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Subject: 后海灣一分鐘 (Deep Bay in a Minute) [Print This Page]

Author: HKBWS Suet Mei Time: 22/02/2019 17:38 Subject: 后海灣一分鐘 (Deep Bay in a Minute)

【后海灣一分鐘】一、甚麼是濕地保育區(WCA) 和濕地緩衝區 (WBA)？

后海灣濕地及泥灘是各種水鳥及冬候鳥的重要覓食地及棲息地。七八十年代期間，米埔沼澤區逐漸獲得香港法例的保護，並邀請世界自然基金會積極管理該區的生境。但直至1997年「后海灣地區魚塘生態價值研究」完成後，政府才正式確認魚塘具有重要的生態價值。事實上，魚塘與米埔沼澤區在生態上具有緊密的關連，是后海灣濕地生態系統的一部分。因此，我們應同時保育后海灣相連的濕地及魚塘，包括豐樂圍、南生圍、甩洲、新田、馬草壟等地區，以維持其生態完整性。

隨著后海灣一帶的發展壓力增加，城市規劃委員會(城規會)為后海灣制訂規劃指引(規劃指引編號12)，並成立「濕地保育區」(Wetland Conservation Area)及「濕地緩衝區」(Wetland Buffer Area)，以規管在后海灣地區的土地使用和開發。

濕地保育區旨在保護由大小不一但相連的魚塘所組成的核心區域，而濕地緩衝區則是以保護濕地保育區為目標的緩衝區。在濕地保育區內，除非是保育該區的生態環境，或具有絕對壓倒性的公眾利益而必須進行的基礎設施項目外，不容許任何新發展。濕地緩衝區則在不損害濕地保育區魚塘生態價值的前提下，或許容許一些住宅或康樂發展，以移除現有的開放式存儲用途和恢復一些被破壞的魚塘。
本會認為任何發展項目都必須嚴格遵守濕地保育區/濕地緩衝區的規劃管制，以保護后海灣濕地生態系統的生態完整性。

【Deep Bay in a Minute】1. What is WCA and WBA?
The Deep Bay wetlands and mudflats is a globally recognized foraging and roosting ground for waterbirds and other migrant winter birds. The Mai Po marshes were gradually protected under Hong Kong legislation and actively managed during the 1970s and 80s. Yet, it was not until the Study on the Ecological Value of Fishponds in the Deep Bay Area completed in 1997 that formally recognized the ecological value of fishponds. In fact, the fishponds are ecologically connected to the Mai Po Marshes and form an integral part of the Deep Bay wetland ecosystem. Therefore, the continuous and adjoining wetlands and fishponds in the Deep Bay, including such areas as San Tin, Nam Sang Wai, Lut Chau and Hoo Hook Wai should be conserved in order to maintain its ecological integrity.

As the development pressure increased, the Town Planning Board established the “Wetland Conservation Area” (WCA) and “Wetland Buffer Area” (WBA) to regulate applications for different land use and development in the Deep Bay Area. Under the Town Planning Board Guideline No 12 the WCA was designated to conserve the core area which consists of continuous and adjoining fishponds, while WBA was designated as a buffer zone to protect the WCA. No new development is allowed within the WCA unless it supports nature conservation in the area or is an essential infrastructure with overriding public interest. Residential or recreational development in the WBA, which helps to remove the existing open storage use and/or to restore some of the fishponds and would not have adverse ecological impacts on the WCA may be allowed.

Besides the WCA and WBA, the “precautionary approach”, which states that you should not take an action without being aware of the outcome, and the principle of “no-net-loss in wetland” are also important concepts adopted in Guideline 12.

HKBWS considers that the above planning controls and principles should be strictly followed in order to conserve the ecological integrity of the Deep Bay wetland ecosystem.

