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Old 07-05-07, 07:20
Gong Wooi Khoon Gong Wooi Khoon is offline
Join Date: Dec 2005
Posts: 8
Default Scientific knowledge necessary, Matang management can be improved

We are approaching the end of the GEF/UNEP SCS mangrove workshop and during the general discussion on the mangrove management system in Matang, it was agreed that scientific (including economics and social science) knowledge IS necessary for effective management. It was also agreed that whilst the Matang mangroves may be the best managed in the world, there is room for improvement and various suggestions were made. The gist of our discussion is appended below:
Matang Mangrove Management – General Discussion 7 May, 2007
Led by: Ong Jin Eong
Rapporteur: Gong Wooi Khoon

1. Rotation
Rotation in Matang is 30 years.
How to determine rotation?
Go to forest and study GBH x age and MAI x age to pick when MAI is max.
Matang system – harvest is not at MAI (highest growth rate) which occurs around 15 years and not 30 years. But system good ecologically because animal populations & some other ecological aspects less disturbed with longer rotation.

2. Thinnings
Planting at planting density of 1.2x1.2m gives around 8000 trees/ha. British decided on certain ages of thinning to get some income instead of waiting till the end of the rotation. But at 15 years (1st thinning as practiced now), a lot of dead trees already. So what to do?
No. of trees vs time – get a reverse J curve. Refer to Gong et al paper on demography – around 12 years or so, many trees have died. So minimize wastage by thinning at earlier age. But is the size big enough for commercial use? At 20 years, also lots of dead trees earlier so maybe can thin earlier like at 18 years. No problem with size then. Looking at natural thinning, you can also determine what is a good number to remove.
Year 1 8000 trees
Year 15 7000 trees (some death)
Half removed so 3500 trees left.
Year 20 3000 trees (some death)
Half removed – around 1500 trees
Year 30 Around 1400 left

3. Ecology
3.1 Weeds
When Achrostichum grows in gaps created after harvest, it forms a dense clump so Rhizophora cannot regenerate. Formerly, the Achrostichum clumps were removed manually but now weedicides are used. What is the impact of this on the environment and on other flora and fauna?
3.2 Monoculture
Monoculture of Rhizophora in Matang. Associated problems of monoculture – decreased biodiversity, disease outbreak etc. But in a way, monoculture not so bad as mangroves grow in zones naturally most of the time so OK to have monoculture of Rhizophora in the Rhizophora zone. But in Matang, Rhizophora is grown in zones that naturally are not dominated by Rhizophora naturally. Perhaps this would affect the growth rate (economic consideration) and certainly decrease the biodiversity (and ecotourism).

4. VJR
The purpose of a VJR in many cases is to keep the biodiversity ( a baseline showing what was originally there) and also to act as a seed bank.
What about the VJR in Matang – is it even different from the planted forest? Participants observations/comments:
Cheerawat - Molluscs population higher in VJR,
Bert - Trees bigger and older.
Bert - No Nypa reserve (Answer: not the purpose of Matang – but Nypa can be commercially important so depends on each country)
Phuong - Important to know the aim of the VJR – the Matang VJR is too small for seed bank. (Answer: in Matang purpose is to keep a small area of the “natural” forest as is done in terrestrial forests, but in mangroves, naturally occurring species depends on zones so having just one VJR i.e. one zone then fewer species. Need to improve – perhaps having bigger VJRs or in different zones).
Bansok - Need to have reserves in different zones perhaps including mudflats.
Bansok - What is the maximum size of mangroves that can be converted to other use in any area? (Answer: cannot give a number. Depends on area. Have to monitor each area – use concepts like carrying capacity, limits of acceptable change etc. A manager needs to understand scientific, economics and social aspects (multi-sectorial) to write a proper management plan. Certain decisions may favour certain sectors e.g. fisheries over forestry – you have to make the decisions depending on the purpose of the management and explain your decisions and actions to the different stakeholders.
Suhaili - Matang VJR – is this conserving gene pool? Is the size too small? What is the minimum size? (Answer: minimum size varies depends on purpose and area).
Suhaili - How about having arboretums? (Answer: arboretums is also a terrestrial concept – no zones. Ok if the purpose is to put together many species in one small area for tourists but not for conservation of species – conservating of different zones is necessary then).

5. Economics
We know the price of cockles, some fish, dried prawns, charcoal, poles etc. Is charcoal underpriced? Why?
Participants’ comments:
Mai - Price for charcoal is low because of government subsidy. Externalities not taken into consideration. (Answer: the government pays for salaries for officers and workers for replanting and looking after the mangroves for 30 years, infrastructure etc. So, government should include this as part of the cost. The producers of charcoal should be charged more to cover government costs and they can maintain their profits if they sell charcoal at a higher price).
Mai - There is also environmental cost. (Answer: yes and the details are not worked out as yet. Market failure because of government subsidy? Government also provides social aspects like education of tourists and students. It is necessary to have an economist as well as scientists on the team working out management plans so that the plan is economically sound for the long term as well as reduce environmental costs).
Gate price of charcoal is RM800 per hectare. Someone wants to clear mangroves to make prawn ponds to sell prawns at RM20 per kg – much more revenue than charcoal. So why keep mangrove forests for charcoal instead of converting to other uses? It is therefore important to increase the price of charcoal so that economically, charcoal production compares better. Of course, we keeping the forest (for charcoal production has other uses (remember goods and services lecture). Also the government should provide equity.
Participants’ Comments;
Suhaili – as we saw during our field trip, many people use mangroves for education and ecotourism purposes. How much should the government charge for such services. (Answer: for ecotourism, the forestry department can work out the charges. But for education and also for the local population, the government should perhaps provide this free of charge).
Bert – yes, should charge eco-tourists e.g. chalets charges to be equal to hotel charges. (Answer: depends on individual governments and sites. Decide at a policy level what to do e.g. perhaps Matang will attract more tourists to Malaysia so indirect benefits already).

6. Is knowledge of science (including economics) needed for effective management of mangroves?
Yes, science is absolutely necessary for effective management as shown by the discussion over the last 2 weeks and also in today’s discussion. It is necessary for hard scientists, economists and social scientists to work together.
Participants comments
Phuong – yes, we need to fit in data into management and policy. (Answer: we need a multi-sectorial team for effective management. We need scientists, economists, forestry workers, fisheries workers, government officals etc to work together for effective management).
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