Apples, Oranges, and Probabilities: Integrating Multiple Factors into Biodiversity Conservation with Consistency

We explore the problem of integrating some of the many factors involved in conservation planning by focusing on their effects on a common currency of conservation success, the probability of persistence. This approach has the potential to reduce many of the difficulties inherent in combining different pattern and process factors. For handling information expressed as probabilities, five area-selection methods are compared.     

Dynamics of Hybridization and Introgression in Red Wolves and Coyotes

Abstract:  Hybridization and introgression are significant causes of endangerment in many taxa and are considered the greatest biological threats to the reintroduced population of red wolves ( Canis rufus ) in North Carolina (U.S.A.). Little is known, however, about these processes in red wolves and coyotes ( C. latrans ). We used individual-based simulations to examine the process of hybridization and introgression between these species. Under the range of circumstances we considered, red wolves in colonizing and established populations were quickly extirpated, persisted near the carrying capacity, or had intermediate outcomes. Sensitivity analyses suggested that the probabilities of quasi extinction and persistence of red wolves near the carrying capacity were most affected by the strength of two reproductive barriers: red wolf challenges and assortative mating between red wolves and coyotes. Because model parameters for these barriers may be difficult to estimate, we also sought to identify other predictors of red wolf population fate. The proportion of pure red wolves in the population was a strong predictor of the future probabilities of red wolf quasi extinction and persistence. Finally, we examined whether sterilization can be effective in minimizing introgression while allowing the reintroduced red wolf population to grow. Our results suggest sterilization can be an effective short-term strategy to reduce the likelihood of extirpation in colonizing populations of red wolves. Whether red wolf numbers are increased by sterilization depends on the level of sterilization effort and the acting reproductive barriers. Our results provide an outline of the conditions likely required for successful reestablishment and long-term maintenance of populations of wild red wolves in the presence of coyotes. Our modeling approach may prove generally useful in providing insight into situations involving complex species interactions when data are few.     

Landscape--wildfire interactions in southern Europe: implications for landscape management

Every year approximately half a million hectares of land are burned by wildfires in southern Europe, causing large ecological and socio-economic impacts. Climate and land use changes in the last decades have increased fire risk and danger. In this paper we review the available scientific knowledge on the relationships between landscape and wildfires in the Mediterranean region, with a focus on its application for defining landscape management guidelines and policies that could be adopted in order to promote landscapes with lower fire hazard. The main findings are that (1) socio-economic drivers have favoured land cover changes contributing to increasing fire hazard in the last decades, (2) large wildfires are becoming more frequent, (3) increased fire frequency is promoting homogeneous landscapes covered by fire-prone shrublands; (4) landscape planning to reduce fuel loads may be successful only if fire weather conditions are not extreme. The challenges to address these problems and the policy and landscape management responses that should be adopted are discussed, along with major knowledge gaps.     

Is research keeping up with changes in landscape policy? A review of the literature

Several innovative directions for landscape policy development and implementation have emerged over recent years. These include: (i) an expansion of scope to include all landscape aspects and landscape types, (ii) an increased emphasis on public participation, (iii) a focus on designing measures appropriate for different contexts and scales, and (iv) encouraging support for capacity-building. In this paper, we evaluate the extent to which these policy directions are reflected in the practice of academic landscape research. We evaluate all research papers published in three leading landscape journals over six years, as well as published research papers relating directly to the European Landscape Convention. The latter, which was adopted in 2000, establishes a framework for landscape protection, planning and management in Europe and is to date the only international legal instrument of its kind. Results indicate that whilst policy innovations do not appear to be a major stimulus for academic research, studies nevertheless address a range of landscape aspects, types and scales (albeit with a slight bias towards bio-physical landscape aspects). However, geographical representativeness of research is weak and dominated by the United States and northern/western Europe, and research capacity likewise appears to be unevenly distributed. Landscape research is also limited in the extent to which it involves stakeholders or develops innovative methods for doing so, notwithstanding that this remains a key challenge for policy-makers. Results point to the potential for landscape research to address areas (topical and geographical) which have received little attention to date, as well as suggesting mutual benefits of stronger links between policy and academia.     

A spatial exploration of informal trail networks within Great Falls Park, VA

Informal (visitor-created) trails represent a threat to the natural resources of protected natural areas around the globe. These trails can remove vegetation, displace wildlife, alter hydrology, alter habitat, spread invasive species, and fragment landscapes. This study examines informal and formal trails within Great Falls Park, VA, a sub-unit of the George Washington Memorial Parkway, managed by the U.S. National Park Service. This study sought to answer three specific questions: 1) Are the physical characteristics and topographic alignments of informal trails significantly different from formal trails, 2) Can landscape fragmentation metrics be used to summarize the relative impacts of formal and informal trail networks on a protected natural area? and 3) What can we learn from examining the spatial distribution of the informal trails within protected natural areas?     

