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Papers by Aranzazu Guevara

Plant and Soil, Dec 17, 2014

Trees-structure and Function, Aug 8, 2022

Ecología austral, Apr 1, 2011

Plant Ecology, 2018

Fine root growth in natural vegetation is difficult to predict due to its regulation by soil and ... more Fine root growth in natural vegetation is difficult to predict due to its regulation by soil and plant factors. Field studies in arid ecosystems show a variety of root responses to soil resources and to plant aboveground phenology that sometimes differ from root responses predicted by controlled experiments. There is a pressing need to cover a greater diversity of plant species and ecological scenarios in field studies. In this paper, we have studied fine roots of Prosopis flexuosa trees living with or without access to phreatic water in an inter-dune valley and a dune flank, respectively, in the Central Monte Desert, Argentina. We have described fine root growth over time and at different depths by rhizotron observations and soil core auger samples in relation to soil water and nutrients, tree crown phenology, plant water and nutrient status. We have found that surface soil moisture from rainfall is the variable that best predicts seasonal topsoil fine root growth. Access to groundwater advanced leaf sprouting with respect to rainfall, but did not advance root growth that stayed linked to rainfall in valley and dune flank trees. Trees without access to phreatic water produced deeper and thicker or denser roots, which is consistent with the poor soil resource content of dunes. Variations in rainfall dynamics due to global climate change may have a Communicated by Zoltan Nagy.

Environmental and Experimental Botany, 2019

This is a PDF file of an unedited manuscript that has been accepted for publication. As a service... more This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Blue light attenuation mediates morphological and architectural acclimation of Vitis vinifera cv. Malbec to shade and increases light capture

Journal of Geophysical Research, 2011

Journal of Arid Environments, 2014

The high productivity of sandy groundwater-coupled woodlands in the Monte Desert is exploited by ... more The high productivity of sandy groundwater-coupled woodlands in the Monte Desert is exploited by local pastoralist communities for fuel, domestic use, and manure accumulation and export to irrigated oases. We explored processes and species that could replenish C and N losses from the ecosystem using stable isotopes of plants and nutrient analysis of soils. Foliar 15 N natural abundances, which were lower in Prosopis flexuosa plants and C4 grasses from dune flanks, indicate that these plants may fix atmospheric N 2. Groundwater availability did not decrease water use efficiency (indicated by similar foliar d 13 C in dune flanks and interdune valleys), suggesting that the higher stomatal conductance allowed by the additional water source and reported in previous studies is coupled with higher photosynthetic rates, increasing productivity in interdune valleys. Water use efficiency and N stable isotopes of P. flexuosa responded to temporal changes in precipitations, suggesting rapid shifts of N sources, to uptake of recently mineralized soil N (higher d 15 N and lower d 13 C after rain events). Soil heterogeneity was low, except for ammonium and moisture in interdune valley soils. This study allows us to hypothesize that carbon is replenished in interdune valleys by increasing photosynthetic rates, and N is replenished by N 2 fixation done by young P. flexuosa plants and grasses from dune flanks.

Ecología Austral

R��. En el marco de la Agenda 2030 para el cumplimiento de los Objetivos de Desarrollo Sosten... more R��. En el marco de la Agenda 2030 para el cumplimiento de los Objetivos de Desarrollo Sostenible (ODS), el ODS 15 promueve la "Vida en la tierra", y la Meta 15.3, lograr la neutralidad en la degradación de la tierra (NDT). Este trabajo se centra en la región del Chaco Salteño y en el sitio piloto Chaco Semiárido de la provincia de Salta, Argentina (SPChS). Los objetivos son 1) evaluar el estado de la NDT en la región del Chaco Salteño y en el SPChS entre 2001 y 2018, y 2) determinar las variables estructurales de la vegetación y propiedades físico-químicas del suelo a escala local que puedan usarse para complementar la evaluación de la NDT. Para evaluar el estado de la NDT se calcularon indicadores de cambios en la cobertura del suelo y en la productividad primaria neta aérea (PPNA) en base a mapas de cobertura del Proyecto MapBiomas Chaco-Colección 2.0 y de los productos quincenales de MODIS (MOD 13Q1, anual). Para explorar la relación entre PPNA con las variables de vegetación y suelo se realizó un análisis de correlación. Encontramos que 14.3% de la región del Chaco Salteño experimentó cambios negativos de cobertura y 20.8% de pérdidas en la PPNA asociados principalmente a la transición de áreas con bosque nativo a cultivos. En tanto, en el SPChS, estos cambios representan una baja extensión de la superficie. La PPNA correlacionó significativa y positivamente, en particular, con la cobertura vegetal, la materia orgánica y la estabilidad de agregados, por lo que estas variables podrían usarse como indicadores complementarios para evaluar la NDT a escala local. Finalmente, los resultados presentados constituyen un primer marco de referencia para articular prioridades en la planificación de intervenciones de la NDT en la región del Chaco Salteño, y en particular en el SPChS. [Palabras clave: tierras secas, Chaco Salteño, degradación de tierras, cobertura del suelo, productividad primaria neta aérea] A��. State of neutrality in land degradation in the Chaco Salteño between 2001 and 2018. Within the framework of the 2030 Agenda for the fulfillment of the Sustainable Development Goals (SDGs), SDG 15 promotes "Life on land", and Target 15.3 focuses on achieving land degradation neutrality (LDN). This work is focused on the Chaco Salteño region and the semi-arid Chaco pilot site in the province of Salta, Argentina (SPChS). The objectives are 1) to assess the state of LDN in the Chaco Salteño region and in the SPChS between 2001 and 2018, and 2) to determine the structural variables of the vegetation and physical-chemical properties of the soil at a local scale that can be used to complement the LDN evaluation. To evaluate the status of LDN, the indicators of changes in land cover and in aboveground net primary productivity (ANPP) were calculated, based on the coverage maps of the MapBiomas Chaco Project-Collection 2.0 and MODIS biweekly products (MOD 13Q1, annual). To explore the relationship between ANPP with the vegetation and soil variables, a correlation analysis was performed. We found that 14.3% of the Chaco Salteño region experienced negative changes in coverage and 20.8% losses in ANPP associated mainly with the transition from areas with native forests to crops. Meanwhile, in the SPChS, these changes represent a low extension of the surface. The ANPP correlated significantly and positively, in particular, with vegetation cover, organic ma�er and aggregate stability, so these variables could be used as complementary indicators in the evaluation of LDN at a local scale. Finally, the results of this research constitute a first frame of reference to articulate priorities in the planning of LDN interventions in the Chaco Salteño region, and particularly in the SPChS.