Monday, September 29, 2008
Interacting effects of canopy gap, understory vegetation and leaf litter on tree seedling recruitment and composition in tropical secondary forests
Resumen : We experimentally investigated interacting effects of canopy gaps, understory vegetation and leaf litter on recruitment and mortality of tree seedlings at the community level in a 20-year-old lowland forest in Costa Rica, and tested several predictions based on results of previous studies. We predicted that experimental canopy gaps would greatly enhance tree seedling recruitment, and that leaf litter removal would further enhance recruitment of small-seeded, shade-intolerant seedlings in gaps. We created a large (320-540 m²) gap in the center of 5 out of 10 40 m x 40 m experimental plots, and applied the following treatments bimonthly over a 14-month-period in a factorial, split-split plot design: clipping of understory vegetation (cut, uncut), andleaf litter manipulations (removal, addition, control). As expected, experimental gaps dramatically increased tree seedling recruitment, but gap effects varied among litter treatments. Litter addition reduced recruitment in gaps, but enhanced recruitmentunder intact canopy. Species composition of recruits also differed markedly between gap treatments: several small-seeded pioneer and long-lived pioneer species recruited almost exclusively in gaps. In contrast, a few medium-to-large-seeded shade-tolerantspecies recruited predominantly under intact canopy. Leaf litter represents a major barrier for seedling emergence and establishment of small-seeded, shade-intolerant species, but enhances emergence and establishment of large-seeded, shade-tolerant species, possibly through increased humidity and reduced detection by predators. Periodic clipping of the understory vegetation marginally reduced tree seedling mortality, but only in experimental gaps, where understory vegetation cover was greatly enhanced compared to intact canopy conditions. Successful regeneration of commercially valuable long-lived pioneer trees that dominate the forest canopy may require clear-cutting, as well as weeding and site preparation (litter removal) treatments in felling clearings. Management systems that mimic natural canopy gaps (reduced-impact selective logging) could favor the regeneration of shade-tolerant tree species, potentially accelerating convergence to old-growth forest composition. In contrast, systems that produce large canopy openings (clear-cutting) may re-initiate succession, potentially leading to less diverse but perhaps more easily managed "natural plantations" of long-lived pioneer tree species
Palabras claves : Seedling recruitment and mortality ;Short- and long-lived pioneer tree ;Canopy gap ; Understory vegetation ; Leaf litter ;Secondary succession.
Biblioteca OET: NBINA-8944
Lücking, R.; Chaves-Chaves, J.L.; Sipman, H.J.M.; Umaña-Tenorio; L.; Aptroot, A. 2008. A first assessment of the Ticolichen biodiversity inventory in Costa Rica: The genus Graphis, with notes on the genus Hemithecium (Ascomycota: Ostropales: Graphidaceae). Fieldiana. Botany 47: 1-126.
Resumen : The genus Graphis sensu Staiger is treated as a further contribution to the TICOLICHEN biodiversity inventory in Costa Rica. Graphis s.str. is the largest tropical lichen genus, with more than 300 accepted species worldwide, and also the largest in Costa Rica, with a total of 115 species recognized in this work.
(Graphis gomezii Lücking, Will-Wolf & Umaña, sp. nov. Holotype. COSTA RICA. Alajuela: Volcán Tenorio National Park. ETYMOLOGY—This new species is dedicated to Luis Diego Gómez, esteemed colleague, mentor, and friend, and one of the most outstanding botanists and naturalists of Costa Rica and Latin America)
Palabras claves : Lichenes; Fungi; New species.
Biblioteca OET: NBINA-8962
Lücking, R. 2008. Foliicolous lichenized fungi. Flora Neotropica, Monograph no. 103, 867 p.
Resumen : Se describe una nueva familia, Lyrommataceae Lücking, cuatro nuevos géneros, Baflavia Lücking, Brasilicia Lücking, Kalb & Sérus., Eugeniella Lücking & Sérus., y Phyllogyalidea Lücking & Aptroot, y una nueva sección,Badimia sect. Pseudogyalecta (Vézda) Lücking & Vézda, y además 60 especies nuevas.
(Aderkomyces gomezii Lücking, sp. nov. Type. Costa Rica. Cartago: Tapantí National Park, 2000 m, Jan 1992, Lücking 92-4249 (holotype, CR). ETYMOLOGY— Named after the Costa Rican botanist and ecologist Luis Diego Gómez.)
Palabras claves : Lichenes; Fungi; New species.
Biblioteca OET: NBINA-8961
Tolerance of soil pathogens co-varies with shade tolerance across species of tropical tree seedlings.
Resumen : A negative feedback between local abundance and natural enemies could contribute to maintaining tree species diversity by constraining population growth of common species. Soil pathogens could be an important mechanism of such noncompetitive distance and density-dependent (NCDD) mortality, but susceptibility to local pathogens may be ameliorated by a life history strategy that favors survivorship. In a shade-house experiment (1% full sun), we tested seedling life span, growth, and mass allocation responses to microbial extract filtered from conspecific-cultured soil in 21 tree species that varied in abundance and shade tolerance in a wet tropical forest (La Selva Biological Station, Costa Rica). Forty-three percent of the species had significant reductions, and 10% of the species had significant increases in life span, growth, root length, or root surface area when inoculated with microbial extract; 10% of the species experienced opposing reductions and increases in these characteristics. Contrary to expectation, species’ local abundance was not related to speciesspecific responses to microbial extracts from cultured soils. Across species, seedling shade tolerance (survival at 1% full sun) was negatively correlated with susceptibility to the microbial treatment for both survival and total mass accumulation, thereby exaggerating shade tolerance differences among species. Thus, soil pathogens may contribute to species coexistence through heightening niche differentiation rather than through negative density dependence in common species.
Palabras claves : Common Vs. Rare species; Density dependence; Janzen-Connell Hypothesis; Plant–soil feedback; Shade Tolerance; Soil pathogens; Species coexistence; Tropical forests.
Biblioteca OET: NBINA-8921
A review of the neotropical genus Eucalandra Faust, 1899 (Coleoptera; Curculionidae: Dryophthorinae)
(Es una publicación nueva para Estación Biológica La Selva)
Anderson, R. S. 2008. A review of the neotropical genus Eucalandra Faust, 1899 (Coleoptera; Curculionidae: Dryophthorinae). Zootaxa (1791): 57-67.
Resumen : The genus Eucalandra Faust is reviewed, including a redescription of the genus, diagnoses of the four previously described species, E. boxi
Palabras claves : Biodiversity; Weevils; New species ; Bamboo ; Taxonomy.
Biblioteca OET: NBINA-8799