Biodiversity is a term now commonly used in the political arena. However, it has a fairly strict definition that is widely recognized in ecology. In essence, biodiversity refers to genes, species, and ecosystems as levels of organization, and it includes ecosystem structure and function (Noss 1990). These different aspects of biodiversity must also be the starting point for setting conservation goals for forest landscapes. However, when applied to forest management, biodiversity objectives must be broken down into measurable targets based on clear and, preferably, functional links to the overall goals.
Around the world, relatively pristine forest ecosystems have been preserved through the foresight of a few individuals, have been restored at great cost, or they simply persisted by default owing to slow economic development. In regions that are still undeveloped (e.g. portions of the boreal forest or the Amazon basin), targets may be set as proactive measures to limit impacts of foreseeable economic development (see also Chapter 4, this volume). In regions where conservation planning has maintained an intermediate level of ecological integrity, targets must still be set to protect sensitive species or critical ecological processes (see Chapters 8, 9, and 10, this volume). Finally, conservation targets may also represent useful tools to monitor the success of ecological restoration (see Chapter 11, this volume) in regions where major habitat loss and conversion have taken place.
Any specific target is relevant to a temporal and spatial domain. In addition, it may relate to different levels of conservation ambition.