Cozumel Island
BIOLOGICAL CHARACTERISTICS
5. Vegetation.
5.1. Jungles.
5.2. Mangroves
5.3. Vegetation of coastal dunes.
5.4. Palm grove.
5.5. Popal-Tular.
5.6. Cultivated grassland.
5.7. Type of Vegetation.
6. Fauna.
6.1. Mammals.
6.2. Birds.
6.3. Reptiles.
5. Vegetation.
5.1. Jungles.
The types of jungles present in the Reserve are the medium subdeciduous jungle and the low deciduous jungle, with the first being the predominant vegetation type and concentrating in the central portion of the protected natural area. The medium subdeciduous jungle is characterized by developing in warm subhumid regions, preferably in climates of the Aw type, on very shallow soils with little organic matter.
Its structure consists of trees from 8 to 20 meters in height, with a scarce shrub-herbaceous stratum, and about 50% of the species are deciduous. The dominant species in this type of vegetation are: Chicozapote (Manilkara zapota), chaka’ (Bursera simaruba), barbas de viejo (Calliandra belizensis), chechem (Metopium brownei), ya’ axnik (Vitex guaumeri), ceiba (Ceiba pentadra), tzalam (Lysiloma latisilicua) and caracolillo (Mastichodendron foetidissimum) (Téllez-Valdéz y Cabrera-Cano, 1987; Téllez Valdés et al. 1989; Martínez-Morales, 1996; Carabias et al. 1998, citados por Caballero, 2007).
The low deciduous jungle is the transition vegetation between coastal dune vegetation and/or mangroves, and the medium subdeciduous jungle. It develops in warm subhumid climates, predominantly the Aw. It has a tree stratum from 8 to 12 m high and a shrub layer without herbs. The dominant plants for this type of vegetation are: Chiimtook (Enriquebeltrania crenatifolia), chakchucum (Pithecellobium mangense), guamúchil (P. dulce) and uchiche (Diospyros nicaraguensis) (Téllez-Valdéz y Cabrera-Cano, 1987; Téllez-Valdés et al. 1989; Martínez-Morales, 1996; Carabias et al. 1998, citados por Caballero, 2007).
5.2. Mangroves.
Mangroves correspond to the tree and shrub vegetation of the tidal zone in tropical and subtropical regions. They are plants adapted to live in stressful conditions in floodable soils, as well as variations in salinity, temperature, and pH.
These ecosystems correspond to the ecotone between marine and terrestrial environments, so they are functionally related to jungles, seagrasses, and coral reefs; being of great importance for the proper functioning of the coastal zone. The mangrove species recorded in the Reserve correspond to: Red mangrove (Rhizophora mangle), white mangrove (Laguncularia racemosa), black mangrove (Avicennia germinans), and button mangrove (Conocarpus erectus) (Herrera-Silveira, et al., 2008), all considered threatened in the NOM-059-SEMARNAT-2010.
The areas where this plant community is registered within the Reserve are the southeast and east, in the locations known as Punta Chiqueros and Punta Morena respectively, and in the northeastern limit, near the town of Punta Molas. Herrera Silveira and collaborators (2008) point out that the mangroves of Cozumel Island are of a special type given the peculiarities in the structure of the vegetation, as well as their adaptive response to the conditions and characteristics of each specific site such as hydrological conditions, sediments, as well as the effects of hurricanes and variations in precipitation.
This type of vegetation, on Cozumel Island, is extremely important for the conservation of the endemic raccoon (Procyon pygmaeus) since several studies (Cuarón et al., 2004; MacFadden, 2004; García Vasco, 2005; Copa-Álvaro unpublished data) have found that in these sites the population of this species, although small, is stable and there is evidence of reproduction. Similarly, they serve as feeding, shelter, reproduction, and breeding sites for species of invertebrates, fish, and resident and migratory birds (Franquesa, et al., 2007)
5.3. Vegetation of coastal dunes.
Coastal dune vegetation is subject to a wide range of environmental conditions unfavorable for its establishment and development. It has been classified as halophytic vegetation, which develops in soils with a high content of soluble salts, and which can assume diverse forms, floristically and structurally. They can be dominated by species with herbaceous, shrubby, and even arboreal forms. They are located along the coastline and, according to the tolerance ranges of biotic and abiotic factors, such as salinity and soil stability, they are divided into two main types known as the pioneer zone, located near the coastline, and the shrub zone, which is located within the dune (Miranda, 1978, Rzedowki, 1981, Espejel, 1984, cited by Torres, et al., 2010).
