Regeneration of Polylepis australis Bitt. in the mountains of central Argentina

Enrico, Lucas; Funes, Guillermo; Cabido, Marcelo

doi:10.1016/j.foreco.2003.10.020

Cited by 48 publications

(65 citation statements)

References 37 publications

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“…They include both climatic factors such as temperature, humidity and radiation regimes during the growing season, and soil factors such as soil moisture, depth of the humus layer and soil texture, which affect water and nutrient availability at the soil surface and in the soil horizon (Rojo and Montero 1996). Topography, which influences temperature and water regimes (Madsen and Larsen 1997), understory cover (Dobrowolska 1998;Kitzberger 2000) and the formation of a soil seed bank (Enrico et al 2004) also significantly affect the establishment and survival of tree seedlings. The impact of herbivores (Paluch 2005), pathogens (Auspurguer 1983) and competition with grass (De Steven 1991) can hinder regeneration success.…”

Section: Introductionmentioning

confidence: 99%

Environmental influences on post-harvest natural regeneration of Pinus pinaster Ait. in Mediterranean forest stands submitted to the seed-tree selection method

2010

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Background:Research on natural regeneration is crucial for the development of sustainable forestry practices, in light of the global climate changes taking place. In this study one hundred and fifty-one plots were sampled in six Pinus pinaster stands that were naturally regenerated by the seed-tree method in Mediterranean forests in central Spain. Objective:The objectives of the survey were to study the suitability of different forest stands designated for natural regeneration as well as to analyse seedling establishment and the relationship between regeneration and different site factors. Analysis of variance (ANOVA) and multivariate analysis with canonical ordination techniques were employed. Full and partial redundancy analyses (RDAs) on a correlation matrix were used to carry out a direct gradient analysis of regeneration density as a function of site factors.Results: Nearly all stands presented seedling densities over 2000 seedlings/ha and were thus found to be suitable for natural regeneration of Pinus pinaster by the seed-tree selection method. Significant variables that best explained total seedling and viable seedling density were spring and autumn precipitation of the year prior to establishment, spring and summer precipitation of the year of establishment, and percentage cover of litter. There were no signs of competition between shrubs and seedlings, but a negative significant correlation with grass cover was observed. Pinus pinaster natural regeneration was successful with the seed-tree method, although it appeared to be highly dependent on climate and stand conditions.

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Section: Introductionmentioning

confidence: 99%

Environmental influences on post-harvest natural regeneration of Pinus pinaster Ait. in Mediterranean forest stands submitted to the seed-tree selection method

2010

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“…Higher G ST and PhiPT values among populations of juveniles relative to adults, as well as some degree of structure between age classes, could be explained N is the number of individuals per population, H T is the total genetic diversity for the species, H S is the mean within-population genetic diversity, G ST is the proportion of the total genetic diversity found among populations a Original 12 populations corresponding to the 12 forest patches sampled b The 12 populations sampled pooled across populations, within watershed by the very patchy occurrence of seedlings, with most of them restricted to relatively few canopy gaps (S. Aragundi personal observation, Enrico et al 2004). As a result, the seedlings sampled may have been progeny of relatively few widely scattered adults.…”

Section: Discussionmentioning

confidence: 99%

“…The absence of such structure in populations of mature individuals is consistent with theoretical predictions for tree populations which are characterized by generally low genetic structure (Hamrick andGodt 1989, 1996;Nybom 2004). High seedling mortality (observed in Polylepis incana, P. pauta, [Cierjacks et al 2007], and P. australis [Enrico et al 2004]) and delayed reproductive maturity in trees could contribute to the attenuation of structure over time (Austerlitz et al 2000;Le Corre and Kramer 2003). No correlation was found between geographic distance and genetic differentiation, and clustering of populations on the basis of genetic affinity often revealed higher genetic similarity between populations in different basins, which may have been caused by greater gene exchange between river basins.…”

