Structural and nutritional heterogeneity of riparian vegetation in Patagonia (Argentina) in relation to seasonal grazing by sheep

Utrilla, Victor Ricardo; Brizuela, M. A.; Cibils, Andrés F.

doi:10.1016/j.jaridenv.2006.03.016

Cited by 12 publications

(5 citation statements)

References 23 publications

(21 reference statements)

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“…Holland (2002) irrigated senita cactus ( Pachycereus schottii ) and found positive effects of senita moths ( Upiga virescens ) on cactus reproduction, but no effect of water availability on moth pollination or larval fruit consumption. Also, Utrilla, Brizuela & Cibils (2006) found no net effect of a sheep ( Ovis aries ) population on vegetation populations, regardless of soil moisture.…”

Section: Linking Water Availability To Species Interactions In Drmentioning

confidence: 87%

Shifting species interactions in terrestrial dryland ecosystems under altered water availability and climate change

et al. 2011

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Species interactions play key roles in linking the responses of populations, communities, and ecosystems to environmental change. For instance, species interactions are an important determinant of the complexity of changes in trophic biomass with variation in resources. Water resources are a major driver of terrestrial ecology and climate change is expected to greatly alter the distribution of this critical resource. While previous studies have documented strong effects of global environmental change on species interactions in general, responses can vary from region to region. Dryland ecosystems occupy more than one-third of the Earth's land mass, are greatly affected by changes in water availability, and are predicted to be hotspots of climate change. Thus, it is imperative to understand the effects of environmental change on these globally significant ecosystems. Here, we review studies of the responses of population-level plant-plant, plant-herbivore, and predator-prey interactions to changes in water availability in dryland environments in order to develop new hypotheses and predictions to guide future research. To help explain patterns of interaction outcomes, we developed a conceptual model that views interaction outcomes as shifting between (1) competition and facilitation (plant-plant), (2) herbivory, neutralism, or mutualism (plant-herbivore), or (3) neutralism and predation (predator-prey), as water availability crosses physiological, behavioural, or population-density thresholds. We link our conceptual model to hypothetical scenarios of current and future water availability to make testable predictions about the influence of changes in water availability on species interactions. We also examine potential implications of our conceptual model for the relative importance of top-down effects and the linearity of patterns of change in trophic biomass with changes in water availability. Finally, we highlight key research needs and some possible broader impacts of our findings. Overall, we hope to stimulate and guide future research that links changes in water availability to patterns of species interactions and the dynamics of populations and communities in dryland ecosystems.

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Section: Linking Water Availability To Species Interactions In Drmentioning

confidence: 87%

Shifting species interactions in terrestrial dryland ecosystems under altered water availability and climate change

et al. 2011

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“…Dwarf shrubs (Azorella trifurcata) can become dominant in the outlying areas of degraded mallines (Bonvissuto and Somlo 1997). Forage production of this community is 1,000-2,000 kg DM ha -1 (Bonvissuto and Somlo 1998;Siffredi et al 2005;Utrilla et al 2005Utrilla et al , 2006. (Cantero et al 1998).…”

Section: Discussionmentioning

confidence: 99%

“…Thus is due to local effects of unmeasured (biotic or abiotic) controlling variables. This may be related, in part, to grazing history since mallines have a high quantity and quality of available forage (relative to drylands surrounding areas) that result in high herbivore preference for these ecosystems a phenomenon that often leads to changes in vegetation composition (del Valle 1993;Bonvissuto and Somlo 1997;Utrilla et al 2006).…”

Section: Discussionmentioning

confidence: 99%

Vegetation composition and its relationship with the environment in mallines of north Patagonia, Argentina

Gaitán

López

Bran

2010

Wetlands Ecol Manage

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Mallines'' are characteristic Patagonian wet meadows. The objectives of this study were to describe plant community composition in the main mallines in northern Patagonia and to determine the influence of selected environmental variables on the distribution of vegetation. Fifty-two sites were selected for vegetation surveys and measurements of water table (WT) depth, soil pH, electric conductivity (EC), and mean annual precipitation. We performed cluster analysis for vegetation classification and correspondence analysis (CA) and canonical correspondence analysis (CCA) for vegetation ordination. Plant composition was mostly related to both environmental variables and longitude and that it was not possible to disentangle the two (i.e. the vegetation was spatially structured). We defined three plant communities that differed along two main environmental gradients. The main gradient operates on a regional scale and is determined, from west to east, by a decrease in mean annual precipitation and an increase in the depth of the WT, soil pH, and EC. The secondary gradient operates on a site scale and is determined by topographic features inside the mallín and their influence on the hydrological regime (increasing moisture from the border towards the center). This second gradient allowed us to distinguish two plant communities, one of wet characteristics in the centers of the mallín, and another of mesic characteristics along the borders of the mallín.

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“…Los índices de biodiversidad florística más altos correspondieron a las geoformas de Ladera Sur y Norte respectivamente, en comparación a la geoforma Depresión (Vega), donde se puede apreciar una presión antropogénica, debido a la intensidad del pastoreo. Esto ha causado la homogeneidad florística en términos de riqueza y cobertura, al existir tres especies dominantes, dos nativas (Agrostis meyenii y Hordeum pubiflorum) y una introducida (Taraxacum officinale); esto se aprecia en los resultados arrojados por los índices de Dominancia y Shannon, lo cual se ajusta a otros estudios realizados en vegas o mallines en Argentina, que evidencian el efecto del pastoreo (Boelcke et al 1985;Oliva et al 2001;Utrilla et al 2006;Suárez et al 2010;Bertani, 2011). Lo anterior estaría indicando que el sobrepastoreo genera efectos evidentes que se manifiestan en cambios en la vegetación, al sustituirse especies por otros taxones que son propios de sectores áridos.…”

Section: Discussionunclassified

Caracterización de la composición y estructura florística en las geoformas asociadas a una vega, en el Centro Regional de Investigación - INIA Kampenaike, en la región de Magallanes, Chile

Díaz

Ivelic-Sáez

2020

Anales Instituto Patagonia (Chile)

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Structural and nutritional heterogeneity of riparian vegetation in Patagonia (Argentina) in relation to seasonal grazing by sheep

Cited by 12 publications

References 23 publications

Shifting species interactions in terrestrial dryland ecosystems under altered water availability and climate change

Shifting species interactions in terrestrial dryland ecosystems under altered water availability and climate change

Vegetation composition and its relationship with the environment in mallines of north Patagonia, Argentina

Caracterización de la composición y estructura florística en las geoformas asociadas a una vega, en el Centro Regional de Investigación - INIA Kampenaike, en la región de Magallanes, Chile

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