Habitat loss and global biodiversity loss 2000–2050
To understand the rising risk to migratory species, it is impera- tive to begin with an overview of global changes and declines in biodiversity worldwide, as this pattern is an even greater threat to migratory species than to most non-migratory species.
The “Big Five” primary causes of biodiversity loss in general are habitat destruction/fragmentation, overharvesting/poaching, pollution, climate change and introduction of invasive species. These impacts affect virtually all species on the planet, both sedentary and migratory alike.
There are several global scenarios of biodiversity but all consistently point to further biodiversity loss across the next century, however at differing rates (Perira et al., 2011). Scenarios of future habitat
loss by the GLOBIO 3.0 model have been used extensively by vari- ous agencies of the United Nations, the Organization for Econom- ic Co-operation and Development (OECD) and the Convention on Biological Diversity (CBD) (see www.globio.info), and suggest, like most other models, a substantial increase in both the rate and ex- tent of biodiversity loss over the next four decades (Fig. 5a-e).
The CBD estimates that the accelerating rate of deforestation, which has taken place over the last century, has contributed to reducing the abundance of forest species by more than 30 per cent. The rate of species loss in forest regions is considerably faster than in other ecosystems. Between now and 2050, it is projected that there will be a further 38 per cent loss in abun- dance of forest species (UNEP-GLOBIO 2008).
Photographic impression of mean species abundance indicator Grassland Original species Extensive use Subsistence agriculture Intensive agriculture
Mean abundance of original species
100% Pristine forest Selective logging Secondary vegetation Plantation
Figure 4: A photographic demonstration of what Mean Species Abundance (MSA) means in terms of changes in the landscape and its wildlife (UNEP, 2009).