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Know Some Useful Trees and Shrubs for Agricultural and Pastoral Communities of Rwanda

Authors:
Nduwayezu Jean Baptiste
Nduwayezu Jean Baptiste
Nduwayezu Jean Baptiste
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Christopher K. Ruffo
Christopher K. Ruffo
V. Minani
V. Minani
V. Minani
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Munyaneza Em at Rwanda Cultural Heritage Academy
Munyaneza Em
  • Rwanda Cultural Heritage Academy
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Abstract

222 described indigenous and exotic tree and shrub species, with information about species' geographic distribution, ecological requirements, uses, seed storage, seed pre-germination treatment, propagation and management regimes.
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Know Some Useful Trees and Shrubs for Agricultural and Pastoral
Communities of Rwanda
J.B. Nduwayezu
C.K. Ruffo
V. Minani
E. Munyaneza
S. Nshutiyayesu
Institute of Scientific and Technological Research (I.R.S.T.), Rwanda
2009
Published by Pallotti Press
Gikondo - Kigali
Rwanda
© 2009 Institute of Scientific and Technological Research (IRST)
P.O. Box 227, Butare, Rwanda
Cataloguing this book:
J.B. Nduwayezu, C.K. Ruffo, V. Minani, E. Munyaneza and S. Nshutiyayesu
Know Some Useful Trees and Shrubs for Agricultural and Pastoral Communities of Rwanda 2009. Institute of
Scientific and Technological Research (IRST), P.O. Box 227, Butare, Rwanda, 264 p. ISBN 978 99912-0-869-5
First published in 2009
Front cover photos:
Top: Montane forest of Nyungwe National Park, buffer zone tree plantation and tea estate at Gisakura
Top left: Terraced land in Musanze district
Top right: Mountain Gorilla (
Gorilla gorilla berringei
)
Centre: Map of Rwanda bearing its national flag colours
Bottom left: Fruiting
Sterculia tragacantha
at Bugarama hot spring
Bottom centre: Rwandan woman carrying a bunch of banana from her farm and a baby on her back
Bottom right: Cows (Inyambo) grazing in Nyagatare village
ISBN 978 99912-0-869-5
The views expressed in this book are those of the authors and do not necessarily reflect the views of IRST.
Neither the authors nor the publisher can be held responsible for any consequences arising from
misidentification, consumption or any other form of use of the plants described in this book.
Copyright:
Copyright in publication © Institute of Scientific and Technological Research (IRST) 2009
Copyright in the text © The authors 2009
Copyright in photographs © The authors 2009
Copyright in species distribution maps © The authors 2009
Copyright in rainfall graphics and cover design © Dr Nduwayezu, J.B. 2009
All rights reserved: No part of this publication may be reproduced, stored in any retrieval system or transmitted
in any form or by any means, without prior permission in writing of the copyright owners.
... Newtonia buchananii is a tall deciduous tree 10-40 m high, with a rather flat crown which grows in lowland and upland rain forest, usually near streams, ground water, or as a component of riverine, mist or swamp forest at range of 600 -2100 m.a.s. l (WAC 2002) found in tropical Africa from East to Central and Southern Africa (Nduwayezu et al. 2009) In Uluguru mountains, the species is found in both south and North Uluguru, and it dominates the canopy below 1800 m.a.s.l (Frontier-Tanzania 2005) Newtonia buchananii protects riverine soil from erosion, the tree's crown gives light shade, the leaves are used in agriculture as mulch, N. buchananii crown gives light shade, which may not injuriously affect other crops in agroforestry systems and produce Fodder: The foliage and pods are eaten by livestock and can be gathered as fodder, N. buchananii is a good source of nectar and pollen for bees, a good source of quality firewood, and the brown to red-brown hardwood is durable in water and thus a favourite for boat/ canoe building. Poles from the tree are used in house construction (Orwa 2009). ...
