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Development of 26-year-old mixed forests following different regeneration cutting treatments in Andean temperate rainforests of south-central Chile
Tree regeneration following even-aged silvicultural methods in the evergreen forest type (EFT) has been scarcely studied in Chile, although this is the largest forest type in a region of highly productive native forests. In 1981/1982 a total of nine 1.44-ha experimental units with old-growth forests of the EFT were subjected to block clearcutting (BCC), strip clearcutting (SCC) and reserve shelterwood cutting (RSC) methods (three replicates in each case) in the Andes range in south-central Chile (41°35′S–72°35′W). The resulting second-growth forest stands following these cuttings were evaluated in terms of composition, density, basal area, mean diameter and height after four and 26 years (432 4 m2 plots in 1986, and 78 100 m2 plots in 2008). Four years after cutting, there were >one million tree seedlings per hectare in more than 10 species. In all experimental units one shade-tolerant species (Amomyrtus luma), one midtolerant species (Eucryphia cordifolia) and two very shade-intolerant species (Embothrium coccineum and Weinmannia trichosperma) comprised between 69 and 74% of the total density. The SCC favored a greater relative dominance of all the more shade-tolerant species, and the BCC treatment was more favorable for pioneer species (in addition to E. coccineum and W. trichosperma also Drimys winteri, Caldcluvia paniculata and Nothofagus nitida). At age 26, the short-lived E. coccineum dominated in all treatments, and its major coexisting species in terms of tree density were the midtolerants D. winteri, Eucryphia cordifolia and N. nitida, and the shade-tolerants Laureliopsis philippiana and A. luma. However, the BCC significantly favored the development of N. nitida and D. winteri (three times more basal area than in the other treatments), which might be explained by increasing soil moisture that occurs in this region following this type of disturbances. While these treatments did not show significant differences in mean diameters and dominant height, the BCC and SCC treatments allowed denser, diverse and well-stocked second-growth forests compared to the RSC method, illustrating the differences between truly even-aged and two-aged silvicultural methods upon these variables. Overall, these forests show a high resilience, rapid reorganization and high productivity following the application of even-aged silvicultural methods.
Donoso, Pablo J.-Schlegel Heldt, Bastienne-Salas Eljatib, Christian-Donoso, Claudio
2019
Western conifer seed bug (Leptoglossus occidentalis) challenging stone pine cropping in the Southern Hemisphere
Stone pine edible seeds are highly appreciated and increasingly demanded. However, kernel yield (percentage of total weight corresponding to kernel) has halved in European producing countries largely due to the attack of the invasive seed-feeding insect Leptoglossus occidentalis. In the Southern Hemisphere, where new stone pine plantations have shown positive results in terms of growth, cone production and health, the exotic seed pest L. occidentalis was first detected in 2017 in Chile, with observed changes and damages having been subsequently reported. The objective of this study was to assess cone and seed traits, and kernel-per-cone yield in P. pinea in Chile before and after the detection of the regional presence of L. occidentalis in 2017. Cone, seed and kernel traits were assessed in seven plantations from central Chile from 2010 to 2015 (before L. occidentalis arrival) and from 2018 to 2019 (after the pest arrival). For the kernels, three types of insect damage were quantified: type I (endosperm/embryo damage), type II (endosperm elimination) and type III (empty seeds). Results showed an average kernel yield of 4.0 ± 0.1%, with no differences between periods. However, in Mulchén, a significant decrease was recorded in cone weight, seed weight and kernels per cone. Regarding kernel analysis, significant increases in damage types I and II were found in all plantations after 2017. Cone assignment to weight categories showed that type I (partially damaged kernel) was the most frequent (58.6%) damage in heavy cones (>550 g), and damage type II was frequent in cones of <350 g in weight (51.4%). Thus, it is necessary to monitor the advance of the insect and its effects on stone pine cropping in non-native habitats. Given that in the southern area of Latin America stone pine is grown in managed plantations, biological and/or chemical control might be applied to limit the negative impact of L. occidentalis.
