Degree Of Habitat Fragmentation Research Articles

There is room for everyone: Invasion credit cannot be inferred from the species–area relationship in fragmented forests

AbstractQuestionsLand use change, habitat fragmentation and biological invasion represent major drivers of global change that strongly interact to alter ecosystems. Following the breaking apart of forests into smaller fragments or the afforestation of former agricultural lands, biodiversity experiences drastic changes due to species loss and turnover over time. This leads to two important outcomes, namely extinction debt and invasion (colonization) credit, which both reflect the inertia of the system's response to environmental changes. Our study investigated the following questions: Is it possible to infer invasion credit from species–area relationship (SAR) residuals both for native and alien plants? Is there any trend linked with the degree of habitat fragmentation through time? LocationSomme, Oise and Aisne departments, northern France.MethodsWe analyzed the pattern of SARs' residuals for native and alien vascular plant species separately across nine sets of forest fragments that differ by the landscape matrix they are embedded in (i.e., open field, bocage, forest), while considering plant richness, area and age of the 355 forest patches.ResultsThe relationship between alien and native SARs’ residuals is positive across all landscapes, suggesting a lack of invasion credit. Instead, these results support the “rich get richer” hypothesis, that is a high environmental heterogeneity allows colonization by new species, be they native or alien. Interestingly, the relationship between alien and native residuals depends upon fragment age (i.e., time since patch creation) in the most intensively managed landscapes (i.e., open fields). In the latter, recent forest patches are more prone to alien invasion, as a likely consequence of increased alien propagule pressure (i.e., more sources and vectors for alien plants), increased forest invasibility (i.e., disturbance‐induced environmental heterogeneity), and decreased matrix permeability (i.e., natives are more dispersal‐limited than aliens).ConclusionsOur study provides new insights into alien species ecology, by showing that (i) it is not possible to infer “invasion credit” from the SAR's residuals; (ii) the invasion rate by alien species in forest fragments increases with their native species richness, and (iii) this relationship depends upon patch age in intensively managed landscapes.

Identification of Spartina alterniflora habitat expansion in a Suaeda salsa dominated coastal wetlands

Spartina alterniflora (S. alterniflora) was introduced into China in the 1980s to control coastal erosion. However, it has significant negative impacts on coastal wetlands by encroaching on the habitat of native plant communities, which has seriously threatened coastal wetland function and biodiversity maintenance. The core area of the Migratory Bird Sanctuaries along the Coast of Yellow Sea-Bohai Gulf of China was taken as the study area and GF-2 remote sensing images from 2017, 2019 and 2020 were selected in this study. By using U-Net, this study extracted habitat information, identified the variation in habitat pattern, investigated interspecific competition and the characteristics of habitat type shifts. The results indicated that the U-Net model showed excellent classification performance, with the highest F1-score and MIoU. The habitat of S. alterniflora expanded and increased from 3,920 to 4,350 hm2 between 2017 and 2020. The habitat of Suaeda salsa (S. salsa) continuously fragmented and had been reduced to 1,414 hm2 by 2020. The degree of habitat fragmentation in the core area was strengthened and heterogeneity was enhanced. Moreover, while the competition between S. alterniflora and Phragmites australis (P. australis) was intensifying, both encroached on the habitat of S. salsa, which aggravated the reduction and fragmentation of the habitat of S. salsa, causing the loss of food and habitat of red-crowned cranes and further threatening biodiversity maintenance and ecosystem stability. These results can offer new insights on the habitat competitive mechanism among native plant communities and alien invasive species in the coastal wetland under global warming and anthropogenic influences.