Section: Discussionmentioning

confidence: 99%

Genetic insights into the historical distribution of Polylepis pauta (Rosaceae) in the northeastern Cordillera Oriental of Ecuador

2010

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Scattered patches of Polylepis forest that occur within the 3,000-4,500 m altitudinal belt of the Andean Cordillera from Venezuela to Argentina have been hypothesized to be remnants of once continuous forests whose range became fragmented through anthropogenic activities that probably preceded the Spanish conquest. Allozyme variation of Polylepis pauta from 12 forest populations in three adjacent watersheds in Northeastern Ecuador was investigated to assess whether observed patterns of gene diversity were consistent with a more continuous historical range of the species and to evaluate the populations' potential for restoration. Genetic diversity and polymorphism in P. pauta populations were higher than mean values for most wind pollinated and dispersed temperate and tropical tree species with regional distributions. Genetic differentiation among watersheds was lower than among populations within each watershed. Isolation by distance was not evident and several populations from different watersheds were more genetically similar than populations from the same watershed. Larger forest patches with broader altitudinal ranges had more alleles. Forest patches on steeper slopes and at higher elevations supported populations with less genetic diversity; this might have resulted from the predominance of vegetative reproduction in these landslide prone areas. The amount of genetic diversity maintained by P. pauta, coupled with low genetic differentiation among populations within and among watersheds, is consistent with a more continuous historical range of the species in Northeastern Ecuador and point to the Oyacachi basin as having the highest levels of genetic diversity.

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“…Moreover, diameter distribution suggests poor sapling recruitment as stems of diameter class 0-10 cm represented only less than 50% of the overall stem number at all altitudinal levels. Studies of Enrico et al (2004) on woodlands of P. australis in Argentina, describe comparable diameter distribution patterns. Such population structures within forest stands are typical for shade-intolerant species that do not successfully regenerate below a closed canopy (e.g.…”

Section: Impact Of Tramplingmentioning

confidence: 92%

Effects of altitude and livestock on the regeneration of two tree line forming Polylepis species in Ecuador

et al. 2007

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Regeneration is known to be limited at many temperate tree lines, but very little data is available on the impacts of altitude and anthropogenic disturbance on regeneration patterns along tropical tree lines. The study focused on the reproductive traits of two Polylepis species in the Páramo de Papallacta in Ecuador along an altitudinal gradient, and involved different intensities of cattle trampling within subsequent altitudinal ranges. We analyzed flowering, fruit set, seed viability, germination, and seedling establishment as well as stand structure of Polylepis incana and P. pauta. The numbers of P. incana inflorescences and seedlings per m 2 showed a marginally significant decrease with increasing altitude. Mean tree height was significantly lower at higher altitudes, while stem number increased. The number of P. pauta inflorescences also decreased significantly upslope. In both forest types, trampling was found to have a positive impact on seedling abundance, presumably due to the removal of the litter layer. Thus, there was no evidence of negative effects of moderate cattle grazing on both tree line species. However, sapling establishment was minimal inside the forest stands at all altitudes and grazing levels, and we consequently observed a low proportion of narrow stems within all investigated forests. Our results show that, along with vegetative growth limitations of adult trees, important regeneration traits such as seedling and inflorescence numbers are also influenced by altitude, which might contribute to the formation of the upper tree line. Nevertheless, recruitment in the forest interior was low overall indicating that further factors, such as light conditions, affect regeneration of the studied species.

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Regeneration of Polylepis australis Bitt. in the mountains of central Argentina

Cited by 48 publications

References 37 publications

Environmental influences on post-harvest natural regeneration of Pinus pinaster Ait. in Mediterranean forest stands submitted to the seed-tree selection method

Environmental influences on post-harvest natural regeneration of Pinus pinaster Ait. in Mediterranean forest stands submitted to the seed-tree selection method

Genetic insights into the historical distribution of Polylepis pauta (Rosaceae) in the northeastern Cordillera Oriental of Ecuador

Effects of altitude and livestock on the regeneration of two tree line forming Polylepis species in Ecuador

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