Loewe Muñoz, Verónica-Delard R., Claudia-Del Río, Rodrigo-Balzarini, Mónica
2021
Irrigation and fertilization as tools to boost growth stability of stone pine (Pinus pinea L.) plantations
Pinus pinea es una especie mediterránea que crece y se desarrolla vigorosamente en Chile. Esta especie es resistente a la sequía; sin embargo, se ha encontrado que es sensible al aumento de la aridez. Pocos estudios han reportado efectos del riego y de la fertilización en el crecimiento, pero no hay estudios detallados que consideren los efectos de ambas técnicas de manejo para mejorar la estabilidad del crecimiento. En este trabajo, las variaciones diarias del diámetro del tronco (SDV) en Pinus pinea se monitorearon durante todo un año de crecimiento utilizando dendrómetros digitales en una plantación de 31 años en Chile. Se evaluaron cuatro prácticas de manejo como herramientas para estimular el crecimiento: fertilización, riego, su combinación y control. Las series de crecimiento diario mostraron una marcada sincronía entre árboles de diferentes esquemas de manejo. El tratamiento combinado (fertilización y riego) resultó en un período de crecimiento un 25% más largo y un mayor crecimiento que el control. Durante el período de crecimiento más rápido del tronco, los incrementos diarios de diámetro fueron, en promedio, 0.06 mm para árboles fertilizados y regados, y 0.02 mm para árboles del control. Se encontraron correlaciones significativas entre los SDV estandarizados y series de variables climáticas, evidenciando que los árboles no tratados tenían la mayor sensibilidad a temperaturas extremas, lluvia y evapotranspiración potencial. La variabilidad en el crecimiento diario del diámetro del tronco de los árboles fertilizados y regados se correlacionó solo con la temperatura mínima. Los resultados resaltan la importancia de la fertilización y del riego en plantaciones de Pinus pinea para mejorar el crecimiento del diámetro y reducir la variabilidad causada por la sensibilidad a las condiciones ambientales.
Loewe Muñoz, Verónica-Del Río, Rodrigo-Delard R., Claudia-Balzarini, Mónica
2020
Climate response and drought resilience of Nothofagus obliqua secondary forests across a latitudinal gradient in south-central Chile
The climate response and resilience of tree growth to drought events have been widely reported for forests from the Northern Hemisphere. However, studies are much scarcer in the extra-tropical forests of southern South America. Mediterranean and Temperate forests of Chile are suffering from a moderate warming and a sustained precipitation decrease, occurring on top of an unprecedented megadrought since 2010. This study evaluated tree-growth patterns, the climate response and drought resilience of nine secondary Nothofagus obliqua forests across a latitudinal gradient from Mediterranean to Temperate climate in the Andes of Chile (35.7° to 40.3° S). Moreover, to improve the understanding of the spatial variation in productivity patterns, this research assessed trends in the maximum Normalized Difference Vegetation Index (peak in the NDVI) across the gradient for 2001–2018. Tree-growth patterns were highly influenced by stand dynamics, with steep decreasing trends in most of the stands related to a gradual canopy closure. Productivity trends had a flat pattern north of 38oS, but positive trends south of this latitude, which were mostly attributed to stand development. Tree growth was positively related to precipitation in all the sites, with annual and summer rainfall being more important in the north (Mediterranean climate) and south (Temperate climate), respectively. Conversely, maximum temperature had a negative effect on growth in most of the studied forests. This implies that projected warmer and drier conditions may have a detrimental effect on N. obliqua growth during coming decades. The two northern stands, located at the species dry range edge, were among the most resilient to drought and have not been strongly affected by the current megadrought in the area. Overall climate conditions, however, do not define the tolerance of stands to droughts, likely because local environmental and forests conditions play a key role. Although droughts have not strongly impacted the growth of N. obliqua across its distribution so far, future studies should assess the effects of the current long-term megadrought on growth resilience, and physiological studies should address the impacts of droughts and heat waves on forest function beyond what growth can unveil.
Urrutia-Jalabert, Rocío-Barichivich Henríquez, Jonathan Eligio-Rozas, V.-Lara Aguilar, Antonio-Rojas Ponce, Yasna-Bahamóndez V., Carlos-Rojas-Badilla, Moisés-Gipoulou-Zuñiga, T.-Cuq, Emilio
2021
Financing energy efficiency retrofits in Chilean households: the role of financial instruments, savings and uncertainty in energy transition
High firewood consumption for heating produces high levels of pollution in cities in centraland southern Chile, with serious consequences for health and quality of life. Energy effi-ciency measures (EEMs) have been identified as the best strategy to reduce air pollutionand maximize social benefits. However, their adoption has been slow. The objective of thisarticle is to investigate household preferences for financial incentives needed to promoteprivate investments in EEMs in Central-Southern Chilean households and study the role ofenergy savings and the uncertainty about potential savings in the investment decision, withthe aim of finding solutions to increase the adoption of these technologies. We use a choiceexperiment to explore the trade-off between the investment costs, financial instruments,energy savings, and the uncertainty about achieving the theoretical savings provided byengineering and architectural models. The results show that financial instruments playthe most important role in this decision, followed by the savings achieved by the retrofit.Householders prefer to finance their investments with a mix of their personal resources andmedium-term credits, trying to avoid long-term commitments. Although uncertainty wasfound to be a significant variable, it seems to play a small role in the investment decision.
