Contribution of Topographically Explicit Descriptors of Landscape Measures for Application in the Vector Data Environment

Jomaa Ihab,Auda Yves

doi:10.4236/jgis.2010.23023

Abstract

Digital terrain models (DTMs) are not commonly used to integrate for landscape spatial analysis. Two dimensional patchcorridormatrix models are prototypes in landscape spatial ecology analysis. Previous studies have motivated ecologists to integrate terrain models in landscape analysis through 1) adjusting areas and distance calculations prior computing landscape indices; 2) designing new indices to capture topography and 3) searching the possible relationship between topographic characteristics and vegetation patterns. This study presents new indices called Relative number of Topographic Faces (RTF) and Simplicity of topographic Faces (STF) that can be easily computed in a GIS environment, capturing topographical features of landscapes. Digital terrain model was first prepared and topographic units were extracted and installed in computing the suggested indices. Mountainous and rugged topography in Lebanon was chosen on a forested landscape for the purpose of this study. The indices were useful in monitoring changes of topographic features on patch and landscape level. Both indices are ecologically useful if integrated in landscape pattern analysis, especially in areas of rugged terrains.

Highlights

Ecological concern was about quantifying patterns in the spatial heterogeneity of landscapes [1]
This study presents new indices called Relative number of Topographic Faces (RTF) and Simplicity of topographic Faces (STF) that can be computed in a GIS environment, capturing topographical features of landscapes
A topographic face could remain in the possible smallest subdivision generated through Triangulated Irregular Network (TIN) computation or generalization of faces could be practiced depending on the study purpose

Summary

Introduction

Ecological concern was about quantifying patterns in the spatial heterogeneity of landscapes [1]. Neutral landscapes remain the backbone of landscape pattern analysis, especially when two dimensional patch-corridor-matrix models are integrated into friendly and easy to use packages of landscape analysis. Ecologists know well the effect of topography on patterns and processes, trials are still rare to integrate topographical characteristics in a landscape spatial analytical approach. Previous proposals on introducing topography to landscape indices include 1) correcting surface areas and distances prior to landscape metric computation, 2) designing new indices that could relate vegetation pattern with topographical characteristics, and. Surface metrics are to be used for continuous representation of spatial heterogeneity but unlike patch metrics they are less accessible for direct computation to the hand of landscape ecologists. A simple easy to use topography related indices remains as a priority

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Conclusion