【后海灣一分鐘】二、「濕地保育區」(WCA) 和「濕地緩衝區」(WBA) 從何而來？

六十年代起，地產發展開始擴散至新界以至后海灣一帶的濕地，包括其後出現鄰近米埔的錦綉花園私人住宅項目和天水圍新市鎮。1983年的「生發案」中，高級法院裁定只要發展不包括任何建築物，地段擁有人可以把土地用作農業以外的用途，於是進一步鼓勵更多魚塘被填平作各類棕地作業，嚴重威脅后海灣的濕地生態。

隨著港英政府估計鄉郊土地將受到無法預期的破壞，環境保護署於1988年委託顧問公司，研究后海灣地區的自然資源和潛在的環境問題，制訂行動計劃以管理后海灣，並評估不同發展項目以致整體的發展模式帶來的累積影響。報告確認了后海灣濕地的重要性並提出多項保育建議，例如訂立綜合環境管理計劃，並為后海灣設立緩衝區。

1991年，《城市規劃條例》正式加入鄉郊地區的發展管制。規劃署於1992年制訂指引，以管制在后海灣經城市規劃委員會審批的發展規劃，並成立后海灣緩衝區一(BZ1)和二(BZ2)。

米埔內后海灣一帶於1995年正式被納入為「拉姆薩爾濕地」，規劃署於同年委託顧問公司進行「后海灣地區魚塘生態價值研究」，確認魚塘的生態價值。報告建議將連綿一片的魚塘劃為濕地保育區作保育，並將保育區以外的五百米範圍劃為濕地緩衝區。濕地保育區及濕地緩衝區於1999年正式取代BZ1和BZ2，其範圍在2014年隨邊境禁區開放而延伸至蠔殼圍及馬草壟一帶。

2004年，「內后海灣及深圳河集水區」亦被國際鳥盟認可為「重點鳥區」，範圍由白泥及流浮山伸展至塱原等地，包括大部份濕地保育區及濕地緩衝區。

【Deep Bay in a Minute】2. Where did WCA and WBA come from?
Since the 1960s, development pressure started to encroach into the Deep Bay area, with new developments such as Fairview Park and Tin Shui Wai New Town emerging in the 1980s and 1990s. The “Melhado” case in 1983, in which the High Court ruled that land zoned for agriculture may be used for non-agricultural purposes as long as no structure is built, has led to the draining of fishponds for brownfield operations such as container storage that threatened the wetlands in the Deep Bay area.

In 1988, the Environmental Protection Department commissioned a consultant to study the impacts of development activities on the environmental and natural resources of Deep Bay and to develop an action plan for the management of the Deep Bay. The study recognized the importance of the Deep Bay wetlands and recommended conservation actions including the establishment of integrated conservation management plans and buffer zones for Deep Bay.

In 1991, development control in rural areas was introduced under the Town Planning Ordinance (TPO). In 1992, the Planning Department established a set of planning guidelines under the TPO to regulate development applications in the Deep Bay area with Buffer Zones 1 (BZ1) and 2 (BZ2).

In 1995 Mai Po and Inner Deep Bay was recognized as wetland of International Importance under the Ramsar Convention. In the same year the Planning Department commissioned a study on the Ecological Value of Fish Ponds in the Deep Bay Area, which confirmed the ecological importance of fishponds. The study recommended that the continuous and adjoining fishponds should be conserved and to be zoned as “Wetland Conservation Area” (WCA), while a surrounding buffer zone of about 500m wide to be designated as “Wetland Buffer Area” (WBA). In 1999, the BZ1 and BZ2 were replaced by WCA and WBA and was extended to cover the Hoo Hok Wai and Ma Tso Lung area in 2014 after the opening of the frontier closed area.

In 2004, the Inner Deep Bay and Shenzhen River catchment area, including areas of WCA/WBA and other areas stretching from Pak Nai and Lau Fau Shan to Long Valley, was recognized by Birdlife International an Important Bird Area.

【后海灣一分鐘】三、為什麼雀鳥喜愛活躍魚塘？

魚塘的生態價值其實與魚塘的運作息息相關。漁民在收獲塘魚(俗稱「刮魚」)前會先把塘水泵到鄰近的魚塘，這些淺水魚塘吸引候鳥前來捕捉一些經濟價值較低的雜魚和無脊椎動物。我們在這些淺水的魚塘濕地共錄得83種水鳥及依賴濕地的雀鳥，當中更有11種為全球瀕危鳥種，如極度瀕危的勺嘴鷸和瀕危的黑臉琵鷺。降水後的魚塘所錄得的水鳥物種比降水前高出達19倍。

