Persistence at distributional edges: Columbia spotted frog habitat in the arid Great Basin,USA

A common challenge in the conservation of broadly distributed, yet imperiled species is understanding which factors facilitate persistence at distributional edges, locations where populations are often vulnerable to extirpation due to changes in climate, land use, or distributions of other species. For Columbia spotted frogs (Rana luteiventris) in the Great Basin (USA), a genetically distinct population segment of conservation concern, we approached this problem by examining (1) landscape‐scale habitat availability and distribution, (2) water body‐scale habitat associations, and (3) resource management‐identified threats to persistence. We found that areas with perennial aquatic habitat and suitable climate are extremely limited in the southern portion of the species’ range. Within these suitable areas, native and non‐native predators (trout and American bullfrogs [Lithobates catesbeianus]) are widespread and may further limit habitat availability in upper‐ and lower‐elevation areas, respectively. At the water body scale, spotted frog occupancy was associated with deeper sites containing abundant emergent vegetation and nontrout fish species. Streams with American beaver (Castor canadensis) frequently had these structural characteristics and were significantly more likely to be occupied than ponds, lakes, streams without beaver, or streams with inactive beaver ponds, highlighting the importance of active manipulation of stream environments by beaver. Native and non‐native trout reduced the likelihood of spotted frog occupancy, especially where emergent vegetation cover was sparse. Intensive livestock grazing, low aquatic connectivity, and ephemeral hydroperiods were also negatively associated with spotted frog occupancy. We conclude that persistence of this species at the arid end of its range has been largely facilitated by habitat stability (i.e., permanent hydroperiod), connectivity, predator‐free refugia, and a commensalistic interaction with an ecosystem engineer. Beaver‐induced changes to habitat quality, stability, and connectivity may increase spotted frog population resistance and resilience to seasonal drought, grazing, non‐native predators, and climate change, factors which threaten local or regional persistence.     

生态保护区外斑块对景观连接度的影响评价

快速的城市化过程带来的生境斑块破碎化及损失会影响物种迁移、捕食等生态活动,对生物多样性构成威胁。然而,现有生态保护区可能无法覆盖其内生物的必要活动范围。生态保护区外的生境斑块对于维持生态过程也具有重要作用,因此识别生态保护区外的关键斑块并加以保护非常重要。以北京市延庆区为研究区,划分两种生境斑块,即核心生境斑块和潜在生境斑块,并基于图论构建生境网络。考虑地表覆盖类型、坡度、人类活动等因素构建生境阻力面。结合未来土地利用类型变化的模拟,研究城市化过程对区域生境网络和景观连接度的影响,选用CLUE-S模型模拟土地利用类型变化的格局。结合生境斑块特征和未来城市土地利用变化情况设计了3种未来生境变化情景。利用连接概率指数(PC)和网络连接度变化率(dI)评价不同生境变化情景下生态保护区外潜在生境斑块的景观连接度重要性,判断保护优先顺序,并分析景观格局变化对不同迁移能力物种的影响。结果表明：生态保护区外的全部潜在生境斑块对维持生境整体景观连接度有最大2.15%的影响,单个潜在生境斑块对维持景观连接度有最大0.28%的影响。此外,景观格局及其变化对不同迁移能力物种的影响差异显著,因此需针对保护物种和城市生境特征设计保护方案,研究区需要优先保护大中型斑块和位于关键位置的小型斑块。为了满足对生物多样性保护的需求,建议在区分生境斑块保护优先顺序时考虑生境斑块对景观连接度的贡献和城市化扩展过程的压力。研究为城市生物多样性保护和生境管理提供了方法参考。     

Elucidating the significance of spatial memory on movement decisions by African savannah elephants using state–space models

