TRAPPING OF Phytophthora cinnamomi IN OAK FORESTS WITH TWO ORNAMENTAL SPECIES AND INDUCTION OF SPORULATION.
TRAMPEO DE Phytophthora cinnamomi EN BOSQUE DE ENCINO CON DOS ESPECIES ORNAMENTALES E INDUCCIÓN DE SU ESPORULACIÓN.
/ pages 5-12
Oak mortality has increased in recent years in several Mexican states. The etiology in many cases is unknown. In the states of Colima, Jalisco and Guerrero, where the cause is known, the oak forests are being affected by the “ink disease” (Phytophthora cinnamomi Rand). The presenting symptoms of diseased trees are: chlorosis, necrosis, wilting, cankers with dark exudates on the bark of the trunk and dieback. Given the impact of the disease and the difficulty of isolating the pathogen from cortical tissue and inducing sporulation in it, this study aimed to (i) evaluate the efficiency of two trap plants, Camellia japonica and Rhododendron indicum (L). Sweet, using a soil suspension and (ii) induce sporulation of the pathogen. To this end, 6 mm discs containing leaf tissue of the trap species were embedded in a soil suspension for 24 and 48 h before being plated in PARPH selective medium. The species R. indicum showed higher capture effectiveness, 64.10 %, compared with 6.83 % for C. japonica. For sporulation, a water-soil mixture (350 mL-200 g) gave the best results.
DESIGN OF A COMPUTER SYSTEM TO DETERMINE ECOTOURISM SUITABILITY OF FOREST AREAS
DISEÑO DE UN SISTEMA DE CÓMPUTO PARA DETERMINAR APTITUD ECOTURÍSTICA DE ÁREAS FORESTALES
/ pages 13 - 28
The aim of this study was to design and develop a computer system (software) capable of generating ecotourism suitability maps. Therefore, a conceptual model was structured combining GIS and multicriteria evaluation tools in a decision- making environment. The software design was performed according to the conceptual model and, lastly, the design was coded in the programming language Visual Basic®. As input values, the system uses criteria and indicators (mappable) for the proper development of any ecotourism interest and corresponding thematic maps. The output information is the raster map whose cells have gradient values ranging from 0 to 1, which represents the cell’s ability to develop the evaluated ecotourism activity. This system can be a valuable, effective and efficient tool in the decision-making process and land use planning.
CLOUD FOREST AND CLIMATE CHANGE SCENARIOS: AN ASSESSMENT IN HIDALGO, MÉXICO
BOSQUE MESÓFILO DE MONTAÑA Y ESCENARIOS DE CAMBIO CLIMÁTICO: UNA EVALUACIÓN EN HIDALGO, MÉXICO
/ pages 29 - 43
The habitat of eight forest species (Liquidambar macrophylla, Alnus arguta, Carpinus caroliniana, Clethra mexicana, Pinus patula, Nectandra sanguínea, Podocarpus reichei and Quercus spp.) representative of cloud forest in the state of Hidalgo was assessed under current and projected climate conditions. We used the ecological niche conceptual framework and considered twelve variables: one related to topography, five to landscape and six to climate. An ecological niche factorial analysis was carried out with Biomapper software. Habitat suitability maps were obtained for each forest species by changing six climatic variables for each climate change model applied, generating the same number of maps for future conditions. We analyzed the differences in suitable habitat for current conditions and those projected by climate change, finding that the optimal growth area for six species may be reduced. The species identified as threatened by climate change are L. macrophylla, A. arguta, C. caroliniana, C. mexicana, P. patula, and N. sanguinea, which comprise mainly the high tree layer of the cloud forest. We therefore conclude that the ecosystem can be seriously affected by climate change.
THE PROCESSES OF DESERTIFICATION AND ARID REGIONS
LOS PROCESOS DE DESERTIFICACIÓN Y LAS REGIONES ÁRIDAS
/ pages 45 - 66
This paper presents a review of desertification, a process of degradation of the productive capacity of the land, particularly in arid and semiarid regions of the world. Because desertification increases gradually, the reasons why this worldwide phenomenon occurs and worsens were studied. In general, desertification results from the combined pressure of an adverse and fluctuating climate and overexploitation of natural resources. Aspects related to the extent and severity ofdesertification worldwide are explored, as well as the particularities of land degradation in Mexico. Moreover, the characteristics of desertification processes are outlined, taking into account the intricate network of relationships between environmental conditions and productive activities and their effects on biotic, edaphic and hydrological resources. Finally, a series of proposals relating to the application of preventative and corrective measures that tend to prevent and curb desertification are presented.
