Loss Of Plant Diversity Research Articles

Experimental Evidence of Functional Group-Dependent Effects of Tree Diversity on Soil Fungi in Subtropical Forests.

Deconvoluting the relative contributions made by specific biotic and abiotic drivers to soil fungal community compositions facilitates predictions about the functional responses of ecosystems to environmental changes, such as losses of plant diversity, but it is hindered by the complex interactions involved. Experimental assembly of tree species allows separation of the respective effects of plant community composition (biotic components) and soil properties (abiotic components), enabling much greater statistical power than can be achieved in observational studies. We therefore analyzed these contributions by assessing, via pyrotag sequencing of the internal transcribed spacer (ITS2) rDNA region, fungal communities in young subtropical forest plots included in a large experiment on the effects of tree species richness. Spatial variables and soil properties were the main drivers of soil fungal alpha and beta-diversity, implying strong early-stage environmental filtering and dispersal limitation. Tree related variables, such as tree community composition, significantly affected arbuscular mycorrhizal and pathogen fungal community structure, while differences in tree host species and host abundance affected ectomycorrhizal fungal community composition. At this early stage of the experiment, only a limited amount of carbon inputs (rhizodeposits and leaf litter) was being provided to the ecosystem due to the size of the tree saplings, and persisting legacy effects were observed. We thus expect to find increasing tree related effects on fungal community composition as forest development proceeds.

Remote sensing of unhelpful resilience to sea level rise caused by mangrove expansion: A case study of islands in Florida Bay, USA

Previous studies have found that vegetated coastal areas can increase their elevation indicating resilience to inundation by sea level rise (SLR), but the potential resilience were ignored or showed controversial results (i.e., soil accretion of vegetated areas vs. SLR). To estimate the resilience influences on 15 islands in Florida Bay (Florida, U.S.), our study used indicators (areas of the 15 islands and their mangrove forests) by analyzing 61-yr high-resolution historical aerial photographs and a 27-yr time-series of Landsat images. In these islands, coastal fringes are dominated by mangroves, and inland parts are dominated by brackish or freshwater species. Our results showed that: (1) despite rising sea levels, these low-lying islands significantly increased in area; (2) all of these islands had significant mangrove expansion, and the landward part of expansion led to the replacement of inland non-mangrove habitats; (3) there was a positive relationship between the increase of island area and mangrove expansion in these islands; (4) without the mangrove expansion, simulations showed that all of the islands had decreased areas by 2014 compared with that in 1953. On the basis of our spatial analyses and previous field studies in our study areas, these islands showed resilience to inundation and the mangrove expansion contributed to processes stabilizing these islands under SLR. Meanwhile, the mangrove expansion were partly at the expense of the habitats previously covered by non-mangrove species, thus potentially leading to a loss of plant diversity. Therefore, the mangrove expansion increased unhelpful resilience to maintain islands in a degraded state losing biodiversity, which should be considered in conservation accounting for future SLR. Moreover, the unhelpful resilience can be monitored by remote sensing based indicators, such as island area.

The 15-year post-treatment response of a mixed-conifer understory plant community to thinning and burning treatments

Disturbance is central to maintaining diversity in forest ecosystems. In the dry forests of the western United States, over a century of fire exclusion has altered the fire regimes of these forests, resulting in high fuel loads and a loss of plant diversity. Mechanical thinning and prescribed fire are widely used to restore structural complexity and species diversity in many western U.S. forests. While studies have shown that the reintroduction of fire into these forests initially promotes plant diversity, there is limited information on the persistence of this effect. We evaluated the effects of thinning and burning treatments on the understory plant community fifteen years after treatment in an old-growth, Sierran mixed-conifer forest. Using a full-factorial design, including three levels of thinning and two levels of burning, we found mechanical thinning and prescribed fire reduced litter depths and increased the availability of bare ground, resulting in an initial increase in herb cover. However, fifteen years after treatment, litter depths and shrub cover increased, resulting in a more homogenous understory community and a loss of herb cover. Overall, our results suggest that while thinning and burning treatments initially promote herbaceous plant cover, these effects are short lived in the absence of a second disturbance.

