Browsing by Author "Rija, A. A."

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Activity patterns and fine-scale resource partitioning in the gregarious Kihansi spray toad Nectophrynoides asperginis in captivity
(Wiley & Sons, 2014-08-01) Rija, A. A.; Goboro, E. M.; Mwamende, K. A.; Saidi, A.; Kohi, E. M.; Shombe, H. N.
Understanding the behavior of species threatened with extinction is important for conservation planning and for solving problems facing species in captivity and the wild. We examined diurnal activity budgets and habitat use of the extinct in the wild Kihansi spray toad to provide insights into ongoing conservation initiatives for this species. Observations on eight target behaviors were made each morning and evening for 14 days, in two subpopulations at Kihansi and University of Dar es Salaam captive breeding centers. There were significantly more bouts of resting than calling, amplexing, hunting, walking, climbing, or feeding. There was no difference in mean time spent in each activity between the two subpopulations. The use of habitat was variable between age classes, subpopulations and sampling time. Young toads spent significantly more time resting at the top of vegetation and on walls while adults rested
The aftermath of environmental disturbance on the critically endangered Coffea kihansiensis in the Southern Udzungwa Mountains, Tanzania
(Sagepub.com, 2011-01-01) Rija, A. A.; Shombe, H. N.; Mwamende, K. A.
The endemic Coffea kihansiensis was monitored in the Kihansi gorge over a three year period following diversion of the Kihansi River underground for hydropower production and its associated catastrophic effect on the gorge biota. We assessed the growth status of the coffee population by measuring, along an altitudinal gradient, the height and diameter of 450 randomly selected coffee stems in 18 sampling plots covering ca 1800 m2. We also collected microclimatic data to compare with that collected prior to river diversion. Coffee infestation by parasites was examined by recording the number of stems with signs of infestation. There was no significant change in size of Coffea kihansiensis during the study period. However, the size for immature plants differed between the two sites; LWF and UCF. Parasite infestation differed between reproductive age classes and was greater at lower elevation (800 – 850 m a.s.l …
Assessment of fire prevalence and reduction strategies in Miombo woodlands of Eastern Tanzania
(African Journals Online, 2014-12) Katani, J. Z.; Madoffe, S.S.; Amanzi, N. S.; Amanzi, N. S.; Rija, A. A.; Midtgaard, F.; Mbeyale, G. E.; Zahabu, E.; Tarimo, B. C.
An assessment of the proximate causes, effects and factors contributing to fire prevalence was conducted in three districts covered by miombo woodlands in Eastern Tanzania. Three miombo woodlands under different management regimes and governance structures (central government forest reserve, local government forest reserve and village land forest) each were investigated in Handeni, Kilosa and Kilwa districts. Data were collected from three villages selected in each District through household surveys, Participatory Rural Appraisal (PRA), interviews of key informants and field observations. The analysis of data involved content analysis for documentary materials, descriptive statistical analysis for household surveys and Chi square was used to test whether there were differences in responses of local communities across forest management regimes. Results indicate that the major five human activities contributing to fire prevalence across the miombo woodlands include farm preparation (34.1%), hunting (28.5%), arson (21.5%), livestock grazing (9.3%) and charcoal making (0.7%). The causes were fairly the same across forest management regimes. August, September and October were the peak fire months and they were not influenced by different management regimes but by geographical locations within Eastern Tanzania. Results further show that fires in miombo woodlands usually start inside the woodland (67.2%), around residential area (22.9%) and from farms (9.9%). The origin of fire inside the woodland becomes more serious because it combines the hunting, arson, livestock grazing and charcoal making which are usually done inside the woodland. Chi-square test indicates significant difference on origin of fires across the forest management regimes (χ² = 13.341 and p = 0.031). The local communities acknowledged fires having both positive and negative effects and these effects were the same across the management regimes. Further, across the surveyed villages, strong social ties existed between fires and the daily life of local communities. Poverty, ignorance, weak law enforcement and climatic factors were identified as underlying factors contributing to fire prevalence. Fire incidences are predicted to increase given the increasing climate change. Potential strategies to reduce fires incidence identified were awareness creation, law enforcement, making fire breaks, introduction of alternative income generating activities, and improving agriculture practises. Furthermore, the use of prescribed burning to reduce effects of late fires and developing fire management plans to enhance miombo woodland management are among the strategies worth consideration by the local communities.
