Study of the production in a custom-cut sawmill through the use of discrete event simulation and experimental design
Estudio de la producción en un aserradero de corte cualitativo a través del uso de simulación de eventos discretos y diseño de experimentos
Available online: 2019-05-03
/ pages 291-304
Introduction: When sawing logs without diameter sorting, the cutting program generates decisions and routes depending on the log’s appearance and machine load.
Objective: To optimize the production flow of a custom-cut Pinus radiata D. Don sawmill, through detection and analysis of critical machines, using discrete event simulation and experimental design.
Materials and methods: Two simulation models were developed for sawing logs with lengths of 2.5 and 5.0 m, and diameters between 34 and 44 cm to produce sawnwood with a thickness of 5/4" with variable width. The number of logs processed per shift was the response variable of the model. Heavily-used machines and transports with long queues were candidates for critical machines. The impact on production was determined by means of experimental design, where the factors assessed were: (A) delivery from bandsaw carriage 1 to band saw 3, (B) increased debarker capacity, (C) failures eliminated from bandsaw 1 and 2, and (D) direct delivery from bandsaw 2 to edger 2.
Results and discussion: Modifications to the production flow were proposed because factors B, C and D significantly increased (P = 0.1) the production level (logs per shift); the increases over the sawmill’s initial condition were 13 and 18 % for lengths of 2.5 and 5.0 m, respectively.
Conclusion: Simulation and experimental design can be applied in small and medium-sized sawmills to improve production when processing logs without diameter sorting.
Influence of temperature and irradiation on starch concentration in Carya illinoinensis K. Koch varieties Wichita and Western
Influencia de la temperatura e irradiación en la concentración de almidón en Carya illinoinensis K. Koch variedades Wichita y Western
Available online: 2019-05-16
/ pages 305-314.
Introduction: The pecan tree (Carya illinoinensis K. Koch) is a species native to northern Mexico and the Southeastern United States; the two countries dominate pecan production worldwide.
Objective: To determine the influence of temperature and irradiation on the starch concentrations in the root and trunk of C. illinoinensis varieties Wichita and Western.
Materials and methods: Starch was quantified monthly during the July 2016 - June 2017
production cycle. Average monthly temperature and irradiation data were obtained from the
INIFAP weather station at the La Laguna Experimental Field. Regression analyses were done
using SPSS 18.0.
Results and discussion: The Wichita and Western varieties showed a significant relationship (P < 0.05) between root starch cincentrations and environmental factors; in the trunk, the relationship was not significant. In both varieties, the maximum starch concentrations in the root is recorded when the temperature ranges from 15 to 20 °C, and the irradiation rate ranges from 10 to 15 MJ·m-2.
Conclusion: The Wichita variety is the best adapted to high temperatures and irradiation
rates in the Comarca Lagunera region.
Tree diversity and stored carbon in cocoa (Theobroma cacao L.) agroforestry systems in Soconusco, Chiapas, Mexico
Diversidad arbórea y carbono almacenado en sistemas agroforestales de cacao (Theobroma cacao L.) en el Soconusco Chiapas, México
Available online: 2019-06-01
/ pages 315-332
Introduction: Cocoa (Theobroma cacao L.) yields in Chiapas, Mexico remain low, but can be improved with agroforestry designs that consider tree composition to ensure diversity and carbon sequestration.
Objective: To determine tree diversity and stored carbon at three elevational levels of cocoa agroforestry systems in Soconusco, Chiapas.
Materials and methods: Representative 50 x 20 m plots were established at three elevational levels (0 to 50 m, 51 to 100 m and ≥101 m). Species were counted and classified taxonomically. Diameter at breast height, height of each species, diversity, similarity between pairs of heights, and carbon storage were estimated.
Results and discussion: Richness was 35 tree species selected by the producers to shade the cocoa crop. These were grouped into 32 genera and 22 families. Abundance was 199 trees, with abundance per plot and diversity being the highest at ≥101 m. Lower diversity was associated with heights with less equity between abundance and richness. Carbon stored in aerial biomass ranged from 224.9 to 362.1 Mg·ha-1; the amount was highest at lower elevations (0 to 50 m).
Conclusions: Agroforestry systems had medium to high diversity. Species distribution, by elevational level, responds to the interests of the producers and to the composition of the natural forest. The amount of stored carbon was high, due to the abundance, richness and dominance of the species.
