The Boyle Environment

Geography

Located at the end of the St James Walkway the Boyle River Outdoor Education Centre is nestled among the Lewis Pass National Reserve (13 845ha.), Lake Sumner Forest Park (107 222ha.), Poplars Station (7 200ha.) and St James Station (173 340ha.).

The area is characterized by a landscape of mountain peaks, hot springs, lakes, forest, snow tussocks and alpine herb fields.

Geology

The area is characterised by grassy river flats, river terraces and deep gorges due to the river and glacial processes of the past. 14,000 years ago glaciers dammed the region of the Hope River and caused a build up of sediment in the Doubtful and Boyle Valleys. Over time these gravel deltas have been eroded by the rivers leading to a number of steeply sloping gravel bands which have been cut away from the river banks. Shingle fans are aplenty as are scree slopes.

There are several hot springs in the area  that are associated with the numerous fault lines. Three major faults traverse the area running in parallel fashion. The Hope Fault: which heads up the Waiau and Hope valleys; The Clarence Fault: extending from the Kaikoura coast and crossing the area in a NE to SW direction at the Boyle-Lewis confluence; The Alpine Fault: Slightly oblique to the others.

Climate

The Lewis Pass region receives an annual rainfall of about 2800mm. However in the Lewis-Boyle region the rainfall is considerably lower at around 1000mm annually being more on the eastern side of the main divide.

Flora and Fauna

Plant Life

The natural bush line sits at about 1400m.The three main species of plants in the bush are: red beech, silver beech, and mountain beech.

The forest mix up differs greatly from the 450m valley floor to the bush line due to the change in altitude and associated affects: temperature, wind exposure, frequency of snowfall.

The valley floor is predominated by red beech with about 30% coverage of silver beech also. Young lancewoods reach upwards beside thin beech saplings.

There is a fairly dense shrubby undergrowth formed by mainly pepper trees, weeping mapou and the many divaricated coprosmas which intertwine to form a think foliage. On the ground ferns and hook sedges are common.

Moss clad rotting logs litter the forest floor interspersed with clumps of ferns.

On the lower slopes the dominant red beech trees are impressive, some trunks measure at 150 cm in diameter reaching up to 30m in height. The smaller trees are mainly red beech with a smattering of silver beech. Parasite mistletoe can be found growing on the trunks.

Beneath the canopy the broadleaf tree stands out. There are also some marble leaf, totara and lancewood trees in the undergrowth but they are predominated by the presence of bush lawyer. Ground ferns are common.

Above 1000m the red beech thins out to give way to the mountain beech. The undergrowth is low and dense, containing a variety of coprosmas in addition to the mountain beech seedlings. The canopy is more open with many dead branches. A distinguishing feature of the upper slopes is the presence of old mans beard hanging from most branches, probably encouraged by the frequent mist at this level.

At the bush line the vegetation is comprised of prostrate coprosma, snowberry, koromiko, creeping mapou and alpine hard-fern. Quite often scrub plants exceed the height of the mountain beech in the last 50 metres to the bush line itself.

There are a number of bogs on the valley floors and the mountain beech is found lower down as a result, being more resilient. Around the bogs Manuka is typically found alongside bog pine and red tussock.

The alpine grasslands are dominated by carpet grass, snow tussock and musk daisy. The sub-alpine scrub is mostly snow tussock, pale grasses and smaller mat-forming plants in unoccupied areas. Carpet grass, musk daisy, alpine heath and snowberry are frequent underfoot. Numerous other occurrences of mountain daises, mountain flax, mountain cottonwood and buttercup make this zone very picturesque in summer.

Unvegetated rock outcrops are continually being eroded to form scree slopes which head down to the river valleys below.

The prickly shield fern is the most common type of fern in the sheltered wet areas coexisting with a range of mosses, the most predominate being the curved moss.

Animal Life

Large populations of animals from sand flies and bush robins to deer and possums inhabit in the area. There are a high number of threatened native birds such as yellow head and orange-fronted parakeet in the surrounding areas also.

In the bogs one can find backswimmers, water beetles and tadpoles of whistling frogs.

The Lewis Pass are has populations of deer, chamois, brush tail possum. The numbers of possums are relatively low due to a lack of rata but they still feed on manuka, clover, fuchsia, and the five finger.

Red deer are the largest wild mammals in the Lewis Pass area. They are red-brown in summer and grey-brown in winter and have a lighter coloured rump patch.

In the low lying tussock areas hares are common. there are large populations of rabbits though they are gradually being eradicated.

Wild cats have been found in areas closer to human settlement..

There are large numbers of ship rats and house mice in the area with the population changing dramatically every few years coinciding with good seeding years of the beech trees. As a result, brown trout sizes can be rather large as the mice fall into the rivers and streams