Biodiversity Indicators

Biodiversity indicators for the Cameroon Mountains

Levels of biodiversity

The Convention on Biological Diversity considers biodiversity and ecological processes at three different levels: ecosystem, (communities of) species and genotype level [CBD]. According to the International Association for Impact Assessment (IAIA), possible impacts of a proposed activity at each level of diversity can be best assessed in terms of composition, structure and function [IAIA, 2005]. In a similar approach, the former Kilim Ijim Forest Project [Kilim-Ijim Forest Project, 1998] that was aimed at protecting the montane forest on the Kilim Ijim ridge in the Cameroon Mountains, conservation goals were monitored against three groups of indicators: a) montane habitat, b) key species important for ecological processes and c) populations of rare species.

Community forestry combines both conservation efforts and human activities aimed at exploiting the forest and therefore the biodiversity indicators to monitor community forestry should give information about both aspects. In line with the approach followed by the CBD [CBD] and the KIFP [Kilim-Ijim Forest Project, 1998] biodiversity indicators for community forestry in the Cameroon Mountains are recognised at three levels:

Montane ecosystem
Species important for ecological processes

Rare or important species.

At each level different biodiversity indicators are identified that together give a good description of the biodiversity at that level. Biodiversity indicators in the Cameroon Mountains were selected in a participatory approach with local NGOs, people working and living in the forests, representatives from the relevant ministries in Cameroon, and consultants. Suggestions from (inter) national experts in the field of biodiversity or community forestry were included; see Annex 4 for an overview.

Indicators were selected according to the following criteria:

All 3 levels of biodiversity are covered
Unique (endemic) elements of biodiversity are included
Human activities in the forest are included
Indicators can easily be identified and monitored by local people

Each indicator is described below in some detail, for more detailed information please check the references.

Level 1: Forest level

At ecosystem level indicators are selected that give information on the ecosystem as a whole, in this case the montane forest ecosystem. There are 4 different aspects of the forest ecosystem that are monitored, each with one or more biodiversity indicators.

1.1. Growth and Stability of montane forest

The first and possibly most important part of community forestry is to make sure that the forest stays intact and does not become smaller. The following indicators are used:

1.1.1. Boundary respected. If the forest boundary is respected and no encroachment of surrounding farms occurs, this is a good indicator that the forest stays intact.
1.1.2. Closed canopy. In a healthy montane forest, the forest canopy is closed. Only the occasional tree that has fallen due to natural causes may result in an individual opening in the canopy. If there are many openings in the canopy this is a clear sign of recent felling of trees.
1.1.3. Undergrowth intact. In a healthy and mature montane forest, there is a dense undergrowth of plants and bushes. If there are openings on the forest floor this is an indication of human activity, e.g. harvesting of medicinal plants, clearing for rattraps, farming, wood collection.
1.1.4. Number of farms, hectares affected. Farming requires clearing of the undergrowth or felling of trees and is usually not allowed in a community forest. The number of farms and the number of hectares affected is noted.
1.1.5. Number of fires, hectares affected. Natural fires may occur occasionally but a more real risk is incoming fire from burning grassland around the forest by graziers or hunters or even by deliberate arson. All signs of fire should be noted and the most likely source the fire should be noted.

1.2. Water systems

The forest cannot survive without water, but water will also quickly dry up in the dry season if the forest is decreasing. Therefore the amount of water in the forest throughout the year is a good indicator of the health of the forest: the more water, the better.

1.2.1. Number permanent streams. The number of streams that carry water throughout the year, also in the dry season, is reported. This number should stay constant or increase.
1.2.2. Number seasonal streams. The number of streams that carry water in the rainy season but fall dry in the dry season is reported. This number should stay constant or decrease in favour of permanent streams.
1.2.3. Depth of stream. The depth of a stream is a good indicator for the amount of water transported by a stream. This is measured at the same spot in the river with a solid bottom, e.g. on a rock under water. The amount of water may vary through the year, but over the years there should be no decrease.
1.2.4. Size of lake. If there is a lake in the forest, the level of the water should be noted. This is measured at the same spot on the shoreline. The amount of water may vary through the year, but over the years there should be no decrease in the water level.

1.3. Decrease exotic animals and plants

Exotic animals and plants do not belong to the forest and may be harmful to the original animals and plants.

