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Wageningen University (2008)

Spectral and human sensors : hyperspectral remote sensing and participatory GIS for mapping livestock grazing intensity and vegetation in transhumant Mediterranean conservation areas

Bemigisha, J.

Titre : Spectral and human sensors : hyperspectral remote sensing and participatory GIS for mapping livestock grazing intensity and vegetation in transhumant Mediterranean conservation areas

Auteur : Bemigisha, J.

Université de soutenance : Wageningen University

Grade : Doctor 2008

Présentation
Increasing shortage of pasture resources due to land use conversion constitutes a major challenge to traditional transhumance systems. Reduction of transhumance and related activities leaves the non converted areas abandoned. This may lead to change in grazing intensity, which might result into change in species composition and vegetation pattern. A reduction in grazing intensity might thus influence the biodiversity and forage quality of previously more intensively grazed areas. Proper management of Mediterranean grasslands would require insight on how grazing intensity varies across a landscape and how it influences the distribution and abundance of plant species. The aim of this study was to investigate methods for mapping of livestock grazing intensity and vegetation, using hyperspectral remote sensing, geographic information systems (GIS) and participatory GIS (PGIS). Investigations were undertaken at two main levels. A greenhouse experiment was used to investigate the effects of defoliation and defoliation time for two species grown in mono and mixed culture on the height and dry matter yield as measures of regrowth and competitive ability of two livestock forage grasses selected from a transhumant Mediterranean area. Narrow band hyperspectral reflectance, indices and the red-edge position were investigated to see if they may be used to study these effects. At field landscape level, we tested the use of local people’s knowledge in mapping grazing intensity through the application of PGIS. The results from the greenhouse experiment showed that the species with higher dry matter yield (Lolium multiflorum) had a significantly higher relative regrowth rate and possibly higher competitive ability than its competitor Dactylis glomerata (P < 0.05). Increase in dry matter yield was shown as the trait that determines competitive ability in the early established stage of the two grass species (period of 13 to 18 weeks after sowing). The experiment also provided insight on the persistence of forage species that are of grazing preference. Selective clipping did not alter the competitive ability of D. glomerata to surpass that of L. multiflorum when the former was clipped at lower clipping intensity to simulate selective grazing.

Mots clés : geographical information systems / remote sensing / grazing intensity / mapping / mediterranean region / vegetation / defoliation / mediterranean grasslands

Présentation

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Page publiée le 21 janvier 2015, mise à jour le 2 février 2018