A force-directed view of every relationship described below — trees (dark), mycorrhizal partners (orange), pathogens (red), saprotrophs (purple), lichens (lime), and the environmental factors the lichens read. Drag any node. Hover for details. Toggle categories on/off below.
Outside-of-the-Bos factors (Schiphol, the A9/A10, regional livestock NH₃) connect to the same lichen species you'd find on a tree-trunk inside the forest. The graph is the bridge.
Eight of the ten most-observed fungi in the Amsterdamse Bos are wood-decomposers. The list reads less like a mycological census than like an inventory of dead wood.V
| Obs. | Species | Role | Substrate |
|---|---|---|---|
| 588 | Trametes versicolor · TurkeytailV | Saprotroph (bracket) | Dead hardwood — oak, beech |
| 435 | Hypholoma fasciculare · Sulphur tuft | Saprotroph (gilled) | Stumps, fallen logs |
| 372 | Coprinellus disseminatus · Fairy inkcap | Saprotroph | Rotting stumps |
| 371 | Trametes gibbosa · Lumpy bracket | Saprotroph (bracket) | Dead beech |
| 365 | Daldinia concentrica · King Alfred's cakes | Saprotroph | Dead ash, dead birch |
| 359 | Ganoderma lipsiense | Saprotroph (bracket) | Old standing hardwood |
| 352 | Polyporus squamosus · Dryad's saddle | Saprotroph | Dying / dead deciduous |
| 295 | Auricularia auricula-judae · Jelly ear | Saprotroph | Elder + dead deciduous |
| 284 | Piptoporus betulinus · Birch polypore | Saprotroph (bracket) | Dead birch — host-specific |
| 253 | Xylaria hypoxylon · Candlesnuff | Saprotroph | Dead wood + stumps |
| 196 | Fomes fomentarius · Hoof fungus | Saprotroph (bracket) | Standing dead hardwood |
This is what a forest looks like once it is old enough to die honestly. The 1934–1970 plantings have entered the phase where standing and lying deadwood accumulates faster than it disappears. The bracket fungi — Trametes versicolor at the top, Ganoderma, Polyporus, Piptoporus, Fomes — are the visible part of that turnover. The forest's most-recorded mycology is its compost layer.
A 1980-era Bos would not show this list. The dead-wood guild only begins to assemble once a planted forest crosses the threshold where its first cohorts produce serious mortality. The graph timestamps that threshold somewhere around 2005, when Armillaria mellea first appeared. The list above is what's been accumulating since.V
Beneath the visible canopy runs a parallel forest of ectomycorrhizal exchange. The graph carries 25 partner-of edges between fungi and trees. They cluster around four hosts — and the partners barely overlap.V
Oak is the centre of the underground network — more than twice the partners of anything else. Beech is the secondary hub. Birch runs a small parallel ecosystem with its own specialists, headed by Amanita muscaria (the iconic red-and-white vliegenzwam, 62 observations across the Bos). Boletus edulis appears under both oak and beech; Amanita muscaria also partners with pine. Otherwise the host-segregation is near-total.
One fungus, one tree, one hill: Tricholomopsis rutilans (Koningsmantel) is recorded in the Bos exclusively at De Heuvel, which contains the forest's only stand of Corsican pine — the fungus's obligate host. Every Koningsmantel observation in the entire dataset clusters there.
Pathogens are how the underground partnership ends and the dead-wood economy begins. The graph carries three such edges, and one of them is the bridge between layer two and layer three.
