Forests and landslides


RAP PUBLICATION 2011/19

Forests and landslides

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Food and Agriculture Organization of the United Nations
Regional Office for Asia and the Pacific
Bangkok 2011


ABSTRACT

Steep terrain, vulnerable soils, heavy rainfall and earthquake activity make large parts of Asia highly susceptible to landslides. The significance of landslides is set to increase in the coming years as a result of population growth, expansion of infrastructure, and increased forestry and agricultural activity in the region. In temperate and tropical Asia, projected climate change related impacts are likely to result in compound effects of landslide incidences. Landslides cause environmental damage to forests and agricultural resources by removing topsoil, blocking rivers and increasing downstream sedimentation. Scientific studies confirm the crucial role of trees and forests in preventing landslides not only by reinforcing and drying soils, but also in directly obstructing smaller slides and rock falls. However, the role of trees and forests in the case of deep-seated landslides or in extreme events is unlikely to have any effect. Landslides are a growing hazard in Asia and it is important for policy-makers to understand when, where and how trees and forests are useful in reducing landslides, and what they can and cannot do, based on sound science. This publication describes, from a technical standpoint, the extent to which the preservation or planting of forests can reduce the incidence of landslides, and where forestation projects are valuable in land rehabilitation and stabilization after landslides occur. Key findings and recommendations for policy-makers are provided, as well as an extensive list of reference materials.



Table of Contents

Acknowledgements
Foreword
Abstract
Background
    Forests and landslide prevention links
    Forests and landslide rehabilitation links
    Landslide trends in Asia
    Climate change links
    Protection forests extent and status
Why landslides are a growing hazard
    Changing rainfall and snowmelt patterns
    Earthquakes and seismic activity
    Road and railway construction
    Deforestation and land use conversion
Climate, landslides and the role of forests
    Relevant landslide types
    Topography, geology and climate
    Role of forests and trees in prevention
    Evidence of landslide prevention
Implications of climate change
    North Asia
    Tibetan plateau
    East Asia
    South Asia
    Southeast Asia
Towards effective management of landslide risk
    Protection of landslide-prone landscapes
    Slope protection and reclamation of landslides
    Identification and monitoring of landslide hazards
Conclusions
Recommendations
References




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ISBN 978-92-5-106994-3


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For copies write to:Patrick Durst
Senior Forestry Officer
FAO Regional Office for Asia and the Pacific
Maliwan Mansion, 39 Phra Atit Road
Bangkok 10200, Thailand
Tel: (+66) 2 697 4000
Fax: (+66) 2 697 4445
E-mail: RAP-Publications@fao.org

© FAO 2011