... Due to its importance, this timber species is becoming rare in its natural habitat due to overexploitation (Nduwayezu et al. 2009). In Uluguru Nature Reserve (UNR) researches conducted found the exploitation of the species (Frontier-Tanzania 2005), which raises the concern of the species protection status in the reserve. ...
... In Kalinzu Nature Reserve, Uganda the absence of large-sized individuals of L. swynnertonii and N. buchananii in the three forest areas was a result of intensive logging because of their high value timber (Muhanguzi et al. 2007). Same threats face the species in Rwanda (Nduwayezu et al. 2009). In Mozambique, Newtonia buchananii was found to be dominating the tropical moist forests which also clearing of the forest increased as people were left without alternatives for living and the banana planting appeared promising (Müller et al. 2005). ...
Newtonia buchananii abundance and distribution in relation to altitude and human disturbance: A study in uluguru nature reserve, Tanzania
Article
Full-text available
  • Sep 2015
Newtonia buchananii in Uluguru Nature Reserve was reported to be depleting as a result of its extraction. This research was designed to find out the trend of abundance of Newtonia buchananii, its distribution in terms of diameter classes, altitudinal gradient and human activities that either directly or indirectly have impact on the mentioned species in Uluguru Nature Reserve, Morogoro, Tanzania.Four transects were laid across the gradient and 10m×50m plots were designed for data collection which were diameter at breast height (dbh) for trees taller than 1.3m. Seedlings were counted in small plots of 2m×2m. All disturbances within the plots were recorded. It was found that, Newtonia buchananii is abundant at the altitude below 1800m.a.s.l and it is not found higher than 1900m.a.s.l, the abundance decreased with altitude on the undisturbed plots. The other observation was high mortality of N. buchananii seedlings, high occurrence of human activities near the forest edges and electricity line which has resulted to clearing of the forest. Protection of the forest edges is important for the protection of N. buchananii. Forest encroachment has to be discouraged at the lower altitudes. Entrance into UNR has to also be further supervised to avoid uncontrolled establishing of many footpaths.
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... In an attempt to analyze trends in the dynamics of ornamental plant diversity since the arrival of European colonizers, checklists were compiled using data extracted from available literature and field survey. Four clusters were recognized: [1] the 1900 checklist: includes plants that were commonly used as neighborhood trees in Rwanda at the arrival of European colonizers, as extracted from several history publications such as D' Hertefelt et al. (1962), Van Noten (1983, Bindseil (1992), Muzungu (2003), Murasandonyi (2009) as compiled by Egli and Kalinganire (1988), Glatz et al. (1992), Fischer and Hinkel (1992), Bartels (1994), Burren (1995); [3] the 2009 checklist: includes those listed by Bloesch et al. (2009) andNduwayezu et al. (2009), and [4] the 2011 checklist: includes those identified by this study, but also Seburanga (2011). ...
... A total of 631 plant species, 350 woody taxa and 124 trees were recorded, a figure far greater than those published in previous and parallel works (202 woody species listed by Nduwayezu et al. (2009); 78 herb, tree and shrubby species reported by Ndayisenga (2011) in Huye city, Southern Province). With regard to the composition of native plant assemblages (37% and 25% Tropical African and Rwandan native species, respectively), our findings are to some extent comparable to those of Celesti-Grapow et al. (2006) who reported a proportion of native species amounting to 61% and 32% of the total number of species, respectively in residential neighborhoods and newly developed sites of Rome city; but apparently different to those of Lososová et al. (2012) who found that native taxa accounted for 47.62% of total number of species in central European cities, and Seburanga (2011) who reported a 50-percent share of native ornamentals in South China's cities. ...
