The importance of weeds in ethnopharmacology.

Anthropogenic disturbance and tree diversity in Montane Rain Forests in Chiapas, Mexico

A general overview of the biological knowledge of the floristic province of the Tehuacan-Cuicatlan Valley in central-southern Mexico is presented. Floristic and faunistic richness and endemism, as well as uses of the flora are analyzed and discussed for this area, recently declared a biosphere reserve. The analysis shows that, in approximately 10 000 km2 the Tehuacan-Cuicatlan Valley contains between 10 and 11.4% of the Mexican flora. In addition, the valley possesses 365 endemic species that represent 13.9% of its flora. With respect to the fauna diversity, the available information is less comprehensive than for plants. Nevertheless, the study shows that the 11 species of amphibians, 48 species of reptiles, and 91 species of birds recorded for the valley surpasses the diversity found in other dry-lands of the world. In relationship to the mammals of the region, the available data are poor for most of the groups except for bats, for which 24 species have been reported. Regarding the use of the flora, the analysis revealed that 815 species are utilized by the people in the valley. A discussion related to future research activities is also included.

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Biological diversity in the Tehuacán-Cuicatlán Valley, Mexico

Land use and deforestation in the highlands of Chiapas, Mexico

Aim We aim to assess regional patterns in the distribution and species richness of vascular epiphytes with an emphasis on forests that differ in altitude and the amount of rainfall. Location Tropical America, in particularly the 75000 km2 large state of Chiapas in southern Mexico at 14.5-18.0o N. Chiapas is diverse in habitats with forests from sea-level to the tree-line at approximately 3800 m altitude and with annual amounts of rainfall ranging from 800 to over 5000 mm. It is also one of the botanical best-explored regions in the tropics. Methods First we give an overview of epiphyte inventories to date. Such epiphyte surveys were mostly carried out on the basis of surface area or individual trees and we discuss their problematic comparison. Applying a different methodological approach, next we used 12276 unique vascular epiphyte plant collections from Chiapas that are deposited in various botanical collections. The locality data were georeferenced and compiled in a relational database that was analysed using a Geographic Information System. To compare the number of species between inventories that differed in the numbers of records, we estimated the total richness, SChao, at each. Results We recorded 1173 vascular epiphyte species in 39 families (23 angiosperms), comprising c. 14% of all confirmed plant species in the state. About half of all species were orchids (568). Ferns and bromeliads were the next species rich groups with 244 and 101 species, respectively. Most species were found in the Montane Rain Forest and in the Central Plateau. Trees of different forest formations, rainfall regimes, altitudes and physiographic regions supported a characteristic epiphyte flora. Main conclusions We were able to confirm the presumed presence of a belt of high diversity at mid-elevations (500 - 2000 m) in neotropical mountains. In contrast to predictions, however, we observed a decrease in diversity when the annual amount of rainfall exceeded 2500 mm. The decrease is attributed to wind-dispersed orchids, bromeliads and Pteridophyta that may find establishment problematical under frequent downpours. In the wet but seasonal forests in Chiapas, this decrease is not compensated by plants in the animal-dispersed Araceae that are abundant elsewhere. We presume that in addition to the annual amount of rainfall, its distribution in time determines the composition of the epiphyte community.

Patterns in species richness and distribution of vascular epiphytes in Chiapas, Mexico

Flora of Chiapas Part 1. Introduction to the Flora of Chiapas@@@Flora of Chiapas Part 2. Pteridophytes

Two new species of Saurauia from Mexico are described, illustrated, and compared to their relatives. Saurauia madrensis occurs in cloud forests and Liquidambar forests of the Sierra Madre in Chiapas. Saurauia cana is found in wet forest habitats north of the trans-Mexican volcanic belt in the Sierra Madre Oriental. During the course of our work on the Flora of Chiapas, two unique taxa in Saurauia have come to light. Saurauia of Mexico and Central America has been treated monographically twice in this century (Bus- calioni and Muscatello 1912-1927; Hunter 1966). A third monograph treats the South American species (Soejarto 1980). Saurauias are wet forest trees and shrubs that have been confused because of cryptic and minute distinguishing characters. Large series of specimens are needed to delimit the entities. Authors of the two earlier treatments had access to very few specimens, and the two new species described herein were overlooked or confused with other more widespread species.

Dennis E. Breedlove

Papers

Flora of Chiapas Part 1. Introduction to the Flora of Chiapas@@@Flora of Chiapas Part 2. Pteridophytes

Two new species of Saurauia (Actinidiaceae) from Mexico.