MANAGING FOR THE LONG TERM

Forest and Bird, Volume 19, Issue 2, 1 May 1988, Page 32

MANAGING FOR THE LONG TERM

Although considerable progress has been made in developing a network of reserves! in New Zealand during the last decade, significant deficiencies still occur. However, it is important that areas already protected are not ignored; reservation is only the beginning, not the end-point for conservation. In this article Dr David Norton of Canterbury University’s School of Forestry discusses some of the issues involved in the ecological management of reserves. S ome reserves are large (for example national parks) and, with the exception of some grassland and wetland areas, are unlikely to suffer directly from human impact in the near future. However, deer, goats, possums and other introduced animals threaten even the most remote areas, while climatic changes associated with the global increase in CO2 will also affect them. Most other reserves are small, especially in the more intensively developed parts of New Zealand (see figure one). These need scientifically-based management if they are to survive with most of their natural values intact. We should now be building on the ecological management already underway to ensure the long-term survival of all our reserves.

Why manage?

There appears to be much confusion over what is meant by managing reserves. Often this is seen as involving some form of exploitation, such as logging, but in fact that is only one type of management and others such as conservation management are essential. Management can be divided into two broad categories: the ‘‘do nothing" or passive management approach, and the active intervention approach. In national parks, larger scenic reserves and ecological areas, the ‘‘do nothing" approach is undoubtedly most appropriate, with a few qualifications — introduced animal control, recreation planning, and monitoring come to mind. Smaller reserves or those containing sensitive communities like grasslands and wetlands will require the active management approach if the threatened species and communities they contain are to survive. Is there any value in having small reserves? Some may doubt their value, but these small refuges may house the only examples of plants and animals formerly widespread in an area and are therefore of considerable scientific interest. For exam-

ple, two reserves totalling 4.9 hectares are all that remain of the grasslands and shrublands of the Canterbury Plains (once 300,000 ha in extent!) There are two main reasons for active management. First, because they are often small and isolated (perhaps surrounded by farms), reserves are very vulnerable to windthrow and fire.? It is often difficult for a full range of native species to re-establish after disturbance in small reserves, either because there is too much competition from introduced plants or because there is no seed source left. Although many disturbances are caused by humans, some occur naturally. Windthrow has created havoc in some areas, while the death of adult kKaikawaka on Banks Peninsula probably resulted from natural causes. Nevertheless, small reserves often do not recover after they have been naturally disturbed because humans have eliminated the plants that would normally invade after disturbance or have introduced plants from outside New Zealand that take their place. One of the features of small reserves is that they mostly contain mature plant communities; disturbed or seral communities are poorly represented. Secondly, we may need to actively manage when reserves contain vegetation that

is changing. Perhaps the best examples are grasslands which are developing into shrublands. In many instances these grasslands have been maintained for tens or even hundreds of years by fire and/or grazing. Because these areas were protected for their grassland values, continued grazing or managed fire may be necessary to maintain them. Similarly, open pakihi in North Westland with its distinctive plants and the habitat it

provides for fernbirds and bitterns is undergoing change to forest. These pakihi have formed after fire and logging and without further fire will lose many of their present values as they revert back to forest. We can draw parallels with other countries: for example, scots pine and birch invasion of East Anglican heathlands. In North America and particularly Europe, active intervention is commonly used to conserve semi-natural areas. Chalk grassland and acid heathlands are grazed and deciduous woodlands are coppiced. Although many of the pressures affecting New Zealand reserves are different, active intervention is still likely to play an important role in conservation management here. Of course, ecological management is not new in New Zealand. In the 1890s Richard Henry was transferring kakapo and kiwi to Resolution Island. Other rare birds such as the black robin and takahe have long been managed, as have plants such as the Castle Hill buttercup and Hebe armstrongii. On islands such as Tiritiri Matangi and Mana, revegetation programmes are taking place. Urban reserves such as Riccarton Bush in Christchurch have been intensively managed. However, in many reserves, management has been minimal and largely passive. Where it has been active, it has been related to saving single species rather than whole communities of plants or animals. However, if we are to retain the full range of ecological values in reserves, we will have to manage communities too.

How do we manage?

