Landscape structure: identification and assessment
Ján Oťaheľ, Ján Feranec
Institute of Geography, Slovak Academy of Sciences, Štefánikova 49, 814 73 Bratislava, Slovak Republic
Introduction
Landscape structure is a result of natural composition of known geo-elements (Zonneveld, 1988) and their properties that interact with each other. At the same time, it is the result of human influence on landscape. It means also that its cognition is suitable and helpful at least at two levels, i.e. natural and humanised level, namely for the study of the key interactions. Natural landscape structure can often be analysed only as an abstract layer of real landscape, necessary above all for the analysis of causality and for the cognition of the self-regulating mechanism. For the identification of natural landscape types synergic vertical and horizontal relations of the interacting components and their key properties are analysed. Spatial expression of natural landscape types presents hypothesis of possible landscape (land) with regard to its geoecological (abiotical) conditions. In fact this hypothetical landscape is used by man (society) in various ways and intensity. The contemporary (humanised) face of the landscape is spatially diferentiated by the physiognomic, visual atributes.
A suitable tool of identification of the real landscape structure is represented by the remote sensing data recording the reality precisely by following the visual traits. The contemporary landscape structure is rendered by the land cover categories, i.e. spatial objects of the Earth surface characterised by morphostructural and physiognomic attributes. Land cover and its interrelation to the natural landscape basis is a salient point for an integration of the material and physiognomic attributes of landscape. Its spatial differentiation is close to the structure denoted by Forman and Godron (1986) as landscape elements, or ecosystems.
Efficient study of the relation nature-man requires the differentiated analysis of both landscape layers: the natural and humanised. Differentiated analysis of natural (natural landscape types) and contemporary landscape (land cover) aims at the evaluation of their interrelation in the context of vertical and horizontal correctness and solution of ecostabilizing functions, according to the hierarchy and connectivity of the ecological network (ecological importance of landscape). Even simple comparison of the mentioned layers allows analysis of adequacy of land cover/land use as related
to their natural assets and makes primary assessment of vertical and horizontal correctness feasible. This comparison shows limits and reserves of land use with regard to natural conditions (Richling et al. 1996: Oťaheľ and Feranec, 1997). The real state of landscape, identified and presented by land cover, is a base of landscape pattern assessment. Examples of the identification and assessment of landscape structure are presented in the case studies at the local and regional studies.
Landscape structure identification: data and methods
The identification of the natural landscape structure poses exact reconstruction of landscape before man’s input. It is aimed at the key properties, decisive in the mechanism of self-regulative processes and natural landscape regime. The knowledge of the key properties is more important especially from the aspect of men activities application. An analysis of the potential natural vegetation (for instance J. Michalko et al. 1986) is methodologically similar to the reconstruction of landscape. Spatial taxonomy, i.e. presentation of the key properties of the natural landscape according to the spatial units, and relatively homogeneous attributes is used. For identification of natural landscape types synergic vertical and horizontal relations of the single components (especially substrate, relief, soils, potential vegetation) and their key properties are analysed, and in their spatial expression overlay technique is applied. It is methodologically based on the geoecological research (analysis of geocomplex) for instance by Mazúr et al. (1980), Richling et al. (1996) or on regional level those by Oťaheľ and Poláčik (1987).
An adequate salient point of the contemporary landscape structure cognition is identification of land cover, objects of bio-physical essence. Land cover represents a materialized projection of the natural spatial assets (morphopositional and bioenergetic) and contemporary land use, i.e. by man (society) recreated (cultivated) or created (artificial) landscape objects, at the same time.
Land cover at regional scale was identified following the CORINE land cover methodology by visual interpretation of the satellite images of LANDSAT and SPOT PAN at scale 1:50 000 (Heymann et al. 1994, Feranec et al., 1996). Classification scheme of the CORINE land cover classes was itemised at the 4th level following the works of Feranec and Oťaheľ (1995, 1999) and Feranec et al. (1997), and respecting the methodological principles (with the smallest mapping area of 4 ha). Aerial B&W photographs at scale 1:30 000, topographical maps at scale 1:50 000 and 1:10 000, thematic maps of the main timber species, nature protection areas and field research were the main supported data.
Identification of the land cover at local scale was carried out by visual interpretation of the colour infrared photographs based on the methodology of the BIOTOPES and LAND COVER CORINE projects (see Oťaheľ and Feranec, 1993).
Photographs were taken from a helicopter on KODAK 2443 Ectachrome infrared film and arranged into a photomosaic positionally corresponding with the topographic map at a scale 1 : 10 000. Land cover map at the scale 1 : 10 000 brings closer the character
of land cover by compatible physiognomic-ecological formations after the methodology of the BIOTOPES project in the context of habitat types.
