Deforestation in Mexico has made restoration an urgent requirement. Erythrinaamericana is a multipurpose tree, useful for seasonally dry tropical forest restoration;however, it is poorly studied. Macropropagation of this species is advantageouswhen compared with sexual reproduction, since it requires scarification to germinate. Inthis study, the effects of the exogenous application of the phytohormone (indole-3-butyricacid) in the cuttings and/or a slow-release phosphate fertilizer (SRPF) in the substrate wereevaluated on the growth and survival of E. americana cuttings in a greenhouse. We used arandomized experimental design of four blocks with 10 cuttings per treatment. We harvested10 cuttings per treatment after 36, 66, 96 and 126 days of growth, and evaluated survival,total dry biomass production (TDB), relative growth rate (RGR), and resource allocation (RA).Cutting survival was high, averaging 95 %. Treatments did not affect total TDB, RGR or RA.However, the application of SRPF in the substrate showed significantly higher (P < 0.05)dry root biomass values. Growth periods also affect the RGR and RA. Macropropagationof E. americana was successful and non-labor-intensive, making this technique a feasiblealternative for restoration projects mainly in low-resource rural communities.

Necrosis and morphogenic response of cotyledon, epicotyl and hypocotyl explants of Lupinus montanus (HBK) seedlings germinated in vitro were evaluated to establish the basic conditions of micropropagation. Necrosis was evaluated in MS medium with 0.40 mg·liter-1 thiamine, 100 mg·liter-1 myo-inositol, 3 % sucrose and 7 g·liter-1 agar-agar and different doses of activated carbon (AC) and citric acid. Treatments with AC (50 mg·liter-1 and 100 mg·liter-1) were the best in the control of necrosis (P = 0.001); the cotyledon had a higher level of necrosis (< 60 %) than the epicotyl and hypocotyl (10 to 30 %). Morphogenic responses were analyzed on MS medium with 0.40 mg·liter-1 thiamine, 100 mg·liter-1 myo-inositol, 3 % sucrose, 7 g·liter-1 agar-agar, 100 mg·liter-1 AC and five combinations of IAA (indole acetic acid) and BA (6-benzyladenine). The hypocotyl and epicotyl explants showed higher organogenic response (> 70 %), whereas the cotyledon response was primarily callogenic (50 %). The epicotyl cultured on MS medium with 3.0 μM IAA and 1.0 μM BA had the highest number of shoots (10) and height thereof (11.4 ±2.6 cm).

The aim of this study was to determine the concentration and amount of nitrates (NO3 -), ammonium (NH4 +) and mineral nitrogen (Nmin = NO3 - + NH4 +) in precipitation and runoff in six plots in Texcoco, State of Mexico, during the rainy season of 2001 and 2010. For this purpose, six runoff plots with corn cultivation were prepared, three with conventional management (CM) and three with organic management (OM). From 2001 to 2010, average concentrations of NO3 -, NH4 + and Nmin in precipitation increased to 1.307, 0.833 and 2.140 mg·L-1, respectively. Minimum values of NO3 -, NH4 + and Nmin also increased to 0.550, 0.970 and 1.640 mg·L-1, respectively. In runoff, average concentrations of NO3 - in 2001 and 2010 were higher with CM, while concentrations of NH4 + were smaller. Because Texcoco´s population increased by 31,049 from 2001 to 2010, we concluded that population growth and development of the area had an effect on the amounts of nitrogen in precipitation, and that OM was an alternative to reduce nitrogen outputs by runoff.

Arsenic is one of the most toxic metalloids present in the environment and prolonged exposure to this metal causes chronic health effects. Therefore, the search for environmentally-friendly alternatives for the treatment of arsenic-contaminated water and soil is important. In this study, bacterial strains were isolated from arseniccontaining soils in the Lagunera region to analyze those with arsenite-oxidizing abiliity. Strains 04-SP1qa and 14-SP1qh with chemolithoautotrophic and chemoheterotrophic metabolism, respectively, had greater activity of the arsenite oxidase enzyme. The optimum growth conditions and enzymatic activity of these strains were investigated. Strain 04-SP1qa had specific enzymatic activity of 0.162 μmol·min-1·mg-1, Michaelis-Menten constant (Km) of 3.37 μM and maximum velocity (Vmax) of 5.2 μM·min-1·mg-1 under optimum growth conditions of pH 8.0 at 40 °C. Strain 14-SP1qh showed specific enzymatic activity of 0.16 μmol·min-1·mg-1, Km of 3.7 μM and Vmax of 14.39 μM·min-1·mg-1 at pH 7.0 and 40 °C. Results of this study demonstrated the presence of arsenite- oxidizing bacteria with enzymatic activity in the soils of the Lagunera region. Thus, the potential exists to develop new bioremediation technologies for treatment of arsenic-contaminated water and soils in the region using native bacterial strains.

Most dendrochronological studies are based on the relationship between total radial growth and precipitation; however, very few studies have considered the responses of early (EW) and late (LW) wood growth or the role of evaporation. In this study, residual indices for forests in the state of Durango (Mexico) during the period 1964-2010 were used to evaluate the response of EW and LW growth in Pinus cooperi Blanco to evaporation. DENDROCLIM software was used to correlate dendrochronological data to total monthly evaporation. Evaporation from January of the previous year to December of the current year was considered in a simple interval analysis. The coefficients of correlation indicated a consistent negative relationship between both EW and LW growth and evaporation in the fall/winter prior to the growth season. Nevertheless, LW growth was more consistent in terms of climatic sensitivity, which may indicate that measurement of this parameter may be more useful in dendroclimatic studies.

