Mapping Bush Encroachment

You are driving across the farm, scanning the veld, and you get that nagging suspicion that a camp is thickening up. Someone in the passenger seat asks how much, how fast, and where the worst of it is — and the honest answer is a shrug and a vague gesture at a ridge.

That is the problem this discussion sets out to solve. Bush encroachment advances slowly enough that nobody notices from the bakkie until a great deal of grazing has been lost, and you cannot budget against an impression.

It covers how the measurement works — subtract the bare earth model from the surface model and whatever remains is the height of what is growing there — and how that gets divided into height bands and measured in hectares.

Then the practical uses: knowing real carrying capacity rather than assumed, separating browse height from grazing on a game property, pricing and sequencing clearing over several years, and comparing two surveys to prove which blocks improved and which deteriorated.

It is straight about the limits too. Height does not identify species. You see the top of the canopy, not the shrub layer beneath it. And any comparison must be flown at the same time of year, because deciduous bush changes enormously between summer and winter.