The community of Furcraea parmentieri, a threatened specie, Central Mexico

The flora and vegetation of Furcraea parmentieri (Roezl ex Ortigies) Garcia-Mend. (F bedinghausii) community was studied on the Pelado volcano, at the S area of Mexico City. Following Zurich-Montpellier criteria, 25 phytosociological plots were done, and the Jaccard index of similarity was calculated. Furcraea parmentieri is associated with Muhlenbergia macroura to form an azonal community between 3 020 and 3 300 m, on rocky soils and gaps of Pinus-Alnus forest. Three subcommunities can be distinguished: Furcraea parmentieri-Trisetum virletii, Furcraea parmentieri-Aegopogon cenchroides and Furcraea parmentieri-Solanum cervantesii. 87 species were recorded, representing 63 genera and 27 families, of which the most abundant were Asteraceae and Poaceae. The proper environmental conditions for Furcraea parmentieri are: altitudes between 3 020 and 3 100 m, N exposures, acid soils with pH 6.0 and slopes among 36° and 45°. The main problem for species preservation in the area is repeated burning, that depletes soils and destroys vegetative bulbils, causing population diminishment. Conservation of Furcraea parmentieri community is important because, it is an endangered and endemic species, as well as a soil-stabilizing species for severely degraded zones (NOM-059-ECOL-2001).Se estudió la flora y vegetación de la comunidad de Furcraea parmentieri (Roezl ex Ortigies) Garcia-Mend. (F. bedinghausii) especie amenazada y endémica de México (NOM-059-ECOL-2001), en el volcán Pelado, al S de la Ciudad de México. Se realizaron 25 levantamientos siguiendo la escuela fitosociológica Zurich-Montpellier, a los que se calculó el índice de similitud de Jaccard. Furcraea parmentieri se asocia con Muhlenbergia macroura formando una comunidad azonal, entre los 3 020 y 3 330 m, sobre suelos rocosos y claros del bosque de Pinus-Alnus. Se diferenciaron tres subcomunidades: Furcraea parmentieri-Trisetum virletii, Furcraea parmentieri-Aegopogon cenchroides y Furcraea parmentieri-Solanum cervantesiis. Se registraron en total 87 especies agrupadas en 63 géneros y 27 familias, siendo las más abundantes Asteraceae y Poaceae. Las condiciones ambientales propicias para el establecimiento de Furcraea parmentieri son altitudes entre 3 020 a 3 100 m, en exposición N, suelos ácidos con pH 6.0 y pendientes de 36° a 45°. El mayor problema para la conservación de la especie en el área son las quemas repetidas que empobrecen el suelo y destruyen los bulbilos, causando la disminución de las poblaciones. La conservación de F. parmentieri es importante porque además de ser una especie amenazada y endémica, estabiliza suelos en zonas severamente degradadas

Insights into hydrogen generation from formic acid using ruthenium complexes

The decomposition of a HCO2H/Et3N azeotrope to a mixture of hydrogen and carbon dioxide may be catalyzed by a number of Ru(III) and Ru(II) complexes with high efficiency at ca. 120 degrees C. Evidence that suggests that the precatalyst may in each case be a common ruthenium dimer has been obtained through H-1 NMR and X-ray crystallographic studies of the complexes formed in situ and of analysis of the gases generated in the reaction using FTIR and gas chromatography methods