Schueftan, Alejandra-Aravena, Claudia-Reyes Gallardo, René
2021
Restoring native forests from Pinus radiata plantations: Effects of different harvesting treatments on the performance of planted seedlings of temperate tree species in central Chile
Extensive areas of native vegetation have been cleared to establish commercial exotic tree plantations in south-central Chile, a region known as a world biodiversity hotspot. Despite increasing societal demands to restore native forests in parts of the landscape, documented experiences for this form of restoration are lacking. We conducted a landscape-replicated experiment to test the influence of different harvesting treatments (clearcut, strip-cutting and unharvested control) on the early establishment of native tree species in 20-year-old Pinus radiata plantations. Group plantings of shade-intolerant (Nothofagus dombeyi; Nothofagus obliqua), semi-tolerant (Nothofagus alpina; Laurelia sempervirens) and shade–tolerant species (Aextoxicon punctatum; Cryptocarya alba) were established across the treatments, and seedling performance and water status were monitored during the first two growing seasons. Mean survival was significantly higher in the strip-cuttings (77%) and control (70%) than in the clearcuts (38%), while mean height and root collar diameter growth were significantly higher in the strip-cuttings (16 cm year−1; 0.2 cm year−1) and clearcuts (16 cm year−1; 0.2 cm year−1) than in the control (5 cm year−1; 0.1 cm year−1). Shade-intolerant and semi-tolerant species showed the highest growth responses to openings. Leaf water potential was significantly higher in seedlings in the strip-cuttings than those in the control and clearcuts, and stomatal conductance was significantly higher in the strip-cuttings and clearcuts than in the control. Higher seedling performances and lower water stress in the strip-cutting treatment suggest that partial canopy removal is a suitable method for artificial regeneration of native tree species with different shade tolerances for native forest restoration from P. radiata plantations.
Kremer, Klaus-Bannister, Jan R.-Bauhus, Jurgüen
2021
Effect of thinning on growth and shape of Castanea sativa adult tree plantations for timber production in Chile
Chestnut (Castanea sativa Mill.) is an interesting species for high-quality timber production. It is well known that the species responds to early thinning, but there is no information on the impact of late interventions. The objective of this study was to assess the effect of a late thinning on the performance of unmanaged adult chestnut plantations in Chile. Future-tree selective thinning and control were compared in adult plantations using a randomized complete block design with three replicates at three sites, Minas, Pillo-Pillo and Pumillahue. Tree growth was evaluated periodically during the first 7 years after thinning in all plantations. Additionally, almost 20 years after the intervention, the Pumillahue plantation was measured for growth and tree shape variables. In this case study, the effect of thinning on tree growth decreased considerably after 5 years, with a maximum DBH increment in the third year after the intervention (45.8 %, 68.6 %, and 42.2 % in Minas, Pillo-Pillo and Pumillahue, respectively). In all plantations, basal area was smaller in the thinned plots in the first years after the intervention, but in Pumillahue, 19 years after thinning, no differences were found among treatments. Height was statistically greater under thinning seven years after the intervention; this effect was also found in Pumillahue plantation 19 years after thinning. Most trees showed high vigor, and were straight and healthy, even in control plots. Late effect of thinning was observed 19 years after thinning on tree shape, with a reduction in the proportion of bifurcated trees from 16 % to 8 %. The results suggest that late thinning is an effective silvicultural intervention to produce high-quality chestnut timber in unmanaged adult plantations. Progressive and frequent thinning should be used to increase growth and improve timber production in chestnut.