Community participation for carbon measurement in forests of the Monarch Butterfly Biosphere Reserve, Mexico
Participación comunitaria para la medición de carbono en bosques de la Reserva de la Biosfera Mariposa Monarca, México
Available online: 2019-06-12
/ pages 333-352
Introduction: Community participation is an effective strategy for forest management and ecosystem services management.
Objectives: To apply participatory methods for estimating carbon stocks in community owned forests and to identify land uses and conflicts that may influence the maintenance of these forests.
Materials and methods: Participatory mapping workshops were held in four communities. Members were instructed in the measurement of tree-size parameters to estimate aboveground carbon in forest biomass. Work was conducted in the Monarch Butterfly Biosphere Reserve, a priority area for REDD+ in Mexico.
Results and discussion: Awareness-raising, acceptance and flexibility processes were identified towards the incorporation of participatory tools, both for future participation in carbon markets and to improve existing forest management practices of the communities. Carbon values obtained through participatory methods were consistent with those identified by experts for the forest types included in this study. Averages of 112, 98 and 91 Mg C·ha-1 were estimated in conifer-dominated, broadleaf-dominated and mixed-species forest sites, respectively. In some communities there are conflicts over land ownership boundaries and there are some internal conflicts where community agreements have not been respected.
Conclusion: Participatory methods of tree carbon mapping and measurement support forest management through the generation of reliable data that can facilitate community management of resources. Carbon stocks were associated more with the degree of forest conservation, than with vegetation type, and forest disturbance is more associated with internal and external conflicts than with forest management practices.
Trichoderma harzianum Rifai as a biocontrol of Fusarium circinatum Nirenberg & O´Donnell in seedlings of Pinus greggii Engelm. ex Parl. in three substrates
Biocontrol de Trichoderma harzianum Rifai sobre Fusarium circinatum Nirenberg & O´Donnell en plántulas de Pinus greggii Engelm. ex Parl. en tres sustratos
Available online: 2019-06-13
/ pages 353-367
Introduction: Damping-off is a common disease in forest nurseries that causes significant economic losses worldwide.
Objective: To evaluate the pathogenicity and incidence of Fusarium circinatum Nirenberg & O´Donnell in seedlings of Pinus greggii Engelm. ex Parl., and the use of Trichoderma harzianum Rifai as a biocontrol in three substrates.
Materials and methods: The phytopathogenic fungus F. circinatum (strain SF5) and the antagonist T. harzianum (commercial strain T-22 KRL-AG2) were inoculated into P. greggii. Three substrates based on peat moss, pine sawdust and pine bark were used. The incidence of the disease and the morphological indices of the plant (stem diameter, height, aerial dry weight/root dry weight ratio, slenderness index and Dickson quality index) were evaluated. The data were subjected to an analysis of variance (GLM procedure of SAS version 9.0) and Tukey's multiple comparison test (P ≤ 0.05).
Results and discussion: Pathogenicity was tested using Koch's postulates. The incidence of the disease was high (> 93 %) in substrates based on peat moss and pine bark, and was lower in the sawdust-based substrate (78 %). Trichoderma harzianum and the sawdust-based substrate reduced the incidence to 66 %. Plant quality, based on the morphological indices, was highest in the peat moss substrate.
Conclusion: Fusarium circinatum is pathogenic in P. greggii; the sawdust-based substrate and T. harzianum reduced the incidence of the disease in the seedlings.
Peasant knowledge about the soils of the Zicuirán-Infiernillo Biosphere Reserve
Conocimiento campesino sobre los suelos de la Reserva de la Biosfera Zicuirán-Infiernillo
Available online: 2019-06-13
/ pages 369-381
Introduction: Peasants in La Huacana, Michoacán, have developed local knowledge about natural resources, including soil.
Objective: To compare local soil knowledge with technical knowledge to elucidate whether peasants identify horizons and give them names and attributes.
Materials and methods: Thirty-one trial pits were made and the profiles were described in collaboration with the peasants. Samples were taken by horizons and strata to determine their properties in the laboratory. The obtained data were subjected to discriminant analysis and principal component analysis.
Results and discussion: The soil classes present in the study area were: Polvilla, Barrosa, Charanda, Tocura, Cementante, Cascajo, Balastre and Tepetate. The peasants named the soil profile horizons/materials as soil classes, making it possible to find several soil classes in one profile. These classes were statistically differentiated in the profile on the basis of physical and chemical properties; 72.13 % of the cases were correctly classified.
Conclusion: For the first time, it is reported that the names of soil classes corresponded to horizons and layers of recently buried soils and not to the complete soil profile.
