The scaling of geographic ranges: implications for species distribution models

Context

The geographic ranges of many species are responding to ongoing environmental change. Processes operating at different levels of biological organization, with corresponding spatial extents and grains and temporal rates, interact with the evolving configuration of environmental conditions to determine range dynamics.

Objectives

To synthesize understanding of scales and scaling, including relevant biological levels of organization, focusing on the processes that mediate species-environment relationships and the models used to make inferences about species distributions.

Methods

We review concepts related to the scaling of geographic ranges and implications for the most commonly used analytic methods, using simple simulations to illustrate important issues.

Results

Many processes lead to species distributions being dependent on environmental conditions within sites and within a neighborhood. Studies with large extents and fine grains can cut across several levels of biological organization (individual, within-population, and metapopulation processes) complicating interpretation. Many geographic ranges are not in dynamic equilibrium, but common models used for inference assume equilibrium. Interspecific interactions shape species distributions at multiple scales, and arguments for ignoring species interactions also assume equilibrium.

Conclusions

There is a need for timely science to inform policy and management decisions; however, we must also strive to provide predictions that best reflect our understanding of ecological systems. Species distributions evolve through time and reflect responses to environmental conditions that are mediated through individual and population processes. Species distribution models that reflect this understanding, and explicitly model dynamics, are likely to give more accurate predictions.

     

Trees and vegetation for residential energy conservation: A critical review for evidence-based urban greening in North America

The effects of trees on residential energy demand have been extensively studied over the past several decades; yet a comprehensive analysis of their magnitude, variation and emerging issues and evidence has not been updated in the literature. Given this gap, a systematic review was conducted by assessing major disciplines, geographic distributions, methods and reported energy-saving performances for cooling and heating residential homes. An overwhelming majority of literature focused on single family housing types in North America, with a strong geographic concentration in California. In North America, 40 peer-reviewed studies were published from 1979 to 2017 by 19 different journals across disciplines. Researchers used simulation modeling and empirical approaches in roughly equal proportions. The review confirms that the conceptual and empirical evidence to support trees’ energy saving effects is solid, especially for cooling effects, but the magnitude of reported energy-savings widely varied depending on climate, method, data and assumptions for buildings and trees. A building with trees used 2.3% to 90% less cooling energy, mostly through shading effects, and 1% to 20% less heating energy through windbreak effects, in comparison to buildings without trees. Takeaways for evidence-based urban greening are that practitioners and researchers should: i) pay careful attention to different methods and assumptions used when interpreting and comparing research findings ii) pursue long-term monitoring and evidence-based management to enhance tree survival and growth; iii) incorporate emerging trade-offs and synergies such as rooftop solar energy, water conservation, and net carbon savings into design and policies; and iv) prioritize planting for underserved and vulnerable communities.     

Simulating spatial complexity in dry conifer forest restoration: implications for conservation prioritization and scenario evaluation

Landscape Ecology - Several initiatives seek to increase the pace and scale of dry forest restoration and fuels reduction to enhance forest resilience to wildfire and other stressors while...     

北美海棠新品种的引进与栽培表现

海棠（Malus spp．）是重要的园林绿化植物,北美海棠因其品种多、适应性广、观赏性强等特点在我国园林景观中极有发展潜力。文章对引进的7个北美海棠品种在宁波地区的物候期、观赏性以及适应性进行观察,筛选出适合宁波地区栽植的北美海棠新品种。     

北美洲的蓝莓生产与利用

在北美洲，生产蓝莓的有美国36个州，加拿大6个省。1982—1992年北美洲种植蓝莓的总面积从62260hm^2增加到74380hm^2，栽培品种增长47.4％，野生种增长10.75％。1992—2000年总的增长率为14％，面积增加到84490hm^2。目前，北美洲蓝莓的主要品种有蓝丰、泽西、公爵、梯芙蓝、尖蓝等。美国未来较有发展前途的蓝莓，主要有北高灌蓝莓中的公爵、蓝乐、耐而逊等，兔眼蓝莓中的亮蓝、香粉蓝等。目前。在北美洲40％的蓝莓用机械采收；81％的蓝莓用于加工，15％鲜销。美国和加拿大已立项进行蓝莓研究，致力于筛选适合当地栽培的新品种。     

