Connectivity in Heterogeneous Landscapes: Analyzing the Effect of Topography

Animal response to landscape heterogeneity directs dispersal and affects connectivity between populations. Topographical heterogeneity is a major source of landscape heterogeneity, which is rarely studied in the contexts of movement, dispersal, or connectivity. The current study aims at characterizing and quantifying the impacts of topography on landscape connectivity. We focus on ‘hilltopping’ behavior in butterflies, a dispersal-like behavior where males and virgin females ascend to mountain summits and mate there. Our approach integrates three elements: an individual-based model for simulating animal movements across topographically heterogeneous landscapes; a formula for the accessibility of patches in homogenous landscapes; and a graphical analysis of the plots of the simulation-based vs. the formula-based accessibility values. We characterize the functional relationship between accessibility values and landscape structure (referred to as ‘accessibility patterns’) and analyze the influence of two factors: the intensity of the individuals’ response to topography, and the level of topographical noise. We show that, despite the diversity of topographical landscapes, animal response to topography results in the formation of two, quantifiable accessibility patterns. We term them ‘effectively homogeneous’ and ‘effectively channeled’. The latter, in which individuals move toward a single summit, prevails over a wide range of behavioral and spatial parameters. Therefore, ‘channeled’ accessibilities may occur in a variety of landscapes and contexts. Our work provides novel tools for understanding and predicting accessibility patterns in heterogeneous landscapes. These tools are essential for linking movement behavior, movement patterns and connectivity. We also present new insights into the practical value of ecologically scaled landscape indices.     

Scale-dependent determinants of heterogeneity in fire frequency in a coniferous boreal forest of eastern Canada

Despite the recognized importance of fire in North American boreal forests, the relative importance of stochastic and determinist portions of intra-regional spatial variability in fire frequency is still poorly understood. The first objective of this study is to identify sources of spatial variability in fire frequency in a landscape of eastern Quebec’s coniferous boreal forest. Broad-scale environmental factors considered included latitude, longitude, human activities and belonging to a given bioclimatic domain, whereas fine-scale factors included slope, position on the slope, aspect, elevation, surficial deposit and drainage. The average distance to waterbodies was also considered as a potential intermediate-scale source of variability in fire frequency. In order to assess these environmental factors’ potential influence, they were incorporated into a proportional hazard model, a semi-parametric form of survival analysis. We also used a digital elevation model in order to evaluate the dominant aspect within neighborhoods of varying sizes and successively incorporated these covariates into the proportional hazard model. We found that longitude significantly affects fire frequency, suggesting a maritime influence on fire frequency in this coastal landscape. We also found that position on the slope was related to fire frequency since hilltops and upperslopes were subject to a lower fire frequency. Dominant aspect was also related to fire frequency, but only when characterized within a neighborhood delimited by 4,000 to 10,000-m radii (5,027–31,416 ha). A 2–6-fold variation in fire frequency can be induced by geographic and topographic contexts, suggesting a substantial intra-regional heterogeneity in disturbance regime with potential consequences on forest dynamics and biodiversity patterns. Implications for forest management are also briefly discussed. Electronic supplementary material The online version of this article (doi: ) contains supplementary material, which is available to authorized users.     

A reverse keystone species affects the landscape distribution of woodland avifauna: a case study using the Noisy Miner (<Emphasis Type="Italic">Manorina melanocephala</Emphasis>) and other Australian birds

We explored the effects of a purported ‘reverse keystone species’, the Noisy Miner (Manorina melanocephala) using a long-term, large-scale dataset. Specifically, we identify whether this aggressive bird affects the landscape distribution patterns of other avifauna, by displacing them into, or restricting their distribution to, less productive areas, and in so doing, adheres to ‘isoleg theory’. We sought to determine the effect of abundance of the Noisy Miner on the abundance of other birds (individual species and groups), and determine whether that effect was consistent with varying site productivity, using a negative binomial distribution with a logarithmic link function, and an offset variable to account for variations in search effort. Relationships between abundance of Noisy Miners and habitat variables were examined using a Poisson distribution with a logarithmic link function scaled for extra-variation (quasi-Poisson regression). We demonstrate that when Noisy Miner abundance is low, many small passerine species are more abundant on high productivity sites. However, as Noisy Miner abundance increases, small passerine abundance decreases, with this decrease most apparent on productive sites. The same patterns were not evident for birds considered ‘non-competitors’ of the Noisy Miner. We identify that both site productivity and vegetation structure influence the abundance of the Noisy Miner. We reveal that the species increasingly tolerates ‘less desirable’ habitat attributes with increasing site productivity. The preference of the Noisy Miner for productive areas is likely to have deleterious impacts on the long-term survival and reproductive success of other Australian woodland bird species, many of which have already undergone severe declines.     

