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1.
Diego A. Zárrate-Charry Aimee L. Massey José F. González-Maya Matthew G. Betts 《Biodiversity and Conservation》2018,27(13):3373-3392
Human–wildlife conflict, habitat loss, and prey hunting are the main threats to carnivore species worldwide. Forest conversion as consequence of deforestation and agricultural expansion increases the proximity between carnivores and humans, thereby escalating conflicts. Knowledge about carnivore species in data-poor countries, such as Colombia, is scarce which has the potential to result in poor landscape planning decisions. For many species, the only existing spatial information resides in expert-driven approaches which result in coarse-resolution ‘extent-of-occurrence’ maps. There is an increasing need for the development of methodologies to identify conservation and management areas at appropriate scales. Multi-criteria approaches will allow the inclusion of diverse species attributes enabling environmental institutions to address complex landscape decisions that result in conservation and management of carnivore habitat. We present a multi-criteria spatial identification tool for conservation and management areas, focused on Jaguars (Panthera onca) in the Sierra Nevada de Santa Marta, in northern Colombia. Our approach identifies areas based on the relationship between three spatial criteria: (1) suitable habitat patches, (2) habitat connectivity, and (3) zones of higher likelihood of human–jaguar conflict. We identified areas with the presence of at least one spatial criteria in 32% of the study area. Only 16.28% of these occur within protected areas (PAs) and the remaining fall on private lands (83.72%), either within (35.68%) or outside (48.04%) buffer zones of PAs. Our results highlight the need for multi-stakeholder collaborative approaches given that most proposed conservation areas fall on private rather than public lands. 相似文献
2.
Anthropogenic landscape alteration is rather common in many protected areas (PAs), jeopardizing the efficacy of PAs conservation. However, the general consensus is that PAs still remain effective in habitat conservation. To assess the efficacy of landscape-level conservation, we examined landscape alterations in the Changbai Mountain Biosphere Reserve (CMBR), which was established in 1960 as a “flagship” protected area in China. Based on analyses of high-resolution satellite images and data of forest inventory, field survey and interview, we developed two new indexes to assess the efficacy of landscape conservation, i.e. the quality index of protected landscape and the interference index of anthropogenic landscape. From 1993 to 2012, the quality index increased from 74.48 to 75.50, and the interference index decreased from 0.49 to 0.06, suggesting that the overall quality of protected landscape improved and the degree of anthropogenic interference decreased in CMBR. The increase in landscape quality was mainly due to the progressive vegetation recovery of previous cutover land in the windthrow area, the cease of the use of the cultivated land, and the amelioration of spatial pattern of protected landscape. We conclude that the current landscape conservation methods used in CMBR are effective, and the method we developed has the potential to be used to assess the efficacy of landscape-level conservation in nature reserves worldwide. 相似文献
3.
Bilal Habib Pallavi Ghaskadbi Shaheer Khan Zehidul Hussain Parag Nigam 《Ecology and evolution》2021,11(4):1653
Large carnivores play an important role in the functioning of ecosystems, yet their conservation remains a massive challenge across the world. Owing to wide‐ranging habits, they encounter various anthropogenic pressures, affecting their movement in different landscape. Therefore, studying how large carnivores adapt their movement to dynamic landscape conditions is vital for management and conservation policy.A total of 26 individuals across 4 species of large carnivores of different sex and age classes (14 Panthera tigris, 3 Panthera pardus, 5 Cuon alpinus, and 4 Canis lupus pallipes) were GPS collared and monitored from 2014–19. We quantified movement parameters (step length and net squared displacement) of four large carnivores in and outside protected areas in India. We tested the effects of human pressures such as human density, road network, and landuse types on the movement of the species. We also examined the configuration of core areas as a strategy to subsist in a human‐dominated landscape using BBMM.Mean displacement of large carnivores varied from 99.35 m/hr for leopards to 637.7 m/hr for wolves. Tigers outside PAs exhibited higher displacement than tigers inside PAs. Moreover, displacement during day–night was significantly different for tigers inside and outside PAs. Similarly, wolf also showed significant difference between day‐night movement. However, no difference in day–night movement was found for leopard and dholes. Anthropogenic factors such as road length and proportion of agriculture within the home range of tigers outside PAs were found to be significantly different. All the habitat variables in the home range showed significant difference between the social canids. The core area size for tiger outside PA and wolf was found greater than PAs.The study on movement of large carnivore species across landscapes is crucial for conservation planning. Our findings can be a starting point for interlinking animal movement and landscape management of large carnivore conservation in the current Anthropocene. 相似文献
4.
