Woody plant regeneration in the semiarid Chaco forest: relationship with biotic and abiotic factors in microsites created by logging

La cosecha forestal genera micrositios que pueden ser colonizados por distintas especies de plantas leñosas, donde factores bióticos y abióticos pueden influir en la regeneración. En este trabajo se describen tres micrositios creados por la tala (caminos principales, vías de saca y claros de extracción) en dos sitios con distinto tiempo de recuperación (uno y dos años) del Chaco semiárido, Argentina. Se compara la riqueza y diversidad de plantas leñosas y se evalúa la relación de la densidad de plantas en función del tipo de micrositio, tiempo de recuperación, dureza del suelo, cobertura del dosel y cobertura de herbáceas. En los tres micrositios, la composición y riqueza de especies fueron similares, dominados por las mismas especies. Los caminos tuvieron suelos más compactados, las vías de saca doseles más cerrados y los claros suelos con mayor cobertura herbácea. La densidad de leñosas dependió de la interacción de las co-variables (dureza del suelo, coberturas del dosel y de herbáceas) con los micrositios y el tiempo de recuperación. La densidad en los caminos fue baja y se relacionó negativamente con la dureza del suelo y positivamente con las coberturas del dosel y de herbáceas, sugiriendo una interacción positiva en los micrositios más afectados. La regeneración de las dos especies de mayor valor forestal fue baja en comparación a otras especies; Aspidosperma quebracho-blanco tuvo densidad similar y Schinopsis lorentzii mayor en comparación a la regeneración de la matriz circundante. Sin embargo, este resultado debe interpretarse con cuidado debido a la baja constancia de ambas especies (proporción de parcelas con un cierto taxón). Se propone, con cautela, que los micrositios generados no estarían afectando negativamente a la regeneración de las dos especies de mayor valor forestal de este ambiente.Logging activities generate microsites that can be colonized by different woody plant species whose regeneration may be influenced by biotic and abiotic factors. This work describes three microsites created by logging (main roads, skid trails and logging gaps) in two sites with different recovery time (one and two years) in the semi-arid Chaco of Argentina. Woody plant richness and diversity are compared and the relationship of plant density as a function of microsite type, recovery time, soil compaction, canopy cover and herbaceous cover is evaluated. Richness and species composition were similar in all microsites, which were dominated by the same species. Main roads presented more compacted soil, skid trails had denser canopies and logging gaps had soils with larger herbaceous cover. Woody plant density depended on the interaction of the covariates (soil compaction, canopy cover and herbaceous cover) with microsites and recovery time. Road plant density was low and was negatively related with soil compaction and positively related with canopy cover as well as with herbaceous cover, suggesting a positive interaction (facilitation) in microsites that were most affected by logging. The regeneration of the two most valuable timber species was low compared to other species. In the microsites studied, Aspidosperma quebracho-blanco had a similar density and Schinopsis lorentzii a higher density compared to the regeneration found in the surrounding matrix reported in other studies, but this result should be interpreted with caution due to the low constancy (proportion of plot containing a certain taxon). We propose, cautiously, that generated microsites would not be negatively affecting the regeneration of the two most valuable timber species in this environment.Fil: Tálamo, Andrés. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Salta. Instituto de Bio y Geociencias del Noroeste Argentino; ArgentinaFil: Lopez de Casenave, Javier Nestor. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución; ArgentinaFil: Núñez Regueiro, Mauricio Manuel. University of Florida. Wildlife Ecology and Conservation Department; Estados Unidos de América; . Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Caziani, Sandra Monica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Salta. Instituto de Bio y Geociencias del Noroeste Argentino; Argentin

Variation in woody vegetation among sites with different disturbance histories in the Argentine Chaco

