Mapping Postfire Vegetation Recovery Using EO-1 Hyperion Imagery

Abstract

The aim of this paper is to investigate whether it is possible to accurately map postfire vegetation recovery on the Mediterranean island of Thasos by employing Earth Observing-1 (EO-1) Hyperion imagery and object-based classification. Specific objectives include the following: 1) locating and mapping areas of forest regeneration and other vegetation recovery and distinguishing among them; 2) distinguishing between <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Pinus brutia</i> regeneration and <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Pinus nigra</i> regeneration within the area of forest regeneration; and 3) examining whether it is possible to distinguish between areas of forest regeneration ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Pinus brutia, Pinus nigra</i> ) and mature forest. The data used in this study consist of satellite images, field-spectroradiometry measurements, and field observations of the homogenous revegetated areas. The methodology comprised four consecutive steps. The first step involved preprocessing of the Hyperion image and field data. Subsequently, an object-oriented model was developed, which involved three steps, namely, image segmentation, object training, and object classification. The process resulted in the separation of five classes (¿ <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">brutia</i> mature,¿ ¿ <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">nigra</i> mature,¿ ¿ <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">brutia</i> regeneration,¿ ¿ <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">nigra</i> regeneration,¿ and ¿other vegetation¿). The accuracy assessment revealed very promising results (approximately 75.81% overall accuracy, with a Kappa Index of Agreement of 0.689). Some classification confusion involving the classes of <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Pinus brutia</i> regeneration and <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Pinus nigra</i> regeneration was recorded. This could be attributed to the absence of large homogenous areas of regenerated pine trees. The main conclusion drawn in this paper was that object-based classification can be used to accurately map postfire vegetation recovery using EO-1 Hyperion imagery.