Enrique H Bucher | Universidad Nacional de Córdoba (original) (raw)

Papers by Enrique H Bucher

Journal of Arid Environments, Mar 1, 2009

Revista Chilena de Historia Natural, 1987

Applied Soil Ecology, May 1, 1999

We identi®ed and measured changes in soil characteristics, nutrient availability and microbial ac... more We identi®ed and measured changes in soil characteristics, nutrient availability and microbial activity to a gradient of grazing intensity in the Chaco region of northwestern Argentina (248 43 H S and 638 17 H W). Three sites were selected for comparison: 1. highly restored (no grazing for 20 years); 2. moderately restored (eight years of restoration); and 3. highly degraded (a typical Chaco campesino dwelling, extremely overgrazed). On each site two sets of soil and litter samples were taken during the dry and wet season, respectively. The following parameters decreased as grazing intensity increased: soil moisture (from 4.5% to 2.25%), organic matter (from 4.68% to 1.45%), and nitrogen content (from 0.28% to 0.14%). Salt content increased from 1.8 to 5.0 d sm À1. Microbial activity ranged from 0.89 mg CO 2 g À1 7 day À1 at the restored sites to 0.22 mg CO 2 g À1 7 day À1 at the highly degraded site. The seasonal variations in density and activity of microorganisms increased from the highly restored to the highly degraded site, probably as a response to an increased lack of humidity. The cellulolytic and nitri®er groups were the most affected, whereas the ammoni®er and free-living nitrogen-®xing organisms decreased in the highly degraded site only. Nitrogen ®xation was more intense at the moderately restored site followed by the highly degraded site. The observed values are interpreted as resulting from the interaction between organic matter availability (as energy source) and nitrogen de®ciency. Our results suggest a strong in¯uence of overgrazing on the soil fertility, as well as on the soil ability to buffer water stress during the dry season. When compared with other savannas of the world, soils at the restored sites show high soil nutrient and organic matter levels, probably as a result of high phosphorous availability resulting from their recent geological origin.

Ecological studies, 1982

From north-eastern Brazil to central-north Argentina there is a corridor of open vegetation forma... more From north-eastern Brazil to central-north Argentina there is a corridor of open vegetation formations called “the diagonal of open formations” by Vanzolini (1974). Two dry woodland areas, the “caatinga” in north-eastern Brazil and the “chaco” in northern Argentina, are isolated by a savanna corridor, sandwiched between the coastal and Amazonian rain forests, known as “cerrado” or “campos cerrados”. Through the chaco this diagonal of open formations affords access and transconnection of xeric areas from the west, north-west and south (Monte Desert, Andean shrub formations and Patagonian Desert, Figure 1).

The diversity of amphibian and reptile species of the Mar Chiquita wetland is presented in this c... more The diversity of amphibian and reptile species of the Mar Chiquita wetland is presented in this chapter, including 16 amphibians, 18 snakes, 14 lizards, 3 amphisbenids, and 2 turtles. Each of them is briefly described, including their main characteristics and habitat preferences. Given the great environmental heterogeneity characteristic of Mar Chiquita, the distribution of the amphibian and reptile species is not homogeneous. At least two broad types of environments can be distinguished: the Chaco dry forest of the peripheral area around the Mar Chiquita depression and the Dulce River wetland.

Bird Behavior, Jul 1, 1990

MARTELLA, MB and EH BUCHER 1990. Vocalizations of the Monk Parakeet. Bird Behaviour 8: 101-110. V... more MARTELLA, MB and EH BUCHER 1990. Vocalizations of the Monk Parakeet. Bird Behaviour 8: 101-110. Vocalizations and associated behaviour of the Monk Parakeet Myiopsitta monachus were recorded in the field during the breeding (summer) and non-breeding (winter) ...

Trends in Ecology and Evolution, Sep 1, 1986

Applied Soil Ecology, Mar 1, 2001

Very little is known about the effect of overgrazing on carbon loss from soil in semi-arid savann... more Very little is known about the effect of overgrazing on carbon loss from soil in semi-arid savannas and woodlands of South America. Soil carbon parameters were measured in a 10,000 ha restoration project in the western Chaco of Argentina (24° 43′ S and 63° 17′ ...

