Ecological Requirements Of Species Research Articles

Sites and species contribution to the β-diversity of Odonata assemblages in Haiti: Implications for conservation

Understanding the ecological determinants of assemblage diversity in freshwater insects is of crucial importance for conservation biology and environmental management. This is particularly true in Haiti, where severe and ongoing environmental degradation of aquatic ecosystems is a major threat to the local invertebrate fauna. Here, using Odonates assemblages sampled from 67 waterbodies belonging to 14 different Haitian watersheds, we assessed species uniqueness (U) from both rarity based on spatial occupancy and taxonomic species distinctness (TSD), and species contribution to total β diversity (SCBD). We assessed between-site variation in species richness (SR), relative taxonomic distinctness (RTD), mean species uniqueness per site (Mean U), and the contribution of individual sites to total β diversity (LCBD), based on presence-absence data. We then examined the relationships between these variables and the physico-chemical characteristics of the sites. In total, we recorded 49 different odonate species (including two endemic species of conservation interest), belonging to 40 genera and 7 families, with a relatively high percentage (69.4%) of rare species (i.e. occurring in 10% or less of sampled water bodies). TSD was negatively correlated with spatial occupancy, while U was significantly higher in Zygopeteran species compared to Anisopteran species. SR varied among the 67 sites, ranging from 2 to 17 species, while SCBD was positively correlated with site occupancy. Differences in assemblage composition between sites were mainly due to species replacement, while only a few sites had assemblages consisting of a subset of larger assemblages found at other sites. The observed positive correlation between dissimilarity and geographic distance between sites further suggests that the turnover of species may take place over some ecological gradient and/or might be explained by species ecological requirements and limited ability to disperse. LCBD and Mean U increased with increasing altitude and decreasing temperature and conductivity, whereas SR and RTD did not. All variables were independent of pH. Overall, SR and RTD were higher in lotic than in lentic sites, and in sites with natural riparian vegetation compared to sites with anthropogenic or mixed riparian vegetation. Mean U provided a relevant index for site selection for odonates conservation in Haiti, whereas β diversity appeared to be of limited interest for this purpose. Globally, our results advocate the importance of conserving a wide diversity of waterbodies to protect Odonate diversity in Haïti, and particularly in forested areas at > 1000 m altitude.

Modern Approaches to the Monitoring of Biоdiversity (MAMBO)

EU policies, such as the EU biodiversity strategy 2030 and the Birds and Habitats Directives, demand unbiased, integrated and regularly updated biodiversity and ecosystem service data. However, efforts to monitor wildlife and other species groups are spatially and temporally fragmented, taxonomically biased, and lack integration in Europe. To bridge this gap, the MAMBO project will develop, test and implement enabling tools for monitoring conservation status and ecological requirements of species and habitats for which knowledge gaps still exist. MAMBO brings together the technical expertise of computer science, remote sensing, social science expertise on human-technology interactions, environmental economy, and citizen science, with the biological expertise on species, ecology, and conservation biology. MAMBO is built around stakeholder engagement and knowledge exchange (WP1) and the integration of new technology with existing research infrastructures (WP2). MAMBO will develop, test, and demonstrate new tools for monitoring species (WP3) and habitats (WP4) in a co-design process to create novel standards for species and habitat monitoring across the EU and beyond. MAMBO will work with stakeholders to identify user and policy needs for biodiversity monitoring and investigate the requirements for setting up a virtual lab to automate workflow deployment and efficient computing of the vast data streams (from on the ground sensors, and remote sensing) required to improve monitoring activities across Europe (WP4). Together with stakeholders, MAMBO will assess these new tools at demonstration sites distributed across Europe (WP5) to identify bottlenecks, analyze the cost-effectiveness of different tools, integrate data streams and upscale results (WP6). This will feed into the co-design of future, improved and more cost-effective monitoring schemes for species and habitats using novel technologies (WP7), and thus lead to a better management of protected sites and species.

