This paper compares three methods to obtain synthetic unit hydrographs (SUH).The Snyder (modified for Chile by Astorga and Benítez), the US Bureau of Reclamation, and the Témez methods are analyzed on two watersheds located in Mediterranean areas of Chile. To do so, each watershed was characterized in terms of its morphology and vegetation type. In addition, data from three actual storms, with high, medium, and low rainfall intensities, were used to obtain direct runoff hydrographs (DRH) for both watersheds. The NRCS Curve Number method was used to estimate runoff responses to storm events. Our results suggest that, in general, the SUH used had no significant differences between watersheds. On the other hand, the Snyder SUH method was the only one that found significant differences in the DRHs relative to the other methods and only under a high-intensity storm in the Cunculén watershed.

This study provides an economic evaluation of the response to planting densities and spacing patterns in Eucalyptus globulus planted for pulping. The Monte Carlo technique was used to examine the effect of price variations and the discount rate on profitability. The trial was carried out in the Central Valley of the IX Region of Chile. The treatments (T) were: 1,000 trees·ha−1 (T1); 1,428 trees· ha−1 (T2); 1,667 trees·ha−1 (T3); and 2,000 trees·ha−1 (T4). The production volume of each treatment was measured at harvest age (10 years), and then a financial analysis was made to obtain the profitability (present net value, PNV; economic land value, ELV; and internal rate of return, IRR). The highest PNV values were obtained with T1 (330 US$·ha−1) and T4 (322 US$·ha−1). The predictions obtained for the PNV of T1 showed a probable occurrence of 73 %, making it the least risky investment option. Higher volumetric yields (T4 and T3) do not lead to higher profitability, since the increase in planting density leads to an increase in the unit cost per plant for land management, weed control and fertilization.

In order to know to what extent the severity of a fire modifies the structural parameters of a stand, the objective of this research was to conduct an exploratory analysis of the spatial distribution of trees present in mixed conifer stands of the Sierra Madre Oriental, affected by fire during the summer of 1998. The selected area consisted of three mixed conifer stands with three different fire severity levels (low, medium and high). We analyzed the distribution patterns of trees through the Ripley’s K function; likewise, we analyzed the spatial interaction of trees in relation to their size and species through a mark correlation function (MCF) k_mm(r) . It was observed that according to an increasing fire severity, the spatial distribution of trees tend to aggregate and to maintained the formation of stands dimensionally heterogeneous, however tree species composition was no affected significantly. The influence of fire in these forests was observed as a promoter of dimensional diversity, although spatial mixing of species had a tendency to homogeneity

Heliopsis longipes is a perennial herb endemic to Sierra de Álvarez and Sierra Gorda in central México. It is a species of major economic importance within its genus, due to the traditional uses of its root. Chemical and pharmacological studies have been performed with H. longipes roots, however recent studies regarding its distribution are lacking. The objective of the current study was to establish and document the geographic distribution and existing ecologic conditions of H. longipes. A review of published works regarding this species, as well as an examination of herbarium specimens has been conducted. Explorations in Sierra de Álvarez and Sierra Gorda were also conducted to locate populations of H. longipes. In each site, the physical and biological factors associated with the population were recorded. Heliopsis. longipes is distributed in the states of San Luis Potosí, Guanajuato and Querétaro, in steep canyons with oak and oak-pine forests and substrates of igneous origin, in Sierra de Álvarez and Sierra Gorda.

The effect of vermicompost, as part of the growth substrate, on the development of huizache (Acacia farnesiana) seedlings placed under a rustic shelter made from reeds was evaluated over a period of 240 days. Five vermicompost-sand mixtures with five ratios, namely 10:90, 20:80, 30:70, 40:60 and 50:50 (% by volume), were assessed, and natural soil from the area where huizaches grow was used as the control. Seeds for producing the seedlings were obtained from the huizaches of the area. The treatments were replicated 30 times, and five seedlings were harvested from each one to determine plant height, main stem diameter, number of branches, and fresh and dry weight. The effect of the treatments was determined using a completely randomized experimental design and the averages were compared by the LSD5 % test. Huitzache growth was not uniform in the different substrates; however, the 10:90 vermicompost-sand mixture had the best variable responses in terms of plant height and fresh and dry weight. Therefore, vermicompost at low concentration promoted the growth of A. farnesiana.

