History

Turnbull’s Bush

Background

Aerial View of Sherwood Forest, Tussock CreekTo fully understand the importance of this forest stand, it is important to know something of the vegetation history of Southland. The original vegetation of Southland is largely remnant in nature. Much of the Southland Plains was clothed in a mosaic of forest types, dependant largely upon the topography and hence the moisture. Kahikatea dominated forests were found in the swampy areas, matai dominated in the low-lying better drained areas. Wherever there are hills or greater topographical vegetation and consequently better drainage, rimu becomes dominant. However, not all of Southlands Plains was clothed in forest. Some less fertile areas (probably in wet areas and possibly with peat soils) would have been clothed in red tussock. Red tussocklands were also more common around the edge of the plain in the north (where it may have been burning induced). The true peatlands would have contained peatland vegetation dominated by wire-rush (Empodisma Minus) with much tangle fern (Gliechena dicarpa), manuka (Leptospermum Scoparium) and turpentine shrub (Dracophyllum longifolium).

With the arrival of humans the vegetation changed. The Maori increased the frequency of fires; this removed some of the forest which was replaced by red tussocklands and shrublands. With the colonisation by Europeans there were even greater changes. The Southland Plains were generally flat and fertile and so were cleared for agriculture, with the tall timber being milled. Now only a small proportion of the original cover remains. However the most fertile and easy to develop areas along the rivers were more completely developed, very little of these forests now remain.

Although the Southland Plains retain a number of forest areas many have been milled or selectively logged at some time and most have had or still do have access to stock. Many of the reserves are smaill and their long-term fate is uncertain because of the edge effects of wind damage and stock damage. Some reserves are changing because drainage has altered the soil moisture and hence site conditions required for seeding germination and growth.

Introduction

The importance of this forest area is not only that matai-dominated forests are now amongst the least common but for several other reasons. It is a relatively large size and being adjacent to part of the Mabel Bush Scenic Reserve so combines to form a much larger, more viable and so more significant forest area. Although dominated by matai forest there is some variation in this and there are other communities present as well.

Communities

The reserve contains three main communities, the most extensive being matai forest, with smaller areas of kahikatea forest (the ‘Everglades’) and a swamp area.

Matai Forest: Matai is dominant, forming a near continuous forest canopy. Also reaching the forest canopy is pokaka along with occaisional kahikatea, Pennantia corymbosa and broadleaf. The forest is not particularly tall, being only c.12m in more exposed sites and up to 15+m tall in more sheltered areas. The understory is open and dominated by shrubs, there being practically no small tree layer. The most common shrubs are Melicope simplex and a variety of Coprosma species (mainly Coprosma rotundifolia, c rubra and C rhamnoides) with some weeping mapou and Neomyrtus pendudnculata. The forest floor is not diverse, still recovering from a history of cattle grazing. The most common species on the forest floor are prickly shield fern and a variety of Blechnum ferns, herbs are not common.

Along the side of the old Makarewa River is found Kowhai, lacebark, koromiko and mingimingi.

Kahikatea Forest: This is found in the area called the Everglades. This forest is found in a wetter area (high water table). This area was not examined so is not discussed further.

Swamp: This has standing water and is dominated by niggerhead, and a variety of introduced water tolerant plants. The edge of the swamp contains a narrow zone with much mingimingi and Blechnumsp ‘swamp’. Beyond this the matai forest contains much Coprosmarigida and Fuchsia colensoi along with some lacebark, kowhai and Melicytus cingustifolius.

Most of the swamp area has a water table which is sufficiently high to ensure its survivsl in the future. Part of the swamp is only seasonally wet. A small part which is only occaisionally inundated may be invaded and eventually tend to forest.