Revista Bosque

Ecological silviculture: a model for plantations of species of the genus Nothofagus in Chile

2024-08-11T02:08:54+00:00

Commercial forest plantations grow wood and fiber in an efficient manner. These plantations are generally monospecific, grown in short rotations, and clear cut. In many countries, including Chile, these plantations are established with exotic species. Although these plantations will continue expanding in the world, there are also increasing social and ecological demands to establish, or generate, plantations with greater diversity. Ecological silviculture looks after the development of these types of forests that provide timber and multiple ecosystem services, with an emphasis in developing complex and adaptive ecosystems. This article provides ecological silviculture proposals for plantations with Nothofagus dombeyi and Nothofagus alpina. We discuss the conventional model of relatively short rotations and alternative models leading to muti-aged forests that will require supplementary plantations with species of the genus Nothofagus. This model is not meant to discard the conventional plantations, but rather to be present in landscapes with productive purposes, safeguarding diverse ecosystem services in forests with greater adaptive capacity.

Preliminary experience in age dating with dendrochronological techniques in the olive tree (Olea europaea). Comunidad de Campos de Jahuel, commune of Santa María, Valparaiso, Chile

2023-11-10T13:37:00+00:00

Dendrochronology is a recognized discipline for the study of chronologies and the evaluation of long-term environmental changes. In Chile, using dendrochronological techniques, different tree species have been studied with excellent results. However, there are still species for which we do not know their dendrochronological potential, as is the case of Olivo. The interest of the Campos de Jahuel community in knowing the age of their olive trees and the exact time when they were introduced in the valley, opened the door for an exploratory study of this species with the use of dendrochronological techniques. From a sampling of 15 specimens and the macroscopic analysis of the growth rings, ages of at least 200 years of antiquity were given. This experience was not without methodological difficulties considering the growth characteristics of the olive tree.

Proposals for ecological restoration in riparian areas of the humid tropics of Mexico

2024-08-10T21:02:26+00:00

Tropical riparian vegetation is critical because of the different levels of disturbance caused by various anthropogenic activities. The objective of this study was to generate proposals for ecological restoration in riparian areas with different levels of disturbance. The proposals were generated from a previous study on sites and reviews of specialized scientific literature. Active and passive restoration strategies were also considered. The proposals consisted mainly of nucleation and linear methods, considering three combinations of species with different stages of succession: a) tree species of early succession with species tolerant to intermediate shade, b) sticks with the capacity for vegetative reproduction with species of intermediate succession, and c) shrubby species with species of intermediate succession. Thirteen restoration proposals were generated, of which five corresponded to nucleation and three linearly as part of the active restoration. On the other hand, five proposals focused on passive restoration. The implementation of these strategies can be adapted using local riparian species, considering their light and shade requirements as well as their adaptation to edaphic conditions.

Morphological variation in cones and seeds of two species of pinyon pines distributed in a latitudinal gradient of Mexican highlands

2024-01-16T15:08:31+00:00

Intra and interpopulation variation of cones and seeds of Pinus cembroides and P. johannis from central Mexico was analyzed. Objectives: to identify cone and seed variation in two pinyon species; to corroborate taxa-specific identity according to cone and seed characteristics; and to detect genetic interaction between species. Cones and seeds were collected from 27 populations distributed in the Mexican Altiplano. Cone length and width, peduncle length, cone umbos length, number of scales, seed length and width, and testa thickness were measured. With the morphological characters, by population and between species, a univariate analysis was performed. Intra-population differences were analyzed with the Kruskal-Wallis test and interspecific differences with the t-test. Discriminant analysis was used to evaluate genetic interaction between species. Cone and seed morphometry between species showed significant differences in cone length and width, umbo length and seed length. P. johannis showed greater peduncle length and seed testa thickness. Discriminant analysis differentiated the two species and evidenced the eventual hybridization between them. The structures measured in populations of P. cembroides and P. johannis from the center of distribution had intermediate dimensions compared to northern or southern populations. The cones and seeds of P. cembroides were less variable than those of P. johannis in relation to latitudinal distribution. The information is considered useful for forest management and conservation of specific populations.

Physical and mechanical wood properties of Eucalyptus globulus (Argentina), and its association with site quality and plantation age

2024-09-02T00:06:50+00:00

The aim of this work was to study the physical and mechanical properties of Eucalyptus globulus wood from Buenos Aires (Argentina) and relate them to the site quality and planting age. 23 trees from 10 to 15 years old and with site index from 20.9 m to 34.4 m in height were sampled, which were sawn to obtain specimens. Physical properties (density, percentage of heartwood in relation to the area of the section, dimensional changes) and mechanical properties (static bending, hardness, and penetration resistance) were determined. The results showed that, regardless of the site or age, the wood had an average density of 699 ± 57 kg m-³, a heartwood percentage of 54 ± 8 %, an anisotropy coefficient of 1.6 ± 0.2, and elastic modulus of 10,934 ± 3,034 MPa, modulus of rupture of 100.07 ± 16.97 MPa and Brinell hardness of 2.7 ± 0.7 kN mm-². These values suggest that wood is suitable for good-quality sawn products, both for solid and reconstituted uses. The indices from higher sites produced wood with greater dimensional stability associated with lower anisotropy coefficients, without being associated with changes in density, heartwood content, and mechanical properties. Planting age only influenced heartwood content; older trees recorded higher heartwood content. The evaluated physical-mechanical properties were not correlated with growth parameters. A high correlation was observed between the penetration resistance with respect to the density and hardness and between the density and modulus of elasticity.

