Revista Bosque

Análisis de la regeneración y piso forestal dos años después en rodal incendiado del sur de México

2023-09-01T15:08:41+00:00

Temperate pine-oak forests provide multiple ecosystem goods and services; however, they are exposed to a great diversity of natural disturbances, such as forest fires. The objective was to determine the post-fire effect on the residual structure, regeneration and forest floor. In the year 2022, 12 sites were established using selected sampling in three areas with different fire severity conditions (high, medium and low). The inventory of tree and forest floor was carried out to determine the aboveground biomass, the coordinates (X, Y) of natural regeneration were recorded to determine its spatial distribution. The severity levels were differentiated using the generalized linear model and comparison of means (Duncan, 0,05). Aboveground biomass accumulation (humus and litter) and soil specific gravity) did not show significant differences (P > 0,05) between severity levels (978,26 t ha^-1). Sites with high levels of severity have a greater accumulation of necromass (287,91 t ha^-1), which makes it difficult to establish natural regeneration. The best-preserved residual tree structure of the burned stand was found in sites with medium severity level since they accumulate biomass amounts of 134,3 t ha^-1. In the same sense, these sites with medium severity contain the highest regeneration density (1.237 plants ha^-1), which is reduced by up to 79% in sites with high severity. The distribution of regeneration corresponds to an aggregate pattern across the three levels. The forest presents contiguous positive and negative post-fire changes.

Variación genética en la respuesta de familias de Pinus patula a condiciones de sequía

2023-10-12T14:24:17+00:00

Se revela un ensayo de jardín común con árboles de 18 meses de edad de 64 familias de medios hermanos de Pinus patula para identificar variación genética en el crecimiento y supervivencia en respuesta a sequía por cuatro meses (25 de noviembre 2020 a 25 marzo 2021, invierno ). Se obtuvo un diseño en parcelas divididas con dos niveles de humedad (Riego S ₀ =40-55% y Sequía S ₁ =20-39% de humedad volumétrica) en parcelas grandes y las familias en las chicas. Al inicio y final del ensayo se prolongará la altura (AT), el diámetro de la base (DB), el número de verticilos y ramas, y se calculará la tasa absoluta (TAC) y relativa (TRC) de crecimiento en AT y DB. Se encontraron diferencias entre los niveles de humedad en el crecimiento. La supervivencia fue 71% en S ₀y 60% en S ₁ . En S ₁ la TAC en AT y DB se afectó en 52 y 38% y la TRC en 46 y 32%, con respecto a S ₀ . En S ₀ , 31.4% de las plantas formaron un verticilo y 2.1% dos, en S ₁ solo 13.4% y 0.2% lo hicieron. El control genético fue moderado en los ambientes en conjunto con h ²_i entre 0.03 y 0.17 y de h ²_f entre 0.15 y 0.53. El desempeño de las familias entre las dos condiciones de humedad fue estable (r _B de 0.71 a 1.0) en todas las variables, con mayor variación genética en S ₀ que en S ₁. Se encontró una moderadamente mejorada genéticamente en el crecimiento de las familias de Pinus patula bajo restricción hídrica.

Litterfall production and its association with environmental conditions in temperate forests of the Sierra Norte de Oaxaca, Mexico

2023-08-04T15:50:37+00:00

The litterfall that accumulates in the soil is considered as the main source of organic matter, for this reason, it is essential to elucidate the patterns of litterfall production in each region and especially with which factors it is related. The main objective of the present study was to determine the contribution of litterfall to the soil of conifers and oaks and its association with environmental, biological, and disturbance conditions in temperate forests in the highlands part of the Sierra Norte de Oaxaca, Mexico. We established sampling sites along the 1.950 to 3.250 m altitudinal gradient. At each sampling site, we sampled vegetation, collected leaf litter, and measured environmental, biological, and disturbance variables. The forests in the study area have higher litterfall production values than those reported for other world forests (mixed forest: 7,06 mg ha^-1 year^-1, oak forest: 6,33 mg ha^-1 year^-1, and coniferous forest: 4,03 mg ha^-1 year^-1). Litterfall production was related to environmental conditions, with a more significant influence on oaks (temperature and precipitation intensity). In contrast, for conifers, the intensity of disturbance (number of stumps) was the most relevant variable. Conifers presented a greater contribution of litterfall to the soil, registering production peaks at certain times of the year, while the oak trees in the study area did not present litterfall production during the rainy season.

