Where Natuurmonumenten began its century
In 1913, just a few years after the Society for the Preservation of Natural Monuments was founded, it bought a small parcel of fens and pinewood south of Oisterwijk. The land was being eyed for forestry and drainage; locals petitioned to keep it as it was. That parcel grew, decade by decade, into the reserve you walk through today — roughly a thousand hectares of woodland, heath and water, one of the very first conservation areas anywhere in the country.
That long protection matters more than it sounds. Most Dutch nature has had to be rebuilt over the last fifty years from drained, fertilised, fragmented countryside. Oisterwijk's woods and fens are a rare case of a working landscape that has simply been left alone for a hundred years, and allowed to mature.
How the fens were made
The fens — vennen in Dutch — are the reason people come. There are around eighty across the wider area, ranging from broad open meres like the Voorste Goorven to small bog pools you could almost step across. Most of them were not made by glaciers, and they are not the remains of rivers. They are wind-cut hollows, blown out of the sandy plateau by storms from the south-west long after the last Ice Age. The sand above is permeable; the layer below is not. Once the wind had carved a low spot, rain and groundwater filled it. The Kolkven is the local exception — it was scoured out by the swirling currents of an older river, and is correspondingly deeper and steeper-sided.
The water is dark not because it is dirty but because it is acidic and stained with peat. It supports a specialist plant community: white water lilies, bog asphodel, sundew where the edges are wettest. It is a habitat that has all but vanished from lower Holland, and the reason the reserve is internationally important.
"Wind made the hollows, rain filled them, peat darkened them, and a hundred years of protection has kept them clean."
The leather connection
The forests are a different story. Most of what stands today was planted in the nineteenth century, and the reason was Oisterwijk's tanneries. Brabant leather needed bark — specifically the tannin-rich bark of summer oak — and the tanners grew their own. Oak coppice plantations were cut on a fifteen-year rotation; the bark was stripped, dried, and ground at the Kerkhovense Molen, a wind-powered run mill that still stands on the edge of town. After the bark trade declined the woods were replanted with Scots pine, partly to stabilise drift sand, partly to supply pit-props for the Limburg coal mines.
That mixed industrial history is why a walk through the reserve looks the way it does: long straight ranks of pine, suddenly broken by an old oak coppice with three or four trunks rising from one stump; clearings reclaimed by purple moor grass; a heath that was once an open field. The forest is slowly being shifted back toward a mixed broadleaf canopy, but the bones of the planting are still there if you look.
The signature fens, named
If you walk the 14-Fens trail you'll meet them in sequence. A few are worth knowing by name:
- Voorste Goorven — one of the largest and most photogenic, framed by pine and reed.
- Achterste Goorven — its quieter sister, often glassy at dawn.
- Witven — paler-bottomed than the others, with floating water plants.
- Staalbergven — the swimming fen; sandy entry, supervised in summer.
- Kolkven — the deep one, river-scoured, dramatic in low light.
- Van Esschenven — a smaller wooded pool with floating bog.
What lives here
The reserve is a busy place once you slow down. Red deer and roe deer are both present, more easily seen at dawn and dusk; in autumn the red deer rut and the roar carries across the fens. Kingfishers hunt the stream edges. Great spotted, green and even black woodpeckers all breed here. The fens are alive in summer with dragonflies — keeled skimmer, four-spotted chaser, the spectacular emperor — and at night with bats hunting over the open water. The peripheral heaths support adders, lizards and silver-studded blue butterflies. None of this is curated; the reserve is large enough and old enough that the species mix has settled into something that looks the way Brabant nature would have looked without us.
Visiting the reserve
There are four official Natuurpoorten (Nature Gates) where you can start: Groot Speijck on Van Tienhovenlaan is the main one, with parking, a route board and a forest café. Trails are well-marked with coloured posts — blue for the 14-Fens loop, plus shorter circuits for families. The terrain is flat and most paths are firm enough for hardier mobility scooters and pushchairs, though a few sandier stretches will defeat smaller wheels.
The reserve is open year-round, free to enter, and quietest in early morning and late evening. Dogs are welcome on a lead. The Staalbergven is the only fen where swimming is allowed — and only in summer, when it is supervised. Drones are not allowed anywhere in the reserve, and please keep off the heath even where there is no fence: it is more fragile than it looks.
Where to learn more
Stop in at the visitor centre at Natuurpoort Groot Speijck for paper maps, route booklets and the latest information on closed paths (occasional during ground-nesting season). Natuurmonumenten members get free parking at all the Nature Gates. If you want to go deeper, the society runs guided walks throughout the year, in Dutch and increasingly in English.