A new method employing species‐specific thresholding identifies acoustically overlapping bats

AbstractPassive acoustic detectors are increasingly used for monitoring biodiversity, particularly for echolocating bat species (Microchiroptera). However, identification of calls collected at large scales is hindered by substantial variation within and between species, and the considerable time investment needed to manually identify acoustic data. We use acoustic data from 14 species of echolocating bats, occurring in temperate forests and woodlands of southeastern Australia to build a supervised classification model that identifies species from large acoustic datasets. Acoustic data from hand‐release (39,567) and free‐flying (8851) bat calls were used to build a predictive model, which was then validated using field‐collected calls (149,097) from the same region. We maximized the model fit per species by validating the associated confidence scores against manually identified presence and absence values. This allowed us to model the identification success of each species as a function of the confidence score. From this relationship, we set specific thresholds for accepting species identification, enabling more accurate classification of calls and identification of multiple bat species within a single acoustic recording. Including calls from manually identified free‐flying bats improved overall identification accuracy, including a 60% improvement for bats that navigate in open spaces. Assigning species‐specific thresholds achieved substantial improvements in overall model confidence, with functionally meaningful changes in the identification of species exhibiting considerable acoustic overlap in time and frequency measures. Research into the ecological requirements of species is hampered by problems with identification. Our research illustrates that internal train–test validation overestimates model accuracy particularly for species that were in low abundance or for uncommon species, which are acoustically similar to more common ones. Recognizing this, we set specific thresholds per species below which identifications were not accepted. Our method is particularly relevant in locations with high overlap in species' call parameters, which can result in false negatives in preference for species that are easier to identify because of the common practice of assigning one species per acoustic recording. This research proposes a cautious method to substantially reduce the burden of manual identification of large acoustic datasets.

Effect of Species Composition on Growth and Yield in Mixed Beech–Coniferous Stands

Research Highlights: In mixed stands, competitive and supportive relationships occur between trees, illustrated by their dendrometric characteristics. Background and Objectives: We investigated the effect of species composition on growth and yield in mixed beech–coniferous stands in the Romanian Carpathians. Materials and Methods: We selected sites with similar trophicity levels, as determined by the site mapping method. Under the same site conditions, we generated models to determine, for each species (spruce, fir, and beech), the main parameters of the site index, including mean height, dominant height, standing volume yield, and mean annual volume increment for different compositional species proportions (psp) and categories of proportions (i.e., low psp, between 10 and 50%, and high psp, ranging between 60 and 90%). Results: Overall, up to the age of 100 years, mixed stands with low psp had enhanced tree height growth, characterized by mean values 2.2% higher for spruce and 4.8% higher for fir and beech. Dominant height showed similar values, regardless of psp. Mixed stands in which the psp increased (i.e., psp > 50) were more productive, with the mean yield differences at the age of 100 years ranging from +1.7% (for fir) to +3.8% (for spruce and beech), increasing to +6% at 140 years. Conclusions: When setting management targets, the management of mixed forests should be based on an understanding of the relationship between the site, species ecological requirements, and their yield potential. Mixed stands can influence individual tree growth and stand yield through psp.

Taxonomy, Habitat Preference, and Niche Overlap of Two Arrow-Poison Flea Beetle Species of the Genus Polyclada in Sub-Saharan Africa (Coleoptera, Chrysomelidae).

