Nelson Zamora

Contrasting Hurricane Damage in Tropical Rain Forest and Pine Forest

When Hurricane Joan struck the southeastern coast of Nicaragua on 22 October 1988, with winds exceeding 250 km/h (Cortes and Fonseca 1988), it severely damaged several different kinds of tropical forest. These included the Pinus caribaea forest typical of eastern Honduras and Nicaragua (Clewell 1986) as well as the broad-leaved rain forest found along the Caribbean coast of most of Central America. Although occurring in similar climates, these forests are quite different in structure: the pine forest has a single dominant coniferous species, while the rain forest has hundreds of angiosperm tree species sharing dominance. In this note we describe the differing effects of Hurricane Joan on the physical structures of two kinds of tropical forest.

Post-agriculture versus post-hurricane succession in southeastern Nicaraguan rain forest

Wecompared five-year old forests developing after agriculture to those recoveringfrom Hurricane Joan (1988) and to the pre-hurricane forest, at two sites intropical rain forest in southeastern Nicaragua. We used non-parametric clusteranalysis to group transects by their species compositions, and compared theirspecies richness, estimated total species richness, dominance, density andbasalarea. Post-agriculture transects showed distinctive species compositions andlower diversity than post-hurricane transects, which were in turn more similarto the pre-hurricane forest. These results are similar to those found by otherresearchers in the Amazon and in Puerto Rico. Land use history was moreimportant than proximity in the landscape in determining the composition andstructure of post-disturbance forests in this region.

Nyssa talamancana (Cornaceae), an addition to the remnant Laurasian Tertiary flora of southern Central America

A new species,Nyssa talamancana, with fruits larger than those of any other, either living or fossil, is described from Costa Rica and Panama. In size, number of germination valves, and surface-sculpturing, its endocarps resemble those of the fossil assemblage more than those of the other living species. The occurrence of this distinctive new member of a definitely Laurasian family, in association with other endemic or nearly endemic Laurasian taxa, at wet mid-elevations lends credence to the idea that these forests harbor remnants of the really ancient flora of southern Central America.

SEPARATION OF CRUDE PLANT EXTRACTS WITH HIGH SPEED CCC FOR PRIMARY SCREENING IN DRUG DISCOVERY

High speed countercurrent chromatography (HSCCC) was used in a pre-fractionation pilot study to improve the quality of crude plant samples for primary screening in drug discovery efforts. The methanol extracts of sixty-four plant samples were (i) defatted, (ii) treated with poly-N-vinylpyrrolidone (PVP) for polyphenolic removal, and (iii) fractionated with a multilayer coil planet centrifuge. The ternary solvent system CH2Cl2:MeOH:H2O (5:6:4, v/v/v) was used based upon elution of known plant natural product standards with ranging polarities. Elution was carried out until a partition coefficient (K) of 1, followed by column contents extrusion to exploit stationary phase separation and to increase the polarity range of compounds, fractionated. Fractionation was found to be consistent for all separated extracts with respect to sample recovery, stationary phase fraction (Sf), and weight distribution by fraction number. Biological evaluation was conducted in 20 mechanism-based, in-vitro assays with an evaluation of biodata trends. Bioassay interfering agents such as polyphenolics and fatty acids were chromatographically localized and rapidly identified.

Ruptiliocarpon (Lepidobotryaceae): A New Arborescent Genus and Tropical American Link to Africa, with a Reconsideration of the Family'

A new genus and species of trees from Costa Rica and northern South America, Ruptilio- carpon caracolito, is described and compared to the African Lepidobotrys. It is distinguished from Lepidobotrys primarily by its much shorter fila- ments, basifixed rather than versatile anthers, its lack of styles, its two-rather than three-locular ova- ry, and by its irregularly dehiscent fruits with a woody exocarp and cartilagineous endocarp. In wood anatomy, apart from the presence of vestured pits in Ruptiliocarpon, the two genera are remarkably similar. They match in important floral and fruit characteristics (dioecious; 5 + 5 stamens of unequal length with filaments fused at base; two apical, col- lateral ovules per locule; one-seeded fruit; black seed with a large red aril and no endosperm), and both have unifoliolate leaves with very fugaceous stipules and stipels, and leaf-opposed inflorescences. The familial placement of Lepidobotrys has been con- troversial: the genus was placed first in the Linaceae by Engler, then in the Oxalidaceae by Hallier, then in its own family (between Linaceae and Erythrox- ylaceae) by Leonard, and then again in the Oxali- daceae by Cronquist. Reviewing evidence, old and new, we maintain Ruptiliocarpon and Lepidobo- trys (only) in the Lepidobotryaceae and suggest that they relate more to Sapindales or possibly Euphor- biaceae than to Oxalidaceae.

