PARKS AND GRAZING

Forest and Bird, Volume 23, Issue 2, 1 May 1992, Page 33

PARKS AND GRAZING

bes ees! Report by Senior

MIKE HARDING,

Ranger B. Ahem,

Visitors in national parks in the South Island, or one of many other protected areas, will often be greeted by the incongruous sight of farm animals among the forests, wetlands and tussock grasslands of the backcountry. Unrestrained, and usually with the approval of the Department of Conservation, they graze with little assessment being done of their environmental impact. The integrity of these major protected natural areas is threatened, says

and these

unique remnant slices of natural New Zealand are being slowly transformed into examples of an English country park.

ROPPED PASTURE and muddy stock-trampled tracks are familiar images of the grazing lands that dominate the New Zealand countryside. However, the herds of curious cattle or straggling mobs of sheep that are a common sight from our country roads are not confined to farm paddocks. Over 114,000 hectares of conservation lands are grazed with impunity by domestic stock. And that does not include over 4,000 hectares of grazing licences within national parks or the many cases of trespassing stock. Each winter, at Mavora

Lakes Park in northern Southland, some 600 cattle graze dense red tussock grasslands — the best protected remnant of the extensive native grasslands that once covered the Southland plains. Wading into bogs and streams, they wallow in the water that feeds the Mararoa River — one of the country’s best-known trout streams. Alongside the scenic Milford highway hundreds of sheep graze the grassy flats of the Eglinton Valley within Fiordland National Park, surrounded by the towering peaks of this prestigious World Heritage Area. Straying freely into the tall red and silver beech forest, they browse young seedlings and inhibit forest regeneration. And each autumn cattle trample their way through the magnificent beech forests of Mt Aspiring National Park to spend the winter grazing the grassy flats of the Dart, Wilkin and Siberia valleys. At the entrance to Mt Cook National Park, one of the country’s key tourist attractions, sheep graze the Birch Hill flats, a rare area of eastern montane grassland within a national park. Why are these destructive animals allowed to graze in areas set aside for nature conservation and specifically for the strict protection of the indigenous flora and fauna? Several arguments have been put forward: historic nghts to grazing; reduced fire risk; the impracticality of fencing; the economic viability of adjoining farms; weed control; the maintenance of grassland conservation values; and even the contention that browsing mammals replicate the role of extinct native avifauna, such as the moa. Somewhere in the debate it appears to have been forgotten that the public conservation estate contains only the battered remnants of a unique indigenous flora and fauna. Surely grazing can only be justified in national parks and reserves if it directly assists in maintaining conservation values, such as the light grazing of some tussock grasslands. New Zealand’s flora and fauna evolved over millions of years in the absence of browsing mammals. Introduced wild animals have had a devastating impact on palatable native plants, slowly

PARKS AND GRAZING

transforming forest, shrubland and grassland ecosystems and threatening native bird and insect populations. Domestic stock have a similar impact except that they are concentrated on valley floor grasslands, wetlands and forest margins. These high-fertility ecosystems support rich native plant communities. TUDIES of grazing patterns in South Westland show that the natural regeneration of forest on stable river flats is inhibited by domestic stock. Even light grazing and camping within the forest margin eliminates palatable understorey species, prevents the regeneration of broadleaved plants and can eventually lead to changes in the forest canopy. Concentrated grazing causes the forest margin to retreat. In beech forests east of the South Island’s main divide, grazing animals inhibit the establishment of seedlings by camping and browsing in the shelter of the forest margin. Ironically, there is often healthier regeneration at beech forest margins on nearby pastoral lease country, where strict stock limits apply to the grazing of sheep, than in the major valleys of some national

and forest parks. Natural succession of shrubland and forest on many river flats has been thwarted for years by domestic stock. The impact of stock on forests is not limited to the grazing of palatable plants.