1.3.1. Cattle. Cows, goats, and pigs destroy the forest, no cattle is a good sign. The number of animals and the likely owner are noted.
1.3.2. Domesticated cats and dogs. These animals hunt for the animals in the forest like birds and rats, their number is noted and should be low or zero.
1.3.3. Eucalyptus and Cypress trees. These tree species use a lot of water and dry out the forest. Low numbers of exotic trees is an indicator of a healthy forest.

1.4. Effects on people.

The people need the forest for many purposes and these livelihood activities should not be harmed. The indicators show the status of the livelihood activities in the forest.

1.4.1. Prunus. Prunus bark is sold to the pharmaceutical industry and is a big income-generating tree in the forest. The number of Prunus trees should remain constant or increase. The trees should be healthy and only harvested sustainably according to the procedures laid down in the Simple Management Plan.
1.4.2. Forest rats. Rats are hunted by the people and their numbers should remain constant or increase.
1.4.3. Timber. Timber, defined as trees that have died and fallen by natural causes, is used for furniture. The amount of timber should remain constant or increase.
1.4.4. Medicinal plants. Medicinal plants (e.g. Pittosporum veridiflorum, Agauria salicifolia) are harvested by the people for personal use or for sale. The amount of medicinal plants should remain constant or increase.
1.4.5. Spices. Spices (e.g. Piper umbellatum, Piper capense) are harvested by the people for personal use or for sale. The amount of spices should remain constant or increase.
1.4.6. Cola nuts. Cola nuts are harvested by the people for personal use or for sale. The amount of cola nut trees should remain constant or increase.
1.4.7. Amount of dead wood on forest floor. Dead wood is harvested by the people for personal use as fuel or for sale. The amount of dead wood on the forest floor should remain constant or increase.

Level 2: Process level.

At process level indicators are selected that give information on the functioning of the forest ecosystem and essential ecological processes that keep the forest alive. There are 3 different processes that are monitored.

2.1. Important Natural processes

Important natural processes are essential for the forest to function and keep the forest alive. These processes are usually difficult to monitor directly but some indicators can give a good idea about the overall functioning of the forest.

2.1.1. Number of fruiting trees. Fruiting trees are important food sources for birds and animals like e.g. Bannermann's turaco and monkey's and as such are a good indicator of the functioning of the food web. The amount of fruiting trees should remain constant or increase.
2.1.2. Amount of honey produced. Bees are important in pollination, and the amount of honey produced in the forest can therefore be taken as an indicator of pollination. The honey is collected from beehives. The amount of honey produced should remain constant or increase.
2.1.3. Number of bush dog (civet), wild cat (cerval) and birds of prey. Predation is an important process in the forest to take out the old and sick animals. Sightings of numbers of predators are a good indicator for this process. Numbers of predators should remain constant or increase.
2.1.4. Litter thickness. The litter thickness reflects the amount of leaves and dead organic matter produced in the forest. If the forest canopy is closed and the forest floor is wet, both signs of a healthy forest, the litter layer will be thick and harbour lots of animal and plant life. If the forest is not productive, has been burned or is exposed to sunlight, the litter layer will decrease.
2.1.5. Plants growing on branches/trunks of trees. Epiphytes (plants growing on trees like e.g. orchids, ferns) are characteristic for a healthy montane forest, and usually contain many rare and endemic species. Epiphytes mainly grow on mature endemic trees with a closed canopy and are therefore a good indicator for a healthy montane forest.

2.2. No Isolation of animal/plant groups

If the forest becomes fragmented, animal and plant species may become isolated and the population may become endangered.

2.2.1. Length & width gap in forest. Gaps in the forest dividing the forest, e.g. through farming or fire are noted, no gaps in the forest is an indicator of a healthy forest.

2.3. Changes in forest plants & wildlife

The forest may stay intact, but still changes may occur in the structure of the forest, types of plants, trees and animals that live in the forest etcetera. This is a natural process, but some changes are influenced by human activity and can be taken as indicators of change due to the community forestry activities.

2.3.1. Gnidia glauca. This tree is usually seen in a regenerating forest, e.g. several years after a fire or after farming activities. The tree grows up to 15 meter tall and is used locally for papermaking. This tree is an indicator of a positive change in the forest.
2.3.2. Trema orientalis. This small tree is usually seen in degraded forest where human activity is recent or ongoing, e.g. after a fire or on recently abandoned farms. This tree is an indicator of a negative change.
2.3.3. Bracken fern. Bracken fern grows on open spaces in the forest, especially after a fire. Bracken fern is an indicator of a negative change.

