Patterns of plant beta‐diversity along elevational and latitudinal gradients in mountain forests of China

Biodiversity patterns and their underlying mechanisms have long been focal topics of study for ecologists and biogeographers. However, compared with spatial variation in species richness (α‐ and γ‐diversity), β‐diversity, or the dissimilarity of species composition between two or more sites has until recently received limited attention. In this study, we explored the large‐scale patterns of altitudinal turnover (β‐diversity) of plants in montane forests of China, based on systematic inventories of 1153 plots from 46 mountains distributed over ?30 degrees of latitude (21.9–51.7°N) and ?4100 m of altitude (160–4250 m). The β‐diversity of trees and shrubs declined significantly with increasing latitude. Along the altitudinal gradient, β‐diversity of both trees and shrubs showed non‐significant trends in most mountains. Differences in climate explained ?30.0% of the variation in tree β‐diversity (27.7, 36.5, and 26.2% for the Jaccard's, β_j, Sorenson's, β_s, and Simpson's dissimilarity, β_sim, respectively), with mean annual temperature being most important, and ≤ 10.0% of that in shrub β‐diversity (10.0, 8.2, and 7.0% for β_j, β_s, and β_sim, respectively), with annual actual evapotranspiration and annual precipitation as the main predictors. However, climatic controls of β‐diversity varied dramatically in different biogeograpical regions. The β‐diversity of trees exhibited stronger, whereas that of shrubs showed weaker, climatic patterns in temperate and arid than subtropical regions. These results suggest that mechanisms causing patterns of β‐diversity may differ between latitudinal and altitudinal gradients, and among biogeographical regions; as a result, caution should be exercised in drawing close parallels between patterns and causes of β‐diversity along latitudinal and altitudinal gradients and among regions.     

Beta‐diversity gradients of butterflies along productivity axes

Aim Several lines of evidence suggest that beta diversity, or dissimilarity in species composition, should increase with productivity: (1) the latitudinal species richness gradient is most closely related to productivity and associated latitudinal beta‐diversity relationships have been described, and (2) the scale dependence of the productivity–diversity relationship implies that there should be a positive productivity–beta‐diversity relationship. However, such a pattern has not yet been demonstrated at broad scales. We test if there is a gradient of increasing beta diversity with productivity. Location Canada. Methods Canada was clustered into regions of similar productivity regimes along three remotely sensed productivity axes (minimum and integrated annual productivity, seasonality of productivity) and elevation. The overall (β_j), turnover (β_sim) and nestedness (β_nes) components of beta diversity within each productivity regime were estimated with pairwise dissimilarity metrics and related to cluster productivity with partial linear regression and with spatial autoregression. Tests were performed for all species, productivity breadth‐based subsets (e.g. species occurring in many and a moderate number of productivity regimes), and pre‐ and post‐1970 butterfly records. Beta diversity between adjacent clusters along the productivity gradients was also evaluated. Results Within‐cluster β_j and β_sim increased with productivity and decreased with seasonality. The converse was true for β_nes. All species subsets responded similarly; however, productivity–beta‐diversity relationships were weaker for the post‐1970 temporal subset and strongest for species of moderate breadth. Between‐cluster beta diversity (β_j) and nestedness (β_nes) declined with productivity. Main conclusions As predicted, beta diversity of communities within productivity regimes was observed to increase with productivity. This pattern was driven largely by a gradient of species turnover. Therefore, beta diversity may make an important contribution to the broad‐scale gradient of species richness with productivity. However, this species richness gradient dominates regional beta diversity between productivity regimes, resulting in decreasing between‐productivity dissimilarity with productivity driven by a concurrent decline in nestedness.     

Plant strategies along mountain vegetation gradients: a test of two theories

Abstract. We test the predictions of two theories on plant strategies along vegetation gradients of a North Scandinavian mountain area, from herb-rich birch forests at 250 m. a.s.l. to the summit at 1530 m. a.s.l. According to Grime's theory, stressful physical conditions select for an adaptational syndrome called S-strategy. The theory predicts that the prevalence of S-strategic features increases monotonically from forests to high-alpine boulder fields. Alternatively, the traits that Grime regards as S-strategic can be interpreted as adaptations to high natural-grazing pressure which culminates in moderately stressful habitats: productive enough to sustain grazers but yet so barren that moderate grazer densities suffice to deplete the vegetation. The observed vegetation patterns support this alternative view. We thus suggest that Grime's triangle should be revised as to make the role of grazing as the central causal factor behind the third strategy explicit.     