The pioneer zone is composed of shrubby or herbaceous forms erect and prostrate among them: the riñonina (Ipomoea pes-carpe), sea grape (Coccoloba uvifera), sikimay (Tourneiforita gnaphalodes), beach lily (Hymenocallis americana), jmul (Cenchrus echinatus), k’an lol xiw (Flaveria linearis), sea daisy (Ambrosia hispida), cakile maritima (Cakile edentula), and chit palm (Thrinax radiata). Of these, the first three are the most frequent and are even pioneers in rocky places. The shrub zone is composed of erect and prostrate shrubby or herbaceous forms integrated by Agave angustifolia, Acanthocerus tetragonus, sea grape (Coccoloba uvifera), chit palm (Thrinax radiata), and nakas palm (Coccothrinax readii - endemic species), the latter listed as threatened within the NOM-059- SEMARNAT-2010. In the Reserve, this plant community can be observed on its southeast coast (Franquesa, et al., 2007; CONANP, 2013).
The role of this plant community is fundamental since it provides important environmental services, being one of the most relevant its function as a protective barrier against the action of winds and tides, its contribution to soil formation through the accumulation of sand, thereby preventing coastal erosion, and as a habitat that provides shelter, food, and protection to numerous species of insects, reptiles, birds, and mammals.
5.4. Palm grove.
It is an association of little diversity or monospecific, it develops in periodically or permanently flooded, from 3 to 10m tall, in some cases related to other communities such as tular, saibal. They mostly consist of tasiste (Acoelorhaphe wrighti), but also present are Cladium jamaicense, Acrostichum danaeifolium, Schomburgkia tibicinis, Dichromena colorata, and Elaeocharis caribaea as accompanying species. There are also significant populations of chit palm (Thrinax radiata), a threatened species according to NOM-059- SEMARNAT-2010 (Franqueza, et al., 2007).
5.5. Popal-Tular.
They are xeral associations that inhabit periodically or permanently flooded, muddy, somewhat firm soils, and sometimes with brackish waters and are usually associated with coastal lagoon areas. Its composition is dominated by Typha dominguensis or Cladium jamaicense with some more elements in the ecotones with other associations such as: Acrostichum danaeifolium, Dalbergia brownei, and Rhabdadenia biflora. This type of vegetation can be observed on the east coast of the Reserve (Franquesa, et al., 2007).
5.6. Cultivated grassland.
This type of vegetation corresponds to that which has been intentionally introduced into a region, and for its establishment and care, some cultivation and management work is carried out. They are grass species from different parts of the world such as Pangola grass (Digitaria decumbens), buffel grass (Pennisetum ciliaris), guinea grass (Panicum maximum), among many others. These grasslands are generally the ones that form the so-called pastures in tropical areas (INEGI, 2009).
The representative characteristics of the types of jungle present in Cozumel, low, medium, and high subperennial, are shown in the following table.
5.7. Type of Vegetation
a) Low subperennial jungle.
25 to 75 percent of the species lose their leaves in the dry season, reaching heights of between 5 and 15 meters with diameters not exceeding 50 centimeters, it is found in the central part of the island.
b) Medium subperennial jungle.
10 to 50 percent of the species lose their leaves in the dry season, reaching heights of between 15 and 25 meters with diameters between 50 and 100 centimeters, it is found in the central part of the island.
c) High subperennial jungle.
Less than 10 percent of the species lose their leaves in the dry season, reaching heights greater than 25 meters with diameters greater than 100 centimeters, it is located in the northern and eastern part of the island.
