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Post-fire forest restoration is increasingly demanded with the aim of reducing post-fire soil erosion and accelerating forest recovery. Under the hypothesis that Acacia caven, a dominant species in disturbed woodlands, is more tolerant to environmental post-fire conditions than Lithraea molleoides, a dominant species in preserved forests, we assessed the performance of seedlings outplanted to burnt and unburnt areas in three sites of the Córdoba mountains. We registered the survival and growth two years after planting. Survival varied between 24 and 92% according to treatment, without differences between species and between burnt and unburnt areas but with significant differences among sites (P<0.001). The growth was variable; in some treatments, seedlings had a mean height lower than plantation height, while in other treatments, seedlings grew up to double its initial height, without differences between burnt and unburnt areas. L. molleoides growth was higher than A. caven growth (11.4±1.4 cm and -2.3±2.0 cm, respectively) and varied among planting sites (P<0.001). Contrary to expectations, both species had similar performances in burnt and unburnt areas, while the main differences occurred among sites. To attain restoration goals we recommend planting the dominant species in preserved forest as the dominant species in disturbed woodlands is widely distributed in the region. Our results highlight the importance of studying in each site which species are most adequate to optimize restoration efforts in highly heterogeneous forest as Chaco Serrano. [ABSTRACT FROM AUTHOR]

In fire-prone landscapes, differences in post-fire regeneration by resprouting between species or sites could be far more important in explaining vegetation physiognomy and composition than seed regeneration. This is the first study exploring the relative contribution of tree resprouts and seeds to post-fire crown volume in the Chaco Serrano forest of South America. Additionally, we compare the resprouting response among species and quantify post-fire changes in tree composition among sites. We established 290 permanent plots distributed in three sites affected by wildfires in 2005. For all tree species in all plots we recorded survival of every individual 1 year after the fire; at the plot level, we recorded the above-ground tree volume before and 3 years after the fire. Resprouting from the base was the main resprouting type. Survival varied between species from 73% to 100% for native species and from 7% to 100% for non-natives. Before the fire, crown volume was similar in the three sites, and was completely lost after the fire in 92% of the plots. Three years after the fire, between 8% and 58% of crown volume was recovered. The ratio of crown recovery because of resprouts and seedlings was 1562:1. Tree composition exhibited few changes because of the high post-fire survival of most native species. We conclude that in the semiarid Chaco Serrano ecosystem tree species regenerate mainly by resprouting. This regeneration mode should be taken into account to better understand post-fire successional pathways of these forests, their management and the restoration of burnt forest areas. [ABSTRACT FROM AUTHOR]

Abstract: Establishment of Polylepis forests endemic to the mountains of South America may be affected by seed dispersal, site characteristics and livestock density. Polylepis australis (“tabaquillo”) grows in the high mountains of central Argentina, where we set up 76 square study plots of 900m2. To determine dispersal distance, we distributed 6 seed traps per plot in and around 20 plots. To determine the best site characteristics and livestock stoking rates, at two river basins differing in historic stocking rates, we analyzed the presence of seedlings in 56 plots and recorded topography, vegetation types and indicators of livestock activity. We also measured microsite characteristics in a sample of 32 comparable pairs of 1m2 quadrats, with and without seedlings. Maximum recorded dispersal distance of P. australis seeds was 6m, and seedlings were found no more than 10m from seed trees. The numbers of seedlings and seed trees were 3.5 and 4 times higher, respectively, in the basin with less livestock. At the 900m2 plot scale, a Poisson regression indicated a positive relationship between seedling number and P. australis canopy cover. At the quadrat scale (1m2), seedlings were found in quadrats with significantly lower evidence of soil erosion than comparison quadrats without seedlings. We conclude that the main limitations to recruitment are short seed dispersal distances, lack of seed trees and extreme soil erosion. Management should therefore aim at preserving seed trees and reducing livestock density to prevent erosion. [Copyright &y& Elsevier]