Contribution to the knowledge of the ecological profile of some Melastomataceae of the Lesser Antilles: the case of Martinique ELY-MARIUS Séverine, JOSEPH Philippe, SOPHIE Stéphane, JEAN-FRANCOIS Yannis ABATI Yelji, CLAUDE Jean-Philippe, BAILLARD Kévine

Melastomataceae are particularly diverse in the Neotropical realm. The study of the sylvatic formations of the Lesser Antilles made it possible to identify the dominant floristic corteges associated with the different bioclimates. Although there are many indications that Melastomataceae are not among the species structuring the climax formations of the forests of Martinique, their ecological chorology and profile within these formations can be specified. The analysis of the biodemographic data of eco-units of different bioclimates, obtained during floristic inventories, confirms the indications of the floras of the region. It also makes it possible to provide some specifications concerning the ecological profiles of certain Melastomataceae. Conostegia calyptrata and Conostegia icosandra display a temperament of a heliophilous species of the sylvatic gaps. Clidemia umbrosa is a species affinis of smaller gaps or of trails. Miconia trichotoma is a more forestal species. Indexing terms/


INTRODUCTION
The Melastomataceae are the 7th largest family of Angiosperms and number 166 to 170 genera, including 4,200 to 5,105 species, according to the authors. They have a pantropical distribution but are particularly diversified in the Neotropical biome (107 genera, 2,950 to 3,000 species). [38,48]. Consideration of the phylogenetic data has led to a revision of the limits of the family in order to make it a monophyletic group. This sister group of the Myrtaceae would from now on include the Memecyclaceae. [7,47]. This research has also led to the repositioning of the limits of the differentiated tribes within the family.

Overview of the island
The Lesser Antilles, a small volcanic arc made up of about 21 main islands, along with numerous islets and sandbanks, consists of a total area of about 8,320 km2 [1]. The geomorphology of this insular arc is mainly conditioned by a subduction geodynamic. Its volcanic activity has allowed, in a submarine and then aerial environment, the successive implementation of sets of volcanoes of varying ages which constitute the majority of the reliefs of the island. Calcerous formations can be present on the surface. These are generally volcano-sedimentary formations and reef and para-reef formations. [14,47]. Martinique is an island of 1,128km2 whose highest point is Mount Pelée (1,397m). The reliefs are numerous but that contrasts with the southern part of the island where the majority of the reliefs are eroded and do not exceed 459 metres while all the recent massifs, which have a more substantial elevation, are gathered in the north. [14]. The volcanic origin of Martinique explains the contrasting geomorphology, along with 122 soil facies [3,44]. This diversity of soils, the orographic rains, the phenomena of bioclimatic inversions [21] as well as a substantial anthropogenic activity contribute to the creation of a mosaic of physical conditions. This complex pattern of abiotic factors thus determines, through the intermediary of bioclimates, the ecosystemic potentialities. [19,21,23]. Despite significant differences in surface area between the mountainous islands of the Lesser Antilles, four main types of bioclimates can be distinguished, determined mainly by the abundance of precipitation. [21,22].

Distribution of the main bioclimates and organisation of the large floristic complexes
Each sylvatic type is associated with a floristic potential that includes all the species that can be present according to the dynamic stage, the environmental conditions, their competitiveness within the phytocenosis and the history of the colonisation of the eco-unit looked at . [21].The different intra-successional stages are animated by an intra-stage dynamic. (See Figure 2). This plant dynamic is a pluri-directional phenomenon . [ 21,23] which contributes to the establishment and maintenance of a mosaic of phytocenosis. The evolution may be blocked by disturbances of anthropogenic origin but also sometimes by intrinsic conditions of the environment such as the instabilities of the ground or the topography. Natural disturbances such as windthrow or cyclones also contribute to the maintenance of this mosaic of phytocenosis. [17,18,21].

Method
The research presented in this article is based on an analysis of the data acquired from six inventories. (See Table 2 The taxonomic and biocoenotic interpretation of the samples of the different species of Melastomataceae described on the island was carried out based on an extensive bibliographic study as well as the use of floristic inventories. The floras selected for this study are the floras of HOWARD [16], FOURNET [9] and ROLLET [40,41]. Determinations were done with the flora of Fournet [13]. The taxonomic reference system: fauna, flora and fungi of metropolitan and overseas France (TAXREF V9.0), was used to account for possible synonymies [12]. For each station (Table 2)

Mature stage
Transition forest X X X X X X X Altitude formation X X X

Pioneer stage
Post-pioneer stage

Mature stage
No species of Melastomataceae is reported in the mature stages of the various types of sylvatic formation presented.

