Description: Olea europea is an evergreen shrub or tree of 5-25 m. often with crooked stem and rounded crown.
Bark: Grey or dark brown bark which is rough and longitudinally fissured. Branchlets are white and dotted with breathing pores.
Leaves: Simple and narrowly oval leaves in opposite pairs. 2-8 cm long and 0.5-3 cm wide. They are glossy dark green above. golden or silvery beneath and leathery with prominent midribs.
Flowers: Small, white, or cream flowers, produced in branched heads. Fruits: Oval and fleshy drupes. 0.5-1 cm long, green when young, turning purple or black when ripe with a bitter-sweet taste.

Geographical distribution and ecological requirements: 0. europea is widespread from Ethiopia through East and Central Africa ta South Africa and Madagascar; also found in Arabian Peninsula, India and China. It grows in dry-upland forest (edges and remnants), often associated with Podocarpus and Juniperus species, from 850-31511 m. In Rwanda. this species is found in Bugesera. Umutara. Mayaga. Nyungwe and Akagera National Parks. at 1300-2400 m where rainfall varies between 214-1550 mm.

Uses: Timber, firewood, charcoal, poles, pasts, animal yoke, medicine (stem. bark and leaves), milk flavouring (smoking wood), bee forage, walking sticks, edible fruits (much liked by pigeons), shade, ornament, ceremonial and toothbrushes,

Propagation: 0. europea can be propagated by wildings and seedlings (difficult to raise).

Seed information: There are about 14000 seeds per kg with low germination rate reaching 20-80% in 20-45 days respectively. The species is a poor seeder. The collection should be done immediately after the fruit turns ta purplish black because of the competition by birds. Seed storage and pre-germination treatment: Pre-treatment is not required for fresh seed. Soak stared seeds in water for 48 hours. Seeds can be stared far 2 months at room temperature. Use fresh seeds for best germination results.

Management: 0. europea is a slow-growing species which needs pruning and thinning. Pollarding is also possible.

Remarks: The fruits of this species do not produce alive ail as subspecies europea which has been under cultivation in the Middle East for many years. Heavy woad produces much heat an burning and burns slowly. alive pales are very durable in the ground. This is one of the very important tree species with many uses. Therefore, farmers should be encouraged to grow this species in their farms.

Nduwayezu, J.B., C.K. Ruffo, V. Manini, E. Munyaneza, S. Nshutiyayesu. 20010. Checklist of Useful Trees and Shrubs for Agricultural and Pastoral Communities of Rwanda. Pallotti Press. Kigali, Rwanda. 264 p.

Introduction

Geographical setting of Rwanda

Rwanda is a land locked and densely populated country (408 persons per km2; annual growth rate of 3.5 %: 78 % rural farmers depending an less than 1 ha) (MINITERE. 2008) covering an area of 26.338 km2 and located between 1° 04' and 2° 51' longitudes South and between 28° 53' and 30° 5' latitudes East. It borders with Tanzania to the East, the Democratic Republic of Conga (DRC) to the West, Uganda to the North and Burundi to the South. The altitudes range between 1000 m in the southwest at Bugarama and 4500 m at Kalisimbi volcano in the northwest (Map 1). Rwanda shows a bimodal rainfall pattern with an annual rainfall ranging from 700 mm in lowlands to 2000 mm in highlands and the average temperature ranging between 16° C and 20° C. The vegetation and soil types of Rwanda are variable and closely linked.

Vegetation and sail types af Rwanda

Rwanda is characterized with 17 vegetation types of which the main six are the following:

(i) Montane rain forests in the western Province (Cyamudongo, Gishwati, Mukura and Nyungwe) found at 1500-3000 m:
(ii) Degraded submontane forest around Cyamudongo, Gishwati, Mukura and Nyungwe forests found in western Province at 1500-2000 m:
(iii) Grass savannas with Brachiaria platynota and different types of cropland in the central plateau found at 1600-2000 m:
(iv) Low altitude savannas with Themeda triandra and Hyparrhenia filipendula with zones of Loudetia simplex and xerophyllaus forest on the slopes and mesophyllous forest in the valleys found in the eastern and southern provinces (Akagera, Amayaga, Bugesera and Umutara) at an altitude of 1300-1600 m:
(v) Medium and high altitude swamps found at 1300-2500 m and:
(vi) Alpine and subalpine volcanic vegetation found at 3000-4500 m.

