Assemblages of saproxylic beetles on large downed trunks of oak

Old living oaks (Quercus robur) are known as a very species‐rich habitat for saproxylic beetles, but it is less clear to what extent such veteran trees differ from an even rarer feature: downed trunks of large oaks. In this study, we set out to sample this habitat, using window traps, with two aims: (1) to describe the variation of assemblages among downed trunks of different type and (2) to compare beetles on downed oaks with data from veteran standing trees. The results showed that trunk volume and sun exposure better explained assemblages as well as species numbers on downed trunks than did decay stage. Furthermore, species classified as facultative saproxylic species showed weak or no differentiation among downed trunks. Species with different feeding habits showed no apparent differentiation among downed trunks. Furthermore, species composition on dead, downed oak trunks differed sharply from that of living, veteran oaks. Wood or bark feeders were more common on veterans than downed trunks, but there was no difference for those species feeding on fungi or those feeding on insects and their remains. In conclusion, for a successful conservation of the saproxylic beetle fauna it is important to keep downed oak trunks, and particularly large ones, in forest and pastures as they constitute a saproxylic habitat that differs from that of living trees.     

Variation in behavioral traits of two frugivorous mammals may lead to differential responses to human disturbance

Human activities can lead to a shift in wildlife species’ spatial distribution. Understanding the specific effects of human activities on ranging behavior can improve conservation management of wildlife populations in human‐dominated landscapes. This study evaluated the effects of forest use by humans on the spatial distribution of mammal species with different behavioral adaptations, using sympatric western lowland gorilla and central chimpanzee as focal species. We collected data on great ape nest locations, ecological and physical variables (habitat distribution, permanent rivers, and topographic data), and anthropogenic variables (distance to trails, villages, and a permanent research site). Here, we show that anthropogenic variables are important predictors of the distribution of wild animals. In the resource model, the distribution of gorilla nests was predicted by nesting habitat distribution, while chimpanzee nests were predicted first by elevation followed by nesting habitat distribution. In the anthropogenic model, the major predictors of gorilla nesting changed to human features, while the major predictors of chimpanzee nesting remained elevation and the availability of their preferred nesting habitats. Animal behavioral traits (body size, terrestrial/arboreal, level of specialization/generalization, and competitive inferiority/superiority) may influence the response of mammals to human activities. Our results suggest that chimpanzees may survive in human‐encroached areas whenever the availability of their nesting habitat and preferred fruits can support their population, while a certain level of human activities may threaten gorillas. Consequently, the survival of gorillas in human‐dominated landscapes is more at risk than that of chimpanzees. Replicating our research in other sites should permit a systematic evaluation of the influence of human activity on the distribution of mammal populations. As wild animals are increasingly exposed to human disturbance, understanding the resulting consequences of shifting species distributions due to human disturbance on animal population abundance and their long‐term survival will be of growing conservation importance.     

Hollow oaks and beetle functional diversity: Significance of surroundings extends beyond taxonomy

Veteran hollow oaks (Quercus spp.) are keystone structures hosting high insect diversity but are declining in numbers due to intensification of land use and the abandonment of traditional management. The loss of this vital habitat is resulting in a reduction of biodiversity, and this likely has consequences for ecosystem functioning, especially if functional diversity is reduced. A considerable amount of research has been done on predictors of beetle taxonomic diversity in veteran oaks, but predictors of functional diversity have remained largely unexplored. The aim of this study was to establish whether the features and surroundings of veteran oaks are related to functional diversity within three functional groups of beetles (decomposers, predators, and flower visitors) and determine whether species richness and functional diversity within the groups are dependent on the same predictors. Sampling was carried out intermittently between 2004 and 2011 on 61 veteran oaks in Southern Norway. Of the 876 beetle species that were collected, 359 were determined to be decomposers, 284 were predators, and 85 were flower visitors. Species richness and functional diversity in all groups were consistently higher in traps mounted on veteran oaks in forests than in open landscapes. However, additional predictors differed between groups, and for species richness and functional diversity. Decomposer species richness responded to tree vitality, while functional diversity responded to habitat connectivity, predator species richness responded to regrowth of shrubs while functional diversity responded to tree circumference, and flower visitor richness and functional diversity did not respond to any additional predictors. Previous studies have found that the features and surroundings of veteran oaks are important for conservation of taxonomic diversity, and the results from this study indicate that they are also important for functional diversity within multiple functional groups.     