Simple SummaryThe taxonomy of many African Coleoptera species is remains poorly known, and the knowledge of their ecological requirements is worse still. Starting with original data, we describe morphological differences and ecological data for two flea beetle species, Polyclada bohemani and P. pectinicornis, which traditionally have been used by the Bushmen people in sub-Saharan Africa to poison their arrows. Moreover, we evidence differences in the formations of vegetation used by these two species, which are known to occur mainly in savannah and open forest habitats. Also, we identify differently suitable areas in terms of climatic preferences, in addition to a common territory in East Africa. We also supply, for the first time, the description of the shape of the aedeagus and the spermatheca of both species, supplying important new diagnostic characters for their identification.Coupling the geographic distribution and the ecological requirements of species often supports taxonomy and biogeography. In this contribution, we update the distribution of two flea beetle species of ethno-entomological interest, Polyclada bohemani and P. pectinicornis, by analyzing original data. In addition, we supply their main morphological diagnostic characters, describing their aedeagal and spermathecal shapes for the first time. We also assess their niche differences in terms of climatic and vegetation needs, by means of ecological niche modelling and remote sensing techniques. Several new localities were identified to improve knowledge of the geographical distribution of both species. Moreover, we located a wide climatic suitability overlap in East Africa for these two flea beetle species, while in other areas they show a clear separation. Our analysis also reports that P. bohemani is associated with areas of denser tree cover than P. pectinicornis. Finally, the lectotypes of Diamphidia bohemani Baly, 1861, Clytra pectinicornis Olivier, 1791, and Diamphidia compacta Fairmaire, 1887 are here designated and the new synonymy Clytra pectinicornis Olivier = Diamphidia compacta Fairmaire syn.nov. is proposed.

East palearctic treefrog past and present habitat suitability using ecological niche models.

Ecological niche modeling is a tool used to determine current potential species’ distribution or habitat suitability models which can then be used to project suitable areas in time. Projections of suitability into past climates can identify locations of climate refugia, or areas with high climatic stability likely to contain the highest levels of genetic diversity and stable populations when climatic conditions are less suitable in other parts of the range. Modeling habitat suitability for closely related species in recent past can also reveal potential periods and regions of contact and possible admixture. In the east palearctic, there are five Dryophytes (Hylid treefrog) clades belonging to two groups: Dryophytes japonicus group: Clades A and B; and Dryophytes immaculatus group: Dryophytes immaculatus, Dryophytes flaviventris, and Dryophytes suweonensis. We used maximum entropy modeling to determine the suitable ranges of these five clades during the present and projected to the Last Glacial Maximum (LGM) and Last Interglacial (LIG) periods. We also calculated climatic stability for each clade to identify possible areas of climate refugia. Our models indicated suitable range expansion during the LGM for four clades with the exclusion of D. immaculatus. High climatic stability in our models corresponded to areas with the highest numbers of recorded occurrences in the present. The models produced here can additionally serve as baselines for models of suitability under climate change scenarios and indicate species ecological requirements.

Dinaric karst intermittent rivers harbour some rare mayflies (Insecta, Ephemeroptera)

While investigating the aquatic macroinvertebrate fauna of four intermittent Dinaric karst rivers in Croatia, we confirmed or recorded new distribution data and ecological features for several mayfly species rare in Croatian freshwater habitats: Nigrobaetis niger (Linnaeus, 1761), Procloeon pennulatum (Eaton, 1870) and Paraleptophlebia werneri Ulmer, 1920. To our knowledge, this is the first record of N. niger in intermittent lotic habitats. We discuss their substrate preferences in the studied habitats as well as their relationships with measured physico-chemical water parameters. The newly obtained results confirm that our knowledge about Croatian mayfly fauna and species ecological requirements in intermittent Mediterranean rivers is still incomplete and is increasing with systematic studies.

Assessing translocation management techniques through experimental trials: a case study of the endangered shrub Persoonia hirsuta

