**3.2 Physiognomic characteristics**

Dry forests of Lac-salé and Ngouni-Hamboda (**Figure 3**) presente 3 strata, with some emergents with *Adansonia digitata* and Albizia sp. at a height of up to 20 m:

• A continuous lower stratum, with a recovery rate of 50% and an average height between 1 and 3 m. This stratum consisted in numerous grasses and shrubs such as *Acalypha indica* (Euphorbiaceae), *Oeceoclades lonchophylla* (Orchidaceae) (specie that is becoming increasingly rare in the north of the island), *Aloe alexandrei* and seedlings or young plants of the upper strata species *Erythroxylum platyclada, E. lanceum (Erythroxylaceae), Diospyros comorensis* (Ebenaceae)*,* Ochna ciliata (Ochnaceae) and *Turraea wakefieldii* (Meliaceae).

**Figure 3.** *Dry forest of Hamboda with a mesophilic tendency.*

*Phytoecological Study, Ethnobotanical and Dynamic of Dry Vegetation in the Ngazidja Island… DOI: http://dx.doi.org/10.5772/intechopen.107330*


In the Ifoundihé-Chambouani dry forest, three strata were identified with some emergents with *A. lebbeck* and *A. glaberima* and at a height of up to 15 m:


**Figure 4.** *Drypetes comorensis (fruits).*

**Figure 5.** *Turraea virens (flowers).*

• An upper stratum of 6 to 12 m, discontinuous mainly composed of *Operculicarya gummifera* (Anacardiaceae), *F. sycomorus* (Moraceae) and *A. lebbeck* (Fabaceae). The minimum area value was 300 m2 . It corresponded to a number of 60 species.

Dry thickets of Singani (**Figure 6**) and Domoni-Ambouani-Hahaya have no stratification, with a very open canopy (10–20% recovery rate). It is a shrub vegetation 5 to 8 m high, which differed from other formations in the region only by reducing the size of the species and their foliage. Only baobabs and Albizia exceed 8 m and can reach 12 m. The minimum area of this thicket is 250m2 and corresponds to 48 plant species. The dominant species are *Pyrostria bibracteata, Euclea racemosa subsp. schimperi, A. digitata, Vitex doniana, Albizia glaberrima, Phyllarthron comorense, F. sycomorus, Erythroxylum platycladum* (Erythroxylaceae), *Oeceoclades lonchophylla* and *Acampe pachyglossa* (Orchidaceae). The soil is covered by numerous seedlings of *Phyllarthron comorense, Euclea racemosa subsp. schimperi*.

**Figure 6.** *Acampe pachyglossa on tree of Vitex doniana, in dry Singani ticket.*

*Phytoecological Study, Ethnobotanical and Dynamic of Dry Vegetation in the Ngazidja Island… DOI: http://dx.doi.org/10.5772/intechopen.107330*