Small-scale environmental heterogeneity and the analysis of species distributions along gradients

Abstract. The observed distribution of a species along an environmental gradient is strongly affected by environmental variability within a quadrat. Because a quadrat does not represent a point along an environmental gradient, but rather a range of conditions, it is likely to contain species not typically associated with the mean conditions in the quadrat. Systematic relationships exist between a species' true distribution, the observed distribution as a function of mean quadrat environment, and the frequency distribution of the environment within that quadrat. The observed species habitat breadth increases and the observed maximum abundance decreases as within-quadrat environmental heterogeneity increases. If species distributions or beta diversities are to be compared among species or coenoclines, they should be correctedforintra-quadratheterogeneity.Wederive simple corrections for environmental heterogeneity. The distributions of hardwood forest understory species along a soil acidity gradient in the North Carolina piedmont are presented as an example.     

Fish community variation along physical gradients in short streams of northern Spain and the disruptive effect of dams

Relationships between the fish community and selected habitat features were examined in a set of short temperate streams located at the northern end of the Iberian Peninsula. The fish fauna in these streams consists mostly of diadromous or estuarine species. Species richness and diversity increased with stream order, depth and width and decreased with elevation and distance from the sea. Stream order (positively) and elevation (negatively) were the two variables most highly correlated with species richness and diversity; higher order streams (order 3–4) showed greater values of species diversity than lower order ones (order 1) even when the elevation effect was removed. Addition of species in the downstream direction, but no replacement or loss was evidenced. We also compared the observed values of species diversity with those predicted from habitat features for a set of locations above unpassable dams. A great majority of the sites showed lower than predicted diversity values, which is an expected outcome for this mainly migratory fish fauna.     

Impact of free‐range pigs on mountain pastures in the Swiss Jura

Abstract. The objective of this experiment was to study the impact of free‐range pigs foraging on mountain pasture vegetation. Pigs (15 week‐old, mean weight 50 kg, n= 25) were enclosed from June to mid‐September in a 2‐ha enclosure in the Jura Mountains (Switzerland) and fed with a mixture of lactoserum and cereals. The enclosure contained four different plant communities. Eutrophic pastures on deep soil were largely overturned, but recolonization was quick and vegetation dominated by the original species. Mesotrophic pastures were less damaged on stony soil but were completely destroyed on deep soil, recovery was slow and was characterized by a shift of plant species in a more eutrophic direction. Four years were not sufficient for complete recovery. Oligotrophic calcareous pastures on shallow stony soil were not damaged. The result of this study was that extensive breeding of pigs in mountain pastures are harmful to plant species in mesotrophic pastures, and should be restricted to less sensitive plant communities, with a rotation of two or three different sites.     

阿尔卑斯山黄花茅(Anthoxanthum alpinum)沿海拔梯度的基因频率分布

在瑞士阿尔卑斯山的2个定点样地,黄花茅从森林线（海拔1700 m）到山顶（海拔2830 m）呈连续分布。在海拔梯度样带的最高和最低定样场所间的垂直距离差不多为1000 m,但2个定样场所间相距仅仅1.4 km。在所研究的3个海拔梯度样带中,3个同工酶位点（Px_1, Got_2和 Mdh_1）被观察到有统计意义的倾群变异。研究结果显示：沿海拔梯度样带的亚居群间的基因流可能太弱不足以克服自然选择的影响,后者促使对局部环境的适应。在这种情况下,温度因子至少可能作为一种主要的自然选择力起作用。     

