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PACIFIC LOWLANDS, JALISCO:
|Location: Coastal Jalisco south-west of Guadalajara, between latitudes
19°22'-19°39'N and longitudes 104°56'-105°10'W.
Area: Region c. 350 km²; 131 km² in national-level Biosphere Reserve, 10.46 km² fully conserved.
Altitude: Region from sea-level to c. 500 m.
Vegetation: Fully conserved reserves mainly tropical deciduous forest, with some tropical semi-deciduous forest and riparian wetland.
Flora: High diversity, especially of woody plants; 1120 vascular plant species in 544 genera of 124 families known from region; c. 16% of station's species are regional endemics; threatened species.
Useful plants: Locally marketed fine or speciality woods (Cordia, Dalbergia, Guaiacum, Platymiscium, Swietenia); potential ornamentals.
Other values: Wild fauna, including many threatened species; scientific benchmark, scenery.
Threats: Agriculture, resort development, selective logging.
Conservation: National-level Biosphere Reserve, including Chamela Biological Station owned and protected by Universidad Nacional Autónoma de México (UNAM), Cumbres de Cuixmala Reserve owned and protected by Fundación Ecológica de Cuixmala.
Map 18: CPD Site MA7
This region of coastal Jalisco State is south of Puerto Vallarta near Chamela Bay and includes 350 km² in the municipality La Huerta. It is bounded to the west by the Pacific Ocean, to the north by the San Nicolás River, to the east (c. 10 km inland) by an arbitrary limit at about 500 m elevation and the Juan Gil-Rancho San Borja road, and to the south by the Cuitzmala River (which begins in the Sierra de Cacoma) (Map 18). Two adjacent forested reserves that are managed for full protection have been established in the region: Chamela Biological Station (3.46 km²) and Cumbres de Cuixmala Reserve (7 km²) (Lott 1993).
The region is within the Sierra Madre del Sur morphotectonic province, in the Pacific Coastal Plain (0-200 m) and the Pacific Ranges and Cuestas subprovinces (Ferrusquía-Villafranca 1993). Soils are volcanic; those of the hillsides are usually derived either from basalt or rhyolites (Bullock 1986). The region has hilly eroded plains with many small seasonal drainages and a few larger river valleys with permanent water. Only the San Nicolás and Cuitzmala rivers are major watercourses; the Chamela River has significant subterranean flow, but has surface flow only in occasional very wet years.
The mean annual precipitation was 707 mm in the period 1977-1983 (Bullock 1988; cf. Bullock and Solís-Magallanes 1990). The rainy season is only four months long, and the dry season is severe. Most rains (80%) fall between early July and early November, in some years with occasional December or January storms ("cabañuelas"). The mean annual temperature was 24.9°C over an 8-year period (1977-1984) (Bullock 1986), and monthly average temperatures varied from about 22.3°C in March to 27.3°C in May. Fire has not been important in this ecosystem.
The region's vegetation is dominated by tropical deciduous forest, with tropical semi-deciduous forest along drainages (arroyos). According to Rzedowski (1978), tropical deciduous forest originally occupied c. 8% of Mexico. His vegetation map designated a part of coastal Jalisco as thorn forest, which might be better classified as a secondary stage of tropical deciduous forest. The thorn forest covered a large part of coastal Sonora and Sinaloa and in isolated patches extended to the Balsas River Basin and the Isthmus of Tehuantepec, occupying c. 5% of Mexico (Rzedowski 1978).
The tropical deciduous forest is characteristic of the Pacific slope from the states of extreme southern Baja California Sur, Sonora and Chihuahua to Chiapas and onward into Central America. On Mexico's Atlantic slope, it is found mainly in three limited patches: in southern Tamaulipas and south-eastern San Luis Potosí, in central Veracruz, and on the Yucatán Peninsula. However, the Atlantic coast tropical deciduous forest is very poorly explored floristically, its affinities are uncertain, and it may be more physiognomically than floristically similar.