The ‘habitat backbone’ as strategy to conserve pioneer species in dynamic port habitats: lessons from the natterjack toad (Bufo calamita) in the Port of Antwerp (Belgium)

Biodiversity conservation in economic areas like ports has recently become more important in the European Union due to a stricter interpretation of nature protection laws. In this study we develop a planning and design strategy—the ‘habitat backbone’—with which to support the long-term survival of pioneer species that occur in ports and have low dispersal abilities. For those species, long-term survival in port areas is uncertain because supply of their habitats (on vacant lots) is capricious and depends on land use dynamics. By gaining knowledge about spatial and temporal characteristics of these dynamics we were able to develop a solution to conserve such species. Our solution is based on the creation of permanent habitat—defined as a ‘backbone’—on (semi-) public land with an overall carrying capacity sufficient to support persistent populations. This best ensures long-term survival, and the backbone may also act as refugium. Satellite populations that emerge on adjacent vacant lots will thereby add to the persistence of the overall metapopulation. Management of permanent habitat is focused on retaining early-successional stages of vegetation. Implementing this strategy in the case of the natterjack toad in the Port of Antwerp taught us that realization of a habitat backbone is possible only if landowners, local governments and environmental NGOs cooperate. In the case at hand, such cooperation resulted in a plan that should ensure a coherent and persistent habitat network in which a chorus of some 1,400 natterjack toads could be accommodated—more than the number of toads currently observed. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Large-scale effects on the spatial distribution of seabirds in the Northwest Atlantic

Scale questions are particularly important for organisms which range over large areas, as pelagic seabirds do. The investigations of scale are of practical importance for describing patch size of predator and prey, determining the appropriate scale of study and correcting survey transects. We conducted this study in order to explore a substantially wider diversity of spatial scales than has previously been attempted in the pelagic bird literature. As an example of large monitoring datasets dealing with seabirds, we use the PIROP (Programme intégré pour le recherche des oiseaux pélagiques) data set to investigate relevant large scale issues for these species in the Northwestern Atlantic. We analyzed autocorrelation within selected winter and summer transects, and for 1 degree analysis units (‘bins’) for data collected June–August 1966–1992. We also investigated effects of the analysis unit on counting results and on the links between seabirds and their environment (depth, sea surface salinity and temperature). We selected scales of 1, 2, 5 and 10 degrees analysis units; an ecological mapping scale (‘Banks’ not deeper than 200 m) and a political scale (management convention zones of the North Atlantic Fisheries Organization, NAFO) were also included. Using ‘binning’ of various scales, our results show that the Coefficient of Variation for seabird abundances varies among aggregation scales, and that seabird associations with their environment can show scale effects. Autocorrelation of analysis units indicated some distinct larger scale patch sizes for particular species during the breeding season.     

Spatial Concepts in Landscape Analysis and Policy: Some Implications of Globalisation

Globalisation accelerates the dynamics of the network society and economy, in which distant relationships become functionally more significant than local landscape relationships. This presents challenges and opportunities for landscape analysis. Using social scientific concepts of global and local space, and ecological concepts of hierarchy, two qualitative case studies are undertaken of urban fringe landscapes in Copenhagen, Denmark, and Christchurch, New Zealand. They reveal a convergence of landscape pattern over time, but this disguises significant differences in underlying socio-economic process and institutional response. There are several implications for landscape analysis and policy. First, there is a need for studies grounded in particular landscapes that acknowledge both local spatial landscape relationships and non spatial ‘global’ processes. Second, the transformation of landscapes through urbanisation provides a useful focus for the connection of landscape ecological understanding of landscape systems with social scientific understanding of human agency and social structure. Third, there is a significant challenge in how to develop local and regional institutions and policies that have the capacity to utilise and apply these diverse analytical perspectives.     

