Browsing by Author "Banyikwa, Feetham F."

Now showing 1 - 20 of 30
  • Thumbnail Image
    Item
    Above-Ground Carbon Allometric Models for Diplorhynchus condylocarpon (Müll. Arg.) Pichon., A Common Miombo Woodland Associate
    (2015-07) Mganga, Nyatwere D.; Lyaruu, Herbert V.M.; Banyikwa, Feetham F.
    Estimation of carbon using allometric models facilitates sustainable management of forests and woodlands. Reliable estimations of carbon in most ecosystems can only be accomplished by using species-specific allometric models which are lacking for many species. The present study was carried out so as to develop the best fit above-ground carbon allometric models of various tree components; stems, branches, twigs and leaves of Diplorhynchus condylocarpon (Horn-pod tree), a species that is commonly associated with Miombo woodlands. Twenty one trees of D. condylocarpon with a ranging diameter at breast height (DBH) from 5 to 19 cm were destructively sampled from Miombo woodlands of Kitwe in Tanzania. Linear models were assessed for above-ground carbon using regression analysis. Regression analysis was carried out by relating above-ground carbon of tree components to DBH and height (H), using DBH and H as predictor variables. The best fit allometric models for above-ground carbon of total, stems, branches and twigs and/or leaves had coefficient of determination values (R2) of 0.98, 0.98, 0.96 and 0.79 respectively at P < 0.05. Above-ground carbon allometric models developed have wide application in sustainable use of the species and carbon accounting particularly in Central Zambezian Miombo woodlands without future destructive sampling.
  • Thumbnail Image
    Item
    Above-ground carbon stock in a forest subjected to decadal frequent fires in western Tanzania
    (International Network for Natural Sciences, 2017-02-14) Mganga, Nyatwere D.; Lyaruu, Herbert V.; Banyikwa, Feetham F.
    Gradual increase in atmospheric temperature due to elevated levels of greenhouse gases has become a global agenda. Of these gases, carbon dioxide is the most predominant accounting for more than half of the atmospheric warming. Conveniently, forests and woodlands are important sinks of carbon through sequestration which involves carbon dioxide capture and storage. Miombo woodlands are the most widespread savanna vegetation in the Sub-Saharan Africa, and like other vegetation they are likely to have a marked degree of carbon sequestration. However, these ecosystems are normally threatened by many disturbances, including outbreaks of uncontrolled and destructive fires. Yet, it has been reported that wildfires have both positive and negative influence on carbon sequestration in forests and woodlands. The aim of the present study was to determine tree carbon in Ilunde forest after consecutive exposure to frequent fires for 10 years. A fire suppressed forest of Kitwe was used as a control. Fire frequency of Ilunde forest was obtained from published Moderate Resolution Imaging Spectroradiometer (MODIS) satellite imagery from the year 2001 to 2012. Tree carbon stock was estimated using biomass allometric models so far developed for miombo woodlands.The level of difference in carbon density between the two forests was determined using t-test. Tree carbon stock was significantly high in Kitwe forest than in Ilunde (P < 0.05). The effects of wildfires are variable depending on the nature of ecosystems and the existing circumstances. Since fire is crucial in miombo woodlands, then prescribed burning could be prioritized to sustain sinks of carbon.