The structure and diversity of pine-oak woodlands in Ixtlán de Juárez, Oaxaca, was analyzed using three sampling units (SU) of 50 x 50 m. The spatial distribution of trees with normal diameter ≥ 2.5 cm was determined. Dasometric variables were recorded; two indices of structural importance (the Relative Importance Value Index [RIVI] and the forest value index [FVI], and three diversity indices (Shannon-Wiener Entropy Index, effective number of diversity, and Sorensen index) were calculated. A total of 799 trees were recorded, belonging to 11 families and 19 species; the most abundant family was Fagaceae (628 individuals, four species). In SU1, the most important species was Quercus crassifolia (RIVI = 53; FVI = 57). The highest values of RIVI and FVI in SU2 were for Q. laurina (RIVI = 48, FVI = 63). In SU3, the most important species was Q. crassifolia (RIVI = 49, FVI = 62). The analysis of both species revealed random distribution in practically all distances. The aggregate pattern of tree species was attributed to regeneration strategies and silvicultural practices. Both species can coexist modifying the structural importance and horizontal distribution pattern. ment of arsenic-contaminated water and soils in the region using native bacterial strains

The effect of substrate, type of cutting and indole 3-butyric acid (IBA) concentration on the rooting of Pinus leiophylla cuttings was evaluated with the goal of multiplying progenies of half-sib families of this species, which have showed superior growth and positive response against Toumeyella pinicola attack. Two types of substrates (100 % perlite vs. a mix of peat, perlite, vermiculite at a ratio of 1:1:1), two types of cuttings (apical vs. basal) and two concentrations of IBA (0 vs. 10,000 ppm) were used. Probability and percentage of rooting, growth of cuttings and characteristics of the roots were evaluated. Results indicate that using basal cuttings is 3.5 times more likely to induce rooting of P. leiophylla than using apical cuttings. The treatment consisting of the mixture of peat-perlite-vermiculite, a basal cutting and 10,000 ppm of IBA produced 45.3 % rooting (highest percentage), while the control only yielded 8.6 % rooting (perlite, basal cutting and without IBA). Interactions with the type of substrate showed significant differences (P ≤ 0.05) in the growth of the cuttings. The use of perlite and application of IBA promoted a greater number of roots, particularly in the basal cuttings of P. leiophylla.

The aim of this study was to determine the site quality of juniper (Juniperus deppeana Steud.) in the San Dimas region of the state of Durango, Mexico, using the site index method. The database comes from stem analysis of 43 trees felled in harvesting activities. The Chapman-Richards and Schumacher models, by means of the algebraic difference and generalized algebraic difference approaches, were tested to determine the site index; in addition, the error structure was modeled with a second-order autoregressive model to remedy the dependency of existing longitudinal errors. The results showed that the Chapman-Richards model in generalized algebraic difference form provided the best fit according to the adjusted coefficient of determination (R2 adj = 0.98) and root mean square error (RMSE = 0.46 m). Plotting of the quality curves generated with this model, superimposed on the observed heights, corroborated the goodness of fit of the model selected. The equation obtained with the generalized algebraic difference approach directly estimates the dominant height and site index at any height and base age.

In the present study, the effect of silvicultural practices on richness, composition and diversity of tree species, herbaceous and shrub species in a forest community of Santa Catarina Ixtepeji, Oaxaca was evaluated. To this end, the following silvicultural treatments were evaluated: selective cutting (1998), light thinning (2011) and seed tree cutting (1998 and 2011). Alpha and beta diversity indices of tree communities (shrub and herbaceous) were estimated, and also the Importance Value index (IVI) of the tree layer. The results showed that the herbaceous component is the most diverse in both stands with and without silvicultural management, followed by the shrub component. According to the IVI, Pinus oaxacana Mirov was the most important ecological species in all treatments evaluated, including unmanaged forest. The results indicate that logging modifies richness, diversity and composition of the tree strata (shrub and herbaceous), these two tree strata are the largest contributors to diversity. Therefore it is important to assess the understory, because it helps giving a better explanation of the total plant diversity of the forest.

The insect Trioza rusellae Tuthill (Hemiptera-Triozidae) produces galls on the leaves of the Ramon (Brosimum alicastrum Swartz) tree, species with high nutritional value of the Peninsula of Yucatan. The insect was isolated and identified from collections in the municipalities of Muna and Sacalum, Yucatán. Five to 10 years old trees were sampled selecting branches with leaves showing galls. The samples were placed in plastic bags and taken to the laboratory, and placed in entomological cages. Adult insects were collected using a manual vacuum, while galls were dissected to collect the nymphs directly with a brush (0001). The samples were preserved in alcohol (70 %) and in fixative formalin-alcohol-water (FAW). Nymphs and adult insects from the alcohol samples were mounted and observed on a stereoscopic microscope. The samples in FAW were processed and observed under a scanning electron microscope (SEM). As a result, photographs were obtained and development phases of T. rusellae were identified by entomological keys.