自2012年起，香港觀鳥會獲環境及自然保育基金資助，在新界西北的魚塘展開自然保育管理協議計劃，以確保魚塘每年都會降低水位，並維持該水位至少一個星期。這正正就是「明智使用濕地」的最佳例子，透過與本地漁民合作保育濕地，同時有利經濟和社會方面得以永續。每年參與計劃的養魚戶管理后海灣一帶超過600公頃的魚塘。

但由於魚塘降水主要由市場主導，每一次降水的魚塘只佔后海灣整片魚塘的一少部份，所以供給雀鳥的食物會隨時間和空間而有所改變。我們應保護及維持大量的魚塘運作，以確保每一刻都有魚塘進行降水，為雀鳥提供穩定的食物供應。

【Deep Bay in a Minute】 3. Why birds love working fishponds?
Interestingly, the ecological value of fishponds is related to its operation. When fishermen drain the ponds to harvest their fish, the trash fish (those that are too small to be sold) and other invertebrates left in the shallow water of the pond creates a favourable feeding habitat for waterbirds. 83 waterbirds and other wetland-dependent bird species were recorded utilizing drained fishponds, including 11 globally threatened species. These include the critically endangered Spoon-billed Sandpiper and the endangered Black-faced Spoonbill. The number of waterbird species recorded during drain-down was found to be about 19 times higher than the number recorded before the fishpond drain-down.

In 2012 HKBWS established a Management Agreement with a number of fishpond operators in Deep Bay with funding support from the Environment and Conservation Fund, under which each fishpond must be drained for at least a week per year. This is an example of “wise use of wetland”, where conservation of wetland is achieved through the engagement of the local fishpond operators, as it is both economically and socially sustainable, as well as beneficial for the environment. Every year, fishpond operators participated in the scheme are managing over 600 hectares of fishponds in the Deep Bay area.

However, as the drain down is market driven, the number of drained fishponds at any one time only represent a small percentage of the total, and thus the food supply for birds at fishponds changes over both time and space. Therefore, it is important to conserve a large number of fishponds, so as to ensure there are drained fishponds at any given time in order to maintain the food supply for birds.

[ Last edited by HKBWS Suet Mei at 22/02/2019 17:40 ]

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Author: HKBWS Suet Mei Time: 25/02/2019 17:47 Subject: 后海灣一分鐘 (Deep Bay in a Minute)

【后海灣一分鐘】四、為什麼雀鳥成為魚塘生態功能的重要指標？

由規劃署委託顧問進行的「后海灣地區魚塘生態價值研究」（1997），雀鳥被指定為魚塘生態功能的重要指標，原因包括：
- 雀鳥位於食物鏈高層，涵蓋的地域相對其他物種較廣闊，能夠反映環境的健康狀況
- 雀鳥全年可見，並可直接觀察
- 鳥類分類學較成熟，而且能在一個不造成干擾的距離下辨認鳥種
- 無論在本地、區域或國際層面，雀鳥相對於其他物種有較全面的資料及紀錄
- 雀鳥是后海灣地區重點保育的物種
此外，現時已經累積大量在后海灣地區的雀鳥紀錄供研究及分析。本會自1979年開始在后海灣地區進行水鳥監察。自1997年起，漁農自然護理署一直委託本會在后海灣進行水鳥監察，並將調查增加至一個月一次。長期的鳥類觀察能讓我們了解及估計后海灣雀鳥的數量及趨勢。

【Deep Bay in a Minute】4. Why bird was selected as an indicator of the ecological function of fishponds?
In the “Study on the Ecological Value of Fishponds in the Deep Bay Area” (1997) commissioned by the Planning Department, bird was selected as the key indicator of the ecological function of fishponds, because:
- Birds are at the highest levels in the food web, and presume birds in general require more territorial space, thus they can represent the health status of the environment.
- Birds are present all year round and can be observed directly.
- Birds are taxonomically well known and can be identify at a distance without disturbance.
- Birds are better documented than other wildlife locally, regionally and globally.
- Birds are one of the key conservation targets in the Deep Bay area.
In addition, there is a long dataset of bird records in the Deep Bay area for analysis. HKBWS started monitoring of waterbirds in the area since 1979. It was expanded to monthly waterbird count with funding support from the Agriculture, Fisheries and Conservation Department since 1997. Long term monitoring provides important information on the population and trends of waterbirds in the Deep Bay wetlands.

