Environmental history and forest regeneration dynamics in a degraded valley of north-west Argentina's cloud forests

Grau, H. Ricardo; Carilla, Julieta; Gil-Montero, R.; Villalba, Ricardo; Aráoz, Ezequiel; Massé, Guillaume; Membiela, Mónica de

doi:10.1017/cbo9780511778384.064

Cited by 5 publications

(10 citation statements)

References 19 publications

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“…On the other hand, current changes in land use can modify over time the distribution and extent of forest successional stages in the landscape. Andean cloud forests in northwestern Argentina show a tendency to the abandonment of agricultural and grazing lands and recovery of secondary forest associated to decreasing rural population (Izquierdo and Grau, 2009;Grau et al, 2010). Under this scenario, secondary forests will progress in the succession to old-growth forests, where recruitment of P. parlatorei is negligible.…”

Section: Discussionmentioning

confidence: 99%

“…Cloud forests in the Southern Yungas of Bolivia and Argentina have undergone degradation and transformation as a consequence of logging, grazing, fire management and farming (Navarro and Maldonado, 2002;Grau et al, 2010), leading to the ban of the international trade of P. parlatorei since 1975 (UNEP-WCMC, 2015), among other conservation measures. Being a pioneer but very long-lived tree, which persists as a dominant species thorough most successional stages, this conifer plays an important role in the cloud forest dynamics and in the recruitment of other plant species (Arturi et al, 1998;Ramadori, 1998;Carilla and Grau, 2010), and is a key resource for wildlife (Ruggera et al, 2011;Pidgeon et al, 2015).…”

Section: Implications For Conservationmentioning

confidence: 99%

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Functional Equivalence in Seed Dispersal Effectiveness of Podocarpus parlatorei in Andean Fruit-Eating Bird Assemblages

Blendinger

2017

Front. Ecol. Evol.

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Most fleshy-fruited plants establish strong local interactions with a few fruit-eating species across their distribution range, which can differ among sites and have a major impact for the plant population dynamics. In turn, human disturbances alter both the original animal assemblage with which plants interact and the outcome of the mutualistic interaction. Negative consequences of human disturbances can be weakened when different seed dispersers exert similar effects on plant populations, being functionally equivalent. To understand the consequences of variability in seed dispersers on the recruitment of a long-lived tree species, I assessed changes in the assemblages of avian dispersers of Podocarpus parlatorei in subtropical Andean cloud-forests, and how these changes affect the outcome of the interaction at different spatial scales. The seed dispersal effectiveness (SDE) concept, defined as the likelihood of a seed removed by a fruit-eating bird to be dispersed to a suitable site for seed survival and germination, provides the framework to compare the contributions of different birds to seed dispersal. I compared the SDE in two old-growth forests dominated by P. parlatorei and a human disturbed forest, and in the main habitat types of these sites. In all sites, highest SDE values were provided by "gulpers" that swallow the whole fleshy cone ("fruit"), predominantly Elaenia and Turdus species. SDE was highest in forest edges and secondary forests, and negligible in other habitats. Equivalence in SDE was relatively low both within and between forest sites. Human forest disturbance modified the functional equivalence, the generalization in mutualistic interactions and the strength of SDE. Secondary forests showed the higher SDE and the greater richness of dispersers high in SDE; as a consequence, the ecological equivalence increased in the most suitable habitat for recruitment. This could lead to greater resilience of plant populations to local extinctions of dispersers, and allows the recovery of human disturbed forests. This study shows that in the replacement of functional equivalent species, the outcomes of the interactions are strongly affected by disperser abundance and habitat use, at the expense of dispersers' trait redundancy on plant population dynamics and community structure.

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Section: Discussionmentioning

confidence: 99%

Section: Implications For Conservationmentioning

confidence: 99%

Functional Equivalence in Seed Dispersal Effectiveness of Podocarpus parlatorei in Andean Fruit-Eating Bird Assemblages

Blendinger

2017

Front. Ecol. Evol.

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“…The usefulness of management strategies of this type has been demonstrated in temperate forests (including Fagus spp.) in various regions around the world (Peters 1997, Grau et al 2010, von Oheimb et al 2007.…”

Section: Discussionmentioning

confidence: 99%

Population structure of Fagus grandifolia subsp. mexicana in the cloud forest of Hidalgo State, Mexico

Ortiz-Quijano¹,

Sánchez–González²,

López–Mata³

et al. 2016

Bot. Sci.

