Influence of Seasonality and Eucalyptus Plantation Types on the Abundance and Diversity of Litter Insects at the Arboretum of Ruhande in Southern Rwanda

The aim of this study was to document on the influence of seasonal variability and Eucalyptus plantation types on the abundance and diversity of litter insects using the Arboretum of Ruhande in Rwanda. Insect individuals were sampled and fixed in a 10% formalin solution, and brought to the laboratory for identification to order and family levels. Insect individuals were classified in 9 orders and 27 families. Coleoptera and Hemiptera orders were the most diversified with eight families each. The results indicated that the order Hymenoptera showed the highest abundance in all seasons, followed by Coleoptera, Hemiptera, and Isoptera orders. Results indicated that stands of four Eucalyptus species have litter insect diversity which was higher than that of native Entandrophragma excelsum which was set as a reference. Insects abundance combined with Shannon diversity indices in different seasons indicated that stands of Entandrophragma excelsum, Eucalyptus grandis, Eucalyptus maidenii and Eucalyptus saligna have the best conditions for the establishment of diverse insects in the litter. Therefore, negative ecological effects of Eucalyptus species on insect biodiversity may not be exclusively attributed to the whole genera. Seasonal variation of litter insect diversity indicated that dry season (September 2012) had the highest Shannon diversity indices relative to those in rainy seasons (January and April 2013). This indicates that heavy rain negatively impact the survival and diversity of litter insects. High variability of litter insects is attributed to the variability of habitat conditions, including understory vegetation, litter cover, and soil chemistry. Further studies on seasonal variation of litter insects in other Rwandan ecological regions are needed. Keywords: Entandrophragma; Eucalyptus; Insects; Hymenoptera; Seasonal variation

Effects of management practices on soil organic matter content, soil microbial activity and diversity in the KwaZulu-Natal midlands.

Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2002.The objective of this study was to investigate the effects of land use and management practice on the soil organic matter content and the size, activity and diversity of the microbial biomass. These effects were investigated using samples taken from the top (0-10 cm) layer of the soils from long-term agricultural managements including natural grassland, maize under conventional (maize CT), maize under zero tillage (maize ZT), annual ryegrass, Eucalyptus, Pinus, and permanent kikuyu pasture. The natural grassland was used as a control since records indicated that no agricultural activity had ever been exerted on the soil. The measurements used to investigate these effects included soil organic C, total N, soil pH, microbial biomass C, basal respiration rate, microbial quotient, metabolic quotient, dehydrogenase activity, fluorescein diacetate (FDA) hydrolysis, arginine ammonification rate, arylsulphatase activity and acid and alkaline phosphatase activities. The microbial functional diversity was measured using the Biolog Ecoplate and catabolic response profiles methods. Soil organic Cand total Nwere lowest under maize CT, followed by maize ZT and annual ryegrass and were higher under natural grassland, Eucalyptus and Pinus plantations while permanent kikuyu pasture had the highest values. The other analyses, namely microbial biomass C, basal respiration rate, FDA hydrolysis, arginine ammonification rate and arylsulphatase activity also followed the same pattern. Annual cultivation was responsible for a decrease in microbial biomass C, basal respiration rate and enzyme activity, principally because there was an appreciable decrease in soil organic matter content. Conversely, permanent pasture, Eucalyptus and Pinus plantations increased appreciably the amount of organic C and consequently, promoted the size and activity of the microbial biomass in the soils. The principle component scores showed that management practices affected the microbial functional diversity because different treatments were found in separate zones of the principle component spaces. The regression analysis showed that the variation in the PC1 and PC2 scores was correlated with the variation in soil organic C, exchangeable acidity, extractable P and exchangeable K and Mg. In addition, richness, evenness, Shannon, and Simpson diversity indices showed that any management practice affects the dynamics of soil microbial diversity

Seasonal variation of litter arthropods in some Eucalyptus plantations at the Arboretum of Ruhande in Rwanda

