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Subtropical Montane Forest (subtropical + montane_forest)
Selected AbstractsNest Selection by Cavity-nesting Birds in Subtropical Montane Forests of the Andes: Implications for Sustainable Forest ManagementBIOTROPICA, Issue 3 2009Natalia Politi ABSTRACT Development of sustainable forestry has been hampered in tropical countries by a scarcity of research on the ecological effects of logging. We focused on cavity-nesting birds, a group known to be sensitive to logging. Cavities used for nesting were not a random subset of all available suitable cavities. Birds selected cavities that were relatively high above the ground, had smaller entrances, and were excavated by woodpeckers. The use of tree species was also not random: Calycophyllum multiflorum, Blepharocalyx gigantea, and Podocarpus parlatorei were disproportionately important. Cavity nests were also more likely to be found in areas with trees with high mean diameter at breast height. This study emphasizes the need to maintain some unlogged forest patches within logging areas and retain certain species of trees. This study has implications for forest management in Argentina, where a new law mandates the sustainable use of forest resources and where many landowners are interested in forest certification. RESUMEN En los países tropicales la implementación del manejo forestal sostenible se ha visto limitado debido a la escasez de estudios sobre los efectos ecológicos de la explotación forestal. Nos focalizamos en aves que nidifican en huecos de árboles porque este es un grupo sensible a las prácticas de manejo forestal. Los huecos en árboles utilizados para nidificar no fueron un conjunto al azar de todos los huecos adecuados disponibles. Las aves seleccionaron huecos en árboles que estaban a una altura elevada desde el suelo, con entradas chicas y excavadas por carpinteros. El uso de las especies de árboles tampoco fue al azar: Calycophyllum multiflorum, Blepharocalyx gigantea y Podocarpus parlatorei fueron desproporcionadamente importantes. Fue más probable encontrar nidos en parches de árboles que tuvieron un promedio de diámetro a la altura del pecho más alto. Este estudio resalta la necesidad de retener algunos parches del bosque sin intervención dentro del área de manejo y retener ciertas especies arbóreas. Este estudio tiene implicancias en el manejo forestal en Argentina, donde una nueva ley plantea un uso sostenible de los recursos forestales y donde muchos propietarios están interesados en obtener una certificación forestal. [source] Landscape context and microenvironment influences on liana communities within treefall gapsJOURNAL OF VEGETATION SCIENCE, Issue 5 2008Agustina Malizia Abstract Questions: How do gap aspect, openness, age and gap density in the surroundings affect diversity and composition of lianas within treefall gaps? Are the variation patterns in liana communities within treefall gaps associated with their climbing mechanisms? Location: Subtropical montane forests in northwestern Argentina. Methods: We used ordination analyses (NMDS) and multiple regressions to describe liana communities (species and climbing groups, stems , 1 cm) in 35 gaps located in a 6-ha plot and to assess relationships with aspect, canopy and subcanopy openness, age and density of recent (three to eight years old) and old (> 8 years old) gaps. Results: Treefall gaps segregated in the ordination diagrams based on their liana species and climbing mechanisms composition: gaps surrounded by a higher density of recent gaps showed higher densities of lianas species using tendrils, spines/hooks and voluble stems. Liana density and richness (independent of stem density) were also positively associated with the density of recent gaps in the surroundings, and negatively associated to gap age. The number of liana species corrected per area was negatively associated to gap aspect and subcanopy openness, and absolute number of liana species was positively associated to gap canopy openness. Conclusions: This study integrates the analysis of different factors influencing liana communities within treefall gaps, and shows that spatial context of gap density (a variable largely neglected in previous studies) is particularly important on lianas composition and diversity, probably by increasing propagule input and the availability of small trellises for support. [source] Soil phosphorus and disturbance influence liana communities in a subtropical montane forestJOURNAL OF VEGETATION SCIENCE, Issue 3 2010Agustina Malizia Abstract Questions: What are the effects of soil, topography, treefall gaps, tree species composition, and tree density on liana species composition and total liana abundance? Location: A 6-ha permanent plot in a subtropical montane forest in northwest Argentina. Methods: Multiple regressions were used to quantify associations of liana species composition and total liana abundance with edaphic, disturbance and tree community variables. Gradients in liana and tree species composition were quantified using principal components analysis (PCA). Results: Liana species composition was correlated most strongly with soil phosphorus concentration (R2=0.55). Total liana aanased with phosphorus and the density of recent treefall gaps (R2=0.60). Conclusions: In our study area, liana composition and abundance are most strongly correlated with features of the physical environment, rather than host tree characteristics. Our results support the hypothesis that recent increases in liana abundance in mature tropical forests may be related to increased rates of gap formation. [source] Ancestry and divergence of subtropical montane forest isolates: molecular biogeography of the genus Abies (Pinaceae) in southern México and GuatemalaMOLECULAR ECOLOGY, Issue 10 2008JUAN P. JARAMILLO-CORREA Abstract The genus Abies has a complex history in southern México and Guatemala. In this region, four closely related species, Abies flinckii, A. guatemalensis, A. hickelii, and A. religiosa, are distributed in fragmented and isolated montane populations. Range-wide genetic variation was investigated across species using cytoplasmic DNA markers with contrasted inheritance. Variation at two maternally inherited mitochondrial DNA markers was low. All species shared two of the nine mitotypes detected, while the remaining seven mitochondrial DNA types were restricted to a few isolated stands. Mitochondrial genetic differentiation across taxa was high (GST = 0.933), it was not related to the taxonomic identity (amova; P > 0.05) of the populations, and it was not phylogeographically structured (GST , NST). In contrast, variation at three paternally inherited chloroplast DNA microsatellites was high. Chloroplast genetic differentiation was lower (GST = 0.402; RST = 0.547) than for mitochondrial DNA, but it was significantly related to taxonomy (amova; P < 0.001), and exhibited a significant phylogeographical structure (GST < RST). Different analyses of population structure indicated that A. flinckii was the most divergent taxon, while the remaining three species formed a relatively homogeneous group. However, a small number of the populations of these three taxa, all located at the limits of their respective ranges or in the Transverse Volcanic Belt, diverged from this main cluster. These trends suggest that the Mesoamerican Abies share a recent common ancestor and that their divergence and speciation is mainly driven by genetic drift and isolation during the warm interglacial periods. [source] | ||||||||||