According to Dinerstein et al.'s classification (1995), the biotope belongs to the Tehuantepec Moist Forest Ecoregion. The map of functional landscapes of the MBR (CONAP, 2001a), shows that the predominant habitat of the protected area is a high and medium broad-leaved forest in the South, and a lowland forest in the southeast.
The Rapid Ecological Evaluation of the MBR (APESA, 1993) classifies the area as a forest with an average diversity of trees, perhaps 200 species per hectare; Schulze and Whitacre (1999) estimate that the adjacent Tikal Park has more tree species. The soil drainage of the rolling grounds promotes varied vegetation. As occurs in habitats of other parts of the MBR, the temporary flooded areas have lowland forest features, with very compact and sometimes spiny bushes.
High and medium broad-leaved forest
These types of forests dominate the protected area. Soils drain very quickly because they are shallow and porous. The uppermost canopy is between 6 and 20 meters tall (CONAP, 2001a), depending on the conditions. In some well-drained places, the uppermost canopy is tall but sparse, and some trees lose their leaves during the driest seasons. Trees are not as tall in places exposed to the elements and the sun, and hilltops are covered with shrub formations. In the lower areas, vegetation is more abundant and species more varied (Pérez et al., 2001). Some individual trees are 25 or more meters tall and protrude from the canopy. The Breadnut Tree or Ramón (Brosimum alicastrum) is abundant and seems associated to other species such as Sapodilla (Pouteria reticulata), Yellow Mombin or Jobo (Spondias mombim), Copal Tree (Protium copal), and Noseberry (Manilkara zapota), also plentiful (Pérez et al. ibid.) The forest harbors several commercial species such as Mahogany (Swietenia macrophylla) and Cedar (Cedrela odorata), which are favored by illegal extractors. The high and dark understory abounds in Corozo (Orbignya cohune), Bay Leaf (Sabal morrisiana), "Xate" (Chamaedorea sp), and "Bayal" (Desmoncus ferox) palms.
This type of forest covers the southern corner of the protected area. It flourishes in deep, heavy, and sticky soils that flood during the rainy season and dry up and crack during hot periods. Forests have grown in ravines or small or medium lowlands. Soils drain poorly and are constantly under water during the rainy season. Water pools up in depressed grounds, which give way to plant formations. A low, sparse treetop forest is evident in some places, where Logwood (Haematoxylum campechianum) predominates. Other species of this formation include Black Olive (Bucida buceras) and "Palo Gusano" (Lonchocarpus guatemalensis). The canopy of lowland forests rarely grows beyond 11m.
These are the findings of the latest inventories carried out in the Cerro Cahuí Protected Biotope: 29 mammal, 11 amphibian, 17 reptile, and 82 bird species (Pérez et al., 2001), which are very discouraging figures when compared to neighboring areas such as Tikal National Park and the "San Miguel la Palotada" Biotope. This difference might be due to incomplete research or the fact that the biological diversity is degrading because of isolation and human pressure inside the Biotope and surrounding areas. Jaguars (Panthera onca) have been observed in the area, as well as four bat species (Trachops cirrhosus, Mimon bennettii, Micronycteris megalotis and Tonatia saurophila) and these sightings indicate that the forests are mature and that the area is still in good state.
Among the regional endemic fauna that inhabits the biotope, the howler monkey (Alouatta pigra) and the crocodile (Crocodylus moreletii) are associated to Lake Petén Itzá, which is adjacent to the protected area. The Central American river turtle (Dermatemys mawii) has also been observed in the area. Thirteen of the bird species reported by Pérez et al., 2001 are included in CONAP's Red List (CONAP (2001b). A. pigra, D. mawii, P. onca, and C. moreletii have been added to UICN's red list, the first two as endangered. Among the flora species, Mahogany (Swietenia macrophylla) appears in CITES' Appendix II, while CONAP's Red List of Flora (2001c) considers that many species in the area could become extinct if extraction is not regulated.