Floristic inventories
The determinations are conducted based on the flora of Fournet [9]. The taxonomy used therefore takes the names used in this flora with the exception of Conostegia calyptrata which will be distinguished from Conostegia montana [19] and not considered as a synonymy.

A. Dry bioclimate stations
Carrière 5 and Carrière 15 stations are located in a dry bioclimate.

a.Carrière 5
The floristic cortege of the station is presented in Appendix 1. Individuals less than 8m represent more than 81% of the individuals of the ligneous population. Three of the quadrats of this transect have less than 16% trees. 79% of the individuals over 1.3m recorded have diameters of less than 7.5cm. In the floristic cortege of this transect there are also Caesaria decandra, Aegiphila martinicensis, Zanthoxylum monophyllum. All the C. calyptrata individuals have diameters of class 2.5 and a height of less than 8m. They are in the two quadrats with the highest biomasses (quadrat 4: basal area: 0.4082, i.e. 25% of the total basal area, quadrat 5: basal area: 0.177115625 or 11% of the total basal area).

b. Vauclin Carrière 15
The floristic cortege of the station is presented in Appendix 2.  The population of quadrat 1 is made up of 91% individuals with diameters of class 2.5 and 5. This population has 87% individuals less than 8m.
The population of quadrat 2 consists of 96% individuals of class 2.5 to 5 and 95% of less than 8m. 81.3% of the ligneous individuals in quadrat 10 have diameter classes between 2.5 and 5. 66.1% of the individuals have heights between 1.3 and 8m. In this quadrat, the individuals with the most substantial biomasses belong to the species Mangifera indica and Cecropia schreberiana
The station's floristic cortege is presented in Appendix 3.

Figure 9: Distribution of height classes and basal areas -Aca_Ph.J Transect
The population of this transect is 18% trees of a height greater than 8m and 83% ligneous individuals culminating at less than 8m. 72.5% of the ligneous individuals of this transect have diameters belonging to classes 2.5 to 5. Dead and/or cut trees are found in all the quadrats. They represent 23% of the individuals belonging to the arborescent species recorded at the transect.
The species with the most significant indices of dominance are C. guianensis, P. racemosa and I. laurina. These dominant species are associated with a floristic cortege including Coccoloba swartzii, Eugenia pseudopsidium, Myrcia fallax, Bourreria succulenta, Eugenia monticola, Guarea glabra.
The Melastomataceae are represented in quadrats 1, 2, 3, 5, 6, 7, 8, 10 and 11 by a single species: Conostegia calyptrata.   At quadrats 3 and 4, there was also a significant decrease in the total basal area (4 and 5% of the total basal area). The population of these quadrats consists mainly of individuals of less than 8m (98 and 94%). Among the 3% of trees present across these quadrats, we find in particular species with the heliophilous temperament, such as Bursera simarouba, and hemisciaphilous species. In the population of individuals of less than 8m, hemisciaphilous species (Anthirhea coriacea, In quadrat 6, we can see that the basal area is nearly four times lower than that of the adjacent quadrats. Only 2% of the population of this quadrat consists of trees. In the cortege of this quadrat we find species with a markedly heliophilous temperament, Guettarda scabra, as well as species characteristic of secondary stages of the middle stage such as Pisonia fragrans and Faramea occidentalis. Melastomataceae are present in quadrats 1, 3, 4, 6 and 7.

C. Wet bioclimate stations a.La Richer1
The station's floristic cortege is presented in Appendix 5.

Figure 13: Distribution of height classes and basal areas per quadrat -La Richer1 Transect
The floristic survey carried out on this transect indicates that this population is 20% trees over 8m and 80% ligneous individuals with a height of between 1.3m and 8m.  Quadrat 1 has a low density of ligneous individuals. A dead tree has the most substantial basal area. The latter is the highest in the quadrat. M. trichotoma is represented by a young individual of diameter 2, 5, 5m in height with a first branching at 2m.
Quadrat 3 also has a low density of ligneous individuals of a height greater than 1.3m. It is marked by the presence of a dead tree of diameter class 30. There are also a significant number of regenerations of S. mahagoni and Heliconia caribea.
The population of quadrat 5 is made up of 19% individuals of a height greater than 8m. The presence of a dead tree of diameter 40 is also noted in this quadrat.
94% of the biomass of quadrat 7 consists of a mature individual of S. Mahagoni with a diameter of 110cm and a height of 40m. In this quadrat, Conostegia icosandra is represented only by young individuals of diameter class 2, 5cm in diameter and not exceeding 4.5m.
In quadrat 8, the most significant biomass is represented by a S.mahagoni of 25m and 40cm in diameter, under which young trees of dominant species of climax formations are developing.

