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Shrub influences on seedling performance when restoring the slow‐growing conifer Pilgerodendron uviferum in southern bog forests
Forest restoration is most efficient if it can take advantage of facilitative interactions between established vegetation and planted trees. However, positive and negative interactions have been identified in a number of plant communities. After centuries of anthropogenic fires, forest recovery has been extremely slow in southern bog forests previously dominated by the slow‐growing and vulnerable conifer Pilgerodendron uviferum on Chiloé Island, Chile. Today, the landscape is dominated by secondary shrublands with scattered patches of Sphagnum moss and limited natural tree regeneration. We hypothesized that the retention of secondary shrubs facilitates the early performance of P. uviferum restoration plantings by providing better microsite conditions. To test this hypothesis, we compared the response of seedlings planted on sites prepared at two levels of intervention: after shrubs had been removed or where shrubs were retained. Shrub retention showed a nurse‐plant effect on P. uviferum seedlings 4 years after planting, which resulted in reduced physiological stress (measured as Fv/Fm) for seedlings, as well as reduced browsing. Consequently, the seedlings growing in areas with shrub retention had larger height increment and higher vitality than those in areas where shrubs had been removed. Thus, the more open micro‐site conditions created by shrub removal resulted in generally poorer seedling performance, although seedling mortality—which was low overall (approximately 2–4%)—showed no significant difference between the two levels of intervention. These findings have direct implications for the restoration of slow‐growing conifers that can tolerate extreme wet conditions in highly degraded forests.
Bannister, Jan R.-Travieso, Germán-Galindo Castillo, Nicole-Acevedo Tapia, Manuel-Puettmann, Klaus J.-Salas Eljatib, Christian
2020
Monitoreo a corto y largo plazo en ensayos de restauración de la conífera longeva y de lento crecimiento Pilgerodendron uviferum
El monitoreo a largo plazo es fundamental para comprender las respuestas a acciones de restauración en especies de lento crecimiento como la conífera nativa Pilgerodendron uviferum. Luego de incendios catastróficos, la mayoría de los árboles y semillas de esta especie fueron eliminados, restringiendo su recuperación natural. El objetivo de este estudio fue analizar las implicancias del monitoreo a corto y largo plazo en la interpretación de resultados en ensayos de restauración pasiva y activa de Pilgerodendron uviferum, posterior a incendios en la Isla de Chiloé. Durante 10 años se evaluó la producción de semillas, el reclutamiento natural, y la regeneración asistida mediante plantaciones de P. uviferum bajo diferentes condiciones de micrositio en bosque turbosos y luminosidad en bosque de mejor drenaje. La producción de semillas de P. uviferum fue irregular y abundante cada siete años (~200 semillas m-2). La regeneración natural luego de ocho años aumentó en un 80 %, principalmente en sustratos cubiertos con musgos y en asociación con Donatia fascicularis y Astelia pumilia. La abundancia de regeneración natural estuvo positivamente asociada a árboles semilleros de mayor edad, la altura y diámetro de las plantas fue favorecida por la protección arbustiva. En sitios turbosos, la plantación en camellones alcanzó mayores tasas de sobrevivencia (78 %) y en sitios con mejor drenaje, fue mayor bajo protección de dosel superior (100 %). Los resultados sugieren que especies de lento crecimiento como P. uviferum requieren de periodos prologados de monitoreo para interpretar adecuadamente los resultados de ensayos de restauración en bosques quemados.
Galindo Castillo, Nicole-Bannister, Jan R.-Laage, Katharina
Región de Los Lagos
2021
The influence of microsite conditions on early performance of planted Nothofagus nitida seedlings when restoring degraded coastal temperate rain forests
Widespread impacts of changes in land use, climate, and disturbance regimes continue to affect mature forests and their subsequent post-disturbance recovery. In South American temperate rainforests, the recovery of the original composition, structure, and ecological services of now-degraded old-growth forests is additionally hampered by the aggressive competition that the native Chusquea bamboo understory exerts on juvenile trees, thus arresting ecological succession. In this study, we aim to evaluate the early performance of Nothofagus nitida seedlings (pioneer tree species that tolerate shade) planted beneath nurse canopy following removal of the understory, and to define which microsite conditions can facilitate N. nitida growth. For this, we monitored 45 N. nitida plantings established in 2014 in Chiloé Island (North Patagonia, Chile) for five years. After this period, planted seedlings presented relatively good indicators of performance with low mortality (~30% of dead seedlings), good vitality (~60% of healthy seedlings), and relatively high mean periodic annual increments in root collar diameter and height (~1.7 mm/year and ~17.4 cm/year, respectively). Furthermore, our results show that the planted N. nitida seedlings can tolerate and grow under low-light conditions, though their diameter and height increase significantly with higher light availability. However, physiological stress of planted seedlings increased in open areas with more available light and planted seedlings were most stressed during the summer season. Increased summer-season stress was attributed to the months with highest depth of the water table, highest maximum and mean photosynthetic active radiation (PAR) values, highest temperature, and lowest precipitation. Our results show for first time with field-based data that different microsite and canopy conditions facilitate the initial performance of N. nitida plantings after removal of the Chusquea bamboo understory. In this context, we conclude that the removal of the Chusquea bamboo understory is the key to overcome arrested succession of coastal temperate rain forests Furthermore, supplementary planting of pioneer tree species that tolerate shade, like N. nitida, assists natural forest recovery, especially in humid and open sites with some protection of a nurse canopy.
Bannister, Jan R.-Acevedo Tapia, Manuel-Travieso, Germán-Holz, Andrés-Galindo Castillo, Nicole
Región de Los Lagos
2021

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