Spatial Analysis of the Woody Flora of the Djoumouna Peri-urban Forest, Brazzaville (Congo)

The spatial analysis of the flora of the peri-urban forest of Djoumouna has been conducted in Brazzaville, Congo. Data collection, conducted from April to August 2017, is based on a floristic inventory of 75 plots of each 400 m2 (20 m x 20 m). The study shows 898 trees of dbh ≥ 10 cm corresponding to 106 species and 36 families. The number of individuals per plot averages 11.97 ± 0.42 feet/plot while the number of species per plot averages 7.37 ± 0.30. The land used by projecting the trunk sections is on average 0.74 ± 0.05 m2/plot. The Jaccard similarity coefficient between plots is between 0 and 75% while the average Skewness is 1.26 ± 0.11. The average Shannon index is 1.77 ± 0.05 per plot with an average maximum diversity of 1.93 ± 0.04. The average Pielou index is 0.91 ± 0.01. The absolute diversity index averages 6.54 ± 0.29 while α-Fisher averages 11.44 ± 1.39. The average value of the Green index is -0.04 ± 0.01 and finally 7.55% of taxa have a rarefaction index of species between 40 and 77% compared to 92.45% where this index varies from 81 to 99%. The upward hierarchical classification and the AFC highlight the presence of floristic subfacies resulting from taxa independence. Since most species have a density of less than 1 tree.ha-1, the floristic composition is heterogeneous, resulting in insufficient natural regeneration and low resilience of this ecosystem threatened with extinction in the very short term