Multi-scale site and landscape effects on the vulnerable superb parrot of south-eastern Australia during the breeding season

The threatened superb parrot of south-eastern Australia exemplifies many of the challenges associated with research on wide-raging organisms which live ‘off-reserve’. Challenges include that most land is privately owned and that landscape use by such organisms does not always conform to traditional schematic and categorical landscape/fragmentation models. A multi-scale approach for embedding the detection of site-level and landscape context effects into landscape sampling design and subsequent statistical analysis is presented. The superb parrot was found scattered at varying densities throughout the agricultural landscapes of the South-West Slopes, much of which was privately owned. It responded to site-level variables and the surrounding landscape context. Overall, the superb parrot favoured lower elevation sites which were dominated by scattered, open woodlands, where Blakely’s red gum was a significant component. Mean plant productivity within 2 km, levels of woody tree cover within 3 km and (with caveats) length of roads within 3 km had a major effect on site-level response, indicating conditions in the surrounding local landscape are important to the superb parrot. This multi-scale response requires a multi-scale conservation and restoration strategy. The importance of open tree cover and amounts of Blakely’s red gum are a matter for concern, due to a general lack of tree regeneration and the particular susceptibility of Blakely’s red gum to dieback. The scattered trees in the agricultural matrix were important to the superb parrot, suggesting that it views these landscapes as a continuum of usable habitat. Strategies for restoration of larger habitat remnants should also include regeneration of trees in scattered pattern in the wider landscape, and Blakely’s red gum should be part of any strategy along with other key species such as yellow and white box. The landscape sampling approach successfully addressed the challenges of whole-landscape research. This highlights the value of ‘off-reserve’ studies across whole landscapes.     

Small-scale effects of historical land use and topography on post-cultural tree species composition in an Alpine valley in southern Switzerland

Investigations of spatial patterns in forest tree species composition are essential in the understanding of landscape dynamics, especially in areas of land-use change. The specific environmental factors controlling the present patterns, however, vary with the scale of observation. In this study we estimated abundance of adult trees and tree regeneration in a Southern Alpine valley in Ticino, Switzerland. We hypothesized that, at the present scale, spatial pattern of post-cultural tree species does not primarily depend on topographic features but responds instead to small-scale variation in historical land use. We used multivariate regression trees to relate species abundances to environmental variables. Species matrices were comprised of single tree species abundance as well as species groups. Groups were formed according to common ecological species requirements with respect to shade tolerance, soil moisture and soil nutrients. Though species variance could only be partially explained, a clear ranking in the relative importance of environmental variables emerged. Tree basal area of formerly cultivated Castanea sativa (Mill.) was the most important factor accounting for up to 50% of species’ variation. Influence of topographic attributes was minor, restricted to profile curvature, and partly contradictory in response. Our results suggest the importance of biotic factors and soil properties for small-scale variation in tree species composition and need for further investigations in the study area on the ecological requirements of tree species in the early growing stage.     

Mapping Spatial Patterns with Morphological Image Processing

We use morphological image processing for classifying spatial patterns at the pixel level on binary land-cover maps. Land-cover pattern is classified as ‘perforated,’ ‘edge,’ ‘patch,’ and ‘core’ with higher spatial precision and thematic accuracy compared to a previous approach based on image convolution, while retaining the capability to label these features at the pixel level for any scale of observation. The implementation of morphological image processing is explained and then demonstrated, with comparisons to results from image convolution, for a forest map of the Val Grande National Park in North Italy.     

Aspects influencing the selection of representative urbanization measures to quantify urban–rural gradients

The quantification of urban–rural gradients using urbanization measures has become standard practice in many urban ecological studies. Nonetheless, the choice of urbanization measures for a specific urban gradient still remains problematic. Increasing numbers of papers stress the importance of comparative urban ecological research, in an attempt to contribute to an understanding of the ecology ‘of’ cities. This implies that research in diverse urban areas globally should be comparable. This study follows an approach to quantify the urban–rural gradient in Klerksdorp previously followed in Melbourne, Australia with the goal to help elucidate the viability of creating a standard set of urbanization measures that is useful across continents. Satellite imagery and spatial analysis were used to calculate the values of 12 urbanization measures across a 900 km² landscape grid. Principal components analysis is commonly used to identify smaller subsets of measures to quantify urban–rural gradients. The results of this study indicate that factor analysis is more suitable than principal components analysis and ideal in identifying these independent measures of urbanization. The factor analysis revealed that landscape structure and demographic attributes are both essential characteristics of a city that needs to be accounted for in the choice of urbanization measures. Additionally, we identified seven aspects influencing the direct comparison of cities, namely: scale of analysis, spatial resolution, classification typology, accuracy of input data, specific measure equations, the type of statistical analysis and the habitat context. These aspects must be taken into consideration and resolved before effective comparative gradient research between cities can be achieved.     

