Spatial theory in early conservation design: examples from Aldo Leopold’s work

Aldo Leo­pold is well known in North America as a conservationist, author, and promoter of the Land Ethic. Although Leo­polds work is rarely included in the realm of landscape ecology, he left several illustrations of an early spatial theory for conservation. While European geographer Troll published the term landscape ecology in 1939, Leo­pold was discovering the role of spatial configuration in European working landscapes, and began to apply the landscape ecology concepts to wildlife management and cooperative conservation in the US. With his own spatial language he wrote, mapped, and applied elements of pattern, process, and connectedness in the landscape. In this perspective piece I use three examples from Leo­polds work to demonstrate his contribution to spatial theory in early conservation design. First, this paper deciphers spatial elements conveyed through Leo­polds writing, drawing, and teaching in the early 1930s. Second, I re-interpret Leo­polds observations of the spatial design of remises from his visit to Silesia, Europe. Third, I show how the lessons from Silesia were applied to a landscape in Wisconsin, USA, involving both farmers and townspeople in cooperative implementation of a remise system. Collectively, a new perspective emerges on the early dialogue of landscape ecology and conservation across continents.This revised version was published online in May 2005 with corrections to the Cover Date.     

Landscape graphs: Ecological modeling with graph theory to detect configurations common to diverse landscapes

In view of the bewildering diversity of landscapes and possible patterns therein, our objectives were to see if a useful modeling method for directly comparing land mosaics could be developed based on graph theory, and whether basic spatial patterns could be identified that are common to diverse landscapes. The models developed were based on the spatial configuration of and interactions between landscape elements (ecosystems, land uses or ecotopes). Nodes represented landscape elements and linkages represented common boundaries between elements. Corridors, corridor intersections, and the matrix were successfully incorporated in the models. Twenty-five landscape graphs were constructed from aerial photographs chosen solely to represent a breadth of climates, land uses and human population densities. Seven distinctive clusters of nodes and linkages were identified and common, three of which, in the forms of a spider, necklace and graph cell, were in >90% of the graphs. These represented respectively the following configurations of patches, corridors and matrix: (1) a matrix area surrounding or adjoining many patches; (2) a corridor bisecting a heterogeneous area; and (3) a unit in a network of intersecting corridors. The models also indicated that the connectivity or number of linkages for several common elements, such as fields and house clearings, was relatively constant across diverse landscapes, and that linear shaped elements such as roads and rivers were the most connected. Several additional uses of this graph modeling, including compatibility with systems dynamics models, are pinpointed. Thus the method is useful in allowing simple direct comparisons of any scale and any landscape to help identify patterns and principles. A focus on the common and uncommon configurations should enhance our understanding of fluxes across landscapes, and consequently the quality of land planning and management.     

A proximity-based approach to assessing habitat

Planning for either a single species, multiple species, or ecosystems is greatly dependent on spatial interactions in the landscape. Problems exist for evaluating wildlife habitat changes over large ranges of space and time. This paper illustrates the use of Geographic Information Systems (GIS) to evaluate habitat for a single species, ruffed grouse (Bonasa umbellus), following a time series of forest harvests. A habitat suitability model for ruffed grouse is utilized on a two-township study area in north-central Minnesota to assess the habitat suitability changes over time using an even-aged area-control harvesting plan. The results are presented as a habitat quality change map and a contingency table, representing the movement of habitat class areas between time periods resulting from the proposed harvesting. We developed a neighborhood definition to allow for spatially varying habitat values. This work illustrates the ability to look ahead and around in estimating the impact on wildlife habitat resulting from alternative future management activities.Now with the U.S. Forest Service, Sitka, AK 99835.     