Composition and Functional Diversity in Bird Communities in a Protected Humid Coastal Savanna
(Hindawi Publishing Corperation, 2015-04) Rija, A. A.; Mgelwa, A. S.; Modest, R. B.; Shombe, H. N.
Our current understanding of the vertebrate communities of a newly gazetted Tanzanian coastal national park is limited and strongly taxonomically biased towards large mammals. We conducted bird assessments in three sites in Saadani National Park using species lists to analyze some parameters to inform biodiversity conservation in the area. We recorded 3112 individuals in 268 species falling in 66 families, including 2 endangered, 2 vulnerable, and 6 near threatened species. Both species richness and species diversity varied between sites. Species relative abundances were not different between the sites although some functional groups, especially granivores, were more abundant than others. Bird assemblages included 21 forest specialists (FF-species), 35 forest generalists (F-species), and 68 forest visitors (f-species) overlapping among bushland, wooded grassland, grassland, and thickets suggesting presence of important microhabitats for the forest-associated species in this ecosystem. Bird species richness in a feeding guild also showed marked overlap between habitats suggesting availability of rich food resources for the birds. This paper highlights the importance of maintaining a structurally heterogeneous landscape to sustain diverse bird communities in the area.
Developing Fire Reduction Strategy for Miombo Woodlands as a Potential tool for Carbon Storage and Sequestration
(E&D Vision Publishing Ltd, 2016) Katani, J. Z.; Modoffe, S.S.; Midtgaard, F.; Rija, A. A.; Amanzi, N. S.; Kilawe, C.J.; Mbeyale, G. E.; Zahabu, E.; Tarimo, B. C.; Silayo, D.S. A.
World-wide, wildfires cause problems and when uncontrolled or misused they wreak havoc on society and the environment. In Tanzania, fire occurs in most parts of the Miombo woodlands, and some of them cause significant eco-logical and socio-economic impacts. Several efforts have been made in Tanzania to reduce the occurrence of fire in Miombo but their success has been constrained by underfunding and/or lack of proper strategies. Moreover, in many districts of Tanzania there are no apparent solutions to the fire problem, despite years of regulation and attempts to control fire, and in many places fire incidences are actually increasing. Therefore, this study intended to develop a fire management strategy for the Miombo woodland as a tool for climate change mitigation. This study also strived to identify causes, effects and factors contributing to fire prevalence. Spatial and temporal distribution of fires and burnt extents of wooded areas were determined from the Moderate Resolution Imanging Spectroradiometer (MODIS) active fires product and Landsat satellite images for the past 40 years (1972–2012). Vegetation and household surveys were used to capture empirical data on carbon stock and how different burning regimes and forest management scenarios influence carbon sequestration potentials. Furthermore, the role of formal and informal framework for the prevention, control and management of wild fires in the Miombo was determined. Th main output of this study is a proposed fire reduction strategy in Miombo. Th study findings show that, to a wider extent, 1.8 and 2.9 years mean fire return interval persist in western and eastern dry Miombo areas, respectively, burning up to 50.6% of the woodland. These wildfires were largely human-driven and commonly occur in all the villages surveyed whereas the existing local governance structures and institutions suffered from poor coordination, severe underfunding and poor support from the villagers. Torching of forests was largely perpetuated by weak enforcement of laws and regulations, poverty and existing local beliefs. On average, there is an indication that the central government forests have higher stock of carbon than the local government forests and village government forest reserves. However, there was no significant difference in carbon stock between forests experiencing no burning, early burning and late burning. The proposed fire management strategy for Miombo woodlands focused on the promotion of sustainable alternative land preparation methods, improved household income sources and awareness, sustainable land use management and promotion of sustainable charcoal production. The strategy indicates a number of activities to be implemented and actors responsible for each activity.
Emerging issues and challenges in conservation of biodiversity in the rangelands of Tanzania
(Pensoft Publishers, 2013-11-18) Rija, A. A.; Kideghesho, J. R.; Rija, A. A.; Kideghesho, J. R.; Mwamende, K. A.; Selemani, I.
