Testing indicators of biodiversity for plantation forests

In many parts of the world, plantations make up a considerable proportion of the total forest area. In such regions, the identification of high biodiversity value stands and of management practices to enhance biodiversity is essential if the goals of Sustainable Forest Management are to be achieved. Since complete biodiversity assessments are rarely possible, efforts have been increasingly focussed on the use of indicators. Of particular interest are indicators applicable to individual stands that require no specialist taxonomic or technical knowledge to assess. Candidate biodiversity indicators had been identified in a previous study using data from Irish Sitka spruce (Picea sitchensis) and ash (Fraxinus excelsior) plantations but had yet to be tested on independent data. In the present study, the provisional indicators for vascular plant, bryophyte, spider and bird diversity were tested on data from Irish Scots pine (Pinus sylvestris), oak (Quercus petraea/Quercus robur), Sitka spruce and lodgepole pine (Pinus contorta) plantations. Conifer canopy cover was confirmed as an important biodiversity indicator, due to its influence on below-canopy microclimatic and structural conditions. Bryophyte species richness was higher in relatively high canopy cover plantations on poorly drained soils, while bird species richness was higher in more open plantations with high shrub cover. Coarse woody debris was an important substrate for forest-associated bryophytes, with higher species richness at higher volumes of deadwood. Both proximity to old woodland and stand age were confirmed as positive indicators for forest-associated vascular plants. This is related to dispersal limitation in these species, with nearby woodlands acting as important seed sources and colonisation increasing with time. Stand age was also confirmed as a positive indicator for forest-associated spiders and is related to the development of suitable habitat as the plantation matures. All of the confirmed indicators can be assessed without need for specialist knowledge, are ecologically meaningful and applicable to a range of forests managed under a clearfelling system. They can be used to assess the potential value of stands for the taxonomic groups to which they apply, as well as giving insights into management practices to enhance diversity in these groups.     

Large‐scale assessment of regeneration and diversity in Mediterranean planted pine forests along ecological gradients

Aim There is increasing concern regarding sustainable management and restoration of planted forests, particularly in the Mediterranean Basin where pine species have been widely used. The aim of this study was to analyse the environmental and structural characteristics of Mediterranean planted pine forests in relation to natural pine forests. Specifically, we assessed recruitment and woody species richness along climatic, structural and perturbation gradients to aid in developing restoration guidelines. Location Continental Spain. Methods We conducted a multivariate comparison of ecological characteristics in planted and natural stands of main Iberian native pine species (Pinus halepensis, Pinus pinea, Pinus pinaster, Pinus nigra and Pinus sylvestris). We fitted species‐specific statistical models of recruitment and woody species richness and analysed the response of natural and planted stands along ecological gradients. Results Planted pine forests occurred on average on poorer soils and experienced higher anthropic disturbance rates (fire frequency and anthropic mortality) than natural pine forests. Planted pine forests had lower regeneration and diversity levels than natural pine forests, and these differences were more pronounced in mountain pine stands. The largest differences in recruitment – chiefly oak seedling abundance – and species richness between planted and natural stands occurred at low‐medium values of annual precipitation, stand tree density, distance to Quercus forests and fire frequency, whereas differences usually disappeared in the upper part of the gradients. Main conclusions Structural characteristics and patterns of recruitment and species richness differ in pine planted forests compared to natural pine ecosystems in the Mediterranean, especially for mountain pines. However, management options exist that would reduce differences between these forest types, where restoration towards more natural conditions is feasible. To increase recruitment and diversity, vertical and horizontal heterogeneity could be promoted by thinning in high‐density and homogeneous stands, while enrichment planting would be desirable in mesic and medium‐density planted forests.     

