Why Are Moss Biocrusts Necessary for System Conservation in a Semiarid Region of Southern Argentina?

The importance of biological crusts in arid and semiarid ecosystems has been widely recognized in the last decades, but their function is still not fully known, much less so in our country (Argentina) and region, where they have often gone unnoticed. Biological crusts appear in sites with a low level of disturbance and have a fundamental role in maintaining the soil surface structure. In the Monte ecoregion of Rio Negro province, Argentina, this layer is dominated by moss, and it is present in diverse physiognomic-floristic types of vegetation, but it tends to disappear in sites disturbed by grazing and by severe fires, and at sites where clearing methods were used to remove the soil surface. The multiple benefits that these crusts can provide to ecosystems justify the need to intensify the knowledge of their structure and functioning, to understand the particular role that they fulfill and to be able to manage these systems by taking this component into account

Aspectos ecofisiológicos de dos forrajeras estivales de los pastizales de la Depresión del Salado (Paspalum dilatatum Poir. y Bothriochloa laguroides D. C.)

p.57-74Dos forrajeras nativas de los pastizales de la Depresión del Salado fueron sometidas a campo y en invernáculo a distintos tratamientos de defoliación y sombreado. Se analizó el efecto de los tratamientos sobre la aparición, floración y muerte de macollos, nivel de reservas y crecimiento radical. En las plantas del ensayo a campo se observó un aumento en el ritmo de macollaje como consecuencia de la defoliación. Los niveles de reservas y la aparición de raíces por planta no fueron afectados por los tratamientos. Diferente fue el resultado de las plantas tratadas en el invernáculo donde se observó un efecto detrimental de la defoliación sobre la aparición de macollos y biomasa radical. El ensayo a campo permitió tener una visión más integral de la respuesta de las plantas al medio analizándose diversas hipótesis

The influence of Larrea divaricata on soil moisture and on water status and growth of Stipa tenuis in southern Argentina

We studied the effect of a dominant shrub (Larrea divaricata) on soil moisture, and how this affected water potential and growth of a dominant grass (Stipa tenuis) in a shrubland located in southern Argentina. Soil moisture in the upper 10 cm of the soil was lower ( po0?05) or similar (po0?05) under the shrub canopy than in the open intercanopy spaces. Concordantly, predawn leaf water potential and growth of Stipa tenuis were higher or similar in intercanopy locations than in canopy locations. The physical presence of L. divaricata canopy frequently reduced soil moisture availability for understory plant growth, in part because of canopy interception of precipitation.Fil: Kröpfl, Alicia Inés. Universidad Nacional del Comahue. Centro Universidad Región Zona Atlántica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Cecchi, Gustavo A.. Instituto Nacional de Tecnología Agropecuaria. Estación Experimental Agropecuaria Valle Inferior; ArgentinaFil: Villasuso, Natalia M.. Universidad Nacional del Comahue. Centro Universidad Región Zona Atlántica; ArgentinaFil: Distel, Roberto Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiárida; Argentin

The impact of livestock grazing on the spatial pattern of vegetation in north-eastern Patagonia, Argentina

Background: The occurrence of shrub patches, alternating with either bare soil or low herbaceous cover, is a common feature in arid and semi-arid shrublands throughout the world. This patchy pattern of vegetation may result from water limitation, modulated by plant interactions; grazing (offtake and tramping) by livestock may cause further patchiness vegetation structure. Aims: We hypothesised that vegetation patchiness in the semi-arid shrublands of north-eastern Patagonia would be increased by livestock grazing, but not by positive interactions between adult plants of shrubs and grasses. Methods: We compared vegetation cover and pattern at three grazing intensities (exclosure, light and heavy grazing) and measured the growth of a representative shrub and grass in the presence and absence of the other to quantify the role of plant-to-plant interactions and its interaction with grazing for vegetation structure. Results: In the grazing exclosure and in moderately grazed areas, vegetation cover among shrub patches was larger, whereas the top cover of shrubs was lower than in the heavily grazed areas. We did not find any evidence of positive interactions between shrub and grass life forms. Conclusions: Our results were consistent with the hypothesis that livestock grazing increased the formation of patchy vegetation cover in arid and semi-arid shrublandsFil: Funk, Flavia Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiárida; ArgentinaFil: Peter, Guadalupe. Universidad Nacional de Río Negro; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Leder, Cintia Vanesa. Universidad Nacional de Río Negro; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Loydi, Alejandro. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiárida; ArgentinaFil: Kröpfl, Alicia Inés. Universidad Nacional del Comahue. Centro Universidad Región Zona Atlántica; ArgentinaFil: Distel, Roberto Alejandro. Universidad Nacional del Sur. Departamento de Agronomía; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiárida; Argentin

Forage provision is more affected by droughts in arid and semi-arid than in mesic rangelands

