13/10/2026
To those interested in agarwood, this is an interesting finding.
The forest may have a
Wood-Wide-Web under the soil, there is also it’s counterpart above ground.
𝗣𝗔𝗜𝗕𝗥𝗜𝗶𝗻𝗳𝗼𝗿𝗺𝘀 | 𝗪𝗛𝗬 𝗪𝗜𝗟𝗗 𝗔𝗚𝗔𝗥𝗪𝗢𝗢𝗗 𝗡𝗘𝗘𝗗𝗦 𝗠𝗢𝗥𝗘 𝗧𝗛𝗔𝗡 𝗔𝗡 𝗔𝗤𝗨𝗜𝗟𝗔𝗥𝗜𝗔 𝗧𝗥𝗘𝗘
-PAIBRI’s working hypothesis on the Dipterocarp Reservoir
Deep in the forest, a will agarwood hunter is not looking for a tree. He is looking for a wound.
He reads trunks the way other people read faces. Old scars where a branch tore away. Bark that healed badly. And the small, dark holes left by boring insects, openings no wider than a pencil lead, which may lead to something remarkable or to nothing at all.
Those holes are not the prize. They are a question.
When an insect bores into Aquilaria, it does more than make a hole. It breaches the tree’s outer defenses and opens a path for microorganisms to enter living wood. If the tree responds, it responds chemically, laying down fragrant resin through the affected tissue as part of its defense. Given years, sometimes decades, that resin accumulates. That is agarwood.
Injury. Living organisms. A tree fighting to survive. The perfume is a wound record.
But the hunter already knows the hard part: insect holes alone guarantee nothing. He will inspect a hundred damaged trunks and cut none of them. This is why finding wild agarwood takes patience, experience, and a reading of the forest’s quiet signals that cannot be taught in a classroom.
At PAIBRI, we think that frustration is a scientific clue.
THE QUESTION NOBODY ASKS
Everyone studies the Aquilaria tree. Almost nobody asks where the microorganisms come from.
In wild primary forest, Aquilaria is sparse and scattered, never a stand, rarely a cluster, often a single tree among hundreds of others. It is not abundant enough to maintain its own permanent reservoir of the fungi that colonize it. So if wounding is the trigger and microbial colonization is the mechanism, something else in that forest must be keeping the microbial pool alive, diverse, and nearby.
Our working hypothesis is that the answer is standing right above the hunter’s head: the dipterocarps.
WHAT THE HUNTERS NOTICED FIRST
This did not begin in a laboratory. It began as a pattern that experienced hunters have been describing for years.
Ask a veteran where he has cut his best material and the answer is almost never a clearing, a roadside, or a young second-growth stand. It is deep forest under closed canopy. And again and again, the account includes a detail that is easy to dismiss as scenery: the resinous Aquilaria was standing beside big dipterocarps. Bagtikan, Yakal, Panau, Apitong, the giants themselves, sometimes within metres of the tree that gave up high-grade resin.
High-grade material keeps turning up in the company of large dipterocarps. Thin, pale, low-yield wood keeps turning up where those giants are already gone.
We are careful about what that does and does not mean. A field correlation can have several ordinary explanations. Old forest is simply older, less disturbed, less picked over, and its trees have had more decades in which to accumulate resin. The presence of dipterocarps may be a marker of forest age rather than a cause of resin quality.
But the pattern is consistent across too many hunters, too many provinces, and too many separate accounts to leave unexamined. An observation repeated that often deserves a mechanism, not a shrug. We propose three.
ONE. THE MICROCLIMATE HOST
Large dipterocarps build the room before anything can live in it.
A closed dipterocarp canopy holds humidity, buffers temperature swings, blocks direct sun, and drops a continuous rain of leaf litter, twigs, fruit and bark onto the forest floor. That is the substrate on which saprophytic and endophytic microfungi live between hosts. Remove the canopy and you do not merely lose shade. You lose the moisture regime and the organic input that keep the inoculum bank viable.
A lone Aquilaria in an open field is wounded in a desert, microbiologically speaking. The same wound in a closed-canopy forest is wounded inside a living culture collection.
This is also the simplest reading of what the hunters report. A tree standing beside a dipterocarp giant is a tree standing inside the right room.
TWO. INSECT VECTORS
A spore on bark is harmless. A spore in the xylem is an event.
Wood-boring insects are the delivery system that crosses that boundary. Aquilaria has documented borers of its own, including the beehole borer, Neurozerra conferta, formerly Zeuzera conferta, recorded tunnelling in Aquilaria malaccensis. Ambrosia beetles are the more intriguing candidate, because they do not simply carry fungi incidentally. They farm them, maintaining fungal gardens in their galleries and transporting partner strains in specialised pouches.