[ Last edited by HKBWS Suet Mei at 25/02/2019 17:51 ]

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Author: HKBWS Suet Mei Time: 21/03/2019 12:17 Subject: 后海灣一分鐘 (Deep Bay in a Minute)

【后海灣一分鐘】五、米埔和魚塘大不同？

翻開1997年的魚塘研究報告，發現曾經有人將米埔自然護理區和三個魚塘區（包括馬草壟、練板村及甩洲/南生圍）所錄得的雀鳥物種作比較。前者每年錄得223種雀鳥而後者則錄得168種。米埔自然護理區明顯有較多涉禽、海鷗和燕鷗的紀錄，也許因為它較接近泥灘，並有合適的棲息生境。話雖如此，兩個地方在其他鳥種的紀錄上其實相差無幾。而且，大部份在后海灣錄到的瀕危雀鳥如黑臉琵鷺，在魚塘區也有紀錄。再比較后海灣、米埔自然護理區和魚塘區的水鳥數量，不難發現三個地方不同水鳥種類的最高數目都錄得類近的趨勢。由此可見，米埔自然護理區和魚塘區無論在雀鳥種類或水鳥數量的趨勢都十分相似，所以我們應將米埔自然護理區和后海灣一帶的魚塘視為一個完整的生態系統。

我們在2018年為幾種水鳥開展了衛星追蹤研究。研究發現其中一隻小白鷺一年間的活動範圍足足覆蓋了整個內后海灣，包括泥灘、米埔自然護理區和魚塘區。牠甚至在夏天留在后海灣其中一個鷺鳥林繁殖。這次發現恰恰確定了雀鳥不會看到我們為米埔自然護理區劃上的界線；反而牠們只懂得在后海灣一帶尋找最合適的生境。

米埔自然護理區和后海灣魚塘大不同？非也。它們更應被看待為同一個生態系統。

【Deep Bay in a Minute】 5. Any difference between the birds in Mai Po and in fishponds?

In the 1997 fishpond study, bird species recorded in Mai Po Nature Reserve (MPNR) and in three fishpond areas (i.e. Ma Tso Lung, Lin Barn Tsuen and Lut Chau/Nam Sang Wai) were compared. A total of 223 and 168 bird species were recorded in a year in MPNR and the fishpond area respectively. Mai Po had significantly more waders, gulls and terns, perhaps it is closer to the mudflat and has suitable roosting habitats. Yet, other bird groups were similar. Most of the threatened species recorded in the Deep Bay area, such as the globally endangered Black-faced Spoonbill, were also recorded in the fishpond area. When comparing the peak bird counts of waterbirds in Deep Bay, MPNR and fishponds, much the same patterns were observed. This similarity in bird composition and bird abundance pattern suggests that MPNR and the fishpond area across the Deep Bay should be treated as one integral system.

Our recent satellite tracking research conducted in 2018 found that the activity range of one Little Egret within a year can covered the inner Deep Bay, including in the mudflats, MPNR and fishpond area. It even bred in one of the egretries in Deep Bay during summer. This further confirms that birds do not distinguish the boundary at MPNR, but identifies the suitable habitats within the whole Deep Bay area. Therefore, the fishponds and MPNR should be treated collectively as part of the same ecosystem.

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Author: HKBWS Suet Mei Time: 21/03/2019 12:21 Subject: 后海灣一分鐘 (Deep Bay in a Minute)

【后海灣一分鐘】六、荒廢魚塘荒而不廢？這裡會發生甚麼事？

荒廢魚塘泛指沒有人管理的魚塘。這些魚塘不會再有降水的操作，反而會被雨水注滿；一些塘壆缺乏管理及維修，魚塘水位可能會受潮汐漲退影響。塘壆及塘內的植被亦因為乏人管理而叢生。有人認為荒廢的魚塘生態價值較低，但事實上，荒廢魚塘的生境也有很多種，其差異很多時候取決於荒廢時間的長短，以及魚塘周邊的生態環境。

政府1997年的魚塘研究報告早已提出，相對於運作中的魚塘，荒廢魚塘擁有較多蘆葦及露出水面的植物。南生圍魚塘雖然已荒廢了二十多年，但卻仍然孕育大量蘆葦，2011年更有顧問報告評核該區的蘆葦床面積乃是全港數一數二。蘆葦床為不少具保育價值的野生動物提供覓食及棲息地，包括受本地關注的黃葦鳽、受區域關注的中華攀雀，以及全球近危的歐亞水獺。因此，荒廢魚塘的生境特徵與運作中的魚塘不同，其生態功能亦不容忽視。

【Deep Bay in a Minute】6. What happens in the abandoned fishponds?

