It is not considered that the military use of the area over the last 100 years has affected it one way or another. Although Zone 1 has been and still is used as an impact area for artillery, bombs and rockets, and is a manoeuvre area for armoured vehicles ranging from 17 tonnes (NZLAV) to 50 tons (Centurion) it does not appear any different visually from the adjacent section of the dune field that lies within Tongariro National Park. The theory is that the whole area i.e. the surface, is so unstable anyway that the impacts of shells and vehicles is actually negligible compared to the effects of wind and rain, snow and ice.

Because the dunes are constantly changing it is very difficult to measure their age. This is complicated in Zone 1 because the very real risk of buried unexploded munitions prevents digging and core-sampling. One of the recent studies found that the best way to tell the age of a dune is by measuring the age of the vegetation on it…

Some of the more mature trees in the dune field although only 3-4 metres high, and 3-400 years old

The event that has had the most impact on the Rangipo area was the Taupo eruption some time between 182 and 250AD. It is not really known what this area was like before this eruption but it was certainly scoured clear of vegetation as a result. Since that event, man-made fire has probably been the biggest impactor on the state of the dune field, with periodic large lahars, on average about every 500 years or so, having the next most impact.

The dunefield is slowly expanding north and no one is quite sure why …

The dune field is a rugged challenging one for plant life and there is a clear succession that starts with growths like this…

…around which the sand drifts and builds up. simple grasses like bristle tussock may then develop followed slowly, often over years or decades by more complex vegetation.

It is a harsh unforgiving process…as dunes the surface is constantly shifting: the risk to developing vegetation is that it may be simply buried under the shifting sands, or have the sand around it uncut, exposing its roots…

…either way not good for ongoing survival…

Even though there are substantial beech forests only a few kilometres away, the beech forest will probably not regenerate in the dune field because a fungus necessary to its growth is not in the soil there and is very difficult – read, close to impossible – to establish artificially.

The desired future for the Rangipo dune field is for it to regenerate naturally i.e. to its pre-settlement state. Replanting is not considered necessary, more a tool of last resort and it is considered of greater benefit to focus conservation efforts on the control of invasive weeds and pest animals like deer, rabbits, hares and possums.

The Army conducts its own pest control programmes across the Training Area, all 63,000 hectares of it, targeting pests like possums, rabbits and hares, and invasive weeds like the various forms of weed pines. Because the Area has an 85% usage rate – there were only three days this month in which we were able to get into Zone 1 for this study trip – and due to the number of hazards on and under the ground, much of this work is done by helicopter. As a part of this programme, the Army is also investigating source vectors for invasive weeds and sharing the results of this work.

Smoko and networking

The road home…

In another life, I trudged all over the dunes ‘by day and by night, regardless of season, weather or terrain’…environmentally then, my main concern was the fine grit that, when wet, would stick to everything…one particle being all it took to convert rifle into not much more than a blunt instrument…none of us back then had any notion of the rarity, vulnerability or real harshness of this unique environment…I’m glad of this one last wander in my old stamping grounds…