Introduction

To strengthen production chains in the state of Chihuahua, it is necessary to evaluate the feasibility of establishing sawmills in forest communities and ejidos.

Objective

To formulate a sawmill investment project for the Basihuare ejido, Guachochi, Chihuahua, and to evaluate its viability by estimating financial and economic indicators.

Materials and methods

Projections of supply from 2020 to 2024 were made based on the records of roundwood inputs of the Pinus genus from 2015 to 2019. Sawmilling coefficients, sawn timber grade distribution and market price were determined with historical information from a private industry located in Guachochi. Feasibility was evaluated by estimating the income tax established according to income.

Results and discussion

A net present value of 16 194 605 MXN at a discount rate of 12 %, an internal rate of return of 78.69 % and a benefit/cost relationship of 1.25 were estimated. A break-even point of 1 520 255 bf produced, a payback period of 2.07 years and an economic profitability of 61.14 % were also determined.

Conclusion

The indicators were positive in all cases, which shows that the project is financially viable. The methodology used for the formulation and evaluation of investment projects in the forestry sector can be replicated and adapted by different agrarian nuclei.

Introduction

Metals are found naturally in the environment, but their indiscriminate use has caused serious pollution problems.

Objective

Two species of Aspergillus were isolated and identified from tailings, then their tolerance index at different concentrations of several metals was evaluated.

Materials and methods

Fungi were isolated from tailings located in the Sonoran Desert. Fungal growth was evaluated in the presence of Cr⁶⁺, Pb²⁺, Zn²⁺, Ag⁺, Cd²⁺, Cu²⁺ and Hg²⁺ metals using the tolerance index and minimum inhibitory concentration (MIC).

Results and discussion

A. flavus had very high tolerance indices to Cr⁶⁺, Pb²⁺ and Zn²⁺ at all concentrations evaluated (≥20 mM); it also had a high tolerance index to the other metals at lower concentrations. The MIC for this fungus in the presence of Cd²⁺, Hg²⁺ and Ag⁺ was recorded between 5 and 10 mM. The growth of A. nidulans was not inhibited with 20 mM of Cr⁶⁺. The MIC of A. nidulans in presence of Hg²⁺, Ag⁺ and Cu²⁺ is in the range 1-5 mM; with Cd²⁺, Pb²⁺ and Zn²⁺ it is in the range between 15 and 20 mM. The dose-response curves display a characteristic sigmoidal shape. With Ag⁺ and Cu²⁺ A. flavus displayed a hermetic behavior.

Conclusion

High metal tolerance of these fungi suggests their potential use in the removal of metals.

Introduction

The Abies forest of the Monarch Butterfly Biosphere Reserve (MBBR) is a key ecosystem for the butterfly Danaus plexippus L. The study of this habitat is essential to understand the global effects of environmental transformation.

Objectives

To study the impact of climate change over the last 20 years (2000-2019) on the MBBR, to (1) describe variations in climate and phenology; (2) analyze the relationships between LAI (leaf area index) and climate; and (3) estimate greening

Materials and methods

Monthly mean temperature and precipitation values from the NASA Giovanni database and the Copernicus LAI series were analyzed. Using the TIMESAT algorithm, 11 phenological variables per pixel and year were determined and the annual spatial average of each one was calculated for each type of land cover (pine, oyamel, shrubs and crops) and the cumulative increase of the extended integral (greening).

Results and discussion

Mean temperature increased 0.87 °C in 2000-2019. Beginning, middle, and end of the season have occurred progressively earlier, and cumulative leaf area, as well as minimum and maximum LAI, have increased. Greening was recorded in 53.21 % of the MBBR and browning in 33.97 %.

Conclusion

The increase in mean temperature affects phenology of MBBR, causing longer growing seasons and net greening of the area.

Introduction

Grafted plants of conifers are used in the establishment of clonal seed orchards, but with the methodology currently used, unsatisfactory results are reported.

Objective

To compare grafting and growth of Pinus greggii var. australis scion from nursery and field stock plants grafted on four rootstocks.

Materials and methods

Scions of P. greggii Engelm. var. australis Donahue et López, collected from nursery stock plants (NSSP) and field trees (FSSP), were divided into terminal bud and basal segment, and grafted onto P. greggii var. australis, P. patula Schiede ex Schltdl. et Cham., P. teocote Schiede ex Schltdl. et Cham. and P. leiophylla Schiede ex Schltdl. et Cham. Percentage of grafting, height increment, diameter, scion-rootstock ratio and number of shoots (NS) were evaluated. Height and diameter increment data were subjected to an ANOVA and NS was analyzed with Poisson regression.