Using null model analysis of species co-occurrences to deconstruct biodiversity patterns and select indicator species

Aim Using total species richness to characterize biodiversity may mask multiple response patterns of species. We propose a null model analysis of species co‐occurrence‐based classification to identify sets of species that may have similar (within‐groups) and distinct (between groups) response patterns to their environment. The classification should also provide an explicit framework for selecting indicator species with characteristic co‐occurrence patterns to predict overall species richness. Location Côte‐Nord, Québec, Canada. Methods We combined null‐model of species co‐occurrence and cluster analysis to identify species groups within diverse assemblages of ground‐dwelling and flying beetles of stands in a boreal forest mosaic; we then examined their co‐occurrence and response patterns to habitat characteristics. Best subset regressions were used to select indicator species of richness within each group, from which indicators of total species richness were selected. Results The identified species groups appeared to display contrasting co‐occurrence and response patterns to at least one of the stand‐level habitat characteristics. Among flying beetles, for example, richness increased with stand‐level heterogeneity for two groups and decreased for two other groups, but the relationship was non‐significant for the total richness. We identified 28 indicator species that explained > 80% (validated by bootstrap analysis) of the variation in total species richness. Predictive performance of indicators was higher than when their co‐occurrence were reshuffled, even under a highly constrained null model, indicating that co‐occurrence patterns contributed to their predictive performance. Main conclusions Co‐occurrence‐based classification appears as a promising and effective tool for deconstructing biodiversity into species groups which reflect their ecological commonalities and differences, thus reducing the risk of making faulty inferences about the causes underlying overall diversity patterns. The method provides an explicit framework for selecting indicator species representing different species groups that may reflect the multiple responses of species co‐occurring with them. Indicator species can be effective for predicting overall species richness.     

Can parasites be indicators of free-living diversity? Relationships between species richness and the abundance of larval trematodes and of local benthos and fishes

Measuring biodiversity is difficult. This has led to efforts to seek taxa whose species richness correlates with the species richness of other taxa. Such indicator taxa could then reduce the time and cost of assessing the biodiversity of the more extensive community. The search for species richness correlations has yielded mixed results, however. This may be primarily because of the lack of functional relationships between the taxa studied. Trematode parasites are highly promising bioindicators. Diverse assemblages of larval trematode parasites are easily sampled in intermediate host snails. Through their life cycles these parasites are functionally coupled with the surrounding free-living diversity of vertebrate and invertebrate animals. It has been shown that larval trematodes in snails correlate positively with bird diversity and abundance. Here, we explore whether trematodes also correlate with standard measures of fishes, and large and small benthos, for 32 sites in three wetlands. We found associations between trematodes and benthic communities that were not consistent across wetlands. The associations were, however, consistently positive for large benthic species richness and density. Some of the contrasting associations between trematode and benthos may be explained by negative associations between large and small benthos. We found no associations with fish communities (probably because of the inadequacy of standard “snapshot” sampling methods for highly mobile fishes). The results support further exploration of trematodes as bioindicators of diversity and abundance of animal communities. Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users.     

Plantations of exotic tree species in Britain: irrelevant for biodiversity or novel habitat for native species?

Novel or emergent ecosystems arising from human action present both threats and opportunities for biodiversity. It has been suggested that exotic species can “facilitate” or “inhibit” native biodiversity through habitat modification. In Britain, there is a discussion over the contribution to biodiversity of plantations of exotic conifer species as these are commonly thought to have little relevancy as a habitat for native biodiversity. To address this we compared the species richness of a range of different taxonomic groups (lichens, bryophytes, fungi, vascular plants, invertebrates and songbirds) in exotic and native forest stands of differing structural stages in northern and southern Britain. In terms of overall native species-richness there was no significant difference between the exotic and the native stands. In the north, six species groups showed higher values in the exotic Sitka spruce (Picea sitchensis) stands with the remaining six showing higher values in the native Scots pine (Pinus sylvestris) stands. Most notably, lichen species richness was much lower in the exotic stands compared to the native stands, whereas bryophyte and fungal species richness was proportionately higher in the exotic stands. In the south, five species groups (all invertebrate taxa) showed higher species richness in exotic Norway spruce (Picea abies) stands compared to native oak (Quercus robur) stands. Five species groups had higher species-richness in the oak stands, in particular lichens and fungi. It is concluded that emergent ecosystems of exotic conifer species are not irrelevant to biodiversity. Where already well-established they can provide habitat for native species particularly if native woodland is scarce and biodiversity restoration is an immediate priority.     