Droughts are projected to increase in magnitude, frequency and duration in the near future. In rangelands, the provision of valuable ecosystem services such as forage supply for livestock productivity is intimately linked to rainfall patterns, which makes it particularly vulnerable to droughts. Nonetheless, rangelands can differ in their sensitivity to droughts as shown by strong differences in the impacts of inter-annual precipitation changes on vegetation productivity in different sites. The aim of this study was to assess the sensitivity to droughts of nine rangelands located across a broad aridity gradient in Argentina, South America. We experimentally imposed comparable droughts under field conditions by reducing a fixed proportion of each incoming precipitation event within-year during three consecutive years and tracked changes in total aboveground and forage productivity. We found that arid and semi-arid rangelands were more severely impaired in their forage provision by drought than mesic rangelands, that is that sensitivity to drought declined as aridity decreased. Forage productivity decreased on average by c. 50%, in arid and semi-arid rangelands, whereas mesic sites did not exhibit significant changes between drought and control treatments. The negative impact in forage productivity of arid and semi-arid rangelands was mainly driven by the productivity reduction of few key plant species at each site. In seven of the nine rangelands, we found detrimental effects of drought on forage productivity during the first experimental-drought year, and in five of them the impact was further accentuated until the end of the experiment, which indicates how serious can these events be. Synthesis and applications. Our main findings indicate that the drought-induced impacts on forage provision are higher as aridity increases. This pattern highlights the urgent need to implement strategies to mitigate the detrimental consequences of drought, particularly in arid and semiarid rangelands, where forage provision is strongly associated with human well-being. Management approaches focused on key forage species, such as reducing the grazing pressure during drought periods according to these species' productivity dynamics can attenuate impacts on vulnerable ecosystems, preserving the rangelands' integrity while maintaining high long-term productivity levels.Fil: Bondaruk, Viviana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Oñatibia, Gastón Rafael. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Fernández, Roberto J.. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Agüero, Walter Fabian. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Catamarca-La Rioja. Estación Experimental Agropecuaria La Rioja; ArgentinaFil: Blanco, Lisandro Javier. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Catamarca-La Rioja. Estación Experimental Agropecuaria La Rioja; ArgentinaFil: Bruschetti, Martín. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Kröpfl, Alicia Inés. Universidad Nacional de Río Negro; ArgentinaFil: Loydi, Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiárida; ArgentinaFil: Pascual, Jesus Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Peri, Pablo Luis. Instituto Nacional de Tecnologia Agropecuaria. Centro Regional.patagonia Sur. Estacion Experimental Agropecuaria Santa Cruz. Agencia de Extension Rural Rio Gallegos.; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Peter, Guadalupe. Universidad Nacional de Río Negro; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Quiroga, Raul Emiliano. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Catamarca-La Rioja. Estación Experimental Agropecuaria La Rioja; ArgentinaFil: Yahdjian, María Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentin

Cambios en la provisión forrajera de pastizales naturales argentinos por sequías

Las sequías extremas se incrementarán en magnitud, frecuencia y duración en el futuro cercano, en particular en ecosistemas áridos y semiáridos. Los pastizales naturales brindan servicios ecosistémicos como la producción forrajera para ganadería cuya provisión se ve afectada por la disponibilidad de agua y es vulnerable a eventos extremos. Sin embargo, los pastizales pueden diferir en su sensibilidad a la sequía al manifestar diferentes impactos de la variabilidad interanual de la precipitación a la vegetación. El objetivo de este trabajo fue evaluar la sensibilidad a sequías extremas experimentales de pastizales ubicados a lo largo de un gradiente de aridez en Argentina. Durante tres años, se redujo experimentalmente la precipitación para simular sequías extremas en nueve sitios, y luego se determinaron sus cambios asociados en la producción forrajera. Los pastizales áridos y semiáridos exhibieron alta sensibilidad al ser los más afectados, donde específicamente su provisión forrajera disminuyó en promedio un 53% y 45% respectivamente, mientras que sitios mésicos no exhibieron reducciones significativas. Además, en el primer año encontramos efectos detrimentales en siete de nueve sitios, lo cual indica una seria amenaza de las sequías en pastizales naturales. La alta sensibilidad puede explicarse por la reducción de la productividad de las pocas especies claves determinantes del forraje en regiones áridas. Conocer la sensibilidad y el grado de alteración generado en pastizales por las sequías extremas es crítico para la prevención de la futura degradación de servicios ecosistémicos con importantes implicancias para el desarrollo económico y bienestar humano de las regiones evaluadas.Fil: Bondaruk, Viviana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Oñatibia, Gastón Rafael. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Fernández, Roberto. Universidad de Buenos Aires. Facultad de Agronomía; ArgentinaFil: Peri, Pablo Luis. Universidad Nacional de la Patagonia Austral; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Tecnología Agropecuaria; ArgentinaFil: Kröpfl, Alicia Inés. Universidad Nacional del Comahue; ArgentinaFil: Loydi, Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiárida; ArgentinaFil: Peter, Guadalupe. Universidad Nacional de Río Negro; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Comahue; ArgentinaFil: Blanco, Lisandro Javier. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Catamarca-La Rioja; ArgentinaFil: Quiroga, Emiliano Manuel. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Catamarca-La Rioja; ArgentinaFil: Agüero, Walter Fabian. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Catamarca-La Rioja; ArgentinaFil: Pascual, Jesus Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Bruschetti, Carlos Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Yahdjian, María Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaXXIX Reunión Argentina de EcologíaTucumanArgentinaAsociación Argentina de Ecologí

Extreme drought impacts have been underestimated in grasslands and shrublands globally.