广西黑叶猴栖息地景观格局破碎化分析及其对种群的影响

黑叶猴（Trachypithecus francoisi）是仅分布于喀斯特石山生境的珍稀濒危灵长类动物。由于非法捕杀和人类活动干扰，其种群数量正在急剧减少。同时，随着森林砍伐和土地开垦的加速，其栖息地严重破碎化。因此，了解栖息地破碎化对黑叶猴种群的影响对于保护这一珍稀濒危物种具有重要意义。基于遥感影像、土地利用数据以及黑叶猴种群调查数据，通过Fragstats软件开展广西黑叶猴栖息地景观破碎化分析，并通过相关性和多元逐步回归分析，探讨了景观格局对广西黑叶猴种群数量的影响。结果表明：（1）广西黑叶猴栖息地呈现破碎化严峻、斑块形状复杂化、斑块团聚程度较弱且分散化的现象；栖息地以林地景观占据重要优势，但人为景观的干扰十分强烈；在不同地区中，生境破碎化程度、人为干扰强度以及景观配置均呈现不同的特征，其中扶绥地区人为干扰最为强烈，德保地区的景观块数破碎化程度较为严重，而龙州地区的人为干扰程度最小，其森林景观最为聚集。（2）蔓延度指数、平均斑块分维指数、林地面积、林地斑块大小、裸岩面积和裸岩面积比重等景观指数与黑叶猴种群数量有显著正向关系，Shannon多样性指数则是显著负向关系；而耕地面积、耕地面积占比、居民地面积以及居民地面积占比等具有人为干扰性质的景观指数对黑叶猴种群数量没有显著相关性。（3）多元逐步回归分析表明，林地面积的大小是影响广西黑叶猴种群数量关键因子，其次是平均斑块分维指数。因此，在保护规划工作中应该根据黑叶猴分布区的森林覆盖率、破碎化程度、生境连通度以及景观配置情况进行生态恢复，同时也应结合保护区的实际情况进行调整。;The François' langur (Trachypithecus francoisi) is an endangered primate species that is restricted to habitats characterized by karst topography. Because of illegal hunting and disturbance by human activities, its population decreases dramatically. Moreover, its habitats become severely fragmented as results of the acceleration of deforestation and land reclamation. Therefore, it is important to understand the influence of habitat fragmentation on the François' langur population, which will provide key information for the conservation of this rare and endangered species. In this study, based on remote sensing images, land-use data, and the François' langur population survey data, we conducted landscape fragmentation analysis of the François' langur habitat in Guangxi by Fragstats software. We also explored the influences of landscape pattern on the population of François' langurs in Guangxi by correlation analysis and multiple stepwise regression analysis. The results showed that the landscape pattern of the François' langur habitats in Guangxi presented severe fragmentation, complex patch shapes, weak patch aggregation, and decentralization. The woodland landscape still made an important contribution to the langur habitats, but the anthropogenic landscape interference was very strong. There were different characteristics in the degree of habitat fragmentation, the intensity of human disturbance, and the distribution of landscapes in different areas. The Fusui area had the strongest human disturbance, and the Debao area had a more severe degree of fragmentation, while the Longzhou area had the least anthropogenic disturbance and its forest landscape was the most aggregated. There were significantly and positively relationships between Contagion Index, Mean Patch Fractal Dimension, Woodland Area, Woodland Patch Size, Bare Rock Area and Bare Rock Percentage of Landscape and the population of François' langurs, whereas Shannon Diversity Index was significantly and negatively related to the population of François' langurs. However, there was no significant correlation between artificial landscape indices, such as Curtivated Land Area, Percentage of Curtivated Land Residential Land Area, Percentage of Residential Land Area and the population of the François' langur. Based on the results of the multiple stepwise regression analysis, Woodland Area was key factors influencing the population of the François' langur in Guangxi,followed by Mean Patch Fractal Dimension. Therefore, the managers should carry out different types of ecological restoration according to the forest coverage, fragmentation degree, and landscape configuration in the distribution area of the François' langur. At the same time, managers should develop a reliable conservation plan based on the actual situation of the nature reserve.

Fine‐scale population fragmentation of a grassland butterfly Plebejus argyrognomon inhabiting agricultural field margin and riverbank in rural landscapes

AbstractEvaluating the spatial genetic structure of rare species is important because it could provide information on the degree of habitat fragmentation and effective population size that are necessary for conservation planning. We examined the genetic structure of the grassland butterfly Plebejus argyrognomon that has severely declined in recent decades using single nucleotide polymorphisms obtained by the MIG‐seq method. The study region was in the southern Ina Basin located in central Japan, where P. argyrognomon inhabits grasslands in agricultural field margin as well as in riverbank. We found a positive association between genetic and geographic distances, but the pattern was nonlinear, with little change in genetic distance above 12 km. The genetic differentiation was considerable, as demonstrated by FST and Structure. Moreover, genetic diversity was positively associated with habitat connectivity index, suggesting severe genetic drift in isolated populations. Comparing two habitat types, the genetic structure tended to be similar among agricultural field margin populations while dissimilar among riverbank populations, suggesting frequent gene flow in the former. Coupled with the presence of many habitat patches in agricultural field margin, we consider that agricultural field margin populations in the northern part of the study sites appear valuable to ensure long‐term persistence of the regional P. argyrognomon population.