Trampling at forest margins and along cattle tracks compacts the soil, restricts plant root development and reduces plant vigour. Compaction reduces the soil water holding capacity and increases runoff and soil erosion. Heavy trampling

in wet areas leads to soil pugging. Many backcountry walkers are familiar with these slippery cattle tracks several metres wide, that alternate between muddy

wallows and mounds of exposed tree roots. This trampling has an even more devastating effect on wetlands, bogs and streams. Cattle require large quantities of water and enjoy wading and standing in the water they drink. Treading of the stream bed can increase suspended sediments and trampling breaks down the internal water balance of the wetland drainage system. In high-altitude wetlands cattle cause severe damage to sensitive wetland plants, expose the fragile peat soils and can alter the water holding capacity or water yield of the wetland. Turf margins of ponds and tarns can also be severely damaged by cattle trampling. The specialised turf plants may be able to withstand grazing and trampling from soft-

footed animals such as waterfowl, but cannot tolerate the concentrated impact of clumsy, hoofed mammals. Cattle also affect water quality by excreting directly into waterways. This

leads to nutrient enrichment of the stream or bog and increases the risk of spreading disease-causing organisms. Many waterways within protected areas

have a delicate balance between water quantity and flow and very low nutrient levels. Wetlands in the headwater catchments help maintain water quality in

rivers that are important for wildlife, recreation, and downstream urban and industrial uses. Pollution of these waterways is both unnecessary and

unacceptable. Because introduced grasses dominate many river-terrace plant communities, graziers advocate stock access to control tall grass growth and reduce fire risk. Rapid grass growth occurs in spring and early summer and fire risk reaches its height in late summer and autumn. However, the demand for grazing is usually during the winter. Moreover, the intensity of grazing required to effectively reduce the fire hazard would be ruinous to the grassland vegetation and would devastate adjoining forest margins and wetlands. The valley floor grasslands of national and forest parks often form long enclaves, extending for many kilometres into surrounding forest. There is increasing

concern about the impact of. grazing animals on the forest-grassland margin. This biologically rich transition zone suffers most from domestic stock. Fencing is often impractical and usually

* PARKS AND GRAZING°*

very expensive. Besides, fences and gates are usually the last thing people want to see when they leave the farmland to venture into backcountry parks and reserves. The role domestic stock play in maintaining favourable grazing conditions for other introduced animals is unclear, though possums will travel long distances from adjoining forest to feed on short grassland. Introduced predators may also benefit from domestic

stock. Animal carcasses provide a ready meal for wild cats and stoats, sustaining higher populations of these predators. The short-cropped grasslands may also aid predator dispersal. Domestic stock also spread weed seeds. Small hard seeds pass through the gut of grazing animals to be deposited elsewhere in dung. The occurrence of sheep’s sorrel (Rumex acetosella) throughout the eastern South Island, from valley grasslands to alpine shingle screes, is a good example. White clover (Trifolium repens) is also spread by grazing animals. Pasturing stock on grassland with white clover before sending them out to backcountry blocks is a traditional method of establishing this important grazing plant in remote areas. Ground bared by trampling provides favourable sites for weed invasion, and increased fertility from dung often benefits introduced species. Wool, hair and hooves can carry seeds long distances and have been implicated in the spread of ragwort (Senecio jacobaea) in river valleys. Some grazed areas within parks have even been oversown with introduced pasture grasses to improve grazing. ACH YEAR millions of dollars are spent controlling wild animal populations. Yet domestic stock continue to graze within some of the most important protected natural areas in the country. Most of this grazing occurs under DoC licences or permits. In its recently-released draft grazing policy DoC proposes to restrict grazing to 5-year licences with reassessment before renewal (see panel, page 35). Light grazing by sheep can sometimes be beneficial to native plant communities. Monitoring of silver tussock grasslands has shown that sheep help