The main objective of this study was to assess the seasonal variation of litter arthropods in seven Eucalyptus plantation types and native Entandrophragma excelsum stands at the Arboretum of Ruhande, Rwanda.  Arthropods were collected using the 1m2 square pick–up point technique, killed using 10% formalin solution, and transported to the laboratory for identification to the class level. The results indicate that the collected arthropod individuals belong to five classes. Seasonality exerted a strong effect on the abundance and diversity of litter arthropods. In total, 2828 arthropod individuals were collected in September 2012, 3458 individuals in January 2013 and 4005 individuals in April 2013. The Class of insects was the most abundant with relative frequency of 54.8%, 77.3% and 76.6% in September 2012, January 2013, and April 2013 sampling periods. The negative effect of Eucalyptus plantations on arthropods abundance was not exclusively confirmed by the results as some stands of Eucalyptus species had arthropod abundance comparable to those under native Entandrophragma excelsum stands. It is recommended to replicate this study under forest plantations located in other ecological zones in Rwanda, which will generate general information for better conservation of arthropod diversity in Rwanda. It is also recommended to continue arthropod classification at family, genus and species levels. Keywords: Litter arthropods; Arthropod abundance; Arthropod diversity

Land transaction in peri urban areas of Kigali city: a case study of Ndera sector (Gasabo District)

Slide presentation given at the 3rd IPAR Annual Research Conference, 13-14 November 2013

Water Physico-Chemical Characteristics of the Lakes Burera and Ruhondo, Rwanda

Rwanda possesses multiple lakes, whose properties were rarely described. The present study assessed physico-chemical characteristics of water in Burera and Ruhondo lakes located in highly populated area with steep slopes, which are under extensive agriculture, thus water quality monitoring is important. Both lakes were alkaline with high content of Mg, while Ruhondo had higher electrical conductivity than Burera. Phosphorus and nitrogen exceeded Class III EPA standards indicating that both lakes are at risk of eutrophication. Keywords: water quality, lakes Burera and Ruhondo, Rwand

The process of institutionalization-deinstitutionalization and children’s psychological adjustment in Rwanda:: Parents matter

Negative effects of institutionalization and positive effects of deinstitutionalization on children’s wellbeing have been well documented. However, the majority of reports on institutional care rely on adult interviews and there is a wide disparity of results and methodologies in few result-oriented studies of deinstitutionalization outcome. In addition, though all over the world, especially in developed countries, many children in orphanage have parents; little is known about on the effect of having or not living biological parents and be institutionalized. The present thesis aims generally to investigate whether institutionalization negatively impacts the psychological adjustment of children. Specifically, this thesis aims at (1) exploring children’s perceptions on institutionalization process; (2) investigating the influence of biological parental living status on institutionalized children’s psychological adjustment; and (3) evaluating the effectiveness of deinstitutionalization as well as conditions for better psychological adjustment once children are deinstitutionalized. With a prospective longitudinal comparative design, focus group discussions and self-report questionnaires were used by the present thesis to collect respectively qualitative and quantitative data from 177 children aged 9 to 16 and their parents/primary caregivers divided in 6 registered orphanages and 5 primary schools in Rwanda. Grounded theory was used to analyze qualitative data whilst analysis of variance and multiple regression were used to analyze quantitative data. Outcome variables included externalizing and internalizing behavior, attachment and self-esteem. Taken together, our results show that institutionalization has a negative impact on children’s psychological adjustment. The most remarkable and unexpected finding is that Rwandan children living in institution have more impairment in psychopathological symptoms when they have living parents. They considered institutionalization as an orphanization process. Another remarkable finding is that the present thesis failed to prove the improvement of psychological adjustment due to de-institutionalization in all domains as expected. The improvement was reported in attachment while no change was observed in externalizing behavior or self-esteem after deinstitutionalization and worse, internalizing behavior worsened among de-institutionalized children. Family relationships and parenting involvement were reported to be the strongest predictors of children’s psychological adjustment in most of measured outcome variables. Unexpectedly, socioeconomic status, didn’t gain as much importance in that prediction. Contrariwise, adult’s perceived quality of life was a significant mediated predictor in children’s externalizing behavior and had a moderating effect in children’s internalizing behavior. This should be considered to develop and improve supportive specific interventions for children and considered when making the decision of placing or not a child with parents in an institution. Results suggest the intensification of identifying and addressing the behavioral problems as part of deinstitutionalization process focusing also on family characteristics to improve children’s psychological adjustment. Moreover, understanding the development of psychopathological problems during the process of institutionalization and de-institutionalization may be key to preventing high costs associated with these disorders across the life course

Examining coffee export performance in Eastern and Southern African countries: do bilateral trade relations matter?