Translocation is commonly used in the conservation of threatened species to help mitigate the risk of local extinctions. However, translocations are often limited by knowledge of the species ecological requirements that promote persistence in the landscape. Small translocation trials with a strong experimental design can help to address species knowledge gaps and identify effective strategies for the successful establishment of a threatened species prior to implementing full‐scale planting regimes. In this study, we experimentally translocated 128 plants of the endangered Persoonia hirsuta (Proteaceae) at a dry sclerophyll mining offset in New South Wales (NSW), Australia, and investigated the effects of propagation type (seeds and vegetative cuttings), plant guards, and mulching on short‐term plant growth and survival. Transplants were impacted by herbivory and unprecedented extreme temperatures over summer 2019–2020 with 25 of the 128 plants surviving after 20 months of monitoring. Among the surviving individuals, all but one were seed propagated and 72% of survivors were protected by a plant guard. Short‐term survival and establishment of P. hirsuta translocants was increased by producing plants from seeds, and the use of plant guards with localized mulch. We also identified significantly greater root volume, projected area, and diameter for seedlings than cuttings grown plants. Our study successfully identified several key factors that should be considered for the ongoing management of P. hirsuta and vindicates the importance of small experimental trials when planning threatened plant translocations.

Extrapolation in species distribution modelling. Application to Southern Ocean marine species

Species distribution modelling (SDM) has been increasingly applied to Southern Ocean case studies over the past decades, to map the distribution of species and highlight environmental settings driving species distribution. Predictive models have been commonly used for conservation purposes and supporting the delineation of marine protected areas, but model predictions are rarely associated with extrapolation uncertainty maps.In this study, we used the Multivariate Environmental Similarity Surface (MESS) index to quantify model uncertainty associated to extrapolation. Considering the reference dataset of environmental conditions for which species presence-only records are modelled, extrapolation corresponds to the part of the projection area for which one environmental value at least falls outside of the reference dataset.Six abundant and common sea star species of marine benthic communities of the Southern Ocean were used as case studies. Results show that up to 78% of the projection area is extrapolation, i.e. beyond conditions used for model calibration. Restricting the projection space by the known species ecological requirements (e.g. maximal depth, upper temperature tolerance) and increasing the size of presence datasets were proved efficient to reduce the proportion of extrapolation areas. We estimate that multiplying sampling effort by 2 or 3-fold should help reduce the proportion of extrapolation areas down to 10% in the six studied species.Considering the unexpectedly high levels of extrapolation uncertainty measured in SDM predictions, we strongly recommend that studies report information related to the level of extrapolation. Waiting for improved datasets, adapting modelling methods and providing such uncertainy information in distribution modelling studies are a necessity to accurately interpret model outputs and their reliability.

Variation in seed traits among Mediterranean oaks in Tunisia and their ecological significance.

Oaks are the foundation and dominant tree species of most Mediterranean forests. As climate models predict dramatic changes in the Mediterranean basin, a better understanding of the ecophysiology of seed persistence and germination in oaks could help define their regeneration niches. Tunisian oaks occupy distinct geographical areas, which differ in their rainfall and temperature regimes, and are thus a valuable model to investigate relationships between seed traits and species ecological requirements. Seed morphological traits, desiccation sensitivity level, lethal freezing temperature, embryonic axis and cotyledon sugar and lipid composition, and seed and acorn germination rates at various constant temperatures were measured in Quercus canariensis, Q. coccifera, Q. ilex and Q. suber, using seeds sampled in 22 Tunisian woodlands. Only faint differences were observed for desiccation sensitivity in the oak species studied. By contrast, the species differed significantly in sensitivity to freezing, germination rates at low temperature and base temperature. Quercus ilex and Q. canariensis, which occur at high elevations where frost events are frequent, showed the lowest freezing sensitivity. A significant correlation was found between hexose contents in the embryonic axis and freezing tolerance. Significant interspecific differences in the time for seeds to germinate and the time for the radicle to pierce the pericarp were observed. The ratio of pericarp mass to acorn mass differed significantly among the species and was negatively correlated with the acorn germination rate. Quercus coccifera, which is frequent in warm and arid environments, showed the highest acorn germination rate and synchrony. Seed lethal temperature, seed germination time at low temperatures, the ratio of pericarp mass to acorn mass and the embryonic axis hexose content appeared to be key functional traits that may influence the geographical ranges and ecological requirements of Mediterranean oaks in Tunisia.