Level 3: Species level

The third level of biodiversity is the level that is most easily recognised, as it comprises individual species of plants and animals. At the species level both species that are indicative of a healthy montane forest, as are unique endemic species that live only in the Cameroon Mountains and nowhere else on earth, are included. The Cameroon Mountains are extremely rich in endemic species and are an internationally recognised hot spot for biodiversity. However, many endemic species cannot be easily recognised and therefore they only form part of the indicators. It is important to select for each individual forest a set of indicator species that is actually present in that forest, as not all species are present in all parts of the Cameroon Mountains. This is especially true for the endemic species, which may be found only in limited areas.

3.1. Birds.

The Cameroon Mountains are the third richest area for endemic birds in Africa. Birds are hunted for food and numbers of (large) birds and endemic birds are a good indicator of a healthy montane forest. Depending on the area, different endemic birds should be monitored, as they are not present throughout the Cameroon Mountains.

3.1.1. Bannerman's Turaco. This is a large and beautifully green-red coloured bird with a characteristic red crest that plays an important role in the local tradition and is easily recognised by the local people. The bird is endemic to the Bamenda Highlands and can therefore only be monitored in this area. The numbers of Bannerman's Turaco should remain constant or increase.
3.1.2. Mount Cameroon Francolin. This is a large mainly brown ground dwelling bird (bush-fowl) with a characteristic song that can easily be recognised by local people. It lives only on Mount Cameroon. The numbers of Mount Cameroon Francolin should remain constant or increase.
3.1.3. Great Blue Turaco. The Great Blue Turaco is a very large and beautifully blue coloured bird with a characteristic blackish crest that is found throughout the Cameroon Mountains in healthy (lowland and montane) forests and is often hunted. The numbers of Great Blue Turaco should remain constant or increase.
3.1.4. Other endemics. Depending on the location and identification skills of the local people, other endemic birds can be included as biodiversity indicators. The numbers of endemic birds should remain constant or increase.

3.2. Large Animals.

Large animals like mammals are hunted to extinction in most montane forests. The presence of these animals is already scarce and sighting of them is a good indicator of both a healthy forest and low hunting pressure.

3.2.1. Monkeys. Local people know the species of monkey well and they include endemic species like the Preuss's guenon. Any sighting is a positive sign, the numbers should remain stable or increase.
3.2.2. Apes (nests, feaces). Great apes like gorilla and chimpanzee still exist in the Cameroon Mountains. Most populations have now been identified and are monitored in separate programs. Still any sighting outside these recognised populations, however unlikely, is a good sign, the numbers should remain stable or increase.
3.2.3. Duiker. Duikers are small deer that are hunted for food and are a good sign of a healthy forest and low hunting pressure, the numbers should remain stable or increase.
3.2.4. Squirrel. Squirrels are important in seed dispersal and contain an endemic species, Coopers Mountain Squirrel. High numbers of squirrels are a good sign, the numbers should remain stable or increase.

3.3. Plants & Trees.

Plants and trees form the basis of the montane forest and contain high numbers of endemic species. Many of these plants and trees are used by the local population as traditional medicine or for woodcarving and can be easily identified by them.

3.3.1. Indian bamboo. Indian bamboo grows in patches in the forest and forms a small ecosystem in its own right. The size and distribution of these patches should roughly stay the same.
3.3.2. Dovyalis sp. Shrub, endemic to the Bamenda Highlands. Dovyalis sp is collected for medicinal use and rats eat the fruits. The numbers should remain stable or increase.
3.3.3. Chassalia liakomensis. Bush coffee. Chassalia liakomensis is a shrub endemic to Cameroon Mountains. The numbers should remain stable or increase.
3.3.4. Oncoba sp. Oncoba sp is a shrub endemic to the Bamenda Highlands. The fruits of the plant are used locally to make musical instruments. The numbers should remain stable or increase.
3.3.5. Dombeya ledermannii. This tree is endemic to the Cameroon Mountains and used locally for boundary fencing. The tree has white flowers and is easily recognised. The numbers should remain stable or increase.
3.3.6. Polyscias sp. This tree is characteristic for a mature forest and is locally used for carving xylophones. The numbers should remain stable or increase.
3.3.7. Cordia sp. This tree is characteristic for a mature forest and is locally for woodcarving. The numbers should remain stable or increase.