  • Thumbnail Image
    Item
    Determinants of Woody Cover in African Savannas
    (2005) Sankaran, Mahesh; Hanan, Niall P.; Scholes, Robert J.; Ratnam, Jayashree; Augustine, David J.; Cade, Brian S.; Gignoux, Jacques; Higgins, Steven I.; Le Roux, Xavier; Ludwig, Fulco; Ardo, Jonas; Banyikwa, Feetham F.; Bronn, Andries; Bucini, Gabriela; Caylor, Kelly K.; Coughenour, Michael B.; Diouf, Alioune; Ekaya, Wellington; Feral, Christie J.; February, Edmund C.; Frost, Peter G. H.; Hiernaux, Pierre; Hrabar, Halszka; Metzger, Kristine L.; Prins, Herbert H. T.; Ringrose, Susan; Sea, William; Tews, Jörg; Worden, Jeff; Zambatis, Nick
    Savannas are globally important ecosystems of great significance to human economies. In these biomes, which are characterized by the co-dominance of trees and grasses, woody cover is a chief determinant of ecosystem properties1, 2, 3. The availability of resources (water, nutrients) and disturbance regimes (fire, herbivory) are thought to be important in regulating woody cover1, 2, 4, 5, but perceptions differ on which of these are the primary drivers of savanna structure. Here we show, using data from 854 sites across Africa, that maximum woody cover in savannas receiving a mean annual precipitation (MAP) of less than ~650 mm is constrained by, and increases linearly with, MAP. These arid and semi-arid savannas may be considered ‘stable’ systems in which water constrains woody cover and permits grasses to coexist, while fire, herbivory and soil properties interact to reduce woody cover below the MAP-controlled upper bound. Above a MAP of ~650 mm, savannas are ‘unstable’ systems in which MAP is sufficient for woody canopy closure, and disturbances (fire, herbivory) are required for the coexistence of trees and grass. These results provide insights into the nature of African savannas and suggest that future changes in precipitation6 may considerably affect their distribution and dynamics.
  • Thumbnail Image
    Item
    Developing the Environmental Long-Term Observatories Network of Southern Africa (ELTOSA)
    (2003-04) Henschela, Joh; Pauw, Johan; Banyikwa, Feetham F.; Brito, Rui; Chabwela, Harry; Palmer, Tony; Ringroseg, Sue; Santos, Luisa; Sitoed, Almeida; Jaarsveld, Albert V.
    Background In May 2001, we, scientists from six countries in southern Africa, formed the Environmental Long-Term Observatories Network of Southern Africa (ELTOSA). Further development was made at the ELTOSA conference on Inhaca Island, Mozambique, during July 2002. ELTOSA connects country Environmental Observatories Networks (EON), the African adaptation of LTER (long-term ecological research). The International Long-Term Ecological Research Network (ILTER) has accepted ELTOSA as a regional member, and currently three ELTOSA country members have individual ILTER membership (Namibia in 1999, Zambia in 2001, South Africa in 2002) and others are working towards membership. This position paper describes the development of a vision for EON in southern Africa. We outline the importance of developing EON and list the opportunities this offers for the natural and social sciences. Finally, we focus on some challenges that accompany the development of EON in the region, with suggestions on how to meet them.
  • Thumbnail Image
    Item
    Developing the Environmental Long-Term Observatories Network of Southern Africa (ELTOSA)
    (2003) Henschel, Joh; Pauw, Johan; Banyikwa, Feetham F.; Brito, Rui; Chabwela, Harry; Palmer, Tony; Ringrose, Sue; Santos, Luisa; Sitoe, Almeida; van Jaarsveld, Albert
    In May 2001, we, scientists from six countries in southern Africa, formed the Environmental Long-Term Observatories Network of Southern Africa (ELTOSA). Further development was made at the ELTOSA conference on Inhaca Island, Mozambique, during July 2002. ELTOSA connects country Environmental Observatories Networks (EON), the African adaptation of LTER (long-term ecological research). The International Long-Term Ecological Research Network (ILTER) has accepted ELTOSA as a regional member, and currently three ELTOSA country members have individual ILTER membership (Namibia in 1999, Zambia in 2001, South Africa in 2002) and others are working towards membership. This position paper describes the development of a vision for EON in southern Africa. We outline the importance of developing EON and list the opportunities this offers for the natural and social sciences. Finally, we focus on some challenges that accompany the development of EON in the region, with suggestions on how to meet them.
  • Thumbnail Image
    Item
    The Distribution and Socio-Economic Aspects of Mangrove Forests in Tanzania
    (1986) Mainoya, J. R.; Mesaki, Simeon; Banyikwa, Feetham F.