Fish feeding guilds along a gradient of bay biotopes and coral reef depth zones

The study of fish feeding guild structure is a useful method to compare fish communities of complex marine ecosystems. Guild structure was determined in four coral reef depth zones, viz. the fringing reef at depths of 2, 5, 10, and 15 m, as well as in seven shallow-water biotopes within a single bay, viz. notches in fossil reef rock, mangroves, fossil reef boulders, seagrass beds, algal beds at a depth of 2 m, algal beds at a depth of 5 m, and the channel. The study was done in an inland bay on the Caribbean island of Curaçao, using a visual census technique. Total fish densities within the different feeding guilds varied considerably between the biotopes, and were generally higher in the reef biotopes and on the boulders than in the remaining bay biotopes. Cluster analysis revealed that the greatest dissimilarity in guild structures in terms of fish densities was that between the algal beds and all other biotopes, followed by that between the reef depth zones and other bay biotopes (notches, mangroves, seagrass beds, channel). The species composition of the guilds also differed considerably among the various biotopes. Species richness within the various guilds showed much smaller differences between the biotopes, but was generally somewhat higher in the reef biotopes. Cluster analysis of guild structures in terms of species richness revealed little dissimilarity among the various biotopes. The coral reef was dominated by omnivores and zooplanktivores, whereas the bay was dominated by zoobenthivores and herbivores. Differences in guild structure between the bay and the adjacent reef indicate differences in food availability.     

Demographic processes of upward range contraction in a long‐lived Mediterranean high mountain plant

We analyzed demographic data of a long‐lived high mountain Mediterranean plant, Silene ciliata Poirret, over a 4‐yr period. Selected populations were located at contrasting altitudes at the southernmost margin of the species (Sierra de Guadarrama, central Spain), representing a local altitudinal range at the rear edge of its overall distribution. Previous studies have suggested that differences in the reproduction and performance of individuals at upper and lower populations may have implications for population dynamics. We used matrix analysis to assess their demographic behaviour. Life Table Response Experiments were used to identify the life history stages most relevant to observed differences in population growth rates between populations. Transition matrices revealed great spatio‐temporal variability in demographic traits. Seedling recruitment was very low each year in all populations. Maximum longevity of S. ciliata individuals in the lower peripheral population was much lower compared to the central population, probably due to higher adult mortality. Population growth rate (λ) showed a declining trend at the lowest altitude and a relatively stable trend at the central population. Long‐term simulations also indicated a great risk of quasi‐extinction at the lowest population. Our results suggest that rear edge populations of S. ciliata at Sierra de Guadarrama are suffering demographic processes that may be leading to the latitudinal displacement of the species' range.     

Benthic pH gradients across a range of shelf sea sediment types linked to sediment characteristics and seasonal variability

This study used microelectrodes to record pH profiles in fresh shelf sea sediment cores collected across a range of different sediment types within the Celtic Sea. Spatial and temporal variability was captured during repeated measurements in 2014 and 2015. Concurrently recorded oxygen microelectrode profiles and other sedimentary parameters provide a detailed context for interpretation of the pH data. Clear differences in profiles were observed between sediment type, location and season. Notably, very steep pH gradients exist within the surface sediments (10–20 mm), where decreases greater than 0.5 pH units were observed. Steep gradients were particularly apparent in fine cohesive sediments, less so in permeable sandier matrices. We hypothesise that the gradients are likely caused by aerobic organic matter respiration close to the sediment–water interface or oxidation of reduced species at the base of the oxic zone (NH₄ ⁺, Mn²⁺, Fe²⁺, S^?). Statistical analysis suggests the variability in the depth of the pH minima is controlled spatially by the oxygen penetration depth, and seasonally by the input and remineralisation of deposited organic phytodetritus. Below the pH minima the observed pH remained consistently low to maximum electrode penetration (ca. 60 mm), indicating an absence of sub-oxic processes generating H⁺ or balanced removal processes within this layer. Thus, a climatology of sediment surface porewater pH is provided against which to examine biogeochemical processes. This enhances our understanding of benthic pH processes, particularly in the context of human impacts, seabed integrity, and future climate changes, providing vital information for modelling benthic response under future climate scenarios.     

Multi‐scaled drivers of rural prairie stream metabolism along human activity gradients

