Radial growth in Pinus patula Schltdl. & Cham. and its relationship with growing space and climatic factors Scientific article
Crecimiento radial en Pinus patula Schltdl. & Cham. y su relación con el espacio de crecimiento y los factores climáticos
Available online: 2020-01-24
/ pages 157–172
Introduction: Annual variation in growth ring characteristics has an impact on productivity
and wood quality.
Objective: To evaluate radial growth in two Pinus patula Schltdl. & Cham. plantations of different
ages and thinning intensity, as well as its relationship to interannual variation in temperature
Materials and methods: Growth ring characteristics were analyzed in wood samples from 13-
and 23-year-old plantations, subjected to three thinning intensities (null, light and moderate).
The characteristics were related to climate data during the years of ring formation using
Pearson’s correlation analysis.
Results and discussion: In the 1995 plantation, ring characteristics did not show significant
differences (P > 0.10) between plots with and without thinning, due to excessive competition
and crown recession. Ring width, and early and latewood width, was significantly associated
(P < 0.10; r ≥ 0.40) with average minimum temperature. In the 2005 plantation, trees from
the thinned plots showed greater ring width, earlywood width and basal area increment than
those from the unthinned plot. In this plantation only latewood width was positively associated
(P < 0.10; r = 0.69) with temperature and negatively (P < 0.10; r = -0.61) with annual rainfall.
Conclusion: Growing space and competition intensity mainly affected ring and earlywood
width. Environmental factors influence ring characteristics.
Growth and secondary metabolites of Stevia pilosa Lag. in three edaphoclimatic conditions in the state of Hidalgo, Mexico
Crecimiento y metabolitos secundarios de Stevia pilosa Lag. en tres condiciones edafoclimáticas en el estado de Hidalgo, México
Available online: 2020-01-24
/ pages 173–187
Introduction: The distribution of Stevia pilosa Lag. and its metabolite content with therapeutic properties have been documented; however, there are no reports of in situ development and factors influencing plant growth.
Objective: To quantify the growth and phytochemical and nutrient content of S. pilosa plants in situ under three edaphoclimatic conditions in the state of Hidalgo, Mexico.
Materials and methods: At the three sites called Huasca de Ocampo (HO), Mineral del Chico (MCh) and Mineral del Monte (MM), with different climates, soil types and elevation ranges, soil was collected and three plant samplings were carried out to follow the development of the species.
Results and discussion: The number of plants varied according to the sampling sites, being higher in MCh (12 plants·m-2). Growth rate and leaf area were directly related. In MCh and MM plants, net photosynthesis only supplied the demand in the first two samplings, where there was significant accumulation (P ≤ 0.05) of matter, while in HO it supplied all the samplings. MCh and HO plants had a higher nutrient concentration (P ≤ 0.05). MCh and MM plants showed a higher concentration of phenols and flavonoids, and HO plants stood out in total terpenes.
Conclusions: The edaphoclimatic conditions at the three sites in the state of Hidalgo modified the presence, form of growth and development of S. pilosa.
Regional analysis of the change factors in the oak (Quercus sp.) forest cover in the Tehuacán-Cuicatlán region, Mexico Scientific article
Análisis regional de los factores del cambio de cobertura del bosque de encino (Quercus sp.) en la región Tehuacán-Cuicatlán, México
Available online: 2020-01-31
/ pages 189–205
Introduction: Oak (Quercus sp.) forests are scarcely represented in Mexico’s Protected Natural Areas, and are highly susceptible to deforestation.
Objective: To assess the regional dynamics of deforestation and recovery, as well as the factors of change in land cover and use (CLCU) in the oak forest of the Tehuacán-Cuicatlán Region (TCR) which includes the Tehuacán-Cuicatlán Biosphere Reserve (TCBR) polygon and its zone of influence.
Materials and methods: The dynamics of the CLCU was analyzed in two periods; these were before (1979-2001) and after (2001-2011) the TCBR decree issuing. The analysis of the factors consisted of two stages: logistic regression analysis from the spatial interpolation of the factors, and analysis of the municipal socioeconomic trends based on change rates.
Results and discussion: The oak forest was deforested prior to the TCBR decree, with a -0.97 % annual change rate. Deforestation was associated with low-slope areas, close to localities with a larger male population. In contrast, in the post-decree period its recovery stood out (0.22 %), which was associated with high-slope and high-elevation areas and a decrease in the male population.
Conclusion: The TCBR decree must not be thought as the main cause of change in the CLCU processes; however, an indirect influence from it should be accepted.
Analysis of the physical work environment in sawmills in El Salto, Durango, Mexico Scientific article
Análisis del ambiente físico del trabajo en aserraderos de El Salto, Durango, México
Available online: 2020-01-31
/ pages 207–219
Introduction: Sawmill workers carry out their work in an adverse physical environment that influences their well-being, not knowing if safety levels in the area are acceptable.
Objective: To analyze workers’ exposure to noise, thermal comfort, and lighting at five workstations in six sawmills in the El Salto region of Durango, Mexico.