The Dulce River wetland, located in the lower floodplain of the Dulce River, is considered one of... more The Dulce River wetland, located in the lower floodplain of the Dulce River, is considered one of the few large wetlands remaining in the Chaco ecoregion. This wetland is characterized by a heterogeneous and complex landscape that combines the Dulce River braided channel, temporary and permanent ponds, extended grasslands, halophytic scrubs, and elevated areas with woody vegetation, all of which provide habitat to abundant and diverse flora and fauna. The vegetation formations are described in relation to the dynamics generated by the annual flood and fire pulses, which are critical drivers of the wetland dynamics. With regard to land use, the wetland remained almost unaltered and sparsely populated until recent years. However, at present, the wetland is threatened by a reduction in water flow and increasing control of the annual flooding pulse due to water diversion for irrigation and urban consumption in the upper Dulce River. In addition, a rapid change in land use from transhumant pastoralism to a sedentary, highly technified beef and crop production is taking place. As a result, replacement of original vegetation with introduced pastures and crops is generating negative environmental impacts and social conflicts, being of particular concern in the protected area.

Ecological Economics, Oct 1, 1995

The proposed Paraguay-Paran~ waterway project, know as "Hidrovia", would improve and develop year... more The proposed Paraguay-Paran~ waterway project, know as "Hidrovia", would improve and develop year-round navigation by large ships and barge trains from Cficeres, Brazil, to the harbor of Nucva Palmira, Uruguay. Of particular environmental concern, the project would drastically alter the river system in the previously undeveloped reach from Cficeres to Corumbfi, Brazil, and directly affect the Pantanal. The Pantanal is one of the world's largest wetlands and is important both for the biodiversity it supports and for its regulatory impact on the downstream river system. This preliminary evaluation of the project establishes a critical value for the environmental costs that, if included in the evaluation of the project, would tip the scale in favor of preserving the Pantanal rather than developing the waterway through it. It is concluded that the environmental costs may exceed this critical value and that the waterway may be uneconomical in the Pantanal. The indication is that expenditures on further feasibility studies are likely best spent by investigating the feasibility of the project downstream from the Pantanal.

The water balance of the Mar Chiquita closed basin is described in term of interactions between r... more The water balance of the Mar Chiquita closed basin is described in term of interactions between rainfall, evaporation, and topography. This interplay of factors has shown two dramatically differing periods in Mar Chiquita, given that in the 1970s, the regional climate changed drastically, with a substantial rainfall increase that tripled the lake size for the first time in its whole geological history since the Middle Pleistocene. The hydrological characteristics of the whole basin, tributary rivers, and the Mar Chiquita Lake are described based on the available information, which includes historical accounts and instrumental records since the 1960s. In addition, existing modeling studies of the Mar Chiquita Lake system are described, and their results are evaluated in terms of future research needs, particularly under climate change scenarios.

This chapter presents a summary of the current conservation status of Mar Chiquita Lake and Dulce... more This chapter presents a summary of the current conservation status of Mar Chiquita Lake and Dulce River wetland, including three main sections. Firstly, a brief description of the values that support the conservation of this wetland and the legislation that provides its protected area condition are provided. Secondly, the environmental threats affecting the region are analyzed. It is concluded that water diversion and alteration of the hydrological regime, habitat alteration, changes in land use, and pollution are considered the main threats to the wetland that require priority consideration. Finally, the management difficulties and administration constraints related to the large size of the wetland are analyzed.

Acta Ornithologica, Feb 13, 2020

Abstract. Food resource availability regulates population levels and reproductive success in seve... more Abstract. Food resource availability regulates population levels and reproductive success in several parrot species. Of the 59 threatened parrot species in the Neotropics, information on diet is available for only 34. Unsustainable forest management can eliminate trees with seeds and fruits that are key food resources for parrots. Tucuman Amazon Amazona tucumana is an endemic and threatened parrot species categorized as Vulnerable that occurs only in Andean montane forests of northwestern Argentina and southern Bolivia; i.e., the Southern Yungas. The diet of Tucuman Amazon, food availability, specialization, key food resources, and seasonal and spatial variation of food resources were determined. Feeding bouts of Tucuman Amazon were recorded from December 2007 to February 2009 in El Rey National Park. Availability of trees with seeds, fruits or flowers that could be used by Tucuman Amazon as food resources was assessed in phenology plots in cloud forest (high elevation humid forest) and transition forest (semideciduous forest located in the piedmont). Both forest types showed marked seasonality in availability of food resources for Tucuman Amazon. Sixty-six percent of this species feeding bouts were on seeds. Podocarpus parlatorei is the most widely used tree species by Tucuman Amazon in the cloud forest during the reproductive period and Acacia visco in the transition forest in the non-reproductive period. Podocarpus parlatorei could be critical for the development of Tucuman Amazon chicks, due to the high fat and oil content of its seeds and fruits. Tucuman Amazon used fewer food tree species during the non-reproductive than the reproductive period, showing a greater specialization of food resources (i.e., narrower niche breadth). To ensure the production of fruits of P. parlatorei and A. visco, sustainable forest management in the Southern Yungas should retain an adequate level of these key resources for Tucuman Amazon.