Landscape assessment
Landscape structure assessment – ecological aspect
Land cover types in regional scale are close to the basic categories of the land use. Visual attributes of urban and agricultural landscape corresponds with its basic functions and indicate the spatial organisation of cultural landscape. Analysis of functions is, however, indispensable mainly in the categories of forest and semi-natural landscape emphasising the hierarchy of ecologically significant areas.
Functioning of the real landscape becomes easily legible through analysis of its mechanisms. In vertical dimensions it is focused on synergic relations of the self- regulative properties and mutual comparison of differentiated structures. Geometrically and positionally correct maps (schemes) of land cover and natural landscape types are an adequate tool for the analysis of vertical relations (Oťaheľ and Feranec, 1997).
Direct superimposition of both maps make possible to analyse the mutual correlation (diversity) of single land cover classes with relatively homogeneous types of natural landscape. Comparison is aimed at the key synergic relations as ensuing from the regime of natural landscape and functional mechanism of human activities. The aim of the comparison is optimising the quoted relations and reduction of possible environmental risks. The relation land cover/land use to the natural base (see Fig. 1 and 2) in case study of part of Liptov (Oťaheľ and Feranec, in presss) is determined by georelief, namely position and inclination properties. For instance location of settlements at the valley bottoms in the basin is determined by their relation to surface streams and ground water sources existing in floodplains and river terraces. Arable land and grasslands strongly correlate with the relief inclinations.
Analysis of horizontal relationships in landscape is oriented to the study of an optimum landscape structure in the context of its eco-stabilising functions. It is based on correct spatial knowledge of the existing state of land cover. Land cover with its synergic vertical relation to the natural base and its inner composition (heterogeneity of bio-physical matter) points at the potential rate of self-regulative and self-regenerating capacities or at the rate of social regulation necessary landscape for functioning.
Land cover classes composition is analysed by ecological significance of vegetation formations (originality, uniqueness, diversity, function) and their spatial properties (shape, size, neighbourhood). To be able to estimate and control the horizontal spatial relations within the rational spatial organization and eco-stabilising functions, the pattern analysis of land cover categories have to be accompanied by an analysis of functional priorities in a given space. Analysis is connected with search of a natural network of biotic landscape elements which is supplemented by knowing the landscape phenomena, unique from the viewpoint of social interests (water and forest management, nature protection). Above all they are the nature protection areas with different management ensuing from legislation in force. Analysed land cover areas and landscape phenomena represent the skeleton bodies (corres) of ecological network.
Functionality of ecological network is provided for by interacting line or belt elements of land cover (biocorridors).
Analysing horizontal relations within landscape we respect also the natural property of live organisms, the movement (Forman and Godron, 1986). We are particularly interested in the locomotion of the terrestrial animals, which represent the natural flows in landscape. In our analysis it is the search of their natural linkages (conduits) over the land cover structure. We start from positive landscape elements differentiation hierarchised by ecological significance and negative elements in the sense of their environmental impact. In case study we simplify the analysis by migration of higher wild animals between the supraregional wholes in N-S direction (see Fig. 3).
Ecological significance, porosity and hospitality of positive elements, but also intensity and number of barriers and limits of negative elements are estimated while looking for natural linkages with the relatively smallest resistance.
The search for connectivity across the biggest barriers which in our area are represented by the highway, first class roads and the railways is also important.
While proposing the connection, we also analysed natural corridors of water streams which cross the barriers by bridges of various size. A buffer zones, especially in the local solution, are proposed for the negative and risk elements with strong impact on environment. Functioning of flows in proposed conduits should improve care of the critical spots in landscape. The proposed analysis of horizontal relations is a source material of environmental projection and a material characterising ecological network status and functionality.
Landscape pattern assessment – aesthetical aspect
Land cover or habitat types at local scale present a suitable source for the analysis of landscape pattern also from their aesthetics point of view . It results from a substance of land cover. Land cover presents objects of bio-physical substances differentiated on the Earth surface, particularly above all by their appearance and morpho-structural properties. These properties are prerequisite of a close-to-reality interpretation (perception process) of land cover from aerial photographs and satellite images.
For the assessment of spatial attractiveness we chose the flood plain of the Morava River as a part of Nature Park of Záhorie. An apparently monotonous fluvial plain is differentiated by natural vegetation formations like the rest of the original alluvial forests, trees and shrubs (soliteries and lines). Floodplain surface (cover with wet and mesophile meadows) is differentiated also by the depressions left here by the branches of the Morava River, and dead branches with open water tables (with aquatic vegetation: Nuphar lutea) and wetland vegetation species (tall and small reed beds).