1. Stream metabolism is increasingly used for monitoring and assessment of the biological condition of aquatic ecosystems. However, distal environmental drivers, such as land use, are typically not well connected to the proximate controls, such as stream chemistry, that are usually invoked as driving metabolism. This is particularly true for North American prairie streams and for grassland streams worldwide. 2. Stream metabolism was measured at the outflow of 19 subcatchments of the Red River in southern Manitoba, Canada. Subcatchments represented gradients of nutrient‐producing human activities present in the region, that is, wastewater treatment (WWT), livestock production and crop cultivation. Stream metabolism was estimated at all sites using diel changes in dissolved oxygen (DO) concentration over 1 week in the middle of summer. Environmental parameters hypothesised to control stream metabolism were sampled across three spatial scales (stream reach, stream segment and catchment). Model selection using Akaike’s information criterion (AIC) was used to determine linkages between environmental parameters and measures of stream metabolism. 3. Estimated rates of metabolism were within the range of past studies of metabolism in prairie streams, although most streams had negative values of net ecosystem metabolism. However, production‐to‐respiration ratios were >0.5, at all but three sites suggesting that autochthonous production was an important source of organic matter. 4. The a priori model that best predicted gross primary production (GPP) was the intensity of nutrient‐producing human activities (i.e. WWT, livestock and crop cultivation) measured at the catchment scale. Ecosystem respiration (ER) was best predicted by the a priori model comprised of GPP, total nitrogen (TN) and total phosphorus (TP). However, model averaging revealed that prediction of ER could be improved by including riparian cover and removing TP from the model. The positive association between GPP and ER suggested that heterotrophic compartments of the ecosystem were modest contributors to variation in respiration rates. 5. Overall, this study suggests that variation of metabolism in prairie streams of southern Manitoba is controlled by human activities occurring at the catchment scale, a finding consistent with current hierarchically structured riverine paradigms. Moreover, increased understanding of the hierarchical structure of stream metabolism drivers will help to ensure that assessment results can be used more effectively to inform management strategies for prairie ecosystems.     

Abundance and diversity of birch‐feeding leafminers along latitudinal gradients in northern Europe

Latitudinal patterns in biotic interactions, including herbivory, have been widely debated during the past years. In particular, recent meta‐analysis questioned the hypothesis that herbivory increases from the poles towards the equator. Our study was designed to verify this hypothesis by exploring latitudinal patterns in abundance and diversity of birch‐feeding insect herbivores belonging to the leafminer guild in northern Europe, from 59° to 69°N. We collected branches from five mature trees of two birch species (Betula pendula and B. pubescens) at each study site (ten sites for each of five latitudinal gradients) twice per season (in early and late summer of 2008–2011) and attributed all mines found on leaves of these branches to a certain taxon of insects. Latitudinal patterns were quantified by calculating Spearman rank correlation coefficients between both abundance and diversity of leafmining taxa and latitudes of sampling sites. In general, both abundance and diversity of leafminers significantly decreased with latitude. However, we discovered pronounced variation in patterns of latitudinal changes among study years and leafminer taxa. Variation among study years was best explained by mean temperatures in July at the northern ends of our gradients. During cold years, abundance of leafminers significantly decreased with latitude, while during warm years the abundance was either independent of latitude or even increased towards the pole. In the northern boreal forests (66° to 69°N), herbivores demonstrated larger changes in densities in response to temperature variations than in the boreo‐nemoral forests (59° to 62°N). Our data suggest that climate warming will result in a stronger increase in herbivory at higher latitudes than at lower latitudes.     

Climate‐based empirical models show biased predictions of butterfly communities along environmental gradients

A better understanding of the factors that mould ecological community structure is required to accurately predict community composition and to anticipate threats to ecosystems due to global changes. We tested how well stacked climate‐based species distribution models (S‐SDMs) could predict butterfly communities in a mountain region. It has been suggested that climate is the main force driving butterfly distribution and community structure in mountain environments, and that, as a consequence, climate‐based S‐SDMs should yield unbiased predictions. In contrast to this expectation, at lower altitudes, climate‐based S‐SDMs overpredicted butterfly species richness at sites with low plant species richness and underpredicted species richness at sites with high plant species richness. According to two indices of composition accuracy, the Sorensen index and a matching coefficient considering both absences and presences, S‐SDMs were more accurate in plant‐rich grasslands. Butterflies display strong and often specialised trophic interactions with plants. At lower altitudes, where land use is more intense, considering climate alone without accounting for land use influences on grassland plant richness leads to erroneous predictions of butterfly presences and absences. In contrast, at higher altitudes, where climate is the main force filtering communities, there were fewer differences between observed and predicted butterfly richness. At high altitudes, even if stochastic processes decrease the accuracy of predictions of presence, climate‐based S‐SDMs are able to better filter out butterfly species that are unable to cope with severe climatic conditions, providing more accurate predictions of absences. Our results suggest that predictions should account for plants in disturbed habitats at lower altitudes but that stochastic processes and heterogeneity at high altitudes may limit prediction success of climate‐based S‐SDMs.     