Results and discussion

Grafting ranged from 93 to 100 %. The greatest increase in height was reported for P. teocote (14 cm) with scion from the terminal shoot of the nursery plant, while the combination P. greggii/P. leiophylla had the best scion-rootstock ratio with a value of 1. The highest NS was recorded with scion from the basal segment of NSSP. Getting two types of scions from one scion made the use of vegetative material more efficient.

Conclusions

The use of nursery stock plants, 15-month-old rootstock, and two types of scions allowed having grafted plants in three months. The methodology developed was efficient, cost-effective and fast.

Introduction

Arctostaphylos pungens Kunt is a species with significant characteristics for restoration; however, there are few studies on its propagation.

Objective

To evaluate the effect of pre-germinative treatments and the use of vegetative propagation methods in A. pungens.

Materials and methods

Eight pre-germinative treatments were evaluated, consisting of scarification with H₂SO₄ (98 %) for 5 and 6 h, gibberellic acid immersion (1 000 ppm), cold stratification (4 °C for 30, 60 and 90 days) and heat shock (100 °C for 5 min), as well as combinations of these. Vegetative propagation was analyzed by cuttings and air layering.

Results and discussion

The highest germination (73.33 ± 15.63 %) was for immersion in H₂SO₄ for 5 to 6 h; heat shock and cold stratification treatments showed low or no germination. Root formation was not achieved in cuttings but was achieved in 37.50 ± 25 % of 20-week air layering.

Conclusion

The best treatments consisted of immersion in H₂SO₄. It is recommended to continue experimenting with vegetative propagation by leaving air layering for more than the 20 weeks used in this study to achieve complete root development.

Introduction

Nutrient movement in high mountain forests generates information on their functioning and response to climate change effects. Nitrogen dynamics in these ecosystems has been poorly studied.

Objective

To quantify N reservoirs in forest litter, topsoil (0-10 cm) and needle litterfall, and to measure temporal concentrations of nitrate and ammonium in topsoil and N resorption (ReabsN) in the Jocotilán (JO) and Tláloc (TL) mountains of central Mexico.

Materials and methods

A total of 108 (JO) and 128 (TL) soil and needle litterfall samples were collected for one year. N and ReabsN reservoirs were compared between mountains using the Wilcoxon test (P < 0.05). Temporal trends of soil moisture, N and ReabsN forms were analyzed with linear mixed models, setting time and mountain as fixed factors.

Results and discussion

Gravimetric moisture, total N, and nitrate and ammonium concentrations were not different between mountains. Total inorganic N (ammonium + nitrate) in JO was higher than in TL (46 vs. 41 mg∙kg^-1). N in needle litterfall and soil were higher in JO, but ReabsN in TL was higher (60 vs. 55 %). Soil moisture, ammonium and ReabsN had a seasonal pattern of cubic trend (P < 0.05), denoting N pulses.

Conclusions

Forests showed differences in N dynamics in needle litterfall, resorption and soil inorganic forms of N, indicating that it is possible to differentiate their functioning according to this nutrient.

Introduction

Climate change represents a problem that generates long-term impacts and is considered a threat to the conservation of many species.

Objective

To evaluate the impact of climate change on the distribution areas of 10 trees species characteristic of cloud forests in the state of Oaxaca.

Materials and methods

The impact was evaluated for two-time horizons (2050 and 2080) and two emission scenarios (RCP 4.5 and 8.5) under the Had GEM2-ES general atmospheric circulation model. Current and future distribution was modeled with MaxEnt. The distribution of Carpinus tropicalis, Juglans pyriformis, Liquidambar styraciflua, Litsea glaucescens, Magnolia dealbata, Magnolia schiedeana, Ostrya virginiana, Symplocos coccinea, Zinowiewia concinna and Taxus globosa were obtained from the herbarium specimen review.

Results and discussion

In RCP 4.5, J. pyriformis, L. styraciflua, L. glaucescens and S. coccinea increased (2.8 % to 20.5 %) their area of distribution. In this scenario, the rest of the species reduced their area by up to 30 % compared to the current distribution. In RCP 8.5-2050, J. pyriformis and O. virginiana had a gain of more than 5 %. All species showed a reduction greater than 10 % under the RCP 8.5-2080 scenario. The models showed area under the curve greater than 0.8 and partial ROC (Receiver Operating Characteristic) greater than 1.7.