Leaf physiological and structural plasticity of two Asplenium (Aspleniaceae) species coexisting in sun and shade conditions

Background and aims – Relatively few studies have addressed the sun-shade response of fern species. Moreover, there is no information on species-specific plasticity patterns of such response, their relationship with species ecological requirements and the costs of such plasticity. The present study aims at filling these gaps by analysing the sun-shade plastic response of two Asplenium species that differ in their ecological requirements.Methods – We measured 27 leaf morphological, anatomical and physiological parameters using standard methods for A. ceterach and A. trichomanes in the field. The parameters were combined through Principal Component Analysis in order to highlight an integrated sun-shade response across species. Linear regression analysis was carried out to highlight the relationship between the calculated species plasticity patterns and the structural control on photosynthetic process.Key results – A significant degree of phenotypic plasticity was found for both species. Moreover, sun and shade leaves shared a common slope for the morpho-functional relationships reflecting no additional costs in terms of carbon assimilation. Even if the plastic responses of the two species scaled positively (R2 = 0.68, P = 4.667e‒07), A. trichomanes was characterized by a slightly higher anatomical plasticity (plasticity index = 0.19), while A. ceterach showed a higher physiological plasticity (0.60).Conclusion – A remarkable acclimation capacity for the two Asplenium species in response to different light conditions was highlighted. Nevertheless, A. ceterach seems to be more suited to cope with full sunlight conditions as compared to A. trichomanes, according to species ecological requirements.

POSITIVE RELATIONSHIPS BETWEEN HUMAN IMPACT AND BIODIVERSITY: THE CASE OF THE FIRE-BELLIED TOAD (BOMBINA BOMBINA) IN EUROPE

Habitat modification affects amphibians indirectly by reducing energy reserves and energy allocated to growth and reproduction, and by affecting population dynamics and viability. Marginal populations of amphibians in Latvia and Ukraine are particularly vulnerable. On the other hand, several studies have shown a positive relationship between human density and biodiversity, indicating that species-rich areas and human enterprises quite often co-occur. Therefore, both positive and negative correlations between human population and species richness may be expected. For a better understanding of what constitutes suitable habitat we used a habitat modeling approach, where modeling can be used for revealing species ecological requirements and relationships between the distribution of species and predictive variables, as well as the importance of each variable in model building. Here we employed maximum entropy (MaxEnt) niche modeling, as a tool to assess potential habitat suitability (HS) for amphibians in Europe, making special emphasis on anthropogenic impact. We used 2474 georeferenced point data (783 - B. bombina occurrence, and to compare results 1691 - L. vulgaris), including results of our field investigations in Latvia and Ukraine. The predictor variables used for modelling the toad species HS suitability were of climate derived from the WorldClim database (19 bioclimatic variables). Human impact was assessed by the Human Footprint (HF), produced through an overlay of a number of global data layers that represent the location of various factors presumed to exert an influence on ecosystems: human population distribution, urban areas, roads, navigable rivers, and various agricultural land uses. Using the Spearman rank correlation, a low, however statistically significant positive correlation (p<0.05), was found between the predicted HS and the HF.