Effects of patch shape on the number of organisms

This study examined effects of habitat patch shape on the abundance of organisms. The effects of patch shape were considered in terms of (1) immigration and emigration of organisms. (2) the amount of available resources in a patch and (3) spatial and temporal heterogeneity of the organisms and environment. I hypothesized that (1) the number of organisms would increase as patch shape elongates because organisms are more likely to encounter an elongated patch, (2) the number of organisms in a patch would remain constant for all patch shapes where the number of organisms in a patch was limited by the amount of resources, because patch shape does not change the patch area that is directly associated with the amount of patch resources, and (3) spatial and temporal variation of the abundance of organisms would increase as patch shape elongates because an elongated patch is more likely to interact with the variable surrounding matrix.Common millipedes,Oxidus gracilis, and their habitat, plywood boards of five shapes (width:length ratio; 11, 14, 19, 136, 1144) with an area of 900 cm² were placed in forest and old field and the number of millipedes appearing under the boards was monitored. Significantly higher mean number of millipedes under the boards was observed at a patch with an elongated shape in the forest and the old field. A significant positive correlation was observed between perimeter length of a patch and the number of millipedes in the old field. The temporal and spatial variation of the number of millipedes was high in the old field. The spatial and temporal variation was higher for boards with elongated shape.     

A case study of forest change in the Swiss lowlands

This paper presents a regional case study of forest development and the history of forest use and management in the north-eastern lowlands of Switzerland during the 19th and 20th centuries. The analysis draws on historical documents related to forestry to consider the following aspects of forest change: forest types, growing stock, trees species composition and non-timber forest uses. Based on the data presented, three overlapping periods of forest use and management can be discerned. The period of traditional multiple use lasted until the second half of the 19th century. From the mid 19th to the mid 20th century, a period of primacy of timber production occurred. During the 20th century, the period of modern multi-impact management has developed. For these three periods, groups of main actors, their needs and interests, and how they were causing the changes in the aspects under study were defined. This procedure of defining periods and the respective groups of main actors is a critical link between landscape ecology and history, as changes in demands of the society can be directly linked with changes in land-use and land-cover.     

Coincidences between different landscape ecological zones and growth forms of Cembran pine (Pinus cembra L.) in subalpine habitats of the Central Alps

The forgotten depots of the European Nutcracker (Nucifraga c. caryocatactes) often lead to the development of tufts of Pinus cembra. In many cases the other individuals of such tufts are not suppressed by the fittest one, rather there is an intraspecific coexistence up to the senescent stage of the trees. There are fusions of separate trunks, and so frequently the individual history of older trees can only be reconstructed by studying sutures, crown structures or trunk cross sections. Different types of trunk fusions are worked out. By means of transect counting the occurrence of these multiple trunk trees is documented quantitatively in different landscape ecological zones of the Engadin region (the Grisons, Switzerland). The data base is 3024 counted microsites of Pinus cembra individuals arising from seeds, including 5272 living individuals. These multiple trunk trees significantly play an important role in the landscape ecological zones of recent glacier recession and at the alpine timberline. Their growth forms have a higher biomechanical stability.     

Pseudoreplication: a sine qua non for regional ecology

We question whether classical experimentation is adequate for real progress in landscape or regional ecology. One cannot do classical experimentation unless one can replicate the treatment. There is conflict between the need to replicate and the need to study processes at appropriately large scales.Because of the difficulties in doing controlled field experiments at regional scales, we propose that landscape ecologists take greater advantage of natural field experiments. Natural experiments must be coordinated, standardized, and synchronized over space and through time, and will require the cooperation of multiple investigators. Distributed computer networks can help provide the automated region-wide monitoring which will supply natural experiments with pre-treatment data.Regions or landscapes need not be replicated, and indeed, cannot be. One can achieve a relational understanding between a system's response and environmental characteristics. This understanding is not definitive, but allows for the development of testable hypotheses, in the classical sense. The confounding of space, time, and/or other environmental factors in pseudoreplicated natural experiments only allows for the development of hypotheses - how-possibly explanations. Discrimination among competing hypotheses can be done at smaller scales and used to infer processes occurring at larger scales. Use of natural and controlled field experiments in complementary roles is a more promising approach than views of one or the other as methodologically inferior.     