Amenity trees and green space structure in urban settlements of Kigali, Rwanda
Article
  • Jan 2013
According to the national policy, overall forest and agroforestry cover in Rwanda is to increase up to 30% land cover by 2020. On the other hand, demographic data reveal that Rwanda's urban areas are among the fastest-growing on the continent. Unfortunately, there is only little information of the effects of such a rapid urbanization on tree cover and green space structure, knowing that data on urban plant assemblages in the country are rather rare. The paper discusses developments in Kigali's green spaces with regard to its rapid rate of expansion. An integrated approach of research, combining results from interview sessions, desk-based investigations, walk-over and vegetation surveys, and photogrammetric analyses of remotely acquired imagery was applied. The findings suggest that the city green space network consists of plant assemblages largely dominated by alien species (75%). Tree cover fraction averaged at around 10–35%. No significant difference was observed between field-drawn and photogrammetric-based fraction of tree cover estimates; making the later a quick but cheap tool for rapid tree cover evaluation. Cultivated forests, urban woodlots and domestic garden tree stands are far the most dominant types of green spaces in terms of coverage of city surface area. Street tree communities and institutional gardens appear to be the most intensively designed green space layouts. Both distribution and species composition in domestic gardens were socioeconomic-driven. For instance, palm trees were characteristic of fortunate quarters while fruitbearing ornamental such as Psidium guajava and Persea americana were common within scattered and informal settlements. Markhamia lutea, Erythina abyssinica, Euphorbia candelabrum, Phoenix reclinata and Acacia sieberiana are among native taxa that thrive to keep a place in the city. Euphorbia tirucalli, a native tree that is widespread in home compound fences within informal settlements, is significantly declining as modern housing expands and concrete-based fences replace live enclosures.
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... The increase in food requirements for the growing population has increased the pressures on land and water resources, which degraded the lands, reduced biodiversity and affected most of the water resources in Rwanda [7,8]. This serious national and transnational socio-economic complex problem was caused by deforestation, over-exploitation and poor management of the natural resources [9]. ! ...
The Effects of Trees on Soil Chemistry
Article
Full-text available
  • Mar 2019
Background: Trees often affect the chemical properties of soil, positively or negatively. Objective This paper studied the effects of Podocarpus falcatus and Markhamia lutea trees on soil chemistry in Ruhande Arboretum, Rwanda. Methods Soil samples were collected using Zigzag method from Arboretum forest of Ruhande at different depths (0-20, 20-40 and 40-60 cm). For each plot, 25 samples were collected to make one composite sample per plot for each depth. Results The results showed that tree species contributed to the changes of soil chemistry along the depths of the soil layers. The laboratory analyses showed that there was a high significant influence of tree species on soil pH and Aluminum ions. However, it was observed that there was no significant influence of Podocarpus falcatus and Markhamia lutea species on the available phosphorus or on the total exchangeable acidity. On the other hand, analyzing soil samples under Markhamia lutea showed an increase in the total nitrogen and a decrease in the pH and available phosphorus. Conclusion Trees affect the chemical properties of soils. Therefore, it is recommended that under acidic soils, for example, forestry and agroforestry actors should use less acidifying tree species, such as Markhamia lutea and Podocarpus falcatus.
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... In Kitabi area, HCl, NO 2 , TVOC and O 3 were reduced by 76.6% (from 0.214 to 0.05 ppm), 54.6% (from 0.119 to 0.054 ppm), 74.8% (from 1539.9 to 387.9 μg/m 3 ) and 72.7% (from 0.033 to 0.009 ppm) while NO 3 , SO 2 and CO were reduced by 100% as compared with Kigali City respectively. These lowered levels of air pollutants in Kitabi area can probably be caused by high efficiency of photosynthetic process attributable to high and varied vegetation cover which is in conformity with other findings suggesting that trees and shrubs play an important role in the improvement of our living environment, climatic amelioration and carbon sequestration [19]. ...