The Chamela station ecosystem includes solely tropical deciduous and semi-deciduous forests, and in this region the dry forest has its greatest diversity (Lott, Bullock and Solís-Magallanes 1987). The structure of the forest on hillsides is mostly a closed canopy of trees 4-15 m tall, with an understorey of shrubs and herbaceous species; in arroyos the trees are 8-25 m tall, in two strata (cf. Gómez-Pompa et al. 1994). There is high diversity in trees, shrubs and vines; very few herbaceous species occur within the closed forest and true annuals are rare (Lott 1993). There are few naturally occurring open areas except for ecotones. Many of the grasses and herbs found in disturbed areas may not be local natives.
A few significant plants carry on considerable photosynthesis during the long dry season - the abundance of four species of arborescent cacti [e.g. Pilosocereus (Cephalocereus) purpusii, Stenocereus chrysocarpus] is only apparent during the forest's leafless periods (cf. Bullock and Solís-Magallanes 1990). Visitors frequently remark on the preponderance of white tree trunks which are especially notable on some slopes in the dry season, when bark shedders in several families are also conspicuous (Brongniartia, Bursera, Caesalpinia, Celaenodendron, Jatropha, Psidium).
The Cumbres de Cuixmala Reserve includes a small area of riparian wetlands as well as the tropical deciduous and semi-deciduous forests (Rothschild, Lott and Sanders 1992; Lott 1993; cf. Gómez-Pompa et al. 1994). The heterogeneous riparian woodlands are 5-40 m high.
The region is in the Middle Serranías floristic province (Rzedowski 1978). A checklist of the vascular plants of the Chamela Biological Station has been prepared (Lott 1985) and a floristic survey of the Cuixmala reserve carried out (Rothschild, Lott and Sanders 1992). An annotated checklist of the Chamela Bay region includes both reserves and other habitats (Lott 1993). A Florula with keys and illustrations is planned. The most frequent families are Leguminosae, Euphorbiaceae, Compositae, Gramineae, Convolvulaceae and Malvaceae. The region is rich in species, with 1120 vascular plant species known, and supports a high level of endemism.
About 10% of the species may be endemic to coastal Jalisco and Colima or with some also in Michoacán. There is c. 16% regional endemism at the station (Lott 1985), since it does not include the marine coast or true riparian habitats where most of the more widely distributed species occur. Nearly 40% of the species in the flora are endemic to the dry forest of the Pacific slope, and 28% are restricted to Mexico (Lott 1993). Four genera are endemic to the Pacific coast: Chalema, Dieterlea, Celaenodendron and Mexacanthus. Celaenodendron mexicanum (Euphorbiaceae), the only species in its genus, has a very patchy coastal distribution and dominates a distinctive forest association that intergrades with the tropical deciduous forest in large patches of both reserves, which are important in protecting this species.
Because the region has only been easily accessible to settlement since a coast highway opened in 1972, there is no local tradition of useful plants. Many residents are from upland Jalisco or the neighbouring states (mostly Colima and Michoacán), and have brought common names and uses from their home areas for application to these sometimes different species; over 100 are used. Examples include a decoction of Plumeria rubra leaves used to relieve earache, Spondias purpurea fruits used in a drink, Stenocereus chrysocarpus fruits eaten as a delicacy and Hura polyandra used for wood, even though it can cause dermatitis. Hintonia latiflora and Physodium adenodes var. adenodes have ornamental potential.
Although the region's forests are not suitable for large-scale commercial logging, several timber species occur and their fine or regular woods are locally marketed: Cordia alliodora, C. dentata, C. elaeagnoides, C. seleriana, Dalbergia congestiflora, Guaiacum coulteri, Platymiscium lasiocarpum and Swietenia humilis. Already Celaenodendron mexicanum is a locally choice timber for roof beams and building posts.