Sugarcane and Eucalyptus plantation equally limit the movement of two forest‐dependent understory bird species

Habitat fragmentation results in landscape configuration, which affects the species that inhabit it. As a consequence, natural habitat is replaced by different anthropogenic plantation types (e.g. pasture, agriculture, forestry plantations and urban areas). Anthropogenic plantations are important for biodiversity maintenance because some species or functional groups can use it as a complementary habitat. However, depending on plantation permeability, it can act as a barrier to the movement of organisms between habitat patches, such as forest fragments, reducing functional connectivity for many species. Anthropogenic plantations are becoming the most common land use and cover type in the Anthropocene and biodiversity conservation in fragmented landscapes requires information on how different plantation types affect the capacity of the species to move through the landscape. In this study, we evaluated the influence of the type and structure of plantations on the movement of two forest‐dependent understory bird species – plain antvireo (Dysithamnus mentalis) and flavescent warbler (Myiothlyps flaveola) – within a highly fragmented landscape of Atlantic Forest hotspot. Knowing that forestry plantation is assumed to be more permeable to dependent forest bird species than open ones, we selected six study areas containing a forest fragment and surrounding plantation: three with sugarcane plantation and three with Eucalyptus sp. plantation. We used playback calls to stimulate the birds to leave forest fragments and traverse the plantations. Control trials were also carried out inside the forest fragments to compare the distances crossed. We observed that individuals moved longer distances inside forest than between plantation types, which demonstrate that plantations do constrict the movements of both species. The two plantation types equally impeded the movements of the species, suggesting the opposite of the general assumption that forestry plantations are more permeable. Our results indicate that, for generalist species, plantation type does not matter, but its presence negatively impacts movement of these bird species. We highlight that plantations have negative influences on the movements of common bird species, and discuss why this is important when setting conservation priorities.     

Towards a core set of landscape metrics for biodiversity assessments: A case study from Dadia National Park,Greece

Spatial heterogeneity has an important influence on a wide range of ecological patterns and processes, and many landscape metrics in GIS environment are used to facilitate the investigation of the relation between landscape structure and biodiversity. Data reduction analyses have been applied to tackle the problem of highly correlated indices, but valid landscape predictors for fine scale Mediterranean forest-mosaics are still missing. Therefore, we analyzed the landscape structure of Dadia National Park, Greece, a Mediterranean forest landscape of high biodiversity, characterized by pine, oak and mixed woodland. By distinguishing nine land cover classes, 119 variables were computed and factor analysis was applied to detect the statistical dimensions of landscape structure and to define a core set of representative metrics. At landscape level, diversity of habitats, fragmentation and patch shape and at class level dominance of mixed forest and the gradient from one pure forest type to another turned out to be the crucial factors across three different scales. Mapping the encountered dimensions and the representative metrics, we detected that the pattern of landscape structure in Dadia National Park was related to dominating habitat types, land use, and level of protection. The evaluated set of metrics will be useful in establishing a landscape monitoring program, to detect the local drivers of biodiversity, and to improve management decisions in Dadia NP and similar mosaic-landscapes.     

Molecular and morphological support for a Florida origin of the Cuban oak

Aim The origins of the Cuban biota are of long‐standing interest in biogeography, and the source of a small live oak (Quercus series Virentes) population on Cuba remains unresolved. Based on morphological evidence, previous authors have hypothesized a Florida origin from either Q. geminata or Q. virginiana or both; a Mexican origin from Q. oleoides; or a hybrid origin from both sources. We use molecular data and taxonomically informative leaf morphology to identify the source species and timing of colonization. Location Cuba, Central America, Mexico and the south‐eastern United States. Methods  We collected representative samples of Cuban oaks and each putative source species and genotyped each sample at 12 nuclear microsatellites and two chloroplast DNA sequences. We estimated population structure using a Bayesian clustering analysis and F‐statistics, pairwise migration rates among taxa, and divergence time using an isolation‐with‐migration model. We measured seven leaf traits and conducted an analysis of similarity (ANOSIM) to determine which putative source species was most similar to Cuban oaks. Results Cuban oak contains one chloroplast DNA haplotype, which is common in southern Florida. Bayesian clustering analysis of microsatellites revealed that the Cuban oak forms a distinct and pure population cluster, and F‐statistics showed that Cuban oaks are differentiated least from Q. virginiana and most from Q. geminata. Migration rates were highest out of Cuba to Q. oleoides. Molecular diversity, the ratio of allelic richness to allele size range, and effective population size of the Cuban oak were relatively low, suggesting a founder effect. Divergence time estimates fell entirely within the Pleistocene (628–6 ka), considering a range of mutation rates and generation times. Cuban oaks were morphologically most similar to Q. virginiana and least similar to Q. geminata. Main conclusions Molecular and morphological data support a Pleistocene dispersal of Q. virginiana from Florida to Cuba, followed by isolation and divergence, then limited dispersal and introgression from Cuba to Q. oleoides in Central America. Birds could have dispersed acorns to Cuba during a glacial period when sea levels were low. These results highlight the varied origin of the Cuban biota and the possible role of Pleistocene glaciations in the establishment of temperate taxa in the tropics.     