Materials and methods: The physical variables of the work environment were measured directly at three times of the day for seven workdays at five workstations (forklift, edger, swing saw, resaw, and head saw). The maximum allowable time of exposure to noise, thermal comfort through effective temperature, and lighting of the work area were determined. Statistical differences in physical variables between workstations, sawmills and times of the day were detected by analysis of variance and Kruskal-Wallis median range comparison tests.
Results and discussion: The noise level (85 to 102 dB[A]) represents a greater hearing risk at the head saw, resaw and swing saw workstations as it exceeds 90 dB (A). Thermal comfort was 20 °C, which ensures that the worker can be exposed 100 % of the time of the workday to this temperature. Lighting levels were high, exceeding 2 000 lx.
Conclusions: The noise and lighting levels are high in the assessed sawmills and pose a risk to the safety of workers if the mandatory use of ear and eye protectors is not monitored.
Height-diameter-age equation systems for Pinus arizonica Engelmann and Pinus durangensis Martinez in mixed-species stands in Durango, Mexico Scientific article
Sistemas de ecuaciones de altura-diámetro-edad para Pinus arizonica Engelmann y Pinus durangensis Martínez en rodales mezclados de Durango, México
Available online: 2020-02-10
/ pages 221–239
Introduction: Total height (H) and diameter at breast height (DBH) are important variables in forest inventory and they are the basis for growth and yield systems.
Objective: To generate three prediction and projection equation systems for Pinus arizonica Engelmann (Pa) and Pinus durangensis Martinez (Pd) in mixed stands in Durango, Mexico.
Materials and methods: The outside-bark DBH equations as functions of the inside-bark DBH were developed and the H-DBH relationship was extended to three relationships with the use of age (A): H-DBH, H-A and DBH-A. The equation systems of H-DBH-A were developed from a database of 46 and 66 stem analysis trees with 601 and 760 longitudinal measurements of Pa and Pd, respectively. The equations were fitted with apparently unrelated regression and Dummy variables approach with common and specific parameters.
Results and discussion: The relationships showed significant accuracy in the assessed fitting statistics (adjusted coefficient of determination, root mean square error, Akaike's information criterion, standard error of the estimate and bias). The inverse equations of the three relationships formed a global system of prediction and projection equations.
Conclusions: The equations are useful for predicting and projecting H and DBH and they can be used as input variables in growth and yield models.
Modeling of landslide sensitive areas using GIS in semi-arid forests and evaluation in terms of forest rehabilitation
Modelación de áreas susceptibles a deslizamientos de tierra utilizando SIG en bosques semiáridos y evaluación en términos de rehabilitación del bosque
Available online: 2020-04-20
/ pages 241–255
Introduction: In order to increase, protect, and sustain forest assets, it is important to determine the factors that affect forestry activities and minimize their impact. In this study, the landslide factor in forestry applications was tackled. The negative effect of unpredictable factors of forestry
activities (road construction, harvesting, afforestation, etc.) can be reduced by calculating and modeling the landslide susceptibility ratios of degraded forests.
Objective: To demonstrate the applicability of a landslide susceptibility map for supporting decision makers in the assessment of semi-arid and landslide-sensitive forestlands in forestry activities and rehabilitation works.
Materials and method: Six models were introduced by using the fuzzy inference system (FIS) and modified analytical hierarchy process (M-AHP) approaches. A combination of elevation, slope (degree), distance to faults, lithology, aspect, and plan curvature was used in the models.
Results and discussion: The most successful models under the FIS and M-AHP approaches were FIS Model 3, and M-AHP Model 1, with areas under the curve (AUC) of 80.2 %, and 78.1 %, respectively. Using precision forestry by making decisions based on the area’s landslide susceptibility in the management and planning stage (e.g., construction of forest infrastructure facilities, afforestation, and forest harvesting and rehabilitation), will increase the success of forestry activities.
Conclusion: It is very important to determine the landslide areas in advance and reliably for effective execution of forestry practices in landslide sensitive forestlands, in order to increase the success of forestry activities in accordance with the sustainable forest management approach.
Choice experiments for the management of Los Mármoles National Park, Mexico Scientific article
Experimentos de elección para el manejo del Parque Nacional Los Mármoles, México
Available online: 2020-04-20
/ pages 257–272
Introduction: the planning and management of activities in Los Mármoles National Park should include the opinions of users and visitors in order to generate sustainable economic alternatives in line with conservation objectives.
Objective: to estimate the economic value of the implementation of an improvement plan (access roads, forest health, biodiversity protection and recreation spaces) for the management of Los Mármoles National Park.
Materials and methods: the economic value of implementing an improvement plan was estimated through choice experiments, by means of a conditional logit Model. To this end, key actors were interviewed, participatory diagnostic workshops were held and a survey was applied to 144 tourists, who expressed the order of preferences for the attributes of the improvement plan.