The mentioned land cover types (Oťaheľ, 1999) and natural phenomena of the Morava floodplain are interesting also from their aesthetics and scenery point of view. Spatial differentiation of the land cover types and their morphostructural and physiognomic traits enable to evaluate their spatial diversity in the sense of aesthetic qualities. While selecting the assessment factors, we were inspired by the work of Snacken, Antrop (1983).
We used a regular network of squares of 100 m long sides, the overall area of assessment was 1 ha. The criteria of assessment were represented by the following attributes: landscape diversity (number of land cover types - landscape elements), landscape complexity (number of elements - areas), length of edges of the forest and tree lines, length of the edges of water areas and water streams, attractiveness - aesthetic quality of land cover types, colourfulness of the types (maximum number of colours in type over the year) and vertical diversity of the types (height). Every attribute can be differentiated within the spatial units after the qualitative or quantitative traits (variables). Measuring of the variables was at the level of multi-preferences or multi-criterial evaluation. For the sake of precision it was necessary to determine the significance (order of importance) of single attributes. Order of importance of the attributes was assessed with mutual comparison of all pairs technique. Number of preferences of each attribute determined the order of its importance. In order to apply additiveness in the process of multicriterial evaluation we used the standards (Oťaheľ, 1999).
Sum of the values (preferences) of each attribute in corresponding unit was multiplied by the standard co-efficient of its importance – standard weight. Multi- preference of each spatial unit is the sum of values (preferences) of each attribute.
Resulting values were classified to 5 regular intervals, representing 5 degrees of attractiveness of the evaluated units, from relatively least attractive to the most attractive spatial unit (Fig. 4).
Vistas in the study area were evaluated looking of the cyclo-tourist track as observation points of a visitor. In visitor’s vista the land cover objects their third vertical dimension (height), factor of screening off by the forest line trees and partially shrub and reed formations or groups of trees, and shrubs are decisive. The quoted screening off coulisses delimit the visible section of landscape - limited angle of vision (vista section) and distance (depth) of visibility. Quality of the vistas is refreshed by the composition of landscape elements, quality of the local scenery, evaluated as the attractiveness of the area (see Oťaheľ, 1999).
Conclusion
Identification of landscape structure in the sense of differentiated layers (the hypothetical natural landscape types and the real land cover types), with the cognition of natural regime and laws opened the opportunity to assess their relation in the contemporary landscape. Direct comparison of both layers of landscape structure pointed at the corectness of vertical and horizontal relations (and diversity) in context of respecting the ecological and environmental principles by man/society. This comparison makes also possible to assess the landscape diversity and eco-stabilising functions of real landscape. The assessment of landscape pattern according to its positive and negative elements presents the ecological network, possibilities of natural connections (conduits) of animals with regard of porosity and hospitality of landscape. The landscape pattern assessment following the principles of attractivenes and aesthetics determines the qualities of territory for tourism and recreational activities. The quoted assessments
are presented as the basis for the decision making in environmental planning.
Acknowledgements
The authors wish to express their gratitude to the grant agency VEGA for their support, in part under grant 5043: “Contemporary landscape evaluation by application of the CORINE land cover databases in the sense of environmental principles”.