近40年野骆驼历史分布区土地利用变化及生境破碎化驱动因素

野骆驼是中亚地区重要的迁徙物种，历史上完整、连续的野骆驼栖息地目前已成为孤岛状。为了解野骆驼历史分布区受人类活动的影响，明确造成其历史分布区破碎化的驱动因素，研究选取土地利用和道路两个因素，通过对近40年来的野骆驼历史分布区土地利用变化和动态度分析，以及道路密度和影响域计算，定量评估野骆驼历史分布区景观格局，以期为野骆驼栖息地整体连通性的改善，避免或缓解线性基础设施建设对野骆驼栖息地的影响提供科学的建议。结果表明：（1）近40年，野骆驼历史分布区内以未利用土地和草地为主体的格局保持不变，尤其是沙地、戈壁为主的未利用土地始终占比很大（>80%）；（2）野骆驼历史分布区范围内道路密度为0.0410 km/km²，但道路的阻隔作用明显，野骆驼当前分布区呈3个孤岛的格局与道路隔离形成的景观格局是一致的；（3）野骆驼历史分布区斑块数为914个，西部历史分布区斑块数为78个，远低于中部的373个和东部的463个，斑块数和平均斑块面积两个景观指数表明西部的栖息地破碎化程度比中部和东部栖息地要低；（4）从最大斑块指数来看，残存的大面积、无路区斑块是当前野骆驼种群得以存续的庇护所。根据当前的景观格局和破碎化状况，西部分布区和中部分布区间通过实施科学的栖息地连通和廊道建设规划，将极有可能实现两个孤立种群的交流连通，中部分布区和东部分布区间种群已基本无连通的可能。建议将更多的保护资源和努力投入到西部和中部分布区种群的维持和连通。在未来的道路规划建设和布局中，要考虑道路规划和建设对野骆驼最小生境面积的影响，并且要将影响评估尺度放大到整个野骆驼历史分布区的尺度上考虑道路的阻隔作用。;The wild camel (Camelus ferus) is an important migratory species in Central Asia. Unfortunately, its historically intact and continuous distribution has become three isolated regions of habitat (western, middle, and eastern region) as a result of human activity. In an effort to better clarify the driving factors of fragmentation, this study calculated the dynamic index of land use change from 1980 to 2018. Specifically, we evaluated the effects of land use via calculation of road density and road-effect zone to evaluate the impact of roadways. The results showed that:(1) in the past 40 years, unused land and grassland in the species' historical distribution range has remained unchanged, especially unused land dominated by sand which accounted for over 80% of the wild camel's historical distribution range. (2) Road density in the historical distribution range was 0.0410 km/km², but road barrier effects were large and consistent with the three isolated habitat regions in the current distribution area. (3) The total number of habitat patches in the historical distribution range of the wild camel was 914. These were comprised of 78 patches in the western region, which was much lower than the 373 and 463 patches in the middle and eastern regions, respectively. The number of patches and mean patch size indicated that the degree of habitat fragmentation in the western region was lower than that of the middle and eastern regions. (4) The largest patch index showed that the remaining large and roadless patches were critical for the survival of the current wild camel population. Present-day landscape fragmentation patterns suggest that the western and middle regions could be connected with corridor construction. However, the results indicate that it would be impossible to connect the middle and eastern regions. We recommend that conservation resources and efforts should focus on population maintenance and connectivity of the western and middle regions. Future road building plans must consider the impact of their construction and barrier effect on wild camel habitat, and decision makers should expand assessment to include the entirely historical distribution range of the wild camel, not just the three current isolated habitat regions.

