nl0601 rodents

The Sanjiangyuan Nature Reserve, the second largest nature reserve in the world (152,300 km²) and the highest and most extensive protected wetland area in the world, was established in May 2000 by the State Forestry Administration and the government of Qinghai Province, China . On an average altitude of over 4000 m it is situated in the Sanjiangyuan region (320,000 km²) in the southwest of the Qinghai-Tibetan Plateau (Plateau Perspectives 2006). Its large expanses of high-altitude peatlands and mountain meadows, known as the “Chinese water tower”, are of global significance for biodiversity conservation and carbon storage. As the headwater of the Yangtze, the Huang and the Lancangjiang River the area is of high importance for regulating water storage and supply for large areas of the Chinese lowlands. Five thousand years of traditional nomadic herding (Wiener et al. 2003) have altered the ecosystems on mineral and organic soils and have lead to substantial changes in soil hydraulic conditions in the peatlands that made the area susceptible to degradation. Recent peatland drainage to increase vegetation productivity and carrying capacity and overgrazing have triggered a whole chain of negative processes leading to decreased productivity and immense losses of grazing ground by erosion and desertification (Wu 2000, Schumann & Joosten in press).

First signs of degradation due to overgrazing by yaks and sheep. Photo: Martin Schumann (Hongyuan, 2005)

Some pastures have degraded to the extent that perennial vegetation has disappeared and annual grasses and forbs, which are completely devoured by grazing animals, establish (Ma 1998). The degradation on the Qinghai-Tibetan Plateau (Tab. 1) is one of the most serious environmental and socio-economic issues of the area.

Tab. 1: Areas (in 10,000 ha) and distribution of degraded rangelands on the Qinghai-Tibetan Plateau: (Long & Ma 1997)

Province	Available rangeland	Degraded rangeland
Province	Available rangeland	1980s	1990s
Tibet	6636.1	1202.6	1990.8
Qinghai	3161.0	910.3	1005.5
Sichuan	1416.0	386.7	467.3
Gansu	1607.2	712.9	787.5
Total	12820.4	3212.4	4251.1

So called “rat infestations” aggravate the scene of destruction after initial degradation. By consuming aerial biomass and roots of plants as well as by covering swards by digging up soil, Ochotona curzoniae (Plateau Pika or Black-lipped Pika) as well as Myospalax fontanierii (Chinese Zokor or Highland Zokor) (Wiener et al. 2003, Foggin 2000) have worsened degradation of more than 6.4 million hectares of grassland in the Sanjiangyuan region (33 %) and up to 70 % in other regions (CEN 2006).

Rats enhance degradation after drainage and intensive grazing. Photo: Martin Schumann (Ruoergai, 2005)

Traditionally herders install traps and spread poisoned baits to remove rodents from their pastures. Because the rodents have strong migrant and reproduction abilities (during periodic infestations up to 148 animals have been counted per ha, Wiener et al. 2003), these measures are not sufficiently effective. Instead, the poisoning made the rodents resistant to the chemicals and has lead to the death of their natural predators, such as eagles, foxes, and wolfs. An increase of the population of natural predators as well as a reduction of overgrazing would be a sustainable and more effective alternative to cut back rodent populations to harm-free levels.

With its 11^th Five-year plan for development China ’s ruling Communist Party is now focusing on water and energy conservation. It will provide 7.5 billion yuan (925 million US $) to develop better poisons or methods to kill rodents, to reduce overgrazing, and to relocate farmers and herdsmen from affected areas (CEN 2006).

The killing of rodents – Fighting peatland degradation on the Qinghai-Tibetan Plateau ( China )

The killing of rodents –
Fighting peatland degradation on the Qinghai-Tibetan Plateau ( China )