The explanations. Forest is determined both by

The topic formulation, object of the present
study appealed to the frequent use of some concepts and terms that it required
to clarify for facilitating the understanding of this study. Concepts clarified
are: Forests, Forest Policy, Protected forests, Community forests, Ethnobotany,
Non-Timber Forest Products (NTFPs), Medicinal plants, tree bark for medicinal
purpose, Forest insects, xylophagous and their natural enemies.

Forests: According to FAO, 2015, forests are complex ecological system in which
tree are dominant or lands spanning more than 0.5 hectares with trees
higher than 5 meters and a canopy cover of more than 10 percent, or trees able
to reach these thresholds in situ. It excludes land that is
predominantly under agricultural or urban land use. This definition requires
some explanations. Forest is determined both by the presence of trees
and the absence of other predominant land uses. The trees should be able to
reach a minimum height of 5 meters. Forest includes areas with young trees that
have not yet reached but which are expected to reach a canopy cover of at least
10 percent and tree height of 5 meters or more. It also includes areas that are
temporarily unstocked due to clear-cutting as part of a forest management practice
or natural disasters, and which are expected to be regenerated within 5 years. Local
conditions may, in exceptional cases, justify that a longer time frame is used.
 It Includes forest roads, firebreaks and
other small open areas; forest in national parks, nature reserves and other
protected areas such as those of specific environmental, scientific,
historical, cultural or spiritual interest. Forests are also categorized
depending on the policy or the management mode.

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Forest
policy: A set of orientations and principles of
actions adopted by public authorities in harmony with national socio-economic
and environmental policies in a given country to guide future decisions in
relation to the management, use and conservation of forest and tree resources
for the benefit of society. We can distinguish Protected Forests,
Community Forests etc.  

Protected
Forests: Forest areas legally
protected for maintaining the high biodiversity values and comply the following
general principles; existence of legal basis, long term commitment, and
explicit designation as protected or protective forest area. Protected forests
are managed by foresters and all unlawful intrusions are forbidden.

Community
Forests: Community forests are managed by
communities or smallholders of forests and agroforests they own, as well as the
management of state-owned forests (some of which share customary tenure and
rights under traditional laws and practice) by communities (Molnar et al. 2011). Historically, all forests
were essentially owned by Indigenous Peoples, communities, and families. In majority
of developing countries, these rights were appropriated, however, in the face
of an expansion of feudalism, colonialism, and imperialism in the last five
centuries, until eventually almost all forests were claimed by the state. There
has been a slow move back to the recognition of local rights with popular
revolt and democratic practice. Worldwide, more than 430 million hectares of forests,
or 11 % of the total forest estate, are officially community owned or managed.
Local rights are more marked in developing countries, where, in 2008, 27 % of
all forest lands were community owned or administered. When tenure and rights
are recognized at the community and smallholder level, communities and
smallholders are empowered to create and grow a range of forest-based
livelihood and enterprise activities to improve their quality of life and raise
their incomes.

Habitat: The term
‘habitat’ is usually defined as a dominant vegetation formation, e.g. forest,
meadow or wetland (see e.g. Ricklefs & Miller, 1999). Furthermore it is an ecological or environmental area
that is inhabited by a particular species of animal, plant or other type of
organism. It is typically refers to the natural environment in which the
organism lives and where it can find food, shelter, protection and mates for
reproduction.

Habitat-type: a group of communities resembling
one another through habitat relationships (Shimwell, 1971).

Closed Habitat: In the present thesis, this term points
out all forest ecosystems without crops and agrosystems. 

Open Habitat: is part of a landscape that is not enclosed by tree and
may include plains, tundra, polar barrens, forest clear-cuts, agro-systems
(agricultural fields, young fallow etc.) and other areas free of tree cover
such as deserts. In open habitats the ground is more exposed to rain, wind and
light.

In the present study, we
adopted the term closed habitat for forest and open habitat for agricultural crop
in which some trees species have been saved.