Spatial memory facilitates resource acquisition where resources are patchy, but how it influences movement behaviour of wide-ranging species remains to be resolved. We examined African elephant spatial memory reflected in movement decisions regarding access to perennial waterholes. State–space models of movement data revealed a rapid, highly directional movement behaviour almost exclusively associated with visiting perennial water. Behavioural change point (BCP) analyses demonstrated that these goal-oriented movements were initiated on average 4.59 km, and up to 49.97 km, from the visited waterhole, with the closest waterhole accessed 90% of the time. Distances of decision points increased when switching to different waterholes, during the dry season, or for female groups relative to males, while selection of the closest waterhole decreased when switching. Overall, our analyses indicated detailed spatial knowledge over large scales, enabling elephants to minimize travel distance through highly directional movement when accessing water. We discuss the likely cognitive and socioecological mechanisms driving these spatially precise movements that are most consistent with our findings. By applying modern analytic techniques to high-resolution movement data, this study illustrates emerging approaches for studying how cognition structures animal movement behaviour in different ecological and social contexts.     

Alpine glacial relict species losing out to climate change: The case of the fragmented mountain hare population (Lepus timidus) in the Alps

Alpine and Arctic species are considered to be particularly vulnerable to climate change, which is expected to cause habitat loss, fragmentation and—ultimately—extinction of cold‐adapted species. However, the impact of climate change on glacial relict populations is not well understood, and specific recommendations for adaptive conservation management are lacking. We focused on the mountain hare (Lepus timidus) as a model species and modelled species distribution in combination with patch and landscape‐based connectivity metrics. They were derived from graph‐theory models to quantify changes in species distribution and to estimate the current and future importance of habitat patches for overall population connectivity. Models were calibrated based on 1,046 locations of species presence distributed across three biogeographic regions in the Swiss Alps and extrapolated according to two IPCC scenarios of climate change (RCP 4.5 & 8.5), each represented by three downscaled global climate models. The models predicted an average habitat loss of 35% (22%–55%) by 2100, mainly due to an increase in temperature during the reproductive season. An increase in habitat fragmentation was reflected in a 43% decrease in patch size, a 17% increase in the number of habitat patches and a 34% increase in inter‐patch distance. However, the predicted changes in habitat availability and connectivity varied considerably between biogeographic regions: Whereas the greatest habitat losses with an increase in inter‐patch distance were predicted at the southern and northern edges of the species’ Alpine distribution, the greatest increase in patch number and decrease in patch size is expected in the central Swiss Alps. Finally, both the number of isolated habitat patches and the number of patches crucial for maintaining the habitat network increased under the different variants of climate change. Focusing conservation action on the central Swiss Alps may help mitigate the predicted effects of climate change on population connectivity.     

Do elephants prevent other African herbivores from using waterholes in the dry season?

In some African protected areas, concerns have arisen about the influence of locally high elephant numbers on other forms of biodiversity. In arid and semi-arid savannas, surface-water resources are scarce and agonistic interactions between elephants and other herbivores have been reported at waterholes, yet surprisingly very little is known about the impact of elephants on the use of waterholes by other herbivores. Here, we test whether when there are elephants at a waterhole, other herbivores (1) do not change their drinking behaviour; (2) spend shorter time around the water because they are disturbed by elephants’ presence and consequently have to leave the waterhole area probably without having met their water requirements, or (3) spend more time around the water probably owing to an increase in vigilance activities or because the presence of elephants may signal safety from predators. Results show that all species spend longer time around water when there are elephants at the waterhole, although the difference is not large. Consequently, this study strongly suggests that elephants do not prevent other herbivores from drinking (time at waterholes is not shortened when elephants are around). Further, if the additional time spent to drink is linked to an increased vigilance, the difference is not large, and hence unlikely to affect the population dynamics of other herbivores.     