These vegetation types however, are very much influenced by various soil types (e.g. soil physical, chemical and biological properties) that are found in different parts of the country, implying therefore, that site-species matching is very crucial if rehabilitation of degraded lands in Rwanda is to be successful. The volcanic soils found in Volcano National Park. For example, bear very luxuriant vegetation because they are richer in sail nutrients than the alluvial soils of Akagera National Park which have poor vegetation types because of their law soil nutrients. moisture and aeration.

The soils of Rwanda originate mainly from physical-chemical degradation of schist, quartz, granite and volcanic rocks (MINAGRI. 2008). They can be divided into six major groups as follows:

(i) Soils derived from schist, quartz and sand stone found in Congo Nile crest, part of central plateau and northeastern highlands
(ii) Soils derived from granite and gneiss in the central plateau and eastern plains
(iii) Soils derived from basic intrusive rocks in the North
(iv) Alluvial and colluvial soils of marshlands and valleys which include mineral soils in the eastern valleys and organic soils of Akagera, Nyabarongo and Rugezi valleys.
(v) Soils derived from recent volcanic rocks found on foothills of volcanoes
(vi) Soils derived from ancient volcanic rocks found in the North-West of the Country

The long-term rainfall data for the past 96 years (1807-2003) clearly indicate that the observed vegetation types are closely linked with climate. It is apparent from Figures 1-29 that during the pre-and-colonial times the rainfall was higher as compared with that of the post-independence period. This high rainfall is probably attributable to low population density, long fallow periods and respect for forests (i.e. sources of food and medicine) while the observed rainfall reduction is mainly caused by intensified pressure an remaining natural forests and food production systems and the breakdown m the culture that the early subsistence models used to exploit and manage natural resources sustainably.

Man can improve or degrade the vegetation including forests, in the course of livelihood activities. When such activities result into forest destruction, life is threatened because forests play an important role in human's life.

Importance of forests
In Rwanda, forests provide many wood and non-wood forest products and other services of direct benefit to humankind. Rwandans use wood as a source of firewood, charcoal, timber, furniture, poles, pasts, flooring or paneling materials as well as beehives, tools and wood craft materials. The non-wood forest products am also important as they satisfy human basic needs including food (e.g. fruits, nuts, vegetables, jam, syrup, drinks, soup, seasoning and flavouring materials, gums,bees wax and honey), medicine, latex, dyes, fibres, resins, tannins, toxins, rapes, weaving materials, basketry, soaps, roofing material, mats, forage and fodder for feeding both livestock and wildlife.

Trees and shrubs are also a valuable resource because of their remarkable role in the improvement of our living environment and sail productivity, climatic amelioration, water source protection, carbon dioxide sequestration, conservation of biodiversity and tourism promotion.

Although forests provide human beings with numerous goods and services, available records clearly show that the Rwandan people have benefited from forest products and services in a rather limited way mainly due to the deforestation and land degradation problems which go hand in hand with forest cover disappearance, scarcity of forest products, lowered soil productivity and loss of biodiversity,

