page 70

Book Reviews
Vegetation Map of Tongariro National Park, 1:50,000

I. A. E. Atkinson, 1981. N.Z.D.S.I.R. (N.Z. Government Printer $4.50)

In Tongariro Natonal Park, so much at risk from invading exotic plants, it is a saddening exercise to compare Dr Atkinson's map of field work of the sixties, with the present extension of the introduced Calluna vulgaris, the heather. It has advanced even further into the red tussock, on the north of the Park, dulling the dominant colour of the Central North Island high country. And on the southeast, despite a continuing battle, Pinus contorta has continued its spread from nearby Forest Service plantations.

These two examples show a little of the dynamism of landscape and vegetation in Tongariro National Park. Far older in origin are the patterns of variation in forest cover so well shown by Dr Atkinson's map. As the destructive effects of the Taupo pumice shower of 1860 years B.P. decrease from north to south, so do the patterns of forest reinvasion show so clearly on the vegetation map.

The map standard is high, and backed by patient and difficult traverses through vegetation, from the most tangled bush, to windswept, dry stonefields. Appearing as it does, when extensive vegetation mapping is in rennaissance in New Zealand, the techniques, interpretation and presentation are models worth following by mapping agencies. The accompanying booklet is intended for popular use; but the standard of botanical and landform notes render it equally useful to planner, researcher and teacher.

However, the dynamism of the Tongariro National Park's vegetation, well described in individual sections, is a theme that could well have been extracted and stressed in a single page. Few alpine areas in New Zealand show the interaction between plant and unstable soil as well as the “desert east of Ruapehu, and the Tongariro National Park shows a wide transect of the local, volcanic and Taupo pumice effects on forest, from maximum influence on Tongariro to zero influence at Ohakune. This trasect is now enhanced by the recent and unmapped addition on Mt. Pihanga.

The treatment of geology is good, and well summarises recent knowledge but Dr Atkinson's treatment of the ash shower soils could have been improved by noting the importance of the pre-Taupo eruption, finer-textured ash showers as drainage impedance layers. The presence of these showers does play an important role in vegetation pattern in the higher rainfall parts of the Park. And, (p. 4), the “desert zone of SE Ruapehu extends over a far bigger area than the Whangaehu outwash plain.

The description of the vegetation is done by a brief and clearly coded floristic/physiognomic classification, accompanied by good profile diagrams. Added are notes on birds, and useful comments about human movement through some of the denser types of woody vegetation. Despite the criticisms above, the booklet is appealing in its compactness, wealth of detail and clear presentation, and is recommended, with the map, to all trampers, naturalists and ecologists.