First Community in Abandoned Pasture Lands or Crops in Eastern Cuba’s Rainforest over Metamorfics Rocks

: Miconio prasinae – Cyatheion arboreae alliance is described. Although it has five associations, we address three in this work, corresponding to immediate, secondary and early successional communities in abandoned pasture lands or crops in submountains rainforest over metamorphic rocks. The objective of this work is to study the first communities in used and abandoned fields, because they are of a great importance in the understanding of the vegetation’s evolution and for management purposes. In the submontane forest on the metamorphic complex, the destruction of mature vegetation produces important losses in climatic biodiversity and transcendental changes in ecosystem composition. The change in soil use, especially the transformation to pastureland, has favored the development of herbaceous and shrubby plant communities. This study is not only of practical relevance in describing the associations of the pine forests the plant associations and the study of the ecological conditions in which they develop, but its results can be used as a working tool in the environmental management and silviculture for the restoration of degraded areas. The study of diverse Cuban vegetation types suggests that the methodology of Zurich Montpellier’s school is more effective as compared to other authors because its syntaxa is good to recognize and is able to transform in a forest typology. The main species are pioneers heliophilous with a type of "r" selection.


Introduction
Although there are some works about succession in Cuban forest [8,15,16]; there was not enough those made on mountain areas [18].
In submountain rainforest over metamorphic complex [18] destruction of maturity vegetation produce important loses in climacic biodiversity and transcendental changes in ecosystemic composition. In a similar ecosystem Caluff [4] and Sanchez-Ruiz [22,23] had quantify heavy losses of pteridological and spiders diversity with the change of use of soils, getting the maximum with pasturelands transformation.
The objective of this work is to study the evolution of first communities in used and abandoned fields in the submountain rainforest ecotopes over metamorphic complex in rainiest areas of Cuban archipelago.

Methodology
Natural conditions of the studied area. The area is inside the more rainy territory of Cuban archipelago, between 2 500 to 3 000 mm [13] regularity distributed. Geology is represented by Sierra del Purial Formation [7], composed by different kind of schist, intermediate tuffs between other rocks. Relief is very dissected with slopes between 35 and 45° rarely less. Soil is ferralitic red and leached red-brown colour [14], frequently little deep, over ferralitic weathering crust.
Sampling methodology According to Braun Blanquet [3] methodology phytocoenological inventories (lists, stands, samples, relevés), with a minimum area of 625 m 2 [18] were made. In addition, observations of the ecotope (slope; exposition; altitude; general, nano and micro relief) were made in the place of the samples and their surroundings.
For the characteristic combination of the associations, the species with degrees of presence IV and V [24] were used, and for the subassociations and variants the differential combinations.
Herbaceous and secondary scrub, constituted by the immediate and early secondary communities that develop in abandoned fields and slopes that are produced in the construction of the roads in areas of the submountain and mountain rainforests (sometimes known as cloud forests in the Antilles), it is generally rich in ferns.
This phytocoenose represent an early community formed for the abandonment of a pasture land and a crop field respectively in northern expositions. Nowadays constitute a Homeostasis I and beginning of Fiera II also, in which mainly Cyathea arborea constitute a dominant layer between 7 and 10 m high.
It is developed over a yellow and leached ferralitic soil, loamed and with gravels, in which is observed a dense rootlets (rhizoids) of the tree fern before mentioned in the first 4 or 5 cm of the profile, at 10 cm deep this rhizoids are not found. The humus layers are absent, principally fronds of dominant fern are observed; is considered that moreover of a fast decomposition, because of the big slope the formed humus will be drag for the intensity of rainfalls.
In the inventory 2 is observed that trees break the Cyathea arborea layer and interact between them, beginning the stage knowing as Fiera II. The species here present are: Ficus membranacea, Cupania glabra, C. americana, Cecropia peltata, Cordia sulcata, Guarea guidonia, Casearia sylvestris subsp. sylvestris, Zanthoxylum martinicense and Spondias mombin.
The shrub layer is very variable in its cover the more prominent specie is Miconia prasina and in the second inventor also Calyptronoma occidentalis, and the rest have less cover. The herbaceous layer is the more floral diverse, the majority of species are scarcely (Table 3). In the 15.02.2004 (N20°17', W74°43.4') was study.

Discussion
In the syntaxa evolution of submountain rainforest over metamorphic rocks [19], when a secondary stage (field or pasture land) is cut, burn and late abandoned it will conform a immediate secondary community like Neurolaeno lobatae -Lantanetum camarae association.
Result very interesting to observe how during these first stages of the serie the majority of species are of herbaceous type, frequently with ferns dominance. However with the succession advanced process (immediat, early and late communities) obviously the structural complexity grow (Table 3).
Its consolidate the concept that in this first stages of the serie almost the totality of species are heliophilous mainly with a type of "r" selection [9,19] and only exceptionally arboreal elements of mature rainforest are found [18].
It is confirmed that in the studied area, due the great levels of precipitations and its relatively uniformity, in the Homeostasis I a differentiation of associations is produced as a function of exposure. The elements of the north exposure develop a dominant community of Cyathea arborea, while those that evolutioned in south exposure Miconia prasina is the predominant. This is also a coincidence with the importance of this exposition for the cultivation of arum (Xanthosoma sagittifolium Schott.); R. Ruiz (com. pers.) said that arum cultivate in north exposure putrefy, while in south exposure has a normal develop.
It is to important to emphasize how in the developed communities with tree ferns predominance its rhizoids conform a dense layer that protect the soil against the erosion, which is a coincidence that soft roots predominate in this first stages [5,6]. This communities are very similar to the humid forest of México where Cyatheaceae are very distinguished elements [17].
It is outstanding that in the Fiera II beginning for be located in the surrounded of a mature forest the seeds rain function have a great efficiency to arboreal species enter. Is also considered that in this stages the majority of biomass found as stems and leaves, frequently is not woody [12].

Conclusions
When a secondary succession developed, in the first stages, communities are represented mainly by herbaceous pioneers heliophilous with a type "r" selection that are also generalist species. We also observed that in the Homeostasis I, with a small arboreal layer, the exposition defines the dominant species in the canopy in these places with leached ferralitic soil originating from metamorphic rocks with 2,500 to 3,000 mm annual rainfall. It is also considered that canopy species entry is produced in the surroundings of the forest as a result of seeds rain.