Results and discussion: the survey participants assigned greater willingness to pay for the forest health attribute (16.51 MXN) than to access roads and parking sites (13.74 MXN) and biodiversity protection
(9.28 MXN). The attribute on improvements to recreational spaces was not statistically significant, reflecting a greater appreciation for maintaining the site’s undisturbed conditions.
Conclusions: the choice experiments in the management of policies for the handling of Natural Protected Areas allowed to identify the areas of opportunity and value them economically, through the opinion of the actors involved in the activities of Los Mármoles National Park.
Changes in temperature and rainfall caused by three crops in the state of Veracruz, Mexico Scientific article
Cambios en la temperatura y precipitación causados por tres cultivos en el estado de Veracruz, México
Available online: 2020-04-15
/ pages 273–289
Introduction: The establishment of new crops may cause climatic alterations at the local or regional level.
Objective: To analyze temperature and rainfall variation by simulated replacement of current vegetation through the introduction of sugarcane (Saccharum officinarum L.), jatropha (Jatropha curcas L.) and moringa (Moringa oleifera Lam.) in the central region of the state of Veracruz, Mexico.
Materials and methods: Simulations of environmental temperature and rainfall for each crop and the control (current conditions: mixed crop, perennial trees, mixed forest and irrigated agriculture) were made with the Regional Climate Model (RegCM4). The model was evaluated by comparative analysis between simulations and observed data, using the mean square error and the root-mean-square error as measures of dispersion.
Results and discussion: Regions with soils devoid of natural vegetation, such as agricultural soils, would have greater climatic variability. In these soils, the displacement of current vegetation by sugarcane would generate the greatest thermal alterations with a decrease of 0.7 °C, while with jatropha and moringa, the decrease would be 0.3 °C. Regarding rainfall, the RegCM4 bias increases when there are high variations in elevation, thus other models should be explored.
Conclusions: The introduction of moringa or jatropha for bioenergy purposes would be a low climatic impact alternative, while sugarcane is not considered suitable for these purposes due to the greater climatic impact that it would have in the region.
Forest volume estimation techniques with special emphasis on the tropics
Técnicas de estimación del volumen forestal con especial énfasis en los trópicos
Available online: 2020-04-20
/ pages 291–306
Introduction: Volume is an important variable in forest management since it allows
evaluating the growth and development of individuals in stands.
Objective: To analyze the techniques for estimating forest volume with an emphasis on
Materials and methods: The work was developed with the non-probabilistic snowball
technique, in which the bibliography reported in an investigation suggested the search for
similar works to enrich the subject.
Results and discussion: In tropical forests, tree measurement variables provide valuable
information for estimating stem or total volume using a xylometer, Pressler and standing tree
volume formulas, dendrometric bodies, rigorous volume estimation, graphical method or
conventional equations and neural networks. Accurate volume information is only obtained
with the xylometer technique, which is the only one that allows estimating volume using the
direct method. The rigorous volume estimation technique is the most used in the tropics to
obtain the volume of individual sections, which are fitted by conventional or neural network
equations to estimate the total volume. Most researchers selected the best models using the
coefficient of determination, root mean square error, bias, Durbin-Watson test, and Akaike
and Bayesian information criteria.
Conclusion: Model selection depends directly on the researchers; however, the xylometer
technique is the only one that estimates volume with the direct method and in an accurate way.
Outplanting performance of Pinus patula Schltdl. & Cham. as an effect of root pruning and containers used in the nursery Scientific article
Crecimiento en campo de Pinus patula Schltdl. & Cham. como efecto de la poda radicular y los contenedores utilizados en vivero
Available online: 2020-04-15
/ pages 307–319
Introduction: The production of seedlings in containers implies the risk of deforming the root. This damage persists and increases after outplanting causing negative effects on the plants.
Objective: To evaluate outplanting performance of Pinus patula Schltdl. & Cham. as an effect of root pruning and containers used in the nursery.
Materials and methods: Nine-month-old seedlings were grown in three 170 cc containers: plastic tray, polystyrene tray and grid with containers with 54, 77 and 42 cavities, respectively. The cavities were impregnated with copper hydroxide to encourage chemical root pruning; additionally, an aerial root pruning treatment was included (containers with lateral openings). Survival and growth of P. patula were evaluated under field conditions during two years in 72 plants per treatment, randomly distributed in six blocks or replications.
Results and discussion: Pruned and unpruned plants showed significant differences (P ≤ 0.05) in survival (89 vs. 79 %), height (154.0 vs. 147.1 cm) and relative annual growth rates of diameter (0.97 vs. 0.93 cm·cm-1·year-1) and height (0.97 vs. 0.92 cm·cm-1·year-1). Plants in plastic containers and polystyrene trays had the best growth and survival rates. The interaction container*pruning was not significant. In spite of starting with the lowest sizes, the plants in containers designed for aerial root pruning had similar characteristics to those grown in the same containers with and without chemical root pruning.
Conclusion: Root pruning favored survival and growth of P. patula after outplanting and had a greater effect than the type of container used.