北美海棠组培脱菌技术的优化

以北美海棠消毒处理的一年生枝腋芽为试材,采用组织培养技术与抗生素结合的方法,研究了不同抗生素种类与浓度以及不同的处理时间对试材脱菌效果的影响。结果表明:北美海棠外植体在含有羧苄青霉素(250mg·L~(-1))+卡那霉素(50mg·L~(-1))的MS培养基中获得的脱菌苗生长效果最好;经过在增殖培养基上的增殖筛选和3次继代培养,获得的再生苗生长势稳定率最高;经过对再生脱菌苗的细菌学检测,基本没有微生物出现;该试验结果可以为北美海棠的优质苗木繁殖提供技术支撑。     

Changes in land-use/land-cover patterns in Italy and their implications for biodiversity conservation

Land-use/land-cover change is the most important factor in causing biodiversity loss. The Mediterranean region has been affected by antropic disturbance for thousands of years, and is, nowadays, one of the most significantly altered hotspots in the world. However, in the last years a significant increase in forest cover has been measured. These new patterns are independent from planned conservation strategies and appear to have a substantial impact on landscapes and biodiversity. We used three land-use/land-cover maps (from 1960 to 2000) covering the Italian peninsula to analyze the pattern of land-use/land-cover change. We measured an increase in forests, especially in mountains, an increase in artificial areas, especially in coastal zones, and a decrease in pastures. Intensively cultivated areas showed a limited decrease while extensively cultivated ones showed a marked decrease. In the same period mammal and bird species followed a similar pattern, with forest birds, ungulates and carnivores increasing, and typically Mediterranean species decreasing. We suggest that our results may provide important information, which could be useful for conservation planning in the entire Mediterranean hotspot. We suggest that an increasing conservation effort should be made to protect the Mediterranean-type forests and scrublands, as well as traditional agricultural practices. Moreover, future conservation efforts should consider the broad socio-political and ecological processes that are most likely to occur across the whole hotspot, especially along coastal areas, and the network of protected areas should be functionally integrated in a conservation strategy that includes the human-dominated landscape.     

Genetic structure of mulberry from different ecotypes revealed by ISSRs in China: An implications for conservation of local mulberry varieties

Mulberry is a perennial and economically important plant that has traditionally been used for feeding the silkworm. Evaluating genetic relationship is important for long-term improvement in mulberry yield, quality and resistance, and for germplasm conservation and identification. Population structure and genetic diversity of 8 mulberry populations from different ecotypes in China were analyzed by ISSR markers. Twelve ISSR primers generated a total of 83 amplification products, of which 50 were polymorphic, revealing 60.24% polymorphism among 66 mulberry local varieties, the mean PIC value was 0.1469. The total heterozygosity (H_T), heterozygosity within population (H_S), diversity between populations (D_ST) were 0.1600, 0.0851 and 0.0749, respectively. The coefficient of population differentiation (G_ST) was 0.4683, indicating that the variations among populations and those within populations contributed 46.8% and 53.2% to the total heterozygosity, respectively. The gene flow (N_m) was 0.5678, suggesting that genetic drift between populations can caused local genetic differentiation and therefore, population divergence. The mean genetic similarity coefficient was 0.8456, genetic similarity coefficient among 8 mulberry populations ranged from 0.8441 to 0.9640, indicating that genetic diversity of different populations existed variation. A dendrogram of all 66 local varieties of mulberry based on the genetic similarity using ISSR markers was generated by UPGMA cluster method. In the dendrogram, most varieties from the same ecotype clustered together.     