Plant Conservation in Spain: strategies to halt the loss of plant diversity

Plant Conservation in Spain: strategies to halt the loss of plant diversity

How do mycorrhizal suppression and plant functional group loss affect plant communities in Inner Mongolia Steppe?

AbstractAimsAlthough many studies have investigated how biodiversity loss impacts ecosystem functioning, we still have little understanding of how it interacts with arbuscular mycorrhizal fungi (AMF) to affect plant communities in natural grasslands. Here, we conducted a removal experiment to examine how AMF suppression and plant functional group (PFG) removal affect above‐ground productivity and community composition in a grassland, and to determine whether AMF alter the compensation ability of the remaining plants.LocationInner Mongolian grassland, China.MethodsWe suppressed AMF activities by applying Topsin®‐M as a soil drench and selectively removed PFGs to give three treatments (no removal, removal of C3 grasses and removal of both C4 grasses and forbs). We then measured various plant, soil and AMF parameters for each treatment combination.ResultsThe addition of Topsin‐M effectively reduced mycorrhizal root colonization across all of the PFG removal treatments. Furthermore, above‐ground productivity was significantly impacted by both the presence of AMF and the removal of PFGs. When C3 grasses were removed, neither C4 grasses nor forbs compensated for the biomass decline, and the presence of AMF did not affect their compensation ability. Conversely, C3 grasses could completely compensate for the removal of both C4 grasses and forbs, but the presence of AMF reduced their compensation ability. The removal of both C4 grasses and forbs dramatically increased the shoot P content of C3 grasses but AMF slightly decreased this. In contrast, AMF significantly increased the plant P content of C4 grasses and forbs across all three PFG removal treatments.ConclusionOur results highlight the importance of AMF in structuring natural above‐ground productivity under various biodiversity loss scenarios, and indicate that AMF will be able to modify vegetation dynamics in response to the future loss of plant diversity.

Leaf traits drive plant diversity effects on litter decomposition and FPOM production in streams.

Biodiversity loss in riparian forests has the potential to alter rates of leaf litter decomposition in stream ecosystems. However, studies have reported the full range of positive, negative and no effects of plant diversity loss on decomposition, and there is currently no explanation for such inconsistent results. Furthermore, it is uncertain whether plant diversity loss affects other ecological processes related to decomposition, such as fine particulate organic matter production or detritivore growth, which precludes a thorough understanding of how detrital stream food webs are impacted by plant diversity loss. We used a microcosm experiment to examine the effects of plant diversity loss on litter decomposition, fine particulate organic matter production, and growth of a dominant leaf-shredding detritivore, using litter mixtures varying in species composition. We hypothesized that plant diversity loss would decrease the rates of all studied processes, but such effects would depend on the leaf traits present in litter mixtures (both their average values and their variability). Our findings partly supported our hypotheses, showing that plant diversity loss had a consistently negative effect on litter decomposition and fine particulate organic matter production (but not on detritivore growth) across litter mixtures, which was mediated by detritivores. Importantly, the magnitude of the diversity effect and the relative importance of different mechanisms underlying this effect (i.e., complementarity vs. selection) varied depending on the species composition of litter mixtures, mainly because of differences in litter nutritional quality and trait variability. Complementarity was prevalent but varied in size, with positive selection effects also occurring in some mixtures. Our results support the notion that loss of riparian plant species is detrimental to key stream ecosystem processes that drive detrital food webs, but that the magnitude of such effects largely depends on the the order of species loss.