Growth curves by dominant strata in forests in southeastern Jalisco, Mexico

2023-07-04T13:31:16+00:00

One of the most important functions that forests fulfill is their capacity to store carbon, which varies according to their floristic composition, age and population density. Some models that estimate carbon balance base their estimates on empirical growth curves. In order to provide information for these estimates, the construction of growth curves for communities within the study area, based on a dominant species, were set as objectives. Data from the National Forest and Soil Inventory (2005-2009) were used to calculate the IVI by conglomerate and from a dendrogram calculated by the Ward method, forest communities dominated by one species were formed. A growth curve per community was constructed, based on the maximum yields per hectare, recorded by the forestry technicians at the average age, the percentage increases in volume per species at different ages, obtained by trunk analysis, were attributed. 5 communities dominated by Pinus oocarpa were formed with dominances from 21.08 to 54.38 %, P. douglasiana 41.45 to 89.83 %, P. devoniana 27.53 to 63.88 %, P. leiophylla 27.53 to 89.03 % and Quercus spp. 36.05 to 93.26%. The maximum yields for the stands within the study area were 329.98 m3/ha, 330.71 m3/ha, 171.35 m3/ha, and 127.46 m3/ha, respectively. The communities defined by a dominant species to which a growth curve was attributed will serve as the basis for estimating the carbon balance in this region of the state of Jalisco, Mexico.

Criteria to set conservation priorities for natural areas in the Sinaloa region, Mexico

2023-08-18T19:25:04+00:00

To identify Conservation Priority Sites (CPS), several models are currently available, using geographic information systems, mathematical algorithms or more traditional field methods among which the Determination Index (DET) method using a set of criteria, Specific Diversity Index, Ratio of Species of Concern, Relative Scarcity Index and Habitat Fragility Index to assess conservation stakes over wild plant species and habitats patterns. The aim of this study is to establish CPS in the southern Sinaloa region, Mexico using the DET method. In 2017 eight sampling sites were assessed, two in mangroves, three in dry forest and three in semi-deciduous forest, each 0.12 ha in surface area. Species-area curves were analysed to quantify species diversity. The ratio of species of concern was calculated using a Floristic Originality Index. A relative scarcity index was calculated from each type of vegetation surface area. Fragility of habitats was estimated over five levels of resilience. The resulting DET evidences semi-deciduous forest sites as the highest conservation priorities, due to higher species diversity values, number of species of concern and scarce surface. DET method enabled the ranking of CPS in the study area, moreover, it is recommended as a useful tool for natural and anthropized landscape planning and over conservation patterns.

Relationship of environmental factors with the productivity of Eucalyptus globulus in the northern Peruvian Andes

2023-08-18T19:04:21+00:00

The South American Andes are a group of mountains that extend across the continent from north to south, generating a diversity of climates. The species of the genus Eucalyptus have a high growth rate and adaptability. Eucalyptus globulus has been installed on many slopes of the northern Peruvian Andes above 3,000 meters of altitude (Cajamarca - Peru), but its growth and productive viability are unknown. The objectives of this study were i) to determine the season quality of Eucalyptus globulus above 3,000 meters, ii) to evaluate the relationship between physiographic and edaphic variables on growth and productive viability, and iii) to evaluate the potential effect of altitude on growth. Station quality was determined by estimation of the Site Index, using three base growth models (Bertalanffy-Richards, Hossfeld and Korf) and two derivation methods (Algebraic Differences - ADA and Generalized Algebraic Differences - GADA). The relationship between environmental factors and Site Index was determined using the Spearman correlation coefficient. The potential effect of altitude was evaluated by comparing station quality curves. It was determined that the dynamic equation derived from the Bertalanffy-Richards model and GADA best explained the variability of H (96.7%). The SI was well correlated with distance to water bodies and to a lesser degree with solar radiation, effective depth and base saturation. In addition, slow growth was evidenced in the initial stage of the plantation due to the effect of altitude, generating low yields.

