Environmental conditions and human drivers for changes to north Ethiopian mountain landscapes over 145 years.
As quantitative or spatially distributed studies of environmental change over truly long-term periods of more than 100 years are extremely rare, we re-photographed 361 landscapes that appear on historical photographs (1868-1994) within a 40,000 km(2) study area in northern Ethiopia. Visible evidence of environmental changes apparent from the paired photographs was analyzed using an expert rating system. The conditions of the woody vegetation, soil and water conservation structures and land management were worse in the earlier periods compared to their present conditions. The cover by indigenous trees is a notable exception: it peaked in the 1930s, declined afterwards and then achieved a second peak in the early 21st century. Particularly in areas with greater population densities, there has been a significant increase in woody vegetation and soil and water conservation structures over the course of the study period. We conclude that except for an apparent upward movement of the upper tree limit, the direct human impacts on the environment are overriding the effects of climate change in the north Ethiopian highlands and that the northern Ethiopian highlands are currently greener than at any other time in the last 145 years.
Ghent University, Department of Geography, Gent, Belgium. Electronic address: Jan.Nyssen@UGent.be.
Jan
J
Nyssen
Ghent University, Department of Geography, Gent, Belgium.
Amaury
A
Frankl
Department of Land Resources Management and Environmental Protection, Mekelle University, Ethiopia.
Mitiku
M
Haile
Department of Geography, University of Berne, Switzerland.
Hans
H
Hurni
Wageningen University, Wageningen, The Netherlands.
Katrien
K
Descheemaeker
Department of History, University of Illinois, USA.
Donald
D
Crummey
Department of Geography, University of Berne, Switzerland.
Alfons
A
Ritler
Department of Geography, University of Berne, Switzerland.
Brigitte
B
Portner
Institute of Zoology, Zürich University, Switzerland.
Bernhard
B
Nievergelt
Royal Museum for Central Africa, Tervuren, Belgium.
Jan
J
Moeyersons
Old Abbey Associates, Dirleton, Scotland, UK.
Neil
N
Munro
Department of Earth and Environmental Sciences, KU Leuven, Belgium.
Jozef
J
Deckers
Earth Sciences Institute, University Ferrara, Italy.
Paolo
P
Billi
Department of Earth and Environmental Sciences, KU Leuven, Belgium.
Jean
J
Poesen
D000383:Agriculture; D057231:Climate Change; D003247:Conservation of Natural Resources; D004777:Environment; D004784:Environmental Monitoring; D005002:Ethiopia; D006801:Humans; D011156:Population Density
Environmental rehabilitation; Land management; Reforestation; Repeat photography; Soil and water conservation; Woody vegetation