863
FOREST TYPE C l.ASSIFICATION FOR DEGRADATION ASSESSMENT IN
THE MF.NGYANG NATURE RESERVE, P.R. OF CHINA
Robert DE WULF, Roland GOOSSENS and France GERARD,
Laboratory of Remote Sensing and Forest Management, Gent State University
Coupure 653, B-9000 Gent, Belgium
Boudewijn DE ROOVER
Satellite Reimte Sensing Research Programme (TELSAT-II/04)
Coupure 653, B-9000 Gent, Belgium
John MACKINNON
WWF International, World Conservation Centre
CH-1196 Gland, Switzerland
Li ZHI XI
Laboratory of Remote Sensing in Forestry, Southwest Forestry College
Hd: Springs, Kunming, P.R. of China
ABSTRACT
The study area is located in the Xishuangbanna Dai autonomous prefecture
(Yunnan province) in the southwest of the People's Republic of China. The
Mengyang Nature Reserve forms part of the Xishuangbanna Nature Reserve
totalling some 200000 ha.
The variety in relief and soil types, combined with its location in the
subtropical region, yields an exceptional richness of vegetation types,
offering a challenge for a digital image classification exercise. In addition,
human influence profoundly changed the landscape in the past 30 years,
resulting in shifting cultivation and various forms of permanent agriculture
and cash crop plantations.
A Landsat 5 Thematic May.per image forms the basic material for this forest
cover classification case study. Extensive field data collection conducted in
the summer of 1989 served as reference for supervised classification
procedures. The classification exercise involves following experimental
variables: class level, classifier type (layered and single step), structure
of layered classifier and channel selection. The main objective of this study
was to find out if relevant forest classes could be reliably classified. The
distinction between primary forest and secondary forest was examined in detail
in order to evaluate the usefulness of satellite remote sensing for nature
conservation management In an endangered tropical environment.
It was concluded that, combining several classification methods, an accuracy
of 80% for Level III vegetation classes is possible. Secondary forest can be
separated from primary forest (Level II classes) with an accuracy of about 85
%, and Level I classification is possible with an accuracy of 95 %. The best
results are obtained using the mid-infrared and the thermal infrared TM
channels in conjunction with the near-infrared and the red bands.
Key Words : classification, Landsat
nature reserve, China
1. JUSTIFICATION
Mengyang, as well as the jther nature
reserves of Xishuangbanna, features an
exceptional floral and faunal richness,
and is currently the subject of joint
efforts by the Chinese Ministry of
Forestry and the World Wide Fund for
Nature (WWF) to set up a conservation
management plan.
Thematic mapping of the natural and
man-made vegetation types is a primary
requirement for management planning.
Spaceborne remote sensing represents a
convenient and cost-effective technique
to map large areas which a> e difficult
to survey by traditional ground
methods.
The main questions to be answered by
Thematic Mapper, forest degradation,
the exercise described in this paper
are:
1. How well can natural vegetation be
distinguished from agricultural land
use classes.
2. In view of a reliable assessment of
the forest degradation in
Xishuangbanna, is it possible to
distinguish between primary forest
and secondary forest?
3. Which classification strategy yields
the best results. In particular,
what is the contribution of the
Thematic Mapper channels 5, 6 and 7
to the classification accuracy, in
addition to channels 2, 3 and 4.