Annex 8: Secondary forests: Towards a definition and typology for Africa
8.1 Presentation by Ms Unna Chokkalingam - CIFOR
In this presentation the results of the discussions of a task group on definitions and typology were presented. This task force was established during the workshop to elaborate a proposal on a secondary forest definition and typology that is appropriate for the specific conditions in Anglophone Africa. The results of the discussions were presented.
Suggested major vegetation types in Anglophone Africa.
There is a gradient of dense to scattered trees and
forest to non-forest vegetation determined by environmental conditions and
related fire regimes.
Can there be
- a forest definition or threshold based on the
percentage of canopy closure?
- Can trees be considered as woody vegetation > 5 m height?
The figure below is intended to help understand better the formation of secondary forest that can then lead to a better understanding of the typology for this resource. The reader can navigate from right to left of the figure and understand the gradient from a forest situation to a non-forest one.
Arguments for such a focus
- Non-forest vegetation is also important resources.
They can be degraded or kept degraded and require attention, but probably need
a different set of management strategies
- The limited potential forest areas could be managed for higher productivity
Usefulness of a secondary forest concept for Africa?
- Wet Africa - Primary and secondary forests are quite distinct and therefore they need different strategies for their management and uses.
- Drier Africa - Not much compositional change occurs even with intense disturbance; structural changes are more likely. Succession takes a longer time. The differences are not so obvious but exist, and succession could be managed (including seed production).
Original definition of secondary forest
The original definition states that these are forests regenerating largely through a natural process after significant human disturbance of the original forest vegetation has taken place at a single point in time or over an extended period, and displaying a major difference in forest structure and/or canopy species composition with respect to nearby primary forests on similar sites
Criteria for the definition of secondary forest in Africa
1. Nature of forest interference
Human and/or natural or both combined.
- rates of natural disturbance altered by humans
- importance of elephants and other game in the
formation of secondary forests.
- re-growth can be managed in a successional process even after a natural disturbance
2. Nature of re-growth
Largely natural, some planting is acceptable
- enrichment planting to complement natural regeneration
Major difference in structure and/or composition
- in drier areas, maybe mainly structural change
Do the following activities in Africa influence the definition of secondary forests?
- Swidden agriculture - does this system encourage
- Grazing - is it really that damaging to the forests
and does it encourage forest re-growth?
- Does the harvesting of NWFP, including bush meat
extraction, cause enough damage to the forest to consider it in the
- Logging - is the disturbance significant enough and
one of the main causes for the development and establishment of secondary
forests in Africa?
- What about the damage caused by fire?
- Rehabilitation/planting - is there enough natural regeneration?
- Following this definition, most forests in Africa can
be classified as secondary.
- Secondary forests may also be present in drier areas
(bush lands, shrub lands, open woodlands, and grass lands) where non-forest
- Non-forest vegetation is also an important resource.
It can be degraded and require attention as well, but a different set of
management strategies is required.
- The potential usefulness of secondary forests needs to be focused in order to understand and manage better this resource.
8.2 Discussion on proposed criteria and definition for Africa
- There was considerable dissent in response to the
proposal that only closed woodland and forests be considered for the status of
secondary forests. This was because large areas in arid to sub-humid Africa
are in open woodland, savanna and bushland, and these are viewed by people as
- There was a counter argument that the term or
distinction of SF needed to make ecological sense as well and that closed and
open woodlands needed different interventions or management options. The
country papers presented had distinguished between open and closed woodlands
and the density of trees was an easily identifiable parameter. A common
understanding of the term and types of vegetation to consider was required.
- There were responses implying that in any definition
of a forest, there is a need to move beyond pure ecological concepts and
consider human perceptions of a forest - it may be open woodland in Africa or
a closed canopy conifer forest in Europe. There is probably no single forest
definition that will apply to all continents. Any definition/delineation of a
forest versus non-forest would also have larger implications and potentially
affect ways in which areas are considered, classified, allocated or managed
- It was suggested that delineating between forests and
other vegetation was unimportant since they could just be seral stages as well
that needed to be seen as a whole. Several areas that are currently grasslands
and bushland could be potential secondary forest. The focus should be on the
secondary nature of the vegetation and the core issue in determining such
vegetation was the level of disturbance. The degree of disturbance to
determine whether it is secondary in whatever vegetation type it is should be
ascertained. There was a response indicating that the level of disturbance was
easier to see for closed forests than in open woodlands and could be quite
impractical in the latter.
- It was then proposed that what was meant by
significant disturbance be defined. There was a response suggesting that it
was also not feasible or useful to have a common threshold of significant
disturbance across regions, and was perhaps better developed at local or
- There was a call for inclusion of secondary forests
following natural disturbance as well. Natural disturbance through agents such
as elephants was very common in Africa and difficult and unnecessary to
distinguish from human disturbance. There was a response that natural
disturbance could not be altered or managed, but others suggested that the
subsequent successional process could be managed. A point was raised that
elephants cannot be blamed for disturbing forests and in fact they were the
agents of seed dispersal for some of the species. It needs to be recognized
that forest disturbances or interferences are not necessarily bad and
qualitative judgements are very relative.
- It was also observed that there had been discussions since Monday and a precise definition was not a constraint to these deliberations. No one had a major problem in identifying the main issues of secondary forests at the same time recognizing that the nature and extent of disturbances varied from country to country and forest type to forest type. A definition that is broad and general enough so that each country can modify it according to the forest types and conditions prevailing should be aimed at. In Latin America, concern for secondary forests emerged from the recognition that a valuable forest type was increasingly being converted into agriculture, plantations and other land uses. The issues that are being dealt with here are common issues for the forestry sector in general, loss and degradation of socio-economic, ecological and economic functions. Recognizing the existence of secondary forests could help focus some attention on preservation and use of such forests.
The proposed new definition of secondary forest for Africa based on discussions is:
"Forests regenerating largely through natural processes after significant human or natural disturbance of the original forest vegetation at a single point in time or over an extended period, and displaying a major difference in forest structure and/or canopy species composition with respect to nearby primary forests on similar sites".
Criteria for the definition:
1. What has caused the forest interference?
- Is it human or natural or both?
- Is the disturbance significant?
- Was the disturbance in a single event or cumulative?
2. Nature of re-growth
- Largely natural, some planting okay
- Major difference in structure and/or composition
- Trees/forest stage
The only difference between the definition used in Asia and this one is the inclusion natural disturbance, and in Africa this also means "animal". In addition, it was recognized that the thresholds for many components of the broad definition, such as significant disturbance, largely natural re-growth, major difference in structure and/or composition, and trees or forest stage need to be determined at country or regional levels.
Besides, the need for a restricted focus on just secondary forests versus looking at the whole gradient of secondary vegetation types which could be potential secondary forest was questioned, as well as the common presumption that forest disturbance or interference was always a negative force.