These two fully protected forest reserves conserve representatives of a vegetation type highly threatened in Mexico by conversion to pastoral and agricultural uses (cattle, maize). The Mexican lands occupied by tropical deciduous forest have been considered poor, but are rapidly being deforested now because of the increasing human population. The conversion is highly destructive, since long-term sustainable production is not possible due to thin soils and lack of water except along river-valley bottoms, where the native vegetation (tropical semi-deciduous forest) already is almost totally gone.
There is tourist interest because the region has a spectacular coastline with beautiful beaches and is still relatively unspoiled, with interesting animals (particularly birds and sea-turtles) and plants. Controlled ecotourism offers one of the few long-term potentials. Typical tourism is of questionable viability because of competition from more established areas with easier access and greater availability of water. Several marginal or failed tourist centres and small real-estate developments exist in the area, and some have altered or drained salt marshes and mangrove swamps.
Of the 270 species of birds in the region, 40% are migratory and 60% resident. The Chamela Bay region is at the southern end of the North-west Mexican Pacific Slope Endemic Bird Area (EBA A05), which has seven species of restricted range. Two threatened species possibly occur within this CPD site: the yellow-headed parrot (Amazona oratrix), recorded from Chamela, and the Mexican woodnymph (Thalurania ridgwayi), known from only a handful of humid barrancas in western Mexico.
Many scientific papers and student theses have been produced at Chamela Biological Station, and long-term ecological studies are being carried out there (e.g. Bullock and Solís-Magallanes 1990) and at the Cumbres de Cuixmala Reserve. There are manuals of the mammals (Ceballos and Miranda 1986) and reptiles and amphibians (García and Ceballos 1994; Ramírez-Bautista 1994), a checklist of the avifauna (Arizmendi-A. et al. 1990) and lists, taxonomic treatments or natural histories of various insect groups (Atkinson and Equihua 1986; Morón 1988). Research on reforestation at the Cuixmala reserve, which had a 3-km² deforested area, was initiated in 1992. The proceedings of a 1991 symposium at the station on the ecology of tropical dry forests are forthcoming (Bullock, Mooney and Medina 1995).
Threats include burning and cutting, with conversion of neighbouring lands to pastoral and agricultural uses (although they are not very productive), and ecological isolation due to destruction of vegetation with the building of resort hotels, real-estate developments, polo fields and marinas.
Invasions and property disputes occur. Lack of perimeter access to monitor and prevent invasions has made the situation at Chamela more difficult, and is expected at Cuixmala. The selective hardwood exploitation may be causing or compounding problems for certain species: e.g. under Mexican law, Dalbergia congestiflora and Platymiscium lasiocarpum are considered endangered species and Guaiacum coulteri is a species subject to special protection (SEDESOL 1994); Celaenodendron mexicanum could become endangered from continuing use and further coastal development for tourism; and Swietenia humilis is in Appendix II of CITES.
Since 1971 the area of the Chamela Biological Station has been managed and protected by UNAM. The management has succeeded in resolving a long-term dispute with invaders and is committed to maintaining the station's integrity. The Cumbres de Cuixmala Reserve began in 1987 and has established an official status with the Mexican government.
At the end of 1993, a Chamela-Cuixmala Biosphere Reserve at the national level (covering 131 km²) was established by Presidential decree (Gómez-Pompa et al. 1994). In 1986 Playa de Cuixmala was decreed a Reserved Zone and Wildlife Refuge, but no coastal areas of the region are included in a fully protected Nature Reserve. It is highly desirable to fully conserve a portion of the remaining coastal palm forest, of Orbignya guacuyule. The status for protection of the Chamela Bay islands is unclear.
Arizmendi-A., M. del C., Berlanga, H., Márquez-Valdemar, L., Navarijo, L. and Ornelas, F. (1990). Avifauna de la región de Chamela, Jalisco. Universidad Nacional Autónoma de México (UNAM), Cuadernos del Instituto de Biología 4.
Atkinson, T.H. and Equihua, A. (1986). Biology of the Scolytidae and Platypodidae (Coleoptera) in a tropical deciduous forest at Chamela, Jalisco, Mexico. Florida Entomol. 69: 303-310.