First, we must have a good knowledge of the ecology of the species or communities concerned. That means monitoring, with an initial census of what is present and a longer term study of the losses and gains of both vulnerable species and of potentially aggressive invaders. Prior to management, it is necessary to clearly identify the important ecological values and the threats that face them. In some cases this may be difficult. For example, shrubs readily invade induced grassland when fire or grazing ceases, but often the grassland is felt to have the greater ecological value. However, it can also be argued that management should aim to re-estab-lish the ‘‘natural’’ vegetation at the site. Clearly issues of this type need to be resolved before any management is undertaken. Active intervention management can include a large number of options: transplanting to increase plant numbers or lost plants, removal or modification of other plants (eg. introduced plants or vigorously regenerating native plants like mahoe or wineberry), and environmental manipulation through deliberate disturbance (eg. fire and grazing), to list but a few. In some instances there may be no change from the kind of management that existed before the area was reserved. For example, in the South Island high country, continued grazing may be the most appropriate management strategy. We also need to consider management of areas adjacent to reserves (buffer zones), for example, to prevent fertiliser or seed drift, introduced plant invasion or altered

water tables. There are always pluses and minuses when intervening in nature. Fire may help maintain grassland vegetation but reduce insect numbers. There are risks when transplanting through mixing genetically different populations. So, for example, it has been recommended that plant material used for revegetating Mana Island comes only from the Sounds-Wellington ecological region, and preferably from Mana Island itself. Finally, when establishing reserves, we should think about how easily they can be managed as well as biological diversity and representativeness. It may be simpler to have one large reserve rather than two smaller ones, even if this means that certain plant and animal communities are not represented in reserves in each ecological district.

Conclusions

Many people have fought long and hard for the reserves we now have in New Zealand. If the values that these reserves were established for are not to be lost, it is essential that we do not view reservation as the end of the conservation effort, but rather as the beginning. We must work together, conservationists, land manager and scientists, and continue the work already started to achieve effective ecological management of all our reserved areas in order to ensure their long-term survival. ! — Reserve is used in a colloquial sense in this article to refer to national parks, scenic reserves, ecological areas and other protected natural areas. ?- Although natural disturbance is a normal feature of native plant communities Acknowledgements I would like to thank David Given, Colin Meurk, Brian Molloy, Colin Ogle and Susan Timmins for valuable discussion on the issues raised in this article.

Further Information Kelly, G C and Park, GN (eds). 1986. The New Zealand Protected Natural Areas programme. A Scientific Focus. D.S.1.R Wellington Mark, A F 1985. The botanical component of conservation in New Zealand. New Zealand Journal of Botany 23, 789-810. Meurk, D C 1987. Conservation objectives in pastoralism. Proceedings of the New Zealand Grassland Association 48, 71-74. Molloy, B PJ 1971. Possibilities and problems for nature conservation in a closely settled area. Proceedings of the New Zealand Ecological Society 18, 25-37. O'Connor, K F. 1982. The implications of past exploitation and current developments to the conservation of South Island tussock grasslands. New Zealand Journal of Ecology 5, 97-107. Ogle, C C 1987. The incidence and conservation of animal and plant species in remnants of native vegetation in New Zealand. In D A Saunders, G W. Arnold, A A. Burbidge and A J M Hopkins (eds), Nature Conservation: The Role of Remnants of Native Vegetation. Surrey Betty and Sons Ltd, Chipping-Norton, NSW pp 79-87. Scott, D. 1979. Use and conservation of New Zealand native grasslands in 2079. New Zealand Journal of Ecology 2, 71-75. Timmins, S M, Atkinson, I A E and Ogle, C C. 1987. Conservation opportunities on a highly modified island. Mana Island, Wellington, New Zealand. New Zealand Journal of Ecology 10, 5765. he New Zealand Ecological Society is running a three-day symposium on ‘‘Management of New Zealand's Natural Estate’’ in Dunedin on August 22-26. Managers and scientists will speak on a number of issues related to this theme. Anyone may attend. Further information: The Secretary, NZ Ecological Society, PO Box 12019, Wellington.

mall reserves are a common feature of the more intensively developed parts of New Zealand. The following table is based on the ‘‘Biological Survey of Reserves Series’’ and presents the mean area and size distribution of scenic reserves in nine regions of New Zealand. Historical reserves and domains have not been included in the analysis, unless they have high biological values. Some reserves which consist of two or more discrete units have been split for analysis. In several areas (eg. north Westland) the analysis did not include new reserves created since the survey data was published.

