observed in other amphibian hosts. This study indicated that the helminth community of A. regularis was depauperate.