I was a young patrol officer and it was 1955. I had with me interpreter Laki, police constable Yogoru and two local guides renowned for hunting birds of paradise in the area.

We were walking from our road camp at 2,500 metres to an anomalous, flat grassed area high in the Bismarck Range, part of the central mountainous spine of Papua New Guinea.

We climbed steadily, at first on a track barely discernible to my eyes then hacked our way through thick bush, pushing ever upwards.

The character of the bush suddenly changed, becoming d Denser, darker and danker. We had entered the moss forest. I knew that in the tropics moss forests form at about the 2,800 metre mark, so that’s about how high we were.

My senses were overwhelmed by a confusion of plant life. It took some concentration to ignore the mass and focus on specific varieties. Only then did I see several orchid species, varieties of ginger-like plants, some with spectacular flower stalks, bromeliads - virtually anything capable of surviving in the gloom and constant wetness.

Water dripped everywhere fed by continuous mist and frequent rain. The reason why moss forests develop is the almost constant cloud which totally envelops the forest above 2,800 metres. The micro-droplets of water in the cloud coalesce into larger drops which fall and saturate everything.

The smell is musty and dank with overtones of rot and decay, ever changing from the disruption caused by our slashing bush knives and heavy footfalls. Sometimes a wave of cloying sickly-sweetness would rise from a freshly-cut vine, next moment it might be a foul pungent aroma as we disturbed the decaying mass beneath our feet.

It took me some time to realise we were walking on top of a thick, rotting layer of vegetation. I was warned to place my feet carefully. At one point, Laki, just ahead of me, plunged to his chest as a log he stepped on broke under him. I had no doubt that his cry and torrent of words was eloquent cursing in his own language.

I heard the cursing because I was close to Laki. The sounds were quickly swallowed by the surrounding forest.

But it was the eerie silence of the place which I found most weird. There were no sound-reflective surfaces. No rustle of leaves in this airless place; no sounds of animals or birds; only the quickly absorbed noise of our own progress and occasional conversation.

After half an hour of laborious, high-stepped walking and climbing, I suggested a short break.

“No, kiap, we must not stop. There are a lot of masalais, evil spirits and ghosts in this place. If we stop, they will settle on us like a giant spider web and we will die. We must keep moving.”

So we did.

Another half-hour and the terrain eased, the canopy became lighter and then, between one step and the next, we left the gloom, felt a very welcome breeze, smelled the sweetness of the bush and heard bird calls. The transition was as sudden as it was at the beginning of the moss forest.

Another 10 minutes of easy walking brought us to the edge of a flat, lightly grassed area. We stood in full, warm sunshine. I estimated the area to be about four hectares. A clean, cold creek meandered through it. It was an idyllic scene.

The guides didn’t stop to admire the view. They walked to the creek, stripped off (well, almost; they came from a very modest society), sat in the shallow stream and scrubbed themselves with the fine clean sand. We all followed suit. It was icy cold and welcome.

“We must do this,” they said, through Laki, “it washes off the dirt and smell of the forest and cleanses us in preparation for returning. If we don’t, it makes it easier for the masalais to molest us.”

Constable Yogoru and the two guides built low shelters roofed with big forest leaves and grass while Laki and I walked through the area, dug a pit to take samples of the soil profile for testing by the Agriculture Department and did a rough plane-table survey of the kidney-shaped clearing.

I estimated our altitude at 2,900 metres. All I’d carried with me were two tins of bully beef, extra-thick woollen pants and a jumper. We shared my meat and the kaukau (sweet potato) carried by the others.

That night, bitterly cold, we slept in a thick bed of cut grass under the rough roof sheltering us from the dew. Probably thanks to the day’s exertion, I slept reasonably well.

As soon as it was fully light, we set off for the walk back. We got through the moss forest quickly and without incident. Still the same unsettling weirdness, sights, sounds, smells and pitfalls but it was now somehow familiar,

We moved quickly now, wanting to get back to our camp for a substantial, if late, breakfast.