We studied the composition and structure of the woody plant community in a logged/grazed forest, an abandoned road, a burned forest, and a primary forest as a control. The disturbances occurred 10 years prior to the study. The logged/grazed forest was similar in physiognomy to the primary forest, whereas shrubs dominated the abandoned road and burned forest. Using rarefaction techniques, the total species richness (adult, >0.5 cm diameter, and saplings, <0.5 cm diameter) was significantly highest in the logged forest. Basal area and adult plant density were similar in the logged and primary forest, and considerably higher than those of the burned forest and abandoned road, the last two types having more stems per individual. Species composition differed among communities; most notably some pioneer species were absent from the primary forest. For saplings, the abandoned road had the lowest species richness and plant density. Sapling density was highest in the logged forest due to one shrub species that was abundant in disturbed areas. Saplings of one valuable timber species, Aspidosperma quebracho-blanco, were abundant on all sites, probably due to the capacity of this species to sprout after root damage. Stem densities in the primary and logged forests were higher than on the abandoned road and in the burned forest except for the smallest diameter class (0.5-1 cm). Logged forest tended to have higher densities, but smaller individuals than the primary forest. Considering the paucity of well-conserved areas in the Argentine Chaco, the management of extended accidental disturbance (i.e. forest fires) should be considered for long-term use and conservation planning.Fil: Tálamo, Andrés. Universidad Nacional de Salta. Facultad de Ciencias Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta; ArgentinaFil: Caziani, Sandra Monica. Universidad Nacional de Salta. Facultad de Ciencias Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta; Argentin

Woody vegetation of an abandoned road in the semiarid Chaco forest in relation to the surrounding vegetation matrix and grazing

En un camino abandonado del bosque chaqueño semiárido (Parque Nacional Copo, Argentina), comparamos la comunidad de plantas leñosas en dos sectores: uno de bosque secundario con presencia de ganado vacuno (“Vacas-Bs”), y otro de bosque primario sin presencia de ganado vacuno (“Sin Vacas-Bp”). Para esto, medimos atributos de la vegetación leñosa en parcelas dispuestas al azar en cada sector. La riqueza de especies, la densidad de plantas adultas y el área basal fueron similares en los dos sectores. En las parcelas del sector “Vacas-Bs”, Capparis retusa representó el 34% del área basal total, disminuyendo la equitatividad del ensamble de este sector. El número de ramas por individuo y la densidad de ramas fueron similares en ambos sectores. Achatocarpus praecox, Prosopis sp. y Ximenia americana estuvieron presentes sólo en las parcelas del sector “Vacas-Bs”, mientras que Senna aphylla fue encontrada sólo en las parcelas del sector “Sin Vacas-Bp”, aunque estas diferencias podrían deberse a la variación intrínseca. En el tiempo considerado, no encontramos evidencias marcadas de que la comunidad de plantas leñosas difiera entre sectores con distinta historia de pastoreo y vegetación circundante.In an abandoned road in of the semiarid Chaco forest (Copo National Park, Argentina), we compared the community of woody plant species in two areas: one with livestock, surrounded by secondary forest, and another without livestock, surrounded by primary forest. We measured characteristics of the woody vegetation in nine plots (2 x 100 m) selected randomly in the area with livestock and in six plots in the area without livestock. Considering the same number of samples, species richness was similar in both areas. No significant differences were found in species richness per plot, adult plants density and basal area between the two areas. In the plots with livestock, 34% of the total basal area corresponded to Capparis retusa, decreasing the assembly eveness in this area. The number of branches per individual and the branch density were similar in both areas. Achatocarpus praecox, Prosopis sp. and Ximenia americana were present only in plots with livestock, while Senna aphilla was found only in the plots without livestock, however these differences could be the result of intrinsic variations. The density and basal area per species were not different between areas. In the considered period of time, we did not find evidence of differences in the community of woody plant species related to the different grazing history and the surrounded vegetation matrix.Fil: Tálamo, Andrés. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Bio y Geociencias del NOA. Universidad Nacional de Salta. Facultad de Ciencias Naturales. Museo de Ciencias Naturales. Instituto de Bio y Geociencias del NOA; ArgentinaFil: Trucco Aleman, Carlos Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Bio y Geociencias del NOA. Universidad Nacional de Salta. Facultad de Ciencias Naturales. Museo de Ciencias Naturales. Instituto de Bio y Geociencias del NOA; Argentina. Ministerio de Ambiente y Desarrollo Sustentable de la Provincia de Salta; ArgentinaFil: Caziani, Sandra Monica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Bio y Geociencias del NOA. Universidad Nacional de Salta. Facultad de Ciencias Naturales. Museo de Ciencias Naturales. Instituto de Bio y Geociencias del NOA; Argentin

Components of woody plant diversity in semi-arid Chaco forests with heterogeneous land use and disturbance histories