Local and landscape factors determining occurrence of phyllostomid bats in tropical secondary forests 总被引:1,自引:0,他引:1
Avila-Cabadilla LD Sanchez-Azofeifa GA Stoner KE Alvarez-Añorve MY Quesada M Portillo-Quintero CA 《PloS one》2012,7(4):e35228
Neotropical forests are being increasingly replaced by a mosaic of patches of different successional stages, agricultural fields and pasture lands. Consequently, the identification of factors shaping the performance of taxa in anthropogenic landscapes is gaining importance, especially for taxa playing critical roles in ecosystem functioning. As phyllostomid bats provide important ecological services through seed dispersal, pollination and control of animal populations, in this study we assessed the relationships between phyllostomid occurrence and the variation in local and landscape level habitat attributes caused by disturbance. We mist-netted phyllostomids in 12 sites representing 4 successional stages of a tropical dry forest (initial, early, intermediate and late). We also quantitatively characterized the habitat attributes at the local (vegetation structure complexity) and the landscape level (forest cover, area and diversity of patches). Two focal scales were considered for landscape characterization: 500 and 1000 m. During 142 sampling nights, we captured 606 individuals representing 15 species and 4 broad guilds. Variation in phyllostomid assemblages, ensembles and populations was associated with variation in local and landscape habitat attributes, and this association was scale-dependent. Specifically, we found a marked guild-specific response, where the abundance of nectarivores tended to be negatively associated with the mean area of dry forest patches, while the abundance of frugivores was positively associated with the percentage of riparian forest. These results are explained by the prevalence of chiropterophilic species in the dry forest and of chiropterochorous species in the riparian forest. Our results indicate that different vegetation classes, as well as a multi-spatial scale approach must be considered for evaluating bat response to variation in landscape attributes. Moreover, for the long-term conservation of phyllostomids in anthropogenic landscapes, we must realize that the management of the habitat at the landscape level is as important as the conservation of particular forest fragments. 相似文献
5.
6.
Tobias Fremout Evert Thomas Hannes Gaisberger Koenraad Van Meerbeek Jannes Muenchow Siebe Briers Claudia E. Gutierrez‐Miranda Jos L. Marcelo‐Pea Roeland Kindt Rachel Atkinson Omar Cabrera Carlos I. Espinosa Zhofre Aguirre‐Mendoza Bart Muys 《Global Change Biology》2020,26(6):3552-3568
Understanding the vulnerability of tree species to anthropogenic threats is important for the efficient planning of restoration and conservation efforts. We quantified and compared the effects of future climate change and four current threats (fire, habitat conversion, overgrazing and overexploitation) on the 50 most common tree species of the tropical dry forests of northwestern Peru and southern Ecuador. We used an ensemble modelling approach to predict species distribution ranges, employed freely accessible spatial datasets to map threat exposures, and developed a trait‐based scoring approach to estimate species‐specific sensitivities, using differentiated trait weights in accordance with their expected importance in determining species sensitivities to specific threats. Species‐specific vulnerability maps were constructed from the product of the exposure maps and the sensitivity estimates. We found that all 50 species face considerable threats, with an average of 46% of species’ distribution ranges displaying high or very high vulnerability to at least one of the five threats. Our results suggest that current levels of habitat conversion, overexploitation and overgrazing pose larger threats to most of the studied species than climate change. We present a spatially explicit planning strategy for species‐specific restoration and conservation actions, proposing management interventions to focus on (a) in situ conservation of tree populations and seed collection for tree planting activities in areas with low vulnerability to climate change and current threats; (b) ex situ conservation or translocation of populations in areas with high climate change vulnerability; and (c) active planting or assisted regeneration in areas under high current threat vulnerability but low climate change vulnerability, provided that interventions are in place to lower threat pressure. We provide an online, user‐friendly tool to visualize both the vulnerability maps and the maps indicating priority restoration and conservation actions. 相似文献
7.
