For wildlife and ecosystems, however, it is the cumulative impacts of numerous pressures that determine actual effect on the abundance of species, including, but not limited to, infrastructure development and associated land use, forestry, agricultural practices, nitrogen pollution and climate change.

In this section biodiversity has been defined as the average abundance of the original species compared with their original abundance when ecosystems were hardly impacted by people. The abundance of a species means the population size of number of individuals of species. This indicator is in accordance with the indicators agreed upon under the Convention of Biological Diversity (UNEP, 2004).

Figure 16:Current and projected reduction in abundance of biodiversity, expressed as percent of original abundance of biodiversity given no human disturbance. The four scenarios depict the cumulative impacts of climate change, infrastructure development, land use, forestry and N-pollution. Notice that the projections are model outputs on very general datasets and should be used with caution for other than depicting trends.

Ecosystem function most generally is closely related to its original species and their abundance. Given dose-response curves of different human pressures and their subsequent impact on biodiversity, it is possible to model not just the area under pressure, but also provide a range of estimates for what different human pressures may actually mean in terms of reduced species abundance. It is furthermore possible – based on these pressure species response curves to provide estimates on the relative significance of different pressures for biodiversity loss at different times out in the future.

Projections of the relative loss of biodiversity today and in 2030 given different scenarios are presented in Fig. 16. Areas with high human densities and where infrastructure development has been associated with intensive agricultural production and forestry, biodiversity loss has been the greatest compared to less developed areas. This is also evident in all four scenarios. Biodiversity loss is highest in lowland regions, up to more than 80% reduction in the abundances of original biodiversity. Notice that this doesn’t mean that 80% of the species are extinct, but that the populations sizes  of  species – on average – are less than 20% of what they were before human intrusion altered habitats. Few may be extinct, many strongly reduced and a few – human favored – species strongly expanded, by which various ecosystems are becoming more and more alike. The situation is particularly severe in lowlying densely populated areas of China, Pakistan, Bangladesh, India, Myanmar and other parts of Southeast-Asia. These are the areas also exposed to the most extensive human and agricultural exploitation.

While the large protected areas in interior Tibet will largely help protect against biodiversity loss (given control of poaching), many upland areas, such as the expanding areas around settlements and irrigated lands in Xinjiang and Qinghai, and forests in Sichuan and Yunnan of China will experience 20-40% declines in abundances of biodiversity if special attention is not given to these areas. The same applies to mountain ranges Kyrgyzstan, Tajikistan, Afghanistan, Pakistan and lowland Nepal.

Figure 17:The relative significance of different pressures for projected biodiversity loss in the study region 2000-2050 (GLOBIO 3.0).

Large unproductive mountain ranges have been protected in many of the countries, but the inhabited up- forest and mountain slopes remain vastly unprotected. These are also the areas with the heaviest land use and population pressures in the mountains and are critical for water management issues and risk of floods in lowland farmlands.

The scenarios of biodiversity loss also provide interesting information on the relative significance of the different pressures for biodiversity and ecosystem impacts. This is particularly important for policy purposes. While the losses directly attributable to climate change increases from 4 to 8% over a few decades, agricultural expansion and infrastructure development and associated land use pressures are the by far most significant threats to biodiversity. Indeed, those two factors account for a relative 75-78% of the projected loss in abundance of biodiversity up to 2050 (Fig. 17).

Hence, while climate change is likely to produce severe impacts in terms of extreme weather conditions, glacial outbursts (the flash-floods associated with unusual melting of glaciers)(Blyth et al., 2002) and retreats, the immediate threats to ecosystems and biodiversity including risk of floods is primarily related to unsustainable land use practices. By strengthening the resilience of plants and wildlife through the development of protected areas, the risk of floods, land slides, erosion and loss of ecosystem services may largely be reduced. However, it is important to notice that given an overall intensifying land use, the vulnerability of plants to climate change will also increase substantially.