Fish assemblages in relation to environmental gradients along a small west African coastal basin,the San Pedro River,Ivory Coast

Patterns of fish population composition were examined in the San Pedro River, Ivory Coast, in 2001 to assess whether distinct types of assemblage exist along longitudinal gradients within this small coastal basin. A total of 45 species was found: 28 in the lower and the upper courses of the river and 29 in Faé man-made lake. The environmental variables most closely associated with assemblage-level patterns were those which can be significantly modified by dam construction: transparency, conductivity, current and sampling site position on the basin. Groups were separated by means of canonical correspondence analysis and cluster analysis. Downstream assemblages were distinguished by the presence of marine and brackish water fish species and a relatively low abundance of cichlid fishes. Assemblages from Lake Faé were characterised by a predominance of cichlids.     

Eelgrass, Zostera marina, growth along depth gradients: upper boundaries of the variation as a powerful predictive tool

1200 measurements of eelgrass ( Zostera marina ) biomass, shoot density and cover along 19 depth gradients in Øresund, located between Denmark and Sweden, were analysed to characterise growth of eelgrass in relation to depth. The large data set allowed analyses of boundaries of distribution as well as of average trends. Natural variability is large in shallow water where populations are disturbed by wave action and other physical parameters. Models based on average values, therefore, did not adequately describe growth regulation by resources, and only explained a minor part (up to 30%) of the overall variation in data. In contrast, boundary functions, which describe the upper bounds of distributions, focus on the variation produced by the ultimately growth-regulating resource, and therefore provide models with high predictive power. An exponential model explained up to 90% of the variation in upper bounds of eelgrass shoot density as a function of depth and indicated that shoot density was ultimately regulated by light availability. The boundary functions demonstrated that eelgrass shoot density, biomass and cover followed markedly different patterns as functions of depth and were affected differently by the factors governing their distribution. In addition, boundary functions revealed informative spatial structures in data and illustrated whether a given general trend was caused by changes in maximum values, minimum values or both. For example, upper and lower boundaries of biomass-shoot density relations changed markedly with depth, demonstrating depth-related changes in intraspecific succession and competition patterns. Boundary functions are therefore suggested as a promising tool for analysing ultimate regulating factors of distribution and growth of organisms when large data sets are available.     

Alpine bird distributions along elevation gradients: the consistency of climate and habitat effects across geographic regions

Many species have shown recent shifts in their distributions in response to climate change. Patterns in species occurrence or abundance along altitudinal gradients often serve as the basis for detecting such changes and assessing future sensitivity. Quantifying the distribution of species along altitudinal gradients acts as a fundamental basis for future studies on environmental change impacts, but in order for models of altitudinal distribution to have wide applicability, it is necessary to know the extent to which altitudinal trends in occurrence are consistent across geographically separated areas. This was assessed by fitting models of bird species occurrence across altitudinal gradients in relation to habitat and climate variables in two geographically separated alpine regions, Piedmont and Trentino. The ten species studied showed non-random altitudinal distributions which in most cases were consistent across regions in terms of pattern. Trends in relation to altitude and differences between regions could be explained mostly by habitat or a combination of habitat and climate variables. Variation partitioning showed that most variation explained by the models was attributable to habitat, or habitat and climate together, rather than climate alone or geographic region. The shape and position of the altitudinal distribution curve is important as it can be related to vulnerability where the available space is limited, i.e. where mountains are not of sufficient altitude for expansion. This study therefore suggests that incorporating habitat and climate variables should be sufficient to construct models with high transferability for many alpine species.     

Subsidy‐stress and multiple‐stressor effects along gradients of deposited fine sediment and dissolved nutrients in a regional set of streams and rivers