    Mangrove vegetation is characteristic of sheltered coastlines in the tropics. Mangrove communities are extensive in protected shallow bays and estuaries, around lagoons, and on the leeward side of peninsulas and islands. In Tanzania mangrove forests occur on the sheltered shores of deltas, alongside river estuaries, and in creeks where there is an abundance of fine-grained sediment (silt and clay) in the upper part of the inter-tidal zone.
  • Thumbnail Image
    Item
    Ecosystem Catalysis: Soil Urease Activity and Grazing in the Serengeti Ecosystem
    (Wiley, 1997) McNaughton, S. J.; Zuniga, Gina; McNaughton, M. M.; Banyikwa, Feetham F.
    The activity of soil ureases was evaluated in the laboratory in soils from three locations in the Serengeti National Park, Tanzania, differing in the grazing intensities that the grasslands there support. Urease activity was assayed by the instantaneous release of NH4 as soon as soils drained to field capacity after application of an aqueous urea solution approximating N concentrations in ungulate urine. The appearance of NO3 and S04 in extracts was used as an index of biological activity and pH changes; neither responded to urea addition. Ammonium appearance in extracts of soils to which water but not urea was applied was low and identical; appearance in extracts where urea had been added was high and differed between sites, increasing with the level of grazer activity at a site. The data document ecologically meaningful levels of soil urease in Serengeti soils and a positive associa- tion of those levels with grazing intensity.
  • Thumbnail Image
    Item
    Ecosystem Catalysis: Soil Urease Activity and Grazing in the Serengeti Ecosystem
    (1997) McNaughton, S. J.; Zuniga, Gina; McNaughton, M. M.; Banyikwa, Feetham F.
    The activity of soil ureases was evaluated in the laboratory in soils from three locations in the Serengeti National Park, Tanzania, differing in the grazing intensities that the grasslands there support. Urease activity was assayed by the instantaneous release of NH4 as soon as soils drained to field capacity after application of an aqueous urea solution approximating N concentrations in ungulate urine. The appearance of NO3 and SO4 in extracts was used as an index of biological activity and pH changes; neither responded to urea addition. Ammonium appearance in extracts of soils to which water but not urea was applied was low and identical; appearance in extracts where urea had been added was high and differed between sites, increasing with the level of grazer activity at a site. The data document ecologically meaningful levels of soil urease in Serengeti soils and a positive association of those levels with grazing intensity.
  • Thumbnail Image
    Item
  • Thumbnail Image
    Item
  • Thumbnail Image
    Item
    Fuzzy Set Ordination and Classification of Serengeti Short Grasslands, Tanzania
    (Wiley, 1990) Banyikwa, Feetham F.; Feoli, Enrico; Zuccarello, Vincenzo
    Species abundance data from 32 representative stands are used to evaluate the vegetation in the heavily grazed Serengeti short grasslands. The abundant species are: Kyllinga nervosa, Sporobolus ioclados, S. kentrophyllus and Eustachys paspaloides, all occurring in elevated areas, and Hypoestes forskalei, which is found in the drainage areas. Numerical classification and fuzzy set ordination revealed four main grassland communities associated with a topographic gradient. The communities are considered distinct since their niches, as computed in the community and environmental fuzzy system space are not overlapping. Leaching, erosion and animal disturbance effects correlated with the topographic gradient are found to determine species composition and overall community structure in the grasslands.
  • Thumbnail Image
    Item
  • Thumbnail Image
    Item
  • Thumbnail Image
    Item
    The Growth Response of Two East African Perennial Grasses to Defoliation, Nitrogen Fertilizer and Competition
    (1988) Banyikwa, Feetham F.
    Two East African perennial grasses, Digitaria macroblephara (Hack) Stapf. and Sporobolus ioclados (Trin.) Nees, were grown in pure and mixed culture in a factorial treatment design of defoliation, nitrogen fertilizer and plant density for a period of 90 d. With regard to controls, defoliation reduced total yield of both species per plant by 81%; higher density decreased total yield per plant by 56%; and intraspecific competition decreased total yield per plant 24% more than interspecific competition. High nitrogen promoted total yield per plant by 168%. Total yield per plant of D. macroblephara was 3.2 times greater than that of S. ioclados. With defoliation, density dependent competition decreased total yield per plant by 42% while, without defoliation, density dependent competition decreased total yield per plant by 601%. With defoliation, high nitrogen increased yield per plant by 9% while without defoliation high nitrogen increased yield per plant by 315%. The results suggest that the magnitude of the negative aspects of density dependent competition may be lessened by defoliation and growing plants in mixed culture. It is concluded that in grazing ecosystems it may be advantageous to grow plants in mixed culture since the negative effects of interspecific competition are less than those arising from intraspecific competition.
