1,721,177 research outputs found
Quantifying plant species diversity in coastal dunes: a piece of help from spatially constrained rarefaction
No full textSince coastal dunes are one of the most vulnerable landscapes in Europe, their maintenance requires specific conservation and monitoring programs. In this paper, the coastal dune systems of two natural parks located in central Italy were analysed aiming at: (1) assessing diversity patterns of all vascular species, endemic and alien taxa in plant communities along the coast-to-inland gradient; (2) comparing these patterns between coastal sections characterised by different dynamical processes (accreting, stable and erosive coasts); (3) testing the differences induced by the methodological approach used to characterise these patterns. Twenty-one transects were randomly positioned perpendicular to the shoreline on the whole coastal area (30 km in length) and the full spectrum of plant communities was sampled. Patterns of plant diversity was assessed using spatially explicit methods, namely Spatial Constrained Rarefaction (SCR), able to avoid the confounding effect of spatial autocorrelation. Results showed that species richness varied significantly between plant communities along the coast-to-inland gradient with the highest values at level of mobile dunes and transition dunes. Species richness was significantly higher in stable coastal dunes than those found in accreting and in erosive dunes. In fact, sand dynamics (accumulation as well as erosion) creates periodic vegetation disturbances affecting composition variability and succession. SCR methodology avoided overestimation in species richness when compared to classical rarefaction curves. Our findings pinpointed that coastal plant communities create a highly spatially structured mosaic in which mobile dunes represent the highest compositional heterogeneity. Local managers are encouraged to consider these results for planning adequate conservation strategies
Characterization of insect–pollinator biodiversity in agrochemical-contaminated agricultural habitats
Full text linkThe extensive application of agrochemicals in agricultural habitats in the Southern Highlands of Tanzania (SHOT) is supposed to negatively impact the biodiversity community of insect–pollinators (INPOs). However, in light of existing knowledge, there are no studies to back up this claim. We carried out field surveys in the SHOT to assess and characterize the INPO biodiversity community in agricultural habitats and compare it with protected habitats. Direct observations, transect counts, sweep netting, and pan trap techniques were used for sampling the INPOs. Overall, the INPOs’ relative abundance (57.14%) and species diversity index in protected habitats were significantly higher compared to agricultural habitats. Similarly, we recorded a higher number of plant–INPO interactions in protected habitats than agricultural habitats. Our results suggest that, in contrast to protected habitats, agrochemicals might have driven out or discouraged INPOs from agricultural habitats, resulting in dwindling species richness, diversity, and abundance. This could be due to agrochemical contamination that impairs the quantity and quality of floral resources (nectar and pollen) required by INPOs. Alternatively, protected habitats seemed healthy and devoid of agrochemical contamination, which attracted many INPOs for foraging and nesting. Thus, in order to maintain healthy agricultural habitats and support INPO biodiversity, conservation agriculture is imperative
A framework for assessing forest habitat connectivity loss and optimising reforestation efforts on the example of a hydropower project
Full text linkThe development of renewable energy, such as hydropower, often leads to the loss and fragmentation of terrestrial habitats, with significant effects on biodiversity. However, these impacts are often overlooked or underestimated in Environmental Impact Assessments (EIAs). In this study, we proposed a framework that explicitly integrates forest habitat connectivity into EIAs and environmental planning, addressing both impact assessment and recommendations for offset. The framework included (i) an evaluation of forest habitat connectivity loss by comparing before- and after-construction scenarios and (ii) a spatial analysis to prioritise reforestation activities aimed at restoring connectivity for wildlife species with varying movement abilities. We applied this framework to a proposed hydropower project in Nepal and found a major loss of forest habitat connectivity within the project footprint and up to 15 km away, indicating substantial loss of forest connectivity and a landscape-scale impact. In total, 94.1 km2 of deforested areas were identified, and potential reforestation sites were ranked using the Integral Index of Connectivity across three dispersal distances (500 m, 1 km and 2 km). Priority reforestation sites were identified both at landscape-level and within riparian zones, with 15% and 36% of the sites, respectively, emerging as top priorities for reforestation across all the dispersal distances. Our findings highlight the importance of explicitly addressing habitat connectivity in EIAs and environmental planning, and show how connectivity-based prioritisation can guide effective reforestation offsets, promoting a better balance between energy development and biodiversity conservation
