Taiwan: Anping Harbor Mangrove Restoration Project at Tainan City

Project Stage:
Completed

Start Date:
1998-06-01

End Date:
2005-12-01

Primary Causes of Degradation

Degradation Description

The third stage of Anping harbor’s construction resulted in the degradation of the entire mangrove forest around the small fishing community.

Project Goals

The main goal of this project is to restore the R. stylosa and Lumnitzera racemosa mangrove species, destroyed by harbor construction, and to plant Kandelia candel, a species dominant in north Taiwan. This project tries to establish a high biodiversity mangrove ecosystem within an urban wetland, in order to reach the goals of ecological conversion and environmental education.

Monitoring

The project does not have a monitoring plan.

Stakeholders

The primary stakeholder in this project is the Kaohsiung Harbor Bureau, which is a subordinate of the Ministry of Transportation and Communications.

Description of Project Activities:
Lungkang community channel -- The planting soil near the channel was wet, and we directly sowed a mix of R. stylosa propagules and L. racemosa seedlings (six months old) during the spring rainy days. In the mean time, we planted Sesuvium portulacastrum on the dry slope, in hopes of preventing soil erosion. Chienkang road mangrove protection area --We used PVC planting pipes to restore mangroves in a flooded area. The PVC pipes had an inside diameter of 10 cm, and were cut to lengths of 150 and 50 cm. Workers drilled five to ten small holes along the whole length of each pipe to allow water exchange. In July 1998, the 150 cm pipes were driven into the soil to a depth of 50 cm in the deepwater area. The 50 cm PVC pipes were placed (with 20 cm inserted into the soil) in a small flood area where the highest flooding was approximately 50 cm. Each pipe was filled with muddy sediment from the surface, creating an artificial bottom, and the R. stylosa propagules with new roots were then planted into the top of the PVC pipes.

Ecological Outcomes Achieved

Eliminate existing threats to the ecosystem:
Lungkang community channel --L. racemosa grew very fast, and 30 months after planting, the average tree height was 200 cm. The directly sown R. stylosa propagules had a lower tree height (80-120 cm). During the restoration period, many A. marina seedlings were established by natural regeneration, and now, three mangrove species have presented beautiful scenery. Chienkang road mangrove protection area --At the shallow area of the Cheinkang site, we directly sowed R. stylosa propagules and planted L. racemosa (ten months old) seedlings under an A. marina tree canopy, at the edge of the forest and at the heavy scour opening small area. Directly sowing R. stylosa propagules among Avicennia trees has given a survival rate of only 30%. The high mortality rate is due to polluted soil, algal damage and heavy water turbulence. However, some saplings have grown very strongly, especially those with abundant prop roots on the favorable fringe sites near the waterway. Eight years after planting, the saplings reached a mean height of over 400 cm, with many propagules emerging. L. racemosa seedlings had a survival rate of 62.4% in the first year. The seedlings grew to a height of 110 cm and flowered. Unfortunately at the flooded area of the Cheinkang site, due to serious multiple stresses, the seedling survival rate for this project was less than 5% after two months. The area was replanted several times during November 1998 and November 1999 with R. stylosa propagules and L. racemosa seedlings. Field investigations show that some vigorous R. stylosa seedlings grew extremely well in 50 cm PVC pipes, with a seedling height of 85-110 cm. The proliferating prop roots were established in muddy soil, which provides stability and essential nutrients, and the first propagule was noted on the seedlings three years after planting (photo 29). Eight years after planting, the height of R. stylosa saplings was over 5 m, and they were in a green, healthy and vigorous state. The R. stylosa container seedlings replanted in the 150 cm PVC pipes at the Cheinkang site also grew well, reaching a height of 75 cm and producing several prop roots. Four years after planting, their prop roots gradually reached the bottom soil. The survival rate of L. racemosa seedlings grown in 150 cm PVC pipes was around 80%, and the seedlings produced fruits in the first year. However, the seedling height was only 60 cm throughout the first three years.

Factors limiting recovery of the ecosystem:
Lungkang community channel-- The whole area was intended to be the container yard of Anping Harbor, and only one small channel could be provided for mangrove restoration. However, the position of this channel was very close to boat anchorage, and fishermen worked nearby everyday. Soil here was very hard, with high salinity and a lot of oyster shell present. Basically, this is not the typical habitat for mangrove growth. Chienkang road mangrove protection area-- At the shallow areas, limiting factors include a large amount of garbage, fishery waste, algae, heavy scour in winter, oil and chemical material pollution due to the industry area nearby. High salinity was also a factor, as was the flourishing canopy of A. marina, which suppressed the saplings by limiting available sunlight. At the flooded areas, the major limiting factor was a lack of soil for seedling establishment, but an abundance of garbage, bamboo poles floating on the water surface, and heavy water turbulence by boats also limited success.

Socio-Economic & Community Outcomes Achieved

Key Lessons Learned

1. It is important to understand the characteristics (including tolerance of salinity, flood and temperature) of each mangrove species in advance. Directly sowing propagules or planting seedlings at the proper position and during the right season would increase the chance for successful restoration.
2. It is necessary to culture L. racemosa seedlings at a nursery in advance (6 – 9 month old container seedlings). The advantage of directly sowing R. stylosa propagules is that it is an easy and cheap method. I recommend this is the best method for mangrove restoration according to this project.
3. Each mangrove species grows very fast, and in this project we planted a mixture of mangrove seedlings with a high density. Four years after planting, the competition showed between individual trees, so I suggest thinning is the most important work after restoration.
4. This project has shown that PVC pipes may be an effective, cheap and easy method for planting mangroves at flood areas. However, there are still many problems. For example, in the initial stage, many deep fish habitats have been in the tray circle, affecting the erection of 150 cm PVC pipes. In the later period, many barnacles attached on the prop roots, and this might affect the growth of sapling in the future.
5. R. stylosa is the only species that can grow in PVC pipes because of its dense prop root. L. racemosa, K. candel and A. marina are not proper species to grow in PVC pipes.
6. PVC pipes could be used at flood areas where the water depth did not exceed 50 cm, and also at polluted sites. However, PVC pipe becomes fragile in salty water and sun light, which may limit sapling growth.

Long-Term Management

The restoration project was completed in 2005, and no funding has been received to maintain this habitat. The administrative right for the project area will transfer to the Tainan City Government, and the government may cooperate with a local conservation organization to plan a conservation park for leisure, bird watching and environmental education.

Sources and Amounts of Funding

approximately 245,000 USD The Kaohsiung Harbor Bureau provided 8,820,000 NT$ (approximately 245,000 USD) for the project. All funding was used for mangrove restoration, environment monitoring (soil, water and vegetation), habitat maintenance (thinning and cleaning waste on land and at the water area), and some scientific research.

Other Resources

Kuei-Chu Fan
National Pingtung University of Science and Technology, Deptment of Foresty
Email: email: fankc@mail.npust.edu.tw

Primary Contact

Organizational Contact