Geographical patterns in openland cover and hayfield mowing in the Upper Great Lakes region: implications for grassland bird conservation

Populations of many grassland bird species such as Grasshopper Sparrow (Ammodramus savannarum), Henslow’s Sparrow (A. henslowii), and Bobolink (Dolichonyx oryzivorus) have experienced considerable declines over the last century. To foster multi-species grassland bird conservation in the Upper Great Lakes (UGL) states of Michigan, Minnesota, and Wisconsin, we quantified geographic patterns within three sub-regional zones (e.g., North, Central, and South) of the UGL. Patterns of interest included the distribution and abundance of openland cover type (including managed pasture-hayland), the distribution, phenology, habitat affinity, and long-term population trends of ten grassland bird species, and (in particular) the geographic patterns in hayfield mowing and the temporal changes in hayfield cover. Approximately 10, 38, and 53% of the UGL openland was proportioned in the North, Central, and South zones, respectively. The distribution of hayland also varied by zone: North, 17%; Central, 46%; and South, 37%. In the central portion of the UGL where the greatest area is devoted to hay production, alfalfa—more intensively managed than mixed-grass hay—predominates. Although we found significance differences (P < 0.05) in hayfield mowing intensity between zones (with the majority of land under relatively low-intensity mowing found in the North Zone, particularly the Upper Peninsula of Michigan) no strong relationships were found between hayfield mowing patterns, other land cover-land use variables, and bird population trends at finer scales of study. Nonetheless, we suggest that the geographic patterns illustrated here provide useful information for grassland bird conservation planning across the UGL.     

Assessing the role of Natura 2000 at maintaining dynamic landscapes in Europe over the last two decades: implications for conservation

Context

The Natura 2000 aims to promote the persistence of biodiversity and traditional uses. European landscapes have, however, undergone large transformations in the past decades, mainly associated with the abandonment of less productive lands concentration of intensive agriculture. These changes could pose management challenges and new opportunities to the achievement of the network´s goals.

Objective

Evaluate changes in land cover within Natura 2000 in the last two decades.

Methods

We use different Corine Land Cover datasets to construct transition matrices of land uses for measuring changes for each Natura 2000 site. We also explore the role of different drivers in observed changes and assess the impacts of these changes in the structure of landscape.

Results

Landscape has been highly dynamic within Natura 2000 in the last two decades with more than 20% undergoing land cover changes. The most systematic transitions involved both, succession processes towards naturalisation in older and more abrupt protected areas (PAs) and anthropization in less steep and more recently designated PAs. Changes across land cover categories had also significant effects on the landscape configuration towards a higher homogenisation.

Conclusions

Two different strategies would be needed to enhance the role of Natura 2000, (i) tighter control to ensure anthropization, mainly intensive agriculture, does not compromise conservation goals within PAs and (ii) tackle more effectively the ecological and socio-economic effects of abandonment in less productive areas to halt loss of key habitats. On the other hand, changes in composition and structure of landscape open new conservation opportunities derived from enhanced connectivity.

     

Spatial and temporal dynamics of habitat availability and stability for a critically endangered arboreal marsupial: implications for conservation planning in a fire-prone landscape

Landscape Ecology - Effective conservation planning for species depends on vegetation models that can capture the dynamics of habitat elements across both spatial and temporal domains....     

Birds in North American Great Lakes coastal wet meadows: is landscape context important?

Landscape context can influence species richness, abundance, or probability of patch-use by birds. Little is known, however, about the effects of landscape context on birds in wetland-dominated landscapes. This lack of knowledge is alarming because many wetlands are threatened by development and other human impacts, while serving critical functions as migratory, breeding and foraging habitat. To address this lack of knowledge, we censused birds in North American Great Lakes coastal wet meadows located along the northern Lake Huron shoreline in Michigan (USA) during 1997 and 1998. Using a suite of multivariate techniques, we first accounted for effects of area and within-patch habitat characteristics before testing for effects of landscape context. Most bird variables were significantly related to landscape context, and two major patterns were apparent. First, avian species richness, abundance, and probability of patch-use by some species were higher for wet meadows located in complex contexts (adjacent to many patch types) compared to simpler contexts (adjacent to only one patch type). Second, these variables were higher for wet meadows located in wetland contexts compared to contexts that were terrestrial and road-impacted, dominated by open water habitats, or dominated by forested wetland habitats. Conservation plans for wetlands have focused on saving large wetlands and creating the vegetative habitat structure required by birds, but they should go further and explicitly consider the landscape context of wetlands as well. Specifically, wetlands located in complex and/or wetland contexts should have a higher conservation value than similar wetlands located in simpler, more terrestrial contexts. This revised version was published online in August 2006 with corrections to the Cover Date.     