Effects of allelopathy and competition for water and nutrients on survival and growth of tree species in Eucalyptus urophylla plantations

Allelopathy and resource competition are considered to be two primary mechanisms responsible for loss of biodiversity in plantations of Eucalyptus species. However, these two processes are usually studied separately, and they have been rarely tested on native woody species. In this study, we used a bioassay to assess sensitivities of twenty broad-leaved tree species on roots, stem growth and seed germination to leaf aqueous extracts of Eucalyptus urophylla S.T. Blake and categorized them into two types: inhibited and uninhibited (including stimulated and unaffected). To compare the relative importance of allelopathy and resource competition, we planted these two species groups into the E. urophylla plantation separately and treated with three gradients of irrigation-nutrients. The results showed that the allelopathic effects of aqueous extract of E. urophylla were species-specific and could be inhibitory, neutral or stimulatory. Compared to the inhibited species, the uninhibited species grew faster and survived better after they were planted in an E. urophylla plantation for approximately 10 years, suggesting that allelopathy from E. urophylla is an important restraining factor on native woody communities. Individuals from both species groups grew faster following higher resource treatment at the early but not the late stage of growth. Saplings did not vary in their survival rates across resource gradients. This indicates that resource competition between E. urophylla and native woody species has only a limited role in reducing the diversity of native species in an E. urophylla plantation. We conclude that allelopathy is more important than resource competition in mediating the reduction in plant biodiversity in E. urophylla plantations. Our study suggests that mixing certain types of species (e.g. Helicia cochinchinensis, Pterospermum lanceaefolium, Cinnamomum burmanni, Machilus chinensis, Acmena acuminatissima and Castanopsis chinensis) in E. urophylla plantations can mitigate against plant diversity loss.

Plant and vegetation functional responses to cumulative high nitrogen deposition in rear-edge heathlands

Elevated atmospheric nitrogen (N) deposition is a major driver of change, altering the structure/functioning of nutrient-poor Calluna vulgaris-heathlands over Europe. These effects amply proven for north-western/central heathlands may, however, vary across the ecosystem's distribution, especially at the range limits, as heathlands are highly vulnerable to land-use changes combined with present climate change. This is an often overlooked and greatly understudied aspect of the ecology of heathlands facing global change. We investigated the effects of five N-fertilisation treatments simulating a range of N deposition rates (0, 10, 20, and 50 kg N ha−1 yr−1 for 1 year; and 56 kg N ha−1 yr−1 for 9 years) on the Calluna-plants, the plant functional groups, species composition and richness of two life-cycle stages (building/young- and mature-phase) of Calluna-heathlands at their rear-edge limit. Our findings revealed a dose-related response of the shoot length and number of flowers of young and mature Calluna-plants to the addition of N, adhering to the findings from other heathland locations. However, cumulative high-N loading reduced the annual growth and flowering of young plants, showing early signs of N saturation. The different plant functional groups showed contrasting responses to the cumulative addition of N: annual/perennial forbs and annual graminoids increased with quite low values; perennial graminoids were rather abundant in young heathlands but only slightly augmented in mature ones; while bryophytes and lichens strongly declined at the two heathland life-cycle stages. Meanwhile there were no significant N-driven changes in plant species composition and richness. Our results demonstrated that Calluna-heathlands at their low-latitude distribution limit are moderately resistant to cumulative high-N loading. As north-western/central European heathlands under high-N inputs broadly experienced the loss of plant diversity and pronounced changes in plant species dominance, rear-edge locations may be of critical importance to unravel the mechanisms of heathland resilience to future global change.