Model description of dynamics of disturbance and recovery of natural landscapes

We consider the dynamic simulation model of landscapes proposed by Turner et al. (1993). In this model a landscape, represented by a square grid of 100×100 cells, is exposed to disturbances of a fixed size at random locations at specified time intervals. The affected area recovers through a series of seral stages and achieves a mature stage unless it is affected again by successive disturbances. Two non-dimensional parameters, determining the dynamics of the model, are T, the ratio of the disturbance interval to the time of recovery and S, the ratio of the size of the disturbance to the size of the landscape. The main outcomes of analysis are the means and standard deviations of the areas occupied by different seral stages. We show that these characteristics of the system can be calculated analytically. This facilitates the understanding of the results of the computer experiments, the analysis of the asymptotic behaviour of the system (for example when the disturbances become increasingly small but very frequent, T,S1) and of more complex regimes of external disturbances, e.g., of the combined effects on a landscape from several types of disturbances with different spatial and time scales.     

Landscape improvement, or ongoing degradation – reconciling apparent contradictions from the arid rangelands of Western Australia

Recent quantitative site-based monitoring and qualitative aerial and ground traverses provide contrasting assessments of the health of much of the arid shrublands of Western Australia extensively grazed by livestock (‘rangelands’). Although these results seem incompatible, we explain the apparent contradictions based on landscape succession processes operating at multiple levels of ecological organisation. Specifically, we suggest that the intact areas in which site-based monitoring is conducted are contracting as catchment canalisation and desiccation increase. However, the impacts of these processes have not yet become manifest at the site scale. The site-based system addresses important regional questions. These relate to the large, relatively intact areas away from most active surface flows, which should be a focus for resource conservation, given practical limits to repairing widespread degradation with low management inputs. We provide a complementary set of questions to provide a more comprehensive audit of rangeland dynamics in the context of underlying hierarchical landscape patterns and processes that might threaten intact areas. We recognise the need to match questions and levels of ecological organisation and the implications these have for sampling. We also recognise the difficulty in producing concise statements of change for clients when reporting on complex ecological issues and processes. Without a clearly articulated, and well understood, hierarchical model of pattern and process within which apparently contradictory findings can be reported meaningfully, policy makers may be confused by the results, with the consequent risk of policy inaction.     

Nicht-invasive Zucker- und Festigkeitsmessung von Früchten

Zusammenfassung Ziel dieser methodischen Arbeit ist der Vergleich der konventionellen, destruktiven Bestimmung der Fruchtfestigkeit mit dem Hand-Penetrometer an geschälten Früchten bzw. mit dem ART-Penetrometer nach Ausstanzen der Fruchtschale mit dem neuen nicht-invasiven „Intelligent Firmness Detector“ (IFD). Verwendet wurden ausgelagerte Apfelfrüchte der Sorten ‘Golden Delicious’, ‘Braeburn’, ‘Topaz’ und ‘Elstar’, die im Februar 2004 zur Sortierung und zum Verkauf anstanden, und gekaufte Früchte.Der IFD misst – mit Hilfe eines Drucksensors – die Fruchtelastizität bis zu 20× entlang des Fruchtäquators, während sich die Frucht dreht. Die Werte werden automatisch korrigiert, wenn sich eine Frucht seitlich verdreht und der Apfelstiel gemessen wird. Wiederholte Messungen der gleichen Frucht zeigten die geringste Variabilität bei festen Apfelfrüchten, wobei die Abweichung mit±1–2 Einheiten des Festigkeitsindexes oder umgerechnet ±0,2 kg/cm² gering war.Die genaueste Differenzierung und beste Korrelation zwischen dem IFD und den herkömmlichen, destruktiven Methoden bestand bei festeren, vermarktungsfähigen Äpfeln wie ‘Braeburn’ über 6 kg/cm². Eine Ursache kann die einmalige Eichung des IFD mit einem Hartgummiball in oberen Messbereich sein. Die geringere Korrelation zwischen dem IFD und den beiden destruktiven Methoden bei weichen Früchten unter 4 kg/cm² wird darauf zurückgeführt, dass die Festigkeitsmessung mit dem Hand-Penetrometer durch das vorherige Schälen genauer ist, während der Stempel im ART – System die Schale erst eindrückt und dann ausstanzt bevor er das Fruchtfleisch durchdringt und die Festigkeit somit ebenso überschätzt.Die nicht-invasive Zuckerbestimmung mit dem „Intelligent Fruit Analyser“ (IFA) beruht auf bis zu fünf optischen Transmissionsmessungen pro Frucht im Bereich 400–1100 nm. Alle Transmissionsspektren zeigten die typische Chlorophyllabsorption bei 672–679 nm und darüber im NIR – Bereich zwei Spitzenwerte bei 710–730 nm und 814–824 nm. Bei diesem Verfahren wird die ganze Frucht, d. h. z. B. ein Apfel, eine Kiwi oder Apfelsine durchleuchtet. Die VIS/NIR – Transmissionsspektren werden mit einem Siliziumdetektor mit Diodenarray unter der Frucht aufgezeichnet, einer Faktorenanalyse unterzogen und vor der Messreihe mit den im Refraktometer gemessenen Zuckergehalten der gleichen Früchte korreliert. Die Korrelation stieg bei nur 50 Früchten von r² = 0,62 bei ‘Elstar’ durch eine größere Stichprobe auf r² = 0,84. Bei derart hohen r²-Werten betrug die Genauigkeit der Zuckerbestimmung mit dem IFA ca. 4%, d. h. ±0,65°Brix bei Zuckergehalten in Äpfeln von 14–19°Brix.Beim Zuckermodul IFA ist entweder eine umfangreiche, repräsentative Stichprobe oder sowohl für jede Sorte als auch für unterschiedliche Standorte eine eigene Korrelation notwendig, die der Hersteller berechnet und im IFA speichert. Bei beiden Bestimmungen mit dem IFD und IFA traten keine Druckstellen oder sonstige Schäden an den untersuchten Früchten auf.     