Landscape changes and breeding bird assemblages in northwestern Portugal: the role of fire

Fire is a major driving force of landscape change in the Mediterranean region. The objectives of this paper were to explore the implications of landscape change and wildfires in a region of northwestern Portugal for the diversity of breeding birds. Land use cover for the years 1958, 1968, 1983 and 1995 was obtained from aerial photography for a study area of 3700 ha. Breeding bird assemblages in each of six land use categories were characterized in 1998 using point counts. The main landscape changes in the study area across the 40 years were a decrease in the area of agricultural land and low shrublands (respectively 29% and 48%) and an increase in forests and tall shrublands (both over 95%). Bird assemblages showed increased richness and diversity across the gradient: low shrublands tall shrublands conifer mixed deciduous agricultural areas. Many of the species with narrow niche breadth (specialists) were associated with agricultural areas and deciduous forests. In spite of the low diversity of burned areas (mostly shrublands) a few specialist species depend on this habitat. Thus, the current fire regime probably contributes to maintaining bird diversity at the landscape level. There was an inverse relationship between landscape diversity and estimated bird diversity across the last 40 years. Landscape management actions to preserve bird diversity should focus on the maintenance of agricultural land and deciduous forests. In parallel, a wider use of prescribed burning and grazing is suggested. This would contribute to maintaining low shrublands in the landscape, useful both as an habitat for some bird species and as fuel breaks for preventing the occurrence of large wildfires.     

Potential impacts of changing agricultural activities on scenic beauty – a prototypical technique for automated rapid assessment

As a result of the liberalisation of the agricultural market, mountain regions in Central Europe are at great risk of experiencing increasing land abandonment and spontaneous reforestation. Prior to taking measures for landscape maintenance, the ecological and landscape-aesthetic consequences of land abandonment should be analysed. This paper addresses the aesthetic component of such analyses: we investigated whether lay people perceive land abandonment and spontaneous reforestation as a loss or a gain and developed a prototypical technique for rapid aesthetic assessment of reforestation scenarios for vast regions.First, we conducted image experiments to assess the respondents' reactions to increasing levels of reforestation. Based on these experiments we concluded that a medium degree of reforestation is most desirable. Second, we analysed the relationship between scenic beauty and landscape patterns and found that landscape preference values correlate significantly with various quantitative measures of the landscape pattern (e.g., diversity and contagion indices of grey- tone and colour images). Third, we applied a GIS-assisted moving- window technique to transform spatially explicit remote-sensing data (in particular orthophotos) of a test region to spatially explicit data of landscape-pattern indices. Thanks to the significant positive correlation between pattern indices and landscape preference values, the resulting maps can preliminarily be interpreted as beauty-maps of the test-region.     

Gap analysis: concepts,methods, and recent results*

Rapid progress is being made in the conceptual, technical, and organizational requirements for generating synoptic multi-scale views of the earth's surface and its biological content. Using the spatially comprehensive data that are now available, researchers, land managers, and land-use planners can, for the first time, quantitatively place landscape units – from general categories such as Forests or Cold-Deciduous Shrubland Formation to more categories such as Picea glauca-Abies balsamea-Populus spp. Forest Alliance – in their large-area contexts. The National Gap Analysis Program (GAP) has developed the technical and organizational capabilities necessary for the regular production and analysis of such information. This paper provides a brief overview of concepts and methods as well as some recent results from the GAP projects. Clearly, new frameworks for biogeographic information and organizational cooperation are needed if we are to have any hope of documenting the full range of species occurrences and ecological processes in ways meaningful to their management. The GAP experience provides one model for achieving these new frameworks.     

Using fractal analysis to assess how species perceive landscape structure

To develop a species-centered definition of landscapes, I suggest using a fractal analysis of movement patterns to identify the scales at which organisms are interacting with the patch structure of the landscape. Significant differences in the fractal dimensions of movement patterns of two species indicate that the species may be interacting with the patch structure at different scales. Fractal analysis therefore permits comparisons of landscape perceptions of different species within the same environment.I tested the utility of this fractal application by analyzing the movement patterns of three species of acridid grasshoppers (Orthoptera) in a grassland mosaic. The largest species moved up to 6 times faster than the two smaller species, and species exhibited different responses to microlandscape structure within 25-m² plots. Further, the largest species exhibited different responses to microlandscape structure in two pastures subjected to different intensities of cattle grazing. This species thus is able to integrate information on landscape structure at broad spatial scales. Fractal analysis of movement patterns revealed that the two small species had significantly more tortuous patterns than the larger species, which suggests that these species are interacting with patch structure at a finer scale of resolution than the large species. Fractal analysis can be used to identify the perceptive resolution of a species; that is, the spatial grain and extent at which they are able to perceive and respond to heterogeneity. Analysis of movement patterns across a range of spatial scale may reveal shifts in fractal dimension that reflect transitions in how species respond to the patch structure of the landscape at different scales.     