Patterns of plant diversity loss and species turnover resulting from land abandonment and intensification in semi-natural grasslands

Land-use changes cause biodiversity loss in semi-natural ecosystems worldwide. Biotic homogenization has led to biodiversity loss, mainly through declines in species composition turnover. Elucidating patterns of turnover in species composition could enhance our understanding of how anthropogenic activities affect community assembly. Here, we focused on whether the decreasing patterns in plant diversity and turnover of species composition resulting from land-use change vary in two regions. We estimated the species diversity and composition of semi-natural grasslands surrounding paddy fields in satoyama landscapes. We examined the differences in species diversity and composition across three land-use types (abandoned, traditional, and intensified) in two regions (Hyogo and Niigata Prefectures, Japan), which were characterized by different climatic conditions. We then assessed alpha-, beta-, and gamma-diversity to compare the patterns of diversity losses in the two regions as a result of land-use changes. In each region, gamma-diversity was consistently higher in the traditional sites compared to abandoned or intensified sites. The analyses revealed that most of the beta-diversity in traditional sites differed significantly from those of abandoned and intensified sites in both regions. However, the beta-diversity of total and perennial species did not differ between traditional and abandoned sites in the Hyogo region. We noted that the beta-diversity of total and perennial species in intensified sites was much lower than that in the traditional sites of the Niigata region. Overall, the patterns of alpha- and gamma-diversity loss were similar in both study regions. Although the biotic homogenization was caused by intensified land-use in the Niigata region, this hypothesis did not completely explain the loss of biodiversity in the abandoned sites in the Hyogo region. The present study contributes to the growing body of work investigating changes in biodiversity as a result of both biotic homogenization and differentiation in semi-natural ecosystems. Conservationists and policy makers should focus on patterns of species composition responded to land-use changes that continue to increase worldwide.

The Dangers of Being a Small, Oligotrophic and Light Demanding Freshwater Plant across a Spatial and Historical Eutrophication Gradient in Southern Scandinavia.

European freshwater habitats have experienced a severe loss of plant diversity, regionally and locally, over the last century or more. One important and well-established driver of change is eutrophication, which has increased with rising population density and agricultural intensification. However, reduced disturbance of lake margins may have played an additional key role. The geographical variation in water chemistry, which has set the scene for – and interacted with – anthropogenic impact, is much less well understood. We took advantage of some recently completed regional plant distribution surveys, relying on hundreds of skilled citizen scientists, and analyzed the hydrophyte richness to environment relations in five contiguous South-Scandinavian regions. For three of the regions, we also assessed changes to the freshwater flora over the latest 50–80 years. We found a considerable variation in background total phosphorus concentrations and alkalinity, both within and between regions. The prevalence of functional groups differed between regions in accordance with the environmental conditions and the species’ tolerance to turbid waters. Similarly, the historical changes within regions followed the same trend in correspondence to the altered environmental conditions over time. Small submerged species decreased relative to tall submerged and floating-leaved species along the regional and historical eutrophication gradients. These changes were accompanied by systematically greater relative abundance of species of higher phosphorus prevalence. We conclude that species traits in close correspondence with anthropogenic impacts are the main determinants of local, regional and historical changes of species distribution and occupancy, while pure biogeography plays a minor role. Conservation measures, such as re-oligotrophication and re-established disturbance regimes through grazing and water level fluctuations, may help reduce the tall reed vegetation, restore the former richness of the freshwater flora and safeguard red-listed species, although extended time delays are anticipated in nutrient-rich regions, in which species only survive at minute abundance in isolated refugia.

Local biodiversity erosion in south Brazilian grasslands under moderate levels of landscape habitat loss