Fragmentation drives tropical forest fragments to early successional states: A modelling study for Brazilian Atlantic forests

Land use leads to massive habitat destruction and fragmentation in tropical forests. Despite its global dimensions the effects of fragmentation on ecosystem dynamics are not well understood due to the complexity of the problem. We present a simulation analysis performed by the individual-based model FORMIND. The model was applied to the Brazilian Atlantic Forest, one of the world's biodiversity hot spots, at the Plateau of São Paulo. This study investigates the long-term effects of fragmentation processes on structure and dynamics of different sized remnant tropical forest fragments (1-100 ha) at community and plant functional type (PFT) level. We disentangle the interplay of single effects of different key fragmentation processes (edge mortality, increased mortality of large trees, local seed loss and external seed rain) using simulation experiments in a full factorial design.Our analysis reveals that particularly small forest fragments below 25 ha suffer substantial structural changes, biomass and biodiversity loss in the long term. At community level biomass is reduced up to 60%. Two thirds of the mid- and late-successional species groups, especially shade-tolerant (late successional climax) species groups are prone of extinction in small fragments. The shade-tolerant species groups were most strongly affected; its tree number was reduced more than 60% mainly by increased edge mortality. This process proved to be the most powerful of those investigated, explaining alone more than 80% of the changes observed for this group. External seed rain was able to compensate approximately 30% of the observed fragmentation effects for shade-tolerant species.Our results suggest that tropical forest fragments will suffer strong structural changes in the long term, leading to tree species impoverishment. They may reach a new equilibrium with a substantially reduced subset of the initial species pool, and are driven towards an earlier successional state. The natural regeneration potential of a landscape scattered with forest fragments appears to be limited, as external seed rain is not able to fully compensate for the observed fragmentation-induced changes. Our findings suggest basic recommendations for the management of fragmented tropical forest landscapes.     

Effects of density-dependent dispersal behaviours on the speed and spatial patterns of range expansion in predator-prey metapopulations

Dispersal can strongly affect the spatiotemporal dynamics of a species (its spread, spatial distribution and persistence). We investigated how two dispersal behaviours, namely prey evasion (PE) and predator pursuit (PP), affect the dynamics of a predator-prey system. PE portrays the tendency of prey avoiding predators by dispersing into adjacent patches with fewer predators, while PP describes the tendency of predators to pursue the prey by moving into patches with more prey. Based on the Beddington predation model, a spatially explicit metapopulation model was built to incorporate PE and PP. Numerical simulations were run to investigate the effects of PE and PP on the rate of spread, spatial synchrony and the persistence of populations. Results show that both PE and PP can alter spatial synchrony although PP has a weaker desynchronising effect than PE. The predator-prey system without PE and PP expanded in circular waves. The effect of PE can push the prey to distribute in a circular ring front, whereas the effect of PP can change the circular waves to anisotropic expansion. Furthermore, weak PE and PP can accelerate the spread of prey while strong and disproportionate intensities slow down the range expansion. The effects of PE and PP further enhance the population size, break down the spatial synchrony and promote the persistence of populations.     

A landscape approach to quantifying land cover changes in Yulin, Northwest China

In this study we quantified land cover changes in the arid region of Yulin City, Northwest China between 1985 and 2000 using remote sensing and GIS in conjunction with landscape modeling. Land covers were mapped into 20 categories from multitemporal Landsat TM images. Five landscape indices were calculated from these maps at the land cover patches level. It was found that fallow land decreased by 125,148 ha while grassland and woodland increased by 107,975 and 17,157 ha, respectively. Landscape heterogeneity, dominance and fractal dimension changed little during the 15-year period while landscape became more fragmented, with an index rising from 0.56 to 0.58. The major factors responsible for these changes are identified as the change in the government policy on preserving the environment, continued growth in mining, and urbanization.     

淮北中湖采煤沉陷区治理前后景观格局变化研究

基于淮北中湖采煤沉陷区2005年、2014年和2018年的遥感影像进行地表景观解译,研究治理前后该区景观格局变化特征及生态效应.结果表明:治理前,该区耕地破碎化加剧、景观优势最大并持续减弱,沉陷积水区水体呈聚集化趋势;治理后,景观基质由耕地变为水体,林地、草地面积显著增加且景观优势上升,人工湖泊水体聚集程度高.区域景观...     

武汉市耕地景观游憩功能与可达性的空间匹配格局

揭示耕地景观游憩功能的供给能力与其可达性的空间匹配格局,可以为耕地景观游憩功能的合理布局、开发与利用提供依据。以武汉市为例,采用指标评价法和专家打分法,结合GIS空间分析,建立了耕地景观游憩功能的空间格局研究框架,对耕地景观游憩功能的供应潜力、可达性、及两者空间匹配等方面开展了研究。结果表明:(1)武汉市耕地景观游憩功能供应潜力的空间分布呈现从中心城区边缘向外逐渐降低的格局;(2)武汉市耕地景观游憩功能可达性呈现"中西部高,边缘低"的分布格局;(3)根据耕地景观游憩功能的供应潜力与可达性的空间匹配关系,将武汉市耕地景观游憩服务分为四类:高供应-高可达,高供应-低可达,低供应-高可达,低供应-低可达;这四类面积分别占研究区域的26.17%、25.24%、17.33%、31.26%。对耕地景观游憩功能的合理开发与利用、促进耕地利用的多功能化具有重要的现实意义。