Landscape genetics in a changing world: disentangling historical and contemporary influences and inferring change

Landscape genetics seeks to determine the effect of landscape features on gene flow and genetic structure. Often, such analyses are intended to inform conservation and management. However, depending on the many factors that influence the time to reach equilibrium, genetic structure may more strongly represent past rather than contemporary landscapes. This well‐known lag between current demographic processes and population genetic structure often makes it challenging to interpret how contemporary landscapes and anthropogenic activity shape gene flow. Here, we review the theoretical framework for factors that influence time lags, summarize approaches to address this temporal disconnect in landscape genetic studies, and evaluate ways to make inferences about landscape change and its effects on species using genetic data alone or in combination with other data. Those approaches include comparing correlation of genetic structure with historical versus contemporary landscapes, using molecular markers with different rates of evolution, contrasting metrics of genetic structure and gene flow that reflect population genetic processes operating at different temporal scales, comparing historical and contemporary samples, combining genetic data with contemporary estimates of species distribution or movement, and controlling for phylogeographic history. We recommend using simulated data sets to explore time lags in genetic structure, and argue that time lags should be explicitly considered both when designing and interpreting landscape genetic studies. We conclude that the time lag problem can be exploited to strengthen inferences about recent landscape changes and to establish conservation baselines, particularly when genetic data are combined with other data.     

Modelling Mediterranean oak palaeolandscapes using the MaxEnt model algorithm: The case of the NE Iberia under the Middle Holocene climatic scenario

The Mediterranean Basin is a global biodiversity hotspot, and oak tree species play an important role in it. Since the beginning of the Holocene (∼11.4 kyr BP), the distribution of forests has not occurred uniformly, resulting in diverse types of vegetation landscapes. In this study, we used a maximum entropy algorithm (MaxEnt) to obtain the ecological niche model (ENM) of two sub-Mediterranean oak species, Quercus pubescens Willd. (pubescent oak) and Quercus ilex subsp. ilex (holm oak), both in the present day in the Iberian Peninsula and within a Middle Holocene (8.2–4.2 kyr BP) climatic scenario in the NE Iberian Peninsula. Moreover, we used the locations of Neolithic archaeological sites containing anthracological data to analyze the relationship between human occupations and oak habitats. Our results suggest that the two oaks have responded differently to the climatic conditions that have occurred, and show changes in both potential distributions. The palaeolandscape vegetation map shows a denser vegetation cover in the lowlands and a more open landscape in the highlands, with a higher dominance of Quercus pubescens in the septentrional areas, while Quercus ilex was more restricted to certain coastal areas. Temperature and precipitation factors, mainly seasonal climatic conditions, have had a greater impact on the distribution of vegetation than other factors. We found a good overlap between the ENM of the two oaks and the locations of the Neolithic sites analysed, and determined that the distribution of Neolithic archaeological sites is not random. The Neolithic populations in the study area depended heavily on the resources of the deciduous and evergreen sub- Mediterranean forest, although they also exploited the resources of the mountain pine forest. Neolithic sites distribution suggests that Neolithic human groups were aware of the potential of forests and probably gathered woody resources in their surroundings.     