That link is not merely plausible. Among the Fusarium species reported from agarwood is Fusarium ambrosium, a fungus named for its association with ambrosia beetles.
Dipterocarp forests support large and varied borer populations. Those insects move through the canopy and the understorey, and when one of them drills into an Aquilaria trunk it does two things at once. It injures the tree, and it inoculates the injury.
THREE. LATENT PATHOGENICITY
Here is the part that explains the hunter’s hundred empty trunks.
Many of these fungi are already inside healthy Aquilaria, living quietly as endophytes and causing no disease at all. They are passengers, not invaders. What changes is the tree’s condition, not the fungus’s presence.
When the tree is pushed into severe physical stress, whether by deep wounding, storm damage, root disturbance, drought or repeated insect attack, the balance tips. The endophyte begins to behave as a pathogen. Tissue is colonised. The tree escalates its chemical defense, and sesquiterpenes and chromones appear in wood where healthy tissue has none.
This is why insect holes are not a promise. The hole is an entry point. The resin requires a tree whose defenses have been engaged hard enough and long enough to respond at scale. Most wounded trees never reach that threshold.
One point deserves precision. The proximate switch for resin synthesis is the tree’s own signalling. In controlled work, crude fungal extract alone failed to induce sesquiterpene production in Aquilaria shoot culture, while methyl jasmonate, a plant stress hormone, succeeded. The fungus appears to be the provocation. The tree is the chemist.
THE SCIENCE BEHIND THE RESERVOIR
Dipterocarps are not ordinary tropical trees. Most tropical trees form arbuscular mycorrhizal partnerships. The Dipterocarpaceae are overwhelmingly ectomycorrhizal. In one Bornean study, putative ectomycorrhizal Basidiomycota were found in 85 percent of dipterocarp root samples against 45 percent for non-dipterocarp hosts, with Thelephoraceae alone appearing in 54 percent of dipterocarp roots against 9 percent of the rest.
This means the canopy giants in the photograph sit on top of an enormous subterranean fungal infrastructure. Kilometres of hyphae in a handful of soil. A permanent, carbon-fed, biologically active matrix running through the entire forest floor.
We want to be exact about our claim. We are not saying that these ectomycorrhizal fungi produce agarwood. They do not. The fungi repeatedly recovered from resinous Aquilaria wood are a different group entirely: Ascomycetes such as Fusarium, Lasiodiplodia, Botryosphaeria, Chaetomium, Acremonium and Epicoccum, living as endophytes or saprophytes.
What we are saying is that the dipterocarp-driven system creates and sustains the conditions in which that Ascomycete community persists at high diversity and high activity. The giants do not make the resin. They keep alive the world that makes the resin possible.
WHY THIS MATTERS FOR PHILIPPINE PLANTATIONS
If the Dipterocarp Reservoir Hypothesis holds, a conclusion follows that the industry has largely ignored.
You cannot replicate wild-grade agarwood by replicating the Aquilaria tree alone. A sterile monoculture on cleared land has the host and none of the system. No canopy buffer, no litter-fed inoculum bank, no vector traffic, no soil matrix. Everything must be supplied artificially, and supplied forever.
It also reframes native dipterocarp conservation. Protecting Bagtikan, Yakal Malibato and Panau is not only a biodiversity obligation. It may be infrastructure for the resin economy itself.
WHAT WOULD PROVE US WRONG
We hold this as a hypothesis, not a finding, and we will say so plainly.
It predicts testable things. That Aquilaria growing within intact dipterocarp forest carries a richer and more active endophyte community than Aquilaria in open plantation. That agarwood-associated Ascomycetes can be recovered from dipterocarp litter and rhizosphere soil. That borer species moving between the two tree groups carry overlapping fungal loads. And that if hunters’ finds were recorded systematically, with location, canopy composition and resin grade, the association they describe would either hold up under counting or disappear under it.
If those tests fail, the hypothesis fails. We would rather publish that than defend a comfortable story.
ONE LAST WORD FOR THE HUNTERS
Every mechanism above was noticed first by men with bolos and no microscopes, who learned to read bark, borer holes, canopy and the smell of a cut. The observation that the best resin stands in the shadow of giants is theirs, not ours. Field knowledge came decades before the literature.
Our work is to test it, measure it, and give it a name.
The forest has been running this experiment for millions of years. We are only just learning to read the notes.
Philippine Agarwood Inoculation and Bioproducts Research Inc.
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