Variation in tree growth sensitivity to moisture across a water-limited forest landscape

Water availability acts as a major constraint on productivity in many sub-humid forest regions. Precipitation can be an important limiting factor for tree growth in such areas, but the strength of the relationship can vary by habitat and species, as well as with tree size and local hydrology. We quantified the influence of past weather conditions on the growth of two conifer species (Pinus contorta and Picea glauca) across a water-limited forest landscape in western Canada. The two species differ in moisture requirements and are segregated across a local elevational gradient, and so we expected them to exhibit different sensitivities to precipitation. We also expected that larger trees and those more distant from creeks would have a stronger response to precipitation. A hierarchical Bayesian model fit to the annual ring widths of 387 trees showed that historical precipitation from 1951 to 2016 had a positive overall effect on radial growth. The magnitude of precipitation effects on radial tree growth varied with creek proximity (a proxy for the soil moisture provided by an elevated water table in the valley bottom) and tree size. Precipitation had a greater positive influence on the growth of larger P. glauca trees, as well as individuals of both species at far and intermediate distances from creeks. Precipitation had a weaker but still positive effect on P. glauca trees growing close to creeks. Tree growth rates may change with the predicted greater inter-annual variability of precipitation under climate change, but the magnitude of these responses appear to vary by species, size, and creek proximity. Overall changes in tree growth are expected to be relatively small as trees are well-adapted to cope with the variation in water availability across a moisture-limited landscape.     

Interference competition and temporal niche shifts: elephants and herbivore communities at waterholes

Scarcity of resources may result in high levels of animal aggregation; interference competition can occur in such a scenario and play a role in resource acquisition. Here, we test the hypothesis that animals could minimize interference competition by shifting their temporal niches in relation to competitors. In Hwange National Park, Zimbabwe, we monitored waterholes in order to study agonistic interactions between elephants and other herbivore species. We also used a long-term data set from a yearly survey of waterhole attendance by herbivores to evaluate the influence of the presence of elephants on the use of waterholes by other herbivore species. Our results show that in drier years, waterholes are crowded with elephants early in the afternoon. In general, the species most affected by interference competition with elephants shift their temporal niches at the waterholes, thus maintaining a constant temporal overlaps with elephants. The species less affected by interference competition with elephants show no temporal niche shifts and increase their temporal overlap with elephants at waterholes, as predicted from a noncompetition hypothesis. This study provides evidence that interference competition with a behaviorally dominant large species influences the temporal niches of smaller species, and suggests that the potential costs associated with interference between elephants and other herbivores at waterholes are linked to shifts in diurnal activities rather than interactions and water acquisition itself.     

Range shifting on a fragmented landscape

Projected responses of species' to climate change have so far included few of the factors that are important determinants of species' distributions within its range. In this paper we utilise a spatially explicit cellular lattice, colonisation–extinction model to investigate the effect of habitat loss, fragmentation and species characteristics on range shifting in response to climate change. Contrary to the predictions of patch occupancy in static climate models we show that fragmentation can have a positive effect on species survival when species have high colonisation rates. For species with low colonisation rates aggregative behaviours prevent success on fragmented landscapes at high levels of habitat loss, and range shifting is more successfully achieved where habitat is correlated. At levels of habitat loss near the extinction threshold, less fragmented landscapes can facilitate range shifting even for the best colonisers. We discuss how imposing a climate window may reduce percolation routes and have implications for the area of usable habitat at any given level of habitat availability. We demonstrate the importance of landscape structure for range shifting dynamics and argue that management of reserve networks needs to consider the requirements of species with different life history characteristics.     

自然保护区气候变化风险及其评估——以达里诺尔国家级自然保护区为例

从基于风险管理应对气候变化的基本理论框架和气候变化对我国自然保护区管理的挑战出发,明确了自然保护区气候变化风险的涵义,并以达里诺尔自然保护区鸟类及其赖以生存的水体、草地、林地、沼泽地生境为研究对象,对达里诺尔自然保护区气候变化风险及其变化趋势进行评估和预测.结果表明: 1997—2010年,达里诺尔自然保护区及其水体、草地、林地、沼泽地生境的气候变化风险均呈明显的波动性变化趋势,1999、2001、2005、2008年保护区及其4类生境和2002、2004年沼泽地生境均处于风险状态;与2010年相比,情景A、B、C下2020、2030年保护区及其4类生境的气候变化风险均有所增强;各类生境的气候变化风险存在显著差异,其中,沼泽地生境的气候变化风险较为突出,与其对气候变化的敏感性和丰富的鸟类分布密切相关;人类对水资源、草地资源的过度利用会加剧气候变化对自然保护区的不利影响及其对应的生态风险.总体上,气候变化风险在达里诺尔自然保护区已经显现,气候变化风险管理有助于保持并增强自然保护区的生物多样性保护功能.     

