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Non-native conifers have been planted widely because of their growth potential and wood quality. However, many of them have become invasive in the introduced ranges. In Chile, the initial introduction of non-native conifers helped the recovery of degraded land, but today some pine species present a high invasion risk when they are not properly managed, leading to detrimental impacts on natural ecosystems and biodiversity. Such is the case of Douglas fir (Pseudotsuga menziesii), a species listed as invasive in south-central Chile, as well as in many other countries, when it establishes beyond the original plantation range. The main goal of this research was to characterize the invasion pattern of P. menziesii within a recently-declared protected area nearby the Conguillío National Park in the Andes Cordillera. We aimed at determining the key factors that promote the invasion of P. menziesii outside the original plantations. We established five 1,000 m2 sampling transects (i.e., 100×10 m), considering two invasion conditions: (i) within the native forest and (ii) far into open scrub areas, both adjacent to P. menziesii plantations. We measured forest structure, soil nutrients, the floristic composition and pine regeneration before and after controlling the invasion within each study conditions. We found that P. menziesii density and soil nutrient availability in the soil decreased with the distance from the plantation. In addition, an increase in native species cover was found after removing pines, but also noted the ability of P. menziesii to readily re-invade the native forest after removal. These results indicate the need for continuous control of P. menziesii, especially inside the native forest at the early stages of invasion. We discuss the need for better plantation management to prevent its spread into natural areas and protect native forests from non-native conifers invasion.

Una revisión de Donoso y Navarro (2023) Silvicultura y Manejo de Bosques Nativos, ecología aplicada para la conservación de ecosistemas forestales. Editorial Universitaria. Santiago, Chile.

Abstract Stem analysis allows us to obtain an abundant amount of information on tree growth. A couple of algorithms exist to utilize section height and growth ring data for reconstructing height and age time‐series information. I evaluated two alternatives, a well‐known and a newly proposed algorithm using stem analysis data of four species, including deciduous and evergreen broadleaves and a conifer. I reconstructed height–age pairs by both algorithms. I fit height growth equations in a mixed‐effects model framework for each species, using the generated data with the respective algorithm. Comparisons considered confidence intervals of the estimated parameters, as well as regression‐based equivalence tests. Results showed that the fitted growth models obtained from both stem analysis algorithms were statistically equivalent. However, the proposed algorithm is simpler and thus provides a useful alternative to current methods. Based on the findings, I recommend using this new stem analysis algorithm to reconstruct tree height growth with stem analysis data.

Valdivian Temperate Rainforests in Chile have a global conservation value, but nowadays many correspond to secondary forests following regeneration in agricultural and burned lands, and to high-graded old-growth due to mismanagement, especially at mid to low elevations. Perspectives for increasing old-growth attributes in these productive forests through silviculture are high considering the diverse demands of ecosystem services and the high timber value of tree species. In the Llancahue experimental forest (40°S Lat) we implemented three ecological silviculture approaches: variable-density thinning in a Nothofagus dombeyi secondary forest (NDS), irregular shelterwood in a mature N. dombeyi forest (NDM), and single-tree selection cutting in a partially harvested old-growth forest (OG). Based upon an old-growth index (OGI) that includes density, basal area (BA), BA of the trees >80 cm in diameter, ba of shade-tolerant species, and the Gini coefficient, and aims to estimate how close a given forest is to a typical old-growth forest, these forests had a 22, 22, and 62% OGI before management. The OGI remained similar or declined following management, but 7–10 years after management it increased in NDS and NDM and declined in the OG (significant changes only in NDM and OG). We discuss these results considering that managed forests should target for an OGI ≈70% rather than maximum values. These managed forests contribute to halt degradation, mitigate climate change (carbon stores in the forest and in timber), and may have greater adaptive capacity to disturbances. We discuss perspectives for the potential scale-up of implementing these approaches.

Spatial patterns reveal critical features at the individual and community levels. However, how to evaluate changes in spatial characteristics remains largely unexplored. We assess spatial changes in spatial point patterns by augmenting current statistical functions and indices. We fitted functions to describe unmarked and marked (tree size) spatial patterns using data from a large-scale silvicultural experiment in southern Chile. Furthermore, we compute the mingling index to represent spatial tree diversity. We proffer the pair correlation function difference before and after treatment to detect changes in the unmarked-point pattern of trees and the semivariogram-ratio to evaluate changes in the marked-point pattern. Our research provides a quantitative assessment of a critical aspect of forest heterogeneity: changes in spatial unmarked and marked-point patterns. The proposed approach can be a powerful tool for quantifying the impacts of disturbances and silvicultural treatments on spatial patterns in forest ecosystems.

Prumnopitys andina (lleuque) es una especie de conífera con una distribución restringida en Chile y Argentina. A pesar de su importancia ecológica, los conocimientos sobre la estructura y dinámica de los bosques donde crece P. andina son limitados. El objetivo de este trabajo fue describir la estructura y regeneración de bosques con alta presencia de P. andina. Se muestrearon bosques cercanos a Lonquimay (38°1' S, 71.3 O – 38°3'S, 71°3' O) midiendo árboles, regeneración y flora vascular a través de 24 parcelas. Se encontró que P. andina ocurre predominantemente en el estrato superior (15-18 m) acompañado por Nothofagus obliqua y/o Austrocedrus chilensis, además de Lomatia hirsuta y Maytenus boaria en estratos intermedios (4-8 m). En base a la estructura, se identificaron tres tipos de bosques de P. andina: bosques abiertos, bosques secundarios adultos y bosques puros. Los bosques puros de P. andina o “lleuquerías” alcanzaron áreas basales entre las más grandes reportadas para bosques templados del sur de Sudamérica (230 m2/ha). La regeneración de P. andina osciló entre 1.550 individuos/ha en bosques abiertos y 25.000 individuos/ha en bosques puros. P. andina exhibió una estrategia de regeneración aparentemente continua, y en ausencia de disturbios antrópicos como pastoreo de ganado o tala selectiva, sus poblaciones serían autosuficientes.

In this analysis, a method for construction of forest canopy three-dimensional (3D) models from terrestrial LiDAR was used for assessing the influence of structural changes on reflectance for an even-aged forest in Belgium. The necessary data were extracted by the developed method, as well as it was registered the adjacent point-clouds, and the canopy elements were classified. Based on a voxelized approach, leaf area index (LAI) and the vertical distribution of leaf area density (LAD) of the forest canopy were derived. Canopy–radiation interactions were simulated in a ray tracing environment, giving suitable illumination properties and optical attributes of the different canopy elements. Canopy structure was modified in terms of LAI and LAD for hyperspectral measurements. It was found that the effect of a 10% increase in LAI on NIR reflectance can be equal to change caused by translating 50% of leaf area from top to lower layers. As presented, changes in structure did affect vegetation indices associated with LAI and chlorophyll content. Overall, the work demonstrated the ability of terrestrial LiDAR for detailed canopy assessments and revealed the high complexity of the relationship between vertical LAD and reflectance.