**2. Indigenous forests**

202 Biodiversity Loss in a Changing Planet

3,700 meters on Mount Cook. Climate is highly variable and has played a key role in

As New Zealand has been an isolated land for more than 80 million years, the level of endemism is very high, with more than 90% of insects, 85% of vascular plants, and a quarter of birds found only in New Zealand (Ministry for the Environment, 2007). One of the most notable characteristics of New Zealand's biodiversity is the absence of terrestrial mammals, apart from two bat species, and the dominance of slow-growing evergreen forest. New Zealand's indigenous biodiversity is not only unique within a global context – it is also of major cultural importance to the indigenous Maori people. Maori have traditionally relied on, and used, a range of ecosystem services including native flora and fauna for food,

The isolation of New Zealand has preserved its unique biodiversity, but also rendered the biodiversity vulnerable to later invasion. When Maori migrated from the Pacific Islands, circa 700 years ago, predation upon birds began and much lowland indigenous forest was cleared, especially in the South Island. Rats and dogs were also introduced. The birds, having evolved in an environment free of predators, were susceptible to disturbance and many began to decline to the edge of extinction. When Europeans arrived in the early 19th century, they extensively modified the landscape and natural habitats. Large tracts of land were cleared and converted into productive land for pastoral agriculture, cropping, horticulture, roads, and settlements. Only the steepest mountain land and hill country was left in indigenous forest and shrubland. Swamps were drained and tussock grasslands were burned. Not only was the natural habitat significantly altered, but a large range of exotic species were introduced, including deer, possums, stoats, ferrets, and weasels, causing a rapid decline in native birds and degrading native forest. Other introduced plants and animals have had significant effects in the tussock grasslands and alpine shrublands, most notably rabbits, deer, and pigs, and the spread of wilding pines, gorse, broom, and hieracium. Despite significant efforts to control weeds and pests and halt the loss of natural habitat, around 3,000 species are now considered threatened, including about 300 animals, and 900 vascular plants (Hitchmough et al., 2005). The Economics of Ecosystems and Biodiversity study (TEEB) suggested that it is difficult to manage what is not measured (TEEB, 2010). To prevent further biodiversity loss, decisionmakers need accurate information to assess and monitor biodiversity. However, biodiversity assessment is not a trivial task. As defined by the Convention on Biological Diversity (CBD), biodiversity encompasses "the variability among living organisms from all sources including, inter alia, terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are part; this includes diversity within species, between species and of ecosystems" (CBD, 1992). Conceptually, biodiversity is a nested hierarchy comprising genes, species, populations, and ecosystems. In order to assess status and trend, these multiple levels need to be assessed simultaneously. Noss (1990) suggested a conceptual framework with indicators providing measurable surrogates for the different levels of organisation. Loss of extent is one of the many indicators in this framework, and it has been widely used internationally in reporting to the CBD (Lee et al., 2005). It is relatively easy to report, and has been recognised as one of the main drivers for biodiversity loss (Department

of Conservation [DOC] and Ministry for the Environment [MFE], 2000).

Several national surveys of vegetation cover have been completed. The New Zealand Land Resource Inventory was derived by stereo photo-interpretation of aerial photographs

**1.2 Previous assessments in natural habitat** 

biodiversity distribution (Leathwick et al., 2003).

weaving, housing, and medicines.

Indigenous forests in New Zealand are generally divided into two main types. The first is dominated by beech trees (*Nothofagus*), and the second generally comprises an upper coniferous tier of trees with a sub-canopy of flowering trees and shrubs (the broadleaved species) (Wardle, 1991). However, these two types are not mutually exclusive and mixtures are common. Lowland podocarp-broadleaved forests are structured like forests of the

Provision of Natural Habitat for Biodiversity: Quantifying Recent Trends in New Zealand 205

Fig. 1. Historic land cover (1000 AD) compared with recent land cover (2008). Dark green is

Figure 2 shows the loss of indigenous forest in each of the Level II land environments over the last 18 years. Loss is still evident in many of the land environments. Indeed, nine land environments have lost more than 5% of their remaining indigenous forest. This could be critical, given that eight of those have less than 5% of the land environments remaining in

Approximately one half of New Zealand's land area is made up of a variety of exotic and indigenous grassland ecosystems. Approximately one-fifth of these grasslands comprise modified indigenous short and tall-tussock communities, which are mostly located on the South Island. Unlike many other indigenous ecosystems in New Zealand, they have a unique, partially human-induced origin. Once largely distributed in areas of lowland montane forest and shrubland, large regions of grassland were created through burning by Maori, especially for moa hunting and for encouraging bracken fern (*Pteridium aquilinum*), an important food source (Stevens et al., 1988; Ewers et al., 2006). Lowland podocarp forests hosting such species as totara (*Podocarpus totora*) and matai (*Prumnoptiys taxifolia*) were replaced by a variety of fire adapted grassland species, in particular the short tussock species *Festuca novae-zelandia* and *Poa cita*. Some 200 years later these species were

progressively replaced by taller large grain *Chionochloa* spps (McGlone, 2001).

indigenous forest, light green is indigenous shrubland.

indigenous forest.