Abandoned fishponds generally mean fishponds without active human management. There will not be any drain-down regime at the fishponds but instead will become rain fed. The lack of fishpond bund maintenance may cause the fishpond to become subject to tidal influence. There will be no control over bund and emergent vegetation in the fishpond. Some people may think abandoned fishponds are of lower ecological value. Yet, habitats of abandoned fishponds vary a lot and depend on factors including the time of abandonment and the surrounding ecological environment.

The Government’s 1997 Fishpond Study recorded overall higher percentage of reed and emergent vegetation coverage in abandoned fishponds than in operating ones. It also recorded more species of ducks use abandoned fishponds during the winter. Even though some of the fishponds in Nam Sang Wai were inactive for decades and were gradually overgrown with reeds, a consultancy assessment in 2011 commented that it is one of the largest area of reed habitat in Hong Kong. The reedbed provide suitable foraging and roosting habitat for various wildlife of conservation concern, including Yellow Bittern of local concern, Chinese Penduline Tit of regional concern, and the globally near threatened Eurasian Otter. Therefore, abandoned fishponds have different habitat characteristics from operating ones and their ecological functions should not be overlooked.

[ Last edited by HKBWS Suet Mei at 21/03/2019 12:23 ]

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Author: HKBWS Suet Mei Time: 21/03/2019 12:25 Subject: 后海灣一分鐘 (Deep Bay in a Minute)

【后海灣一分鐘】七、魚塘荒廢之迷

隨著房地產發展蔓延至新界，土地的預期價值遠超於魚塘養殖業帶來的經濟回報。后海灣一帶相繼因為土地持有人及地產商選擇土地投機而荒廢魚塘。南生圍在九十年代初開始停止魚塘養殖運作後，土地持有人及地產商屢次申請發展許可，而最近一次有關高密度住宅項目的發展申請，亦被城市規劃委員會拒絕。豐樂圍的魚塘曾經有漁民管理和運作，更曾參與本會的魚塘管理協議計劃，令魚塘運作可以和雀鳥保育並存。然而，城市規劃委員會在2013年向地產商批出發展許可後，地產商不予漁民繼續經營，而魚塘亦於2016年開始荒廢。

當大家都關注如何管理后海灣濕地時，卻不能只將討論範圍收窄至「地產發展項目如何支持濕地保育」的說法。當非法傾倒泥頭和棕地發展屢屢出現在地產商持有的土地上時，我們更應思考地產商有沒有責任妥善管理其土地和租戶，以確保土地不被破壞。此外，魚塘以外的濕地如蘆葦床，也可透過申請政府資助的自然保育管理協議計劃而得到妥善管理。既然魚塘養殖業是善用濕地的一種，亦是本港農業的一部分，政府應主動將位於政府土地的荒廢魚塘恢復運作，或為自然保育緣故積極管理濕地。而且魚塘的生態價值與魚塘運作息息相關，政府更應為本地魚塘養殖業提供更多經濟援助，以確保可持續保育后海灣的雀鳥及濕地。

【Deep Bay in a Minute】7. Why fishponds are being abandoned?

Many fishponds were left inactive due to land speculation by landowners and developers in hope of securing property development right with a much higher return than pond fish culture. Fishponds in Nam Sang Wai were abandoned in early 90s, and since then the land owner and developer continuously sought development permission, yet their recent high-rise residential development proposal was rejected by the Town Planning Board. Fishpond farmers have been managing and operating the fishponds in Fung Lok Wai and even participated the Society’s Fishpond Management Agreement (MA) Scheme to fulfil some operation requirements for bird conservation. Yet, as development permission was granted by the Town Planning Board in 2013, the developer forced the fishpond farmers to leave and the fishponds have been abandoned since 2016.