Abstract Habitat loss is one of the greatest threats to biodiversity, exerting negative effects on the ecological viability of natural vegetation remnants. The south Brazilian grasslands belong to one of the largest temperate grassland regions in the world, but have lost 50% of their natural extent in the past 35 years. To date, there is no empirical evidence for the effects of habitat loss on these grasslands' biological diversity, undermining their conservation. Using data from a large‐scale biodiversity survey, we asked if local plant communities respond to levels of habitat loss representative of the entire region (≤50%). Vegetation in grassland remnants was sampled in 24 landscapes at three localities each, using nine plots per locality. To investigate whether species losses were a consequence of stochastic or nonrandom local extinctions and whether plant communities became more homogenized, we evaluated species richness, beta‐diversity components (spatial turnover and nestedness), and phylogenetic diversity, in respect to landscape change. In part of the landscapes, arthropods were sampled to investigate if loss of plant diversity had a cascading effect on other trophic levels. We evaluated generic richness of ants, an omnivore group with high levels of plant associations, in respect to a plant community's phylogenetic diversity. Local plant communities in landscapes with less grassland cover had fewer species, less spatial turnover, increased nestedness and lower phylogenetic diversity. Our results suggest that the observed species loss can be linked to taxonomic homogenization and is nonrandom, decreasing evolutionary diversity within the community. Furthermore, ant richness declined by 50% in plant communities with the lowest phylogenetic diversity, suggesting that effects of habitat loss propagate to higher trophic levels. Policy implications. We conclude that the biological diversity of south Brazilian grasslands, at the producer and consumer level, is at risk under the current rate of land‐use conversion, even at habitat losses below 50%. To avoid substantial biodiversity loss, conservation and more restrictive policies for conversion of native grasslands to different land uses in South Brazil are urgently needed.

Quarante ans de suivi dans la steppe du Sud-Oranais (Algérie) : changements de diversité et de composition floristiques

Forty years monitoring in an Algeria alfa steppe in southern Oran Region (Algeria) : plant diversity and composition changes. The loss of plant diversity as a degradation feature in arid steppic rangelands is one of the crucial concerns in the southern Mediterranean countries. These rangelands are facing two interacting driving forces : the arid climate with recurring and more or less lasting droughts on the one hand, and overgrazing on the other. Long-term monitoring of change in diversity and composition of plant communities is considered to be the best way to understand the history and mechanisms of ecosystem degradation and desertification. Starting from a pre-existing community in which alfa (Stipa tenacissima L.) was the dominant and the keystone species regarding ecosystem structure and functioning, forty years monitoring allowed analysing changes in floristic richness, diversity and community composition prior attaining its current state of degraded and impoverished steppe.

Local loss and spatial homogenization of plant diversity reduce ecosystem multifunctionality.

Biodiversity is declining in many local communities while also becoming increasingly homogenized across space. Experiments show that local plant species loss reduces ecosystem functioning and services, but the role of spatial homogenization of community composition and the potential interaction between diversity at different scales in maintaining ecosystem functioning remains unclear, especially when many functions are considered (ecosystem multifunctionality). We present an analysis of eight ecosystem functions measured in 65 grasslands worldwide. We find that more diverse grasslands-those with both species-rich local communities (α-diversity) and large compositional differences among localities (β-diversity)-had higher levels of multifunctionality. Moreover, α- and β-diversity synergistically affected multifunctionality, with higher levels of diversity at one scale amplifying the contribution to ecological functions at the other scale. The identity of species influencing ecosystem functioning differed among functions and across local communities, explaining why more diverse grasslands maintained greater functionality when more functions and localities were considered. These results were robust to variation in environmental drivers. Our findings reveal that plant diversity, at both local and landscape scales, contributes to the maintenance of multiple ecosystem services provided by grasslands. Preserving ecosystem functioning therefore requires conservation of biodiversity both within and among ecological communities.

Process strengths determine the forms of the relationship between plant species richness and primary productivity.