| Pathogen | Obs. | Host | Host obs. | Reading |
|---|---|---|---|---|
| Armillaria mellea · honingzwam | 101 | Quercus robur | 89 | Parasitises living oak, then continues as saprotroph in the dead wood it produced. |
| Heterobasidion annosum · dennenmoorder | 32 | Pinus sylvestris | 8 | Conifer root-rot. Pathogen observations outnumber host — the rot is being logged through its effect. |
| Rhytisma acerinum · inktvlekkenziekteV | 39 | Acer pseudoplatanus | 204 | Black tar-spots on sycamore leaves. A biosemiotic sign — the fungus the leaf wears. |
The Armillaria switch. The same organism is the mycorrhizal partner of Quercus robur and its eventual killer. After the kill it does not leave — it continues to live in the standing and lying dead wood, now as a bracket-fungus saprotroph. One species rotates through all three layers of this story.V
The numbers in the second row are quietly diagnostic. The conifer pathogen Heterobasidion annosum has more observations than its host: 32 vs 8. People are not logging the rot directly — they're logging dying pines and the fungus they find on them. The pathogen has become more recordable than the tree.V
A lichen flora is a slow-motion air-quality station. The Bos's reads, today, as "high regional nitrogen deposition, no recovery signal yet."V
| Obs. | Species | What the graph tags it as |
|---|---|---|
| 125 | Xanthoria parietina · groot dooiermosV | NH₃-high indicator — the orange nitrophyte on every Bos tree |
| 71 | Lecidella elaeochroma | Pollution-tolerant |
| 67 | Ramalina farinacea | Moderate N-tolerant fruticose |
| 66 | Phlyctis argena · whitewash lichen | Acidic bark, moderate pollution |
| 65 | Flavoparmelia caperata | Moderate-tolerance shield |
| 62 | Physcia adscendens | NH₃-high indicator |
| 52 | Parmelia sulcata | N-tolerant |
| 47 | Parmotrema perlatum | Moderate tolerance |
| 41 | Cladonia fimbriata · trumpet lichen | Terricolous, peat & bark |
| 35 | Evernia prunastri · eikenmosV | NH₃-low recovery indicator |
| 27 | Physconia grisea | Best NH₃ indicator (Frati 2007) |
| 27 | Candelaria concolor · candleflame | Nitrogen-tolerant |
Six nitrophytes against one recovery indicator. The species the graph tags as NH₃-high (Xanthoria parietina, Physcia adscendens, Physcia tenella, Physconia grisea, Phaeophyscia orbicularis, Hyperphyscia adglutinata) all flourish. The single species that would signal recovery — Evernia prunastri, oakmoss — sits at 35 observations, less than a third of Xanthoria.V
The clean-air bellwethers — Usnea spp., Lobaria pulmonaria, Hypogymnia physodes — have zero records in the polygon.V
This is consistent with the geography: Schiphol sits ~5 km north of the Bos, the A9 runs along its southern edge, and the A10 frames the city behind it. The Bos's lichen flora is reading those sources accurately, in slow motion — its dominance pattern matches what would be predicted by the regional NO₂/NH₃ deposition maps from RIVM.
computing…
A graph of when in the year these fungi were spotted is not a graph of when fungi fruit. It is a graph of when people walk the Bos looking for them.
The bars are the observation curve. The dashed lime line is an estimate of when the fungi actually fruit, projected onto the same 19,531-record total — averaged from European temperate-forest mycology phenology (Boddy & Heilmann-Clausen 2008; KNNV NL Paddenstoelenwerkgroep summary).V
The curve is not bell-shaped. It is a near-vertical spike in autumn. October alone accounts for 40 % of the entire dataset — against a biologically estimated ~18 %. September → October → November together: 68 % observed vs ~45 % expected. June bottoms out at 1.3 % observed, against ~5 % expected.
The shape of the gap is the project's central biosemiotic finding: this is not the forest's biology. It is the calendar of human attention. The mycology clubs run their forays in October. KNNV's Paddenstoelenwerkgroep schedules its excursions in autumn. Foragers walk after the first rains. waarneming.nl sees the resulting upload spike. Fungi that fruit briefly in May, or that persist year-round on bark, are equally present in the forest — but observers aren't there to log them.
Lichens spike in February (453) and November (510) — precisely when fungi are scarce. The same observers walk the same paths, but pivot their attention to whatever the bark is wearing rather than what is fruiting beneath. The August trough at 13 records is the year's quietest moment: observers are chasing summer fungi, not staring at lichen.
Two graphs of the same forest, the same network of observers, one running inversely to the other. The fungi calendar peaks where the lichen calendar troughs and vice versa. The forest is being read at every month of the year — but never by the same kind of looking at once.
Trees host three biological systems at once. The Bos's fungi and lichens make all three readable in the same dataset.V
The pathogens are the rotating door between layer two and layer three. Armillaria mellea lives off an oak's roots, kills it, then becomes the bracket on its stump. The same organism crosses the boundary.
It is fully into its decomposition phase — the inventory leads with bracket fungi, not pioneer species.
Its underground mycorrhizal network is healthy and host-segregated, with oak as the centre.
Its above-ground air quality is poor, and the lichen flora reads it accurately — high-N indicators outnumber recovery indicators ~6:1.
The dead-wood economy is now self-sustaining but only recently. A 1980-era Bos would not show this list.
Every reading on this page comes either from citizen-science records (the species lists) or from sensors at the bos perimeter (the live air-quality post, ~600 m from the southern edge). The agent has no measurement inside the canopy itself.
A small in-canopy sensor stack — particulate, NO₂, CO₂, humidity — mounted somewhere in the interior of the bos would be the next honest step. It would let the agent compare what the air does at the edge with what the trees actually breathe, and would close the loop between the perimeter station and the lichen layer. Hardware exists for ~€300–500; what's missing is a host site, a power feed, and permission. Marked here as a future, not a promise.