Benedetti Ruiz, Susana-Loewe Muñoz, Verónica-Del Río, Rodrigo-Delard R., Claudia-Barrales M., Luis-Balzarini, Mónica
2023
Relationships among livestock, structure, and regeneration in Chilean Austral Macrozone temperate forests
A Macrozone is a socioecological region with shared geographic and demographic characteristics. Within the Chilean Austral Macrozone (43° to 56° SL), the native temperate forests serve as a crucial resource, offering multiple ecosystem services to local communities. These forests significantly support animal husbandry practices involving cattle, horses and sheep. However, introducing these exotic species affects natural regeneration and compromises their long-term sustainability. This study proposes a new classification of the temperate forests in the Chilean Austral Macrozone based on structure parameters and determine their relationships with animal husbandry and natural regeneration. Data were obtained from Chile's National Forest Inventory (NFI) (2001–2010), including 195 inventory plots (500 m2) with 21 tree species. We redefined the forest categories described in NFI according to the proportional basal area of each tree species at each plot. We used two levels of analysis: forest composition (Level 1), which includes general categories such as mono-specific (dominated by a single tree species), bi-specific (dominated by two tree species), and multi-specific forests (dominated by multiple tree species), and forest type (Level 2), which includes specific species (e.g., Nothofagus pumilio) or species groups (e.g., N. pumilio - N. dombeyi) with economic relevance. We evaluated the data using univariate and multivariate analyses. We found 18 forest types in the Austral Macrozone, in contrast to the three traditionally recognized forest types used in the NFI (e.g., lenga, evergreen, coihue de Magallanes). Livestock was observed in all forest types, where Nothofagus forests showed that regeneration in N. antarctica and N. pumilio were higher with livestock than without livestock breeding (Hedges' g > 0.51). The natural regeneration of the studied forests was influenced by animal husbandry, environmental variables (bioclimatic and topographic factors), and forest structure. Our data suggested the importance of using more forest types than the three classics to generate tools or recommendations that are more focused on the particularities of each one. The classification must be based on forest parameters obtained during NFI. The proposed forest type classification reflects the complexity and richness of the forests in a better way, which could improve forest management and the development of public policies related to climate change and sustainability. Finally, although livestock pressure was observed in all forest types, the impact over some areas (e.g., N. antarctica) needs special attention in the forest management and conservation planning for the Chilean Austral Macrozone.
Huertas Herrera, Alejandro-Toro Manríquez, Mónica-Salinas S., Jaime-Rivas Guíñez, Fernanda-Lencinas, María Vanessa-Martínez Pastur, Guillermo
2023
Linnean and Wallacean shortfalls in the knowledge of arthropod species in Chile: Challenges and implications for regional conservation
Despite global efforts to identify and classify species to improve biodiversity baselines, there still remains large knowledge shortfalls that affect our understanding of the functioning of ecosystems and the design of effective conservation practices. Using the results of the first ongoing large-scale biodiversity inventory for Chile which has already recorded ca. 1,800 species and discovered 87 new species of arthropods, we explore and discuss taxonomy (Linnean) and distribution (Wallacean) shortfalls that preclude large-scale knowledge of arthropod biodiversity for one of the lesser studied groups in the world — the arthropods. Linnean shortfalls are mainly associated with the lack of funding of monitoring and inventory initiatives and the bias towards most charismatic or umbrella species, which in turn trigger effects on the experts’ availability, recruitment of taxonomists in research centers, journal impact factors, as well as the availability of scientific collections of type specimens. Instead, Wallacean shortfalls are related to accessibility to remote areas, and the spatial and temporal resolution of sampling efforts. Based on our results and literature review, we discuss the findings and also propose a novel conceptual framework aimed to reduce data gaps and support biodiversity conservation policies, particularly in developing countries. The framework has three main components: (1) the ecosystems, their species, and the threats; (2) the key elements for a biodiversity assessment strategy, and (3) an action plan for protecting biodiversity.
Vergara Asenjo, Gerardo-Alfaro, Fermín M.-Pizarro Araya, Jaime
2023
+A 5680-year tree-ring temperature record for southern South America
It is widely documented that the Earth’s surface temperatures have increased in recent decades. However, temperature increment patterns are not uniform around the globe, showing different or even contrasting trends. Here we present a mean maximum summer temperature record, based on tree-ring widths, over the past 5682 years (3672BC – 2009AD) for southern South America (SSA), covering from mid-Holocene to the present. This is the longest such record for the Southern Hemisphere (SH), and expands available annual proxy climate records for this region in more than 2060 years. Our record explains 49% of the temperature variation, and documents two major warm periods between 3140–2800BC and 70BC – 150AD, which coincide with the lack of evidence of glacier advances in SSA. Recent decades in the reconstruction (1959–2009) show a warming trend that is not exceptional in the context of the last five millennia. The long-term relationship between our temperature reconstruction and a reconstructed total solar irradiance record, with coinciding cycles at 293, 372, 432–434, 512 and 746 years, indicate a persistent influence of solar forcing on centennial climate variability in SSA. At interannual to interdecadal scales, reconstructed temperature is mainly related to the internal climate variability of the Pacific Ocean, including El Niño Southern Oscillation (ENSO) and longer oscillations. Our study reveals the need to characterize regional-scale climate variability and its drivers, which in the context of global-scale processes such as anthropogenic warming, interact to modulate local climate affecting humans and ecosystems.
Lara Aguilar, Antonio-Villalba, Ricardo-Urrutia-Jalabert, Rocío-Gonzalez Reyes, Alvaro-Aravena, Juan-Luckman, Brian-Cuq, Emilio-Rodríguez, Carmen Gloria-Wolodarsky-Franke, Alexia
2020

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