BIRD FAUNA IN SECONDARY FOREST STAGES: A STUDY IN A SOUTHERN BRAZILIAN PROTECTED AREA

Environmental changes resulting from forest succession process may lead to changes in the abundance and composition of species. In each successional stage, faunal composition will depend on the structure of the habitats and the ecological requirements of each species. The effects seem to be more evident in small isolated forest fragments. In this study we recorded bird species composition and richness at different stages of secondary forest in a protected area located in a highly-fragmented region in southern Brazil. We predicted that bird species composition and richness will change according to the secondary forest stage, and will be affected by the ecological requirements of species. The study was carried out in the Mata do Rio Uruguai Teixeira Soares Municipal Park (TSP), in the northern part of the state of Rio Grande do Sul, Brazil. The park is the largest protected area in the region, with 423 ha. Representative areas of the three successional stages of secondary forest within TSP were selected, and the bird species in each area were recorded using the counting point sampling method. A total of 145 bird species were recorded in the three areas. There were differences in species composition between the areas, indicating that the structure of the bird community is directly linked to successional stages. This relationship is improved by differences in the number of birds with certain ecological traits between the areas. The size, connectivity of the forest fragments and the availability of habitats may be affecting the distribution of the avifauna in the park. Changes in the landscape may promote a restructuring of avifaunal communities, where species with certain ecological traits can be favored or excluded. The TSP, although relatively small , is important for the maintenance of bird species because it is a rare, well-preserved fragmented of the deciduous seasonal forest in the region.

First record of Demicryptochironomus (Irmakia) neglectus Reiss, 1988 in Slovakia

Here, we present the first record of Demicryptochironomus (Irmakia) neglectus Reiss, 1988 in Slovakia. Samples were taken using the Chironomid Pupal Exuviae Technique (CPET) from two reservoirs. Two pupal exuviae (out of the 500 ind. collected) were recorded in Kráľová reservoir and in one individual was found in Sĺňava reservoir (out of the total 514 ind. collected). Since the CPET method mostly allows species level identification of chironomids, its usage is helpful in discovering the real chironomid diversity of Slovakia. Moreover, it helps to define ecological requirements of species we have little information about, such as the present one.

The Need of Species Distribution Models Metadata: Using Species Distribution Model to Address Decision Making on Climate Change

Anthropogenic-induced climate change has already altered the conditions to which species have adapted locally, and consequently, shifts of occurrence areas have been previously reported (Chen et al. 2011). Anticipating the results of climate change is urgent, and using these results efficiently to guide decision-making can help to build strategies to protect species from those changes. Therefore, our objective is to propose the use of climate change impact assessments, obtained through species distribution models (SDMs), to guide decision making. The emphasis will be on data that could help determine the potentially vulnerable species and the priority areas, which could act as climate refuges, as well as wildlife corridors. SDMs are based on species occurrence points, available mainly from biological collections and observations (Franklin 2010). When combined with geospatially explicit layers of abiotic or biotic data (e. g. temperature, precipitation, land use), which defines the ecological requirements of species under study, it can generate species distribution models. These models are projected in the form of maps indicating areas where the species can find the most suitable habitats and, therefore, where one can most likely find them. To support public policies decision, the generation of robust and reliable model is an important factor. A minimum number of six occurrence points is a mandatory requirement, with non-overlapping area as a filter criteria. Unfortunatelly, in Brasil, as well as in Latin America in general, this type of data is scarce. Thus, with SDMs, four types of decision making information data regarding priority species and areas could be obtained (Fig. 1). Size of potential occurrence areas: species that have a small area of occurrence are potentially vulnerable, since they present endemism, usually living in restricted environmental conditions. In this case, any small change in environmental conditions can result in the extinction of the impacted species. Thus, this region needs to be protected. Difference between current and future area: species presenting the most significant reduction in potential areas should be prioritized by decision-makers. This measurement could be used as an indication of vulnerability. Even species that have no predicted area reduction or an increase could be prioritized in management programs due to its role in the complex interaction networks of ecosystem services, such as pollinators, seed dispersers or disease control. These species could be more resilient to network interaction changes due climate, and possibly are better able to provide their services in the extreme unfavorable climate scenarios. Areas that maintain higher species diversity in future scenarios: their protection could be prioritized in restoration and conservation programs. Especially in cases involving multiple species, those areas could be considered as climate refuges by decision-makers. Additionally, for the reconstruction and use of SDM published in peer-reviewed journals, it is necessary that all pieces of information about models, its generation, ensemble methods, data cleaning and data quality criteria applied should be available. The availability of the four above mentioned types of information can help on decision-making strategies aiming the protection of priority species and areas. In conclusion, SDMs present essential information about the present and future impacts of projected climate change and their derived data could be preserved using a standard controlled vocabulary.