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Fig. 1. Natural landscape types
Legend
1 Cool basin accumulated-eroded landscape
11 Floodplains with alder submontane and montane floodplain forests on fluvisols 111 Wide gravel floodplains up to low terraces with high bearing of porous ground water
112 Narrow loamy floodplains with low bearing of ground water 12 Proluvial-fluvial hilly lands
121 Moderately undulated hilly lands
1211 Terraces and cones with medium bearing of ground water and oak- linden-
spruce forests on luvisols and cambisols
1212 Travertine hills with subxerophilous vegetation on rendzinas
1213 Hilly lands on flyschoid rocks with oak-linden-spruce forests on cambisols 12131 Remnants of denudation plateaus
12132 Gently inclined slopes
1214 Hilly lands on carbonatic substratum with pine-spruce forests on rendzinas 122 Moderately cut hilly lands
1221 Remnants of terraces with oak-linden-spruce forests on cambisols 1222 Travertine hills with subxerophilous vegetation on rendzinas
1223 Hilly lands on flyschoid rocks with oak-linden-spruce forests on cambisols 12231 Remnants of denudation plateaus
12232 Medium steep slopes with slides
1224 Hilly lands on carbonatic substratum with pine-spruce forests on rendzinas 13 Polygenetic subberglands
131 Remnants of terraces with oak-linden-spruce forests on cambisols 132 Travertine hills with subxerophilous vegetation on rendzinas
133 Subberglands on flyschoid rocks with oak-linden-spruce forests on cambisols 1331 Remnants of denudation plateaus
1332 Steep slopes with a predominance of slides
134 Subberglands on carbonatic substratum with pine-spruce forests on rendzinas 2 Montane eroded-denuded landscape
21 Cold highlands and high plateaus on carbonatic substratum with rocky steppe and fir-beech forests on rendzinas
211 Remnants of denudated plateaus 212 Very steep slopes
213 Narrov gravel floodplains with montane floodplain forests
22 Cold mountains on carbonatic substratum with spruce forest on rendzinas 221 Remnants of denudated plateaus
222 Very steep slopes
23 Very cold high mountains on carbonatic substratum with dwarf pine and alpine
Fig. 2. Land cover
Legend
1 Artificial surfaces
1122 Discontinuous built-up areas with family houses with gardens 1211 Industrial and comercial units
1212 Areas of special instalations 1221 Road network and associated land 1222 Rail network and associated land 1242 Airports with grass surfaces of runways 1311 Open cast mines
1411 Parks 1412 Cemeteries 1422 Leisure areas 2 Agricultural areas
2111 Arable land prevailingly without dispersed (line and point) vegetation 2112 Arable land with scattered (line and point) vegetation
2221 Orchards
2311 Pastures prevailingly without trees and shrubs 2312 Pastures with trees and shrubs
2421 Complex cultivation patterns without scattered houses
2431 Agricultural areas with significant share of natural vegetation, and with prevalence of arable land
2432 Agricultural areas with significant share of natural vegetation, and with prevalence of grasslands
2433 Agricultural areas with significant share of natural vegetation, and with prevalence of scatered vegetation
3 Forest and semi-natural areas
3111 Broad-leaved forest with continuous canopy 3113 Broad-leaved forest with discontinuous canopy 3121 Coniferous forest with continuous canopy 3122 Coniferous forest with discontinuous canopy
3131 Mixed forest created by alternation of single trees with continuous canopy 3132 Mixed forest created by alternation of stands of trees with continuous canopy 3211 Natural grasslands prevailingly without trees and shrubs
3212 Natural grasslands with trees and shrubs 3241 Young stands after cutting (and/or clear cuts) 3242 Natural young stands
3332 Sparse vegetation on rocks 4 Wetlands
5 Water bodies 5111 Rivers
5122 Artificial reservoirs
Fig. 3. Ecological significance of landscape (regional approach)
Legend
1 Areas with a distinct prevalence of natural and semi-natural vegetation 11 Areas of supraregional significance
Bioareas (biocenters) with a prevalence of vegetation formations only little or not changed, with a very high ecological stability 111 Large forest complexes
112 National parks 113 Nature reserves
12 Areas of regional to local significance
Bioareas with a prevalence of a little changed and medium modified vegetation formations, with a high ecological stability
121 Forest complexes 122 Protected areas
123 Grasslands with trees and shrubs
2 Areas with a prevalence of medium and strongly modified vegetation Land cover/land use elements with a prevalence of medium
and strongly modified vegetation and medium environmental impact 21 Grassland
22 Agricultural (prevailingly arable) land 23 Orchards
24 Parks, cemeteries, leisure areas
25 Built-up areas (family houses with gardens) 26 Water courses
27 Artificial water reservoirs
3 Areas with a prevalence of artificial elements Land cover (negative and risky) elements with heavy environmental impact
31 Highways with associated areas 32 Main roads with associated areas 33 Railways with associated areas 34 Airports
35 Industrial areas 36 Agricultural farms 37 Mineral extraction sites
4 Proposal of ecological connectivity improvement 41 Linkages (conduits) of supraregional significance 42 Linkages (conduits) of regional to local significance 43 Improvement of connectivity
Improvement of negative and risky elements buffering
Legend:
I: Attractiveness of the spatial units: 1 the least attractive, 2 little, 3 medium, 4 very, 5 the most attractive;
II: Categories of vista sections: 1: elementary (vision angle of 30-56o), 2: sectorial (60-115o), 3: panoramic (120-240o), 4: circoramic (250-360o);
III: Distance zones of visibility: 1 close vista (limited by the coulisse of trees to 500 m), 2 half-open vista (partially limited by the tree coulisse up to 2 km), 3 open vista (visibility of background over 10 km).
Fig. 4. Attractiveness of the study area and qualities of the vistas.