The report by MINAGRI (2002) shows that in the ISSO's forest cover of the country was 658,000 ha, The recent inventory of forest resources in Rwanda, however, revealed that forests and woodlands caver an estimated area of 240,746 ha (10 % of the total land) (Rutabingwa, 2008). This clearly shows that in the past 47 years (1860-2007). The country last 63,5 % of natural forests (i.e. representing an annual deforestation rate of about 8,800 ha) despite intensification of reforestation activities, Eucalyptus spp., Ptilus spp., Crevillea robusta and Acacia melanoxylon are among the main species composing the established forest plantations. Although Eucalyptus species (dominant species in Rwanda) has many uses and are easy to establish and manage, they have became a serious problem in many African countries due to their nature of mining soil nutrients, using excessive sail water and producing allelochemicals that suppress the growth of other vegetation. These negative effects of Eucalyptus species lead to the increased land degradation in many parts of Rwanda, The remaining natural forests that need urgent protection and conservation include Akagera, Nyungwe and Volcano National Parks, Busaga, Cyamudanga, Gishwati and Mukura forest reserves.

Land degradation, causes, consequences and remedial measures

Land degradation is a serious national and trans-national socio-economic complex problem which is mainly caused by deforestation, over-exploitation and poor management of our natural resources (i.e. land, water, forests, germplasm and wildlife).

Human settlement and agricultural expansion, commercial lagging, overgrazing, fuelwood and charcoal production and wild fires are among, the major causal factors of uncontrolled deforestation and land degradation in Rwanda. These causes are driven by rapid population growth, poverty and colonial, policies. The rapid family expansion and population growth and fast rate of urbanization changed the nature of forest utilization in Rwanda. To meet the demand for food and shelter peasant farmers converted more forests into human settlements and agricultural lands. Colonial policies Encouraging cultivation of export crops (e.g. tea and coffee) also accelerated conversion of natural forests to farmlands and increased demand for fuel for tea drying. These policies have also contributed to forest degradation by encouraging the establishment of monoculture Eucalyptus plantations in the most fertile medium and highland areas of Rwanda.

This extensive forest clearing, unsustainable farming practices and land degradation have serious economic, social and environmental consequences. The following are among the major economic, social and environmental consequences:

o Disappearance of forest cover
o Scarcity of forest products
o Decreased land and crop productivity
o Increased runoff, soil erosion. flooding and landslides with loss of lives and property and population displacement as a result of Gishwati forest clearing
o Increased sediment deposits and water pollution
o Lowered water levels as a result of poor land management impeded the Ntaruka hydroelectric installation from functioning
o Decreased women's farm labour and malnutrition as a result of firewood shortage ·
o Increased price of scarce wood products
o Loss of cultural heritage and knowledge
o Loss of biodiversity (i.e. tree diversity. habitat diversity and animal diversity)
o Climate change as a result of the build up of greenhouse gases into the atmosphere
o Watershed degradation resulting in disrupted hydrological regimes

To reverse the current situation. therefore. there is a need for rehabilitating the degraded lands through afforestation and reforestation schemes (e.g. single-and-mixed species plantations, catalysing native forest regeneration, regeneration through seeds, seedlings, coppices and root suckers), agroforestry practice, adoption of soil conservation measures. establishment of rotational woodlots, ensuring sustainable exploitation and management of natural resources. Reconciling wood supply and demand, control of population growth and alleviation of rural poverty.

Although there has been some government efforts directed at rehabilitating degraded lands, protecting and conserving the environment (e.g. establishment of REMA and NAFA, enforcement of forest laws and regulations, erosion control by terracing and tree planting, introduction of better land use systems: zero grazing system and lmidugudu), evidence exist to show that some of the remedial measures were not successful probably due to the high population growth rate. insufficiency of qualified human resources, rural poverty, unsustainable farming practices. poor crop-site matching, poor tree-site matching, inadequate knowledge about appropriate silvicultural management regimes and methods of domesticating valuable multipurpose trees and shrubs and loss of traditional knowledge of forest species and genetic resources that have economic applications. This book has been prepared with the purpose of identifying valuable multipurpose trees and shrubs that are suitable for rehabilitating degraded lands and drawing attention to the need for conserving biodiversity. It covers 222 indigenous and exotic species belonging to 68 families and 165 genera. It is worth noting however, that during the field survey two new tree species named Englerophytum natalense and Trilepsium madagascariense were recorded for the first time in Rwanda. The two species were all collected from Cyamudongo natural forest reserves.