1980—2015年秦岭地区景观格局变化及其对人为干扰的响应 总被引:1,自引:0,他引:1
了解景观格局变化及其对人为干扰的响应对于生态系统保护和管理具有重要意义.本研究利用秦岭地区1980—2015年土地利用数据,基于景观格局指数和地表覆盖分类系统,构建景观格局脆弱度指数和人为干扰度,研究了秦岭地区景观格局时空变化及其对人为干扰的响应.结果表明: 1980—2015年,秦岭地区景观破碎化程度逐渐增加,景观形状变得复杂,景观聚集度、连通性降低,景观格局指数空间分布呈现明显的地形分异特征;景观格局脆弱性整体呈下降趋势,其中,低脆弱区空间格局变化比较明显,主要以西安市、汉中市为中心向周围区域扩张;景观格局人为干扰程度逐渐增加,空间分布表现为东部高、西部低,北坡高、南坡低,周边高、中间低;人为干扰度越大,景观格局脆弱度、斑块密度、Shannon多样性指数越大,聚集指数、最大斑块指数越小;人为干扰程度对景观格局脆弱度影响逐渐减弱,对Shannon多样性指数、最大斑块指数的影响逐渐增强,而对斑块密度、聚集指数的影响变化不明显. 相似文献
8.
Applying a framework for landscape planning under climate change for the conservation of biodiversity in the Finnish boreal forest
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Adriano Mazziotta Maria Triviño Olli‐Pekka Tikkanen Jari Kouki Harri Strandman Mikko Mönkkönen 《Global Change Biology》2015,21(2):637-651
Conservation strategies are often established without consideration of the impact of climate change. However, this impact is expected to threaten species and ecosystem persistence and to have dramatic effects towards the end of the 21st century. Landscape suitability for species under climate change is determined by several interacting factors including dispersal and human land use. Designing effective conservation strategies at regional scales to improve landscape suitability requires measuring the vulnerabilities of specific regions to climate change and determining their conservation capacities. Although methods for defining vulnerability categories are available, methods for doing this in a systematic, cost‐effective way have not been identified. Here, we use an ecosystem model to define the potential resilience of the Finnish forest landscape by relating its current conservation capacity to its vulnerability to climate change. In applying this framework, we take into account the responses to climate change of a broad range of red‐listed species with different niche requirements. This framework allowed us to identify four categories in which representation in the landscape varies among three IPCC emission scenarios (B1, low; A1B, intermediate; A2, high emissions): (i) susceptible (B1 = 24.7%, A1B = 26.4%, A2 = 26.2%), the most intact forest landscapes vulnerable to climate change, requiring management for heterogeneity and resilience; (ii) resilient (B1 = 2.2%, A1B = 0.5%, A2 = 0.6%), intact areas with low vulnerability that represent potential climate refugia and require conservation capacity maintenance; (iii) resistant (B1 = 6.7%, A1B = 0.8%, A2 = 1.1%), landscapes with low current conservation capacity and low vulnerability that are suitable for restoration projects; (iv) sensitive (B1 = 66.4%, A1B = 72.3%, A2 = 72.0%), low conservation capacity landscapes that are vulnerable and for which alternative conservation measures are required depending on the intensity of climate change. Our results indicate that the Finnish landscape is likely to be dominated by a very high proportion of sensitive and susceptible forest patches, thereby increasing uncertainty for landscape managers in the choice of conservation strategies. 相似文献
9.