Following the water? Landscape‐scale temporal changes in bat spatial distribution in relation to Mediterranean summer drought

Understanding how the spatial distribution of ecological resources shapes species’ diversity and abundance in human‐modified landscapes is a central theme in conservation biology. However, studies often disregard that such patterns may vary over time, thereby potentially missing critical environmental constraints to species persistence. This may be particularly important in highly mobile species such as bats, which are able to track temporal variations in spatial resource distribution. Here we test the hypothesis that bats in Mediterranean landscapes are strongly affected by the progressive reduction in water availability during the seasonal summer drought. We analyzed the effects of landscape composition and structure on bat diversity and activity, during pregnancy, lactation, and postlactation periods, and identified the most influential variables within and across periods. Water bodies showed the strongest positive effect on bats, followed by riparian habitats and areas with steeper (>30%) slopes. However, while during pregnancy, there were only small landscape effects, these increased during lactation and postlactation, highlighting a progressively stronger association with water habitats during the summer drought. The spatial projection of habitat models showed that the landscape distribution of bat diversity and activity hotspots changed markedly over time. During pregnancy, the spatial pattern of hotspot distribution was weakly defined, while during lactation and particularly postlactation, there was a concentration of hotspots along permanently flowing watercourses. Our study highlights that permanently flowing watercourses are critical for bat conservation in Mediterranean landscapes, calling for measures to counteract their ongoing degradation due in particular to climate change, water abstraction and damming. More generally, our study underlines the importance of considering the temporal dimension in habitat selection studies, without which there is the risk of overlooking the importance of habitats that are key for species persistence only at certain times of the year.     

A proposed strategy for maintaining mature forest habitat in Tasmania's wood production forests

Mature forests have structural habitat features that can take hundreds of years to develop, and large reserves alone are unlikely to ensure conservation of the species that rely on these features. This paper outlines a proposed new approach to managing mature forest features, the ‘mature habitat management approach’, in areas outside of reserves. The objective was to maintain a network of current and future mature forest habitat distributed across the landscape. The approach is designed to complement the existing reserve network and management actions and is tenure‐blind. Spatial information on the availability of mature forest habitat at the local (1‐km radius) and landscape (5‐km radius) scales is used for decisions on retention within a 1‐km radius of a harvest area, to reach the minimum target of 20% and 30% retention of mature forest at the local and landscape spatial scales, respectively. We believe this approach could contribute to meeting the conservation needs of many species that require mature forest features for refuge and breeding in Tasmania and elsewhere.     

Climate and land use changes will degrade the configuration of the landscape for titi monkeys in eastern Brazil

Land use changes have profound effects on populations of Neotropical primates, and ongoing climate change is expected to aggravate this scenario. The titi monkeys from eastern Brazil (Callicebus personatus group) have been particularly affected by this process, with four of the five species now allocated to threatened conservation status categories. Here, we estimate the changes in the distribution of these titi monkeys caused by changes in both climate and land use. We also use demographic‐based, functional landscape metrics to assess the magnitude of the change in landscape conditions for the distribution predicted for each species. We built species distribution models (SDMs) based on maximum entropy for current and future conditions (2070), allowing for different global circulation models and contrasting scenarios of glasshouse gas concentrations. We refined the SDMs using a high‐resolution map of habitat remnants. We then calculated habitat availability and connectivity based on home‐range size and the dispersal limitations of the individual, in the context of a predicted loss of 10% of forest cover in the future. The landscape configuration is predicted to be degraded for all species, regardless of the climatic settings. This include reductions in the total cover of forest remnants, patch size and functional connectivity. As the landscape configuration should deteriorate severely in the future for all species, the prevention of further loss of populations will only be achieved through habitat restoration and reconnection to counteract the negative effects for these and several other co‐occurring species.     