Prostephanus truncatus (Horn) is a wood borer insect adapted to stored food products, mainly maize. In this study we quantified losses and damages caused by this insect in 10 varieties of maize and 10 plant species to determine the susceptibility and effects that the insect could provoke if it adapts to the conditions in northwestern Mexico. Maize seeds and pieces of branches of tree species were subjected to artificial infestation by adult P. truncates, and then incubated at 27 ± 1 °C and 70 ± 3 % RH. The preference of insects and damage in each material were determined. Insects preferred and damaged most to “Maizon”, a variety of native maize planted by producers of the mountainous region of Sonora. The pieces of branches with higher degree of damage by P. truncatus were Ricinus communis, Jatropha cardiophylla and Parkinsonia aculeata; however, the insect was unable to reproduce in any of the branches. “Maizón” was also the variety that had the most dramatic decline in germination and the highest number of adults of P. truncatus emerged.

The forest industry in the municipal seat of Nuevo San Juan Parangaricutiro and the Indigenous Community of Nuevo San Juan Parangaricutiro, located in Michoacán state, Mexico, generates 1,232 m3·year-1 of underutilized pine sawdust and shavings. The sawdust and shavings of Pinus leiophylla Sch. Et Cham., P. montezumae Lamb. and P. pseudostrobus Lindl were subjected to physicochemical analyzes to determine if they meet the requirements for pellet and briquette production. The moisture, ash, and inorganic element contents in the byproducts were determined using international standards. Moisture content in ash was 51.5 ± 1.9 %, and 53.7 ± 0.1 % in shavings; these values exceeded the maximum allowable. Ash content in sawdust and shavings was 0.26 ± 0.03 % and 0.34 ± 0.03 %, respectively. For the three species evaluated, the average percentage of calcium, potassium, magnesium, phosphorus, sulfur, silicon, iron, aluminum and sodium in sawdust was 47.1 ± 2.8, 26.0 ± 2.5, 13.5 ± 0.4, 5.0 ± 0.4, 3.2 ± 0.4, 2.3 ± 0.8, 1.0 ± 0.1, 1.3 ± 0.4 and 1.4 ± 0.3, respectively, while the average percentage was 43.2 ± 7.0, 16.5 ± 3.0, 10.1 ± 4.8, 4.0 ± 0.6, 1.8 ± 0.2, 3.6 ± 0.3, 1.0 ± 0.6, 1.1 ± 0.1 and 1.0 ± 0.6 in shavings, respectively. Arsenic was only found in the shavings (17.1 ± 17.1). Based on the results, sawdust is the most suitable byproduct for pellet and briquette production.

The use of wastewater in irrigation of forage crops is a practice that increases daily in areas where water, for this purpose, is scarce. However, growers, when being in direct contact with wastewater, suffer from gastrointestinal diseases caused by coliforms and parasites (helminths). In the present study, we evaluated fecal coliform (in wastewater, soil and plants) and helminths (in wastewater) in module II, Irrigation District 028, Tulancingo, Hidalgo. Bacteriological and helminth analyzes were consistent with the methodologies reported in the NMX-AA-003-1980, NOM-001-SEMARNAT-1996, PROY NMX-AA-042-SCFI-2008 and section 9810 APHA. A total 16 water sampling sites were determined in irrigation channels and 54 samples of both soil and plants were taken. The highest fecal coliform concentrations were 2 x 1010 MPN·100 mL-1 of water, 109 MPN·100 g-1 of soil, 109 MPN·100 g-1 of root and 3 x 109 MPN·100 g-1 of stem. Eleven of the 16 sampling sites were helminths. We suggest treating wastewater before use, to prevent health problems among growers.

The mycelial growth rates of ectomycorrhizal fungi Suillus granulatus and S. brevipes were assessed in three culture media (PDA, BAF and MMN) at two pH values (4.8 and 5.8) in order to select the best culture medium. The strains were isolated from sporocarps collected in a Pinus hartwegii forest in Cofre de Perote National Park, Veracruz, Mexico. Significant differences (Tukey, P ≤ 0.05) in the growth area of both species were found. The highest values were recorded in the PDA medium. Concerning the pH values tested, there were no significant differences. Each of the tested media can be used for culturing the S. granulatus and S. brevipes strains, depending on the objectives. The PDA medium was the best substrate for the growth of the strains. We suggest using the BAF medium for mass production of mycelium for inoculum, and the MMN medium for either strain maintenance or mycorrhization testing.

