Phytochemical Screening and Antioxidant Activity of Seven Native Species Growing in the Forests of Southern Chilean Patagonia

The genus Nothofagus is one of the most abundant in the subantarctic Patagonian forests. Five species inhabit these ecosystems, three evergreen (Nothofagus betuloides, Nothofagus dombeyi, and Nothofagus nitida) and two deciduous (Nothofagus pumilio and Nothofagus antarctica). This is the first report on the levels of secondary metabolites and the antioxidant capacity of Patagonian tree species growing in natural environments. The aim of this work was to carry out a phytochemical screening, to determine the antioxidant capacity, the sun protection factor, and the α-glucosidase and tyrosinase inhibitory activity of foliar extracts of the five previous species. Besides, Aristotelia chilensis and Berberis microphylla, two species of Patagonian shrubs growing in the same forests, were used as reference. N. dombeyi was the Nothofagus with the best antioxidant capacity. B. microphylla differed from all studied species. Moreover, the Nothofagus was split into two groups. N. betuloides and N. dombeyi are the most similar species to A. chilensis. The α-glucosidase was completely inhibited by all studied extracts. Furthermore, N. antarctica, N.pumilio, and N. nitida inhibited about 70% of the tyrosinase activity. All the results found in this study for the species of the genus Nothofagus support further research on their potential beneficial properties for human health.

Quantifying Biochemical Traits over the Patagonian Sub-Antarctic Forests and Their Relation to Multispectral Vegetation Indices

The effects and consequences of global warming on the productivity of the Patagonian forest are still unknown. The use of Unmanned Aerial Vehicles (UAV) promotes new knowledge of the most pristine and unknown sub-antarctic forests located in Chilean Patagonia. This work presents an initial approach to spatialize biochemicals over the Patagonian forests using ultra-high spatial resolution imagery acquired from UAVs equipped with a multispectral (visible, near-infrared, and thermal) sensor. The images were obtained in multiple flights over the Cerro Castillo National Park (Aysén Region, Chile), and several Vegetation Indices (VIs) were estimated. Leaves of Nothofagus pumilio (Poepp. et Endl.) Krasser (Nothofagaceae) individuals were extracted after the flights and were then used to determine the biochemicals traits of chlorophylls (Chl-a and Chl-b) and carotenoids pigments, as well as the total phenolic content (TPC), total flavonoids content (TFC), and the DPPH radical scavenging assay. Their relationships with multiple VIs was analyzed in order to assess the spatiality of the biochemicals traits in the forest during it most productive phenological stage. Results showed high correlations for the biochemical traits pigments (R2 > 0.75) with the indices DVI, MCARI, and MSAVI1 as the best performing indices, while further spectral availability is needed for significant correlations with biochemicals traits related to the antioxidant capacity. Spatialization of the biochemical traits within UAV imagery was also performed evaluating their representation in the forest. This work allowed us to identify the different spectral behavior of the N. pumilio species, its relation to biochemical traits, and their spatialization, thus presenting the first step to developing a monitoring protocol for the evaluation of the Patagonian forests under the current global warming scenarios in the region.

Landscape Variables Influence over Active Restoration Strategies of Nothofagus Forests Degraded by Invasive Castor canadensis in Tierra del Fuego

North American beavers (Castor canadensis) are responsible for the major changes in the Tierra del Fuego Archipelago, altering riparian forests for the long-term. Passive restoration of the areas affected was ineffective in the medium-term (up to 20 years), being necessary active strategies. Plantations in abandoned ponds were made with Nothofagus pumilio and N. antarctica tree species across Tierra del Fuego island (Argentina). In the first experiment, we analysed the influence of biotic and abiotic factors in three micro-habitats in the impacted areas: front and tail of ponds, and cut not-flooded forest areas. Five-years-old N. pumilio seedlings had 39% survival in front, 21% in tails, and 46% in cut areas at year-3 of the restoration experiments, being negatively influenced by plant cover and soil moisture. Lower growth was recorded during year-1 (0.7–0.9 cm yr−1), but increased on time (1.9 cm yr−1 front, 1.6 cm yr−1 tail, 4.3 cm yr−1 cut areas). A second experiment explores the alternative to substitute the tree species to face the harder conditions of the impact and climate change. For this, we conducted a new plantation at four locations across the main bioclimatic zones, where 10–40 cm N. antarctica plants attained 17% survival in meadows (front and tail) and 30% in cut areas, being higher with larger than smaller plants (25% vs. 18%), and where they are mainly influenced by rainfall (4% in sites <400 mm yr−1 and 41% in >400 mm yr−1). The main damage was detected in the above-ground biomass due to dryness, but root survival allowed the emergence of new shoots in the following growing season. It is necessary to monitor different Nothofagus species across natural environments in the landscape to determine the feasibility and effectiveness of different strategies in restoration plans, considering the selection of climate-resilient tree species.

Functional ecology of Nothofagus pumilio regeneration in relation to light availability = Ecología funcional de la regeneración de lenga (Nothofagus pumilio) respecto a la disponibilidad de luz

Las propuestas silvícolas de los bosques de Nothofagus pumilio se basan en la apertura del dosel para estimular el crecimiento de la regeneración, cambiando la disponibilidad de agua y luz. Las plántulas sobreviven como si fueran especies tolerantes y crecen lentamente por largo tiempo (más de 20 años) bajo altas coberturas. Sin embargo, cuando el dosel se abre debido a la cosecha o volteos por viento, la regeneración reacciona como una especie intolerante, colonizando rápidamente los sectores abiertos. El objetivo del estudio fue efectuar una comparación, analizando las características fisiológicas y morfológicas de plántulas de N. pumilio creciendo en un gradiente de luz bajo condiciones controladas de riego y temperatura.