This study examines the impact and implications of the East African Community and the Common Market for Eastern and Southern Africa preferential trade agreements on coffee export performance of eight East and Southern African countries. The analysis employed a static and dynamic gravity modelling framework for the period 1998-2013. Following several robustness checks, the study found that regional trade agreements play a vital role in increasing coffee trading in East and Southern African countries. Factors including geographical distances, income, and population size in importing and exporting countries are also statistically significant determinants of coffee exports. The study also found that the exporting countries are currently under-performing with respect to their maximum potential to the global market indicating room for improvement

Comparing the community dependence on natural resources in Nyungwe National Park and the contribution of revenue sharing through integrated conservation and development projects

Rwanda Development Board (RDB) has recently established a tourism Revenue Sharing Scheme (RSS) to create a win-win approach in protected areas for effective biodiversity conservation and management. Through this scheme, around 1 billion Rwandan francs wereinvested to support around 152 Community Based Conservation Projects (CBCs), and integrated conservation and development projects (ICDPs). This paper assessed the contribution of CDCs projects around Nyungwe National Park (NNP) by evaluating their efficiency and effectiveness, and their socioeconomic impact to the local community development. Secondary data about the revenue sharing projects and the amount of money allocated to each project were collected from RDB office. Primary data were collected through the interview and focus group discussions. To verify the findings from RDB, interview and focus group discussion (FGD) were used. Interview was done with 500 households of local people around Nyungwe National Park and with community conservation wardens, while threats to NNP were verified by the consultation of reports from ranger based monitoring officers. The results showed that the value of resources collected by people from the park is higher than the revenue sharing support offered by RDB as (31.3 %) of respondents mentioned that exotic tree species were stolen and sold as poles where one pole was sold at around 6,800 Rwandan francs and 38.6 % of respondents proven that mining gave the much income. and consequently the revenue sharing scheme did not significantly reduce threats to biodiversity and its impact around NNP.A small percentage of people are happy because they were supported but a big number becomes unhappier and threaten the Park due to the gap in creating a win-win situation in biodiversity conservation. We recommend the revision of the whole revenue sharing scheme, taking into account the cost of livelihoods of community surrounding the park.Keywords: Efficiency, Effectiveness, Integrated Conservation, Development Projects, Revenue Sharing Schem

Heavy Metal Concentrations in Water Samples from Lake Kivu, Rwanda

Heavy metals are among the pollutants threatening the living organisms including human beings. The presence of heavy metals in water is of great concern due to their toxicity to aquatic organisms, humans and ability to accumulate in food chains. Thus, there is a need to regularly monitor heavy metal levels in aquatic medium. The present study was conducted to assess heavy metal concentrations in Lake Kivu water. Water samples from Lake Kivu were taken from three sites, namely: Rusizi, Karongi and Rubavu. Heavy metals in the samples were analyzed using Atomic Absorption spectro-photometer (SHIMADZU AAS-6800) and Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES).Copper, lead, cadmium, chromium, manganese, mercury and arsenic concentrations were determined. Copper ranged from 3.24 to 10.01 μg/l, lead varied from 8.81 to 37.44 μg/l, cadmium ranged from 5.01 to 14.01 μg/l,chromium was between 139.5 and 226.6 μg/l, manganese varied from 598.3 to 795.7 μg/l, mercury ranged from 0 to 0.047 μg/l, while arsenic was not detected in any of the analyzed water samples. Except for arsenic, all the other heavy metals exceeded the EPA (US Environment Protection Agency) maximum permissible limit for class III surface water intended for fish consumption and recreation. Thus, there is a need to establish the sources of lake water pollution by heavy metals in order to design further strategies limiting the amounts of heavy metals entering Lake Kivu. Keywords: Cadmium, chromium, copper, lead, manganese, mercur

A single channel speech enhancement technique exploiting human auditory masking properties

To enhance extreme corrupted speech signals, an Improved Psychoacoustically Motivated Spectral Weighting Rule (IPMSWR) is proposed, that controls the predefined residual noise level by a time-frequency dependent parameter. Unlike conventional Psychoacoustically Motivated Spectral Weighting Rules (PMSWR), the level of the residual noise is here varied throughout the enhanced speech based on the discrimination between the regions with speech presence and speech absence by means of segmental SNR within critical bands. Controlling in such a way the level of the residual noise in the noise only region avoids the unpleasant residual noise perceived at very low SNRs. To derive the gain coefficients, the computation of the masking curve and the estimation of the corrupting noise power are required. Since the clean speech is generally not available for a single channel speech enhancement technique, the rough clean speech components needed to compute the masking curve are here obtained using advanced spectral subtraction techniques. To estimate the corrupting noise, a new technique is employed, that relies on the noise power estimation using rapid adaptation and recursive smoothing principles. The performances of the proposed approach are objectively and subjectively compared to the conventional approaches to highlight the aforementioned improvement