Using historical ecology to understand patterns of biodiversity in fragmented agricultural landscapes

Aim To enhance current attempts to understand biodiversity patterns by using an historical ecology approach to highlight the over‐riding influence of land‐use history in creating past, current and future patterns of biodiversity in fragmented agricultural landscapes. Methods We develop an integrative conceptual framework for understanding spatial and temporal variations in landscape patterns in fragmented agricultural landscapes by presenting five postulates (hypotheses) which highlight the important role of historical, anthropogenic disturbance regimes. We then illustrate each of these postulates with examples drawn from fragmented woodlands in agricultural areas of south‐eastern Australia, and discuss these findings in an international context. Location examples are drawn from agricultural areas in south‐eastern Australia. Results We conclude that there is limited potential to refine our understanding of patterns of biodiversity in human‐modified landscapes based on traditional concepts of island biogeography, or simple assumptions of ongoing destruction and degradation. Instead, we propose that in agricultural landscapes that were largely cleared over a century ago: (1) present‐day remnant vegetation patterns are not accidental, but are logically arrayed due to historic land‐use decisions, (2) historic anthropogenic disturbances have a major influence on current ecosystem conditions and diversity patterns, and (3) the condition of remnant ecosystems is not necessarily deteriorating rapidly. Main conclusions An historical ecology approach can enhance our understanding of why different species and ecosystem states occur where they do, and can explain internal variations in ecological conditions within remnant ecosystems, too often casually attributed to the ‘mess of history’. This framework emphasizes temporal changes (both past and future) in biotic patterns and processes in fragmented agricultural landscapes. Integration of spatially and temporally explicit historical land‐use information into ecological studies can prove extremely useful to test hypotheses of the effects of changes in landscape processes, and to enhance future research, restoration and conservation management activities.     

Influence of canopy openness,ungulate exclosure,and low‐intensity fire for improved oak regeneration in temperate Europe

Failed oak regeneration is widely reported in temperate forests and has been linked in part to changed disturbance regimes and land‐use. We investigated if the North American fire–oak hypothesis could be applicable to temperate European oaks (Quercus robur, Quercus petraea) using a replicated field experiment with contrasting canopy openness, protection against ungulate browsing (fencing/no fencing), and low‐intensity surface fire (burn/no burn). Survival, relative height growth (RGR_H), browsing damage on naturally regenerated oaks (≤300 cm tall), and changes in competing woody vegetation were monitored over three years. Greater light availability in canopy gaps increased oak RGR_H (p = .034) and tended to increase survival (p = .092). There was also a trend that protection from browsing positively affected RGR_H (p = .058) and survival (p = .059). Burning reduced survival (p < .001), nonetheless, survival rates were relatively high across treatment combinations at the end of the experiment (54%–92%). Most oaks receiving fire were top‐killed and survived by producing new sprouts; therefore, RGR_H in burned plots became strongly negative the first year. Thereafter, RGR_H was greater in burned plots (p = .002). Burning altered the patterns of ungulate browsing frequency on oaks. Overall, browsing frequency was greater during winter; however, in recently burned plots summer browsing was prominent. Burning did not change relative density of oaks, but it had a clear effect on competing woody vegetation as it reduced the number of individuals (p < .001) and their heights (p < .001). Our results suggest that young, temperate European oaks may respond similarly to fire as their North American congeners. However, disturbance from a single low‐intensity fire may not be sufficient to ensure a persistent competitive advantage—multiple fires and canopy thinning to increase light availability may be needed. Further research investigating long‐term fire effects on oaks of various ages, species‐specific response of competitors and implications for biodiversity conservation is needed.     

Landscape dynamics in Mediterranean oak forests under global change: understanding the role of anthropogenic and environmental drivers across forest types

The Mediterranean region is projected to be extremely vulnerable to global change, which will affect the distribution of typical forest types such as native oak forests. However, our understanding of Mediterranean oak forest responses to future conditions is still very limited by the lack of knowledge on oak forest dynamics and species‐specific responses to multiple drivers. We compared the long‐term (1966–2006) forest persistence and land cover change among evergreen (cork oak and holm oak) and deciduous oak forests and evaluated the importance of anthropogenic and environmental drivers on observed changes for Portugal. We used National Forest Inventories to quantify the changes in oak forests and explored the drivers of change using multinomial logistic regression analysis and an information theoretical approach. We found distinct trends among oak forest types, reflecting the differences in oak economic value, protection status and management schemes: cork oak forests were the most persistent (62%), changing mostly to pines and eucalypt; holm oak forests were less persistent (53.2%), changing mostly to agriculture; and deciduous oak forests were the least persistent (45.7%), changing mostly to shrublands. Drivers of change had distinct importance across oak forest types, but drivers from anthropogenic origin (wildfires, population density, and land accessibility) were always among the most important. Climatic extremes were also important predictors of oak forest changes, namely extreme temperatures for evergreen oak forests and deficit of precipitation for deciduous oak forests. Our results indicate that under increasing human pressure and forecasted climate change, evergreen oak forests will continue declining and deciduous oak forests will be replaced by forests dominated by more xeric species. In the long run, multiple disturbances may change competitive dominance from oak forests to pyrophytic shrublands. A better understanding of forest dynamics and the inclusion of anthropogenic drivers on models of vegetation change will improve predicting the future of Mediterranean oak forests.     