When talking about the management of wetlands, the discussion should not be limited to how property development can support the conservation of wetlands. Developers and land owners should properly manage their land and tenants to ensure waste are not dumped on their lands. Nature Conservation Management Agreement projects can be applied through funds from the Government for the management of reedbeds and wetlands other than fishponds. As pond fish culture itself is a “wise use of wetland” and a part of our agriculture culture, the Government should reactivate and operate abandoned fishponds on Government land, or actively manage the wetlands for wildlife. Given the ecological value of fishponds is strongly related to fishpond operation, the Government should also boost the economic support to local pond fish culture for sustainable conservation of birds and wetlands in the Deep Bay area.

[ Last edited by HKBWS Suet Mei at 21/03/2019 12:27 ]

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Author: HKBWS Suet Mei Time: 6/12/2019 16:25 Subject: 后海灣一分鐘 (Deep Bay in a Minute)

【后海灣一分鐘】八、后海灣的繁殖鷺鳥

鷺鳥一起聚集及築巢繁殖的地方通常稱為鷺鳥林，即鷺鳥的繁殖地。香港約有20個鷺鳥林，分別有五種鷺鳥定期聚集繁殖，包括小白鷺、大白鷺、牛背鷺、夜鷺和池鷺。牠們築巢地點分佈非常局限，都具保育價值，除了小白鷺和大白鷺的繁殖地屬「區域關注」之外，其餘三種都屬「本地關注」。而后海灣濕地正正是這些繁殖鷺鳥的重要覓食地之一。

在「后海灣地區魚塘生態價值研究」（1997）中，尖鼻咀、米埔村及河上鄉鷺鳥林均被選中為研究對象，以了解繁殖鷺鳥的飛行路徑和其降落的地點。結果顯示鷺鳥們主要會飛往潮間帶的泥灘、運作中或降水中的魚塘，而傾向避開露天儲存場（統稱棕地）、住宅區和建築地盤。牠們大多在築巢地點兩公里範圍內活動，有些因應附近地勢亦會飛至遠達四公里的地方。為了保育這些繁殖鷺鳥，我們應妥善保護牠們的繁殖地、覓食地以及飛行路線。

根據2018年的調查，后海灣地區的三大鷺鳥林分別位於米埔村、東成里及米埔隴村[1]。這三個鷺鳥林的鳥巢數量合共佔全港總數的三分之一以上。它們更位於「濕地緩衝區」（WBA）內或剛剛在WBA界線之外，使WBA成為繁殖鷺鳥的飛行走廊/路線，讓牠們能前往位於「濕地保護區」（WCA）內的覓食地和濕地。因此，WBA在后海灣的濕地生態系統中具其生態功能和角色，應得到妥善的保護，以免受到任何發展威脅。

【Deep Bay in a Minute】8. Breeding egrets and herons in the Deep Bay area

Herons and egrets nest together in colonies called egretries (which is also known as nesting colonies). In Hong Kong five species breed regularly in some 20 colonies, they are Little Egret, Great Egret, Eastern Cattle Egret, Black-crowned Night Heron, and Chinese Pond Heron. The restrictedness of the nesting sites of these species are of Local Concern, except for Little Egret and Great Egret which are of Regional Concern. Deep Bay wetlands is one of the important foraging grounds to these breeding egrets and herons.

In the “Study on the Ecological Value of Fishponds in the Deep Bay Area (1997)”, Tsim Bei Tsui egretry, Mai Po Village egretry and Ho Sheung Heung egretry were selected to study the flight paths of the breeding birds from the egretry and the corresponding landing location. Results showed the birds mainly fly to the inter-tidal mudflats, operating fishponds and drained fishponds, while they tend to avoid places used for open storage (commonly known as brownfields), residential areas and construction sites. Most birds flew less than 2km from their nests, but some can reach a distance as far as 4km due to the surrounding topography of the egretry. In order to safeguard these breeding egrets and herons, the nesting locations together with feeding grounds and flight paths of the birds should all be protected.

In 2018, the three largest egretries in the Deep Bay area were Mai Po Village egretry, Tung Shing Lane egretry and Mai Po Lung Village[1]. The sum of the nests in these three egretries accounts for over one-third of the total number of nests in Hong Kong. These nest locations are within the Wetland Buffer Area (WBA) or just immediately outside the WBA. Besides, WBA serves as a flight path/corridor such that the breeding egrets and herons can access their foraging grounds and wetlands in the Wetland Conservation Area (WCA). Therefore, WBA has its ecological function and role to play in the Deep Bay wetland ecosystem, and should be adequately protected from development threats.