Impacts on biodiversity at Baltic Sea beaches

Sandy and shingle beaches were investigated in 2009 and 2010 along the coast of the Baltic Sea in northern Germany with the purpose of assessing biodiversity gradients from shingle to sandy beaches, from beach to primary dunes, and the impacts of tourism on biodiversity. On nine beach sites, ranging between 100% shingle and 99% sand without shingle, Carabidae, Staphylinidae, and Araneae were studied. Two of the six sandy beaches were open and four were closed to tourists. Additionally, trampling effects from tourists, species richness of plants, and plant cover were investigated on sixteen beaches. According to results, primary dunes showed higher species richness in carabids and spiders, but not in staphylinds. Shingle beaches exhibited lower species richness in Staphylinidae and Araneae, but not in Carabidae. As estimated by the Jackknife II method, shingle beaches were the lowest in total species richness. Trampling intensity ranged from 0 footprints m⁻² day⁻¹ on closed beaches, up to a maximum of 30 footprints m⁻² day⁻¹. On “intensively” used beaches (12 footprints m⁻² day⁻¹, on average), reduction of plant cover was more pronounced than on “extensively” used beaches (7 footprints m⁻² day⁻¹, on average). Both plant cover and plant species richness were lower on intensively and extensively used beaches than on closed beaches. In arthropods, only staphylind and spider species richness was significantly lower on open beaches than on closed beaches, but no differences were found in carabids. Referring to our results, trampling effects from tourists have high impact on species richness of sandy beaches, on both intensively and extensively used sites.     

Arbuscular mycorrhizal fungal communities in sub-Saharan Savannas of Benin, West Africa, as affected by agricultural land use intensity and ecological zone

The rapid decline of soil fertility of cultivated lands in the sub-Saharan savannas of West Africa is considered to be the main cause of the increasingly severe constraints of food production. The soils in this tropical area are highly fragile, and crop yields are limited by characteristically low levels of available phosphorus. Under such preconditions, the multiple benefits of the arbuscular mycorrhizal (AM) symbiosis are likely to play a pivotal role for maintaining natural soil fertility by enhancing plant nutrient use efficiency, plant health, and stabilization of a favorable soil structure. Thus, it is important to explore the impact of the commonly applied farming practices on the native AM fungal community. In the present study, we determined the AM fungal species composition in three ecological zones differing by an increasingly prolonged dry season from South to North, from the Southern Guinea Savanna (SG), to the Northern Guinea Savanna (NG), to the Sudan Savanna (SU). In each zone, four “natural” and four “cultivated” sites were selected. “Natural” sites were three natural forest savannas (at least 25–30 years old) and a long-term fallow (6–7 years old). “Cultivated” sites comprised a field with yam (Dioscorea spp.) established during the first year after forest clearance, a field under mixed cropping with maize (Zea mays) and peanut (Arachis hypogaea), a field under peanut, and a field under cotton (Gossypium hirsutum) which was the most intensively managed crop. Soil samples were collected towards the end of the wet season in each zone. AM fungal spores were extracted and morphologically identified. Soil subsamples were used to inoculate AM fungal trap cultures using Stylosanthes guianensis and Brachiaria humidicola as host plants to monitor AM root colonization and spore formation over 10 and 24 months, respectively. A total of 60 AM fungal species were detected, with only seven species sporulating in the trap cultures. Spore density and species richness were generally higher in the natural savannas and under yam than at the other cultivated sites and lowest under the intensively managed cotton. In the fallows, species richness was intermediate, indicating that the high richness of the natural savannas was not restored. Surprisingly, higher species richness was observed in the SU than in the SG and NG, mainly due to a high proportion of species in the Gigasporaceae, Acaulosporaceae, and Glomeraceae. We conclude that the West African savannas contain a high natural AM fungal species richness, but that this natural richness is significantly affected by the common agricultural land use practices and appears not to be quickly restored by fallow.     