Taxon-dependent Scaling: Beetles,Birds, and Vegetation at Four North American Grassland Sites

Because organisms respond to the environment at different scales, it is important to develop ways of determining the appropriate scales for a specific ecological process and organism. We consider whether the relative importance of different scales is associated with organism mobility, and whether this relationship is independent of landscape characteristics. We observed abundances of particular species for vascular plants, ground-dwelling beetles and breeding birds along eight 2-km transects of 40 sampling stations each, distributed over four sites along the regional gradient from shortgrass steppe in central Colorado to tallgrass prairie in central Kansas. For each transect and taxonomic group, the relative importance of factors measured at the trap scale (1 m; soil texture and hardness, vegetation height, bare ground), at the local scale (10 m; density of shrubs and cacti) and at the landscape scale (30 m; Landsat 7 TM spectral bands, slope and elevation) was assessed using hierarchical canonical variance partitioning with forward selection of explanatory variables. Plant, beetle and bird community composition was explained by environmental factors measured at all three scales. Factor influence was more consistent between transects and between plants and beetles for the more homogeneous landscapes of the shortgrass steppe than for the more heterogeneous landscapes of the tallgrass prairie. We conclude that, independent of the mobility of a taxonomic group, factors at several scales are important in explaining community composition. The importance of different scales shifts along a regional gradient, and the variability between sites is high even for nearby sites.     

Expanding the conservation toolbox: conservation planning of multifunctional landscapes

An area of convergence appears to be emerging between the approaches of conservation planning and the concepts of multifunctional landscapes, which if exploited correctly may assist in overcoming the resource and other constraints faced by biodiversity conservation, while at the same time furthering the aims of multifunctional landscapes to improve production abilities and overall sustainability. Using a multi-zone conservation planning approach, we explore the conservation costs, benefits to biodiversity conservation and possible ecosystem service payments associated with various land-use configurations, in the Little Karoo of South Africa, in order to develop and showcase a multifunctional landscape planning approach and its data requirements, as well as the possible cost savings to conservation agencies. The study uses four conservation planning scenarios, five land-use types, their conservation costs and biodiversity benefits, as well as possible payments from carbon sequestration and tourism. We find that the costs and biodiversity benefits associated with different land-uses varies substantially between land-uses, and also spatially within a land-use type. By incorporating this variation into a multi-zone conservation planning approach land-uses can be allocated in a way that achieves biodiversity targets while at the same time reducing costs by up to 50?% when compared with traditional binary approaches to conservation. Despite some challenges presented by cost and ecosystem service value data and the determination of land-use impacts on biodiversity and ecosystem services, the ability of conservation planning approaches to reflect differential contributions of particular land-uses to biodiversity targets and ecosystem services holds much potential for conservation planning, for multifunctional landscape objectives and for growing the resources and partnerships available to the establishment of sustainable and resilient landscapes.     

Changes to the landscape pattern of coastal North Carolina wetlands under the Clean Water Act, 1984–1992