[1] Anon, 2018. Summer 2018 Report: Egretry Counts in Hong Kong with particular reference to the Mai Po Inner Deep Bay Ramsar Site. Report by The Hong Kong Bird Watching Society to the Agriculture, Fisheries and Conservation Department, Hong Kong Special Administrative Region Government.

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Author: HKBWS Suet Mei Time: 13/02/2020 16:26 Subject: 后海灣一分鐘 (Deep Bay in a Minute)

【后海灣一分鐘】九、誰在善用塘壆？誰在利用塘壆？

塘壆是魚塘養殖和后海灣濕地生態系統中不可或缺的一部份。漁民會用生長在塘壆的草餵飼鯇魚，塘壆也是一些水鳥的庇護所，為捕獵昆蟲或啄食種子的雀鳥如鶯、鵐和鷚等提供食物。「后海灣地區魚塘生態價值研究」（1997）曾比較在四種不同塘壆生境裡所錄得的陸生無脊椎動物，結果顯示灌木叢擁有最豐富的物種數目，蘆葦床錄得最高的個體密度，而草地則有最高的生物質（Biomass）。光禿禿的塘壆縱使擁有最低的陸生無脊椎動物物種數目和生物質，但卻為鷺鳥如小白鷺、大白鷺及黑臉琵鷺等提供合適的晚棲地。因此，有植被及沒有植被的塘壆在后海灣濕地生態系統中均有其獨特的生態功能及角色。

然而，為了迎合城市規劃委員會規劃指引的「不會有濕地淨減少」（no-net-loss in wetland）原則，發展商提出移除塘壆以增加水體面積，作為補償因填土興建樓宇所帶來的濕地損失。漁農自然護理署曾就南生圍的房地產發展項目( 規劃申請編號A/YL-NSW/218 )指出發展商所謂的「不會有濕地淨減少」「只計算了發展前後『水體面積』上的差異，而沒有考慮到其大範圍的發展面積和所帶來的生態影響…若然計算現有濕地面積時沒有納入塘壆，將會低估濕地損失的面積。」豐樂圍濕地的房地產發展項目申請亦採用同樣策略，最終卻獲得城市規劃委員會批准興建樓宇，此事件亦促使有環保團體就此提出司法覆核。香港觀鳥會認為發展商就「不會有濕地淨減少」的計算方式有誤導，因此不能接受。

【Deep Bay in a Minute】9. Pond bunds: an ecological fabric or development tactic?

Pond bunds are an integral part of the fishpond operation and the Deep Bay wetland ecosystem. For example, fish farmers use the grass grown at the pond bunds to feed the Grass Carp in the fishponds. Besides, the vegetated bunds serve as a shelter for water birds and provide alternative food sources to insect- and seed- feeding birds such as warbler, buntings and pipits. A preliminary investigation was conducted for terrestrial invertebrates in four vegetation types on pond bunds under the “Study on the Ecological Value of Fishponds in the Deep Bay Area (1997)”. It was found that scrub has the highest taxa richness, reed held the greatest density of individuals, grass has the highest biomass, while bare ground held the lowest in count and biomass of invertebrates among them all. However, from our observation, un-vegetated fishpond bunds also provide roosting habitat for ardeids such as Little Egrets, Great Egrets, and Black-faced Spoonbills. Therefore, both vegetated and un-vegetated fishpond bunds have their own ecological functions in the Deep Bay wetland ecosystem.

In order to meet the Deep Bay planning principle of “no-net-loss in wetland”, developers have tried to remove pond bunds so as to increase the “wetland” area (i.e. water surface of fishponds) to compensate the wetland loss caused by the development. AFCD commented on the previous Nam Sang Wai development (planning application no. A/YL-NSW/218), saying that so-called “no-net-loss in wetland” claimed by the developer “only calculated the difference in area of ‘water surfaces’ before and after development without considering the extensive development area and its ecological impact…omission of the pond bunds in the calculation of the existing wetland area would underestimate the area of wetland loss.” Similar tactic was used in Fung Lok Wai wetland, leading to an environmental NGO to launch a judicial review against the Town Planning Board’s approval of the residential development in the locality. HKBWS considers that such “no-net-loss in wetland” calculation method is unacceptable and misleading.

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