Climate change is increasing the frequency and severity of short-term (~1 y) drought events-the most common duration of drought-globally. Yet the impact of this intensification of drought on ecosystem functioning remains poorly resolved. This is due in part to the widely disparate approaches ecologists have employed to study drought, variation in the severity and duration of drought studied, and differences among ecosystems in vegetation, edaphic and climatic attributes that can mediate drought impacts. To overcome these problems and better identify the factors that modulate drought responses, we used a coordinated distributed experiment to quantify the impact of short-term drought on grassland and shrubland ecosystems. With a standardized approach, we imposed ~a single year of drought at 100 sites on six continents. Here we show that loss of a foundational ecosystem function-aboveground net primary production (ANPP)-was 60% greater at sites that experienced statistically extreme drought (1-in-100-y event) vs. those sites where drought was nominal (historically more common) in magnitude (35% vs. 21%, respectively). This reduction in a key carbon cycle process with a single year of extreme drought greatly exceeds previously reported losses for grasslands and shrublands. Our global experiment also revealed high variability in drought response but that relative reductions in ANPP were greater in drier ecosystems and those with fewer plant species. Overall, our results demonstrate with unprecedented rigor that the global impacts of projected increases in drought severity have been significantly underestimated and that drier and less diverse sites are likely to be most vulnerable to extreme drought

Extreme drought impacts have been underestimated in grasslands and shrublands globally.

Climate change is increasing the frequency and severity of short-term (~1 y) drought events-the most common duration of drought-globally. Yet the impact of this intensification of drought on ecosystem functioning remains poorly resolved. This is due in part to the widely disparate approaches ecologists have employed to study drought, variation in the severity and duration of drought studied, and differences among ecosystems in vegetation, edaphic and climatic attributes that can mediate drought impacts. To overcome these problems and better identify the factors that modulate drought responses, we used a coordinated distributed experiment to quantify the impact of short-term drought on grassland and shrubland ecosystems. With a standardized approach, we imposed ~a single year of drought at 100 sites on six continents. Here we show that loss of a foundational ecosystem function-aboveground net primary production (ANPP)-was 60% greater at sites that experienced statistically extreme drought (1-in-100-y event) vs. those sites where drought was nominal (historically more common) in magnitude (35% vs. 21%, respectively). This reduction in a key carbon cycle process with a single year of extreme drought greatly exceeds previously reported losses for grasslands and shrublands. Our global experiment also revealed high variability in drought response but that relative reductions in ANPP were greater in drier ecosystems and those with fewer plant species. Overall, our results demonstrate with unprecedented rigor that the global impacts of projected increases in drought severity have been significantly underestimated and that drier and less diverse sites are likely to be most vulnerable to extreme drought

Extreme drought impacts have been underestimated in grasslands and shrublands globally

Altres Ajuts: Fundación Ramón Areces grant CIVP20A6621Climate change is increasing the frequency and severity of short-term (~1 y) drought events-the most common duration of drought-globally. Yet the impact of this intensification of drought on ecosystem functioning remains poorly resolved. This is due in part to the widely disparate approaches ecologists have employed to study drought, variation in the severity and duration of drought studied, and differences among ecosystems in vegetation, edaphic and climatic attributes that can mediate drought impacts. To overcome these problems and better identify the factors that modulate drought responses, we used a coordinated distributed experiment to quantify the impact of short-term drought on grassland and shrubland ecosystems. With a standardized approach, we imposed ~a single year of drought at 100 sites on six continents. Here we show that loss of a foundational ecosystem function-aboveground net primary production (ANPP)-was 60% greater at sites that experienced statistically extreme drought (1-in-100-y event) vs. those sites where drought was nominal (historically more common) in magnitude (35% vs. 21%, respectively). This reduction in a key carbon cycle process with a single year of extreme drought greatly exceeds previously reported losses for grasslands and shrublands. Our global experiment also revealed high variability in drought response but that relative reductions in ANPP were greater in drier ecosystems and those with fewer plant species. Overall, our results demonstrate with unprecedented rigor that the global impacts of projected increases in drought severity have been significantly underestimated and that drier and less diverse sites are likely to be most vulnerable to extreme drought