Non-native species distribution along the elevation gradient in the western Italian Alps
Full text linkIn this work the occurrence of non-native species was recorded along the elevation gradient in the Alps, in order to establish their distribution pattern, their current altitudinal limits and to elucidate which species are presumably adapted to higher elevations. Plots were located along the course of rivers in five valleys from 100 to 2100 m a.s.l. Sixty-eight non-natives were recorded in the study area. The proportion of invasives was found to be much higher in the study area then in the whole administrative region. The number of non-natives per plot decreased strongly with increasing elevation. The great majority (94%) of the non-native species grows at the lowest elevations, while only 6% survive up to 1500 m and none was found above this limit. Results were interpreted considering the factors driving the invasion process (disturbance, the native communities' resistance to invasion, propagule pressure, climatic conditions) and plant traits with particular respect to preadaptation to the harsh climate, which increases progressively with elevation. Results confirm that the Alps are not immune from invasion, at least up to medium elevation
A spatially explicit measure of beta diversity
No full textPlant communities are generally spatially structured. Therefore, in order to enhance the interpretation of distance-dependent community patterns, spatially explicit measures of β-diversity are needed that, besides simple species turnover, are able to account for the rate at which biological similarity decays with increasing distance. We show that a multivariate semivariogram computed from species presence and absenge data can be considered as a space-dependent alternative to existing definitions of β-diversity. To illustrate how the proposed method works, we used a classical data set from a second-growth piedmont hardwood fores
Local and regional scale biodiversity patterns of forest snail assemblages in Tuscany (central Italy)
No full textThe land mollusc faunas of three forest areas of Tuscany (central Italy) were sampled to test the effect of geographical and environmental factors on the structure of biodiversity. A total of 60 sites were surveyed in the years 2009-2011, recording species richness and abundance of snails in 400 m2 plots randomly selected in beech and oak woods. Sampling strategy relied on a combination of visual search and litter analysis. Environmental variables (topsoil pH and altitude) and UTM coordinates were recorded to detect relationships with species richness and number of individuals per plot. Abundance data were analyzed using non-metric multidimensional scaling and canonical correspondence analysis; faunal similarity within and between areas was computed by the Bray Curtis index and snail assemblages of the two forest types were compared. A total of 55 species were recorded, with low values of local richness and abundance per site compared to other forest sites in central and northern Europe. Total richness was similar in the three areas, but composition and local richness varied significantly between them. Geographical factors explained the highest percentage of variance, while habitat type, altitude and pH only accounted for a minor part. Internal similarity was greater than between-area similarity in two out of three areas. Beech forests had richer and more heterogeneous faunas, but lower levels of abundance than oak woods. The results are discussed in terms of historical biogeography and local environmental conditions, and compared with those from similar surveys across Europe
Landscape effects on diversity of semi-natural grasslands
No full textWe studied how the landscape structure (percentage cover and diversity of surrounding habitats) affects different components of species diversity (alpha, beta and gamma) of vascular plants in semi-natural grasslands in the Slovak Republic. We analyzed all grasslands combined as well as four main types delimited according to their position along a moisture gradient (xerophilous, sub-xerophilous, mesophilous and wet grasslands). We used grassland records stored in the Slovak Vegetation Database. The geographically stratified dataset included 3795 plots with 1221 species of vascular plants. Along with the total number of species in the vegetation plots, we considered the numbers of target grassland species, forest species, archaeophytes, neophytes and species with high fidelity to non-natural habitats. The landscape parameters