Evaluation of Landscape Metrics on Forest Fragmentation – Analysis based on Modeled Observations - Petropolis, Rio de Janeiro, Brazil.
ISBN 978-85-88783-11-9
Authors
1Santos Miceli, B.; 2do Couto Fernandes, M.; 3Temponi de Oliveira, L.M.
1UNIVERSIDADE FEDERAL DO RIO DE JANEIRO Email: bruna.s.miceli@gmail.com
2UNIVERSIDADE FEDERAL DO RIO DE JANEIRO Email: mfernandes@ufrj.br
3INSTITUTO BRASILEIRO DE GEOGRAFIA E ESTATÍSTICA Email: lutemponi@gmail.com
Abstract
Forest ecosystems in Brazil have suffered with the progressive intensification of human action, which led to the continuous growth of forest fragmentation. The main objective of the present work is to understand the forest fragmentation processes within the Environmental Protection Area (APA) of Petropolis, RJ – by analysing the horizontal structure of forest fragments through the use of landscape metrics, comparing the results on planimetric and modeled (3-D) surface observations. The methodology takes into account the roughness of the landscape in order to achieve results closer to reality, especially considering the rugged topography of the study area. The methods employed uses land cover maps as an input for the delimitation of forest fragments, which are examined from a temporal perspective, within a period of 13 years (1994 and 2007) on a scale of 1:100.000. In addition, a comparison between the fragmentation results and the entire geomorphological configuration of the Environmental Protection Area of Petrópolis was made so as to compare the landform configuration within both surface observations. The adopted methods showed consistent results and may be used in others studies concerning forest fragmentation. The main results showed the variations between the observations in planimetric and modeled surface became clear in all metrics differences, on different time. The circularity index showed that fragments in modeled surface are less ring-shaped than in planimetric surface, ie, when evaluated modeled shaped surface forest fragments are often more susceptible to degradation when taken into account the circularity index. Regarding landform classification, it was found that the fragments are concentrated, especially in the headwaters and mountain tops, which justifies the application of analysis based on observations of modeled surface, particularly in this type of rough landscape. This study suggests that planimetric and modeled (3-D) surface observations allows different interpretations concerning the conservation status of forest fragments. Therefore, both methods have advantages and should be employed in forest fragmentation studies.
Keywords
Forestry Fragmentation; Digital Elevation Models; Geoecology