Simple fence modification to facilitate huemul Hippocamelus bisulcus movement across forestry lands

2023-08-04T15:45:34+00:00

Fencing to contain livestock movement, demarcate properties and protect economic assets has been one of the main factors restricting wildlife movement. However, research assessing the impact of fences on large mammals in southern South America is scarce. We modified livestock fences by clipping the bottom wire to enable endangered huemul deer (Hippocamelus bisulcus) to cross in and out of forest plantations. Huemul showed a preference for crossing through areas where bottom wire strands had been removed. There was also a greater crossing frequency for fences located at lower elevation. Implementation of this simple management technique increased the availability of crossing areas, thereby facilitating huemul movement. Further fence modifications must seek to improve conditions of intervening habitat where huemul live and move, and thus prevent further population decline of this threatened species.

Ravine forests of the of the Maule coast: spatial and vegetational evaluation in a context of climate change and anthropic impacts

2023-09-03T00:39:36+00:00

In the coastal mountain range of the Maule region, 23 ravine rain forests dominated by canelo (Drimys winteri) and various native myrtaceae species were described in phytosociological terms in a study published in 1988. Thirty years later, 20 of those forests were located again in order to document their current situation in a context of successive anthropic impacts and climate change. Changes in land cover were evaluated through the comparative analysis of Landsat images from 1987, 2003 and 2017; the changes in plant composition, characterizing the vascular flora by means of the modified Braun-Blanquet phytosociological method and; the natural regeneration of woody species in plots of 1 m² inside and outside the ravine forests. Between 1987 and 2017, the area occupied by native forest in the circular areas included in the study was reduced by 72 %. The importance and presence of significant species reported in the original inventories decreased in the hygrophilous forests and sclerophyllous and invasive species entered. The regeneration of native trees and native creeping and climbing species was higher inside the ravine forests, while the germination of native shrubs was higher at the edge of these. The modification of the surrounding matrix of forests due to the increase in anthropic pressure and an advance in stressful conditions as a consequence of climate change explain the observed changes.

In vitro cloning of a selected Eucalyptus pilularis tree and genetic stability analysis of micropropagated plants

2023-09-22T15:38:23+00:00

Establishing vegetative propagation techniques to promote the rejuvenation/reinvigoration of genotypes is essential for the rescue of adult trees of the Eucalyptus genus used in species and provenance tests. The aim of this study was to evaluate the induction of epicormic buds and shoots in pruned branches and the in vitro establishment, multiplication, genetic fidelity and elongation of three 44-year-old Eucalyptus pilularis selected plants. M1, M2 and M3 represent selected plants 1, 2 and 3, respectively. M1 was the best in terms of number of epicormic buds, number of shoots, oxidation, and non-responsive explants. In the establishment phase, M3 was the best in contamination, number of shoots, and shoot length. In the multiplication phase, the highest vigour and shoot length values of were found in the 15th subculture. Phenolic oxidation had its highest value in the 12th subculture, decreasing from the 13th. The highest value for number of shoots was found in the 11th subculture. No polymorphism was observed between the selected plants and the clonal plants obtained in the 15^th subculture. In elongation, the use of culture medium containing 0.10 mg L^-1 BAP and 1.00 mg L^-1 NAA provided the lowest means for oxidation, and the highest for vigor, number and length of shoots per explant. The emission of adventitious roots was observed, demonstrating that, through micropropagation, it was possible to induce the competence to root the material, even at an advanced ontogenetic age.

