Review on the Ecological Value of Agricultural Land
(ACE Paper 39/98)
for information
Purpose
At the meeting of the Advisory Council on the Environment (ACE) held on 27 April 1998, a member requested the Agriculture & Fisheries Department (AFD) to provide an information paper on the potential ecological impact of the continuing loss of agricultural land due to development in Hong Kong. This paper intends to provide some general information on this matter.
Agricultural Policy
The Government adopts an agricultural policy of promoting modern, efficient, safe and environmentally acceptable farming on land zoned for agricultural use or rural activities including agriculture. The Government does not give subsidies, nor does it seek to protect local agriculture from the free operation of market forces. There are no predetermined production targets. Rather, the Government provides the basic infrastructure and technical support necessary for the development of farming and leaves it to adjust to market forces.
In view of the free market agricultural policy and the absence of pre-determined production targets, the Government has not set aside artificially a minimum amount of land for agricultural development. Whether agricultural land is actually used for agricultural activities is primarily determined by market forces.
Nature and Characteristics of Agricultural Land
Strictly speaking, agricultural land cannot be classified as a specific type of habitat and agriculture is not a kind of conservation activity. Agriculture is a form of rural land use involving various activities primarily aiming at food production such as livestock farming, field crops cultivation, fruit growing, horticulture and aquaculture. A rough breakdown of the agricultural land use in 1997 is as below:
|
Use
|
Area (hectare)
|
Percentage
|
|---|---|---|
| Vegetable |
790
|
10.60%
|
| Flower |
290
|
3.90%
|
| Field Crop |
40
|
0.50%
|
| Orchard |
670
|
8.90%
|
| Ponds |
1,410
|
18.80%
|
| Fallow |
4,290
|
57.30%
|
| Total |
7,490
|
100.00%
|
Most agricultural land in the territory is leased land and its use is subject to rapid changes due to market forces and economic considerations. Depending on the market situation, the type of agricultural activity undertaken on a piece of land could change within a short period of time. Active agricultural land may become fallow and vice versa at any time. Moreover, agricultural land may be changed to other uses that are permissible under the lease conditions or after obtaining approval from relevant authorities.
Ecological Value of Agricultural Land
From an ecological point of view, agricultural land may have the characteristics of different habitats depending on the type of agricultural activity undertaken at the time, such as woodlands (e.g., orchards), wetlands (e.g., fish ponds, blood worm ponds) and built-up areas (e.g., chicken farm). However, the term "agricultural land" in many EIA studies usually refers to open fields used for cultivating vegetables and field crops. Since the agricultural activities on agricultural land may change depending on market forces, the ecological characteristics and functions of agricultural land may not be permanent and are subject to change.
From an ecological perspective, agricultural land in general is subject to human influence or disturbance (e.g., ploughing, weeding, harvesting, application of agrochemicals). Moreover, wild animals or plants occurring on agricultural land that would affect production negatively are treated as pests or weeds and would be eradicated. Only those not appreciably affecting production would be tolerated by farmers. Therefore, agricultural land is not in general considered to have high ecological values. Similar views have been reported in many EIA studies previously endorsed.
By applying the criteria for evaluating a site/habitat listed in Annex 8 of the Technical Memorandum on EIA Process (TM), the evaluation of the ecological value of agricultural land is shown in the table below. A similar approach was adopted in the information paper on "Ecological Impacts and Proposed Mitigation in the Kam Tin Valley" prepared by the Kowloon-Canton Railway Corporation and presented to ACE on 23 March 1998.