AGROFORESTRY CHARACTERIZATION IN TRADITIONAL AND RUSTIC COFFEE SYSTEMS IN SAN MIGUEL, VERACRUZ, MEXICO
CARACTERIZACIÓN AGROFORESTAL EN SISTEMAS DE CAFÉ TRADICIONAL Y RÚSTICO, EN SAN MIGUEL, VERACRUZ, MÉXICO
/ pages 67 - 80
Agroforestry characterizations were conducted in rustic and traditional coffee plantations in San Miguel, Amatlan de los Reyes, Veracruz, Mexico. The aim of the present study was to analyze and compare these systems. Results indicate that both systems gained similar economic benefits, although the species composition of the canopy and products obtained are different. Timber (Cedrela odorata, Robinsonella mirandae and Mastichodendron capirii), coffee (Coffea arabica and C. canephora) and palms (Chamaedorae tepejilote and Chamaedorae elegans) are the main economic products. The benefit/cost ratio acquired by selling agricultural and forest products shows a greater economic profit for rustic coffee system ($ 20,784.00·year-1·ha-1) compared to traditional coffee system ($ 19,236.00·year-1·ha-1). Although both systems have relatively good gains, the effect that the rustic coffee system has on forest resources may be shortly sustainable over time, because reforestation does not occur in this case. Traditional coffee system is in a better condition of sustainability and long-term production, because the elements used in the marketing of timber and fuel are reforested due to their commercial importance.
SOFTWARE TO IDENTIFY CLIMATE CHANGE TRENDS AT THE LOCAL LEVEL: A STUDY CASE IN YUCATÁN, MÉXICO
SOFTWARE PARA IDENTIFICAR LAS TENDENCIAS DE CAMBIO CLIMÁTICO A NIVEL LOCAL: UN ESTUDIO DE CASO EN YUCATÁN, MÉXICO
/ pages 81 - 90
The present work shows the architecture and capabilities of the software titled “Data Analysis System for monitoring regional and local climate change with agroclimatic indexes” (Moclic). The software works as: a) a database; b) a processing tool of agroclimatic data; and c) a tool for identifying local climate change trends. The advantages of using Moclic include its capacity for evaluating climate change within a graphical user interface. The software requires input data from weather stations containing the following information: station name, key number, locality and state, monthly average, minimum and maximum temperatures, monthly precipitation and the geographic coordinates of the station. Moclic can process the input data and calculate derived variables related to potential evapotranspiration and monthly and annual indexes for humidity, aridity, the growing season, precipitation concentration, erodibility, and soil leaching. Moclic software works in both English and Spanish. Finally, a case study of the Abalá station in the state of Yucatán, México is presented in order to show the applicability of Moclic at the local level. The results from the case study show the high accuracy of the Moclic for the prediction of climate change trends throughout the last 40 years, and suggest its high potential to be used in new climate scenarios.
TREE STRUCTURE AND COMPOSITION OF A FRAGMENT OF CLOUD FOREST IN VERACRUZ STATE
ESTRUCTURA Y COMPOSICIÓN ARBÓREA DE UN FRAGMENTO DE BOSQUE MESÓFILO DE MONTAÑA EN EL ESTADO DE VERACRUZ
/ pages 91 - 101
The tree structure and composition in a fragment of cloud forest in the central region of Veracruz state were analyzed using three 2,000 m2 transects, in which dasometric data were taken from all individuals with DBH > greater than 10 cm. We found 239 individuals belonging to 14 species, 12 genera and 12 families. The family Fagaceae was dominant in the sampling areas. Quercus salicifolia, Liquidambar styraciflua, Quercus leiophylla and Alchornea latifolia were the most important species. They showed significant allometric relationships between the variables coverage-DBH, and height-DBH (except A. latifolia). We propose a possible synecological variant of cloud forest through the association Q. salicifolia-L. styraciflua, which reflects the low species richness reported.