Morphological and genetic differentiation in isolated populations of Mexican beech Fagus grandifolia subsp. mexicana

Mexican beech [Fagus grandifolia subsp. mexicana (Martinez) A.E.Murray] is a subspecies endemic to the Sierra Madre Oriental Mountains and considered endangered due to the low density of its populations and high degree of habitat fragmentation and environmental specificity. Because its morphological and genetic variation is associated with its ability to adapt to changes in environmental conditions, the objective of this study was to determine whether phenotypic and genotypic variation exist, and it relationships with population reduction events. In four beech populations in the states of Hidalgo and Veracruz, we analyzed 11 morphological variables for leaves and 6 microsatellite markers. The morphological variables that to discriminate between populations were related to the size of the leaf, but a robust differentiation pattern was not found, given that independent groups of leaves were identified. The populations located closest to each other, had greater genetic variation and less genetic distance; populations in the extreme north and south had the lowest genetic variation. Genetic differentiation among populations was associated with reduction in population size. In the 3 localities in Hidalgo, recent bottlenecks were identified, and in Veracruz, an old bottleneck was found. Variation in leaf morphology and genetic structure of Mexican beech populations could be the result of a combination of various geographical, climate and ecological factors.

Prioritising conservation actions for biodiversity: Lessening the impact from habitat fragmentation and climate change

The interacting impacts of habitat fragmentation and climate change present a substantial threat for biodiversity, constituting a ‘deadly anthropogenic cocktail’. A range of conservation actions has been proposed to allow biodiversity to respond to those environmental changes. However, determining the relative effectiveness of these actions has been hampered by incomplete evidence. Empirical studies have provided important insights to inform conservation, but the challenge of considering multiple actions at large spatial and temporal scales is considerable. We adopt an individual-based modelling approach to qualitatively assess the effectiveness of alternative conservation actions in facilitating range expansion and patch occupancy for eight virtual species. We test actions to: (i) improve the quality of existing habitat patches, (ii) increase the permeability of the surrounding matrix, (iii) restore degraded habitat, (iv) create new habitat patches to form stepping-stones or (v) create new habitat to enlarge existing habitat patches. These actions are systematically applied to six real landscapes of the UK, which differ in their degree of habitat fragmentation and availability. Creating new habitat close to existing patches typically provides the strongest benefits for both range expansion and patch occupancy across species and landscapes. However, some landscapes may be so degraded that even under unrealistically high levels of management action, species' performances cannot be rescued. We identify that it is possible to develop a triage of conservation actions at the landscape, species and investment level, thereby providing timely evidence to inform action on the ground to lessen the hangover from the deadly anthropogenic cocktail.

Diversity of the Grass Layer of Urbanized Communities Dominated by Invasive Acer negundo

The α-diversity of the grass layer was compared for communities exposed to Acer negundo and unexposed communities. The communities were aligned by characteristics by their degrees of urbanization, fragmentation, and anthropogenic disturbance. The research was carried out in the city of Yekaterinburg (the southern taiga subzone, Russia) at 13 sites. Each site included two sampling plots: one in communities dominated by A. negundo and the other in communities dominated by other tree species (total of 26 communities). It is established that the key factors of variation in the grass layer characteristics are the dominant tree species (A. negundo or other trees) and the stand area. The number of grass species per 400 m2 was lower in A. negundo thickets than under the crowns of other trees: 17 ± 3 and 28 ± 3, respectively. However, communities with and without A. negundo did not differ in the values of the Shannon index, the degree of dominance, or the ratios of annual/perennial and graminoid/forb species. An increase in the degree of habitat fragmentation was accompanied by an increase in the proportion of synanthropic species, both under the canopy of A. negundo and in communities dominated by other trees. Methodically, the results showed that assessment of the consequences of plant invasion should always take into account the spatial patterns of determination of the structure of communities.

Fragmentation of Neanderthals' pre-extinction distribution by climate change

Neanderthals lived in Eurasia alongside anatomically modern humans (AMHs) until some 40,000 years ago. The extinction of Neanderthals is attributed to either climatic change, or to the effect of competition with AMHs. We used fossil occurrence records and paleoclimatic data to model the potential distributions of H. sapiens and H. neanderthalensis using Species Distribution Models, and calculated the degree of habitat quality and connectivity at successive time steps. We found that both species potential geographic ranges progressively retreated from their northeastern borders beginning with 44 ka. Although the degree of habitat loss is similar for the two species, the potential range for H. sapiens was constantly some 50% larger on average. The degree of habitat fragmentation, and the size, number, and average distance between optimal habitat patches was initially very similar for the two species. However, all these landscape metrics showed a progressive deterioration for H. neanderthalensis only over time. At the end of their existence, the most suitable habitat patches for Neanderthals were small and isolated, and their inferred climatic niche width was statistically narrower than in H. sapiens. This does not mean that climate worsening drove Neanderthals extinct, yet it suggests extinction risk for the latter markedly increased over time, towards its actual extinction date.