Wetland management in the United States is organized through a permit process that requires a permit be filed with the U.S. Army Corps of Engineers prior to wetland alteration. A collection of these permits from 1984 through 1992 was analyzed in conjunction with classified Landsat Thematic Mapper data from 1984 and 1992 in order to quantify changes to wetland habitat in the study area in coastal North Carolina. The wetland management process in the U.S. focuses on a site-by-site review, possibly overlooking important changes to wetlands at the landscape-scale. These the two datasets were used to determine if wetland habitat loss was occurring at permit sites, but also to determine if landscape-scale wetland fragmentation and reorganization were occurring in the area surrounding each permit site under the wetland management process. The use of these two datasets attempted to span two scales: the site-specific scale often used in the management of wetlands, and the landscape-scale where effects of such management are evident. Important conclusions from the research include the following. First, while several sources imply that coastal wetlands are disproportionately protected as a result of the widespread recognition of their habitat value, estuarine wetlands were altered much more frequently in the study area than their inland counterparts. Second, despite federal level efforts that require compensatory mitigation when wetland habitat is lost, such mitigation was required in only three percent of permits, ensuring wetland loss. Third, correlation between estimates of wetland loss from the Permit Record and from the remotely sensed record was minimal, highlighting the problems inherent to wetland delineation and implying alterations to habitat not evidenced in the permit record. Finally, landscape-scale changes of loss, fragmentation and habitat reorganization have occurred in estuarine emergent wetland habitat in areas adjacent to several permit sites, implying unanticipated additional impacts to permitted actions. Wetland loss at the permit site occurred with additional fragmentation in 80 percent of the sites examined. The results highlight the lack of agreement between management and landscape-scale wetland structure, function and change, and imply the importance of examining the spatial context of permit sites in the permit review and evaluation procedure.     

Spatiotemporal dynamics of housing growth hotspots in the North Central U.S. from 1940 to 2000

Housing growth is a primary form of landscape change that is occurring throughout the world. Because of the ecological impacts of housing growth, understanding the patterns of growth over time is imperative in order to better inform land use planning, natural resource management, and conservation. Our primary goal was to quantify hotspots of housing growth in the North Central United States over a 60-year time frame (1940–2000) using a spatial statistical approach. Specifically, our objectives were to: (1) determine where housing growth hotspots exist; (2) determine if hotspots are changing in space and over time; and, (3) investigate if hotspots differ based upon the type of measurement and scale of analysis. Our approach was based on a spatial statistical framework (Getis-Ord G* statistic) that compared local housing growth patterns with regional growth rates. Over the 60-year period the number and mean area of hotspots, measured both as absolute and percent growth, remained largely constant. However, total area of all hotspots increased significantly over time as measured by absolute growth. Spatially, the hotspots shifted over time and exhibited different patterns based upon the measurement. Absolute growth hotspots exhibited patterns of expanding sets of rings around urban centers, whereas percent growth hotspots exhibited both expanding rings and shifting locations throughout rural locations. When increasing the neighborhood size used to discern hotspots from 5 to 50 km, the number of hotspots decreased while their size increased. Regardless of neighborhood size, ∼95 and ∼88% of the landscape, as measured by absolute and percent growth, respectively, never contained a hotspot. Overall our results indicate that housing growth is occurring at distinct locations on the landscape, which change in space and time, and are influenced by the scale of analysis and type of measure. In general these results provide useful information for the natural resource, planning, and policy communities.     

Finding the functional grain: comparing methods for scaling resistance surfaces

The influence of landscape features on the movement of an organism between two point locations is often measured as an effective distance. Typically, raster models of landscape resistance are used to calculate effective distance. Because organisms may experience landscape heterogeneity at different scales (i.e. functional grains), using a raster with too fine or too coarse a spatial grain (i.e. analysis grain) may lead to inaccurate estimates of effective distance. We adopted a simulation approach where the true functional grain and effective distance for a theoretical organism were defined and the analysis grains of landscape connectivity models were systematically changed. We used moving windows and grains of connectivity, a recently introduced landscape graph method that uses an irregular tessellation of the resistance surface to coarsen the landscape data. We then used least-cost path metrics to measure effective distance and found that matching the functional and analysis grain sizes was most accurate at recovering the expected effective distance, affirming the importance of multi-scale analysis. Moving window scaling with a maximum function (win.max) performed well when the majority of landscape structure influencing connectivity consisted of high resistance features. Moving window scaling with a minimum function (win.min) performed well when the relevant landscape structure consisted of low resistance regions. The grains of connectivity method performed well under all scenarios, avoiding an a priori choice of window function, which may be challenging in complex landscapes. Appendices are provided that demonstrate the use of grains of connectivity models.     