Dynamic species distribution models reveal spatiotemporal habitat shifts in native range‐expanding versus non‐native invasive birds in an urban area

Urbanisation as a major driver of changes leads to the extinction of some species while others increase in abundance, especially non‐native species. Spatiotemporal distribution patterns of these successful species are likely to be shaped by their response and tolerance to urban features. This study assesses the anthropo‐ecological requirements of two co‐occurring bird species, the native range‐shifting jackdaw Corvus monedula and the non‐native invasive ring‐necked parakeet Psittacula krameri. We built yearly models over an eight‐year period using an ensemble modelling approach assessing response differences through time and between species. Predictors describing human‐made structures, socio‐ecological proxies and resources availability were extracted from temporally coincident databases. Dispersal and habitat constraints were implemented in final models to provide more realistic forecasts of species future distributions. Ensemble models evaluated with a random partition of the training dataset showed a higher accuracy than those evaluated with an independent dataset from another time period. Our results highlight temporal variations in the relative importance of predictors for both studied species. Single‐season occurrence data may thus be insufficient to characterize species ecological requirements. The ring‐necked parakeet and the jackdaw showed different responses to urban features. Jackdaws preferred the more urbanized part of the city while the distribution of parakeets was strongly positively associated with the density of exotic ornamental trees. We concluded that ring‐necked parakeet range expansion is likely to be driven by its effective ability to exploit urban resources which native species do not or under exploit, suggesting an open window of foraging opportunities. However, the jackdaw may be misled by a high cavity availability and a large amount of low‐quality anthropogenic food in the urban core. We suggest that dynamic SDMs are a critical tool not only to forecast the future expansion of invasive species but also for a better understanding of processes driving urban biodiversity persistence.

Tree-Based Methods: Concepts, Uses and Limitations under the Framework of Resource Selection Models

The use of empirical models to predict species distribution is recognized as an important tool in wildlife management. Tree-based methods gained considerable attention in the last years mostly due to their flexibility and robustness. Here, we provide an overview of tree-based methods by addressing some of their concepts, uses and limitations. For illustrative purposes, we modelled the distribution of a red deer (Cervus elaphus) population using fine-scale predictors while applying four modelling methods: three treebased methods (classification trees, random forests and boosted trees) and the generalized linear model by stepwise regression. In order to explore alternative trees and achieve the best model performance, a series of classifiers were run with different tuning parameters. The random forests and boosted trees models were the most accurate classifiers followed by classification trees and generalized linear model by stepwise regression. Despite differences in the predictive accuracy, the results of the four models were consistent with the species ecological requirements. Red deer occurred further away from disturbed areas (e.g. villages and other human settlements), agricultural fields and near shrubs and forest patches. Furthermore, the species often occurred in areas with gentle slopes, preferentially with a southern exposure. We observed that classification trees are easy to interpret but may produce unstable decision trees and unwieldy results in the presence of sharp discontinuities. We state that ensemble methods such as random forests and boosted trees are valuable tools in predicting species distributions. This study provides the necessary background for the understanding of tree-based methods, which will be of great help in further studies in ecological modelling, as it will shed light in the most appropriate technique to be used.

Manipulation of habitat isolation and area implicates deterministic factors and limited neutrality in community assembly.