Relationships between spatial configuration of tropical forest patches and woody plant diversity in northeastern Puerto Rico

The destruction and fragmentation of tropical forests are major sources of global biodiversity loss. A better understanding of anthropogenically altered landscapes and their relationships with species diversity and composition is needed in order to protect biodiversity in these environments. The spatial patterns of a landscape may control the ecological processes that shape species diversity and composition. However, there is little information about how plant diversity varies with the spatial configuration of forest patches especially in fragmented tropical habitats. The northeastern part of Puerto Rico provides the opportunity to study the relationships between species richness and composition of woody plants (shrubs and trees) and spatial variables [i.e., patch area and shape, patch isolation, connectivity, and distance to the Luquillo Experimental Forest (LEF)] in tropical forest patches that have regenerated from pasturelands. The spatial data were obtained from aerial color photographs from year 2000. Each photo interpretation was digitized into a GIS package, and 12 forest patches (24–34 years old) were selected within a study area of 28 km². The woody plant species composition of the patches was determined by a systematic floristic survey. The species diversity (Shannon index) and species richness of woody plants correlated positively with the area and the shape of the forest patch. Larger patches, and patches with more habitat edge or convolution, provided conditions for a higher diversity of woody plants. Moreover, the distance of the forest patches to the LEF, which is a source of propagules, correlated negatively with species richness. Plant species composition was also related to patch size and shape and distance to the LEF. These results indicate that there is a link between landscape structure and species diversity and composition and that patches that have similar area, shape, and distance to the LEF provide similar conditions for the existence of a particular plant community. In addition, forest patches that were closer together had more similarity in woody plant species composition than patches that were farther apart, suggesting that seed dispersal for some species is limited at the scale of 10 km.     

Ecological explanations for successful invasion of exotic plants

The intentional introduction of exotic species can increase the level of local biodiversity, enrich people’s material lives, and bring significant social and economic benefits that are also the symbols of human progress. However, along with the frequent intercourse among countries and regions, the frequency of uncontrolled crossregional migration of species is increased and there is a lack of scientific management strategy for the intentional introduction of exotic species. Exotic species invasion, which is behind habitat fragmentation, has become the second largest threatening factor to the maintenance of the global-scale level of biological diversity. Exotic species invasion can destroy the structure of an ecosystem, disturb the economic life of a society, and do harm to human health. In this paper, the authors review some of the ecological explanations for issues such as “what causes or mechanisms have led to the successful invasion of exotic species”, including the “ideal weeds characteristics”, “biodiversity resistance hypothesis”, “enemies release hypothesis”, “evolution of increased competitive ability hypothesis”, “niche opportunity hypothesis”, and “novel weapon hypothesis”. The authors also analyze and evaluate the background and theoretical basis of the hypotheses, providing explanations for some phenomena, as well as the deficiencies of these explanations.     

The socioeconomic conditions determining the development, persistence, and decline of forest garden systems

There is a range of forest management systems between pure extraction and plantation systems. Such “intermediate systems” range from wild forests modified for increased production of selected products to anthropogenic forests with a high-density of valuable species growing within a relatively diverse and complex structure. These systems, classed here as “Forest Garden Systems” (FGS), have important socioeconomic and ecological benefits, and yet they have been largely overlooked by researchers, development practitioners, and policy makers. Based on case examples and the authors’ experience, this paper analyzes the socioeconomic and institutional factors that explain the development, persistence, and decline of FGS. These systems combine productivity and biodiversity values and are important components in the diverse economic systems of their managers. As such, the model warrants increased attention to protect existing values, to support the adaptation of existing systems to changing circumstances, and to inform the development of new models of integrated forest management     

Identifying practical indicators of biodiversity for stand-level management of plantation forests

Identification of valid indicators of biodiversity is a critical need for sustainable forest management. We developed compositional, structural and functional indicators of biodiversity for five taxonomic groups—bryophytes, vascular plants, spiders, hoverflies and birds—using data from 44 Sitka spruce (Picea sitchensis) and ash (Fraxinus excelsior) plantation forests in Ireland. The best structural biodiversity indicator was stand stage, defined using a multivariate classification of forest structure variables. However, biodiversity trends over the forest cycle and between tree species differ among the taxonomic groups studied. Canopy cover was the main structural indicator and affected other structural variables such as cover of lower vegetation layers. Other structural indicators included deadwood and distances to forest edge and to broadleaved woodland. Functional indicators included stand age, site environmental characteristics and management practices. Compositional indicators were limited to more easily identifiable plant and bird species. Our results suggest that the biodiversity of any one of the species groups we surveyed cannot act as a surrogate for all of the other species groups. However, certain subgroups, such as forest bryophytes and saproxylic hoverflies, may be able to act as surrogates for each other. The indicators we have identified should be used together to identify stands of potentially high biodiversity or to evaluate the biodiversity effects of silvicultural management practices. They are readily assessed by non-specialists, ecologically meaningful and applicable over a broad area with similar climate conditions and silvicultural systems. The approach we have used to develop biodiversity indicators, including stand structural types, is widely relevant and can enhance sustainable forest management of plantations.     