African Elephants Adjust Speed in Response to Surface-Water Constraint on Foraging during the Dry-Season

Most organisms need to acquire various resources to survive and reproduce. Individuals should adjust their behavior to make optimal use of the landscape and limit the costs of trade-offs emerging from the use of these resources. Here we study how African elephants Loxodonta africana travel to foraging places between regular visits to waterholes. Elephant herds were tracked using GPS collars during two consecutive dry seasons in Hwange National Park, Zimbabwe. We segmented each individual movement track at each visit to water to define foraging trips, and then used trip-level statistics to build an understanding of movement strategies. Travel speed within these individually-consistent movement bouts was also analyzed to understand if speed was better linked to distance to water or progression in the trip over time. We found that elephants went further from water when drinking less often, which could result from a trade-off between drinking and foraging in less depleted, far from water, places. Speed increased towards the beginning and the end of the trips, and was also greater than observed during the wet season, suggesting that elephants were trying to save time. Numerous short trips traveled at greater speed, particularly when commuting to a different waterhole, was tentatively explained by the inability to drink at specific waterholes due to intra-specific interference. Unexpectedly elephants did not always minimize travel time by drinking at the closest waterhole, but the extra distance traveled remained never more than a few kilometers. Our results show how individuals may adjust movement behavior to deal with resource trade-offs at the landscape scale. We also highlight how behavioral context, here progression in the trip, may be more important than spatial context, here distance to water, in explaining animal movement patterns.     

Importance of spatio–temporal connectivity to maintain species experiencing range shifts

Climate change can affect the habitat resources available to species by changing habitat quantity, suitability and spatial configuration, which largely determine population persistence in the landscape. In this context, dispersal is a central process for species to track their niche. Assessments of the amount of reachable habitat (ARH) using static snap-shots do not account, however, for the temporal overlap of habitat patches that may enhance stepping-stone effects. Here, we quantified the impacts of climate change on the ARH using a spatio–temporal connectivity model. We first explored the importance of spatio–temporal connectivity relative to purely spatial connectivity in a changing climate by generating virtual species distributions and analyzed the relative effects of changes in habitat quantity, suitability and configuration. Then, we studied the importance of spatio–temporal connectivity in three vertebrate species with divergent responses to climate change in North America (grey wolf, Canadian lynx and white-tailed deer). We found that the spatio–temporal connectivity could enhance the stepping-stone effect for species predicted to experience range contractions, and the relative importance of the spatio–temporal connectivity increased with the reduction in habitat quantity and suitability. Conversely, for species that are likely to expand their ranges, spatio–temporal connectivity had no additional contribution to improve the ARH. We also found that changes in habitat amount (quantity and suitability) were more influential than changes in habitat configuration in determining the relative importance of spatio–temporal connectivity. We conclude that spatio–temporal connectivity may provide less biased and more realistic estimates of habitat connectivity than purely spatial connectivity.     

Landscape connectivity and the role of small habitat patches as stepping stones: an assessment of the grassland biome in South America