乡村景观生物多样性研究进展

乡村景观是一种人文和自然共生的复合生态系统, 为生物多样性的维持提供了支持。目前, 中国传统乡村地区生物多样性的维持正面临着农业集约化、人工林树种单一化、非农业用地急剧扩张及生态传承机制解体等复杂多样的威胁, 亟待展开深入研究。本文在总结乡村景观生物多样性相关概念及特征的基础上, 通过文献分析概括了国际乡村景观生物多样性的热点研究方向, 包括农业集约化下的生物多样性管理、区域尺度乡村景观与生物多样性的协同关系、局地尺度不同乡村景观类型的物种多样性及乡村景观中的生物文化多样性, 进一步梳理了国内在相关研究方向上的主要进展并指出研究不足。在此基础上提出未来研究展望, 包括突出生物文化多样性特征、加强多时空尺度分析、深化动态维持机制研究、推进生物多样性研究在乡村生态景观规划中的全过程应用等建议。     

Inferring relationships between native plant diversity and Lonicera japonica in upland forests in north Mississippi,USA

Question: Do anthropogenic disturbances interact with local environmental factors to increase the abundance and frequency of invasive species, which in turn exerts a negative effect on native biodiversity? Location: Mature Quercus‐Carya and Quercus‐Carya‐Pinus (oak‐hickory‐pine) forests in north Mississippi, USA. Methods: We used partial correlation and factor analysis to investigate relationships between native ground cover plant species richness and composition, percent cover of Lonicera japonica, and local and landscape‐level environmental variables and disturbance patterns in mature upland forests. We directly measured vegetation and environmental variables within 34 sampling subplots and quantified the amount of tree cover surrounding our plots using digital color aerial photography. Results: Simple bivariate correlations revealed that high species richness and a high proportion of herbs were associated with low Lonicera japonica cover, moist and sandy uncompacted soils, low disturbance in the surrounding landscape, and periodic prescribed burning. Partial correlations and factor analysis showed that once we accounted for the environmental factors, L japonica cover was the least important predictor of composition and among the least important predictors of species richness. Hence, much of the negative correlation between native species diversity and this invasive species was explained by soil texture and local and landscape‐level land‐use practices. Conclusions: We conclude that negative correlations between the abundance of invasive species and native plant diversity can occur in landscapes with a gradient of human disturbance, regardless of whether there is any negative effect of invasive species on native species.     

Landscape simplification increases vineyard pest outbreaks and insecticide use

Diversifying agricultural landscapes may mitigate biodiversity declines and improve pest management. Yet landscapes are rarely managed to suppress pests, in part because researchers seldom measure key variables related to pest outbreaks and insecticides that drive management decisions. We used a 13‐year government database to analyse landscape effects on European grapevine moth (Lobesia botrana) outbreaks and insecticides across c. 400 Spanish vineyards. At harvest, we found pest outbreaks increased four‐fold in simplified, vineyard‐dominated landscapes compared to complex landscapes in which vineyards are surrounded by semi‐natural habitats. Similarly, insecticide applications doubled in vineyard‐dominated landscapes but declined in vineyards surrounded by shrubland. Importantly, pest population stochasticity would have masked these large effects if numbers of study sites and years were reduced to typical levels in landscape pest‐control studies. Our results suggest increasing landscape complexity may mitigate pest populations and insecticide applications. Habitat conservation represents an economically and environmentally sound approach for achieving sustainable grape production.     