Martin Wegmann Luca Santini Benjamin Leutner Kamran Safi Duccio Rocchini Mirjana Bevanda Hooman Latifi Stefan Dech Carlo Rondinini 《Philosophical transactions of the Royal Society of London. Series B, Biological sciences》2014,369(1643)
The African protected area (PA) network has the potential to act as a set of functionally interconnected patches that conserve meta-populations of mammal species, but individual PAs are vulnerable to habitat change which may disrupt connectivity and increase extinction risk. Individual PAs have different roles in maintaining connectivity, depending on their size and location. We measured their contribution to network connectivity (irreplaceability) for carnivores and ungulates and combined it with a measure of vulnerability based on a 30-year trend in remotely sensed vegetation cover (Normalized Difference Vegetation Index). Highly irreplaceable PAs occurred mainly in southern and eastern Africa. Vegetation cover change was generally faster outside than inside PAs and particularly so in southern Africa. The extent of change increased with the distance from PAs. About 5% of highly irreplaceable PAs experienced a faster vegetation cover loss than their surroundings, thus requiring particular conservation attention. Our analysis identified PAs at risk whose isolation would disrupt the connectivity of the PA network for large mammals. This is an example of how ecological spatial modelling can be combined with large-scale remote sensing data to investigate how land cover change may affect ecological processes and species conservation. 相似文献
10.
Clarita Rodríguez‐Soto Octavio Monroy‐Vilchis Luigi Maiorano Luigi Boitani Juan Carlos Faller Miguel Á. Briones Rodrigo Núñez Octavio Rosas‐Rosas Gerardo Ceballos Alessandra Falcucci 《Diversity & distributions》2011,17(2):350-361
Aim The jaguar, Panthera onca, is a species of global conservation concern. In Mexico, the northernmost part of its distribution range, its conservation status, is particularly critical, while its potential and actual distribution is poorly known. We propose an ensemble model (EM) of the potential distribution for the jaguar in Mexico and identify the priority areas for conservation. Location Mexico. Methods We generated our EM based on three presence‐only methods (Ecological Niche Factor Analysis, Mahalanobis distance, Maxent) and considering environmental, biological and anthropogenic factors. We used this model to evaluate the efficacy of the existing Mexican protected areas (PAs), to evaluate the adequacy of the jaguar conservation units (JCUs) and to propose new areas that should be considered for conservation and management of the species in Mexico. Results Our results outline that 16% of Mexico (c. 312,000 km2) can be considered as suitable for the presence of the jaguar. Furthermore, 13% of the suitable areas are included in existing PAs and 14% are included in JCUs ( Sanderson et al., 2002 ). Main conclusions Clearly much more should be carried out to establish a proactive conservation strategy. Based on our results, we propose here new jaguar conservation and management areas that are important for a nationwide conservation blueprint. 相似文献
11.
为了探讨在热带天然林景观中不同因素对木本植物(限于乔木和灌木)功能型分布的影响,在对海南岛霸王岭的热带天然林进行样方调查的基础上,运用数量分类方法对热带天然林的木本植物进行了功能型划分,并运用冗余度分析(Redundancy analysis, RDA)分别探讨了功能型出现与否、功能型物种丰富度和功能型木本植物多度3个矩阵与环境、空间和干扰因素之间的关系。运用偏冗余度分析对影响功能型分布变化的环境、干扰、空间及其交互作用等因素进行了定量分解。结果表明:利用木材密度和潜在最大高度两个指标划分出的9个功能型,能较好的区分功能型间对生境的适应响应差异;因子分解表明,纯环境、纯人为干扰和混合的环境-人为干扰是影响3个功能型矩阵分布变化的主要因素,纯空间和与空间位置相耦合的因素相对较低;在诸多因子中,干扰类型、地形因子、土壤类型、砂砾含量、土层厚度以及经纬度坐标是影响功能型分布变化的主导因子;RDA排序分析表明,一般来讲,硬木功能型多在生境条件好和远离人为干扰的立地高发生。软木功能型则更多地出现于生境条件恶劣和人为干扰频繁的立地。而中等硬度功能型则生态幅度较宽。但除了软木灌木功能型外,其它功能型物种丰富度和木本植物多度多在土层深厚和生境条件较好的立地较高。 相似文献
12.
