Plotless sampling techniques, linear recordings of distances among random trees or points and trees were developed to overcome some limitations of plot-based or quadrat methods by reducing time consuming, sampling effort, etc. However, research works proved that some points need to be clarified in order to provide a more useful guidelines for ecologists. The main objective of this study is to make a critical review of literature on plotless sampling techniques in vegetation studies. For this purpose, most original studies published and focused on plotless techniques in plant communities were identified via Keywords searching on scientific database websites and additional references from retrieved articles. Thereafter, about hundred papers were sampled in this review through careful reading of the abstract, methods and results. This study revealed that plotless sampling methods are mainly used to estimate population density. Furthermore, this study showed that among the plotless sampling methods that were described, some remains slightly documented in ecology to date. Results obtained also showed that the spatial distribution of organisms impacted the performance of these methods. All plotless sampling methods recorded their best performance when the population is randomly distributed. When the population is uniformly or contagiously (clump) distributed, most of them produced the largest bias of density estimate. However, over all spatial patterns, distance measurements at least to the third nearest neighbour were the best preferred methods. Therefore, further research works need to control this bias, to continue some investigations on those methods mainly on measurement errors and detection process.

The study assessed the floristic diversity and analysed the structure of plant groups in the Pénéssoulou Forest Reserve (PFR). For this purpose, 234 plots of 50 m × 20 m each were installed in delimited floristically homogenous stands. An individualization of the different plant groups of the PFR was carried out using non-metric multidimensional scaling. Alpha diversity indices were used to evaluate the floristic diversity of the plant communities. Dendrometric parameters and size class structures of diameter and height were performed to understand the conservation status of the identified plant communities. Four plant communities was identified: G1 corresponded to woodlands and savannah woodlands with Vitellaria paradoxa and Uapaca togoensis as characteristic species, and including 81 woody species; G2 corresponded to forest gallery, dominated by Anogeissus leiocarpa and Cola gigantea and including 100 woody species; G3 corresponding to tree and shrub savannahs with Vitellaria paradoxa and Parinari curatellifolia as characteristic species, and including 64 woody species; and G4 corresponded to Anogeissus leiocarpa - Lonchocarpus sericeus dry forest that included 75 woody species. The dendrometric parameters varied significantly from a plant group to another (P-value < 0.05). The distribution of tree diameters was in an inverted «J» shape, characteristic of multi-species stands. As for the structures in height, they reflected a rarity of higher individuals (>20 m). The results showed an acceptable state of conservation and a good natural regeneration capacity of the forest, which must be improved through the implementation of a forest management plan.