Cyperus papyrus (L.) growth rate and mortality is influenced by environmental conditions prevailing in the wetland. To assess growth dynamics of C. papyrus in relation to water depth and anthropogenic (exploitation) p...Cyperus papyrus (L.) growth rate and mortality is influenced by environmental conditions prevailing in the wetland. To assess growth dynamics of C. papyrus in relation to water depth and anthropogenic (exploitation) pressures, monthly and bi-monthly measurement of culm length and girth were done between June and December 2010 (period 1) and April to June 2011 (period 2). Three study sites were selected based on the water levels and livelihood-driven exploitation pressures. Surrogate measurements of individual culm height and girth were done in three 1 m2 quadrats in each site to determine the growth rate of papyrus. Water depth was lowest in period 2 (dry) and highest in period 1 (wet) which was related to the livelihood activities being highest in period two and lowest in period one. Culm mortality occurred throughout the study period with 64% due to natural senescing while insect/rodent accounted for 19%. Papyrus growth was higher in Singida (2.5 ± 0.2 cm/day) representing less disturbed site and least in Wasare (1.4 ± 0.1 cm/day) which was highly disturbed. Multiple regression models for culm length showed culm density, mean length and NH4 negatively influenced growth rate while site as a dummy variable, water depth, SRP and TP had positive effects on papyrus growth rate. Understanding growth rate and causes of mortality in papyrus is important to establish sustainable management strategies of this ecosystem to maintain its integrity.展开更多
Harvesting of papyrus biomass plays a significant role in regulating ecosystem services of which one of them is nutrient uptake and cycling. Despite Lake Victoria’s wetlands being important, little is understood abou...Harvesting of papyrus biomass plays a significant role in regulating ecosystem services of which one of them is nutrient uptake and cycling. Despite Lake Victoria’s wetlands being important, little is understood about its role in nutrient uptake and removal. Although there have been studies done in these wetlands, there is inadequate understanding on the implication of unselective biomass harvesting on the water quality of Lake Vitoria. At the same time, these wetlands are threatened by livelihood-related pressures which are driven by extreme hydrological regimes. This study focused on Nyando floodplain wetland located in the Eastern part of the shores of Lake Victoria which is a lifeline to many rural communities living around the lake. Papyrus biomass harvesting was assessed in two study sites of Nyando wetland and at different seasons in order to determine its implication on nutrient regulating services. Participatory tools, field survey, observation, field measurements and laboratory analysis were used. Harvesting of papyrus removed 530.6 Kg N/g DM/ha/day and 97 Kg P/g DM/ha/day in Ogenya while 771.2 Kg N/g DM/ha/day and 109.2 Kg P/g DM/ha/day were removed in Wasare. However, addition of nutrients to the wetland may lead to the problem of eutrophication especially at the site where interaction of wetland and lake water occurs. Understanding the role of papyrus harvesting patterns is crucial for better planning and management of this complex resource in a changing environment.展开更多
文摘Cyperus papyrus (L.) growth rate and mortality is influenced by environmental conditions prevailing in the wetland. To assess growth dynamics of C. papyrus in relation to water depth and anthropogenic (exploitation) pressures, monthly and bi-monthly measurement of culm length and girth were done between June and December 2010 (period 1) and April to June 2011 (period 2). Three study sites were selected based on the water levels and livelihood-driven exploitation pressures. Surrogate measurements of individual culm height and girth were done in three 1 m2 quadrats in each site to determine the growth rate of papyrus. Water depth was lowest in period 2 (dry) and highest in period 1 (wet) which was related to the livelihood activities being highest in period two and lowest in period one. Culm mortality occurred throughout the study period with 64% due to natural senescing while insect/rodent accounted for 19%. Papyrus growth was higher in Singida (2.5 ± 0.2 cm/day) representing less disturbed site and least in Wasare (1.4 ± 0.1 cm/day) which was highly disturbed. Multiple regression models for culm length showed culm density, mean length and NH4 negatively influenced growth rate while site as a dummy variable, water depth, SRP and TP had positive effects on papyrus growth rate. Understanding growth rate and causes of mortality in papyrus is important to establish sustainable management strategies of this ecosystem to maintain its integrity.
文摘Harvesting of papyrus biomass plays a significant role in regulating ecosystem services of which one of them is nutrient uptake and cycling. Despite Lake Victoria’s wetlands being important, little is understood about its role in nutrient uptake and removal. Although there have been studies done in these wetlands, there is inadequate understanding on the implication of unselective biomass harvesting on the water quality of Lake Vitoria. At the same time, these wetlands are threatened by livelihood-related pressures which are driven by extreme hydrological regimes. This study focused on Nyando floodplain wetland located in the Eastern part of the shores of Lake Victoria which is a lifeline to many rural communities living around the lake. Papyrus biomass harvesting was assessed in two study sites of Nyando wetland and at different seasons in order to determine its implication on nutrient regulating services. Participatory tools, field survey, observation, field measurements and laboratory analysis were used. Harvesting of papyrus removed 530.6 Kg N/g DM/ha/day and 97 Kg P/g DM/ha/day in Ogenya while 771.2 Kg N/g DM/ha/day and 109.2 Kg P/g DM/ha/day were removed in Wasare. However, addition of nutrients to the wetland may lead to the problem of eutrophication especially at the site where interaction of wetland and lake water occurs. Understanding the role of papyrus harvesting patterns is crucial for better planning and management of this complex resource in a changing environment.