We assessed components of woody plant diversity within and between 16 sites dispersed across the nearly 200,000 ha of the Semi-arid Chaco vegetation of the Copo Conservation Unit, northern Argentina. Argentina's Semi-arid Chaco is an object of international conservation concern, as it is under pressure from conversion to agroindustry supplanting long-standing practices of logging and livestock grazing. We recorded from 16 (shrubby grassland following forest fire) to 27 (selectively logged forest) woody plant species per site and 37 species in total (gamma diversity). Additive partitioning showed that alpha diversity contributed 59% to gamma diversity and beta diversity only 41%. A separate additive partitioning of gamma diversity of the 13 forested sites alone showed that beta diversity attributable to logging history was considerably lower than remaining beta diversity and alpha diversity. Ordination analyses confirmed this finding: species composition of unlogged, selectively logged and intensively logged forest sites was quite similar. Results suggest that (1) woody vegetation, at least, of the Semi-arid Chaco is quite tolerant to traditional modes of land use and that (2) conservation of this vegetation as a whole must include not only "pristine" sites varying in edaphic conditions but also sites varying in land use and management histories. © 2012 Elsevier Ltd.Fil: Tálamo, Andrés. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Bio y Geociencias del NOA. Universidad Nacional de Salta. Facultad de Ciencias Naturales. Museo de Ciencias Naturales. Instituto de Bio y Geociencias del NOA; ArgentinaFil: Lopez de Casenave, Javier Nestor. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; ArgentinaFil: Caziani, Sandra Monica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Bio y Geociencias del NOA. Universidad Nacional de Salta. Facultad de Ciencias Naturales. Museo de Ciencias Naturales. Instituto de Bio y Geociencias del NOA; Argentin

Waterbird richness in altiplano wetlands of northwestern Argentina

We measured waterbird richness and abundance, and characterized wetland features (altitude, size, and presence of submergent vegetation) of 50 altiplano wetlands, during summer and winter, 1998. We estimated 36,700 individuals of 24 avian species during the summer census. James' Flamingo (Phoenicoparrus jamesi) and Andean Flamingo (P. andinus) were the most abundant species, followed by Horned Coot (Fulica cornuta), Chilean Flamingo (Phoenicopterus chilensis), and Crested Duck (Anas specularioides). These species comprised 78% of total individuals. In winter, we counted 7,421 individuals of 16 species, and the three flamingo species were the most abundant. In summer, we found Chilean and Andean Flamingos primarily in intermediate-altitude wetlands (3,500-4,000 m a.s.1.), whereas James' Flamingos and other waterbirds were above 4,000 m. In winter, the three flamingo species moved to lower-altitude wetlands (below 3,500 m). Waterbird abundance was positively correlated with wetland size in wetlands with aquatic vegetation, with waterbird richness in wetlands without macrophytes. During summer, total abundance and richness were significantly higher in wetlands with macrophytes, where Chilean Flamingo and ten other waterbird species (e.g., ducks, grebes, gulls, and coots) were more common. James' Flamingo was the only species more abundant in hypersaline wetlands. In summer, four wetlands (Grande, La Alumbrera, Vilama, and Pozuelos) contained 68% of the total individuals, with more than 3,000 waterbirds each. In winter, wetlands Pozuelos and Guayatayoc included 50% of waterbirds counted, with more than 5,000 birds each. Thirty four percent of the wetlands surveyed are within protected areas, but only in Laguna de los Pozuelos Natural Monument is it actually implemented. In 42% of the wetlands we detected land uses that could represent threats to these environments. Here we propose some criteria to detect and prioritize relevant sites for conservation of altiplano waterbirds: a) large aggregations of individuals, either seasonal or permanent, b) vulnerable and/or endemic species and presence of nesting sites, c) ecological uniqueness, d) proximity to other complementary wetlands, e) high heterogeneity between and within sites. The complementary use of these environments by waterbirds, both seasonally and spatially, suggests considering conservation action from a landscape perspective.Fil: Caziani, Sandra Monica. Universidad Nacional de Salta; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta; ArgentinaFil: Derlindati, Enrique Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta; ArgentinaFil: Tálamo, Andrés. Universidad Nacional de Salta; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta; ArgentinaFil: Sureda, Ana L.. Universidad Nacional de Salta; ArgentinaFil: Trucco Aleman, Carlos Eduardo. Universidad Nacional de Salta; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta; ArgentinaFil: Nicolossi, Guillermo. Administración de Parques Nacionales; Argentin