Nduwayezu, J.B., C.K. Ruffo, V. Manini, E. Munyaneza, S. Nshutiyayesu. 20010. Checklist of Useful Trees and Shrubs for Agricultural and Pastoral Communities of Rwanda. Pallotti Press. Kigali, Rwanda. 264 p.

Use of the book

This book is recommended to village extension and rural development, students and university lecturers who will benefit from the knowledge. Consultants and experts in forestry and botany will find in this book useful information for their research, and for designing projects where the knowledge of tree species is required.

The Government of Rwanda should encourage dissemination of the findings from this study. It should be also provide an enabling environment and more resources to help resources to help researchers to carry out similar studies.

This book is divided into two main parts:
- Part I of the book is the main section which describes the species that are arranged alphabetically. In total the book covers 222 indigenous and exotic species belonging to 68 families and 165 genera:

- Part II is a list of vernacular and common names similarly arranged alphabetically.

To consult this book efficiently, the reader is advised to look at either vernacular or common name of the species which she/he wants from Part II of this book. Then she/he will consult Part I to obtain the information she/he wants. Alternatively, the reader may choose to use Part I directly if she/he already knows the botanical name of the species.

The following is the important information included for each species:

Plant names and origin

A current botanical name with at least one synonym and its country of origin have been given to each species according to the literature available including Flora of Rwanda (Flore du Rwanda). Flora of Tropical East Africa (F.T.E.A.) and Flora Zambesiaca (F.Z.). Local or vernacular names (if available) include Kinyarwanda: Rwa, Kirundi: Rundi, Luganda: Luga and Runyankore: Nkare, while common names include English: Eng. French: Fra and Kiswahili: Swa. These common names are those which are used by many people in East and Central Africa.

Description

Each species has been described briefly basing on both authors' field experience and available literature. The description of each species is based on main identification characteristics including growth habit, bark, leaves, flowers and fruits. Same photographs have also been included in order to facilitate species identification.

Geographical distribution anti ecological requirements

A brief description of the environment as it relates to the tree/shrub species and the location where the species is found in Rwanda, Africa and elsewhere in the world are given. Vegetation types, soil types, rainfall and altitudinal ranges have been given where the data are available. Rainfall data for all 30 districts of Rwanda, from the year 1907-2003 have been summarized in Appendix 1 (Figure 1-29). A distribution map showing different location where each species is found in Rwanda has also been given.

Uses
The uses of each species have been given in a summary form. These uses originate from different people in Rwanda authors' field experience and the available literature. Readers are therefore cautioned to seek more information from knowledgeable people before using them, especially if they are to be used for food or medicine as some of them have harmful effects.

Propagation and seed information
Different methods that famers can use in propagating each species have been mentioned. Moreover, same important seed information for the species which can be propagated by seedlings has been given. This seed information is about seed collection, extraction, pre-germination treatment, storage and germination rate.

Management and Remarks
Suitable management practices for each species included in this book have been proposed. They include coppicing, lapping, pollarding, pruning, weeding, trimming and thinning. In the coppicing system, trees or shrubs are allowed to regenerate from their stumps after being felled whereas in the lopping system. branches are cut from tree or shrub and used. Pollards are small branches that are produced after cutting the main stem of a tree or shrub at a certain height: say 2-4 m high.

Pruning is a method of reducing branches from shrub or tree in order to allow the plant to produce a dear and straight stem, while trimming is the removal of branchlets sideways as it is done far hedges and live fences. Weeding is the removal of undesirable plants in the plantation, and thinning is the removal of some individual plants from a plantation. These two last operations are aimed at reducing competition for light, soil nutri1mts and water. Some additional or very sensitive information has been given under remarks. These remarks are of special importance to the readers of this book.