THE TARARUA REPORT
The Tararua Range and the condition of its vegetative cover are of great economic importance because a large number of rivers that flow through fertile farm lands arise there and because the city of Wellington and many smaller settlements derive their water supplies from catchments within the range. The report by J. T. Holloway and others on the condition of the forests, subalpine-scrub lands, and the alpine grasslands of this range provides scientific evidence of the extensive damage done to our forests by deer and other browsing animals. The following is the synopsis of the report and is reproduced here by permission of the N.Z. Forest Service.
(1) A survey of the forest and related alpine lands of the Tararua Range (384,000 acres) was carried out during the summer 1958-59 by staff of the Forest and Range Experiment Station, the main objective being the determination of the condition of the vegetation, as affected by noxious animals, in relation to rivers control and soil-conservation requirements.
(2) It is emphasised that the Tararua Range is a watershed of such importance (in respect of control of flooding on adjacent lowlands and in respect of the yield of domestic and industrial water) that only one major forest-management objective is permissible—maintenance of the vegetative cover in as nearperfect a condition as possible. All other objectives (recreation, timber production, etc.) must be considered secondary objectives.
(3) It was found that, though much forest remains in fair to good order, serious damage has been done and is being done to highaltitude silver beech forest, to the forest on steep unstable ground at lower elevations, in localities where animals tend to congregate, to the subalpine scrub lands, and to the alpine grasslands.
(4) This has already led to pronounced acceleration of erosion, the lands principally affected being those where the potential for acceleration is greatest. Acceleration of erosion on a far wider scale is probable if control of animals (principally deer and goats) cannot be achieved in, at the most, 5-10 years. (5) With respect to other forest, currently in fair order, the future remains uncertain. These forests have been strongly modified with the elimination of species of pronounced
palatability but there has generally been concurrent spread of unpalatable or browseresistant species. Further change is probable but it cannot yet be determined whether this will be in favourable or unfavourable directions. The effects of continued animal trampling on soil structure, in respect to both the regenerative capacity of the forests and to water-yield characteristics, require careful study.
(6) There is no evidence that past hunting pressure has anywhere been sufficient for reduction of animal numbers to the point where recovery of the vegetation has been possible. Deer numbers have clearly fallen below peak in many areas but this has been due to exhaustion of browse, not to shooting. Instances of so-called “forest recovery” are in all cases instances of the spread of unpalatable or browse-resistant species, a form of “recovery” that would have been experienced even had there never been any shooting at all. (7) As mentioned, goats and deer are the chief agents of damage. The position with respect to opossums remains obscure. Some minor species have been wiped out by opossums and some deaths of forest dominants, attributable to opossums, are locally apparent; but damage done by opossums is largely concealed by the greater damage done by deer and goats. Other animals (pigs, hares, and rabbits) are currently of minor importance.
(8) It is accordingly recommended that vigorous action against deer and goats be taken, the control effort being sustained at least until significant recovery of the highaltitude silver beech forests, subalpine scrub lands and alpine grasslands is apparent. Control of opossums is required in local areas of major damage (by animals of all species in combination) and the opossum position over the remainder of the forests requires careful watching.
(9) The first step towards effective control of deer and goats should be implementation of a hut-building, bridge-construction, and track-formation programme, rendering all affected land readily accessible for hunting. (10) . The survey should be repeated in five years’ time. To assist this reassessment of the position, 82 permanent vegetation sample plots were established during the course of the present survey.
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Bibliographic details
Forest and Bird, Issue 149, 1 August 1963, Page 6
Word Count
707THE TARARUA REPORT Forest and Bird, Issue 149, 1 August 1963, Page 6
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