The Ecosystem Classification And Gis Demonstration For Sandakan

By Flemming T. Hansen

GIS Specialist

Introduction

This paper presents the ecosystem classification and demonstrates the use of GIS using the following examples:

• Examples of digital maps of Sandakan district
• Examples of GIS analyses of a few issues related to the Sandakan Coastal Zone Profile.

• Mapping of natural habitats in Sandakan district.

Digital maps of Sandakan district

Digital computer maps are equivalent to traditional paper maps. Digital maps are produced using a GIS software by which it is possible to perform both simple and more advanced analyses in a minimum of time.

Fig.1: Landform map of Sandakan District presented in ArcView GIS. Each colour represents a unique landform class described in the colour legend to the left

A number of maps have been produced and presented in the Sandakan Coastal Zone Profile. A few examples were given to show the maps using the GIS software, ArcView. These examples included:

• Sandakan districts boundary including roads and rivers (Department of Forestry)
• Landforms (Department of Agriculture - KK)
• Soil suitability (Department of Agriculture - KK)
• Land use (Department of Agriculture - KK)
• Population density (Statistical Department - KL)
• Local Plan 1990
• Sandakan Town and Environmental Scheme
• Seguntor Scheme

GIS-analyses

GIS is a very powerful tool for integrated planning. If the appropriate digital maps are available it is possible to do rapid analyses identifying areas susceptible to soil erosion or soil degradation, areas contributing significantly to siltation of rivers, areas most suitable for rural development with a minimum of environmental impact etc. In a planning situation it is possible to consider an unlimited number of issues and get an overview of benefits and concerns.

A few examples were given to give an idea on the capabilities a GIS software provides:

• Identification of ‘overused land’. Overused land is defined as areas registered as agricultural land use (land use data from Department of Agriculture) but regarded as unsuitable for agricultural purpose (soil data from Department of Agriculture).
• Identification of areas suitable for agricultural development. Areas classified as suitable for agricultural purpose (soil data from department of agriculture) with a population density between 50 and 200 individuals pr. km ² (data from statistical department). The population density interval was picked assuming that these areas provide a sufficient social and physical infrastructure for rural development.
• A simple ‘integrated’ planning approach. Considering the distribution of existing forest lands (land use data from Department of Agriculture) and the distribution of an ecologically important key species (a fictive orang-utan distribution map) when planning the rural development in Sandakan district.
• Identifying erosion susceptible areas. Erosion susceptible areas are in this example defined as areas with agricultural land use (land use data from department of agriculture) on landforms with moderate to steep slopes (soil data from Department of Agriculture).
• Determining the population size within a 5-km distance of a major road. Using GIS functionality (buffer) to determine the total Sandakan population (data from Statistical Department) within a 5-km distance to all major roads in Sandakan District. This type of analysis is very useful when evaluating existing and future infrastructure in a region.

Fig.2: Areas identified as erosion susceptible areas due to agricultural exploitation in Sandakan District.

Fig.3: Population density in a 5 km distance to all major roads in Sandakan District. Population density is grouped into 5 classes described in the legend to the left.

Natural habitats

As part of the ICZM Task Force 4 presented in the Sabah Coastal Zone Profile report (September 1998) a classification system for the natural habitats of Sabah Coastal Zone was proposed. This classification system is based on an existing and proven Wetland classification developed by the US Fish and Wildlife Service.

Table 1: Major classes of the habitat classification system of Sabah Coastal Zone.

The Department of Forestry has initiated the work of producing a habitat map covering Sandakan District. The recent work has focused on how to ‘fit’ the existing data available for Sandakan District into the proposed habitat classification system. The work has been concentrating on data from the Department of Forestry and the Department of Agriculture, and thus primarily on the terrestrial and some of the semi-terrestrial habitats. A complete habitat map will rely on data from other departments that may contribute with data describing each of major classes shown in Table 1.

The data available from Departments of Agriculture and Forestry falls into the following major classes:

Preliminary conclusions

1. 1) The mangrove classification from Department of Forestry comprises a number of mangrove vegetation classes. In the above table there has been no distinguishing between forested wetlands and scrub wetlands. However the various vegetation classes may be divided into two classes based on average or maximum height. Using a general or suitable definition on the difference between scrub and forests, such classification would be advisable.

1. The Mangrove classification from Department of Forestry covers a large area of Sandakan District and most of Sabah State. However, areas that are not within the jurisdiction of the Forestry Department are lacking. The Land Use classification from Department of Agriculture includes “Marshland and swamps” which can be used as a supplement to the mangrove classification. To be able to distinguish between the 3 different wetland classes in the Estuarine system, land use data need updating by for example using aerial photographs.

1. The landforms ‘Floodplains’ and ‘Peat swamps’ from the Landform classification (Department of Agriculture) may be representative of the Palustrine habitats. However, there is a need to look into the definition of these classes and perhaps compare them with other information including land use data, aerial photographs and/or drainage and irrigation data.

1. The terrestrial system only consists of one habitat class within the coastal zone of Sabah, the lowland forest. Only a minor area of Sandakan District and also of the whole coastal zone of Sabah falls within the jurisdiction of the Department of Forestry. Thus the information on forested land from this department are limited. The land use classification from Department of Agriculture includes ‘Forested land’ and covers a large part of the coastal zone of Sabah and Sandakan district and is the best data at present describing the distribution of forested areas.

1. In general one aspect that is of major ecological relevance when it comes to describing habitats is their condition or shape. For forested land or for instance coral reefs there is an urgent need to distinguish between disturbed and intact habitats. It should be considered whether to incorporate such classification into the existing classification system.

1. In general, because of the various sources of geographical data, issues including mapping scale/precision, age of data, mapping criteria etc. have to be considered carefully when using existing data for habitat classification. Maps overlap and will reveal areas that can be described with two or more habitat classes. Most important is to make sure that all relevant information on the data (sources/scale/age etc) is available and accessible e.g. in the data dictionary.

1. At present there are no fixed agreement between departments regarding the availability and accessibility of digital data. This is desirable.
2. It is important to emphasise that any decision making or advising based on maps, including a natural habitat map, should not be accomplished without some degree of verification of the reliability of the data. This is done by inspecting the area of interest and/or studying recent aerial photographs

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