Human and non-human determinants of forest composition in southern Spain: evidence of shifts towards cork oak dominance as a result of management over the past century

Aims Both human and non‐human determinants have shaped Mediterranean forest structure over the last few millennia. The effects of recent human activities on forest composition, however, remain poorly understood. We quantified changes in forest composition during the past century in the mixed forests of Quercus suber (cork oak) and Q. canariensis (Algerian oak), and explored the effects of forest management and environmental (climate, topography) factors on forest structure at various spatial and temporal scales. Location Mountains north of the Strait of Gibraltar (southern Spain). Methods First, we quantified 20th‐century changes in species composition from a series of inventories in nine mixed forests (c. 40,000 ha), and examined them in terms of the management practices and environmental conditions. Second, we analysed present‐day Q. suber and Q. canariensis stand structure along environmental gradients at two spatial scales: (1) that of the forest landscape (c. 284 ha), combining local inventories and topographic variables and using a digital elevation model; and (2) regional (c. 87,600 km²), combining data from the Spanish Forest Inventory for the Andalusia region and estimates of climatic variables. Results Historical data indicate anthropogenic changes in stand composition, revealing a sharp increase in the density of cork oaks over the last century. Forest management has favoured this species (for cork production) at the expense of Q. canariensis. The impact of management is imprinted on the present‐day forest structure. The abundance of both species increases with annual mean precipitation, and they coexist above 800 mm (the minimum threshold for Q. canariensis). Quercus suber dominates in most of the stands, and species segregation in the landscape is associated with the drainage network, Q. canariensis being clearly associated with moister habitats near streams. Main conclusions Our study quantitatively exemplifies a recent human‐mediated shift in forest composition. As a result of forest management, the realized niche of the cork oak has been enlarged at the expense of that of Q. canariensis, providing further evidence for humans as major drivers of oak forest composition across the Mediterranean. Recent regeneration problems detected in Q. suber stands, a reduced demand for wood products, conservation policies, and climate change augur new large‐scale shifts in forest composition.     

The challenges that spatial context present for synthesizing community ecology across scales

Accurately characterizing spatial patterns on landscapes is necessary to understand the processes that generate biodiversity, a problem that has applications in ecological theory, conservation planning, ecosystem restoration, and ecosystem management. However, the measurement of biodiversity patterns and the ecological and evolutionary processes that underlie those patterns is highly dependent on the study unit size, boundary placement, and number of observations. These issues, together known as the modifiable areal unit problem, are well known in geography. These factors limit the degree to which results from different metacommunity and macro‐ecological studies can be compared to draw new inferences, and yet these types of comparisons are widespread in community ecology. Using aquatic community datasets, we demonstrate that spatial context drives analytical results when landscapes are sub‐divided. Next, we present a framework for using resampling and neighborhood smoothing to standardize datasets to allow for inferential comparisons. We then provide examples for how addressing these issues enhances our ability to understand the processes shaping ecological communities at landscape scales and allows for informative meta‐analytical synthesis. We conclude by calling for greater recognition of issues derived from the modifiable areal unit problem in community ecology, discuss implications of the problem for interpreting the existing literature, and identify tools and approaches for future research.     

Ecological filtering or random extinction? Beta‐diversity patterns and the importance of niche‐based and neutral processes following habitat loss

Although both niche‐based and neutral processes are involved in community assembly, most models on the effects of habitat loss are stochastic, assuming neutral communities mainly affected by ecological drift and random extinction. Given that habitat loss is considered the most important driver of the current biodiversity crisis, unraveling the processes underlying the effects of habitat loss is critical from both a theoretical and an applied perspective. Here we unveil the importance of niche‐based and neutral processes to species extinction and community assembly across a gradient of habitat loss, challenging the predictions of neutral models. We draw on a large dataset containing the distribution of 3653 individuals of 42 species, representing 35% of the small mammal species of the Atlantic Forest hotspot, obtained in 68 sites across three continuously‐forested landscapes and three adjacent 10 000‐ha fragmented landscapes differing in the amount of remaining forest (50%, 30% and 10%). By applying a null‐model approach, we investigated β‐diversity patterns by detecting deviations of observed community similarity from the similarity between randomly assembled communities. Species extinction following habitat loss was decidedly non‐random, in contrast to the notion that fragmented communities are mainly driven by ecological drift. Instead, habitat loss led to a strong biotic homogenization. Moreover, species composition changed abruptly at the same level of landscape‐scale habitat loss that has already been associated with a drastic decline in species richness. Habitat loss, as other anthropogenic disturbances, can thus be seen as a strong ecological filter that increases (rather than decreases) the importance of deterministic processes in community assembly. As such, critical advances for the development of conservation science lie on the incorporation of the relevant niche traits associated with extinction proneness into models of habitat loss. The results also underscore the fundamental importance of pro‐active measures to prevent human‐modified landscapes surpassing critical ecological thresholds.     