An investigation of uncertainty in field habitat mapping and the implications for detecting land cover change

Land cover data for landscape ecological studies are frequently obtained by field survey. In the United Kingdom, temporally separated field surveys have been used to identify the locations and magnitudes of recent changes in land cover. However, such map data contain errors which may seriously hinder the identification of land cover change and the extent and locations of rare landscape features. This paper investigates the extent of the differences between two sets of maps derived from field surveys within the Northumberland National Park in 1991 and 1992. The method used in each survey was the Phase 1 approach of the Nature Conservancy Council of Great Britain. Differences between maps were greatest for the land cover types with the smallest areas. Overall spatial correspondence between maps was found to be only 44.4%. A maximum of 14.4% of the total area surveyed was found to have undergone genuine land cover change. The remaining discrepancies, equivalent to 41.2% of the total survey area, were attributed primarily to differences of land cover interpretation between surveyors (classification error). Differences in boundary locations (positional error) were also noted, but were found to be a relatively minor source of error. The implications for the detection of land cover change and habitat mapping are discussed.     

Relationships between watershed Stressors and sediment contamination in Chesapeake Bay estuaries

Three methods for assessing the relationships between estuarine sediment contaminant levels and watershed Stressors for 25 Chesapeake Bay sub-estuaries were compared. A geographic information system (GIS) was used to delineate watersheds for each sub-estuary and analyze land use pattern (area and location of developed, herbaceous and forested land) and point source pollution (annual outflow and contaminant loading) using three landscape analysis methods: (1) a watershed approach using the watershed of the estuary containing the sampling station. (2) a partial watershed approach using the area of the watershed within a 10 km radius of the sampling station and (3) a weighted partial watershed approach where Stressors within the partial watershed were weighted by the inverse of their linear distance from the sampling station. Nine sediment metals, 16 sediment organics and seven metals loading variables were each reduced to one principal component for statistical analyses. Relationships between the first principal components for sediment metals and organics concentrations and watershed stressor variables were analyzed using rank correlation and stepwise multiple regression techniques. For both metals and organics, the watershed method yieldedR ² values considerably lower than the partial and weighted partial watershed analysis methods. Regression models using Stressor data generated by the weighted partial watershed landscape analysis method explained 76% and 47% of the variation in the first principal component for sediment metals and organics concentrations, respectively. Results suggest that the area of developed land located in the watershed within 10 km of the sediment sampling station is a major contributing factor in the sediment concentrations of both metals and organics.     

Landscape pattern in topographically complex landscapes: issues and techniques for analysis

Ecological research provides ample evidence that topography can exert a significant influence on the processes shaping broad-scale landscape vegetation patterns. Studies that ignore this influence run the risk of misinterpreting observations and making inappropriate recommendations to the management community. Unfortunately, the standard methods for landscape pattern analysis are not designed to include topography as a pattern-shaping factor. In this paper, we present a set of techniques designed to incorporate the topographic mosaic into analyses of landscape pattern and dynamics. This toolbox includes adjustments to classic landscape indices that account for non-uniform landscape topography, indices that capture associations and directionality in vegetation pattern due to topographic structure, and the application of statistical models to describe relationships between topographic characteristics and vegetation pattern. To illustrate these methods, we draw on examples from our own analysis of landscape pattern dynamics in logged and unlogged forest landscapes in southwestern British Columbia. These examples also serve to illustrate the importance of considering topography in both research and management applications.This revised version was published online in May 2005 with corrections to the Cover Date.     

Changes in anthropogenic impervious surfaces,precipitation and daily streamflow discharge: a historical perspective in a mid-atlantic subwatershed

