Under The Microscope

RICCARTON BUSH: PUTARINGAMOTU. NATURAL HISTORY AND MANAGEMENT, Ed. Brian Molloy; Riccarton Bush Trust, Christchurch, 1995; 330 pp; $39.95

In these days of "user pays" science, with its strong inclination towards "payer says" science when grant application time comes around, this book is a rare treat. It sets out to inform, not necessarily to persuade; to teach but not to preach; to tell things how they are, not how we would wish them to be.

My one substantial quibble is with the title. The book tells of the natural history of the whole flood plain on which Christchurch sits. The Bush focuses the account.

Chapters are contributed by 24 authors, all local experts in their field. Our understanding of the ecology of early Canterbury has been turned topsy-turvy in my lifetime. In the 1950s it was generally believed, following Leonard Cockayne, the father of ecology in New Zealand, that tussock grassland was the "climax" vegetation on the plains. Today, botanists almost universally accept that trees or shrubs, not grass, are the "natural" cover of the region.

While he was still a student, Brian Molloy began digging up, identifying, and dating the charcoals buried in the soil. Against entrenched opposition he was substantially responsible for marshalling the evidence for a new perspective of a vegetation always evolving from grassland or swamp towards forest, following periodic destruction by fire or flood. So it is fitting that Brian, who lives near the Bush, and is a veteran member of the Board of Trustees, should so ably edit the book and contribute to four of its chapters.

The main sections are about the history and effects of human interference; the geology and groundwater, soils and climate; native and introduced plants, with a special chapter by Brian for the kahikatea; the animals; and the management back, as far as possible, to its primeval state. All the chapters are clearly written for easy informative reading. The photographs are excellent.

As a reference book for Christchurch dwellers, it deserves shelf space beside The Guinness Book of Answers. Popular myths to the contrary, I learned that the water in local aquifers has not been depleted since 1905, and that on cold nights Cathedral Square can be 7^oC warmer than Hagley Park.

The biodiversity, as measured by the number of species of conifers and flowering plants, has more than doubled since European settlement. There are fewer natives; some may have been pushed out by adventives. Management changes, such as clearing or drainage of the Bush surrounds, have probably been the knell of others.

The book is a tribute to William and John Deans who set the Bush aside, and to Jane Deans and her successors for persisting in its maintenance as a gift for the future. I recommend it to all interested in the preservation or enhancement of our native vegetation. It should be required reading for professionals.

Pat Palmer is interested in ecological issues.