Survival and phenology of Pinus patula ramets from asexual seed orchard

2023-08-04T15:39:26+00:00

In asexual seed orchards, genetically improved seed is obtained to produce plants destined for forest plantation programs, which will help increase wood quality, productivity and reduce cutting cycles. The objective of this work was to evaluate the survival, height increase and vegetative and sexual phenology of juvenile ramets from an asexual seed orchard of Pinus patula due to the effect of the geographical origin of the ortets. In addition, it was sought to determine the existence of correlation between the characteristics evaluated with the bioclimatic variables of the origin of the ortets. Survival was evaluated with analysis of variance and Tukey's tests of means. Correlation coefficients were obtained with the Pearson test. Statistical differences were found due to the geographical origin of the ortets and the cloned tree. The highest survival was found in ramets with scions from ortets of Tlahuiltepa, Hidalgo and Ahuazotepec, Puebla, both with 94%. The best clones were: 19 and 20 (Ahuazotepec) and 75 (Agua Blanca, Hidalgo) with 100% survival. Correlation was found between female sexual phenology and nine bioclimatic variables. It is concluded that there is greater female flowering in ramets made with scions from ortets of elevation, temperature and rainfall lower than those of the site where the asexual seed orchard of Pinus patula evaluated in the present investigation was established.

Initial growth and functional Austrocedrus chilensis and Nothofagus dombeyi under different light and humidity conditions

2023-08-04T16:20:09+00:00

Andean cypress and coihue are endemic species of the Andean-Patagonian forest of Argentina, which grow in pure or mixed formations. Both have an important ecological role in the region and great productive potential. However, knowledge about how humidity and light condition its early development is limited. In this study, under nursery conditions during two growing seasons, was determined the response of cypress and coihue to the combined effect of different light and soil moisture regimes on survival; height, collar diameter, and stem volume increment; and in the following functional traits: leaf thickness and tensile strength, specific leaf area, total leaf area, leaf area/sapwood area to collar ratio, dry weight of the different compartments (leaves, branches, and roots), and internode length. Both species showed similar responses to the factors studied in survival and initial development, although coihue showed, in general terms, greater growth and lower survival than cypress. A low light level negatively affected the development of both species. The humidity levels used (>8 %) did not have significant effects on growth, but they did show effects on the functional traits of both species and conditioned the survival of coihue. It is concluded that the best performance of both species occurs in intermediate light conditions.

Evaluation of germination and dormancy of seeds of three Andean native forest species in Azuay-Ecuador

2023-10-26T15:40:18+00:00

Physiological processes such as seed germination and dormancy under controlled conditions of Andean Forest species are poorly known. For this reason, the objective of the present study was to evaluate in three forest Andean species: Myrcianthes rhopaloides, Oreocallis grandiflora, and Weinmannia fagaroides, the pre-germination, chemical and physical treatments in relation to germination and dormancy. Firstly, the seeds were disinfected and placed in Petri dishes, to evaluate germination with: a) cold stratification, b) hot humid stratification, c) immersion in GA₃ at 270 ppm and d) acid scarification (immersion in 10 % H₂SO₄). In a growth chamber under controlled environmental conditions, germination was monitored for a period of 30 days. The seeds’ physical dormancy was evaluated by an imbibition test. Morphological dormancy was evaluated using 100 seeds and 20 embryos per species that were extracted and measured with an electron stereoscope. The results show that the seeds of the species under study increased the percentage and speed of germination when gibberellic acid was applied compared to the other treatments, while the effect of acid scarification was significantly lower in all species. Likewise, it was found that the seeds lack physical and morphological dormancy, however, when analyzing the behavior of the seeds in acid, the presence of a physiological type of dormancy is suggested. These results support the knowledge of these Andean Forest species for the purposes of conservation and plant production for reforestation.

Variation in growth of Pinus patula in an asexual seed orchard in Huayacocotla, Veracruz Mexico.

2023-01-09T18:26:45+00:00

Pinus patula seeds are in high demand for the establishment of plantations in Mexico and around the world because of the fast growth of this species. However, genetically improved germplasm of forest species is scarce in Mexico. For this reason, in 2012, the Mexican government started a program of asexual seed orchards with species of the Pinus genus to meet the germplasm demand. Thus, the objectives of the present research were: to evaluate the height, diameter at breast height, and volume of Pinus patula clones in an asexual seed orchard and to estimate the heritability of these traits. The asexual seed orchard was established in 2012. The diameter at breast height and total height (DBH) were measured and the volume of each ramet was calculated. Subsequently, clonal heritability was estimated for each trait in the four-year-age clones. Differences were found among clones. The average height was 4.38 m, and it varied from 3.39 to 4.80 m for the clones 103 and 28, respectively. The average DBH was 5.46 cm and varied from 3.98 to 6.52 cm for clones 103 and 25, respectively. The average volume was 6.23 dm³ showing a range from 2.62 to 9.53 dm³ for clones 103 and 25, respectively. Clones of Pinus patula had high values of height, DBH, and volume. Heritability values for height, DBH and volume were 0.655, 0.508 and 0.575, respectively. Thus, these traits show high heritability, in other words, they are influenced by genetic component.