Quantification of Air Pollution in Kigali City and Its Environmental and Socio-Economic Impact in Rwanda
Article
Full-text available
  • May 2015
This 9-months study was conducted in Kigali City and Nyamagabe District during the 2012-2013 period with the overall aim of raising awareness about the benefits of cleaner energies (biodiesel) and human health risks and negative environmental and socioeconomic impact of fossil fuels (petrol and petro diesel) that are commonly used in Rwanda. MAHA MGT 5 Emission Tester and MAHA MDO 2 LON Emission Tester/Opacimeter were used to measure gas emissions (CO 2 , CO, Unburned Hydrocarbons and Opacity) from gasoline or petrol and diesel vehicles respectively. Air composition (HCl, NO 2 , NO 3 , SO 2 , H 2 S, TVOC, O 3 , CO, CO 2) in the study sites was measured using Gray Wolf-Advanced Sense HVAC Environmental Test Meter while water quality was analyzed at the Water Laboratory of the National University of Rwanda. Annually, a total of 526,327.1 tons of carbon dioxide (CO 2), 18,405.5 tons of carbon monoxide (CO) and 354,967.0 m 3 of unburned hydrocarbons (HC) are released into the atmosphere of Kigali City by both petrol and diesel vehicles. Using 100% Biodiesel reduced emission of CO by 50% and Opacity by 76.9% while using a Biodiesel-blend or Biodiesel-Diesel mixture (B 50) reduced CO and Opacity by 35.2% and 71% respectively. In the Kitabi area surrounded by Nyungwe Forest Reserve air contaminants HCl, NO 2 , TVOC and O 3 were reduced by 76.6%, 54.6%, 74.8% and 72.7% while NO 3 , SO 2 and CO were reduced by 100% as compared with Kigali City respectively. Water contaminants were also higher in Kigali City than forested areas of Nyamagabe. It is concluded that continuous use of expensive fossil fuels may result in increased human health deterioration, environmental degradation, lowered human work productivity and slow economic growth in Rwanda. Using cleaner energies (i.e. biodiesel), however, results in improved human health, living environment and socioeconomic development. Planting suitable tree species, frequent monitoring of imported fuel quality and establishment of new fuel quality regulations and guidelines, national ambient air quality standards and national air quality emission standards are very crucial if we are to assure our future generations of a quality life and living environment. However, more studies on pollution by all types of motor-vehicles, industries and other machinery are needed in Rwanda. Detailed studies on mathematical modeling of air pollutants in major cities of Rwanda are also urgently required to evaluate air pollution dispersion and assist in forecasting the air quality.
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... Natural forests and woodlands play a vital role in the existence and survival of most of the living organisms in Botswana and other parts of the world. They are storehouses for a diversity of plants and animals, provide water, food, fodder, forage, fuel wood, mulch, building materials and medicines and fulfill both cultural and spiritual needs [1][2][3]. They also enhance ecotourism, absorb carbon dioxide (CO 2 ) and supply the much-required oxygen (O 2 ) for breathing [4, 1]. ...
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Comparative Study of Germination and Initial Growth in Nursery of Three Agroforestry Species at Ruhande Arboretum in Rwanda
Article
Full-text available
  • Jan 2018
Agroforestry extension in Rwanda has economic, environmental benefits and its role in improving soil fertility among other numerous benefits. This research undertook a comparative germination and initial growth study of the three agroforestry species namely Senna spectabilis, Leucaenna trichandra, and Calliandra calothyrsus at Ruhande Alboretum when seeds are sown directly in pots and indirectly in seedbed. The germination period spanned from one to three weeks for three species. Senna spectabilis germinate at 8.0% in seedbed sowing method and 3.7% in pots. Germination rate of 49.7% was recorded for Leucaena trichandra in seedbed while 66.7% was recorded in pots. For Calliandra calothyrus a germination rate of 45.3% was recorded in seedbed while 50.3% was recorded in pots. For Senna spectabilis direct sowing in pots produced seedlings which are taller (16.1cn) and bigger (2.72 cm) than their counterparts in seedbed. Seedlings in pots showed a big variability (6.5) in height among themselves and a big deviation from the true mean (16.1± 5.408) compared to seedlings in seedbed both in mean height and coral diameter. For Leucaena trichandra direct sowing in pots produced seedlings which are taller (26.25) and bigger (3.28 cm) than their counterparts in seedbed. Seedlings in pots showed a low variability (4.857) in height among themselves and a low deviation from the true mean (26.25±1.34) compared to seedlings in seedbed which showed a bit high variability (4.929) and a big shift from the true mean (25.43±1.36) both in terms of mean height and coral diameter. The difference both in mean height and coral diameter was not significant at 5% level of probability for both Senna spectabilis and Leucaena trichandra. For Calliandra calothyrus direct sowing in pots produced seedlings which are taller (26.55cm) and bigger (3.02cm) than their counterparts in seedbed. Seedlings in pots showed a big variability (3.6) among themselves and a big deviation from the true mean (26.55±0.999) compared to seedlings in seedbed .Although there is no significance between means in terms of height, the difference in mean coral diameter is significant at 5% level of probability. Since direct seeding produce taller seedlings than seedbed method, it should be preferred when one has little time to prepare for plantation and not high quantity of seedlings is needed.