Connectivity losses lead to a reduction of the amount of habitat resources that can be reached and used by species, and hence to a decline in the ranges and abundance of multiple taxa. Despite the recognized important role of small habitat patches for many species inhabiting fragmented landscapes, their potential contribution as stepping stones for maintaining overall landscape connectivity has received less attention. Using connectivity metrics based on a graph-theoretic approach we (i) quantified the connectivity of grassland patches in a sector of the Pampa region in Argentina, using a range of dispersal distances (from 100 to 10,000 m) representative of the scale of dispersal of different species; (ii) identified the most relevant patches for maintaining overall connectivity; and (iii) studied the importance of small patches (defined for different area thresholds of 5, 20, and 50 ha) as connectivity providers in the landscape. Although grassland patches were in general poorly connected at all distances, some of them were critical for overall connectivity and were found to play different crucial roles in the patch network. The location of small patches in the grassland network allowed them to function as stepping stones, yielding significant connectivity gains for species that move large distances (>5000 m) for the three area thresholds considered. Thus, under the spatial pattern of the studied landscape, species that move long distances would benefit from stepping stones, while less mobile organisms would benefit from, and mostly rely on the largest patches. We recommend that future management activities should (i) aim at preserving the grassland patches with the highest potential as stepping stones to promote landscape-level connectivity; and (ii) pay more attention to the conservation of key small patches, particularly given that usually they are those more vulnerable to land clearing for agriculture.     

Isolation determines patterns of species presence in highly fragmented landscapes

In fragmented landscapes, changes in habitat availability, patch size, shape and isolation may affect survival of local populations. Proposing efficient conservation strategies for such species relies initially on distinguishing the particular effects of those factors. To address these issues, we investigated the occurrence of 3 bird species in fragmented Brazilian Atlantic Forest landscapes. Playback techniques were used to collect presence/absence data of these species inside 80 forest patches, and incidence models were used to infer their occupancy pattern from landscape spatial structure. The relative importance of patch size, shape and surrounding forest cover and isolation was assessed using a model selection approach based on maximum likelihood estimation. The presence of all species was in general positively affected by the amount of surrounding habitat and negatively affected by inter‐patch distances. The joint effects of patch size and the surrounding landscape characteristics were important determinants of occupancy for two species. The third species was affected only by forest cover and mean patch isolation. Our results suggest that local species presence is in general more influenced by the isolation from surrounding forests than by patch size alone. We found evidence that, in highly fragmented landscapes, birds that can not find patches large enough to settle may be able to overcome short distances through the matrix and include several nearby patches within their home‐ranges to complement their resource needs. In these cases, patches must be defined as functionally connected habitat networks rather than mere continuous forest segments. Bird conservation strategies in the Atlantic forest should focus on increasing patch density and connectivity, in order to implement forest networks that reduce the functional isolation between large remnants with remaining core habitat.     

Functional connectivity as an indicator for patch occupancy in grassland specialists

Habitat specialists living in metapopulations are sensitive to habitat fragmentation. In most studies, the effects of fragmentation on such species are analyzed based on Euclidean inter-patch distances. This approach, however, ignores the role of the landscape matrix. Recently, therefore, functional distances that account for the composition of the landscape surrounding the habitat patches have been used more frequently as indicators for patch occupancy. However, the performance of functional and non-functional connectivity measures in predicting patch occupancy of such species has never been compared in a multi-species approach.Here we evaluate the effect of habitat connectivity on the patch occupancy of 13 habitat specialists from three different insect orders (Auchenorrhyncha, Lepidoptera, Orthoptera) in fragmented calcareous grasslands. In order to calculate functional distances we used four different sets of resistance values and rankings. We then modelled species’ occurrence using both Euclidean and functional (based on least-cost modelling) inter-patch distances as predictors.We found that functional connectivity measures provided better results than the non-functional approach. However, a functional connectivity measure that was based on very coarse land-cover data performed even better than connectivity measures that were based on much more detailed land-use data.In order to take into account possible effects of the landscape matrix on patch occupancy by habitat specialists, future metapopulation studies should use functional rather than Euclidean distances whenever possible. For practical applications, we recommend a ‘simple approach’ which requires only coarse land-cover data and in our study performed better than all other functional connectivity measures, even more complex ones.     