Aerial photography provides a historical vehicle for determining long-term urban landscape change and, with concurrent daily streamflow and precipitation records, allows the historical relationship of anthropogenic impervious surfaces and streamflow to be explored. Anthropogenic impervious surface area in the upper Accotink Creek subwatershed (near Annandala, Virginia, USA) was mapped from six dates of rectified historical aerial photography ranging from 1949 to 1994. Results show that anthropogenic impervious surface area has grown from approximately 3% in 1949 to 33% in 1994. Coincident to this period, analysis of historical mean daily streamflow shows a statistically significant increase in the streamflow discharge response (per meter of precipitation) associated with normal and extreme daily precipitation levels. Significant changes were also observed in the frequency of daily streamflow discharge at given volumes above and below the historical daily mean. Simultaneously, the historical magnitude, frequency and pattern of precipitation values 0 mm, 6.0 mm and 35.0 mm show either no statistically significant change or influence on streamflow. Historical changes in streamflow in this basin appear to be related to increases in anthropogenic impervious surface cover. Historical aerial photography is a viable tool for revealing long-term landscape and ecosystem relationships, and allows landscape investigations to extend beyond the temporal and spatial constraints of historical satellite remote sensing data.This revised version was published online in May 2005 with corrections to the Cover Date.     

Eintritt für Selbstpflücke, ein Kontinent ohne Frigopflanzen und ‘Elsanta‘

Zusammenfassung Die im Wachstum begriffene australische Erdbeerindustrie ist geprägt durch optimale Klimabedingungen und einfachen Zugang zu den Ressourcen, hohe Intensivierung und — wie in Kalifornien — hohe Erträge über 30 t/ha. Der Markt ist fast autark, Im- und Exporte frischer Erdbeeren spielen keine Rolle. Mit einem derzeitigen Produktionsvolumen von 40.000 t/Jahr auf ca. 1.300 ha wird eine Ausweitung auf 71.000 t bis zum Jahre 2008 angestrebt. Dies entspricht — bei ca. 20 Mio. Einwohnern Australiens — einer Steigerung des Erdbeerkonsums von 2,0 kg auf ca. 2,7 kg/Kopf und Jahr im Jahr 2008. Der gegenwärtige Erdbeerkonsum in Deutschland liegt bereits bei ca. 2,7 kg/Kopf und Jahr, wobei die Erdbeerimporte von ca. 120.000 t die Eigenproduktion von ca. 100.000 t auf 10.420 ha Anbaufläche — im Gegensatz zu Australien — übersteigen. Die drei australischen Hauptanbaugebiete konzentrieren sich auf Queensland im Nordosten, Perth im Westen und Victoria im Südosten Australiens. Der überwiegend einjährige Anbau erfolgt mit 45.000–66.000 Grünpflanzen/ha als Einzel- oder Doppelreihe in Dammkultur und Mulchfolie mit integriertem Fertigationsschlauch. Nach telefonischem Verkauf erfolgt die Lieferung im Kühl-LKW direkt an die Supermärkte oft weit entfernter Großstädte. Als tagneutrale Erdbeersorten dominieren mit 90% amerikanische Sorten wie Selva, Camarosa und Camino Real aus Kalifornien sowie Sweet Charlie und Festival aus Florida. Interessante Neuzüchtungen aus dem Jahre 2003 sind Rubygem, Sugarbaby, Brighteyes und Harmony aus Queensland als Kurztagssorten. Zusammen mit tagneutralen Sorten aus dem südlichen Züchtungsprogramm in Victoria stieg ihr Marktanteil in den letzten drei Jahren von 8% auf 10%. Primäre Zuchtziele des nördlichen Züchtungsprogramms in Queensland sind Kurztagssorten mit frühem Reifebeginn und hohem Ertrag über 1,2 kg/Pflanze. Das südliche Züchtungsprogramm um Victoria zielt dagegen sowohl auf Kurztagssorten als auch Tagneutralität sowie eine zusätzlich lange Ernteperiode über mindestens 10 Wochen. Während die Zuchtziele der äußeren Fruchtqualität wie Fruchtgröße, Fruchtfestigkeit und Glanz mit denen Deutschlands übereinstimmen, unterscheiden sich die der inneren Fruchtqualität wie süßer Geschmack bei gleichzeitiger Säurearmut und hoher Fruchtfleischfestigkeit.     

Bestimmung der S-Allele in Brennkirschensorten (Prunus avium L.)

