Effects of Post-Fire Plant Cover in the Performance of Two Cordilleran Cypress (Austrocedrus chilensis) Seedling Stocktypes Planted in Burned Forests of Northeastern Patagonia, Argentina

Abstract

Cordilleran cypress (Austrocedrus chilensis [D.Don] Pic. Serm. et Bizarri) forests occupy 140,000 ha along a sharp environmental gradient of central Andean-Patagonia in Argentina. Every summer, about 3200 ha of these forests are affected by wildfires, taking thereafter long time to recover. To accelerate forest recovery, we determined in xeric and mesic cypress stands burned 5 and 2 year before whether survival and growth of two planted cypress seedling stocktypes are affected by plant cover and contrasting precipitation conditions. Two experiments were conducted on each site, involving 100 replicates of two seedling stocktypes, having each significantly different morphological attributes. The experiments comprised a dry and humid growing season on each site. Both stocktypes performed similarly within stands, but differently between stands. In the xeric stand, plant cover had neutral effects on seedling survival, favored seedling height growth in the dry season, and was negative on collar diameter and stem growth. In the mesic site, high plant cover favored survival and height growth, but was inconsequential for collar diameter and stem growth. In this short-term post-fire period, and independent of precipitation received during both seasons (dry or humid), plant cover appears as playing a facilitative role, having neutral or even positive effects on survival and growth of planted seedlings. During the early post-fire successional stages, and besides seedling stocktype, there was a synergistic balance between light and soil moisture that seems to benefit planted seedling performance in burned cypress forests, and especially in mesic sites.

Restoration of burned and post-fire logged Austrocedrus chilensis stands in Patagonia: effects of competition and environmental conditions on seedling survival and growth

“…However, competition might affect growth in a great variety of ways, and it may differ among communities (Reader et al 1994). In a mesic area similar to our study site, A. chilensis seedling survival and growth were positively associated with post-fire cover during the 2 years after plantation (Urretavizcaya et al 2017). In our study, however, this nursing effect appeared two seasons after acclimation.…”

“…However, in order to guarantee the establishment of the target species, restoration practices sometimes require additional microsite manipulation to avoid or diminish any deleterious biotic or micro-environmental effects on planted seedlings (Whisenant 1999). These effects are mainly caused by competition for soil water or nutrients by early successional herbaceous vegetation, excessive soil heating by higher incoming radiation reaching denuded soils, or by the lack of nurse plants (generally shrubs or half-shrubs) that protect seedlings from excessive temperature fluctuations (Padilla and Pugnaire 2006;Urretavizcaya et al 2017). Forest-productivity research has identified interactions between competing vegetation and logging debris left after forest harvesting.…”

Crecimiento de <i>Austrocedrus chilensis</i> y <i>Nothofagus dombeyi</i> en bosques mixtos y condiciones ambientales para el desarrollo de sus renovales: contribuciones al manejo de rodales afectados por el mal del ciprés

“…Del Campo et al (2006) mostraron a su vez, que dentro de los protectores se produce un efecto de condensación, que puede mejorar la humedad alrededor de las plantas. En este estudio la protección artificial sólo tuvo un efecto negativo en el sitio mésico sobre el crecimiento en diámetro (de un 20% respecto a plantas sin protección), mientras que en la supervivencia y el incremento en altura no se observó efecto, esto último coincidiendo con lo reportado para el ciprés por Urretavizcaya et al (2017).…”

“…Estos resultados coinciden con la tendencia reportada para el crecimiento en altura de ciprés por Urretavizcaya et al (2017) y de ambas especies por Pafundi et al (2016).…”

“…efectos están causados por la competencia por agua o nutrientes en el suelo por parte de la vegetación herbácea, por la falta de plantas nodrizas que protejan a las plantas de interés de fluctuaciones de temperatura excesivas y/o por excesivo calentamiento por alta radiación en suelos desnudos(Padilla y Pugnaire 2006, Urretavizcaya et al 2017). En proyectos de restauración, controlar las especies competidoras puede ser necesario para disminuir sus efectos deletéreos sobre las plantas objetivo(Jobidon et al 1998, Löf et al 1998, Dinger y Rose 2009, Maguire et al 2009).…”