Co-variation and indicators of species diversity: Can richness of forest-dwelling species be predicted in northern boreal forests?

Design and establishment of ecologically good networks of conservation areas often requires quick assessments of their biodiversity. Reliable indicators would be useful when doing such assessments. In order to explore the potential indicators for species richness in boreal forests, we studied (1) the co-variation of species richness and composition of species assemblages among beetles, polypores, birds and vascular plants, (2) the relationships between species richness and four boreal forest site types, (3) the relationship between species richness and forest physical structure and (4) the suitability of potential indicator groups within the four taxa to predict the species richness generally. The data show that there are probably not a single taxonomic or forest structural characteristic to be used as a general biodiversity indicator or surrogate for all the species. The correlations in species richness among the four taxa studied were low. However, group-specific indicators were obvious: forest site type was a good surrogate for vascular plant richness, and quantity and quality of dead wood predicted the species richness of polypores. The results support the view that different indicators shall be used for different forest types and taxonomic groups. These indicators should facilitate relatively rapid methods to assess biodiversity patterns at the forest stand level.     

Common and Uncommon Understory Species Differentially Respond to Restoration Treatments in Ponderosa Pine/Douglas-Fir Forests, Montana

Restoration treatments have been widely advocated to address declining conditions in Pinus ponderosa forests throughout the western United States. However, few studies have examined treatment effects on individual plant species or whether responses differ for common species and uncommon species (those with low abundance in the community)—information that may be critical in managing for long‐term biodiversity. We investigated understory species responses to restoration treatments in ponderosa pine/Douglas‐fir forests using a randomized block experimental design with three blocks and four treatments (control, burn‐only, thin‐only, and thin‐burn). Understory vegetation was sampled before treatment and for three consecutive years after treatment. We used richness and an index of uniqueness to compare responses of common and uncommon native understory species among treatments, and indicator species analysis to identify individual species that responded to each treatment. Treatments that included thinning had significantly more unique species assemblages than the control. The thin‐only treatment increased common native species richness, whereas all active treatments significantly increased uncommon native species richness over the control, especially the thin‐burn. Generally, life‐forms did not explain the responses of individual species, though in the final sampling year several graminoids were exclusively indicative of treatments that included thinning. Very few species had reduced abundance in the thinning and burning treatments by the final sample year, whereas many uncommon and short‐lived species benefited from active treatments, especially the combined thin‐burn treatment. Active restoration treatments in these forests may foster plant diversity by minimally impacting common species while significantly benefiting disturbance‐dependent native species.     

Quantitatively defining the conservation status of Natura 2000 forest habitats and improving management options for enhancing biodiversity

The main goal of Natura 2000 network is to guarantee the favourable conservation status of habitats and species ensuring European biodiversity. As a result, certain forest areas have been included in this network listed as 9230-Quercus pyrenaica habitat and 9340-Quercus ilex subsp. rotundifolia forest habitat. These areas were previously used for firewood extraction or livestock grazing and browsing. Nowadays these habitats are coppice forests with asexual regeneration, which is far from the desired conservation status. Traditional timber harvesting plans do not take account of the new objectives required for these Natura sites, which attempt to ensure biodiversity and recreational uses instead of simply focusing on timber production. This paper proposes a flexible methodology (applied to the study area “Dehesa Boyal” in ávila, Spain) for managing Natura 2000 forest sites by stands for sustainable forest management and the new requirements. The methodology has two phases. The first, “Division of the forest area into stands”, defines homogeneous patches of vegetation distinct in species composition, physiognomic structure and future management. The second, “Conservation status assessment of stands”, quantifies the conservation status of each previously classified stand considering a series of factors such as: functional health, restoration, floral richness and structure. A total value integrating the conservation status of stands is then calculated for the habitat. Both phases use Geographic Information System tools for managing information and visualizing results. The proposed methodology provides forest managers with a good knowledge of the territory and subsequently enables them to take appropriate conservation measures to maintain biodiversity.     