A leakiness index for assessing landscape function using remote sensing

The cover, number, size, shape, spatial arrangement and orientation of vegetation patches are attributes that have been used to indicate how well landscapes function to retain, not ‘leak’, vital system resources such as rainwater and soil. We derived and tested a directional leakiness index (DLI) for this resource retention function. We used simulated landscape maps where resource flows over map surfaces were directional and where landscape patch attributes were known. Although DLI was most strongly related to patch cover, it also logically related to patch number, size, shape, arrangement and orientation. If the direction of resource flow is multi-directional, a variant of DLI, the multi-directional leakiness index (MDLI) can be used. The utility of DLI and MDLI was demonstrated by applying these indices to three Australian savanna landscapes differing in their remotely sensed vegetation patch attributes. These leakiness indices clearly positioned these three landscapes along a function-dysfunction continuum, where dysfunctional landscapes are leaky (poorly retain resources). This revised version was published online in July 2006 with corrections to the Cover Date.     

Mapping hotspots of multiple landscape functions: a case study on farmland afforestation in Scotland

Many conservation and restoration efforts in developed countries are increasingly based on the premise of recognising and stimulating more ‘multi-functionality’ in agricultural landscapes. Public policy making is often a pragmatic process that involves efforts to negotiate trade-offs between the potentially conflicting demands of various stakeholders. Conservationists’ efforts to influence policy making, can therefore benefit from any tool that will help them to identify other socio-economic functions or values that coincide with good ecological conservation options. Various types of socio-economic objectives have in recent years been mapped across landscapes and so there are now important opportunities to explore the spatial heterogeneity of these diverse functions across the wider landscape in search of potential spatial synergies, i.e. ‘multiple win locations’ or multifunctional ‘hotspots’. This paper explores the potential occurrence of such synergies within the agricultural landscape of northeast Scotland and evaluates an existing woodland planting policy using and combining three different policy objectives. Our results show that there are indeed broad areas of the studied landscape where multiple objectives (biodiversity, visual amenity and on-site recreation potential) could be achieved simultaneously (hotspots), and that the case study which we evaluate (the Farm Woodland Premium Scheme) could be much better spatially targeted with regards to each individual objective as well as with regards to these hotspots of multifunctionality.

Landscape – What’s in it? Trends in European Landscape Science and Priority Themes for Concerted Research

Reflecting on the other papers in this special issue, this synopsis characterises some essential trends in European Landscape Ecology, including the challenges it is facing in society. It describes the various perspectives on the ‘contents’ of landscape that are currently being practiced, and especially considers the notion of ‘environment’ as something intrinsic to human activity. Landscape classification and typology are discussed in their potential but limited use for landscape science. The specificity of the European approach appears to be related to the large diversity of cultural landscapes, currently losing their functional ties with the land-use systems that had formed them. European landscape research reports show a large commitment to this decreasing diversity, a dedication characterised by a strong sense of ‘loss and grief’. On the other hand, it is concluded that European landscape research has a specific niche with a clear focus on applied landscape studies explicitly including people’s perceptions and images, as well as the participation of the public and stakeholders. Since globalisation tends to reinforce the detachment of people from their environment; an increased effort is needed to compensate for this effect, and therefore the consideration of the various dimensions of the landscape is today more pertinent than ever. Meeting the challenges of present landscapes, in the face of new multifunctional demands in old diverse landscapes, requires more than before the combination of various perspectives and methods, and of various scales of application, in order to design innovative and adaptive paths for the future.     