Leucaena lanceolata S. Watson ssp. lanceolata, FOREST SPECIES WITH POTENTIAL TO BE SUBMITTED IN SYLVOPASTORAL SYSTEMS
Leucaena lanceolata S. Watson ssp. lanceolata, ESPECIE FORESTAL CON POTENCIAL PARA SER INTRODUCIDA EN SISTEMAS SILVOPASTORILES
/ pages 103 - 114
The usefulness of forest species in agricultural production systems is an option that helps to reduce the pressure in natural forests; they can also be used in treeless areas. The aim of this study was to evaluate the nutritional quality, germination, development of seedlings grown in nursery and variety of uses of Leucaena lanceolata S. Watson ssp. lanceolata. Edible material and seeds were collected in Tomatlán, Jalisco. Bromatologic analyses, scarification tests and the evaluation of seedlings grown in nursery using three soils with different pH values were performed. The experimental design was completely randomized, with Tukey (P≤0.05) test for media comparison. A survey study, bibliographical revision and review of specimens in the herbariums were used to know the local and potential diversity of uses of this specie. Results show high content of dry matter (97.40 %) and crude protein (29.05 %), greater germination using heat treatments, better seedling development in slightly acid soil (6.57) and the diversity of uses including firewood, forage and timber among others. L. lanceolata represents a viable option to be used in dry tropical silvopastoral systems due to the high nutritional value and the diversity of uses in rural areas.
TANNIN CONTENT IN THE BARK OF TWO SPECIES OF PARACATA (Erythroxylon compactum Rose and Senna skinneri Benth. Irwin & Barneby)
CONTENIDO DE TANINOS EN LA CORTEZA DE DOS ESPECIES DE PARÁCATA (Erythroxylon compactum Rose y Senna skinneri Benth. Irwin & Barneby)
/ pages 115 - 124
Tannins were obtained from Parácata (Erythroxylon compactum Rose and Senna skinneri Benth. Irwin & Barneby) bark by aqueous extraction using a 2k experimental design, with k = 4 and n = 2. The factors and levels were: Factor A = particle size (0.417, 6.68 mm), Factor B = extraction time (120, 180 min), Factor C = extraction temperature (80, 87 °C), Factor D = solid-liquid ratio (1:15, 1:12). The tanning quality of the tannins was evaluated. A deerskin was tanned using S. skinneri tannins and its tear load and tensile strength were determined. Test results for the physical and mechanical properties of the tanned leather were higher than the minimum values recommended by Mexican standards. We therefore conclude that the tannins in S. skinneri bark are suitable for use in tanning.
CARBON BASELINE IN A MIXED PINE-OAK FOREST IN THE JUAREZ MOUNTAIN RANGE (OAXACA, MEXICO) USING THE CO2FIX V.3.2 MODEL
LÍNEA BASE DE CARBONO EN BOSQUE MIXTO DE PINO-ENCINO DE LA SIERRA JUÁREZ (OAXACA, MÉXICO). APLICACIÓN DEL MODELO CO2FIX V.3.2
/ pages 125 - 137
Forest stands play a key role in carbon (C) sequestration. Numerous methods and models have been developed to estimate the carbon reservoirs and flows present in these ecosystems. In this study, the CO2FIX v.3.2 simulation model was used to analyse the C baseline in a pine-oak forest in the Juarez Mountain Range (“Sierra Juarez”), Oaxaca, Mexico. The first aim was to compare the results of this model with results obtained by direct sampling and allometric equations. Moreover, a second objective was to identify the elements which constitute the C baseline for a possible assessment of further forestry management which includes the environmental service of C sequestration. Once the data were obtained and results compared with previous studies, it was found that the CO2FIX v3.2 model is capable of determining the C reservoirs and flows in these ecosystems simply and efficiently, thereby enabling estimation of the C baseline. This provides communities with limited economic resources access to a tool which is capable of assessing the ability to sequestrate C and receive support as part of the environmental service of C sequestration.
MEASURING AND ESTIMATING THE BELOW-CANOPY LIGHT ENVIRONMENT IN A FOREST. A REVIEW
MEDICIÓN Y ESTIMACIÓN DEL AMBIENTE LUMÍNICO EN EL INTERIOR DEL BOSQUE. UNA REVISIÓN
/ pages 139 - 146
The below-canopy light environment influences the survival, the tree regeneration growth and the development of the understory plant species. Therefore, there has been much interest in measuring the below-canopy light environment. Several instruments, techniques and methods have been developed to measure directly or to estimate indirectly the below-canopy light environment. To date, many comparisons of direct and indirect methods for the measuring and estimation of below-canopy light environment have been conducted in order to determine the best way to measure the light in the understory. In this review a scientific description of the currently instruments, techniques and methods used to measure or to estimate the below-canopy solar radiation is shown. The nature and properties of the different methods, techniques and instruments are commented. Finally, the choice of equipment to meet the needs of the researcher in this topic is supported.