maintain tussock cover by preferentially browsing competitive introduced grasses. Tussock grasslands are also susceptible to the invasion of introduced woody shrubs or herbaceous weeds. Controlled grazing may be a cost-efficient way of limiting shrub or weed growth. However, there is increasing evidence that grazing patterns influence the susceptibility of a grassland to the invasion of hawkweeds (Hieracium spp.). These opportunistic plants exploit exposed ground and out-compete native species. Increased long-term monitoring is required to determine whether grazing is beneficial in conserving particular values, such as maintaining tussock cover. EVERAL CONSERVATION boards and DoC conservancies are presently tackling the issue of grazing on conservation lands. At Mavora Lakes Park the Southland Conservation Board has decided that grazing is inappropriate and has recommended that grazing cease (see panel). Also in Southland, debate over grazing in the Eglinton Valley has raged in the local papers. Farmers have backed the owners of Te Anau Downs, who graze the adjoining Eglinton Valley, claiming they are dependent on continued grazing of the national park. However, the lack of regeneration at the forest margin and the presence of sheep within the beech forest have alarmed conservationists and park managers. The red and silver beech forests of the Eglinton Valley are an important refuge for the endangered yellowhead and the site of important research into the ecology of forest birds and predators. Continued grazing of the park by domestic stock begs the question whether the park’s primary purpose is nature conservation or to provide off-site benefits for

Grazing at Glenorchy; Mt Aspiring National Park

HE FOREST up valley from the fence was inspected and found to be in a very poor state due to excessive browsing from cattle. There is the main beech canopy but no sub-canopy OF Te Jacement forest. Regeneration and seedlings 0? the forest floor are virtually non-existent. There are the occasional subspecies of horopito, coprosma, and totara which have been heavily browsed. As the canopy forest matures and falls there 18 NO replacement regeneration to provide an acceptable healthy cycle Regeneration is establishing well in areas where cattle have difficult access €-8: steep banks. The track has suffered as a result of stock movement but this would have been the normal situation OveT many years. Mud holes are common with deep ruts in SO erodible soils. np Abhlom.

February aa

the farming community of Southland. In Otago the review of the Mt Aspiring National Park management plan has prompted further discussion of grazing in the park’s backcountry valleys. Farmers claim that they secured agreements that grazing would continue when the park was established. However, no one has been able to produce any such written agreements or binding undertakings. Cattle continue to graze in the park despite severe local damage to forest and stream margins and strong opposition from conservation and recreation groups. Despite the obvious impacts and the concems of park users, expressed through submissions to the management plan review, DoC staff continue to reassure farmers that their right to graze the park will continue. In Mt Cook National Park the grazing of the Birch Hill flats by sheep is being promoted in response to the problem of stock trespassing into the park from the adjoining Tasman riverbed. Potential impacts of stock have been countered by arguments about the difficulty of fencing the park boundary. Little thought has been given to the cause of the problem — stock straying from Glentanner Station onto the Tasman riverbed — or to monitoring of potential impacts of stock on the grasslands and shrublands of the national park. Ironically, Glentanner has probably benefited more than any other high country farm from the neighbouring national park as the station has successfully diversified into tourism enterprises. National parks were set aside to protect vulnerable indigenous ecosystems from the depredations of introduced animals and to allow, where appropriate, public use. The Reserves Act 1977 has the primary purpose of protecting representative examples of the indigenous flora and fauna of New Zealand, particularly from the effects of introduced animals. As a country we have a proud record of setting aside important natural areas, but

protection of those areas from introduced grazing animals is far from satisfactory. And, despite the fact that the vast majority of the countryside has been dedicated to pastoral production, there is continued pressure to compromise protected land for grazing. The integrity of the country’s national parks and reserves is at stake. While the uniqueness of New Zealand’s natural environment and the curiosities it contains are extolled by tourist brochures, the agents of habitat destruction, introduced animals, are tolerated in the country’s main nature tourism destinations. If sheep and cattle and rural landscapes are what tourists come to see there are over 17 million hectares of farmland to satisfy that demand. If it is the unique and

distinctive indigenous plants, animals and landscapes of this unusual land that excite visitors then let us be sure we protect them fully from the effects of domestic stock. The challenge now lies with the conservation boards and DoC to phase out all grazing of domestic stock in national parks and to ensure that the new grazing policy for other public conservation lands does not compromise their ecological and recreational values.

Mike Harding is Forest and Bird’s Christchurch-based field officer. He was formerly a ranger at Arthur’s Pass National Park and is currently working on high-

country conservation issues.