Table 1

These data show that the mean size of scenic reserves varies considerably, primarily with respect to development. The two areas with the smallest mean reserve sizes, north Auckland and west Taranaki, are major urban/farming and farming areas respectively, while the two areas with the largest mean reserve sizes, south Westland and Marlborough Sounds, have only limited urban and rural development. The size distribution of reserves also follows this pattern with 60 percent of the west Taranaki reserves less than 10 ha compared with only 6 percent in south Westland. For the 439 reserves analysed, 27 percent (119) are less than 10 ha and 54 percent (240) less than 50 ha. Clearly small reserves are a common feature of the New Zealand protected natural area system. Some of the data presented above conceal the extent of small reserves in the more intensively developed parts of New Zealand as some of the geographical districts analysed are very diverse (eg. Canterbury and Otago).

Table 2

The relationship between development and reserve size (and number) is very dramatically shown with only three reserves (2.3, 2.6, 11.4 ha) present on the intensively farmed Canterbury Plains (500,000 ha). Banks Peninsula, an area that has experienced considerable human impact since the first European settlers, has 43 percent of reserves less than 10 ha and 90 percent less than 50 ha. The remainder of Canterbury (high country and north Canterbury) has on average much larger reserves; only 7 percent of the reserves are less than 10 ha. When early botanists such as Laing and Cockayne visited Banks Peninsula at the turn of the century the forests were already severely fragmented as a result of fire and logging over the previous 50 years. At this time kaikawaka was a distinctive and common tree in the uppermost forest remnants, usually growing in association with thinbarked totara. However, by the time Kelly surveyed the scenic reserves of Banks Peninsula in the late 1960s, kaikawaka was all but extinct. Widespread mortality appears to have occurred amongst adult trees in the 1940s and 1950s with only one adult and a few small areas of regenerating saplings present. This mortality has occurred irrespective of the size of the forest remnants and irrespective of whether or not they were protected. Research is presently underway to establish the cause of the mortality.

A further set-back for kaikawaka occurred in June 1984 when a gorse fire on the Akaroa side of Flag Peak was swept out of control by gusty northwest winds over the top of Flag Peak and down into Armstrong Scenic Reserve. About 400 kaikawaka saplings were killed by the fire representing a 75 percent reduction in the total kaikawaka population on Banks Peninsula. This area had until then been considered as offering the best chance for the long-term survival of this species on Banks Peninsula. Today there are about 145 kaikawaka distributed between seven sites of which 75 percent occur at just two sites; about 30 percent of all kaikawaka are in poor health. On Banks Peninsula kaikawaka has come close to extinction as a result of both natu-

ral and human-induced disturbance over the last 50 years. This has occurred despite many of the best kaikawaka sites being in scenic reserves. The fate of this species clearly illustrates the vulnerability of small reserves. Without some form of management there is a strong likelihood that kaikawaka could become extinct on Banks Peninsula as have other species (eg. hinau and rimu. Two male rimu exist but no female trees are known). It is also worth noting that with the death of the adult kaikawaka, we have also lost the very distinctive filmy fern Hymenophyllum malingii, which usually occurs abundantly as an epiphyte on mature kaikawaka. This fern has not been seen on Banks Peninsula since the early part of this century. #

mean reserve area (all reserves) (reserves % reserves in different size classes (ha) 1000ha) N ha n ha 10 10-50 50-100 100- >1000 1000 S. Westland 322 S48 29 264 6 16 13 56 9 Marlborough Sounds 85 509 11 ee 21 11 14 45 9 S. Marlborough 232 20 47 4 41 8 iis! 17 N. Westland 27.506 26 174 26 ¥ 15 33 4 Canterbury 727. 196 71 50 31 47 7 14 l Otago 53° 167 52 Eas 17 2 13 43 2 E. Taranaki lo 166 yg eres se 21 30 15 31 at N. Auckland ao ©) 33 33 50 30 12 6 0 W. Taranaki 40 30 40 30 60 30 5 5 ) TOTAL 439 260 419 116 27 Puff 12 28 5

TABLE 1: RESERVE SIZES FOR NINE REGIONS OF NEW ZEALAND

mean reserve area (all reserves) (reserves 1000ha) N ha n ha Plains =) 5 2 5 Banks Peninsula 42 28 42 28 Rest of Canterbury OF 2 479 26 90 % reserves in different size classes (ha) 10 10-50 50-100 100- > 1000 1000 66 33 0 0 0 43 48 2 fi 0 7 48 15 26 4

TABLE 2: RESERVE SIZES FOR THE CANTERBURY LAND DISTRICT