Textural Ordination Based on Fourier Spectral Decomposition: A Method to Analyze and Compare Landscape Patterns

We propose an approach to texture characterization and comparison that directly uses the information of digital images of the earth surface without requesting a prior distinction of structural ‘patches’. Digital images are partitioned into square ‘windows’ that define the scale of the analysis and which are submitted to the two-dimensional Fourier transform for extraction of a simplified textural characterization (in terms of coarseness) via the computation of a ‘radial’ power spectrum. Spectra computed from many images of the same size are systematically compared by means of a principal component analysis (PCA), which provides an ordination along a limited number of coarseness vs. fineness gradients. As an illustration, we applied this approach to digitized panchromatic air photos depicting various types of land cover in a semiarid landscape of northern Cameroon. We performed ‘textural ordinations’ at several scales by using square windows with sides ranging from 120 m to 1 km. At all scales, we found two coarseness gradients (PCA axes) based on the relative importance in the spectrum of large (> 50 km⁻¹), intermediate (30–50 km⁻¹), small (10–25 km⁻¹) and very small (<10 km⁻¹) spatial frequencies. Textural ordination based on Fourier spectra provides a powerful and consistent framework to identifying prominent scales of landscape patterns and to compare scaling properties across landscapes.     

Untersuchungen zum Auftreten von Druckstellen an Äpfeln nach der Auslagerung

Zusammenfassung Es wurde untersucht, welche Faktoren die Empfindlichkeit von ?pfeln für Druckstellen unmittelbar nach der CA/ULO-Lagerung (CA = Controlled Atmosphere, ULO = Ultra Low Oxygen) beeinflussen. Früchte der Sorten ‘Golden Delicious’ und ‘Jonagold’ wurden nach der CA/ULO-Lagerung für fünf Tage bei vier verschiedenen Nachlagerungsbedingungen (kühl in und ohne Folienbeutel, warm in und ohne Folienbeutel) aufbewahrt. Direkt nach der Auslagerung, ein Tag und fünf Tage sp?ter wurden die ?pfel mittels zwei Apparaturen unterschiedlichen Belastungen ausgesetzt, um Druckstellen zu erzeugen. Weitere gemessene Parameter waren die Fruchtfleischfestigkeit, der Gelbwert, der Gewichtsverlust, der Zellbruchpunkt und die Schalenbruchfestigkeit. Das Ausma? der Druckstellen nahm mit steigender Belastung der Früchte zu. Die warm gelagerten Früchte zeigten mit zunehmender Zeit der Nachlagerung eine geringere Druckstellenempfindlichkeit. Die kühl gelagerten Früchte der Sorte ‘Golden Delicious’ zeigten eine Zunahme der Druckstellenempfindlichkeit im Verlauf der Nachlagerung, die der Sorte ‘Jonagold’ eine Abnahme oder keine Ver?nderung. Ein Zusammenhang zwischen der Druckstellenempfindlichkeit und der Fruchtfleischfestigkeit, dem Zellbruchpunkt oder der Schalenbruchfestigkeit wurde nicht festgestellt.      

Animal movements and population dynamics in heterogeneous landscapes

Organisms respond to environmental heterogeneity at different scales and in different ways. These differences are consequences of how the movement characteristics of animals—their movement rates, directionality, turning frequencies, and turning angles—interact with patch and boundary features in landscape mosaics. The interactions of movement patterns with landscape features in turn produce spatial patterns in individual space-use, population dynamics and dispersion, gene flow, and the redistribution of nutrients and other materials. We describe several theoretical approaches for modeling the diffusion, foraging behavior, and population dynamics of animals in heterogeneous landscapes, including: (1) scaling relationships derived from percolation theory and fractal geometry, (2) extensions of traditional patch-based metapopulation models, and (3) individual-based, spatially explicit models governed by local rules. We conclude by emphasizing the need to couple theoretical models with empirical studies and the usefulness of ‘microlandscape’ investigations.