Bush cover and range condition assessments in relation to landscape and grazing in southern Ethiopia

被引:107
作者
Oba, G [1 ]
Post, E [1 ]
Syvertsen, PO [1 ]
Stenseth, NC [1 ]
机构
[1] Univ Oslo, Dept Biol, Div Zool, N-0316 Oslo, Norway
关键词
bare soil; Booran; bush cover; dry savannah; grass cover; grazing pressure; landscape patch types; landscape units; pastoralists land use; soil erosion; southern Ethiopia;
D O I
10.1023/A:1008106625096
中图分类号
Q14 [生态学(生物生态学)];
学科分类号
071012 ; 0713 ;
摘要
Progressive growth of bush cover in dry savannahs is responsible for declines in range conditions. In southern Ethiopia, the Booran pastoralists assisted our understanding of spatial patterns of bush cover and range conditions in 54 landscape patch types grouped into six landscape units within an area of 30 000 km(2). The size of landscape patches sampled was 625 m(2). We assessed the relationships between bush cover, grass cover and bare soil and grazing pressure and soil erosion and changes in range condition. Externally, political conflicts and internally, break down of land use, and official bans on the use of fire promoted bush cover and the decline in range conditions. Bush cover was negatively correlated with grass cover, and positively correlated with bare soil. Grass cover was negatively correlated with bare soil and grazing pressure in most landscape patch types. Grazing pressure was not significantly correlated with bush cover or bare soil, while soil erosion was directly related to bare soil. Soil erosion was absent in 64% of the landscape patch types, and seemingly not a threat to the rangelands. The relationship between bush cover, grass cover, bare soil and soil erosion is complex and related to climate, landscape geology, and patterns of land use. Main threats to range conditions are bush climax, loss of grass cover and unpalatable forbs. Currently, > 70% of the landscape patch types are in poor to fair range conditions. Decline in range conditions, unless reversed, will jeopardise the pastoral production system in southern Ethiopia.
引用
收藏
页码:535 / 546
页数:12
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