The current rates of biodiversity loss have exceeded the rates observed during the earth’s major extinction events, which spurs the studies of the ecological relationships between biodiversity and ecosystem functions, stability, and services to determine the consequences of biodiversity loss. Plant species richness-productivity relationship (SRPR) is crucial to the understanding of these relationships in plants. Most ecologists have reached a widespread consensus that the loss of plant diversity undoubtedly impairs ecosystem functions, and have proposed many processes to explain the SRPR. However, none of the available studies has satisfactorily described the forms and mechanisms clarifying the SRPR. Observed results of the SRPR forms are inconsistent, and studies have long debated the ecological processes explaining the SRPR. Here, I have developed a simple model that combines the positive and/or negative effects of sixteen ecological processes on the SRPR and models that describe the dynamics of complementary-selection effect, density effect, and the interspecific competitive stress influenced by other ecological processes. I can regulate the strengths of the effects of these ecological processes to derive the asymptotic, positive, humped, negative, and irregular forms of the SRPR, and verify these forms using the observed data. The results demonstrated that the different strengths of the ecological processes determine the forms of the SRPR. The forms of the SRPR can change with variations in the strengths of the ecological processes. The dynamic characteristics of the complementary-selection effect, density effect, and the interspecific competitive stress on the SRPR are diverse, and are dependent on the strengths and variation of the ecological processes. This report explains the diverse forms of the SRPR, clarifies the integrative effects of the different ecological processes on the SRPR, and deepens our understanding of the interactions that occur among these ecological processes.

Plant diversity increases predation by ground‐dwelling invertebrate predators

AbstractGlobal declines in biodiversity have raised concerns over the implications of diversity loss for the functioning of ecosystems. Plant diversity loss has impacts throughout food webs affecting both consumer communities and ecosystem functions mediated by consumers. Effects of plant diversity loss on communities of invertebrate predators have been documented, yet little is known about how these translate into variations in predation rates. We measured predation rates along two plant diversity gradients in grassland experiments manipulating species richness and functional diversity. Measurements were conducted at two different heights (ground and vegetation) and in two different seasons (spring and summer), using three different types of baits. Our results show that overall predation rates increase with plant species richness, but effects are seasonally variable and are much more pronounced on the ground than in the vegetation. Plant functional diversity did not consistently affect predation rates in our experiments. Potential mechanistic explanations for an effect of plant diversity on predation include higher complementarity between predator species or reduced intraguild predation with increasing structural complexity at higher plant diversity. These results underline the importance of high local plant diversity for natural pest control.

Sheep grazing and local community diversity interact to control litter decomposition of dominant species in grassland ecosystem

Large herbivore grazing, a major land use in grasslands, can constitute a feedback loop with local plant diversity to affect litter decomposition. Here we examined the interactive effects of sheep grazing and local plant community diversity on decomposition of litter of the dominant plant species (Leymus chinensis) in the meadow steppe of China. We found a faster litter decomposition rate in the local species-rich communities compared to the local species-poor communities in the absence of sheep grazing. However, in the presence of sheep grazing, the decomposition rate was significantly reduced in the local species-rich communities while increased in the local species-poor communities. Therefore, sheep grazing and local community diversity constituted a negative feedback loop to modify litter decomposition in this grassland ecosystem. The findings of this study indicate one outcome of herbivore grazing could be to homogenize grassland nutrient cycling in space by balancing litter decomposition rate among local communities, which therefore could increase the homogenization of metacommunity structure. Furthermore, reduced local community diversity may slow ecosystem process rates. Our study indicates that sheep grazing, or equivalent, offsets this negative effect of local plant diversity loss on litter decomposition.

Challenges and Perspectives for Achieving the Global Strategy for Plant Conservation Targets in Brazil

Brazil holds the largest flora in the world, with more than 35,000 described native species. However, a large portion of its flora is poorly known, and more than 2000 species are threatened with extinction. Because similar situations exist in virtually all other countries, the United Nations' Convention on Biological Diversity launched a program called the Global Strategy for Plant Conservation (GSPC). The vision of GSPC is to halt the continuing loss of plant diversity through the achievement of 16 outcome-oriented global targets set for 2020. Here we discuss the challenges ahead for countries committed to achieving GSPC targets and use the experience of the National Centre for Flora Conservation (CNCFlora), in Brazil, as a case study of successes in pursuing some targets, and some perceived failures. We offer information that might help other countries, decision makers, and policymakers to address difficulties and move themselves toward achieving GSPC targets. We also synthesize the main targets upon which CNCFlora acts, their current situation, and the desired improvements necessary to achieve targets by 2020. Finally, we provide recommendations to actors, stakeholders, decision makers, and policymakers in Brazil that could foster conservation actions and strategies in the country.