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Comparative Levels of Water and Air Pollutants in Kigali City and Kitabi and Benefits of Cleaner Energy-Biodiesel in Rwanda
Article
Full-text available
  • May 2015
To compare both levels of water and air pollutants in Kigali city and Kitabi and benefits/disadvantages of the fuel types (gasoline, diesel and biodiesel) that are used in Rwanda, a parallel study on water and air pollution was conducted in Kigali city and Kitabi-Nyamagabe District during the January-July 2013 period. All vehicles entering Kigali City via Giticyinyoni, Nyacyonga, Gahanga and Rugende axes and the total number of motor vehicles in Rwanda were recorded. Carbon dioxide (CO 2), carbon monoxide (CO), unburned hydrocarbons (HC) and opacity are the main emissions parameters measured at the Rwanda National Police Motor-vehicle Inspection Centre. The air quality parameters measured include HCl, NO 2 , NO 3 , SO 2 , H 2 S, TVOC, O 3 , CO and CO 2 while quality of rain water harvested from the study sites was determined by measuring pH, conductivity, total dissolved solids, turbidity, biochemical oxygen demand, organic matter, sulfates, aluminum, copper, iron, manganese, cadmium, chromium, lead, sodium, and oils and grease. Kigali capital city suffers tremendous pressure of increasing population accompanied with the rapid increase in the number of vehicles which emit 526327.1 tons of CO 2 year-1 , 18405.5 tons of CO year-1 and 354967.0 m 3 of unburned hydrocarbons year-1. Using 100% biodiesel reduced emission of CO by 50% and opacity by 76.9%, while using a 50% biodiesel blend or biodiesel-diesel mixture (B 50) reduced CO by 35.2% and opacity which is strongly correlated with properties of particulate air pollutants by 71%. In Kitabi area, HCl, N0 2 , TVOC, 0 3 , CO 2 , NO 3 , SO 2 and CO were reduced by 76.6%, 54.6%, 74.8%, 72.7%, 100%, 100% and 100% as compared with Kigali city respectively. Levels of acidic air pollutants (SO 2 and NO 2) are negatively correlated with rain water acidity (pH) levels (SO 2 : r = 0.787; NO 2 : r = 0.734) implying, therefore, that atmospheric deposition of strong acids or acidic pollutants lowers the water pH levels or increase water acidity. Reductions in atmospheric deposition of strong acids and other toxic pollutants may result in some improvements in the acid-base status of some water bodies which can lead to increased growth conditions for various organisms. The use of cleaner energies (i.e. biodiesel) therefore, may be a practical option of controlling emissions or managing air pollution causes. More detailed studies, however, are needed to determine the contribution (quantitative and qualitative) of each source of pollutants to both air and water pollution in Rwanda and identify other key emission control measures to be undertaken. Also efficiency of photosynthetic process of trees that are commonly planted in Kigali city needs urgent investigation.