Non Timber Forest Products: Non-Timber Forest Products (NTFPs) encompass biological materials used for purposes other than
for commercial timber and are essential for human life as they are
involved in daily needs of the population. NTFPs
produced in tropical forests can be grouped into four categories (Conelly,
1985; Peters, 1990;
Grundy and Campbell, 1993; Cunningham, 1996; Ayuk et al. 1999; Dovie et al. 2002, Ndangalasi et al.
2007): (i) fruits and seeds, with plant parts harvested mainly for fleshy fruit
bodies, nuts and oilseed; (ii) plant exudates such as latex, resin and floral
nectar; (iii) vegetative structures such as apical buds, bulbs, leaves, stems,
barks and roots, and (iv) small stems, poles and sticks harvested for housing,
fencing, fuel wood, and craft and furniture materials (e.g. carvings, stools).

In the present thesis, we
will focus on the third category that is vegetative structure such as bark
plant used in traditional medicine.

Ethnobotany
: The term Ethnobotany comes from the Greek word Ethnos, which means ‘people’,
and Botan? which means ‘herb’, so it would be generalized translate as ‘the
study of people and plants’. It was coined in 1895 by American taxonomic
botanist John W. Harshberger as the ‘the study of the utilitarian relationship
between human beings and vegetation in their environment, including medicinal
uses’ (Harshberger, 1896).

Medicinal plant species: The term of medicinal plants
include a various types of plants used in herbalism and some of these plants
have a medicinal activities. These medicinal plants consider as a rich
resources of ingredients which can be used in drug development and synthesis.
Besides that, these plants play a critical role in the development of human
cultures around the whole world. By definition, ‘traditional’ use of herbal
medicines implies substantial historical use, and this is certainly true for
many products that are available as ‘traditional herbal medicines’.

 Tree bark for medicinal purpose: Bark is one of the most important NTFPs in many countries worldwide and
it is periodically harvested from many tree species (Botha et al. 2004; Guedje et al. 2007; Pereira, 2007; Gaoue et al. 2008; Delvaux et al. 2009) for different purposes. From outside to inside of tree, the first part is the
bark and it refers to all the tissues outside the vascular cambium and is a
non-technical term (Raven et al. 1981). The bark consists mostly of two zones. The inner bark or phloem actively
contributes to the tree’s life processes: its tubular cells form the
“plumbing system” through which sugar and growth regulators,
dissolved in water, are distributed to other parts of the tree from the leaves
and buds where they are made. The outer bark consists of layers of inner bark
cells that have died and cracked as they have been pushed outward by the tree’s
growth.

Tree bark specially outer bark provides protection
against desiccation, fire, insects and diseases, and plays a key role in the
transportation of nutrients from leaves to roots through the phloem tissues,
thus bark harvesting may induce internal tree stress and increase vulnerability
to external agents (Gaoue and
Ticktin, 2010; Bugalho et al. 2011).

Wound in tree species or debarked
trees: An opening that is created when the tree’s protective bark covering is
penetrated, cut, or removed, injuring or destroying tissue. Pruning a live
branch create s a wound, even when the cut is properly made.

Xylophagous :
As explained by Beeson’s,
1941; forest insects are insects which live in a forest.Insects may  bore into
stems, bark, or even roots. They may also use trees as food supplies and habitats,
not only while the tree is alive but also after its death and, in the latter case,
play vital roles in decomposition and nutrient recycling (Xylophagous are all insects which directly consuming or feeding in or upon
plant tissue and hereafter referred to as ”wood-feeding species”. Depending
on tree host tissue, we can distinguish bark-feeding, phloem-boring and wood-boring
insects. Most bark-feeding and wood-boring insects can be categorized according
to the physiological state of their preferred hosts (Hanks 1999). While some
species are able to withstand the defence mechanisms of healthy trees, most
thrive on weakened, dying, or dead hosts. In the present study, we regrouped
all bark-feeding, phloem-boring and wood-boring insects into term xylophagous
insects. They concerned Species of families of Scolytidae, Buprestidae, Cerambycidae etc.

Natural
enemies: The xylophagous insects in their different
developmental stages are eaten or attacked by many species of animals. Two
groups of natural enemies are distinguished, those of predators such as
(Histeridae, Staphylinidae, Elateridae etc.) and those of parasitoids of which
the most important belonged to Ichneumonidae and Brachonidae of Hymenoptera
order and some  Diptera such as species
family of  Asilidae etc.