Decreased plant productivity resulting from plant group removal experiment constrains soil microbial functional diversity.

Anthropogenic environmental changes are accelerating the rate of biodiversity loss on Earth. Plant diversity loss is predicted to reduce soil microbial diversity primarily due to the decreased variety of carbon/energy resources. However, this intuitive hypothesis is supported by sparse empirical evidence, and most underlying mechanisms remain underexplored or obscure altogether. We constructed four diversity gradients (0-3) in a five-year plant functional group removal experiment in a steppe ecosystem in Inner Mongolia, China, and quantified microbial taxonomic and functional diversity with shotgun metagenome sequencing. The treatments had little effect on microbial taxonomic diversity, but were found to decrease functional gene diversity. However, the observed decrease in functional gene diversity was more attributable to a loss in plant productivity, rather than to the loss of any individual plant functional group per se. Reduced productivity limited fresh plant resources supplied to microorganisms, and thus, intensified the pressure of ecological filtering, favoring genes responsible for energy production/conversion, material transport/metabolism and amino acid recycling, and accordingly disfavored many genes with other functions. Furthermore, microbial respiration was correlated with the variation in functional composition but not taxonomic composition. Overall, the amount of carbon/energy resources driving microbial gene diversity was identified to be the critical linkage between above- and belowground communities, contrary to the traditional framework of linking plant clade/taxonomic diversity to microbial taxonomic diversity.

Botanic Gardens as Communicators of Plant Diversity and Conservation

This paper presents a unique survey on the role of botanic gardens as educational institutions that communicate plant diversity and conservation. An online survey was created to evaluate the present strategies developed by botanic gardens from all over the world to their visiting public. Dependent on their resources, either human, financial or both, all of them look for the accomplishment of Global Strategy for Plant Conservation’ target 14, promoting education on plants and awareness on human impacts in plant diversity loss. However, an educational group/department is more common in botanic gardens owned by the central government compared to the private, non-profit botanic gardens. The diversity of activities on plant diversity and conservation is influenced by the size and the number of staff in the garden. Only half of the surveyed botanic gardens have rooms exclusively assigned for educational activities and even less have garden spots for the same purpose. Online resources are particularly restricted to North America and Oceania botanic gardens. Although climate change is a brand new subject that could attract public to the garden, the most part of the gardens address biodiversity and plant identification as major themes of communication. Besides species label information and interpretation panels, self-guided visits, guided visits or activities/workshops are the common offers for public attraction. School visitors are still less than half of the total visitors and cover children from 6 to 13 years-old. These follow more guided visits and activities while general public choose self-guided visits.

Impacts of Myriophyllum aquaticum invasion in a Mediterranean wetland on plant and macro-arthropod communities

The invasion by alien macrophytes in aquatic ecosystems may produce a strong alteration of the native aquatic vegetation leading to heavy impacts for both plant and faunal native diversity. Myriophyllum aquaticum is an aquatic plant native of Southern America, invasive in several part of the world. We studied the effects of M. aquaticum invasion on plant and macro-arthropod communities in the canals around a protected wetland in the Mediterranean basin. We sampled plant and macro-arthropod communities in 10 transects in invaded and non-invaded tracts of the canals. We assessed the differences in plant and macro-arthropod species richness, diversity, taxonomic diversity and species composition between invaded and non-invaded habitats by means of univariate and multivariate analyses. Our study shows a significant loss of plant diversity between non-invaded to invaded sites, leading to communities numerically and taxonomically impoverished and highly divergent in the species composition. We also detected significant differences in arthropod species composition between invaded and non-invaded transects. Some taxa such as mosquitoes and malacostraca were more frequent in the M. aquaticum-dominated stands. Furthermore, the study shows a positive relation between invaded habitats and juvenile individuals of the invasive alien crayfish Procambarus clarkii.