Regeneration of different plant functional types in a Masson pine forest following pine wilt disease

Pine wilt disease is a severe threat to the native pine forests in East Asia. Understanding the natural regeneration of the forests disturbed by pine wilt disease is thus critical for the conservation of biodiversity in this realm. We studied the dynamics of composition and structure within different plant functional types (PFTs) in Masson pine forests affected by pine wilt disease (PWD). Based on plant traits, all species were assigned to four PFTs: evergreen woody species (PFT1), deciduous woody species (PFT2), herbs (PFT3), and ferns (PFT4). We analyzed the changes in these PFTs during the initial disturbance period and during post-disturbance regeneration. The species richness, abundance and basal area, as well as life-stage structure of the PFTs changed differently after pine wilt disease. The direction of plant community regeneration depended on the differential response of the PFTs. PFT1, which has a higher tolerance to disturbances, became dominant during the post-disturbance regeneration, and a young evergreen-broad-leaved forest developed quickly after PWD. Results also indicated that the impacts of PWD were dampened by the feedbacks between PFTs and the microclimate, in which PFT4 played an important ecological role. In conclusion, we propose management at the functional type level instead of at the population level as a promising approach in ecological restoration and biodiversity conservation.     

The surrogacy potential of white-tailed sea eagle nesting habitat on islands of the Baltic Sea

In order to tackle the current biodiversity crisis, a plethora of tempting shortcuts, such as the surrogate species approach, have recently been used to pinpoint important areas for protection. At the same time, species-specific conservation programmes are implemented in order to ameliorate the status of target threatened species. In the cases where species-specific programmes are evaluated and found to provide no apparent benefit to the target species, it is important to evaluate whether such conservation efforts may benefit other taxa sharing the same landscape with the target species. Here we assess the surrogacy potential of white-tailed sea eagle (WTSE) nesting habitat as indicator of biodiversity richness (using vascular plants and fungi as surrogated taxa) on islands of the Archipelago Sea in South-western Finland. We compared species richness on islands with and without a WTSE nest. We found weak evidence that islands with a WTSE nest support higher richness of vascular plants than islands without a nest. Conversely, we found no evidence that WTSE nests could be valid surrogates for fungi species inhabiting old-growth forests. Within the spatio-temporal and ecological limits of the present study, we suggest that the nesting habitat of WTSE may hold some surrogate potential for taxa, such as vascular plants, that may indicate high habitat diversity. This finding however remains to be confirmed. At the same time, it appears evident that the WTSE nesting habitat has poor surrogate potential with regards to old-growth forests. Overall, our findings line up with a growing body of other studies calling for caution and careful evaluation of the surrogacy efficiency of single species.     

Deadwood as a surrogate for forest biodiversity: Meta-analysis of correlations between deadwood volume and species richness of saproxylic organisms

Deadwood is an important component of forest ecosystems on which many forest dwelling species depend. Deadwood volume is therefore widely used as an indicator of forest biodiversity, notably throughout Europe. However, using deadwood as an indicator has mostly been based on boreal references, and published references for temperate forests are scarce. As a result, the magnitude of the relationship between deadwood volume and species richness remains unclear for saproxylic species. We used meta-analysis to study the correlation between deadwood volume and the species richness of saproxylic beetles and fungi relative to several predictors at the forest stand level: biome, type of deadwood (log, snag, and stump) and decay class (fresh vs. decayed). We showed that the correlation between deadwood volume and species richness of saproxylic organisms was significant but moderate (r = 0.31), and that it varied only slightly between logs and snags or between decay stages. However, we found a strong biome effect: deadwood volume and species richness were more correlated in boreal forests than in temperate forests. This could be attributed both to differences in the history of forest management between biomes and to varying landscape patterns. Finally, we conclude that total deadwood volume is probably not a sufficient indicator of saproxylic biodiversity, and those additional variables (notably at the landscape level) such as type of deadwood or decay class should be integrated in deadwood monitoring. In addition, further forest research is needed to better assess the quantitative relationship between deadwood and saproxylic biodiversity, and in order to build indicators adapted to different biome contexts.     