Tanzania rangelands are a stronghold for biodiversity harbouring a variety of animal and plant species of economic, ecological and socio-cultural importance. Efforts to protect these resources against destruction and loss have involved, among other things, setting aside some tracks of land as protected areas in the form of national parks, nature reserves, game reserves, game controlled and wildlife management areas. However, these areas and adjacent lands have long been subjected to a number of emerging issues and challenges, which complicate their management, thus putting the resources at risk of over exploitation and extinction. These issues and challenges include, among other things, government policies, failure of conservation (as a form of land use) to compete effectively with alternative land uses, habitat degradation and blockage of wildlife corridors, overexploitation and illegal resource extraction, wildfires, human population growth, poverty, HIV/AIDS pandemic and human-wildlife conflicts. In this paper, we review the emerging issues and challenges in biodiversity conservation by drawing experience from different parts of Tanzania. The paper is based on the premise that, understanding of the issues and challenges underpinning the rangelands is a crucial step towards setting up of plausible objectives, strategies and plans that will improve and lead to effective management of these areas. We conclude by recommending some proactive measures that may enhance the sustainability of the rangeland resources for the benefit of the current and future generations.
Fire history and management as determinant of patch selection by foraging large mammal herbivores in western Serengeti, Tanzania
(Taylor & Francis, 2011-09-30) Rija, A. A.; Shombe, H. N.
Although the use of fire as a management tool has increased during the past decades in East African savannas, there is insufficient knowledge about herbivores' utilization of areas with different fire history. We therefore examined large mammal herbivores' preference for patches that differed in fire history to test whether herbivores would non-randomly select patches according to availability. Our study area was the East African Serengeti ecosystem. Animals were recorded along transects at monthly intervals from May 2001 to April 2006, and data on the burnt and non-burnt areas along transects were extracted from existing fire maps. The prediction was tested using chi-square goodness-of-fit test, and selection ratio as a preference index for patch types. Our results show that African buffalo persistently occurred in non-burnt patches, whereas browsers (Giraffe and Kirk's dik-dik) and mixed feeders (Grant's gazelle …
Floss release, seed fall and germination of Ceiba pentandra in an urban environment
(Scientific Research Publishing, 2013-09-25) Rija, A. A.; Saidi, A.; Mwita, J.; Mwamende, K. A.
The tropical forest kapok tree occurs widely in urban environments, dispersing thousands of floss during the fruiting season. However, its seedlings are rarely seen around human settlements, raising questions on what factors might be limiting its recruitment. We examined the pattern of floss release, seed fall post-dispersal and influences of watering frequency on germination of Ceiba pentandra seeds. Evening, overall, was associated with a significantly higher rate and quantity of floss release (p= 0.0001) than were mid-day and morning, correlating well with the speed of wind across the day (rh= 0.666, p= 0.001). Mean dispersal quantity differed significantly between the individual sampled trees, in which the highest dispersal was recorded from trees located in relatively open areas and the lowest was recorded in closed stand trees. Seed fall was higher within 100 m distances than seed fall farther away from dispersing trees, depending on the microsites and weather conditions. Germination started on day 5 onwards and only 15.67% of sown seeds germinated. Watering frequency strongly influenced seed germination while local human activities determined fate of dispersed seeds. We conclude that recruitment of C. pentandra species in the study area may have been limited by environmental and human factors operating at various local and spatial scales.
Incentives for conserving and greening our cities
(Ministry of Natural Resources and Tourism-Tanzania, 2010-11-09) Rija, A. A.
Modeling black rhinoceros (Diceros bicornis) population performance in East Africa: the case of Lake Nakuru National Park, Kenya
(2014-03-06) Rija, A. A.; Soka, G. E.; Owino, A.
The black rhinoceros have declined across Africa both in numbers and range distribution, making long-term population persistence of this iconic species uncertain. We conducted simulation models to predict population performance of black rhinoceros in Lake Nakuru National Park under different scenarios of environmental variation and translocation regimes. A decade-long (1987-1997) demographic data were used to construct stochastic simulation models using VORTEX computer program. In addition, we assessed extinction risks and patterns of heterozygosity among the modelled populations (reported every five years) to characterize the dynamics of this population over a hundred years. The population of black rhinoceros showed varying patterns of fluctuations under different scenarios. The best-case scenario showed a considerable increase in the modelled population with the population attaining the highest growth (population growth (λ)= 1.04) after 40 years. The mean final population size for the successful cases was 70.85±2.0 animals, which was relatively close to the carrying capacity used in the simulation. The expected heterozygosity was 0.912±0.02 suggesting that the remaining population may be genetically viable. Further, environmental variation of 1-2% magnitude across the various age categories, and without translocation, had no significant effect on the deterministic growth rate of the population. Maintaining the translocation of 2 males and 2 females on yearly basis would significantly boost and sustain the population of black rhinoceros in the study area.
