<i>Cyperus papyrus</i> L. Growth Rate and Mortality in Relation to Water Quantity, Quality and Soil Characteristics in Nyando Floodplain Wetland, Kenya

Abstract

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 m 2 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 NH 4 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.

Impact of dietary leaf extracts of Black pepper Piper nigrum L. on the growth, hematological and immunological parameters of Labeo rohita (Hamilton, 1822) cultured in glass aquaria

“…The physicochemical characteristics of water samples i.e., temperature (°C), pH, electrical conductivity (mScm -1 ), total hardness (mgL -1 ), total ammonia (mgL -1 ), dissolved oxygen (mgL -1 ), and carbon-dioxide (mgL -1 ) concentrations were determined in 12-hour intervals in each glass aquarium by following the methods of American Public Health Association (APHA, 1998) and Rongoei and Outa (2016). Each glass aquaria was supplied with continuous aeration under controlled laboratory conditions at constant controlled water temperature (30 °C), pH (7.5), and total hardness (200 mgL, -1 ), respectively.…”

The effect of seasonal flooding and livelihood activities on retention of nitrogen and phosphorus in Cyperus papyrus wetlands, the role of aboveground biomass

“…For the culms showing maximum growth, model II linear regression lines were estimated between mean culm length (X) and relative growth rate (Y) (Fig. 3), using the lmodel2 package in R. The parameters r and K of the logistic curve were calculated for each transect from the intercept and slope (Rongoei & Outa, 2016). The same method for determining the logistic growth models was used for width and girth.…”

Implications of Papyrus (<i>Cyperus papyrus</i> L.) Biomass Harvesting on Nutrient Regulation in Nyando Floodplain Wetland, Lake Victoria, Kenya

“…The harvested parts may be used for various purposes depending on the needs of the harvesters which can be to meet subsistence and commercial needs of the households in the study sites ( Table 2). Harvesting of the plant species, the rate of decomposition, growth rate and their ability to oxygenate the rhizosphere, which may influence nutrient cycling [25] [26]. Different growth stages varied in the nutrient concentration in their tissues where young stage papyrus plants had the highest concentration of nutrients than those senescing, and drying plants.…”