**2.2 Methodological approaches**

This work constitutes an analytical and conclusive synthesis of the research carried out, participative field investigations and works undertaken in production basins since 2013 (from 2013 to 2018) under the framework of the palm and forest project of Cameroon (PALMFORCAM-IRD) as well as Oil palm Adaptative Landscape (OPAL). The main missions included:


The quadrate method is advantageous because it helps in studying the dynamics of the fauna and flora in a quantitative and qualitative approaches. As flora recording is concerned for the analysis of the impact of oil palm farming on


**Table 2.**

*Methods used in assessing the impact of oil palm plantation in the environment.*

plant biodiversity, experimental plots were applied on four types of vegetation's namely: a village or smallholders oil palm plantations, an elitist oil palm plantations, an industrial palm plantation and a forest area. To this effect, the team realised an experimental plot where recorded plant species were immediately identified.

Criteria such as the nature, probability of occurrence, scope or extent, magnitude or intensity, reversibility and duration of the identified impacts were combined for an appropriate impact assessment. The rating grid of Leduc and Raymond [19] was used for impact assessment. Ratings from 1 to 5 were assigned to the indicators (**Table 3**) depending on the degree of impact. The absolute importance represents the average of the impact ratings over the total number of rated indicators. The nature of an impact can be positive (+) ▲ or negative (−) ▼ on the environment concerned.

The absolute importance or significance of the impacts is determined by calculation by taking the product of all the ratings assigned to each indicator over the total number of indicators. This is illustrated by the following equation:


**Table 3.**

*Impact assessment indicators and rating of their impacts.*

(intensity x reversibility x extent x duration xoccurence) Absolute importance <sup>5</sup> <sup>∑</sup> *Ratings* <sup>=</sup> (1)

After rating the impacts were qualified according to the results obtained.


The critical impact threshold is established when the rating value is greater than or equal to the average of the grid: 3.

To complete methodology and tools used, it is worth mentioning that oil palm is one of the most studied agricultural speculations in Cameroon today. Its cultivation and oil production are of interest to economists, sociologists and anthropologists because of its income-generating character and the by-products are used in traditional pharmacopoeia. With further investigations carried out in the Sanaga-Maritime oil production basin (2018–2020), under the coordination of WWF and EPFL Switzerland, three work packages have been developed since 2018 till 2020 on the intercropping of oil palm:


This study also take into account various meetings held with the actors of the Africa Palm Oil Initiative (APOI), whose objective is to seek and support the transition to a sustainable palm oil not linked to deforestation in Central and West Africa.