Benefits from visualization of environmental factor gradients: a case study in a protected area in central Russia
Beneficios de la visualización de gradientes de factores ambientales: un caso de estudio en un área protegida en Rusia central
Available online: 2019-07-31
/ pages 383-397
Introduction: Ecological scales include plant species, which are responsive to changes in habitat conditions. Such plants act as phytoindicators that integrate many environmental factors.
Objective: To identify suitable habitats for searched-for plant species based on phytoindication data.
Materials and methods: Altogether, 47 square plots (100 m2) were established within a selected forest area of the Mordovia State Nature Reserve. In each plot, species composition was recorded for further analysis, and the mean values of four environmental factors (shading, soil moisture, soil nitrogen, and soil pH) were calculated using the Tsyganov ecological scale. To visualize changes in factor values, contour maps were created for each factor. To reveal differences between species composition in study plots, Jaccard’s similarity index was calculated.
Results and discussion: All study plots have been arranged mainly along gradients of three soil parameters, namely pH, nitrogen availability and moisture, while habitat shading has not acted as strongly. Gradient maps obtained of four selected environmental factors demonstrated remarkable similarity. This suggestion is confirmed by the distinguishing of three areas because of overlapping of these maps. Similarity between values of environmental factors and plant distribution was determined. The use of phytoindication methods allows showing changes in the values of environmental factors in a forest area, and being combined with a species similarity index, it is possible to predict habitat suitability for threatened plants.
Conclusions: The possibility of indicating and finding an area suitable for inhabitation of
plants based on the phytoindication ecological scale approach was determined. As threatened plants have a narrower range of environmental conditions, this method is especially suitable for these investigations.
Eichhornia crassipes (Mart.) Solms: an integrated phytoremediation and bioenergy system
Eichhornia crassipes (Mart.) Solms: un sistema integral de fitorremediación y bioenergía
Available online: 2019-08-09
/ pages 399-411
Introduction: Eichhornia crassipes (Mart.) Solms is an aquatic plant that reproduces rapidly in polluted water. Due to the high adsorption capacity of heavy metals, the plant is used as a
phytoremediation agent; its biomass can also be used biofuel production.
Objective: To compile information on state-of-the-art water treatment processes and biofuel production with E. crassipes to design an integrated biohydrogen and bioethanol production process with the plant’s biomass.
Materials and methods: The available literature on E. crassipes was reviewed to analyze the
designs and propose an integrated phytoremediation and bioenergy system.
Results and discussion: The proposed design can be adjusted to industrial scale conditions. This design includes a phytoremediation system, a bioreactor to generate hydrolysis, a bioreactor to generate bioethanol and, finally, a bioreactor to generate hydrogen.
Conclusions: By consulting the state of the art of the proposed designs, it is possible to
create and construct, on a large scale, a system for producing bioethanol and biohydrogen
from E. crassipes biomass (loaded or not with heavy metals). In this way, the plant biomass is not wasted as it is today.
Global concentration of MDF (Medium Density Fiberboard) exports
Concentración mundial de exportaciones de MDF (Medium Density Fiberboard)
Available online: 2019-07-11
/ pages 413-424
Introduction: Engineered for noble purposes, Medium Density Fiberboard (MDF) is a reconstituted wood panel used to reproduce wood designs and details.
Objective: To analyze the global concentration of MDF exports in the period 1995 to 2016.
Materials and methods: The information was obtained from the statistics division of the Food and Agriculture Organization of the United Nations (©FAO Statistics Division). Export concentration was measured using the following indicators: concentration ratio (CR[k]), Herfindahl–Hirschman index (HHI), Theil’s entropy index (E), comprehensive concentration index (CCI), Hall and Tideman index (HTI) and Gini coefficient (G).
Results and discussion: MDF exports grew 9.44 % annually, with China and Germany being the main exporters. The CR(k) indicated moderately low concentration, but with an oligopolistic market structure with high competition. competitiveness. Analysis of the indicators HHI, E, CCI and HTI indicate that there is low concentration and G infers strong inequality that tends to absolute.
Conclusion: Global MDF exports showed an oligopolistic market structure with high competition.
Specialization and competitiveness of natural rubber (Hevea brasiliensis [Willd. ex A. Juss.] Müll. Arg.) production in Mexico
Especialización y competitividad de la producción de hule (Hevea brasiliensis [Willd. ex A. Juss.] Müll. Arg.) en México
Available online: 2019-07-15
/ pages 425-439
Introduction: The dynamics and trade interaction between countries has led to transformations in their economic structures, and a process of productive specialization in the agricultural sector.