This classification is based on the results obtained by the National Institute of Statistics, Geography and Informatics (INEGI), through the detailed cartography of the use of land and vegetation cover, at a scale of 1:50,000 (INEGI, 2009).
6. Fauna.
6.1. Mammals.
In the Cozumel Jungle and Wetlands State Reserve, 17 species of mammals are registered, of which 7 are endemic to Cozumel Island. With the exception of the opossum (Didelphis marsupialis cozumelae) and the collared peccary (Pecari tajacu nanus), the remaining species are categorized under some level of protection according to NOM-059-SEMARNAT-2010 as follows: Cozumel Raccoon (Procyon pygmaeus; endangered), Cozumel Harvest Mouse (Reithrodontomys spectabilis; threatened), Cozumel Coati (Nasua narica nelsoni; threatened), Cozumel Marsh Rice Rat (Oryzomys couesi cozumelae; threatened), Cozumel White-footed Mouse (Peromyscus leucopus cozumelae; threatened). Cozumel Raccoon (Procyon pygmaeus): This species differs from its mainland counterpart (Procyon lotor) by its smaller body size, skull, and teeth. It has a broad black band covering the lower part of the neck, a tail with a golden yellow color, and a rounded, posteriorly widened snout.
It has also been found in Mayan archaeological remains, where the bones confirm the reduced size of the individuals. The habits of this species are clearly nocturnal, and it prefers areas with mangroves and sandy soils (Cuarón, et al., 2004, cited by Franquesa, et al., 2007). Cozumel Coati (Nasua narica nelsoni): The differences this species presents compared to the mainland coati (N. narica) are mainly its smaller body and skull size, as well as a more graceful morphology, which is a trend observed in island fauna.
Both the remains found in Mayan archaeological sites dating from 100 to 1500 AD and observations by local residents today indicate that this procyonid species was much more abundant in the past, especially before Hurricane Gilbert. Although this species is typical of jungles and has been observed in the semi-deciduous jungle surrounding the San Gervasio archaeological site adjacent to the wetlands of the north coast, its presence or incursions into that wetland area cannot be ruled out, as there are records in areas with vegetation of that type (Cuarón, et al., 2004, cited by Franquesa, et al., 2007). Collared Peccary (Pecari tajacu nanus): Among the medium-sized mammals of Cozumel, this species is the most abundant in relative terms (Cuarón et al., unpublished data, cited by Franquesa, et al., 2007). It is considered a distinct subspecies from the one found on the mainland, with a smaller size and a black nose.
Of all the islands in the Caribbean, only Cozumel and Trinidad have native individuals of this species (of the subspecies in the former case) (Franquesa, et al., 2007). Cozumel Harvest Mouse (Reithrodontomys spectabilis): It is an endemic rodent of Cozumel Island (Jones and Lawlor, 1965, cited by Franquesa, et al., 2007).
It is currently an extremely scarce mouse, absent in large areas of the island (Gutiérrez Granados, 2003; Fortes 2004, cited by Franquesa, et al., 2007). Additionally, its populations show marked temporal fluctuations, making it vulnerable. It seems to have an important ecological function in the regeneration of the Cozumel jungle, with a positive relationship between its abundance and the species richness of seedlings (Gutiérrez Granados, 2003, cited by Franquesa, et al., 2007).
As an anti-predatory behavior, it is active during moonless nights but has no activity during the bright phase (full moon) of the month (Fortes, 2004, cited by Franquesa, et al., 2007). Cozumel White-footed Mouse (Peromyscus leucopus cozumelae): It was the most common mammal species on the island in the mid-1980s (Engstrom et al., 1989, cited by Franquesa, et al., 2007). However, despite a large sampling effort initiated in 2001, distributed in sites throughout the island, the species has not been found again, and everything indicates that it is extinct (Gutiérrez Granados, 2003; Fortes 2004; Cuarón et al., unpublished data, cited by Franquesa, et al., 2007). Since there are large portions of suitable habitat for the species on the island, the extinction of this rodent seems to be linked to predation by feral dogs and cats, and especially by Boa constrictor (Franquesa, et al., 2007).