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The highest densities and largest areas of Fagus grandifolia subsp. mexicana in Mexico grow in the cloud forest of the state of Hidalgo. Although this taxon is endangered, there is little information about its population structure. This study provides data on the structure of heights, diameters and ages of Fagus in three populations in Hidalgo. Additionally, information was obtained on the structure of the beech forests, whose canopy is dominated by Fagus. At each locality, three to five 400 m 2 sample plots, depending on the size of the respective forest, were randomly selected. Within each plot, density and basal area of each species of tree and shrub with diameter greater than 2.5 cm (1.30 m) were estimated. At the species level, populations are dynamic, with a high percentage of young individuals; however, at one of the localities, changes have occurred in the last decade due to anthropogenic activity, and the structure of sizes and diameters in the youngest age categories has changed. Diameter was a good indicator of the age of the trees. At the community level, the dominance of Fagus and other species differed between localities, which is probably related to the degree of disturbance. Population and community structure are related and could be considered as indicators of changes in environmental conditions in the recent past and today. Key words: Age structure, cloud forest, diameter classes, dendrochronology, Fagus grandifolia subsp. mexicana Estructura poblacional de Fagus grandifolia subsp. mexicana en el bosque mesó-filo de montaña del estado de Hidalgo, México Resumen Las poblaciones de Fagus grandifolia subsp. mexicana con mayor densidad de individuos y con mayor extensión territorial de México se desarrollan en el bosque mesófilo de montaña del estado de Hidalgo; dado que este taxón se considera en riesgo de extinción, el objetivo del presente estudio fue aportar datos sobre su estructura de alturas, diámetros y edades en tres poblaciones de Hidalgo. Adicionalmente, se obtuvo información sobre la estructura de los bosques de haya, en los que Fagus domina el dosel. En cada localidad se establecieron al azar entre 3 y 5 parcelas de muestreo de 400 m 2 cada una, dependiendo del tamaño de cada bosque. Dentro de cada parcela se estimó la densidad y área basal de cada especie de árbol y arbusto con diámetro mayor a 2.5 cm, a 1.30 m de altura. A nivel específico, las poblaciones son dinámicas, con un alto porcentaje de individuos jóvenes; sin embargo, en una de las localidades, han ocurrido cambios en la última década por actividades antropogénicas y la estructura de alturas y diámetros en las primeras categorías de edad se ha modificado; el diámetro resultó ser un buen predictor de la edad de los árboles. A nivel comunitario, la dominancia de Fagus y otras especies difirió entre localidades, lo que probablemente se relacione con el grado de perturbación. La estructura poblacional y comunitaria están relacionadas y podrían ser consideradas como indicadoras de cambios en las condiciones ambientales ...

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“…Regional climate change is characterized by an increase in rainfall since the late 1950s (Minetti & Vargas 1997, Villalba et al 1998). Despite these trends (less grazing, more rainfall), potentially favorable to forest recovery, a clear forest transition is not observed in the study site (Grau et al 2010). Based on these observations, we hypothesized that the dynamic of forest–grassland ecotone is controlled by the complex interactions among grazing, fire, climate and vegetation dynamics, and that due to the effects of recurrent fires, degraded grasslands persist as an alternative degraded state which resists tree invasion despite improving conditions of land use and climate.…”

mentioning

confidence: 83%

“…According to our hypothesis, tree recruitment is largely limited by fire; therefore, tree establishment should be positively related to factors that reduce fuel availability. Since grazing has decreased in the region (Grau et al 2010), tree establishment should be decreasing through time during the 20th century (P1.1), and in recent times tree establishment should be more intense near the township (P1.2), where higher grazing intensity reduces fire frequency. Since rainfall is likely to increase fuel availability and fire probability, tree establishment should be negatively related to rainfall (P1.3).…”

mentioning

confidence: 99%

150 Years of Tree Establishment, Land Use and Climate Change in Montane Grasslands, Northwest Argentina

Carilla

Grau

2010

Biotropica

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Degraded grasslands resulting from intensive land use appear to be highly resistant to tree invasion due to interactions between land use, climate, grazing and fire. We describe long-term patterns of tropical montane forest regeneration into degraded grasslands and analyze their relationships with historical changes in rainfall, grazing and fire in Los Toldos valley (Northwest Argentina), cloud forest life zone (1600 m asl). We used dendrochronological techniques to reconstruct spatial and temporal patterns of Podocarpus parlatorei establishment (the dominant tree species in secondary forests) and grassland fires for the last 150 yr. We assessed current livestock spatial distribution along the valley through feces sampling. Inferred tree establishment patterns (i.e., considering age structure and mortality) were analyzed in relation to temporal and spatial patterns of grazing and fire derived from our own analyses and from government statistics, and to rainfall patterns derived from previous dendrochronological reconstructions. Current grazing intensity was higher close to the local township. Fire occurrence increased with periods of above-average rainfall (higher fuel productivity), and tended to increase with distance to township (less grazing). Tree establishment in grasslands was spatially associated with high grazing intensity and low fire frequency, and temporally associated with periods of high grazing intensity and below-average rainfall. Despite climatic and land-use changes leading to conditions potentially favorable for trees (i.e., more rainfall, less grazing), grasslands persist in this study area, likely due to the direct (saplings burning) and indirect (soil degradation and desiccation) effects of recurrent fires, enhanced by decreasing grazing and increasing rainfall.Abstract in Spanish is available at

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Environmental history and forest regeneration dynamics in a degraded valley of north-west Argentina's cloud forests

Cited by 5 publications

References 19 publications

Functional Equivalence in Seed Dispersal Effectiveness of Podocarpus parlatorei in Andean Fruit-Eating Bird Assemblages

Functional Equivalence in Seed Dispersal Effectiveness of Podocarpus parlatorei in Andean Fruit-Eating Bird Assemblages

Population structure of Fagus grandifolia subsp. mexicana in the cloud forest of Hidalgo State, Mexico

150 Years of Tree Establishment, Land Use and Climate Change in Montane Grasslands, Northwest Argentina

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