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Forest degradation, a methodological approach usingremote sensing techniques: literature review

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par Jean-fiston Mikwa
Ghent University - Master 2011

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Physical Land Resources


Ghent University

Free University of Brussels


Forest degradation, a methodological approach using remote sensing techniques: Literature Review

Jean-fiston MIKWA

Promotor: Prof. Dr. Rudi Goossens

Academic Year 2010 - 2011


Table of contents

0. Introduction 1

1. Remote Sensing, an Overview 2

1.1. Definitions 2

1.1.1. Analog remote sensing 2

1.1.2. Digital Remote Sensing 2

1.2. Digital image analysis 5

1.2.1. Image Acquisition/Selection 5

1.2.2. Pre-processing 5

1.2.3. Classification 5 Combined Approaches. 6 Advanced Approaches. 6 Object-Based Approaches ( polygon approach) 6

1.2.4. Post-processing 7

1.2.5. Accuracy Assessment 7

1.3. Digital Image Types 7

1.3.1. Multispectral Imagery 7

1.3.2. Hyperspectral Imagery 8

1.3.3. Digital Camera Imagery 8

1.3.4. Other Imagery 8

2. Forest Degradation 8

2.1. Key concepts to forest degradation 8

2.2. Main causes of forest degradation 9

3. Mapping forest degradation 10

3.1. Remote sensing in forest degradation 10

3.2. Forest change detection analysis 11

3.4. Indirect methods of forest degradation mapping 13

3.5. Relevancy of different forest degradation approach 14

3.6. The use of vegetation indices as NDVI concept to assess forest degradation 15

3.7. Forest canopy change and remote sensing 16

3.8. Comparing Forest Inventory and Remote Sensing Measurement for forest degradation

mapping 17

3.9. Estimating Forest Volume Using Remote Sensing 17

3.10. Estimating forest biomass using remote sensing 18

3.11. Estimating Forest Carbon Stocks from Remotely Sensed Data 18

4. Conclusion 19

5. References 20


0. Introduction

Forest degradation is a serious problem, environmentally, socially and economically particularly in developing countries. It is estimated that as much as 850 million hectares (ITTO, 2002) of forests and forest lands are degraded. Yet it is difficult to quantify the scale of the problem since at national and sub-national levels forest degradation is perceived differently by the various stakeholders who have different objectives.

Forest degradation has adverse impacts on forest ecosystems and on the goods and services they provide. Many of these goods and services are linked to human well-being and some to the global carbon cycle and thus to life on Earth.

Policy makers and forest managers need information on forest degradation. They need to be able to monitor changes happening in forests. They need to know where forest degradation is taking place, what causes it and how serious the impacts are in order to prioritize the allocation of scarce human and financial resources to the prevention of degradation and to the restoration and rehabilitation of degraded forests. (Simula , 2009).

In addition, reviewing on forest degradation is required to demonstrate efforts to tackle the problem and meet global objectives and targets. The proposed new Biodiversity Target includes a target on reduction of forest degradation. The agreement to establish a mechanism under the UNFCCC aimed at reducing emissions from deforestation and forest degradation (REDD) in developing countries has added a political dimension and the potential availability of substantial funds to reward developing countries that manage to reduce the level of forest degradation.

Accurate and up-to-date land use/cover assessments are important to define natural resource management strategies and policies for conservation especially in forest areas. Understanding the causes and consequences of land cover change and their cascading effects on many components of functional ecosystems, are the case for identifying negative effects on biological resources and human development ( Bicheron et al,2008; Bunker et al, 2005).

Satellite remote sensing provides a meaningful method for detecting vegetation or land cover changes (Smith et al, 2004). Changes in the composition and spatial distribution of forest cover are a major environmental concern, affecting many biological, biochemical and ecological processes. Remotely sensed data are widely used to understand and manage environmental resources by determining land cover/use changes such as quantification of forest degradation. By comparing the images taken in different times, the changes in landscape level can be easily detected. Monitoring land cover and land cover change at regional and global scales often requires sensors data to identify and map landscape features and patterns with sufficient detail (


Defries et al., 2001).Detailed and updated resource inventories are needed to support land use planning and sustainable management .

This literature review addresses how remote sensing techniques can be used to assess forest degradation directly or indirectly by mean of different type of degradation process occurring in the forest area.

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