Physical influences of landscape on a large-extent ecological disturbance: the northeastern North American ice storm of 1998

The 1998 ice storm was a large-extent ecological disturbance that severely affected the eastern Adirondack forests of northern New York. Ice damage produced widespread breakage of limbs and trunks in susceptible trees. Although ice storms are common within northeastern North American forests, the magnitude and extent of the 1998 storm far exceeded damage caused by typical ice storms in the recent past. While plot and stand-scale ecological impacts of ice storms have received attention insofar as tree species vulnerability, stand age susceptibility, and microhabitat alterations, larger-extent damage patterns have not been previously evaluated. The normalized difference vegetation index (NDVI) was employed to assess forest vigor and canopy density in atmospherically corrected Landsat Thematic Mapper (TM) satellite imagery of the Adirondacks. Digital change analysis of the baseline forest condition (1990 NDVI data), and the condition encountered in a post-storm image (1998 NDVI data) was conducted. Forest damage was separated from natural variations in canopy reflectance by employing a generalized linear model that incorporated in situ measurements. A robust empirical variogram analysis revealed that locations of tree damage were significantly correlated for distances up to 300 meters. Intensely-damaged forest exhibited greater spatial dependence, but over a smaller distance. Canopy damage was not greater proximate to stream and forest boundaries, and did not follow our hypothesis of decreasing damage with distance from the boundary. Overall, we show that local topography (elevation and aspect), forest composition (deciduous or coniferous), and the meteorological characteristics of the disturbance event acted together to determine the spatial extent of ice storm damage.This revised version was published online in May 2005 with corrections to the Cover Date.     

HexSim: a modeling environment for ecology and conservation

Context

Simulation models are increasingly used in both theoretical and applied studies to explore system responses to natural and anthropogenic forcing functions, develop defensible predictions of future conditions, challenge simplifying assumptions that facilitated past research, and to train students in scientific concepts and technology. Researcher’s increased use of simulation models has created a demand for new platforms that balance performance, utility, and flexibility.

Objectives

We describe HexSim, a powerful new spatially-explicit, individual-based modeling framework that will have applications spanning diverse landscape settings, species, stressors, and disciplines (e.g. ecology, conservation, genetics, epidemiology). We begin with a model overview and follow-up with a discussion of key formative studies that influenced HexSim’s development. We then describe specific model applications of relevance to readers of Landscape Ecology. Our goal is to introduce readers to this new modeling platform, and to provide examples characterizing its novelty and utility.

Conclusions

With this publication, we conclude a > 10 year development effort, and assert that our HexSim model is mature, robust, extremely well tested, and ready for adoption by the research community. The HexSim model, documentation, worked examples, and other materials can be freely obtained from the website www.hexsim.net.

     

Response of North American ecosystem models to multi-annual periodicities in temperature and precipitation

Ecosystem models typically use input temperature and precipitation data generated stochastically from weather station means and variances. Although the weather station data are based on measurements taken over a few decades, model simulations are usually on the order of centuries. Consequently, observed periodicities in temperature and precipitation at the continental scale that have been correlated with largscale forcings, such as ocean-atmosphere dynamics and lunar and sunspot cycles, are ignored. We investigated how these natural climatic fluctuations affect aboveground biomass in ecosystem models by incorporating some of the more pronounced continental-scale cycles in temperature (4, 11, 80, 180 year periods) and precipitation (11 and 19 year periods) into models of three North American forests (using LINKAGES) and one North American grassland (using STEPPE). Even without inclusion of periodicities in climate, long-term dynamics of these models were characterized by internal frequencies resulting from vegetation birth, growth and death processes. Our results indicate that long-term temperature cycles result in significantly lower predictions of forest biomass than observed in the control case for a forest on a biome transition (northern hardwoods/boreal forest). Lower-frequency, higher-amplitude temperature oscillation caused amplification of forest biomass response in forests containing hardwood species. Shortgrass prairie and boreal ecosystems, dominated by species with broad stress tolerance ranges, were relatively insensitive to climatic oscillations. Our results suggest periodicities in climate should be incorporated within long-term simulations of ecosystems with strong internal frequencies, particularly for systems on biome transitions.