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Chapter 2 HABITAT MAPPING CATEGORIES

2.2

Definitions for Habitat Mapping Categories

The mapping categories was defined and discussed in TR1. The majority of the habitat definitions proposed in TR1 are considered pertinent in providing guidelines for satisfactorily mapping of habitats through supervised classification and usage of existing information. However, the definition for Plantation or "Plantation/Mixed Forest" require modifications based on outcomes of mapping, further liaisons with Government and advice from field surveyors after undertaking habitat surveys. Definitions for the 25 habitat categories are summarised in Table 2.2a (see TR1 for detailed discussions).

Table 2.2a Definitions of Habitat Mapping Categories
Habitat/Feature Type	Mapping Category	Definitions
Natural Terrestrial Habitats	Bare rock or soil	Naturally open rock faces or disturbed lands, or "badlands" denuded of vegetation.
	Grassland	Lands covered predominantly (50% or more) by grasses with no visible woody plants.
	Shrubby grassland	Lands covered predominantly (50% or more) by grasses and contained visible woody plants covering up to 50% of the area.
	Mixed Shrubland	Lands covered with less than 50% grasses with shrubs the major woody life form.
	Baeckia shrubland	Lands covered with less than 50% grasses with the genus Baeckia (Myrtaceae) the predominant plant group.
	Fung shui forest	Lands covered with natural forests over 60 years old and dominated by native species. Often located behind villages, in valleys or near water.
	Montane forest	Lands covered with natural forests above 600m above sea level.
	Lowland forest	Lands covered with natural forests below 600m above sea level.
	Plantation or Plantation /mixed forest	Lands covered with tree species varying in size from low saplings to mature trees which are in recognizable rows from the air. Areas where the definition of "in recognizable rows from the air" cannot apply (eg plantations have become mixed plantation forests and intermingled with other spectrally and visually habitats, making identification using satellite imagery and aerial photos impossible) and require field surveys to supplement the mapping, the pattern in and type of plant species used for tree planting site formed the basis for justification of this habitat ⁽²⁾.
Natural/Artificial Freshwater and Intertidal Habitats	Freshwater/Brackish Wetland	Lands covered with shallow waters and dominated by emergent hydrophytes.
	Natural watercourse	Consists of rivers and streams experiencing natural flow patterns in unchannelised beds and banks.
	Modified watercourse	Consists of channelised rivers, streams and other waterbodies, which are often without natural banks and beds, and are not subject to a natural flow patterns (eg drainage channels, nullahs and reservoirs). Rivers with substantial abstraction of water for irrigation or domestic use. Watercourse with "very bad" water quality identified by EPD⁽³⁾.
	Fishpond/Gei wai	Fishponds are small artificial lakes that have been constructed for the purposes of growing freshwater fish. Gei wais are small artificial lakes which contain brackish water and are often flushed through tidal action.
	Mangrove	Highly productive intertidal areas that support high biological diversity and which are know as breeding and nursery grounds for a range fauna.
	Intertidal mudflat	Areas of fine-grained sediment (ie silt or finer) which lie between the high and low tide marks and which are not covered by seagrasses, mangroves or typical wetland vegetation.
	Seagrass bed	Shallow intertidal or subtidal areas dominated by one or more species of specialised marine grasses.
	Sandy shore	Areas of sandy sediment (coarser than silt and up to and including cobble-sized rocks) between the high and low tide marks, and areas with 50% or more of the area consists of exposed sand or rocks equal to or smaller than cobbles.
	Rocky shore	Areas of stable (non-mobile) rocks larger than cobbles between the high and low tide marks, covering more than 50% of the area.
	Artificial rocky/Hard shoreline	Man-made intertidal hard shore habitats, eg seawalls, jetties, groins and piers.
Disturbed Areas which Provide Some Habitat	Cultivation	Lands currently under cultivation, ie actively agricultural land (eg rice paddies or areas farmed for vegetables), and lands not currently under cultivation and/or abandoned for cultivation.
	Golf course/Urban park	Areas which consist of existing golf courses and urban parks, and areas under development for golf courses and urban parks. Urban parks include all recreational parks under the governmental management of the Provisional Urban council and the Provisional Regional Council, and the non-governmental management of private enterprise.
Disturbed Areas which Provide Little if any Habitat	Rural Industrial Storage/Containers	Areas in which large number of containers or other commercial/industrial materials are stored (generally considered as "black spot" areas by the Government).
	Quarry	Areas which are being or have been excavated for rock.
	Landfill	Areas used for disposal of solid waste and may be either active or inactive.
	Other^a	Areas occupied by urban or other highly modified habitats, including scattered buildings mixed with cultivation, abandoned cultivation and/or forest.

(1) As defined in TR1 (p.14), "rare" species include species which are regionally rare, locally rare, protected and/or confined to habitats in Hong Kong. As indicated in TR1, it was intended to collect rare species data based on a species list provided by the HKU Biodiversity Team (as indicated in TR1), however, as ERM did not receive the relevant information from the HKU Biodiversity Team, the rare species information was collected based on existing information and expert knowledge of the Field Survey Team. Additional information on "rare" species obtained from ecological field surveys was extracted as a layer of points for incorporation with the habitat map.

(2) As the majority of plantations have become mixed plantation forests and intermingled with other spectrally and visually similar habitats, they are unable to be identified and accurately mapped using satellite imagery and aerial photographs. This category would therefore require field surveys to supplement the mapping.

(3) Classification of watercourse based on the most recent EPD River Water Quality data.

a: Definitions of the habitat have been modified to include the "Buildings" category.

2005

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最近修訂日期: 二零零五年十二月二十二日