Using historical woodland creation to construct a long‐term,large‐scale natural experiment: the WrEN project
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Kevin Watts Elisa Fuentes‐Montemayor Nicholas A. Macgregor Victor Peredo‐Alvarez Mark Ferryman Chloe Bellamy Nigel Brown Kirsty J. Park 《Ecology and evolution》2016,6(9):3012-3025
Natural experiments have been proposed as a way of complementing manipulative experiments to improve ecological understanding and guide management. There is a pressing need for evidence from such studies to inform a shift to landscape‐scale conservation, including the design of ecological networks. Although this shift has been widely embraced by conservation communities worldwide, the empirical evidence is limited and equivocal, and may be limiting effective conservation. We present principles for well‐designed natural experiments to inform landscape‐scale conservation and outline how they are being applied in the WrEN project, which is studying the effects of 160 years of woodland creation on biodiversity in UK landscapes. We describe the study areas and outline the systematic process used to select suitable historical woodland creation sites based on key site‐ and landscape‐scale variables – including size, age, and proximity to other woodland. We present the results of an analysis to explore variation in these variables across sites to test their suitability as a basis for a natural experiment. Our results confirm that this landscape satisfies the principles we have identified and provides an ideal study system for a long‐term, large‐scale natural experiment to explore how woodland biodiversity is affected by different site and landscape attributes. The WrEN sites are now being surveyed for a wide selection of species that are likely to respond differently to site‐ and landscape‐scale attributes and at different spatial and temporal scales. The results from WrEN will help develop detailed recommendations to guide landscape‐scale conservation, including the design of ecological networks. We also believe that the approach presented demonstrates the wider utility of well‐designed natural experiments to improve our understanding of ecological systems and inform policy and practice. 相似文献
13.
EU member states have set an ambitious goal of establishing additional protected areas (PAs) preserving 30 % of terrestrial land by 2030, specifying that additions should be of high ecological quality. A targeted selection of existing PA expansions into surroundings marginally fragmented by human infrastructure, may be an efficacious strategy to secure high ecological quality by maximizing PA area, accommodating species movement, and boosting climate change resilience. We used high-resolution data on effective mesh density, a metric measuring landscape fragmentation, in the vicinity of Natura 2000 PAs (N2k) to assess their potential for expansion. Our results show that contrary to most of Central Europe, mountainous and remote territories exhibit the lowest degree of fragmentation in N2k surroundings. Fragmentation in N2k surroundings is highly correlated with national population density, while economic wealth, measured by GDP per capita, plays a minor role. To address the long-standing dilemma of where scarce economic resources in nature conservation do the most-good, we conducted a country-level comparison between fragmentation in N2k surroundings and national expenditures on nature conservation relative to N2k area. Our results show a vast incongruity in resource availability for nature conservation among EU countries. Eastern European states, especially Romania, host underfunded N2k PAs while holding the highest potential for expanding N2k PAs into low fragmented lands. If protecting low fragmented lands is accepted as an efficacious strategy to meet EU biodiversity targets our results could be used to formulate pragmatic conservation decisions, while also ensuring high ecological quality of PA additions under climate change. 相似文献
14.
Evaluating the cumulative effects of the human footprint on landscape connectivity is crucial for implementing policies for the appropriate management and conservation of landscapes. We present an adjusted multidimensional spatial human footprint index (SHFI) to analyze the effects of landscape transformation on the remnant habitat connectivity for 40 terrestrial mammal species representative of the Trans-Mexican Volcanic System in Michoacán (TMVSMich), in western central Mexico. We adjusted the SHFI by adding fragmentation and habitat loss to its original three components: land use intensity, time of human landscape intervention, and biophysical vulnerability. The adjusted SHFI was applied to four scenarios: one grouping all species and three grouping several species by habitat spatial requirements. Using the SHFI as a dispersal resistance surface and applying a circuit theory based approach, we analyzed the effects of cumulative human impact on habitat connectivity in the different scenarios. For evaluating the relationship between habitat loss and connectivity, we applied graph theory-based equivalent connected area (ECA) index. Results show over 60% of the TMVSMich has high SHFI values, considerably lowering current flow for all species. Nevertheless, the effect on connectivity of human impact is higher for species with limited dispersal capacity (100–500 m). Our approach provides a new form of evaluating human impact on habitat connectivity that can be applied to different scales and landscapes. Furthermore, the approach is useful for guiding discussions and implementing future biodiversity conservation initiatives that promote landscape connectivity as an adaptive strategy for climate change. 相似文献
15.