Bird Conservation International, Jan 4, 2012

Tucuman Parrot Amazona tucumana breeds in the cloud-forest of southeastern Bolivia and northweste... more Tucuman Parrot Amazona tucumana breeds in the cloud-forest of southeastern Bolivia and northwestern Argentina (or Southern Yungas forest). We studied the nesting requirements of the Tucuman Parrot and assessed cavity availability, reuse, and spatial pattern of nests in El Rey National Parkone of the last mature, undisturbed areas of the Southern Yungas forest. We recorded 44 nesting attempts in seven tree species, with most nests (95%) being located in live canopy trees. 60 cm DBH. Most parrot nest-cavities occurred in Blepharocalix salicifolius (60%) and cavities in this species were selected significantly more than expected based on availability. Nests were shallower and higher than nests of other Amazona species. For all years combined, mean nest density of Tucuman Parrot was 0.24 6 0.04 nest ha-1 and the distance to the nearest active nest was significantly greater than the distance between all trees used as nests. Nesting pairs of Tucuman Parrot were separated by 144.1 6 152.8 m, while potential nest-trees were 66.0 6 55.4 m apart. Density of suitable cavities for nesting was 4.6 cavities ha-1. Approximately 16 suitable cavities were available for each breeding pair (0.24 breeding pair ha-1 and four suitable cavities ha-1) and 5% of the suitable cavities available were occupied, suggesting that suitable cavities are not a limiting resource. However, due to the territorial behaviour of breeding pairs, some of these cavities are unavailable to other breeding pairs. The spatial requirements of Tucuman Parrot for nesting could limit management actions intended to increase the density of nesting pairs. because they depend on other species (e.g. woodpeckers) or factors (e.g. wood decay) for the generation of cavities (Land et al. 1989) and require large old trees and snags for nesting (Mawson and Long 1994). The scarcity of suitable cavities for nesting in forest under timber exploitation led to a sharp decline of populations of Thick-billed Parrot Rhynchopsitta pachyrrhyncha in Mexico (Lanning and Shiflett 1983, Monterrubio-Rico and Enkerlin Hoefflich 2004). Most studies have determined the requirements of parrot species for nesting: cavity entrance width, internal diameter, depth, height above ground, orientation of openings, and tree diameter at breast height (DBH), and condition (

Colonial waterbirds, 1992

Applied Soil Ecology, Jun 1, 2001

... Soc. Am. J. 59, pp. 831837. Full Text via CrossRef | View Record in Scopus | Cited By in Sco... more ... Soc. Am. J. 59, pp. 831837. Full Text via CrossRef | View Record in Scopus | Cited By in Scopus (31). Jarsum, B., Gorgas, J., Bosnero, H., Zamora, E., Lovera, E., 1990. Provincia de Córdoba. In: Atlas de Suelos de la República Argentina. INTA, Buenos Aires, pp. 393512. ...

Journal of Arid Environments, Dec 1, 2006

ABSTRACT Seed passage through the gut of vertebrates is critical for endozoochorus seed dispersal... more ABSTRACT Seed passage through the gut of vertebrates is critical for endozoochorus seed dispersal because it may influence seed viability and germination capacity. Foxes are important fruit-eaters and presumed seed dispersers in the Chaco ecoregion. We experimentally assessed the seed passage time (SPT) and its effect on seed viability and germination in two fox species (Pseudalopex gymnocercus and Cerdocyon thous) that occur in the Chaco. Passage time was measured using both artificial seeds of three sizes and wild seeds of four native fleshy-fruit species commonly consumed by foxes (Ziziphus mistol, Acacia aroma, Celtis tala, and Syagrus romanzoffiana). The average SPT was 6.8 h for the Pampa fox and 7.7 h for the crab-eating fox. Passage time did not differ either among seeds of different sizes or between fox species. Passage through digestive tract of both fox species did not affect seed survival, whereas germination rate was slightly improved. Our data suggest that both fox species are legitimate seed dispersers of the four species studied, having a positive effect on both germination rate and dispersal distance from the parent plant.