Rengas-attack

Another itchy and sleep-less week, this time not of the ticks but the notorious Rengas, a plant in the mango family (Anacardiaceae). Urushiol, an oil found mainly in the Anacardiads, causes an allergic skin rash on contact. Unlucky ones, like me, have worse reaction. But some people are even sensitive enough to get allergic reaction just from eating mango!

Just by brushing against the leaves. As bad as tick bite, if you can imagine.

Urushiol-induced contact dermatitis

The name Rengas actually refers to trees in the genera Gluta and Semecarpus. Here I refer the name to Gluta wallichii (I have been using this name to curse, and it really sounds like bad words). The Wallich's Rengas is actually quite common in our forest, especially at BTNR (70 big trees recorded in my survey), and they can grow quite big (the biggest Rengas I recorded is 78cm in diameter). However, we normally came across (and "kissed" by) saplings of our height. It is not difficult to spot them. Just look out for "black spots" (dried sap), just like those on mango skin.

Leaves of a Rengas sapling, ca. 30cm long (smaller and stiffer in big trees).

Some vegetative characters to identify Rengas.

Rengas' bark fissures like Seraya, but normally scattered with its infamous tell tale sign. Don't anyhow hug a "Seraya" if you are not sure what it is!

It's rare to find them fruiting, like most other rainforest trees. But if you see something like this in the future, it could be Rengas fruit. Picture here is the Rengas-like fruit of Swintonia schwenkii, a cousin of Rengas. See here for a dried Rengas fruit taken by lekowala at BTNR.

It's my laziness (of not wearing long) to be blamed for my rash, not Rengas. After all, at least we can spot a Rengas and avoid it, can't do that on ticks.

No matter what, I still love mango and cashew nuts.

How big can a forest tick grow?

According to Wikipedia, ticks undergo a lifecycle of several stages. Those we encountered (and got bitten most of the time) are the nymphs (ca. 1-2mm) and some perhaps larvae. So, just how big can a forest tick grow? I was quite intrigued by this question as I never got bitten by an adult one before. Actually, I'd never want to be bitten by one as I can't imagine something as big as the adult dog ticks (ca. 5-8mm) I used to remove from my dogs crawling over and penetrate my skin - unthinkable!

I was lucky enough not to get bitten by any tick yesterday (even when I walked almost the whole reserve, as opposed to the day I last work there - only in a 20m x 20m area) yet caught an adult which was "trying to feed on my pants"!

As big as a dog tick, just flatter and more brownish. My poor North Face Paramount.

Tough sucker, won't let go easily and need to be removed carefully

This is why - barbs along the mouthpart!

Rather cute, actually. Now I decide to name it Pantsy (for simple reason).

On it's back and mummified. R.I.P., Pantsy. Never suck pants again in your next life.

tick-away

What a name to restart this blog in 2008. My time is really ticking - no manuscript (yet) after almost one year of the completion of Big Tree survey - everything has been just ticking along slowly (ticking over). I need to find the very thing that makes me tick and be productive. The eleventh hour gets a tick for that but it is also unhealthy.

Anyway, productivity aside, I was really ticked off by the way the forest welcomed me back - its very own TICKS, some 50 or so of them! These creatures, albeit tiny, gave me unforgettable love bites that make me wish that I can cut off my limbs! My body is so allergic to their saliva that I couldn't sleep for the past 10 days and need to be on both anti-histamine and steroid cream.

two days after bite, not showing those on arm, tight, hip, and parts rather not mention here

fourth day - one of the itchiest days (actually can't think of which day is not itchy)

day 11 - finally healing, with an accidental scratch scar

Fortunately unlike ticks in the temperate, these tropical ticks are unlikely to be vectors of diseases (e.g. Lyme disease). In every stage of their lifecycle, they just climb up a stem/grass and wait to attach to a passing host, and a meal of fresh blood. The only way to avoid getting their painful (itchy) bites is to avoid physical contact with the shrubs they perched on, or wear pesticide-treated clothes (and get some chronic poisoning at the same time).

I guess the moral of the story is not to walk into the forest if you do not need to (this goes to everyone, whether or not your favorite activity has to do with some letters 'H'). Hopefully ticks do safeguard the seedlings from some human trampling.

Myth or Truth: some people believe that ticks deposit eggs under host's skin when they bite, and the larvae will chomp away tissue after they're hatched, hence the unbearable itch. Think about this - if the ticks are able to inject eggs via their mouthpart (hypostome), they must have had their organs growing in their face, and they must be doing only "oral" sex.

Big Trees alive!

Finally, I'm reviving this blog after almost two years. Mainly because the basic fieldwork of the Big Trees Survey has been completed, and I should start the momentum of writing (besides my regular botany/reading/analyses/software-learning). Also because I really want to say something about our last remaining primary forest to the masses out there.

The survey took almost 2.5 years in the 164-ha BTNR. A total of ca. 140-ha continuous, closed-canopy forest is covered with the 10,200 trees we tagged, measured, mapped, and identified. About 410 morphospecies were recorded, which includes several new records for Singapore as well as BTNR, and numerous rediscovery of extinct species. It's always rather tricky in claiming new records in plants, especially when only sterile specimens are available (herbarium normally takes only fertile specimens, of which records are officially recognised). However, almost all our new records are quite distinctive even in sterile specimens, and certainly I'll work hard to collect, deposit in herbarium, and then report. I also hope that the DNA barcoding of trees will also help me confirm the identification.

This survey is unique and significant in many ways:

• It could possibly be the largest forest tree survey block (not really a plot since it's not square) in the world (one survey in Costa Rica covered 150 ha but only survey six tree species in all size classes, cf. Clark & Clark 1992)


• This complete inventory of all canopy trees not only reveals the actual floristic composition and stand structure of BTNR (suggested in the many great works by Drs. R. Corlett and I. Turner), but also serves as a great tool in understanding the dynamics of a fragmented forest, through long term monitoring (most studies on forest fragments were done in Amazon on many 1-ha or smaller plots, cf. most works by Dr. W. Laurance)


• The map stored in ArcGIS is useful in identifying critical areas for better management and conservation, as well as for collaborative study in the future. Scientists who wish to locate trees of any particular species can extract easily from the GIS database, e.g. Dr. Koichi Kamiya who is now studying the population genetics of Shorea.


• The data will be integrated with the previous two 2-ha Forest Dynamics Plots (FDP) in BTNR, and stored in a relational database (Open Office Base). This HSQL database will then be part of the global CTFS FDP plots database (MySQL).
  

Having said that, still plenty of works ahead.

All BTNR trees bigger than 30 cm in diamater. Cyan dots represents all Shorea spp., one of the main indicator genera of primary forest area

Slow Poke

Some fresh, recently fallen Keruing (Dipterocarpus caudatus ssp. penangianus) fruits were seen along Tiup-tiup path - almost two months after the 'end' of the mass fruting season. Well.. the determination of the timing is really quite ambiguous - nobody did actually scan through all twigs to see if there are any 'leftover'.

Anyway, these fruits are in average smaller than most typical fruits, which calyx tubes are about 2~3 cm in diameter.

Check out the seedlings from the earlier batch, already quite tall! (Late fruits are placed beside the seedling in the top-left and bottom photo for comparison)

So, what actually happened to these late fruits? Why did they fall late? Why are they smaller? Are they as viable as the earlier batch?

Can being late an effective strategy to increase survivability? Perhaps.. Or may be they are just abnormal