INTRODUCTION

Habitat loss is the main threat to biodiversity. Conversion of land to urban sprawl and agricultural land is widespread, particularly in southern temperate regions. In the boreal forest zone, landscapes have remained primarily forested while undergoing spatial and temporal changes in composition and age structure. Within the seemingly intact forest cover, habitat degradation has resulted in habitat loss for many species. Common to these types of landscape changes is that human activities have resulted in a shortage of area for species and their habitats. Preventing further habitat loss, that is conservation, causes restrictions to other land-use types and often incurs considerable economic costs in terms of foregone opportunities. Therefore, there is an immanent tradeoff between alternative land-use practices. How much trading in ecological values we are willing to accept for increasing economic welfare is an important ethical question, and relates to the discussion of weak versus strong sustainability (Costanza 1996). From a scientific point of view, the tradeoff between ecological and economic targets calls for the development of procedures and methods to cope with it in a balanced way.

The tradeoff between ecological and economic targets reflects land-use demands. Market value of land varies widely across sites according to, for example, location, potential other uses, and primary productivity. Pressures to develop a parcel of land increase in proximity to dense human populations, yet social benefits from undeveloped land (e.g. recreation and conservation) also increase with proximity. Therefore, land value tends to decrease with distance from cities.