6.2. Birds.
The bird fauna of the Reserve is composed of 271 species (Berlanga, et al., 2008), including resident and migratory birds, of which 19 are exclusive to the island. Some are mentioned in NOM-059-SEMARNAT-2010 for being in some risk status: Cozumel Attilla (Attila spadiceus cozumelae; subject to special protection), Cozumel Roadside Hawk (Buteo magnirostris gracilis), Northern Cardinal (Cardinalis cardinalis saturatus), Cozumel Emerald Hummingbird (Chlorostilbon forficatus), Cozumel Rufous-browed Vireo (Cyclarhis gujanensis insularis; subject to special protection), Yellow Warbler (Dendroica petechia rufivertex), Golden-fronted Woodpecker (Melanerpes aurifrons leei), Cozumel Woodpecker (Melanerpes pygmaeus pygmaeus), Cozumel Black Catbird (Melanoptila glabrirostris cozumelana; subject to special protection), Yucatan Flycatcher (Myiarchus yucatanensis lanyoni), Blue-gray Gnatcatcher (Polioptila caerulea cozumelae), Stripe-headed Tanager (Spindalis zena benedicti), Cuban Grassquit (Tiaris olivaceus intermedius), House Wren (Troglodytes aedon beani; subject to special protection), and Cozumel Vireo (Vireo bairdi; threatened). The Cuitlacoche (Toxostoma guttatum) and the Cozumel Curassow (Crax rubra griscomi) deserve special attention, both endemic species and endangered (NOM-059-SEMARNAT-2010), which use the semi-deciduous jungle as habitat.
The Cuitlacoche is the only species of its genus in southeastern Mexico, making its conservation even more important (Franquesa, et al., 2007). Among the birds mentioned in some risk status, without being endemic, are: White-crowned Pigeon (Patagioenas leucocephala; threatened), Yucatan Parrot (Amazona xantholora; threatened), Peregrine Falcon (Falco peregrinus; subject to special protection), Painted Bunting (Passerina ciris; subject to special protection), Zenaida Dove (Zenaida aurita; subject to special protection). Macouzet and Escalante Pliego (2013) report three new records of migratory species for the Reserve, Alder Flycatcher (Empidonax alnorum), Blue-headed Vireo (Vireo solitarius), and White-crowned Sparrow (Zonotrichia leucophrys); and they highlight the importance of the island's ecosystems as a temporary stopover site for migratory birds.
6.3. Reptiles.
There are 27 species of reptiles registered in the Reserve, of which 14 are in some risk category according to NOM-059-SEMARNAT-2010. Among them are the American Crocodile (Crocodylus acutus; subject to special protection), Striped Spiny-tailed Iguana (Ctenosaura similis; threatened), Yucatan Mud Turtle (Rhinoclemmys areolata; threatened), Scorpion Mud Turtle (Kinosternon scorpioides; subject to special protection), Western Ribbon Snake (Thamnophis proximus; threatened); in the marine part are the Loggerhead Turtle (Caretta caretta; endangered), Hawksbill Turtle (Eretmochelys imbricata; endangered), and Green or White Turtle (Chelonia mydas; endangered).
The Boa Constrictor is a species indicated by the aforementioned norm as threatened, however, this is an introduced species on the island and is currently one of the main predators of the native and endemic fauna of Cozumel (Martínez Morales and Cuarón, 1999; Romero-Nájera 2004; González-Baca, 2006; Romero-Nájera et al., in press, cited by Franquesa, et al., 2007).
The endemic species recorded in this group are the Cozumel Whiptail (Aspidoscelis cozumela) and the Cozumel Spiny-tailed Lizard, the latter subject to special protection (NOM-059- SEMARNAT-2010). The Black-headed Forest Racer (Dryadophis melanolomus) and the Black-bellied Centipede Snake (Tantilla moesta) are species reported as new records (González-Baca, 2006).