Degradation of natural habitats by roads: Comparing land-take and noise effect zone

Roads may act as barriers, negatively influencing the movement of animals, thereby causing disruption in landscapes. Roads cause habitat loss and fragmentation not only through their physical occupation, but also through traffic noise. The aim of this study is to provide a method to quantify the habitat degradation including habitat loss and fragmentation due to road traffic noise and to compare it with those of road land-take. Two types of fragmentation effects are determined: structural fragmentation (based on road land-take only), and functional fragmentation (noise effect zone fragmentation, buffer using a threshold of 40dB). Noise propagation for roads with a traffic volume of more than 1000 vehicles per day was simulated by Calculation of Road Traffic Noise (CRTN) model. Habitat loss and fragmentation through land-take and noise effect zone were calculated and compared in Zagros Mountains in western Iran. The study area is characterized by three main habitat types (oak forest, scattered woodland and temperate grassland) which host endangered and protected wildlife species. Due to topographic conditions, land cover type, and the traffic volume in the region, the noise effect zone ranged from 50 to 2000m which covers 18.3% (i.e. 516,929.95ha) of the total study area. The results showed that the habitat loss due to noise effect zone is dramatically higher than that due to road land-take only (35% versus 1.04% of the total area). Temperate grasslands lost the highest proportion of the original area by both land-take and noise effect zone, but most area was lost in scattered woodland as compared to the other two habitat types. The results showed that considering the noise effect zone for habitat fragmentation resulted in an increase of 25.8% of the area affected (316,810ha) as compared to using the land-take only (555,874ha vs. 239,064ha, respectively). The results revealed that the degree of habitat fragmentation is increasing by considering the noise effect zone. We conclude that, although the roads are breaking apart the patches by land-take, road noise not only dissects habitat patches but takes much larger proportions of or even functionally eliminates entire patches.

Geographic variation in type I dialects of Hermit Warblers: does fragmented habitat promote variation in song?

We evaluated the role of habitat fragmentation in promoting song variation and the potential for the generation of dialects within four type I dialect areas of Hermit Warblers (Setophaga occidentalis). The dialect areas differed markedly in the degree of habitat fragmentation due to topographic relief, aspect, and elevation. Geographic variation in song was greatest in the most highly fragmented area, but substantial variation existed in all dialect areas including the area with no obvious fragmentation. Songs in isolated and partially isolated portions of a dialect area differed from songs in the more continuous areas, but geographic variation was also found within the continuous portions of dialect areas. Much of the variation in song structure was clinal, crossing discontinuities in habitat. Within a dialect area, songs varied geographically with differences often apparent over distances ≤10 km in continuous habitat. Despite the great geographic variation in song, evidence that fragmented habitat promotes song variation is insufficient to explain the observed pattern of variation in type I song. Noticeable song variation over relatively small distances suggests males converge on similar type I songs locally while periodic large-scale disturbances, primarily wildfire, are likely important in the partitioning of variable dialects sufficiently in space and time for the generation of new dialects.

Spread rates on fragmented landscapes: the interacting roles of demography, dispersal and habitat availability

AbstractAimWe still lack a comprehensive understanding of the relative importance of demographic, dispersal and landscape characteristics on species’ rates of range expansion (RRE) and on how these factors interact. Here, we provide an analysis of these effects for passive dispersers, by investigating how habitat characteristics, such as habitat quality, availability and fragmentation, interplay with species’ dispersal characteristics in determining species’RRE. In addition, we assessed the predictability ofRREin cases where we have the knowledge of a species’ demography, dispersal and habitat availability.MethodsUsing the newly available individual‐based modelling platform,RangeShifterwe simulated the range expansion of species with different dispersal abilities, by varying mean dispersal distance and number of emigrants, on various landscapes. Landscapes varied in habitat quality (in terms of carrying capacity and species’ growth rates) and in habitat availability (in terms of the proportion of suitable habitat and its degree of fragmentation).ResultsOur results show that 55% of the total variation inRREwas explained by our six main effects, being considerably faster in landscapes with more suitable habitat, but only slightly affected by the degree of habitat fragmentation. Also, synergies between the amount of suitable habitat and species dispersal characteristics had significant positive effects on range expansion. Notably, however, 33% of variation inRREwas not explained by any of the tested factors or interactions between them and can be considered inherent and irreducible uncertainty.Main conclusionsSimulation‐based approaches provide important insights into the drivers ofRREthat are relevant for conservation planning. For instance, our results indicate when it is likely to be better to allocate resources to improve existing habitat rather than creating new habitat, and vice versa. Additionally, our results emphasize that there will often be substantial uncertainty in theRRE, which needs to be taken into account for ecological management.

