Clear differences are encountered between dominant species in the Homeostasis I in the north and south expositions of the territory located on the most rainfull zone of Cuban archipelago, in first Cyathea arborea is observed while Miconia prasina as the second. In the evolution of vegetation after the disturbance, the Homeostasis I succesional stage it`s the first where heliophilous species (sun-loving) closet a cover layer that create stable coverage and better conditions to emerge rainforest species (shade-loving), and begin to disappear pioneer heliophilous species with a type of “r” selection. For the work Braun Blanquet methodology was employed and the objective is to analyze the phytocoenological composition in the Homeostasis I areas.

Keywords: secondary succession, rainforest, homeostasis I, metamorphic rocks, Eastern Cuba

Submountain rainforest over metamorphic rocks¹ is developed over schist of Sierra del Purial geological formation which is an easily weathered material, and for that it is a relatively favorable soil conditions and as these terrains form part of the most rainfall zone of the Cuban archipelago, it have the adequate conditions to vegetal develop. Actually is found inside of Cuchillas del Toa Biosphere reserve.²

Much of this rainforest areas have been altered by using the "clean - tomb - itch - burn - inhabits" method to prepare for subsistence agriculture; nevertheless, there are many forest possessions, some of them relatively vast and much different successional stage areas; for that the objective of the present is study the phytocoenological composition in the Homeostasis I areas.

Natural conditions of the studied area

Natural conditions were described in the first work of this group.³ The area is located inside the more rainy territory of Cuban archipelago, between 2 500 to 3 000 mm⁴ regularity distributed. Geology is represented by Sierra del Purial Formation⁵ composed by different kind of schist, intermediate tuffs between other rocks. Relief is much dissected with slopes between 35 and 45° rarely less. Soil is ferralitic red and leached red-brown color,⁶ frequently little deep, over ferralitic weathering crust.

Sampling methodology

The sampling methodology is found in the former work of this group (3); although the last were exposed summarily.

According to Braun Blanquet⁷ methodology phytocoenological inventories (lists, stands, samples, relevés) in a minimum area of 625 m² were made.¹ In addition, observations of the oecotope (slope; exposition; altitude; general, nano and micro relief) in the place of the samples itʹs surroundings were made too.

For the characteristic combination of the associations, the species with degrees of presence IV and V were used,⁸ and for the subassociations and variants the differential combinations.⁹ was followed for the categorization and the name of syntaxa. Completed scientific names (genus, species and author) are observed in Tables and^10–14 sometime amended by

The following phytosociological arrangement was made:

• Class Clidemio - Cyatheetea arboreae Reyes 2021.
• Order Clidemio - Cyatheetalia arboreae Reyes 2021.
• Alliance Miconio prasinae – Cyatheion arboreae Reyes 2021.

This alliance have five associations, in this work two of them were described:

• Miconietum prasinae,
• Clidemio-Cyatheetum arboreae.

Miconietum prasinae Reyes & Acosta ass. nov.

(Table 1, holotypus inv. 3.)

Figure 1 Association Miconietum prasinae in south exposition.

Miconietum prasinae association with 29,1 species average is present in abandoned fields with exposition south, soils are red ferralitics and leached, coming from Sierra del Purial formation schist. Microrelief is regular and slope is between 12 to 45 degrees, with 20 to 22 degrees dominance; studied altitude was between 480 and 580 mosl.

Mainly layer was the shrub, between 4 and 5 m high and a cover of 80 to 100 %; the said layer is composed almost totally of Miconia prasina (Sw.) DC., frecuently isolated individual of Cupania americana L. and sometimes Psydium guajava L. were encounter. According to Viento Frio`s inhabitants, this stage is reach about the 12 years to be abandoned the field. The same corresponding for the layer close with a Homeostasis I.

In this stage a humus layer developed still not observed, more frequent results L layer sometimes dispersed, the rest are traces, only where Fiera II begin is more developed (Inv. 7) layers L and F are defined; with frequency rainfalls had washed the surface.

Some stages with the beginning of Fiera II were found, with an incipient canopy layer of 7 to 12 m high and 10 to 30 % cover; where furthermore of Cupania americana, Bactris cubensis Burret, Buchenavia tetraphylla (Aubl.) R.A. Howard, Calyptronoma occidentalis (Sw.) H.E. Moore, Sapium laurifolium (A. Rich.) Griseb., Clusia rosea Jacq., Spondias mombin L., Alchornea latifolia Sw. and more dispersed Chrysophyllum oliviforme L. subsp. oliviforme, Cecropia peltata L. and Schefflera morototoni (Aubl.) Maguire were locally observed.

Two variants were differentiated Byrsonima coriacea and Cupania americana.  It was studied 17-19.02.2004 (central part of territory N20⁰17ʹ, W74⁰43,4ʹ).

In addition to Table 1. Inv. 1. Securidaca virgata L. r, Ipomoea microdactyla Griseb. r, Panicum sp. +, Philodendron lacerum (Jacq.) Schott r; Inv. 2. Polygala leptocaulis T. & G. 1, Sauwagesia brownei Planch. 2, Pitirogramma calomelanus (L.) Link +, Zanthoxylum martinicence (Lam.) DC. r, Tabebuia sp. r, Neurolaena lobata (L.) R. Br. r, Solanum nigrum L. r, Pentalinum luteum (L.) Hansen & Wunderlin r; Inv. 3. Passiflora suberosa L. r; Inv. 5. Buchenavia tetraphylla (Aubl.) R.A. Howard (+), Schefflera morottoni (Aubl.) Maguire r, Thelypteris reticulata (L.) Proctor r, Guazuma ulmifolia L. r, Zyzygium jambos (L.) Alston r, Pisonia aculeata L. r; Inv. 6. Chromolaena odorata (L.) R.M. King & H. Rob. 1, Vernonia cinerea (L.) Less. r, Sida rhombifolia L. +, Canavallia sp. r, Stenorrynchus lanceolatus r; Inv. 7. Cyathea arborea (L.) Sm. +, Spondias mombin L. +, Alchornea latifolia Sw. r, Eugenia sp. +, Phaius tankervilliae (Banks) Blume r, Macrothelypteris torresiana (Gaudich.) Ching r, Solanum antillarum O.E. Schulz r, Campyloneurum phyllitidis (L.) C. Presl +, Guzmania monostachia (L.) Rusby ex Mez +, Paulinia sp. r, Lygodium volubile Sw. r.