Zusammenfassung Brennkirschen sind Süßkirschensorten, welche spezielle Eigenschaften für die Branntweinproduktion und die industrielle Verarbeitung besitzen. Ihr Hauptanbaugebiet in Deutschland befindet sich in Baden-Württemberg und in Teilen Bayerns. In den letzten Jahren wurde über einen geringen Fruchtbehang in neu gepflanzten Brennkirschenanlagen berichtet. Süßkirschen sind selbstinkompatibel und benötigen deshalb eine Bestäubersorte. Ursache ist ein gametophytischer Selbstinkompatibilitätsmechanismus, bedingt durch einen S-Lokus. Mit Hilfe molekularer Marker wurden deshalb Untersuchungen zu den S-Allel-Kombinationen in 62 Brennkirschensorten bzw. -herkünften aus dem Raum Oberkirch, Mittelbaden, durchgeführt. Im Ergebnis konnten zwei bisher noch nicht beschriebene S-Allele und 14 neue Inkompatibilitätsgruppen ermittelt werden. Ursache für den schlechten Fruchtansatz in neuen Kirschenanlagen mit den Hauptsorten Dolleseppler und Benjaminer sind die gleichen S-Allel-Kombinationen (S₁S₇) in beiden Sorten. Als mögliche Befruchtersorten werden die Sorten Schwarze Schüttler (S₆S₇), Hartwälder (S₄S₇), Feuerkirsche (S₄S₁₄) und die ehemalige Sorte Dolleseppler der Baumschule Kiefer (S₁S₄) empfohlen.     

Die Zukunft: krankheitsresistente Apfelsorten

Zusammenfassung Integrierte und biologische Anbauverfahren gewinnen zunehmend an Bedeutung. Die Anwendung von Pflanzenschutzmitteln gestaltet sich zunehmend schwieriger bezüglich ihrer Bereitstellung als auch im Hinblick auf zunehmende Umweltsensibilität der Bevölkerung. Im Obstbau ist eine der Alternativen der Anbau resistenter Sorten, die mit weit weniger Pflanzenschutzaufwand produziert werden können. Eines der Ziele der Pillnitzer Obstzüchtung war die Kombination von hoher Fruchtqualität mit guter Ertragsleistung und Resistenz gegenüber Krankheiten und Schädlingen. Resistente früh, mittel und spät reifende Sorten, die Re-Sorten^®, konnten ausgelesen werden. Sie garantieren einen hohen Resistenzgrad unter Feldbedingungen, sie sind aber nicht immun. Dreifachresistente Sorten mit Widerstandsfähigkeit gegenüber Schorf, Mehltau und Feuerbrand sind: Remo, Regia, Rewena und Rebella. Rebella besitzt weiterhin Resistenz gegenüber Rindenbrand, Rote Spinne und abiotische Stressfaktoren. Obwohl in Mitteleuropa seit 1984 verschiedentlich Resistenzdurchbrüche an schorfresistenten Sorten mit M.-floribunda-Resistenz (V_f) beobachtet wurden, blieben die Sorten mit anderer genetischer Basis befallsfrei, so u. a. Reglindis (V_A), Reka (V_r) oder Regia (V_r). Als künftiges Ausgangsmaterial für die Züchtung wurde in der Genbank Obst nach weiteren Resistenzträgern unter den Malusarten und alten Apfelsorten gesucht, das in Zukunft durch Pyramidisierung von Resistenzgenen bei der Züchtung neuer Sorten zu mehr Stabilität unter Feldbedingungen beitragen kann.     

Scale dependence of tree abundance and richness in a tropical rain forest,Malaysia

Abundance and richness are the two fundamental components of speciesdiversity. They represent two distinct types of variables of which the formerisadditive when aggregated across scales while the latter is nonadditive. Thisstudy investigated the changes in the spatial patterns of abundance andrichnessof tree species across multiple scales in a tropical rain forest of Malaysiaandtheir variations in different regions of the study area. The results showedthatfrom fine to coarse scales abundance had a gradual and systematic change inpattern, whereas the change in richness was much less predictable and ahotspot in richness at one scale may become acoldspot at another. The study also demonstrated that differentmeasures of diversity variation (e.g., variance and coefficient of variation)can result in different or even contradictory results which further complicatedthe interpretation of diversity patterns. Because of scale effect the commonlyused measure of species diversity in terms of unit area (e.g.,species/m²) is misleading and of little use in comparing speciesdiversitybetween different ecosystems. Extra care must be taken if management andconservation of species diversity have to be based on information gathered at asingle scale.This revised version was published online in May 2005 with corrections to the Cover Date.