The Relationship between Habitat Loss and Fragmentation during Urbanization: An Empirical Evaluation from 16 World Cities.

Urbanization results in habitat loss and habitat fragmentation concurrently, both influencing biodiversity and ecological processes. To evaluate these impacts, it is important to understand the relationships between habitat loss and habitat fragmentation per se (HLHF) during urbanization. The objectives of this study were two-fold: 1) to quantify the different forms of the HLHF relationship during urbanization using multiple landscape metrics, and 2) to test the validity of the HLHF relations reported in the literature. Our analysis was based on a long-term urbanization dataset (1800–2000) of 16 large cities from around the world. Habitat area was represented as the percentage of non-built-up area in the landscape, while habitat fragmentation was measured using several landscape metrics. Our results show that the relationship between habitat loss and habitat fragmentation during urbanization is commonly monotonic—linear, exponential, or logarithmic, indicating that the degree of habitat fragmentation per se increases with habitat loss in general. We compared our results with 14 hypothesized HLHF relationships based on simulated landscapes found in the literature, and found that four of them were consistent with those of urbanization, whereas the other ten were not. Also, we identified six new HLHF relationships when fragmentation was measured by total core area, normalized total core area, patch density, edge density and landscape shape index, respectively. In addition, our study demonstrated that the “space-for-time” approach, frequently used in ecology and geography, generated specious HLHF relationships, suggesting that this approach is largely inappropriate for analyses of urban landscapes that are highly heterogeneous in space and unusually contingent in dynamics. Our results show both generalities and idiosyncrasies of the HLHF relationship, providing new insights for assessing ecological effects of urbanization.

Fuzzy Logic Method for Evaluating Habitat Suitability in an Estuary Affected by Land Reclamation

This paper proposes an integrated approach to the assessment of estuarine habitat suitability based on a fuzzy logic method. Specifically, fuzzy logic is used to construct the Habitat Suitability Index (HSI) as a supplementary metric when field data is scarce. The HSI is used in turn to build the Habitat Aggregation Index (HAI) that considers the internal patches and fragmentation of the habitat. We applied the proposed tool to the Yellow River Estuary to demonstrate its implementation and efficacy. The habitat suitability of the estuary was evaluated under a host of scenarios with different terrain conditions to simulate the consequences of the long term land reclamation activities it has experienced during the past two decades. The findings indicate that from 1989 to 1999, the suitable habitat area (HSI ≥ 0.6) for jellyfish decreased by 2–6 % when flow was less than 500 m3/s, but increased 5–6.5 % when flow was greater than 800 m3/s. The suitable habitat area decreased by more than 30 % under the land reclamation that occurred from 1999 to 2009. The suitable habitat area for Chinese shrimp decreased by 9–13 % from 1989 to 1999 and 67–78 % from 1999 to 2009. Both the HAI of the habitat for jellyfish and Chinese shrimp decreased during 1989 to 1999 and then increased in 2009, indicating that the degree of habitat fragmentation that worsened under the reclamation during 1989–1999 was ameliorated during 1999–2009. This proposed approach provides a novel evaluation tool for habitat suitability in estuaries.

Linking Land‐Use Scenarios, Remote Sensing and Monitoring to Project Impact of Management Decisions