b.La Richer2
The station's floristic cortege is presented in Appendix 6.    Their presence in combination with an anthropophyte species (Mangifera indica) which represents the largest biomass can be interpreted as the scar of a previous environmental degradation mainly associated with human activities. C. calyptrata is therefore associated with a perturbation in this station.
The dominant species are unique to the middle stage of formation and are associated with species of secondary stages of floristic potential of the lower plant stage [ 21]. This eco-unit can therefore be considered as a late secondary sylvatic formation with some intra-stational heterogeneity linked to perturbations. We note high tree mortality. Quadrats 3 and 9 are composed of heliophilous species (Bourreria succulenta, Myrcia fallax, Croton corilifolius, Bourreria succulenta and Pisonia fragrans) and hemi-heliophilous species or hemi-sciaphilous characteristic of sylvatic gaps (Ocotea coriaceae, Ocotea patens, Ocotea Cernua and Ixora ferrea) [21]. Quadrat 3 would be located in the centre of a large gap extending from quadrat 1 to quadrat 6. Quadrat 9 is also the most perturbed area with a gap which extends from quadrat 7 to quadrat 9.
Quadrat 13 also appears to have undergone an earlier or less significant perturbance because hemi-sciaphilous species such as Cassipourea guyanensis were inventoried. The sylvatic gaps observed appear to be mainly related to samplings and human activity. Conostegia calyptrata therefore appears to be a competitive species in perturbed areas.  The characteristics of the population indicate this would be a late secondary to pre-climax sylvatic formation within which there are gaps. The size and the organisation of the regenerations within these gaps are different.
In quadrants 8, 9 and 10 there are forest environment gap species (Guazuma ulmifolia, Chrysophyllum argenteum, Eugenia pseudopsidium) and secondary heliophilous species (Eugenia monticola, Croton corylifolius, Myrciaria floribunda) [21] . These associations would indicate that at the level of these quadrats, the transect crosses a gap of a significant size colonised only by young individuals. The organisation of the vegetation in this zone indicates that this is a gap recolonised by heliophilous species. Under the cover of these heliophilous species, secondary stages species of the middle stage are being established (Pisonia fragrans, Daphnopsis americana), but also the regenerations of final stage species of the middle stage the seeds of which are present in the adjacent quadrats.
Quadrats 3, 4 and 6 are located in an area with less substantial stratification than that of the two adjacent quadrats. This organisation may be indicative of less significant or older perturbations.
The distribution of the Melastomataceae across this station indicates that they are associated with areas which have undergone perturbations. Conostegia calyptrata is a competitive species in perturbed areas. Conostegia calyptrata would therefore also be competitive around the edges of sylvatic gaps.

C. Wet bioclimate stations a.Laricher1
The floristic cortege recorded indicates that this transect is located in a tropical submontane rainforest. It is a secondary (F.S.S) to late secondary (F.S.S.T) sylvatic formation. The conditions in which the individuals of the species Conostegia icosandra and Clidemia umbrosa are found suggest that they are species with a more sciaphilous character and which will therefore be found instead around the edges of intra-forest gaps.

b.Laricher2
The data from the survey would indicate that the transect is in a tropical submontane rainforest. We note the installation of climax species under the cover of the S. mahagoni. It may therefore be thought to be a late secondary formation. A gully is present at the transect. It constitutes a perturbation responsible for the low biomass present in quadrat 5.
These data suggest that while Miconia trichotoma appears to be present in areas where the forest cover is structured, Conostegia icosandra and Clidemia umbrosa appear to have a secondary heliophilous sylvatic gap temperament.

Conclusion
The first inventories and the field observations confirm the indications found in the floras. They also make it possible to posit some tendencies regarding the temperament of the Melastomataceae recorded. Representatives of this family are more abundant in wet and hyper-humid bioclimates. Some species such as Miconia mirabilis and Conostegia icosandra have been observed mainly at the edges and at forest roads. Conostegia calyptrata and Conostegia icosandra seem to present a temperament of heliophilous species of the sylvatic gaps. Clidemia umbrosa would also be competitive in the smaller-scale perturbations related to small windthrows or to the route of a path. Miconia trichotoma appears to have a more forestal character with an affinity for formations with poorly evolved stratification.
All the Melastomataceae of the studied stations have a low index of dominance as well as of distribution. These species show an aggregate distribution and a low competitiveness compared to the other species of the dominant floristic cortege. They thus represent a small proportion of the biomass of these eco-units.
Given the possible affinity of representatives of the family for perturbed environments, it seems essential to better characterise the organisation and the plant communities of sylvatic gaps but also of the edges of woodlands. The approach chosen in this study is based on an analysis of the biodemography of this population and using the known