Biomass and quality changes of forages along land use and soil type gradients in the riparian zone of Lake Naivasha,Kenya |
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Affiliation: | 1. Faculty of Veterinary Sciences, National University of the Centre of the Buenos Aires Province, Tandil, Argentina;2. Faculty of Agriculture and Forestry Sciences, National University of La Plata, La Plata, Argentina;3. Riograndense Rice Institute, Porto Alegre, Brazil;4. Department of Animal Nutrition and Management, Swedish University of Agricultural Sciences, Uppsala, Sweden;1. Assistant Professor, Department of Bioresource Engineering, McGill University, Sanite-Anne-de-Bellevue, QC H9X 3V9, Canada;2. Plant Physiologist, US Department of Agriculture (USDA)-ARS Rangeland Resources Research Unit, Crops Research Laboratory, Fort Collins, CO 80526, USA;3. Research Agronomist USDA-ARS Agricultural Systems Research Unit, Fort Collins, CO 80526, USA;4. Research Leader, USDA-ARS Agricultural Systems Research Unit, Fort Collins, CO 80526, USA;5. Research Leader, USDA-ARS Rangeland Resources Research Unit, High Plains Grasslands Research Station, Cheyenne, WY 82009, USA;1. CIHEAM Mediterranean Agronomic Institute of Bari, Via Ceglie 9, 70010 Bari, Italy;2. University of Naples “Parthenope”, Via Amm. F. Acton 38, 80133 Napoli, Italy |
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Abstract: | The recession of the water level of Lake Naivasha has incrementally exposed land surfaces creating a chronosequential transect representing durations of 1–30 years of exposure to grazing. This chronosequence provides a unique model to study the effects of land use duration on resource availability and resource base quality. Particularly, pasture quality changes in the riparian land of tropical fresh water lakes have so far not been studied. We assessed the effect of the duration of exposure to grazing on the biomass production, crude protein content and energy quality of pastures in a 4 × 4 latin square design (4 chronosequence positions × 4 soil types). Species composition was recorded and biomass was sampled at monthly intervals from February to August 2011. Soil moisture was recorded using frequency domain reflectometry sensors. Vegetation samples were analyzed for dry matter, nitrogen and metabolizable energy. Increased land use duration favored a shift in species dominance from Pennisetum clandestinum to Cynodon plectostachyus, which was associated with a reduction in dry matter yield and increased plant nitrogen content. All measured variables tended to be higher in soils formed on alluvial than in those formed on lacustrine deposits. Increased soil N and gravimetric moisture content stimulated biomass accumulation. The crude protein yield and metabolizable energy changed with phenological stages of the pasture and declined significantly towards maturity (seed setting of grasses). Continuous grazing and reduced soil moisture content, both during low rainfall and increased distance from the lake shore, affected the composition of pasture grasses as well as forage yield and quality. This may thus differentially affect the suitability of the riparian land as pasture ground and feed resource area for grazing animals. |
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Keywords: | Chronosequence Pasture quality Wetland |
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