Introduction: Ectomycorrhiza and mycorrhiza helper bacteria are essential to the nutritional recycling of forest ecosystems. Objective: Growth, photosynthetic rate, chlorophylls, carotenes, root colonization and N, P and K contents were evaluated in Pinus montezumae plants inoculated with the edible ectomycorrhizal fungus Hebeloma mesophaeum (Hm), alone and in combination with the bacteria Cohnella sp. (C) or Azospirillum brasilense (Ab). Results and discussion: Plants inoculated only with the fungus or coinoculated with the fungus and the bacteria showed better physiological quality than the uninoculated plants and those inoculated exclusively with the bacteria, mainly in terms of growth, photosynthesis and nutrient content. Hm inoculation, alone or in combination with the bacteria, increased the chlorophyll a, b, and total concentrations. Bacterial inoculation increased the carotene concentration, while the fungus alone had no effect. There was synergism in the plants inoculated with Hm + Ab, which was reflected in shoot and total N contents, compared to plants inoculated with Hm or Ab separately. Ectomycorrhizal colonization ranged from 69 to 76 % in inoculated treatments. Conclusion: There is biotechnological potential for coinoculation with edible ectomycorrhizal fungi and mycorrhiza helper bacteria in P. montezumae.

Introduction: In northern Mexico, mesquite is widely used in reforestation. The production of quality plant is necessary for its establishment in the field.  Objective: To evaluate the effect of different moisture retainer doses, substrate mixtures and irrigation frequencies on growth of Prosopis laevigata. Materials and methods: The effect of five moisture retainer doses (0.0,1.5, 3.0, 4.5 and 6.0 g·L-1), two irrigation frequencies (every 48 and 96 h) and two substrate mixtures (base mixture [55 % peat moss + 24 % vermiculite + 21 % agrolite]) and composted bark [50 %] + peat moss [50 %]). Mesquite plants were evaluated at three months of age in a randomized block experimental design with a factorial arrangement.  Results and discussion: The factors, both individual and in interaction, caused significant differences (P < 0.05) in plant height, diameter and biomass. The best results were obtained using the base mixture, irrigation every 48 h and moisture retainers at doses of 1.5, 4.5 or 6.0 g·L-1. Substrate was the most influential factor. Conclusion: Growth of P. laevigata is favored through the most beneficial combination of substrate type, irrigation frequency and moisture retainer dose.

Introduction: Chest-height trunk diameter and height are the main variables measured in forestry inventories, as they aid in the decision-making process in forest plantation management and in research on growth modeling, among other uses. Objective: The aim was to find the mathematical function that best relates diameter at chest height (CHD, ≈1.3 m) to height (Ht) in three forest species grown within the same area: wild avocado (Cinnamomum sp.), Chiapas white pine (Pinus chiapensis [Martínez] Andresen) and piocho (Melia azedarach L.).  Materials and methods: Twenty-two non-linear models, of which thirteen had two parameters and nine had three parameters, were compared using the difference in Akaike’s information criterion corrected (AICc).  Results and discussion: The best models were: the two-parameter hyperbola for wild avocado (Ht = (17.58*CHD)/(12.33 + CHD), R2 = 0.79, SEE = 0.80, n = 647); the three-parameter Richards’ function for Chiapas white pine (Ht = 10.14*(1 – e-0.206*CHD)1.689, R2 = 0.35, SEE = 1.28,  n = 664); and the three-parameter sigmoid Korf’s function for piocho (Ht = 18.25*(e-2.46*(CHD-0.556)), R2 = 0.49, SEE = 0.96, n = 692).  Conclusion: The best model was different for each species and the actual data around the predicted curve were highly scattered, particularly in Chiapas white pine.

Introduction: Leucaena leucocephala (Lam.) de Wit is native to tropical America. The root system of the species is associated with microorganisms that improve nutrition and growth. Objective: To evaluate the effect of arbuscular mycorrhizal fungi (AMF) collections on the phosphorus (P) content and growth of L. leucocephala in the nursery. Materials and methods: The seeds were sown and six treatments were applied: Rhizophagus intraradices (Schenck & Sm.) Walker & Schüßler (1), the collections “Caracoles” (2), “Rosario Izapa” (3), “Té limón” (4) and “San Rafael” (5), fertilization 15N-15P-15K (6) and a control. Morphological and physiological variables, root colonization and P content were recorded at 120 days. Data were subjected to an analysis of variance and Tukey’s range test (P ≤ 0.05). Results and discussion: AMF improved plant characteristics in comparison with the control and fertilization. Rhizophagus intraradices caused the highest growth values in the aerial part, mycorrhizal colonization and P content, and the lowest growth in the root system. The “Caracoles” and “Rosario Izapa” isolates promoted height, root biomass and P content higher than “Té limón” and “San Rafael”. Conclusion: AMF allow decreasing chemical fertilization without detriment to the growth of L. leucocephala.