Valentina Oberosler Simone Tenan Elise F. Zipkin Francesco Rovero 《Ecology and evolution》2020,10(9):3881-3894
Protected areas (PAs) in the tropics are vulnerable to human encroachment, and, despite formal protection, they do not fully mitigate anthropogenic threats to habitats and biodiversity. However, attempts to quantify the effectiveness of PAs and to understand the status and changes of wildlife populations in relation to protection efficiency remain limited. Here, we used camera‐trapping data collected over 8 consecutive years (2009–2016) to investigate the yearly occurrences of medium‐to‐large mammals within the Udzungwa Mountains National Park (Tanzania), an area of outstanding importance for biological endemism and conservation. Specifically, we evaluated the effects of habitat and proxies of human disturbance, namely illegal hunting with snares and firewood collection (a practice that was banned in 2011 in the park), on species' occurrence probabilities. Our results showed variability in species' responses to disturbance: The only species that showed a negative effect of the number of snares found on occurrence probability was the Harvey's duiker, a relatively widespread forest antelope. Similarly, we found a moderate positive effect of the firewood collection ban on only the suni, another common antelope, and a negative effect on a large opportunistic rodent, the giant‐pouched rat. Importantly, we found evidence of temporal stability in occurrence probability for all species over the 8‐year study period. Our findings suggest that well‐managed PAs can sustain mammal populations in tropical forests. However, variability among species in their responses to anthropogenic disturbance necessitates consideration in the design of conservation action plans for multiple taxa. 相似文献
16.
Gabriela Cabral Rezende Thadeu Sobral-Souza Laurence Culot 《American journal of primatology》2020,82(12):e23202
Species distributions are influenced by both climate conditions and landscape structure. Here we propose an integrated analysis of climatic and landscape niche-based models for a forest-dependent primate, the endangered black lion tamarin (Leontopithecus chrysopygus). We applied both climate and landscape variables to predict the distribution of this tamarin and used this information to prioritize strategic areas more accurately. We anticipated that this approach would be beneficial for the selection of pertinent conservation strategies for this flagship species. First, we built climate and landscape niche-based models separately, combining seven algorithms, to infer processes acting on the species distribution at different scales. Subsequently, we combined climate and landscape models using the EcoLand Analysis. Our results suggest that historic and current landscape fragmentation and modification had profoundly adverse effects on the distribution of the black lion tamarins. The models indicated just 2096 km2 (out of an original distribution of 92,239 km2) of suitable areas for both climate and landscape. Of this suitable area, the species is currently present in less than 40%, which represents less than 1% of its original distribution. Based on the combined map, we determined the western and southeast regions of the species range to be priority areas for its conservation. We identified areas with high climatic and high landscape suitability, which overlap with the remaining forest fragments in both regions, for habitat conservation and population management. We suggest that areas with high climatic but low landscape suitability should be prioritized for habitat management and restoration. Areas with high landscape suitability and low climatic suitability, such as the Paranapiacaba mountain range should be considered in light of projected climate change scenarios. Our case study illustrates that a combined approach of climatic and landscape niche-based modeling can be useful for establishing focused conservation measures that may increase the likelihood of success. 相似文献
17.
With many species predicted to respond to a changing climate by shifting their distribution to climatically suitable areas, the effectiveness of static protected areas (PAs) is in question. The Madagascan PA network area has quadrupled over the past 15 years, and, although conservation planning techniques were employed to prioritise suitable areas for protection during this process, climate change impacts were not considered. We make use of species distribution models for 750 Madagascan vertebrate species to assess the potential impacts of climate change on (1) species richness across Madagascar, (2) species gain, loss and turnover in Madagascar's PAs and (3) PA network representativeness. Results indicate that Madagascar is predicted to experience substantial shifts in species richness, with most PAs predicted to experience high rates of species turnover. Provided there are no barriers to species movements, the representativeness of the current PA network will remain high for the species that are predicted to survive changes in climate by 2070, suggesting that little benefit will be gained from establishing new PAs. However, this rests on the assumption of mobility through areas currently characterised by fragmentation and anthropogenic activity, something that will require considerable expansion in conservation efforts in order to achieve. 相似文献
18.