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Self-Established Black Wattle Populations in Rwanda: Implications for Nature Conservation
Article
  • Nov 2015
Based on empirical evidence from a vegetation survey, this paper investigates the occurrence of self-established populations of black wattle (Acacia mearnsii De Wild.) in various environmental contexts and identifies areas where this species could be allowed to grow as a useful plant. The frequency of occurrence of self-established black wattle was found to be comparatively high above 1600 m of altitude. Three agro-ecological zones of Rwanda (Congo Nile Crest, Non-volcanic Highlands and Central Plateau) account for 70 % of the occurrence, most of which are inside tree plantations and woodlots and natural forests. In areas of most concern to black wattle invasion (especially in proximity of natural ecosystems), the following policy approach should be considered: eradication of current occurrences and a ban on the cultivation of this species. Elsewhere, control through utilization by local communities and adaptive management in areas least vulnerable to its invasion could suffice to keep this species under check.
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Photosynthetic capacity of tropical montane tree species in relation to leaf nutrients, successional strategy and growth temperature
Article
Full-text available
  • Feb 2015
  • OECOLOGIA
Photosynthetic capacity of tree leaves is typically positively related to nutrient content and little affected by changes in growth temperature. These relationships are, however, often poorly supported for tropical trees, for which interspecific differences may be more strongly controlled by within-leaf nutrient allocation than by absolute leaf nutrient content, and little is known regarding photosynthetic acclimation to temperature. To explore the influence of leaf nutrient status, successional strategy and growth temperature on the photosynthetic capacity of tropical trees, we collected data on photosynthetic, chemical and morphological leaf traits of ten tree species in Rwanda. Seven species were studied in a forest plantation at mid-altitude (~1,700 m), whereas six species were studied in a cooler montane rainforest at higher altitude (~2,500 m). Three species were common to both sites, and, in the montane rainforest, three pioneer species and three climax species were investigated. Across species, interspecific variation in photosynthetic capacity was not related to leaf nutrient content. Instead, this variation was related to differences in within-leaf nitrogen allocation, with a tradeoff between investments into compounds related to photosynthetic capacity (higher in pioneer species) versus light-harvesting compounds (higher in climax species). Photosynthetic capacity was significantly lower at the warmer site at 1,700 m altitude. We conclude that (1) within-leaf nutrient allocation is more important than leaf nutrient content per se in controlling interspecific variation in photosynthetic capacity among tree species in tropical Rwanda, and that (2) tropical montane rainforest species exhibit decreased photosynthetic capacity when grown in a warmer environment.
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Black Wattle (Acacia mearnsii De Wild.) in Rwanda’s Forestry: Implications for Nature Conservation
Article
  • Feb 2015
Invasive species pose a serious threat to the conservation of biodiversity. Forestry is the most important driver of the introduction and spread of invasive woody plant species after horticulture. Nearly 450 invasive tree species have been recorded worldwide, amounting to more than half the world’s total invasive woody flora. Australian-native Acacia mearnsii De Wild is one of world’s top invasive alien tree species related to forestry. The negative impacts of alien species spilling over into conservation areas because of forestry are increasingly being recognized, and we examined the context and timing of this Australian species’ arrival in Rwanda. The role of A. mearnsii in Rwanda’s colonial and postcolonial forestry and the species’ threat to biodiversity conservation are also investigated. The results suggest that A. mearnsii [I] was introduced into Rwanda between 1903 and 1918, with the earliest formal record dating back to 1941, [II] was a major forestry tree species until the late 1960s when its use in forestry declined significantly, and [III] demonstrates a comparatively higher occurrence and potential of regeneration within the understory of Eucalyptus plantations within the Congo−Nile Ridge buttress, Bufundu and Bushiru, and Budaha, Ndiza and Buberuka agro−bioclimatic zones. More recently, A. mearnsii has invaded national parks and forest reserves above 1600 m of altitude. The most significant case was recorded at Nyungwe National Park, East Africa’s largest montane rainforest. A study of biomass and spatial patterns of this species in specific ecosystems, such as Nyungwe National Park, is strongly recommended in order to uphold effective conservation practices.
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