Modelling land use changes for landscape connectivity: The role of plantation forestry and highways

Landscape connectivity is a key aspect for the maintenance of biodiversity and ecosystem viability. Nowadays, the competition between economic development and nature conservation is intense. In most territories natural vegetation is being replaced by exotic tree plantations, which have a better performance in terms of timber productivity but often, a lower ecological value. We evaluated potential natural forest connectivity improvement in the Cantabria region (Northern Spain) through two main actions: protection of environmentally valuable forest areas, and reforestation with indigenous species of those patches of exotic plantation trees with a particularly important role for the connectivity of the forest network. We established a variety of scenarios to calculate least cost paths, considering the presence or absence of plantation forestry and highways to examine connectivity. Then, we applied two habitat availability indices (integral index of connectivity and probability of connectivity) attending to different dispersal distances. Our analyses show a great potential for improving connectivity using plantation forests in the natural forest network, and a dramatic impact of the highway in the north–south connectivity of the study area. Based on these results, we identified those patches of plantation forest and natural forest that are more important for the maintenance of overall landscape connectivity, and propose their protection or conversion through reforestation. The final proposed network constitutes a larger and better connected natural forested landscape than the existing one.     

Reproductive output in Mediterranean shrubs under climate change experimentally induced by drought and warming

The effects of climate change on plant reproductive performance affects the sequence of different plant reproductive stages from flowering to seed production and viability, as well as the network of relationships between them. These effects are expected to respond to different components of climate change, such as temperature and water availability, and may be sensitive to differences in species phenology.We used long-term experimental drought and warming treatments to study the effect of climate change on flower production, fruit and seed-set, seed size and seed germination rate (proportion of germinating seeds) in three Mediterranean shrubs coexisting in a coastal shrubland.Larger plants produced significantly more flowers in all three species, and higher fruit-set in Dorycnium pentaphyllum. Flower production was reduced in drought and warming treatments in the spring-flowering species D. pentaphyllum and Helianthemum syriacum, but not in the autumn–winter species Erica multiflora, which increased flowering in the warming treatment. However, the drought treatment eventually resulted in a decreased seed-set in E. multiflora. Structural equation modelling revealed strong correlations between the sequential reproductive stages. Specifically, flower density in inflorescences determined seed-set in H. syriacum, and seed size and germination rate in E. multiflora. Nevertheless, the relevance of relationships between reproductive traits changed between climatic treatments: in D. pentaphyllum a direct relationship between plant size and seed size only arised in the drought treatment, while in H. syriacum climate treatments resulted in a stronger relationship between the number of flowers and seed-set.This experimental study shows the ability of changing climatic variables to determine the reproductive sequential process of woody species. We show that several parameters of the reproductive performance of some Mediterranean species are affected by drought and warming treatments simulating climate change, highlighting the importance of changes in both water availability and temperature, and the sequential relationship between reproductive stages. Phenological patterns also contribute to species’ differential responses to climatic change, due to the relationship of these patterns with resource availability, environmental conditions and plant–pollinator interactions.     

Habitat connectivity analysis for conservation implications in an urban area

In urbanized areas, habitat loss and fragmentation resulting from urban growth and human activities may threaten the biological diversity. It is essential to maintain the connectivity in some isolated and fragmented habitat patches. In 2005, the orchard-based conservation with the legal binding was implemented in Shenzhen to mitigate the ecological threats from forest destruction and to protect the ecological diversity. It is critical to evaluate the efficiency of orchard habitat from the species’ perspective for providing the reference for the habitat management. Based on graph-theoretic methods, we compared the habitats with or without orchards and evaluated the contribution of orchards to the whole network connectivity and its three fractions (intra, flux and connector), and then analyzed the species that could benefit the most from the habitat supplement. We identified the important landscape elements for serving the prioritized conservation. The results showed that orchard-based conservation was an efficient way in maintaining the functional connectivity, which mainly contributed to the intrapatch connectivity and species dispersal flux. The value of orchard incorporation was strongly related with the dispersal ability of threatened species. Our findings indicated that the orchard conservation would be more valuable for species with relatively weak dispersal abilities. We showed the key patches and links that most contribute to uphold functional connectivity in the reserve network. We believe that the assessment based on habitat functional connectivity can effectively serve the practical guidelines of habitat conservation and management in urban areas.