Alison Shapcott Heather James Laura Simmons Yoko Shimizu Lauren Gardiner David Rabehevitra Rokiman Letsara Stuart Cable John Dransfield William J. Baker Mijoro Rakotoarinivo 《Ecology and evolution》2020,10(6):3120-3137
Madagascar is home to 208 indigenous palm species, almost all of them endemic and >80% of which are endangered. We undertook complete population census and sampling for genetic analysis of a relatively recently discovered giant fan palm, the Critically Endangered Tahina spectablis in 2008 and 2016. Our 2016 study included newly discovered populations and added to our genetic study. We incorporated these new populations into species distribution niche model (SDM) and projected these onto maps of the region. We developed population matrix models based on observed demographic data to model population change and predict the species vulnerability to extinction by undertaking population viability analysis (PVA). We investigated the potential conservation value of reintroduced planted populations within the species potential suitable habitat. We found that the population studied in 2008 had grown in size due to seedling regeneration but had declined in the number of reproductively mature plants, and we were able to estimate that the species reproduces and dies after approximately 70 years. Our models suggest that if the habitat where it resides continues to be protected the species is unlikely to go extinct due to inherent population decline and that it will likely experience significant population growth after approximately 80 years due to the reproductive and life cycle attributes of the species. The newly discovered populations contain more genetic diversity than the first discovered southern population which is genetically depauperate. The species appears to demonstrate a pattern of dispersal leading to isolated founder plants which may eventually lead to population development depending on local establishment opportunities. The conservation efforts currently put in place including the reintroduction of plants within the species potential suitable habitat if maintained are thought likely to enable the species to sustain itself but it remains vulnerable to anthropogenic impacts. 相似文献
19.
Alejandro Velázquez Francisco J. Romero Héctor Rangel-Cordero Gerrit W. Heil 《Biodiversity and Conservation》2001,10(7):1059-1075
Rapid habitat transformation calls for efficient methods to lead conservation efforts. For this reason, landscape analysis is becoming a major issue in biodiversity conservation. In Mexico, as in many parts of the world, management strategies are scarce so that biodiversity depletion processes continue. This is the case on the Izta-Popo volcanoes, which harbour over 10% of the total Mexican mammalian species within ca. 0.02% of the surface of Mexico. The present paper aims at assessing the effect of landscape dynamics on mammalian assemblages through a RS/GIS modelling approach. A database including all mammalian species recorded in the region from 1839 up to 1997 was compiled. The records, at genus level, were linked to land cover classes obtained from TM Landsat satellite images taken in 1986 and 1997. Land cover and habitat changes were analysed through a statistical analysis by crossing land cover maps of 1986 and 1997 which were transformed into habitat richness types. Major changes from high to medium and medium to low habitat richness classes prevail in the area. This reduces the resilience of the natural landscapes and increases the threats for most mammalian species. From a landscape ecological perspective, the present paper demonstrates the importance of the area as a unique mosaic of mammalian assemblages. 相似文献
20.
Functional ecosystems depend on biotic and abiotic connections among different environmental realms, including terrestrial, freshwater, and marine habitats. Accounting for such connections is increasingly recognized as critical for conservation of ecosystems, especially given growing understanding of the way in which anthropogenic landscape disturbances can degrade both freshwater and marine habitats. This need may be paramount in conservation planning for tropical island ecosystems, as habitats across realms are often in close proximity, and because endemic organisms utilize multiple habitats to complete life histories. In this study, we used Marxan analysis to develop conservation planning scenarios across the five largest islands of Hawaii, in one instance accounting for and in another excluding habitat connectivity between inland and coastal habitats. Native vegetation, perennial streams, and areas of biological significance along the coast were used as conservation targets in analysis. Cost, or the amount of effort required for conservation, was estimated using an index that integrated degree and intensity of anthropogenic landscape disturbances. Our results showed that when connectivity is accounted for among terrestrial, freshwater, and marine habitats, areas identified as having high conservation value are substantially different compared to results when connectivity across realms is not considered. We also showed that the trade-off of planning conservation across realms was minimal and that cross-realm planning had the unexpected benefit of selecting areas with less habitat degradation, suggesting less effort for conservation. Our cross-realm planning approach considers biophysical interactions and complexity within and across ecosystems, as well as anthropogenic factors that may influence habitats outside of their physical boundaries, and we recommend implementing similar approaches to achieve integrated conservation efforts. 相似文献