Theory predicts deterministic and stochastic factors will contribute to community assembly in different ways: Environmental filters should regulate those species that establish in a particular area resulting in the ecological requirements of species being the primary driver of species distributions, while chance and dispersal limitation should dictate the likelihood of species reaching certain areas with the ecology of species being largely neutral. These factors are specifically relevant for understanding how the area and isolation of different habitats or islands interact to affect community composition. Our review of the literature found few experimental studies have examined the interactive effect of habitat area and isolation on community assembly, and the results of those experiments have been mixed. We manipulated the area and isolation of rock “islands” created de novo in a grassland matrix to experimentally test how deterministic and stochastic factors shape colonizing animal communities. Over 64 weeks, the experiment revealed the primacy of deterministic factors in community assembly, with habitat islands of the same size exhibiting remarkable consistency in community composition and diversity, irrespective of isolation. Nevertheless, tangible differences still existed in abundance inequality among taxa: Large, near islands had consistently higher numbers of common taxa compared to all other island types. Dispersal limitation is often assumed to be negligible at small spatial scales, but our data shows this not to be the case. Furthermore, the dispersal limitation of a subset of species has potentially complex flow‐on effects for dictating the type of deterministic factors affecting other colonizing species.

Focal plant species and soil factors in Mediterranean coastal dunes: An undisclosed liaison?

Understanding the response of plant species to soil factors on coastal sand dunes is critical for effective conservation of coastal habitats in the Mediterranean basin. Our main objectives were to investigate: i) the main soil factors driving species composition in a Mediterranean coastal dune environment; ii) the ecological requirements of focal plant species with respect to single soil factors; iii) whether the focal species of a given macrohabitat (including EU habitats) have similar edaphic needs. We identified 108 plots with three macrohabitats as strata (embryo dunes; mobile dunes; fixed dunes) by random stratified sampling design along the Tyrrhenian coast of central Italy in areas with a high degree of biodiversity and naturalness. Vegetation and soil data were collected in the plots.Canonical Correspondence Analysis (CCA) confirmed that soil had a main role in driving focal dune species composition as found in other Mediterranean areas and indicated that three factors (field capacity, pH and CaCO3) sufficiently explain patterns of plant species. An inverse relation between field capacity, which proves to be the most decisive feature for differences in species ecological requirements between macrohabitats, and pH was observed. Generalized Additive Models (GAMs) showed that: i) the focal species of fixed dunes have a higher probability of occurrence and response curves that overlap at high field capacity and TOC values and at low pH, showing an opposite trend with respect to the species of embryonic and mixed dunes; ii) species of mixed dunes have a probability of occurrence linked to different values of CaCO3, with Ammophila arenaria showing its optimum at high CaCO3 values. Thus our results sustain the hypothesis that dune focal species, diagnostic and characteristic of coastal dune macrohabitats, have different ecological responses with respect to soil factors. Moreover, species within the same habitat can have different ecological responses due to species competition. Data about edaphic requirements of sand dune species and modelling of their ecological responses suggests that focal dune species can be bio-indicators of soil conditions and provide useful indications for conservation, monitoring and restoration of Mediterranean coastal habitats.

The distribution of salt marsh macrophyte species in relation to physicochemical variables

The aim of this study was to explore how estuarine salt marsh macrophytes are distributed in relation to physicochemical variables. This information was examined to determine whether macrophyte species are associated with a specific range of physicochemical variables and so could be used as bioindicators. The distribution of eleven macrophyte species in fourteen estuaries across the South African temperate coast was assessed in relation to sediment (moisture content, organic content, electrical conductivity, pH and redox potential) and groundwater (electrical conductivity, salinity and depth of the groundwater) variables. A univariate and multivariate approach showed that common salt marsh species were poor bioindicators as they occurred over a broad range of values across the measured physicochemical variables (i.e. Bassia diffusa, Juncus kraussii, Sarcocornia pillansii, Sarcocornia tegetaria and Sporobolus virginicus). It is therefore suggested that rare species (Sarcocornia capensis, Frankenia pulverulenta, Poeciolepis ficoidea, S. decumbens, Plantago carnosa, Triglochin elongata, Spergularia media, Suaeda fruticosa and S. inflata) be studied further to establish relationships with physicochemical variables as these may be useful indicators to monitor responses to sea level and other environmental changes. This study provides useful data on the ecological requirements of species and habitats in response to diverse physiochemical conditions across various estuaries spanning a regional scale.