Notes on Feeding Habits of Spider Nephila sp in an Acacia woodland stand, Kenya
(biological research, 2012-10-06) Rija, A. A.; Mwamende, K. A.; Shombe, H. N.
AIM: To investigate the feeding habits of the spider Nephila sp and document its behavioural and ecological aspects in its natural environment. METHODS: The study was carried out in Naivasha, Kenya within the Elsamere Field Study Centre (EFSC) compound located on the southern waterfront of Lake Naivasha. We used field surveys of insects and food selectivity model to record the dietary spectrum of the spider as well as examined spider selectivity behaviour for various prey. Also, field feeding experiments were used to test whether Nephila, in its natural environment, catches trapped prey according to taxon and weight and whether prey distance from the spider determines capture in the web. RESULTS: The spider's dietary items constituted five Orders of insects, with the predator showing highest selectivity for Hymenoptera, Diptera and Coleoptera. Prey captured by the webs were significantly fewer than those available to the spider. On the average however, 1.4 insects per web spider per day were available as food for the spiders in the area, perhaps accounting for the localized and densely observed spiders. Also, distance had greatest influence on prey capture by the spider while prey weight and taxon were less important factors. These factors may have played important regulatory function in optimizing spider’s foraging success in the web. CONCLUSION: This study provides insights into understanding the behavioral and ecological aspects of the spider in the natural environment. More research done under indoor controlled environment could reveal more insights into the behavioural repertoire of this species.
Population density estimates of some species of wild ungulates in Simanjiro plains, northern Tanzania
(Wiley Online Library, 2011-02-09) Rija, A. A.; Shombe, H. N.
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Preliminary Assessment of Forest Structure, Management and Carbon Stocking in Tanzania Miombo Woodland
(Climate Change Impacts, Mitigation and Adaptation Programme, SUA, 2012) Madoffe, S. S.; Rija, A. A.; Midtgaard, F.; Katani, J. Z.; Mbeyale, G. E.; Zahabu, E.; Christopher, B.
Wildfires are critical in miombo forests across the African continent causing loss of biodiversity, human properties and increasing climate change impacts. Within a broader project which seeks to develop a strategy to reduce wildfires in miombo woodlands of Tanzania, we report on the preliminary findings based on initial field data collected in situ to set a baseline for further work. The project covers three miombo biomes in three districts (Handeni, Kilosa and Kilwa) in Eastern Tanzania covering nine forest reserves managed under different authorities namely, central government, local districts and village communities. The aim of the current study were therefore, to describe species composition and structure of the forest communities, profile initial carbon stock in trees, herbaceous layer and soil within permanent survey plots, in effort to examine the potential of using fire reduction strategy as a potential tool of carbon sequestration in miombo woodlands.. The research team used permanent forest plots to collect vegetation and soil data. Simlarly available models were used to estimate carbon stocking. More than 200 species of trees and shrubs totaling 506 individual trees (dbh >4 cm) were recorded and Kilosa site contributed the largest proportion (40.7%) to the tree abundance total. This was followed closely by Kilwa (35.6%) and Handeni (20.7%). Species richness and diversity varied considerably within and between the study sites. Kilwa had the highest species richness and Handeni the lowest. Analysis of community assemblages revealed strongly distinct forest communities both at local and regional level between Kilwa and other sites. Carbon stocks in trees and soil were significantly different among sites and were higher than previously reported for other miombo woodland elsewhere in Tanzania. On the average tree carbon ranged from 21.42-44.12t/ha, the highest stock reported in Kilosa site due to assemblage of large trees. The general picture of carbon stock indicated that early burning is better for carbon storage than late burning or no burning. The lack of fire reduction strategy overrides the dynamics of forest stand structure and the potential for carbon sequestration by these forests as wildfires appear to be critical across the study area. There is dire need for a comprehensive strategy to reducing forest fires across the miombo biomes which together will help mitigate climate change impacts in Tanzania.