1. Stream managers need to understand relationships between multiple stressors and ecological responses. We examined responses of benthic invertebrates and algae along two land‐use‐related stressor gradients of concern in running waters. Our correlative study of the consequences of augmented deposited fine sediment and nutrient concentrations was conducted in a regional set of streams and rivers monitored by a water management authority in New Zealand and incorporated a wide range of catchment geologies and stream orders. 2. We used multiple linear regression analysis and an information‐theoretic approach to select the best predictive models for our biological response variables by testing multiple competing hypotheses that include nonlinear subsidy‐stress relationships and interactive effects between the two stressors. 3. Patterns consistent with a subsidy‐stress response to increasing dissolved inorganic nitrogen concentration were found for the relative abundances of the common invertebrate genera Pycnocentrodes and Deleatidium and for the relative abundance of total individuals in the EPT orders (Ephemeroptera, Plecoptera, Trichoptera). 4. Fine sediment seemed the more pervasive stressor, apparently counteracting and overwhelming any initial subsidy effect of increased nutrients, and accounting for more of the variance in biological response variables. Relationships with high nutrient concentrations were weaker and modelled with less certainty, probably reflecting the indirect modes of action of nutrients compared to those underlying sediment effects. Nevertheless, in several cases, the models indicated that nutrients interacted synergistically with fine sediment, lending further weight to the conclusion that managers need to address both stressors to achieve the best outcomes.     

Trophodynamics of the sclerosponge Ceratoporella nicholsoni along a shallow to mesophotic depth gradient

The sclerosponge Ceratoporella nicholsoni is a hyper-calcifying high microbial abundance sponge. This sponge has been observed at high densities throughout the Caribbean in the mesophotic zone (30–150 m), as well as cryptic environments in shallow (< 30 m) depths. Given the densities of this sponge, it could play an important role in the cycling of inorganic and organic sources of carbon and nitrogen at mesophotic depths. Additionally, there is broad interest in this sponge as a tool for paleobiology, paleoclimatology and paleoceanography. As a result, it is increasingly important to understand the ecology of these unique sponges in the underexplored Caribbean mesophotic zone. Here we show that this sponge increases in abundance from shallow depths into the mesophotic zone of Grand Cayman Island. We observed no significant differences in the stable isotope signatures of δ¹⁵N and δ¹³C of sponge tissue between depths. A predictive model of sponge diet with increasing depth shows that these sponges consume dissolved organic matter of algal and coral origin, as well as the consumption of particulate organic matter consistent with the interpretation of the stable isotope data. The taxonomic composition of the sclerosponge microbiome was invariant across the shallow to mesophotic depth range but did contain the Phylum Chloroflexi, known to degrade a variety of dissolved organic carbon sources. These data suggest that the depth distribution of this sponge may not be driven by changes in trophic strategy and is potentially regulated by other biotic or abiotic factors.

     

The influence of coarse‐scale environmental features on current and predicted future distributions of narrow‐range endemic crayfish populations

1. A major limitation to effective management of narrow‐range crayfish populations is the paucity of information on the spatial distribution of crayfish species and a general understanding of the interacting environmental variables that drive current and future potential distributional patterns. 2. Maximum Entropy Species Distribution Modeling Software (MaxEnt) was used to predict the current and future potential distributions of four endemic crayfish species in the Ouachita Mountains. Current distributions were modelled using climate, geology, soils, land use, landform and flow variables thought to be important to lotic crayfish. Potential changes in the distribution were forecast by using models trained on current conditions and projecting onto the landscape predicted under climate‐change scenarios. 3. The modelled distribution of the four species closely resembled the perceived distribution of each species but also predicted populations in streams and catchments where they had not previously been collected. Soils, elevation and winter precipitation and temperature most strongly related to current distributions and represented 65–87% of the predictive power of the models. Model accuracy was high for all models, and model predictions of new populations were verified through additional field sampling. 4. Current models created using two spatial resolutions (1 and 4.5 km²) showed that fine‐resolution data more accurately represented current distributions. For three of the four species, the 1‐km² resolution models resulted in more conservative predictions. However, the modelled distributional extent of Orconectes leptogonopodus was similar regardless of data resolution. Field validations indicated 1‐km² resolution models were more accurate than 4.5‐km² resolution models. 5. Future projected (4.5‐km² resolution models) model distributions indicated three of the four endemic species would have truncated ranges with low occurrence probabilities under the low‐emission scenario, whereas two of four species would be severely restricted in range under moderate–high emissions. Discrepancies in the two emission scenarios probably relate to the exclusion of behavioural adaptations from species‐distribution models. 6. These model predictions illustrate possible impacts of climate change on narrow‐range endemic crayfish populations. The predictions do not account for biotic interactions, migration, local habitat conditions or species adaptation. However, we identified the constraining landscape features acting on these populations that provide a framework for addressing habitat needs at a fine scale and developing targeted and systematic monitoring programmes.