| Criteria | Evaluation |
|---|---|
| Naturalness | Agricultural land is created artificially and subject to continual human modifications. |
| Size | Most agricultural land in the New Territories is of small plot sizes. However, large and contiguous areas of small agricultural plots can still be found in the major agricultural areas such as Shap Pat Heung and Kam Tin. |
| Diversity | Normally, only a few varieties of crops or livestock are cultivated/reared. Agricultural land usually harbours low diversity of wildlife due to disturbance by agricultural activities. |
| Rarity | Agricultural land usually does not support rare flora and fauna. |
| Re-creatability | Agricultural land can be easily recreated. |
| Fragmentation | Due to multiple ownership and small plot size, different adjoining agricultural plots may be managed differently. It is not uncommon in the territory that agricultural land is interspersed with other land uses such as factories and open storage. However, in the major agricultural areas, areas of rather uniform open fields can still be found. |
| Ecological linkage | This would depend on specific site locations and conditions. |
| Potential value | Potential is limited by multiple ownership, continual human influence and changes of activities as a result of market forces. |
| Nursery/breeding ground | In general, agricultural activities will prevent wild animals from breeding on agricultural land. |
| Age | This criterion is not readily applicable as agricultural land is often subject to continual human modifications. |
| Abundance/richness of wildlife | As agricultural land is primarily used for agricultural production and wildlife uses are discouraged, it usually does not support abundant wildlife. |
The above evaluation indicates that agricultural land is in general not considered as ecologically important in many aspects such as naturalness and diversity. Moreover, agriculture in overseas countries is often considered as a source of impact to the natural ecosystem as agricultural activities may homogenize landscape, encroach into natural habitats, transform ecosystems, practise monoculture, use agrochemicals, etc. There are relatively few studies in the territory or elsewhere concerning the ecological impact of loss of agricultural land. As discussed in paragraphs 6 to 8 above, agricultural land is a highly selective and man-made environment and is generally not considered as an ecologically important habitat. Therefore, loss of agricultural land generally is not assessed to have unacceptable ecological impacts in ecological assessments of EIA studies.
Nevertheless, the contribution of agricultural land to the rural landscape should not be overlooked. Agricultural land forms part of the mosaic landscape in the rural areas and such mosaic landscape may provide food and shelter for some wildlife. Moreover, some traditional farming methods or systems may maintain some diversity of wildlife. Agricultural land may also provide certain micro-habitats (e.g., bunds, ditches) that can be utilized by some wild flora and fauna, in particular those opportunistic species. In some specific cases, agricultural land abandoned for long period of time has turned into important wildlife habitats through natural ecological succession. However, it should be noted that such ecological benefits may be short term and not sustainable because of the nature of agricultural practice. Moreover, the existing agricultural activities (including fallowing) may change at any time. Under the existing free market system, the Government could not and would not intervene.
The Way Forward
As pressure for development is high, loss of agricultural land to non-farm development is unavoidable. A framework has to be developed to plan for landuse strategically in order to ensure the efficient use of our valuable resources. In drawing up such a framework, the Administration will not only meet their development objectives but also give full recognition to environmental objectives. Such is indeed the objectives of Planning Department's Planning and Development Studies on North East New Territories and North West New Territories. It is expected that more detailed investigation on the zoned agricultural land will be taken up in the context of these strategic studies, with a view to minimize impacts on good quality agricultural land and releasing the non-arable land for compatible uses where appropriate, through the process of comprehensive land use planning.
The conservation value, including that of agricultural land, should be evaluated based on scientific grounds. Studies on the various important habitats in the territory such as "Ecological Study of Freshwater Wetland Habitats" commissioned by AFD, the "Study on the Ecological Value of Fish Ponds in Deep Bay Area" commissioned by the Planning Department and the "Biodiversity Survey" by the Hong Kong University may form the basis of mapping out Hong Kong's important ecological areas, including those identified in agricultural lands.
For individual development proposal affecting agricultural land, the current EIA process is considered adequate. Ecological impacts will be assessed and evaluated together with other environmental impacts under the existing EIA system. Impacts on agricultural land and any other types of wildlife habitats will be evaluated objectively against the criteria listed in Annex 8 of the TM.
Agriculture and Fisheries Department
September 1998