Bullock, S.H. (1986). Climate of Chamela, Jalisco, and trends in the south coastal region of Mexico. Arch. Meteorol. Geophys. Bioklimatol. Ser. B 36: 297-316.
Bullock, S.H. (1988). Rasgos del ambiente físico y biológico de Chamela, Jalisco, México. In Morón, M.A. (ed.), La entomofauna de Chamela, Jalisco, México. Folia Entomol. Mex. Vol. 77. Pp. 5-17.
Bullock, S.H. and Solís-Magallanes, J.A. (1990). Phenology of canopy trees of a tropical deciduous forest in México. Biotropica 22: 22-35.
Bullock, S.H., Mooney, H.A. and Medina, E. (eds) (1995). Seasonally dry tropical forests. Cambridge University Press, Cambridge, U.K. 521 pp.
Ceballos, G. and Miranda, A. (1986). Los mamíferos de Chamela, Jalisco; manual de campo. UNAM, Inst. Biol., Mexico, D.F.
Ferrusquía-Villafranca, I. (1993). Geology of Mexico: a synopsis. In Ramamoorthy, T.P., Bye, R., Lot, A. and Fa, J.E. (eds), Biological diversity of Mexico: origins and distribution. Oxford University Press, New York. Pp. 3-107.
García, A. and Ceballos, G. (1994). Guía de campo de los reptiles y anfibios de la costa de Jalisco, México/Field guide to the reptiles and amphibians of the coast of Jalisco, Mexico. Fundación Ecológica de Cuixmala and UNAM, Inst. Biol., Mexico, D.F. 184 pp.
Gómez-Pompa, A. and Dirzo, R. with Kaus, A., Noguerón-Chang, C.R. and Ordoñez, M. de J. (1994). Las áreas naturales protegidas de México de la Secretaría de Desarrollo Social. SEDESOL, Mexico, D.F. 331 pp. Unpublished.
Lott, E.J. (1985). Listados florísticos de México, III. La Estación de Biología Chamela, Jalisco. UNAM, Inst. Biol., Mexico, D.F. 47 pp.
Lott, E.J. (1993). Annotated checklist of the vascular flora of the Chamela Bay region, Jalisco, Mexico. Occas. Pap. Calif. Acad. Sci. No. 148. 60 pp.
Lott, E.J., Bullock, S.H. and Solís-Magallanes, J.A. (1987). Floristic diversity and structure of upland and arroyo forests in coastal Jalisco. Biotropica 19: 228-235.
Morón, M.A. (ed.) (1988). La entomofauna de Chamela, Jalisco, México. Folia Entomol. Mex. Vol. 77. 525 pp.
Ramírez-Bautista, A. (1994). Manual y claves ilustradas de los anfibios y reptiles de la región de Chamela, Jalisco. UNAM, Cuadernos del Instituto de Biología 23.
Rothschild, B.M., Lott, E.J. and Sanders, A.C. (1992). A report to the Fundación Ecológica de Cuixmala on the floristic surveys of 1990-1991 of the Cuixmala-Cumbres and El Jabalí reserves in Mexico. University of California, Riverside, U.S.A. and IUCN, Richmond, U.K. 134 pp.
Rzedowski, J. (1978). Vegetación de México. Editorial Limusa, Mexico, D.F. 432 pp.
SEDESOL (Secretaría de Desarrollo Social) (1994). Norma Oficial Mexicana NOM-059-ECOL-1994, que determina las especies y subespecies de flora y fauna silvestres terrestres y acuáticas en peligro de extinción, amenazadas, raras y las sujetas a protección especial, y que establece especificaciones para su protección. Diario Oficial de la Federación 16/05/94: 2-60.
This Data Sheet was written by Emily J.
Lott (University of California, Department of Botany and Plant Sciences, Riverside, CA
Beth M. Rothschild (Botanic Gardens Conservation International, Kew, U.K.) served as liaison with the Cumbres de Cuixmala Reserve.
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