  • Thumbnail Image
    Item
    The Growth Response of Two East African Perennial Grasses to Defoliation, Nitrogen Fertilizer and Competition
    (Wiley, 1988) Banyikwa, Feetham F.
    Two East African perennial grasses, Digitaria macroblephara (Hack) Stapf. and Sporobolus ioclados (Trin.) Nees, were grown in pure and mixed culture in a factorial treatment design of defoliation, nitrogen fertilizer and plant density for a period of 90 d. With regard to controls, defoliation reduced total yield of both species per plant by 81%; higher density decreased total yield per plant by 56%; and intraspecific compe- tition decreased total yield per plant 24% more than interspecific competition. High nitrogen promoted total yield per plant by 168%. Total yield per plant of D. macro- blephara was 3.2 times greater than that of S. ioclados. With defoliation, density dependent competition decreased total yield per plant by 42% while, without defolia- tion, density dependent competition decreased total yield per plant by 601%. With defoliation, high nitrogen increased yield per plant by 9% while without defoliation high nitrogen increased yield per plant by 315%. The results suggest that the magni- tude of the negative aspects of density dependent competition may be lessened by defoliation and growing plants in mixed culture. It is concluded that in grazing ecosystems it may be advantageous to grow plants in mixed culture since the negative effects of interspecific competition are less than those arising from intraspecific competition.
  • Thumbnail Image
    Item
    Loss of Ascorbic Acid Due to Wilting in Some Green Leafy Vegetables
    (1983) Seeramulu, N.; Banyikwa, Feetham F.; Srivastava, V.
  • Thumbnail Image
    Item
    Optimal Weeding Period for Groundnuts (Arachis Hypogea L.)
    (1988) Rulangaranga, Z. K.; Banyikwa, Feetham F.
  • Thumbnail Image
    Item
    The Physical and Chemical Characteristics of a Phycocolloid from the Red Alga Sarcodia Montagneana j. Agardh of Tanzania
    (1987) Semesi, A. K.; Banyikwa, Feetham F.
    A phycocolloid from Sarcodia montagneana has been evaluated by chemical and physical analyses. The study has revealed that the phycocolloid has a yield of 39.6 per cent (percentage dry weight of alga), an IR spectrum similar to that reported for .lambda.-type carrageenan, an SO4-2 content of 22.5 per cent, a 3, 6-anhydrogalactose content of 5.1 per cent, a galactose content of 51.5 per cent (percentage dry weight of phycocolloid) and a negative optical rotation. The polysaccharide does not form a gel and cannot be modified by alkaline borohydride. It may be used in the food industry as an emulsifying agent.
  • Thumbnail Image
    Item
    Plant Communities and Herbivory
    (1995) McNaughton, S. J.; Banyikwa, Feetham F.
  • Thumbnail Image
    Item
    Promotion of the Cycling of Diet-Enhancing Nutrients by African Grazers
    (1997) McNaughton, S. J.; Banyikwa, Feetham F.; McNaughton, M. M.
    Experiments in Serengeti National Park, Tanzania, provide direct evidence that large, free-ranging mammalian grazers accelerate nutrient cycling in a natural ecosystem in a way that enhances their own carrying capacity. Both nitrogen and sodium were at considerably higher plant-available levels in soils of highly grazed sites than in soils of nearby areas where animal density is sparse. Fencing that uncoupled grazers and soils indicated that the animals promote nitrogen availability on soils of inherently similar fertility and select sites of higher sodium availability as well as enhancing that availability.