The risks of relocating wildlife
(Ministry of Natural Resources and Tourism-Tanzania, 2010-10-21) Rija, A. A.
The role and performance of existing governance structures in prevention and management of wildfires in Miombo woodland, Tanzania
(CCIAM-SUA, 2014) Rija, A. A.; Madoffe, S. S.; Katani, J. Z.; Amanzi, N. S.; Midtgaard, F.; Zahabu, E.; Tarimo, B. C.; Mbeyale, G.
Although wildfire remains a persistent threat to the forest resources and human livelihood, very limited information exists about the role and performance of existing local governance structures in the prevention and management of wildfires in Miombo woodlands. This study was conducted in nine villages of Handeni, Kilosa and Kilwa Districts, eastern Tanzania to examine how existing local governance structures were actively involved in prevention of wildfires in forests under differing management regimes. All the surveyed villages had both formal and informal governance structures responsible for prevention and management of wildfires with over 50% of respondents aware of their existence. Available formal structures included village councils, Village Environmental Committees (VEC)/Village Natural Resource Committee (VNRC), ward development committees and primary courts. These structures were charged with ensuring security in the respective villages including protecting forests against deforestation and degradation. Despite their existence in every village, most suffered poor coordination, severe under funding and poor support from the villagers who see torching of forests as their sole right to getting access to their livelihoods. The study established that existing local fire management structures are unlikely to guarantee effective prevention of this environmental threat unless the existing impediments are effectively addressed. Management of forest fires should therefore be handled through a well coordinated framework that accommodates all key stakeholders in the country and should empower existing local fire prevention machinery
Spatial metrics effect of forest fragmentation on forest bird abundance and site occupancy probability: the influence of patch size and isolation
(Taylor & Francis, 2016-05-20) Robert, M. B.; Shombe, H. N.; Rija, A. A.
The persistence of species taxa within fragmented habitats is dependent on the source–sink metapopulation processes, and forest patch size and isolation are key factors. Unveiling species–patch area and/or species–patch isolation relationships may help provide crucial information for species and landscape management. In this study, relationship between forest patch size and isolation with abundance and occupancy probability of forest-dependent birds was investigated. This study was based within a coastal landscape that faces deleterious human activities such as clearing for agriculture. The study aimed to answer the question of whether the size and extent of isolation of forest patches influence abundance and/or occupancy probability of forest-specialist and generalist birds. Two bird species, namely Tiny Greenbul Phyllastrephus debilis subsp. rabai and Yellow-bellied Greenbul Chlorocichla flaviventris …
Species Richness and Diversity Reveal that Human-Modified Environments are not Wastelands
(African Journals Online, 2014-08) Rija, A. A.; Kimario, A.; Shombe, H. N.
Urbanization is often associated with the loss of habitats for many species but the pattern of invertebrate abundance in increasingly human-dominated urban areas is less well documented particularly for the expanding urban Africa. This study investigated the composition and community structure of spiders in relation to human activities at the foot of the Uluguru Mountains in Morogoro city, Tanzania. Three different sampling methods: pitfall trapping, sweep netting and active searching were used to collect spiders in the study area and to allow comparison between structurally different habitat sites. Spider abundance differed significantly
Urban sprawl and species movement may decimate natural plant diversity in an Afro-tropical city
(Springer Netherlands, 2014-04-01) Rija, A. A.; Said, A.; Shombe, H. N.; Mwamende, K. A.; Madoffe, S. S.
Although urban sprawl is increasingly becoming a worldwide problem, the effects associated with urbanization on local biodiversity particularly in the developing countries, is still poorly understood. We investigated plant species richness along urban–rural gradients in an Afro-tropical metropolitan Morogoro city in Tanzania, and examined patterns of species movement by humans within and outside the city and its potential impact on habitat homogenization of urban ecosystems. Biodiversity information was assessed in 120 sample plots (25 × 25 m) distributed in core urban, sub-urban and peri-urban (rural) zones, while patterns of plant resource use and species movement were surveyed from 120 households in the study area. We found the highest tree species richness in the urban core (82.6 ± 1.4 species) whereas tree density decreased from peri-urban (465.60 ± 152.03 tree/ha) to urban core (244.00 ± …