AbstractLarge‐scale modifications of natural ecosystems lead to mosaics of natural, semi‐natural and intensively used habitats. To improve communication in conservation planning, managers and other stakeholders need spatially explicit projections at the landscape scale of future biodiversity under different land‐use scenarios. For that purpose, we visualized the potential effect of five forest management scenarios on the avifauna of Kakamega Forest, western Kenya using different measures of bird diversity and GIS data. Future projections of bird diversity combined: (1) remotely sensed data on the spatial distribution of different forest management types; (2) field‐based data on the biodiversity of birds in the different management types; and (3) forest management scenarios that took into account possible views of various stakeholder groups. Management scenarios based on the species richness of forest specialists were very informative, because they reflected differences in the proportions of near‐natural forest types among the five scenarios. Projections based on community composition were even more meaningful, as they mirrored not only the proportions of near‐natural forest types, but also their perimeter to area ratios. This highlights that it is important to differentiate effects of the total area of available habitat and the degree of habitat fragmentation, both for species richness and community composition. Furthermore, our study shows that an approach that combines land‐use scenarios, remote sensing and field data on biodiversity can be used to visualize future biodiversity. As such, visualizations of alternative scenarios are valuable for successful communication about conservation planning considering different groups of stakeholders in species‐rich tropical forests.

Life history of theGlanville fritillary butterfly in fragmented versus continuous landscapes

Habitat loss and fragmentation threaten the long-term viability of innumerable species of plants and animals. At the same time, habitat fragmentation may impose strong natural selection and lead to evolution of life histories with possible consequences for demographic dynamics. The Baltic populations of the Glanville fritillary butterfly (Melitaea cinxia) inhabit regions with highly fragmented habitat (networks of small dry meadows) as well as regions with extensive continuous habitat (calcareous alvar grasslands). Here, we report the results of common garden studies on butterflies originating from two highly fragmented landscapes (FL) in Finland and Sweden and from two continuous landscapes (CL) in Sweden and Estonia, conducted in a large outdoor cage (32 by 26 m) and in the laboratory. We investigated a comprehensive set of 51 life-history traits, including measures of larval growth and development, flight performance, and adult reproductive behavior. Seventeen of the 51 traits showed a significant difference between fragmented versus CL. Most notably, the growth rate of postdiapause larvae and several measures of flight capacity, including flight metabolic rate, were higher in butterflies from fragmented than CL. Females from CL had shorter intervals between consecutive egg clutches and somewhat higher life-time egg production, but shorter longevity, than females from FL. These results are likely to reflect the constant opportunities for oviposition in females living in continuous habitats, while the more dispersive females from FL allocate more resources to dispersal capacity at the cost of egg maturation rate. This study supports theoretical predictions about small population sizes and high rate of population turnover in fragmented habitats selecting for increased rate of dispersal, but the results also indicate that many other life-history traits apart from dispersal are affected by the degree of habitat fragmentation.

Landscape Structure Shapes Habitat Finding Ability in a Butterfly

Land-use intensification and habitat fragmentation is predicted to impact on the search strategies animals use to find habitat. We compared the habitat finding ability between populations of the speckled wood butterfly (Pararge aegeria L.) from landscapes that differ in degree of habitat fragmentation. Naïve butterflies reared under standardized laboratory conditions but originating from either fragmented agricultural landscapes or more continuous forested landscapes were released in the field, at fixed distances from a target habitat patch, and their flight paths were recorded. Butterflies originating from fragmented agricultural landscapes were better able to find a woodlot habitat from a distance compared to conspecifics from continuous forested landscapes. To manipulate the access to olfactory information, a subset of individuals from both landscape types were included in an antennae removal experiment. This confirmed the longer perceptual range for butterflies from agricultural landscapes and indicated the significance of both visual and olfactory information for orientation towards habitat. Our results are consistent with selection for increased perceptual range in fragmented landscapes to reduce dispersal costs. An increased perceptual range will alter the functional connectivity and thereby the chances for population persistence for the same level of structural connectivity in a fragmented landscape.

Home Range and Ranging Behaviour of Bornean Elephant (Elephas maximus borneensis) Females

BackgroundHome range is defined as the extent and location of the area covered annually by a wild animal in its natural habitat. Studies of African and Indian elephants in landscapes of largely open habitats have indicated that the sizes of the home range are determined not only by the food supplies and seasonal changes, but also by numerous other factors including availability of water sources, habitat loss and the existence of man-made barriers. The home range size for the Bornean elephant had never been investigated before.Methodology/Principal FindingsThe first satellite tracking program to investigate the movement of wild Bornean elephants in Sabah was initiated in 2005. Five adult female elephants were immobilized and neck collars were fitted with tracking devices. The sizes of their home range and movement patterns were determined using location data gathered from a satellite tracking system and analyzed by using the Minimum Convex Polygon and Harmonic Mean methods. Home range size was estimated to be 250 to 400 km2 in a non-fragmented forest and 600 km2 in a fragmented forest. The ranging behavior was influenced by the size of the natural forest habitat and the availability of permanent water sources. The movement pattern was influenced by human disturbance and the need to move from one feeding site to another.Conclusions/SignificanceHome range and movement rate were influenced by the degree of habitat fragmentation. Once habitat was cleared or converted, the availability of food plants and water sources were reduced, forcing the elephants to travel to adjacent forest areas. Therefore movement rate in fragmented forest was higher than in the non-fragmented forest. Finally, in fragmented habitat human and elephant conflict occurrences were likely to be higher, due to increased movement bringing elephants into contact more often with humans.