Figure 2 Association Clidemio-Cyatheetum arboreae in north exposition.

Clidemio-Cyatheetum arboreae Reyes & Acosta ass. nov.

(Table 2, holotypus inv. 3.)

This phytocoenosis with 32.2 species average corresponding to an Homeostasis I developed in soils embrasure as results of an intramountain road build (Vía Mulata). This part of the road was made about 1988, extracted material were dumping down by the bulldozzer, with the objective to carry out big slopes for circulation flat.

This unstable group of rocks (schist) and soils (red and leach ferralitic) was quiet without vegetal protection, and for that rainfalls took up part of surface material, resulting in an irregular microrelief. Inclination is between 40 to 45 degrees and fundamental exposition is in north direction.

Actually is covered by a low canopy layer, between 8 and 12 m high with a cover of 90 to 100 %, predominantly composed by Cyathea arborea (L.) J. Sm., conforming the first stable cover. Although the cover is practically total, this fern has a thin foliage allowing light filtration inside the ecosystem. Isolated in this layer Piper aduncum L., Brunellia comocladifolia subsp. cubensis Cuatrec., Cecropia peltata, Trema micranthum (L.) Blume, Clidemia umbellata (Mill.) L.O. Wms. and occasionally Psydium guajava and Alchornea latifolia are present.

The shrub layer is variable, between 5 and 30 %, sometimes there are abundant species these are Cyathea arborea and Rhytidophyllum exsertum Urb.; Piper aduncum, Clidemia umbellata, Heliconia caribaea L., Guarea guidonia (L.) Sleumer are found too and occasionally Psychotria grandis Sw., Brunellia comocladifolia subsp. cubensis, Miconia prasina and Spondias mombin.

The herbaceous layer is the floral more diverse and cover between 70 and 90 %. More abundant species locally varying these are Nephrolepis brownii (Desv.) Hovenk. & Miyam., Desmodium axilare (Sw.) P. DC., D. triflorum (L.) P. DC., Miconia prasina, Begonia wrightiana A. DC., Oplismenus hirtellus subsp. setarius (Lam.) Mez ex Ekman, Rhytidophyllum exsertum, Blechnum occidentale L. and Thelypteris reticulata (L.) Proctor; with less cover other species are presents (Table 2).

In this community humus layer is not stabilized yet. The mainly fallen leaves contributed is Cyahea arborea, which provided an small, soft and easy discomposed material and hard woody foliage; due to the great slopes, intensity and high frequency of rainfalls that drag all the fine material, and for that there are only foliage traces of the before mentioned specie with irregular disposition, even over shrubs. It was studied 16-17.02.2004 (central territory N20⁰17,7ʹ, W74⁰42,4ʹ)

In addition to Table 2. Inv. 1. Hedyosmum nutans Sw. +, Fabaceae +, Guzmania monostachia (L.) Rusby ex Mez 1; Inv. 2. Ocotea leucoxylon (Sw.) Mez (r), Aiouea montana (Sw.) R. Rohde 1, Schefflera morototoni (Aubl.) Maguire. r, Campyloneurum brevifolium (Lood. ex Link) Link +, Cissus trifoliata L. +, Philodendrum lacerum (Jacq.) Schott 1, Miconia sp. r; Inv. 3. Clusia sp. r, Campiloneurum phillitidis (L.) C. Presl r, Citharexylum fruticosum L. r, Clethra cubensis A. Rich. r, Stachytarpheta cayennensis (L.C. Rich.) Vahl r; Inv. 4. Spondias mombin L. r, Scleria lithosperma (L.) Sw. +, Sticherus bifidus (Willd.) Ching r, Pavonia fruticosa (Mill.) Fawcett & Rendle r, Mikania micrantha Kunth r.

In Reyes et al.,³ was explicated the succesional stages; according the secondary one the Homeostasis I is an Early communities where an small group of heliophilous species close the canopy, creating for first time the conditions to permit entrance of mature community species and the disappearance of much stricter heliophilous.^15–17

Result an interesting thing how due the relativity favorable ecological conditions, mainly highest and frequent rainfalls, the community evolution is to fast in this territory, because of get this stage (Homeostasis I) had took between 12 and 16 years. Is too important how due the big inclinations of slopes and the quantity of rainfalls, in this stage the consistent develop of the humus layer is absent. The greater frequency of canopy species in Clidemio-Cyatheetum arboreae is due to be close to forest fragments, and for that the rain of seeds work efficiently.¹⁸

In the study two types of Homeostasis I with different dominant species are described due mainly to the exposition in these rainy places. While in the south slope Miconietum prasinae with two layers Miconia prasina prevailing were, in the north slope Clidemio-Cyatheetum arboreae for the main species Cyathea arborea in all three layers predominant were. The time since the beginning of this series until the Homeostasis I is considered between 12 and 16 years.

None.

There is no conflicts of interest.

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