based on CORINE land cover maps and the National Grassland Inventory, were calculated for plot neighbourhoods of 4km2. Spatially constrained rarefaction curves were constructed to examine how different diversity components behave with changing structure of the surrounding landscape. Our study revealed that alpha diversity was affected by both percentage cover and diversity of different habitats in the plot neighbourhood. It increased with increasing proportion or diversity of different natural and semi-natural habitats and decreased with increasing proportion or diversity of non-natural habitats in the surrounding landscape. Beta and gamma diversities showed opposite pattern to that of alpha diversity for most analyzed factors. Alpha diversity in sub-xerophilous and mesophilous grasslands was more susceptible to changes in landscape structure than alpha diversity in xerophilous or wet grasslands. Regression trees and linear or quadratic regression models revealed that in xerophilous or wet grasslands, high alpha diversity was best predicted by a high proportion of ecologically valuable grasslands in the surroundings. In sub-xerophilous and mesophilous grasslands, the best predictor was proportion of natural and semi-natural habitats followed by the proportion of non-natural habitats. The detected pattern regarding alpha, beta and gamma diversity calculated for grassland target species did not differ from the pattern for the whole species assemblage. However, the surrounding landscape affected the number, proportion and cover of species typical of forest or non-natural habitats (including alien species) in the plots. We explain the results by the interplay of two main mechanisms: species pool and spatial mass effects. In our study, the effect of species pool on alpha diversity was stronger than the spatial mass effect. Based on differences indicated in the responses of various grassland types to the surrounding landscape structure, we suggest adoption of community type specific conservation measures
Functional traits of epiphytic lichens as potential indicators of environmental conditions in forest ecosystems
No full textSeveral experimental studies support the effectiveness of lichen diversity as an indicator of environmental change. On the contrary, the potential of functional trait values of epiphytic lichens as indicators of environmental conditions is still poorly documented. Comparisons of lichen diversity across diverse regions may be problematic due to high levels of floristic variation related to differences in environmental conditions (e.g. climate and substrate availability and types). Species' functional traits may prove to be a user-friendly tool for large-scale and long-term ecological monitoring. This paper explores the use of functional traits of epiphytic lichen species as indicators of environmental conditions: we tested the susceptibility of the three easily discernible functional traits (growth form, reproductive strategy, and photobiont type) to environmental factors related to climate, human disturbance, and stand structure. Lichen diversity and associated species traits were recorded in 14 plots within the Italian ForestBiota network representing the four main forest types of Italy. For each plot, several predictors of forest structure, climatic features, and human-related disturbances were recorded. A forward variable selection method, based on permutations and parametric tests, was used to evaluate the response of lichen diversity and functional traits. Of the three species traits, growth form was the most responsive and was a reliable indicator for evaluating and comparing the responses of epiphytic lichens to climate, human disturbance, and stand structure-related conditions in forest ecosystems across diverse regions. However, further research is needed to better clarify the potential of lichen traits in bioindication
Analisi delle trasformazioni ambientali di una zona umida sottoposta a interventi di bonifica
No full textAnalysis of the environmental transformations of a wetland subject to drainage reclamation. The “Schiavetti-Cavana” protected natural area (SAC IT3330007 “Cavana di Monfalcone”, Province of Gorizia), a relic of a wetland surviving the intensive drainage reclamation activities, represents the northernmost coastal wetland in the Mediterranean area. This peculiar environment hosts the last remnants of springs (“olle”) and the only resurgence river in the Monfalcone municipality, the river “Cavana”. The aim of this work is to perform an historical analysis on the current landscape origins, useful to support the development of management strategies consistent with the site’s conservation purpose. Four main historical moments were identified and compared: pre-reclamation, reclamation, failure of reclamation in the Cavana area and the most recent phase characterized by the spontaneous shrub encroachment in herbaceous wetland vegetatio
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