Introduction: The dynamics of land use and changes in vegetation cover is essential for natural resource management. Objetive: To analyze the land use change in the micro-watersed of Zoquiapan, between 1989 and 2009, and to estimate the change trend for the year 2020. Materials and methods: Two satellite images (March 21, 2009 and March 7, 1989) were taken, corresponding to the Landsat sensor, and were processed using the software IDRISI©. The classes studied were forest, grassland and agricultural use. The Márkov-Markovian transition estimator command was applied to estimate the stationary vector of the chain between the years of study and to know the future trends of vegetation cover. Results and discussion: Between 1989 and 2009, the agricultural and grassland area decreased 1.86 and 88.63 ha, respectively; the forest area increased 90.5 ha. By 2020, the micro-watershed of Zoquiapan will have a low probability of change. The probabilities of permanence are 94 % for forest, 88 % for grassland and 91 % for agricultural activities. Conclusion: The micro-watershed of Zoquiapan has not had any significant land use change. The areas covered by forests have a low probability of change, as long as the conservation efforts carried out so far continue.

Introduction: Stand density affects productivity and the structure and functions of forests.Objectives: To compare maximum density lines for mixed-species forests adjusted with Ordinary least Squares (OLS) and Stochastic Frontier Regression (SFR); and generate a density management diagram (DMD) to prescribe thinning.Materials and methods: The data was obtained in mixed-species stands from the Forest Management Unit 1005 “Santiago Papasquiaro y Anexos” in Durango, Mexico. The density-size relationship was established using the Reineke’s model. The maximum density line was adjusted with OLS and SFR, the latter with the half-normal (H-N), normal-exponential (N-E) and normal-truncated (N-T) approaches. The DMD was constructed with the SFR equation with the normal-truncated distribution approach.Results and discussion: The maximum density line, modeled through SFR with N-T approach showed better fit to the upper limit of the maximum density of the mixed-species stand data. DMD suggests that thinning for these stands can be applied with high cutting intensities, contrary to conventional practices, where rarely more than 30 % of the basal area or volume is cut.Conclusion: The maximum density line for mixed-species forests in Durango, Mexico, was generated with stochastic frontier regression, as a normal-truncated model.

Introduction: The morpho-anatomical study of seeds and their embryos serves to obtain information on germination, storage and viability.  Objective: To describe the morphoanatomy of the embryo of the palm species Acrocomia aculeata (Jacq.) Lodd. ex Mart., at the cellular level. Materials and methods: The embryos were obtained from mature fruits of A. aculeata, collected in individuals of a native population near the city of San Lorenzo, Central Department, Paraguay. The morpho-anatomical study was done by means of the fixation, dehydration and inclusion of the embryos in resin blocks and qualitative analysis by means of microscopy. Results and discussion: The embryo is small, greenish yellow and lanceolate. The cotyledon is located at the proximal end, and the limbus or haustorium in the distal. The embryo has a longitudinal slit or cotyledon window that allows the emergence of the seedling (radicle and plumule). The well-differentiated plumule is positioned at an angle with respect to the longitudinal axis of the embryo, opposite to which is the meristematic zone, where the radicle will develop. The plumule consists of two leaf primordia and one apex, with the outline of a third primordium. Conclusion: In general, the A. aculeata embryo is similar to that of other palms of the same group, in terms of shape and inclusion in the endosperm.

Introduction: The cellular characteristics of wood determine the conditions of processing and use of forest species Objective: To study the variation of the anatomical characteristics in the internal and external part of the heartwood of Tectona grandis L. f. with different ages and origins. Materials and methods: Trees from Campeche (9 and 15 years old), Tabasco (15 years old) and Chiapas (21 years old) were selected. Cuttings (10 and 20 μm thick) of the anatomical faces (transversal, radial and tangential) of the wood were made and were observed using a clear field microscope. The images were captured with Matrox PC-VCR version 02.10.10. The cellular elements were measured using the ArcView GIS 3.2. Results and discussion: Teak wood had 6 to 8 vessels·mm-.. Wood (9 and 15 years old) from Campeche had the largest vessels diameter on the inside and outside of the heartwood; in its internal part, it had the largest ray width. In both parts of the heartwood, 9-year-old-wood from Campeche had higher ray height; 21-year-old wood from Chiapas had greater length and diameter of fibers; and 15-year-old wood from Tabasco produced the largest wall thickness of fibers. Conclusions: Age and origin affect the cellular structure of teak wood.

Introduction: Nutrient cycle studies are important to propose sustainable methods in forestry. Objectives: To evaluate the reservoirs of N, P, K, Ca and Mg in trees, litter and mineral soil of two managed stands of Pinus montezumae Lamb.; estimate the decomposition rate of litter; and quantify the annual amount of nutrients required for tree growth. Materials and methods: The study was conducted in Nanacamilpa, Tlaxcala. The biomass and mass of nutrients in trunk, branches and leaves were estimated with a destructive sampling of 10 trees. Results and discussion: Dasometric data, reservoirs and nutrient dynamics were similar in both stands (t, P > 0.05). In mineral soil, the contents of N, P, K, Ca and Mg were 5 419, 68, 1 245, 9 163 and 2 029 kg·ha-1, respectively; and in aerial biomass were 242, 12, 28, 167 and  118 kg·ha-1, respectively. The decomposition rate of leaf-litter was -0.335. Trees require 73 to 81 kg·ha-1·year-1 of N, 5.2 to 5.3 kg·ha-1·year-1 of P and 9.4 to 10 kg·ha-1·year-1 of K to grow.  Conclusion: Soil nutrients could maintain forest growth for 256 years, but P could be a limiting factor if sustainable harvest practices change.