Objective: To analyze the behavior of natural rubber (Hevea brasiliensis [Willd. ex A. Juss.] Müll. Arg.) production and identify specialized and competitive regions using regional analysis techniques.
Materials and methods: Mexico’s states and municipalities were considered geographical
units. The methods of analysis were the location quotient, Shift-Share, specialization and
competitiveness. The value of natural rubber crop production, in the period 1980-2016, was
used as an analysis variable. The information was obtained from the Agrifood and Fisheries
Results and discussion: Results show increased natural rubber production and reconfiguration of its specialization. Tabasco is the most specialized state and Veracruz, Chiapas and Tabasco have competitive advantages; however, the states with the greatest prospects for growth and being highly specialized and competitive are Oaxaca and Tabasco. The specialization and competitiveness of natural rubber production is related to natural conditions, market demand and technological development.
Conclusions: Oaxaca and Tabasco have prospects for specialization and competitiveness, so natural rubber production should be expanded to these regions that in theory should be the most productive and with the lowest production costs. To exploit these advantages, it is necessary to promote
Forest rehabilitation and its role in bird conservation in El Porvenir, Hidalgo, Mexico
La rehabilitación forestal y su papel en la conservación avifaunística en El Porvenir, Hidalgo, México
Available online: 2019-07-26
/ pages 441-459
Introduction: Conserving terrestrial ecosystems in good condition is a global challenge. In Mexico, forest rehabilitation is a widely used practice to achieve this task.
Objective: To analyze the effect of forest rehabilitation on avifauna parameters (richness, abundance and diversity) and vegetation structure.
Materials and methods: The study was conducted in El Porvenir, Hidalgo, Mexico, in areas under forest rehabilitation with Pinus greggii Engelm. ex Parl. aged 5(R5), 12(R12) and 14(R14) years, and in a Pinus cembroides Zucc. forest as a reference site (RS). Sampling was done using a systematic grid design. Avifauna presence was monitored under two schemes: fixed-radius point counts and capture by constant-effort mist-netting. The tree structure was characterized by the point-centered quarter method. Differences between conditions were tested with a permutational multivariate analysis of variance (PERMANOVA).
Results and discussion: The RS had the highest bird richness (34) and showed significant differences (P = 0.0003) with rehabilitation conditions. The distribution of abundance in R5 and R14 was fitted to a geometric model, R12 to a logarithmic model and RS to a log-normal one, exhibiting significant differences among them (P = 0.033). Bird diversity presented differences between conditions (P = 0.005); the maximum similarity was between R14 and RS. The older the forest rehabilitation age, the more the vegetation structure and bird parameters increased.
Conclusion: The areas under forest rehabilitation function as reservoirs for the maintenance and conservation of avifauna in disturbed environments.
Effect of light and soil moisture on physiological variables in six Mediterranean forest species planted under a pine forest canopy
Efecto de la luz y la humedad del suelo sobre variables fisiológicas en seis especies forestales mediterráneas plantadas bajo dosel de pinar
Available online: 2019-07-23
/ pages 461-476
Introduction: Resprouter species, by regenerating rapidly, can maintain an optimal carbon balance and improve the resilience of ecosystems that have been disturbed or are at high risk of fire.
Objective: To assess the effect of light availability and soil moisture on the ecophysiological variables of six resprouter species planted under cover of Pinus halepensis Mill.
Materials and methods: Arbutus unedo L., Rhamnus alaternus L., Quercus ilex L., Quercus faginea Lam., Fraxinus ornus L. and Acer granatense Boiss. were planted in plots with three pine densities per hectare: HD = 800 to 1 100, MD = 300 to 600 and LD = 100 to 250. The species were also grown in the nursery, trying to maintain the same solar radiation conditions. Photosynthesis (A), stomatal conductance (Gs), photosystem II maximum efficiency (Fv/Fm) and water use efficiency (IWUE) were measured.
Results and discussion: Evergreen sclerophyll species (A. unedo, R. alaternus and Q. ilex) showed higher photosynthetic capacity, lower photoinhibition and lower IWUE than deciduous species. In HD, plants showed lower photosynthetic capacity (P < 0.01) and higher photoprotection (P < 0.001). The IWUE was similar under the three pine forest densities. In the nursery, A was high under 100 % and 50 % light conditions; Gs was higher under 20 % conditions; and IWUE was high under 100 % light.
Conclusion: The physiological variables of the species were conditioned by shading and changes in water demand produced by tree cover.