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Peter H. Raven


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The Eastern Himalayas

ew places on Earth can match the breathtaking splendor of the Himalayas. The towering peaks and secluded valleys of this mountain range form a 2 400-kilometer barrier separating the lowlands of the Indian subcontinent from the high, dry Tibetan Plateau.

Stretching from lush moist forests in the south to towering snowcapped peaks in the north, the Himalayas feature an astonishing variety of animals and plants. The Eastern Himalayas, located in the rugged mountain terrain of Nepal, Bhutan and northeast India, are a conservation priority for WWF. These ecoregions consist of some of the world's most diverse temperate forests, the world's tallest grasslands with the highest densities of tigers and rhinos in Asia, and alpine meadows rich in plant and animal life. The ecoregions are globally outstanding because they support habitats that protect many of the world's rarest animals, including greater one-horned rhinos, Asian elephants, golden langurs, tigers, takins, red pandas and snow leopards.

Population density and continuing rapid population growth are among the most significant pressures influencing the intensity of land and resource use. In turn, negative patterns of land use contribute directly to the decline of local habitats and species. In an effort to clarify the distribution and intensity of negative pressures associated with humans and their activities, WWF has mapped several population variables across the Eastern Himalayan region. By overlaying these variables with habitat or species data onto one map, high biodiversity regions under the greatest threat from population pressures are revealed. Focused conservation action needs to occur when these areas contain unique and irreplaceable species or habitats.

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The major human activities that threaten biodiversity in the Eastern Himalayas are agricultural conversion, overuse of forest resources, hunting and overgrazing. The intensity of many of these human induced pressures is positively correlated with population density, which follows a steep, positive gradient from east to west and from north to south. The highest densities are reached in the Tarai, a grassland in the south of Nepal, Bhutan, and the Indian states of Sikkim and Arunachal Pradesh. Up until the mid-1950s this region was populated only by Tharus, an ethnic group with genetic immunity to malaria. Once malaria was brought under control, the Tarai's rich agricultural land attracted migrants from both the mountainous north and Indian plains to the south. The subsequent growth in people and agriculture since the 1950s is mirrored by the decline in forests, natural grasslands and their wild inhabitants.

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A more direct link between humans and habitat can be made by combining human density and remaining forest figures into one ratio. People in the Eastern Himalayas depend upon the forests for timber, fuelwood, grazing, foraging, sub-canopy plantations of cardamom, and many other uses. At the same time, the forest represents important habitat for the majority of the region's fauna. Mapping the area's forest to person ratio indicates the relative level of pressure human population exerts on habitat. The lower the ratio, the less forest available per person and the higher the pressure on habitat. All of Nepal shows a great deal of pressure on remaining forests, leaving a threatening situation for protected areas which may be the only source of forest products for the local population. The further east in the ecoregion, the more forests are left, with especially high values in Arunachal Pradesh and Myanmar. The forests in these high value regions are most certainly in better condition with more intact species assemblages.

Population growth in the Eastern Himalayas averages 2.1 per cent per year with a maximum of 4.83 per cent in the Kailali district in Nepal. The doubling time for 2.1 per cent is approximately 33 years, while the doubling time for 4.83 is just over 14 years. The short doubling time underscores the fact that slowing population growth is desirable from both human and ecological standpoints.

Birth rate is one of the factors that control growth rate. A practical measure of birth rate is total fertility, which measures the average number of children that women would have, assuming that these women had children at the average rate for each period in their lives. Statistics from Nepal show that, in recent years, the total fertility rate is declining. Growth in both the urban and rural environment can be influenced to decline by increasing access to health facilities and raising the female literacy rate. WWF is encouraging activities that will help accelerate progress in these two areas.

Biologists agree that, due to the limited effectiveness of small, isolated protected areas, conservation must occur in areas inhabited by people. However, in doing this, potential conflicts between human development and conservation will increase, as will the need for innovative solutions to address both elements. Demographic maps give WWF a good indication of where pressure on habitat and species is most acute. WWF is reallocating much of its efforts to areas where high human pressure and recognized biological importance coincide. Within these areas, WWF is seeking and applying strategies to help foster behavior and attitudes that will better serve conservation goals.

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