Ecosystem services the dry forest of the Cazaderos parish, Zapotillo canton, Loja province, Ecuador

2023-08-16T18:14:21+00:00

In the Cazaderos parish located in the southwest of Ecuador, the goods and services offered by the dry forest were recognized, quantified and ranked. The proposed methodology started of the elaboration of a socioenvironmental diagnosis and the classification was made based on the Millennium Ecosystem Assessment (MEA). According to the MEA classification three ecosystem services were determined of provision, regulation and cultural that the dry forest offers to the people of the Parish. In the provision services they were identified: the availability of fresh water mainly for human consumption, timber forest products with endemic and representative species, and non-timber forest products (medicines, oils, fibers, dyes and crafts). As regulation services regulation storage of water in water recharge areas, and the protection of riparian zones were identified; as culturals highlights cultural heritage, ecotourism, ense of belonging and scenic beauty. Although these services provide multiple environmental benefits to the Parish there are negative factors such as of change in land use that alter its functionality. In this sense, given the importance that ecosystem services of the dry forest actions aimed at their protection and conservation are proposed.

Effects of the plantation forests on nutrient export, soil erosion, sediment transport and macro benthic invertebrates in the South-central Chile:

2023-07-31T14:07:16+00:00

This is a review of studies related with the effects generated by the fast-growing exotic plantations (PECR) of Pinus radiata and Eucalyptus spp. on water quality of watersheds in south-central Chile, at different spatial and temporal scales. The analyzed data comes from a region between 36° - 40° S in the Central Valley and includes both mountain ranges, the Coastal and the Andes. Studies on the watershed’s capacity to export nutrients indicate that the conversion from native forests to forest plantations implies a net loss in nitrogen (N) and phosphorus (P) retention capacity. Consequently, watersheds with plantations coverage experience a net loss of these nutrients. Similarly, in watersheds dominated by Eucalyptus globulus, nitrogen retention decreases, especially NO3-N, and is partially reversed as a wider riparian vegetation is maintained. Studies of soil erosion and sediment transport losses show that clearcut harvesting has significant impacts on water quality, increasing sediment transport rates in streams. However, when soil conservation measures are practiced, erosion rates decrease significantly during forest harvesting. Some of the physical-chemical characteristics of the water, such as pH and temperature, are similar between streams with native forests and forest plantations. There is also a tendency for a decrease of richness and abundance of the macrobenthic invertebrates community due to the replacement of riparian vegetation by Eucalyptus spp.

A systematic review of remote sensing data to assess dry forests attributes.

2023-09-07T12:44:38+00:00

Ecological indicators are widely used to assess vegetation attributes and can be quantified through field-based and/or remote sensing data. Particularly, advances in remote sensing have allowed monitoring of dry forest attributes across multiple spatiotemporal scales. The objectives were to analyze the recent state-of-the-art in using remote sensing data as ecological indicators to assess dry forest attributes; identify the data source of remote sensing indicators used; and identify the geographical distribution of these studies. A systematic search was conducted for original research articles that used remote sensing data as ecological indicators of dry forests attributes. Composition indicators were assessed with the same frequency at species/population and landscape/region hierarchy levels. However, structural indicators were mainly assessed at the species/population level, and function indicators at the community/ ecosystem level. Over 60 % of the articles considered one ecological indicator, 20.45 % two, and 18.18 % used three indicators. Over 47 % considered field surveys and remote sensing data to assess dry forest attributes, and more than 52 % only had remote sensing data. Four out of the 88 articles analyzed report a weak relationship between field surveys and remote sensing data. Landsat and MODIS products were the most frequently used, with South America being the most studied continent. Observations and products from a single sensor, as well as using only one ecological indicator or one hierarchy level, would not be enough to represent the complexity of dry forest ecosystems.