Patch occupancy and abundance of local populations in landscapes differing in degree of habitat fragmentation: a case study of the colonial black‐headed gull, Chroicocephalus ridibundus

AbstractAim This study investigated whether habitat fragmentation at the landscape level influences patch occupancy and abundance of the black‐headed gull, Chroicocephalus ridibundus, and whether the response of the species to environmental factors is consistent across replicated landscape plots.Location Water bodies (habitat patches) in southern Poland.Methods Surveys were conducted in two landscape types (four plots in each): (1) more‐fragmented landscape, in which habitat patches were small (mean size 2.2–6.2 ha) and far apart (mean distance 2.5–3.1 km); and (2) less‐fragmented landscape, in which habitat patches were large (mean size 9.2–16.5 ha) and separated by short distances (mean 0.9–1.4 km). Observations were performed twice in 284 potential habitat patches during the 2007 breeding season.Results Colonies were significantly more frequent and larger in the less‐fragmented landscapes than in the more‐fragmented ones. Probability of patch occupancy and number of breeding birds were positively related with patch size and these relationships were especially strong in the more‐fragmented landscapes. In the less‐fragmented landscapes, the occurrence of black‐headed gulls was negatively related to the distance to the nearest local population, but in the more‐fragmented landscapes such a relationship was not detected. As distance to the nearest habitat patch increased, the probability of the patch occupancy decreased in the more‐fragmented landscapes. Moreover, abundance was negatively influenced by distance to the nearest habitat patch, especially strongly in more‐fragmented landscapes. Proximity of corridors (rivers) positively influenced the occupation of patches regardless of landscape type. The number of islets positively influenced occupancy and abundance of local populations, and this relationship was stronger in the more‐fragmented landscapes.Main conclusions Our results are in agreement with predictions from metapopulation theory and are the first evidence that populations of black‐headed gulls may have a metapopulation structure. However, patch occupancy and abundance were differentially affected by explanatory variables in the more‐fragmented landscapes than in the less‐fragmented ones. This implies that it is impossible to derive, a priori, predictions about presence/abundance patterns based on only a single landscape.

Seed germination tests of the parasitic perennial Viscum album (Viscaceae) from fragmented habitats at the northern edge of its range

Background and aims - Despite being a rather common species throughout Europe, little is known about the effects of habitat change on the fitness of Viscum album. We expected to find a reduction in fitness in V. album populations growing in fragmented habitats resulting from a loss of genetic diversity through increased inbreeding. Methods - We studied seed germination as a measure of fitness among sixteen Belgian V. album popula tions varying in size and degree of isolation to investigate the fitness consequences of habitat fragmenta tion. Populations were sampled from two landscapes differing in their degree of habitat fragmentation and V. album population characteristics. We also compared germination percentages of three populations at three different temperatures (5, 20, 30?C) to examine the potential effects of climate change on V. album regeneration in northern Europe. Key results - Germination percentages (at 20?C) were high (69-100%) and we found no evidence of relationships between germination and population size, density, or area. There was no direct relationship between germination percentage and population isolation within study regions, but connectivity among populations appears to be important. Samples from the more fragmented habitat showed a negative correla tion between germination percentage and the proportion of females, suggesting reduced mate availability and pollination resulting from increased isolation of populations. There was no significant difference in mean germination percentages among the three temperature treatments, bui the high temperature samples (30?C) exhibited the highest variation in germination success. Conclusion - Our results suggest that V. album has evolved high germination success to compensate for limited success in establishing on a host plant. Successful germination under a wide range of environmental conditions is expected to increase the likelihood of establishing on host plants, possibly helping V. album respond to changes in climate.