**3. Indigenous grasslands** 

tropics. Kahikatea (*Dacrycarpus dacrydioides*) and Kauri (*Agathis australis*) are the tallest trees in New Zealand, and can reach up to 50 metres in height. At maturity these trees tower above the broadleaved canopy with other emergent podocarps like rimu (*Dacrydium cupressinum*), totara (*Podocarpus totara*), matai (*Prumnopitys taxifolia*), and miro (*Prumnopitys ferruginea*), to give the forest a layered appearance. Below the upper canopy many shorter trees, shrubs, vines, tree- and ground-ferns compete for space, and below them, mosses. Beech forests tend to be associated with southern latitudes and higher elevations, such as in mountainous areas, and are generally sparser than the podocarp-broadleaf forests. Their understory may contain only young beech saplings, ferns, and mosses.

Indigenous forests provide unique habitat for a large range of plants, animals, algae, and fungi. Since the arrival of Maori, circa 700 years ago and the subsequent burning of large areas of forest, and then Europeans from ~1840, who cleared large areas for farming and settlement, the extent of indigenous forest has significantly declined and, in combination with many introduced pests, has placed enormous pressure on the survival of many species. MfE (1997) reported that 56 of the listed threatened plant species are from indigenous forest habitats. Also, many of the seriously threatened endemic birds are forest dwellers: wrybill, kiwi, fernbird, kokako, kakariki, saddleback, weka, yellowhead, kaka, and New Zealand falcon.

The extent of indigenous forest in 2008 can be mapped using a combination of LCDB2 and LUM. Theoretically, the LUM contains a recent extent of indigenous forest. However, because the class definitions are land-use rather than land-cover based (for Kyoto Protocol), the indigenous forest class is not the same as the standard definition in LCDB2 and contains much indigenous shrubland yet to reach the maturity of a forest. Hence the LUM should only be used to report on changes to forest if the LCDB definition of indigenous forest is to be used. We therefore combined all the changes "from" or "to" forest in the LUM with LCDB2 to produce a recent extent of indigenous forest.

Figure 1 compares the extent of indigenous forest and shrubland in 2008 with the estimated pre-Maori historic extent, derived by combining LCDB2 and a historic map of New Zealand (McGlone, 1988). In the North Island, the area of indigenous forest has reduced from 11.2 million hectares to 2.6 million hectares. Most remaining indigenous forest is in the hills and mountains. In contrast to indigenous forest, indigenous shrublands have now become extensive, comprising over 1.0 million hectares. These shrublands often comprise a wide variety of indigenous shrub species and could naturally regenerate to indigenous forest if left. In the South Island, the area of indigenous forest has reduced from 12.0 million hectares to 3.9 million hectares, and, similar to the North Island, the remaining forest is mainly in the hills and mountains. At 0.6 million hectares, the area of indigenous shrublands in the South Island is as large as in the North Island.

The loss of indigenous forest between 1990 and 2008 may be assessed directly from the LUM. In the North Island, 29 thousand hectares of indigenous forest have been lost, and in the South Island, 22 thousand hectares of indigenous forest have been lost. The spatial location of this loss is important as some types of forest are better represented than others. We follow the method of Walker et al. (2006) who considered the area of indigenous forest remaining in land environments. The land environments are defined by unique combinations of climate, topographic, and soil attributes, and are a surrogate for unique assemblages of ecosystems and habitats (Leathwick et al., 2003). Four levels of classification have been defined with 20 level I, 100 level II, 200 level III and 500 level IV environments.

Fig. 1. Historic land cover (1000 AD) compared with recent land cover (2008). Dark green is indigenous forest, light green is indigenous shrubland.

Figure 2 shows the loss of indigenous forest in each of the Level II land environments over the last 18 years. Loss is still evident in many of the land environments. Indeed, nine land environments have lost more than 5% of their remaining indigenous forest. This could be critical, given that eight of those have less than 5% of the land environments remaining in indigenous forest.