Species pools in cultural landscapes – niche construction,ecological opportunity and niche shifts

This paper discusses the ecology of species that were favoured by the development of the cultural landscape in central and NW Europe beginning in the Neolithic and the Bronze Age, with a focus on mechanisms behind species responses to this landscape transformation. A fraction of species may have maintained their realized niches from the pre‐ agricultural landscape and utilized similar niches created by the landscape transformation. However, I suggest that many species responded by altering their niche relationships, and a conceptual model is proposed for this response, based on niche construction, ecological opportunity and niche shifts. Human‐mediated niche construction, associated with clearing of forests and creation of pastures and fields promoted niche shifts towards open habitats, and species exploited the ecological opportunity provided by these created environments. This process was initially purely ecological, i.e. the new habitats must have been included in the original fundamental niche of the species. Two other features of human‐mediated niche construction, increased interconnectivity and increased spatial stability of open habitats, resulted in species accumulating in the habitats of the constructed landscape. As a consequence, selection processes were initiated favouring traits promoting fitness in the constructed landscape. This process implied a feed‐back to niche shifts, but now also including evolutionary changes in fundamental niches. I briefly discuss whether this model can be applied also to present‐day anthropogenic impact on landscapes. A general conclusion is that ecological and evolutionary changes in species niches should be more explicitly considered in modeling and predictions of species response to present‐day landscape and land‐use changes.     

Variable history of land use reduces the relationship to specific habitat requirements of a threatened aquatic insect

The hutchinsonian realized niche of a species is the most common tool for selecting the actions needed when restoring habitats and establishing conservation areas of species. However, defining the realized niche of a species is problematic due to variation across spatial and temporal scales. In this study we tested the hypothesis that habitat parameters defining the realized niche of a species can be derived from a regional study and that national changes in land use influence the perception of the realized niche across different landscapes. We described the realized habitat niche of the threatened dragonfly Leucorrhinia pectoralis, in four Estonian landscapes which all have undergone more than 20 years of habitat degradations. We recorded the presence/absence of L. pectoralis and measured 7 habitat variables for 140 lakes and ponds located in one restored and three un-restored landscapes. Lake size and proportion of short riparian vegetation were significantly positive parameters determining the presence of L. pectoralis across landscape types. The species was much more habitat specific in the restored landscape, with larger influence of other habitat parameters. Our data suggest that the realized niche of the species in the un-restored landscapes was constrained by the present-day habitats. The study demonstrate that if a species realized niche is derived from local distribution patterns without incorporating landscape history it can lead to an erroneous niche definition. We show that landscape restoration can provide knowledge on a species’ habitat dependencies before habitat degradation has occurred, provided that restoration mitigation reflects the former landscape characteristics.     

Weather underground: Subsurface hydrologic processes mediate tree vulnerability to extreme climatic drought

Drought extent and severity have increased and are predicted to continue to increase in many parts of the world. Understanding tree vulnerability to drought at both individual and species levels is key to ongoing forest management and preparation for future transitions in community composition. The influence of subsurface hydrologic processes is particularly important in water‐limited ecosystems, and is an under‐studied aspect of tree drought vulnerability. With California's 2013–2016 extraordinary drought as a natural experiment, we studied four co‐occurring woodland tree species, blue oak (Quercus douglasii), valley oak (Quercus lobata), gray pine (Pinus sabiniana), and California juniper (Juniperus californica), examining drought vulnerability as a function of climate, lithology and hydrology using regional aerial dieback surveys and site‐scale field surveys. We found that in addition to climatic drought severity (i.e., rainfall), subsurface processes explained variation in drought vulnerability within and across species at both scales. Regionally for blue oak, severity of dieback was related to the bedrock lithology, with higher mortality on igneous and metamorphic substrates, and to regional reductions in groundwater. At the site scale, access to deep subsurface water, evidenced by stem water stable isotope composition, was related to canopy condition across all species. Along hillslope gradients, channel locations supported similar environments in terms of water stress across a wide climatic gradient, indicating that subsurface hydrology mediates species’ experience of drought, and that areas associated with persistent access to subsurface hydrologic resources may provide important refugia at species’ xeric range edges. Despite this persistent overall influence of the subsurface environment, individual species showed markedly different response patterns. We argue that hydrologic niche segregation can be a useful lens through which to interpret these differences in vulnerability to climatic drought and climate change.