The use of Landsat TM data to estimate rubber growing area of Thailand
Dr. Suvit Vibulsresth
Dr. Darasri Downreang
Dr. Surachai Ratanas ermpong
Miss. Supapis Polngam
Mrs. Thanomsri Rangsikanbham
Miss Uthaiwan Pornprasertchai
Remote sensing Division, National Research Council
Dr. Likit Nualsri
Dr. Veth Thainukul
Mr. Somyot Sinthurahat
Mr.Udorn Charoensang
Mr.Sutus Danskulphol
Mr. Somjert Phatummin
Rubber Research Institute, Department of Agriculture Bangkok 10900, Thailand
Abstract
A certain part of Nakhon Si Thammarat province, Southern part of Thailand was selected as a test site for the application of simple image processing techniques to identify rubber plantation stages by the use of Landsat Thematic Mapper data. These images were taken during the shedding period of rubber trees.
To produce optimal contrast and variation for color composition, contrast enhancement and histogram equalization techniques were applied to the images with various band combinations. It was found that a combination of band 4, band 5 and band 2 provided the best identification of rubber growing area. This combination was most promising for the separation of rubber plantation from other vegetated area as well as differentiation of rubber of different stages of growth such as young rubber area including nearly cleared area that will be planted with rubber area including nearly cleared nearly cleared area feature and mature rubber area. The results reveal that within the total area of 1,090 sq. km. Under study young rubber plantations with rubber trees 1-4 years of age account for 162. 139 sq. km. While 241.986sq.km. are mature rubber with rubber trees 5-9 years of age, and 162.500 sq. km. are mature rubber with rubber trees more than 10 years of age. The accuracy of classification is more than 80% for rubber plantation area.
Introduction
The study described in this paper is a part of an integrated approach to develop procedure for rubber plantation area estimation particularly for Southern Thailand, Where rubber are mainly planted. From past experiences, multispectral characteristics of rubber plantation and its separability from other cover types, has largely been studied with respect to MSS data. The information in the four MSS bands can essentially represent only two classes, one of which, termed "young rubber area", and the other is mature rubber area (Somyot, 1986)X. In addition, rubber plantation area is subject to confusion with oil palm plantation area.
With the development of higher spatial and spectral resolution satellite data such as Landsat TM the possibility to differentiate various land cover types becomes greater. Therefore, in this paper an attempt is made to explore the potential of TM data as applied to the identification of rubber plantation at different at ages via digital image processing means
- The study area
The study area covers approximately 1, 090 sq.km and is located in Nakhon Si Thammarat province in South Tailand (Figure) It is generally a gently undulation landscape form with limestone feature. The major cultivation are rubber plantation which it is typical for the South, and oil palm plantation located throughout the area.
