03 October 2011

Learning about Mandai mangroves from Dr Yong

It's a treasure to spend time with Dr John Yong as I always learn so much from him. Today, he took time from his busy schedule to share astonishing insights into Mandai mangroves with Rick and I.
Dr Yong starts teaching us even before we enter the mangroves. Pointing out the signs of where the back mangroves used to be before they were cleared for kampungs and the railway.

Dr Yong also pointed out this Ceropia tree, a non-native tree, which he highlighted could become a danger to our mangroves as it is salt tolerant. It could displace some of our native back mangrove plants. I found this recent paper about The distribution and ecology of Cecropia species in Singapore (pdf) with more details about the trees, which originally come from the tropical Americas.
As we ventured into the lovely mangroves of Mandai, Dr Yong points out the importance of the presence of epiphytes. These include Ant house plants (Dischidia sp.), the Critically Endangered climbing Kalak kambing (Finlaysonia obovata), climbers like the Mangrove wax plants (Hoya spp.) but most especially, mistletoes and the awesome Baboon's head! This is a rare ant house plant, there's more information in this paper Tuberous. epiphytic, Rubiaceous myrmecophytes of Singapore (pdf).
Dr Yong shows us a Bakau kurap (Rhizophora mucronata)! Rick and I had been looking for this and totally missed it. From Dr Yong, we learnt more about how trees can be tricky and look different depending on the conditions where they grow.
Dr Yong finds a Tengar merah (Ceriops zippeliana)! Wah, I missed that in my wanderings. This tree species was first described by Dr Yong and his colleagues in 2009.
The small tree even had a propagule with the distinctive red collar! How exciting!
Today, I learnt the term 'seedling shadow', which shows that the current flows have changed so that the seedlings are not flushed out away from the mother tree. This situation is not ideal for the baby plants or the mother tree as they will compete for nutrients and space.
Dr Yong also shared extensively about what might kill mangrove trees. An area of 'die back' is often caused by insect attack which may kill trees already weakened by environmental changes. For a proper understanding of what is going on, he stresses the importance of all the relationships within the mangroves: plants, animals, sediments, nutrients, water flows and more.
The presence of Nipah palms (Nypa fruticans) also tells us that more about the extent of erosion in a mangrove.
Oh how exciting! Dr Yong has found a mistletoe growing on a Buta-buta tree (Excoecaria agallocha)! A healthy mangrove will have many epiphytes. The lack of these may reflect a missing bird disperser or some other ecological imbalances. Next time I come with Rick, I'll have to drag out the long lens to try to take photos of these elusive plants.
Dr Yong has an awesome guidesheet on mistletoes which he has kindly put online for everyone to use.
Comparative Guide to Mistletoes by JWH Yong
On the way home, Dr Yong points out to me the remains of an epiphyte. We need to look out for such signs.
Another important indicator of a good mangrove is the presence of the Vulnerable Jeruju (Acanthus volubilis) which is distinguished by leaves which are not as prickly as the other species.
Dr Yong is constantly teaching us about plant identification, how the different species are distributed, how various plants, animals interact, the influence of currents and flows, and lots lots more. My brain is exploding! And I think Rick's too.
All too soon, we reach the site where Rick's team is working hard at studying the trees. Dr Yong has presents of his wonderful 'blue' mangrove guidesheets that are invaluable to all of us wanting to learn more. But there's nothing like learning from Dr Yong in person.
Dr Yong has a long chat with the team which today includes Dr. Baliji and Ms. Iona Soulsby, and of course, Wei Kit.
Wah, on the way back, Dr Yong finds another Tengar merah. It's a young tree!
A closer look at the young Tengar merah.
We also passed by some other studies being done by Rick's lab. These are marked off with rope. Please don't step inside the study area.
Dr Yong has given Rick and I lots to think about. And also some homework to go visit some other mangrove sites like Lim Chu Kang to better understand Singapore's mangroves.

Mandai mangroves is a tranquil, magical place! Home to many amazing mangrove trees and plants. The work done by Rick and many others will hopefully go towards conserving it.
Dr Yong's guidance and influence in this is an essential element too. Thank you Dr Yong for spending time and sharing so much with us! And it was also great to catch up with Chua JC who is a magician with mangrove seedlings and cultivation. Mangroves are fascinating and the people who love them are so much fun to be with.

More about Dr Yong's 'blue' mangrove guidesheets with links to downloads on the Celebrating Singapore's Biodiversity blog.


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