Variation in seed vigor of Pinus cembroides collected in stands in Nuevo León and Veracruz states in Mexico

2024-09-01T23:39:36+00:00

Seeds of Pinus cembroides lose vigor and viability owing to the effects of high humidity and high temperature, which damage the cell membranes. The objective of this study was to evaluate the vigor of Pinus cembroides seeds using an aging test. Seeds were collected from the municipalities of Galeana, Nuevo León, and Jalacingo, Veracruz, Mexico. In the aging test, the seeds were exposed to temperatures of 19, 40, 42, and 45 °C for 24, 48, 72, and 96 h. In the control, the seeds were not subjected to any treatment. In the germination test, the seeds were placed in a randomized block design with a factorial arrangement. Significant differences (P < 0.05) were found between provenances, temperatures, and periods for the percentage of germination and aging index. The percentage of germination varied between 0 % for seeds from Jalacingo exposed to 19 °C and 40 °C and 31 % for seeds in the control. The percentage of germination varied from 1 % to 84 % for Galeana seeds at 45 °C and the control, respectively. The aging index varied between 0 for seeds from both provenances in the control treatment and 1 for seeds from Jalacingo exposed to 19 °C and 40 °C. Deterioration of Pinus cembroides seeds might be due to damage to the cell membrane. The vigor of Pinus cembroides seeds was reduced because of high temperature and aging periods, which was reflected in low percentages of seed germination.

Potential distribution of Cedrela odorata and cost analysis of seed conservation of populations vulnerable to climate change in Mexico

2024-08-10T23:14:59+00:00

Climate change (CC) affects many forest species that have social and environmental benefits; therefore, it is necessary to implement conservation measures. The potential distribution of Cedrela odorata was evaluated under climate change scenarios, and the costs of seed conservation for vulnerable populations (PV) in a seed bank (BS) were analyzed. The potential distribution of C. odorata was modeled according to the GISS-E2-1-G model (from NASA’s Goddard Institute for Space Studies (GISS)), from phase 6 of the Intergovernmental Panel on Climate Change (IPCC) coupled model intercomparison project. Using the collection cost method, the costs of collecting and storing PV seeds were estimated under CC scenarios. The current value of a stored accession is 15 times greater (USD 767.61) than the market price (USD 51.0). Considering a nominal interest rate of 8.24 % for the year 2050, the cost of an accession will be almost 8.5 times more (USD 6,510.61) than its present value or almost 130 times more than its current market price. The conservation of seeds from vulnerable populations in a BS guarantees their conservation; therefore, the maintenance and operation costs of the BS will always be lower than the benefits that can be obtained. This work is important for the conservation of germplasm from vulnerable populations in a BS and represents a strategic investment owing to the economic value and environmental importance of the species.

Assessment of the Risk to Ecosystem Services for Freshwater Regulation and Provision in Isla Grande de Chiloé, Chile, due to Climate Change

2024-06-21T16:25:43+00:00

The freshwater availability of Chiloé Island is threatened by a probable decrease in precipitation in the XXI century. Therefore, preserving ecosystem services, particularly those linked to water provision and regulation, is crucial for local human development. One study sought to gauge the risk of these services by considering the ecosystem structure, processes, and human pressures. Employing the risk analytical framework, this study utilized an impact chain and a fuzzy logic tool. This study revealed that 37.5 % of the area faced high risk, 36.4 % medium risk, and 26.1 % low risk. Notably, high-risk concentrations were identified in regions with increased human intervention in the island’s northern region. These outcomes underscore the urgency to implement public policies that embrace nature-based solutions to conserve and restore Ecosystem Services. Such strategies aim to ensure efficient adaptation to climate change, while respecting the island’s local biodiversity.

Analysis of the chain value of wild edible mushrooms in the mountain area of the province of Chubut, Patagonia, Argentina

2024-08-11T01:09:21+00:00

Edible mushrooms have gained special interest in recent decades because of their value as functional foods and potential for the development of local economies. In the forested area of Chubut mountain range, various species of edible wild mushrooms proliferate, indicating the economic value of Morchella spp. and Suillus luteus. Through a survey of products, a structured survey and open interviews aimed at different actors, this study analyzed, in the tourist towns Esquel and Trevelin, the chain value of the collected species and the presence in stores of these and others cultivated such as Pleurotus spp., Lentinula edodes and Agaricus bisporus, The results showed that 76.3 % of the businesses surveyed offer products related to edible mushrooms, mainly S. luteus with local added value and competition from products made in other regions. In the case of Morchella spp., a lower local added value and a consumption and secondary processing market developed in Europe were observed. The other species had a lower presence and diversity of products, with the exception of Agaricus bisporus, which was not produced in the region. The beginning of the chain is an informal activity carried out regularly by many collectors, which concentrates on a few actors towards the end. Consumption is not completely natural. The findings indicate that there are opportunities to diversify the production of the local agri-food market, assuming a sustainable collection scheme accompanied by policies to expand demand and support for intermediate and initial actors in the chain.

Cutting propagation technique of mahogany (Swietenia macrophylla) in microtunnels from the Peruvian Amazon

2024-09-13T15:37:43+00:00

Swietenia macrophylla is a forest species of great commercial value that is categorized as vulnerable in Peru. Therefore, the objective of this study was to optimize a protocol for cutting propagation of S. macrophylla using microtunnels in the San Martín, Peruvian Amazon. Three experiments were conducted: sterilization, which tested ethyl alcohol (EA), Tween-80 (T), carbendazim (CZ), and combinations; a rooting experiment with different substrates and doses of indole-3-butyric acid (IBA); and an acclimation experiment of rooted cuttings, with different shade coverage and relative humidity conditions. The lowest contamination of S. macrophylla cuttings (9.75 %) was achieved with the combined EA-CZ treatment; this treatment resulted in the lowest necrosis (9.1 %) and survival of