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Title A 27 year-old observatory in the Sahel savanna of N Senegal - design, present results, chances and limitations for long-term biodiversity monitoring

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Short title A 27 year-old observatory in the Sahel savanna of N Senegal

Author(s) Miehe, S.(1); Kluge, J.(2); Culmsee, H.(2)

Presenting author Miehe, S.

Institution(s) (1) Faculty of Geography, University of Marburg; (2)Albrecht-von-Haller-Institute for Plant Sciences, University of Goettingen

Keywords Observatory; Sahel; Senegal; grazing experiment; exclosures

Abstract In the sandy Ferlo of N Senegal, 25 permanent 1ha-observation plots around the deep well Widou Thiengoly (15°59’ N, 15°19’ W, 300 mm long-term annual rainfall) were installed in 1981 in order to monitor vegetation changes in the course of a grazing experiment of the GTZ (Deutsche Gesellschaft für Technische Zusammenarbeit) within the framework of senegalo-german technical cooperation. The experiment provided data on vegetation changes under three different grazing regimes: controlled pasture on fenced plots, free communal pasture and ungrazed regeneration plots. The total area represented by these observation plots was 3 x 7 km. Daily rainfall and the standing crop of the herb layer were determined every year, the composition of the herb layer annually since 1992, before in intervals of 4-5 years. Trees and shrubs were inventoried every 4 to 5 years; saplings were counted annually. Additionally, spot checks of topsoil nutrients were made in 2006.
Vegetation changes under the three treatments were partly superimposed by effects of the relief/soil conditions and by climatic oscillations. Whereas the communal pasture showed degradation processes, the ungrazed savanna recovered from both, the recent droughts and former anthropo-zoogenic impact.
The present monitoring design is critically discussed and chances and restrictions of data evaluation are outlined for compatibility with the BIOTA concept.

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Notes Presentation planned in the context of the working group on African Biodiversity Observation Network

Ref. No. 670