LITTERFALL PRODUCTION IN A Pinus cembroides ZUCC. STAND, IN ARTEAGA COAHUILA MEXICO AND ITS RELATIONSHIPS TO CLIMATIC VARIABLES
PRODUCCIÓN DE HOJARASCA EN UN RODAL DE Pinus cembroides Zucc. EN ARTEAGA, COAHUILA, MÉXICO Y SU RELACIÓN CON LAS VARIABLES CLIMÁTICAS
/ pages 147 - 155
Litterfall represents the main source of organic matter in terrestrial ecosystems. The assessment of litterfall production is important to understand the forest productivity, but it also provides important information as phenological indicator of the climate change effects. This study was carried out in a young Pinus cembroides Zucc. stand in La Sierra de Arteaga, Coahuila, Mexico. Litterfall was collected monthly using 40 traps (1 m2) located systematically on 1-ha plot. The Kruskal-Wallis non parametric test was employed to detect significant differences among sampling dates. The stepwise regression and the principal component analysis were employed to evaluate the relationships of litterfall to climatic variables. Total annual litterfall was over 1000 kg.ha-1.year-1, which was dependent on temperature and wind. Needles and branches comprised about 33 and 22 % of the total litterfall.
SOIL ORGANIC CARBON CONTENT UNDER DIFFERENT FOREST CONDITIONS: MONARCH BUTTERFLY BIOSPHERE RESERVE, MEXICO
CONTENIDO DE CARBONO ORGÁNICO EN EL SUELO BAJO DIFERENTES CONDICIONES FORESTALES: RESERVA DE LA BIOSFERA MARIPOSA MONARCA, MÉXICO
/ pages 157 - 173
Globally, the soil stores twice as much carbon as the atmosphere and nearly twice the amount stored in vegetation. Carbon storing capacity of the soil depends on its properties and land use. The aim of this study was to analyze the soil organic carbon content under different forest conditions within mountainous forests of the Monarch Butterfly Reserve in Mexico. We defined six sampling groups based on three forest conditions (conserved, harvested and disturbed) and two vegetation types (sacred fir and pine-oak). We calculated the carbon stock of four complete soil profiles in each group (N=24), starting with the A horizon. Results show differences in SOC content in soils under different forest types and forest conditions. Conserved sacred fir stands have an average SOC of 153 MgC·ha-1, while harvested and disturbed stands have 95 and 125 MgC·ha-1, respectively. In the pine-oak forests, average SOC content of conserved stands is 103 MgC·ha-1, while harvested and disturbed stands are 39 and 13 MgC·ha-1, respectively. Conserved forests hold 40-80 % of SOC within the A horizons. Therefore, SOC content should be taken into consideration when assessing the impact of forest management or any other forest conservation policy.
INFLUENCE FACTORS IN ROOTING OF CUTTINGS OF Abies religiosa (Kunth) Schltdl. et Cham
FACTORES DE INFLUENCIA EN EL ENRAIZAMIENTO DE ESTACAS DE Abies religiosa (Kunth) Schltdl. et Cham
/ pages 175 - 184
Forest decline in Desierto de los Leones National Park in Mexico City affects Abies religiosa, a dominant and hard-to-root species in the region. As a result of this decline, the species requires propagation in the region through rooting of cuttings. In this study, a method of vegetative production was developed to determine whether the effect of origin, age of the material, type of hormone used and the presence of decline symptoms affect the rooting capacity of cuttings of this species. Three experiments were conducted, and only the third one produced rooting of cuttings. In this experiment, a substrate composed of peat moss and perlite was used to test rooting of cuttings of two origins, with and without symptoms, generated in two growing seasons and using two auxins (indol-butyric acid and naphthalene acetic acid), keeping the soil moisture between 75-80 %. The combination of these factors produced 16 treatments, which were replicated 50 times. Data were processed by factorial analysis of variance. Results indicate that early December is the best time to collect plant material for rooting of A. religiosa cuttings, as they are the youngest, and that those that received indol-butyric acid rooted the best. Origin and decline symptoms had no effect on rooting.