Conclusions

Understanding the response of 10 species to climate change will serve as a basis for proposing conservation and monitoring plans, since nine of them are in some category of risk.

Introduction:

Oregano (Lippia graveolens H. B. K.) grows in semi-arid ecosystems. There is no information on the population dynamics of this species at the Tehuacán-Cuicatlán Biosphere Reserve (RBTC).

Objective:

To determine the vertical structure and spatial distribution of L. graveolens in five topographic conditions in the RBTC.

Materials and methods:

Ten sampling units were established in five topographic conditions (TC), where six plant height categories were defined. Density and structural variables were measured, from which IVI was obtained and population structure curves were constructed. The spatial distribution pattern was analyzed with the Ripley\'s transformed function (L _(t) ).

Results and discussion:

TC1 showed population curve type IV (low frequency in the first, third and fourth height categories, high in the second and fifth categories, and low in the rest) with lower density (100 plants∙ha^-1; 1.6 %) in category 6 (>251 cm), and higher density (1 840 plants∙ha^-1; 29 %) in category 4 (151 a 200 cm). For TC2 to TC5, the curve was V-type (low frequency in the first category, gradual increase up to the intermediate category, and gradual decrease in the rest) with lower density (20 plants∙ha^-1; 0.4 %) in category 6, and higher density (2 320 plants∙ha^-1; 51 %) in category 4 which also had the highest IVI (92.8 to 126.1). Spatial distribution was aggregated in TC1 to TC4 and randomized in TC5.

Conclusions:

Topographic conditions influenced the vertical structure and spatial distribution of oregano.

Introduction

The Mexican spotted owl (Strix occidentalis lucida Nelson 1903) is a subspecies threatened by habitat destruction and sensitive to climate change. It is distributed in the old forests of the United States and Mexico.

Objective

To determine the potential historical (1970-2000) and future (2021-2040, 2041-2060 y 2061-2080) distribution of the Mexican spotted owl under two climate change scenarios (SSP 245 and SSP 585).

Materials and methods

Potential distribution was modeled using the R software with the MaxEnt algorithm, 155 geographically uncorrelated occurrence records, and five bioclimatic layers. Areas of environmental suitability were predicted for eight environmental management units in the United States and Mexico.

Results and discussion

Three temperature variables contributed 93.1 % to the model prediction: mean diurnal range (44.8 %), maximum temperature of the warmest month (28.8 %) and average of the coldest quarter (19.5 %). Future scenarios showed gradual and continuous losses of suitable bioclimatic space for the bird in seven management units, especially in the high emissions scenario (SSP 585) in the Sierra Madre Oriental de México (-56.1 to -96.4 %). The Southern Rocky Mountains environmental management unit in the United States was the only one that gained suitable bioclimatic space (51.3 to 167.2 %) in all periods.

Conclusion

Although changes are not significant, the loss of areas of bioclimatic suitability begins in 2030 and increases in 2041 and, therefore, climate change represents a current threat to this bird of prey.

Introduction

In the high mountain ranges of the Altiplano Potosino there are relict forests of Quercus spp. The species of ectomycorrhizal fungi associated with these ecosystems are so far unknown.

Objective

To know the morphology of Astraeus aff. hygrometricus (Pers.) Morgan associated with Quercus species in three sites of scarce precipitation in the Altiplano Potosino.

Materials and methods

Ectomycorrhizal fungi and vegetative structures of oak were collected during the rainy season for morphological characterization and identification. Soil physicochemical variables were evaluated by Tukey\'s analysis of variance and least significant difference (P = 0.05), to identify differences among the studied sites (Cerro El Peñon Blanco, Sierras de Guanamé and La Mojonera).

Results and discussion

The ectomycorrhizal species A. aff. hygrometricus was associated with Quercus potosina Trel., Q. pringlei Seemen ex Loes., Q. tinkhamii C. H. Muller and Q. striatula Trel. The fungi had five to 14 laciniae per basidiomata and the following diameter ranges: 13 to 20 mm (endoperidium), 42.3 to 57.4 mm (exoperidium), 8 to 10.1 µm (spore length), 4.4 to 6.9 µm (endoperidium hyphae) and 4.9 to 9.2 µm (exoperidium hyphae). Oak and fungal species were found in friable soils (sandy to clayey) with pH 5 to 7.7 and low nitrogen (<2 %) and high phosphorus contents (85 mg∙kg^-1).

Conclusion

The ectomycorrhizal association of A. aff. hygrometricus with oak species explains the survival of these shrub oak forests under the semi-arid environments of the studied sites.