We collected leaves from the Psittacanthus calyculatus hemiparasitic plant and Salix taxifolia, Ulmus divaricate, Fraxinus uhdei y Prosopis laevigata host trees, to understand and compare the contents of Mg, Al, Si, P, S, K, Ca, chlorophyll and protein. Analyses were performed with a scanning electron microscope (SEM) equipped with an energy dispersive X-ray spectrometer (EDS). The results showed that the hemiparasitic plant accumulated (at least twice) more K compared to its host trees, indicating that the hemiparasitic plant use an active mechanism to achieve this accumulation. According to the statistical analysis (P = 0.05), U. divaricate is the species that accumulates more S, Si and Ca. Mg content was also higher in U. divaricate, but was statistically similar (P = 0.05) than in the hemiparasitic plant. P content was similar (P = 0.05) in both P. calyculatus and their host trees. Fraxinus uhdei accumulated more C than the rest of the species. Chlorophyll content was higher in F. uhdei and S. taxifolia, while P. laevigata had the lowest content. P. calyculatus leaves had high protein content (21 %).

The structure and diversity of a semi-evergreen tropical forest in the Andrés Quintana Roo ejido, located in the municipality of Felipe Carrillo Puerto, Quintana Roo, Mexico, was analyzed. To this end, six sampling units of 20 x 50 m (1,000 m2), two units per tropical forest development condition (age of disturbance), were established: a) forest fire 10 years ago (C10), b) agricultural use 24 years ago (C20) and c) pastoral use 33 years ago (C30). Forest structure was characterized by the diameter and height distribution of individuals in each condition, as well as using the importance value (IVI) and forest value (FVI) indices. Pouteria reticulata was the species with the highest IVI and Ficus sp. had the highest FVI, both in C10 and C20, while Bursera simaruba and Lysiloma latisiliquum obtained the highest IVI and FVI, respectively, in C30. Species diversity was evaluated using proportional abundance (Shannon: H’) and floristic similarity (Sorensen: IS) indices. Species diversity of seedlings, poles and saplings was higher in C10, C30 and C20, respectively. Poles had on average floristic similarities of 60 % between forest development conditions, while seedlings and saplings had less than 50 %.

In the community of San Pablito in the Sierra Norte de Puebla, Trema micrantha (known in Mexico as jonote) generates 80 % of the bark used to produce one of the most important and well known Mexican handicrafts: amate paper. Most community members are involved in this economic activity; however, bark supply is irregular and inadequate and comes from far away. This study has three objectives: evaluate the interest of people from neighboring communities to increase the production of jonote, document the silvicultural practices and evaluate the growth rate (tree height and diameter). Out of 28 farmers interviewed 40 % were interested in increasing jonote production and 20 % use silvicultural practices such as pruning, elimination of shade, transplanting and adding organic matter. Based on the measurements of 396 trees of estimated age, this species can obtain an average diameter of 7 cm after one year and 16 cm after 5 years. The best growth was observed on sites with slopes less than 70 %, altitudes between 1,200-1,600 m, fertile soils and direct light. Recibido

Hefei Round-the-City Park has typical urban forest characteristics. This paper uses vegetation ecology methods to analyze the community structure of the park, and species composition, tree-height distribution and DBH (diameter at breast height) were described. There are 27,662 trees in the study area, which has an urban forest area of 42.5 hm2. The average DBH was 19.2 cm, stand density was 651 trees·hm2 and average basal area was 20.8 m2·hm-2. Based on a health assessment, the trees in the park are in generally good health, as the healthy trees in the urban forest in the park accounted for 53.4 % of the total number. Through calculation of tree growth index and association correlation of component species in the park, the community structures were analyzed. The results show that community structures in the park are complex; there are 22 pairs of species with positive association and individuals in the following communities grow well and are more stable, including mainly Platycladus orientalis-Prunus cerasifera f., atropurpurea-Osmanthus fragrans, Robinia pseudoacacia-Ligustrum lucidum, R. pseudoacacia-Ginkgo biloba-Photinia serrulata, Populus canadensis-L. lucidum-O. fragrans, Sophora japonica-L. lucidum-Buxus sinica, Cyclobalanopsis glauca-Distylium racemosum.