Mucuna tapantiana (Fabaceae: Faboideae: Phaseoleae), a new species from Costa Rica

Summary. A new species of Mucuna (Fabaceae: Faboideae: Phaseoleae), endemic to Costa Rica, is described and illustrated. Mucuna tapantiana is distinguished by its small, essentially glabrous leaflets, conspicuous filiform peduncle and pedicels, inflorescences with few green or yellowish-green flowers; fruits with softly villous, yellowish or brownish pubescence on the outer surface (when fresh), but without urticating trichomes, turning dark brown or blackish when dry, 1 – 2-seeded; seeds oblong and laterally compressed.

Can Timber Production Be Compatible with Conservation of Forest Biodiversity?–Two Case Studies of Plant Biodiversity in Managed Neotropical Forests

SUMMARY. A variety of practices can greatly diminish the impacts of forest management on biodiversity. A case study from a subtropical humid forest reserve in Misiones, Argentina is presented to illustrate a “uniform spacing” method of forest harvest. In this method, trees are selected for extraction or marked for retention according to their scarcity, their horizontal distribution, and their characteristics to serve as seed trees. Three years after harvesting, the forest cut by uniform spacing had the highest density of seedlings of total as well as commercial species, and it also exhibited high diversity of understory plants other than trees. A case study of a silvicultural experiment carried out by CATIE in Costa Rica is also presented, focusing on the effects of logging and post-harvest silvicultural treatments on forest species richness and composition during the first 6-7 yr following logging and 5 yr following the application of treatments. The forest studied was shown to exhibit marked compositional variation in relation to a topographical gradient after the implementation of the experiment; such □ or ecosystem diversity should be taken into account in all future evaluations of the effect of forest management on plant biodiversity. Post-harvest silvicultural treatments caused an immediate reduction in species-richness = 10 cm dbh in 1.0 ha due to the chance elimination of species represented by one or a small number of individuals in the plots, and may affect overall species composition in the medium term as they are directed to favoring commercial species by decreasing competition from non-commercial species. Species richness declined under both silvicultural treatments, however, no changes of species-richness or composition as a result of silvicultural treatment were evident in the forest understory (individuals 2.5-9.9 cm dbh). The only detectable changes in understory plant biodiversity were caused by the felling and extraction of timber, and these changes were restricted to the very localized areas disturbed by these management operations. The application of low-intensity logging methods with selection of remnant trees requires detailed pre- and post-harvest forest inventories and follow up of treatments to ensure successful regeneration and growth of desired species. The Costa Rican study shows that different forest management operations (logging and silviculture in this case) may have different effects on plant biodiversity; this perspective should be applied to future studies in order to better understand the balance between production and conservation in tropical forests. Long-term follow up is needed to assess the true effects of forest management on biodiversity, including natural regeneration as well as growth dynamics of trees, until a whole harvest cycle is completed.

Notes on Swartzia (Leguminosae) in Central America preliminary to the Flora Mesoamericana, with descriptions of two new species from Costa Rica

In preparation of a treatment of Swartzia (Leguminosae) for the Flora Mesoamericana, recent updates to the taxonomy of the genus in Central America are discussed, and two new species from the Pacific slope and lowlands of central and southern Costa Rica are described and illustrated. One of them, S. picramnioides, is a member of the section Possira and is closely related to S. standleyi of Guatemala and Belize and to the South American species S. myrtifolia. The other, S. zeledonensis, belongs to the Central American apetalous clade of section Terminales. It is probably most closely related to the Panamanian species, S. nuda. We conclude that Swartzia is represented in Mexico and Central America by 14 species and provide a key for their identification.ResumenComo parte de la preparación del tratamiento del género Swartzia (Leguminosae) para la Flora Mesoamericana, taxonomía actualizada del mismo para Centroamérica es discutida y dos nuevas especies de los vertientes pacíficos y tierras bajas del centro y sur de Costa Rica son descritas e ilustradas. Una de ellas, S. pricramnioides, es un miembro de la sección Possira y está cercanamente relacionada con S. standleyi de Guatemala y Belice y con la especie Suramericana S. myrtifolia. La otra, S. zeledonensis, pertenece al clado apetalo centroamericano de la sección Terminales. Es probablemente, más cercanamente relacionada a la especie panameña S. nuda. Concluimos que Swartzia esta representado en México y Centroamérica por 14 especies y proveemos una clave para su identificación.