Biodiversity and fish farming intensification in French fishpond systems

Fishponds are artificial ecosystems in which biodiversity may be strongly affected by fish farming management. We studied biodiversity variation along a gradient of fish farming intensification within a 180-pond sample of a French region to establish whether biodiversity primarily depended on extensive management with the alternative hypothesis that some habitat characteristics could compensate for the effect of intensification. We compared the relationships of three biodiversity indicators (breeding birds, protected plants, macrophytes) to an index of intensification and to habitat characteristics likely to influence each indicator. In all selected indicators, species richness did not vary according to the composite intensification gradient. Protected plant richness was best explained by periodic drainage, which could thus benefit biodiversity in intensified fishponds provided that shallow littoral areas are still present. Bird richness was linked to macrophyte cover and probably to reed bed areas. Macrophyte richness and coverage were negatively influenced by low water transparency and high fish biomass which seemed likely to affect bird habitat above 350–400 kg/ha. Aquatic vegetation, which may reflect interactive effects of environmental factors and fish farming management, may then contribute to assessment of the ecological status of fishponds under the E.U. Water Framework Directive.     

Chironomidae (Diptera) larvae assemblages differ along an altitudinal gradient and temporal periods in a subtropical montane stream in Northwest Argentina

The objective of this study was to analyze the spatial and temporal dynamics of Chironomidae larvae assemblages in a subtropical mountain river basin of northwestern Argentina. We hypothesized that they would respond to (1) environmental changes along the altitudinal gradient in the Yungas forests; (2) environmental changes caused by spates (e.g., increased discharge or sediment transportation). We sampled five sites along an altitudinal gradient of ca. 1,500 m (from 680 to 2,170 m) during low-water and high-water period for 2 years. The Chironomidae larvae assemblages varied along the altitudinal gradient and between sampling periods based on an indicator species analyses and an ordination analyses (NMDS). The best indicator for high altitude sites was “Genus X” followed by Onconeura sp.2, “Genus 9”, “Genus 10”, and Rheotanytarsus sp.2; while Rheotanytarsus lamellatus, Oliveiriella sanjavieri, and Thienemanniella sp. were good indicators for low altitude sites. O. sanjavieri and R. lamellatus were the best indicators for high-water period. The most relevant environmental variables influencing their spatial and temporal distribution were altitude, water temperature, conductivity, and pH. This study is the first to analyze and describe in detail the spatial and temporal distribution of Chironomidae larvae assemblages in northwestern Argentina, and most of the taxa reported here are new records for the region.     

Declines in plant species richness and endemic plant species in longleaf pine savannas invaded by <Emphasis Type="Italic">Imperata cylindrica</Emphasis>

Despite the widespread perception that non-native species threaten biodiversity, there are few documented cases of non-native species displacing rare or specialized native species. Here, I examined changes in plant species composition over 5 years during patch expansion of a non-native grass, Imperata cylindrica, in longleaf pine flatwoods in Mississippi, USA. I used a multivariate approach to quantify the degree of habitat specialization and geographic range of all species encountered. I examined losses of species collectively as a function of plant height (controlling for initial frequency) and then the relationship between height and the degree of association with longleaf pine flatwoods, disturbed habitats, and the outer Gulf Coastal Plain of the southeastern USA. Patch expansion resulted in dramatic declines in species richness and increases in ground-level shade at both sites in just 3 years. Most tall saplings, shrubs, and vines were not endemic to longleaf pine communities and were less likely to be displaced than short herbs, most of which were indicative of longleaf pine communities. These results suggest that invasion of longleaf pine communities by I. cylindrica will likely cause significant losses of short, habitat-specialists and reduce the distinctiveness of the native flora of these threatened ecosystems.