Combined effects of environment and grazing on vegetation structure in Argentine granite grasslands

Cingolani, Ana M.; Cabido, Marcelo; Renison, Daniel; Neffa, Viviana Solís

doi:10.1658/1100-9233(2003)014[0223:ceoeag]2.0.co;2

Cited by 58 publications

(111 citation statements)

References 30 publications

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“…The landscape of the Córdoba Mountains, Argentina is a mosaic of diVerent types of tall tussock grasslands, grazing and hydromorphic lawns, natural granitic outcrops, exposed rock surfaces produced by soil erosion as a consequence of excessive livestock densities, and open-canopy forests, which are dominated by P. australis (Rosaceae) trees (Cingolani et al 2004(Cingolani et al , 2007. The forests are often associated with steep areas with rock outcrops, because these sites are less aVected by browsing and Wres (Renison et al 2002;Teich et al 2005;Renison et al 2006).…”

Section: Study Areamentioning

confidence: 99%

“…This study was conducted within the "Condorito" (31°37/40Ј S, 64°40/46Ј W) and "Tabaquillo" (32°02/04Ј S, 64°49/56Ј W) river basins (37,400 ha-linear distance between both basins was approximately 45 km) where P. australis individuals are found both in protected rocky areas and in areas with more favourable soil conditions but with greater interference by livestock and Wres (Cingolani et al 2004;Renison et al 2006). We sampled 140 trees separated by a distance of between 0.5 and 10 km, and we made an eVort to select as wide a range of tree sizes and site characteristics as possible.…”

Section: Data Collectionmentioning

confidence: 99%

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Age–size–habitat relationships for Polylepis australis: dealing with endangered forest ecosystems

et al. 2008

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Assessing tree ages is important for the understanding of forest recruitment patterns and tree growth. However, little experience exists in the subtropics and accurate aging usually involves potentially damaging techniques such as tree coring or even the use of entire cross sections, which is not recommendable in endangered species or ecosystems. We provide an example of how age may be predicted on the basis of tree size and site conditions, using Polylepis australis of Central Argentina. Our study was conducted in two entire river basins where 96 independent trees were successfully cored for age analysis. Site and tree characteristics were registered and tree age determined through standard dendrochronological techniques. The multiple regression procedure selected tree circumference and proportion of rock under the tree canopy as signiWcant variables explaining 48% of the variation in number of growth rings. Trees surrounded by rock clearly grew slower than those surrounded by a higher proportion of soil and vegetation. A comparison with a one site study shows that the ability to predict P. australis age is clearly reduced when geographical range is extended but the explanatory power of our model is still high enough for certain applications and within the range of other one site studies. We suggest that tree size and site characteristics may be used to predict age in other subtropical mountain forests with a well marked growth season.

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Section: Study Areamentioning

confidence: 99%

Section: Data Collectionmentioning

confidence: 99%

Age–size–habitat relationships for Polylepis australis: dealing with endangered forest ecosystems

et al. 2008

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“…The study was performed in Quebrada del Condorito National Park, where domestic livestock are maintained in some areas to preserve vegetation patchiness and hence plant biodiversity . When grazed by large herbivores, the landscape presents a mosaic of lawn patches and closed and open tussocks grasslands with species of different foliar quality (Cingolani et al, 2003Vaieretti et al, 2013). Lawns, where herbivores tend to congregate, are dominated by short palatable plant species such as forbs and graminoids, with high nutrient content and foliar attributes suggesting high relative growth rates.…”

Section: Study Areamentioning

confidence: 99%

Scaling-up from species to ecosystems: How close can we get to actual decomposition?

et al. 2015

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“…Some case studies have indicated that complete exclusion of livestock in South American mountains may lead to a decline in plant and bird diversity (Cingolani et al 2003;Garcı´a et al 2008), and studies in Africa have shown that forest regeneration may even decline with the complete exclusion of livestock (Reed and Clokie 2000). In South America, Cierjacks et al (2008) found no evidence suggesting that the regeneration of Polylepis incana and P. pauta at the upper tree line in Ecuador is negatively affected by moderate cattle grazing.…”

Section: Introductionmentioning

confidence: 99%

Do we need livestock grazing to promote Polylepis australis tree recruitment in the Central Argentinean Mountains?

Zimmermann

Renison

Leyer

et al. 2009

Ecological Research

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South American Polylepis mountain forests are endangered due to centuries of logging, fire clearance, and intensive livestock grazing. Polylepis australis (Rosaceae) dominates the tree canopy in the Central Argentinean Mountains, where livestock have been excluded or reduced to very low densities over wide areas. Lowered plant and bird diversity in these abandoned grazing areas suggest that some livestock grazing may be beneficial for conservation purposes. Our study aimed to determine whether this may also be true for forest regeneration. In 300 plots of 1 m 2 distributed in subregions of high to moderate grazing pressure as well as grazing exclusion, we recorded the presence of P. australis seedlings and grazing indicators. Topographical parameters as well as vegetation and soil characteristics were also assessed. Seedling frequencies were highest in the region with moderate grazing, intermediate with grazing exclusion, and the lowest with high grazing pressures. Logistic regression models revealed that seedling occurrence was highest close to seeder trees, with intermediate litter coverage and at intermediate altitudes above sea level. Since grazing ultimately affects seeder tree occurrence through browsing and reduces litter cover and predominates in higher areas, we conclude that grazing is an important driving factor for P. australis regeneration. We confirm previous studies determining high grazing pressure to be detrimental for P. australis regeneration, but also provide data suggesting that its complete exclusion may not be recommendable either. Management should aim to alternate between a moderate grazing intensity to promote seedling recruitment, with subsequent exclusion to accelerate the growth of the established seedlings.

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Combined effects of environment and grazing on vegetation structure in Argentine granite grasslands

Cited by 58 publications

References 30 publications

Age–size–habitat relationships for Polylepis australis: dealing with endangered forest ecosystems

Age–size–habitat relationships for Polylepis australis: dealing with endangered forest ecosystems

Scaling-up from species to ecosystems: How close can we get to actual decomposition?

Do we need livestock grazing to promote Polylepis australis tree recruitment in the Central Argentinean Mountains?

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