As indicated in Section 3, the conservation ranking system devised for this baseline survey was to provide a means by which conservation values of different areas, representing different features, can be ascribed, mapped and compared. The system has incorporated four components, including ecological, heritage, recreation and landscape.

It was proposed in TR1 (and summarised in Section 2.3 of this report) that an indicative ecological value was tentatively assigned to each of the habitat types defined for mapping. These classifications were further refined through ecological field surveys under this baseline survey and through the use of existing information, including the HKU Biodiversity Survey CD-ROM database.

Among the 1,051 sub-sites surveyed for this study, a total of 157 sub-sites were found to require adjustment (upgrade/downgrade) after field assessment (Section 7.1). In addition, ecological value of habitat polygons were also justified based on existing ecological information (Section 7.3). There were 40,095.0 ha of habitats classified as of high ecological value which represented 35.9% of the total mapped area (Table 9.4a). Among these "high" value areas, a total of 11.7 ha of habitats were considered as possessing "unique feature(s)" and thus deserved the designation of an asterisk "*" (ie graded as high*) (see Table I1 of Annex I for details on "unique feature(s)"). "Medium" value habitats comprised 19,926.2 ha (ie 17.8%) of the total land area mapped for Hong Kong. "Unique feature" was also identified in one of these medium-value habitats and an ecological value of medium* was assigned (see Table I1 of Annex I). "Low" and "negligible" value habitats comprised, respectively, 28.2% and 18.1% of the total land cover. The results of ecological ranking of habitats are illustrated in Figure 9.4a. Conservation assessment was also undertaken for the other three mapping components, ie heritage, recreation and landscape (see Section 8 for details), and their ranking results are also presented in Figure 9.4a.

The high ecological value areas are classified in Table 9.4b. They are mainly composed of forest and shrubland habitats (including fung shui forest, montane forest, lowland forest and mixed shrubland), inland water habitats (including freshwater/brackish wetland, fishpond/gei wai and natural watercourse) and coastal habitats (including mangrove, intertidal mudflat and seagrass bed). Small areas of Cultivation, Grassland, Shrubby Grassland, Plantation or Plantation/Mixed Forest and Urban Park have also been identified as high ecological value habitats.

The majority of the linear shoreline habitats (75.7%) were identified as of medium ecological value (Table 9.4c). The remaining coastline was ranked either as high (0.3%) or low (24.0%) ecological value habitats. "Unique feature(s)" were also identified for both "high" and "medium" value shore types (see Annex I for details). The "high" value coastline included 2.1 km of Sandy Shore and 0.84 km of Rocky Shore (Table 9.4d). The rankings of the linear habitats are shown in Figure 9.4a.

Table 9.4d Linear Habitats Ranked as of High Ecological Value
Habitat Type	Total Length (km)	Percentage Length Cover (%)
Sandy Shore	2.1	0.19
Rocky Shore	0.84	0.07
Total	3.0	0.26

The Study Team has made use of the HKU Biodiversity Survey CD-ROM database on "rare" plant species by overlaying the "rare" plant records on the habitat map in an attempt to adjust (upgrade) ecological value of habitat polygon(s). However, the outcome of the process showed that a total of 16,821.8 ha of land area would be upgraded, including 8,616.3 ha of highly modified, urban area (ie "Other" category), which is very unlikely to reflect the situation (see Section 7.2). The locations of "rare" plant species identified from the HKU CD-ROM database are presented in Figure 9.4a.