DECOMPOSITION AND NUTRIENT RELEASE PATTERNS OF LEAVES OF Leucaena leucocephala (Lam.) de Wit, Guazuma ulmifolia Lam. AND Moringa oleifera Lam. IN A MIXED FODDER BANK
DESCOMPOSICIÓN Y LIBERACIÓN DE NITRÓGENO Y MATERIA ORGÁNICA EN HOJAS DE Leucaena leucocephala (Lam.) de Wit, Guazuma ulmifolia Lam. Y Moringa oleifera Lam. EN UN BANCO MIXTO DE FORRAJE
/ pages 5-25
Decomposition rates and nitrogen (N) and organic matter (OM) release patterns of leaves of Leucae¬na leucocephala (Lam.) de Wit, Guazuma ulmifolia Lam. and Moringa oleifera Lam. in a mixed fodder bank in Yucatán, Mexico, in the rainy and dry seasons, were assessed. The experimental units were formed in a randomized complete block design with five treatments and four replicates. A total of 120 litterbags were filled with fresh leaves of the species collected and placed in each experimental unit. We assessed three incubation periods per treatment: four, eight and 16 weeks for each season (rainy and dry). At the end of the experiment, it was apparent that the decomposition process was faster in the rainy season. Weight loss and N and OM release were faster in M. oleifera in monoculture and L. leucocephala and M. oleifera mixed. The decomposition patterns of all species followed the sim¬ple exponential model, with more than 80 % of the initial mass incorporated by the end of the study period. We concluded that G. ulmifolia, L. leucocephala, and M. oleifera in monoculture and mixtures demonstrated their ability to produce considerable amounts of OM and release significant amounts of N in short periods.
SEED TREATMENTS TO IMPROVE THE GERMINATION of Colubrina ferruginosa Brong
TRATAMIENTOS A SEMILLAS PARA MEJORAR LA GERMINACIÓN DE Colubrina ferruginosa Brong
/ pages 27-31
The achievement of the repopulation in projects for the rehabilitation of degraded ecosystems depends on the handling of seeds of forest species. Colubrina ferruginosa Brong seeds have a low germination capacity (40-60 %) making it difficult to obtain seedlings for planting. An experiment was conducted with the aim of improving the germination capacity of C. ferruginosa. The experiment was carried out during 60 days, using seeds harvested in February 2002, 400 per treatment. 10 treatments with 4 replications were evaluated using a completely randomized design, of which 9 treatments consisted of immersing seeds in water and the other treatment consisted of immersing seeds in boiling water for 30 s. Seeds were placed in germinating boxes with a growth medium made of 30 % sand and 70 % pine sawdust, and covered with the same sawdust; seeds were moistened daily with 733 mL of water. Germination values were transformed using the arc sine function √/x100 and were evaluated by means of a simple ANOVA. It was found that germination was significantly increased compared to the control treatment (50 %), with immersions of 3, 6 and 9 h (76-80 %).
FERTILIZATION WITH NITROGEN, PHOSPHORUS AND POTASSIUM IN Pinus patula Schl. et Cham SAMPLINGS.
FERTILIZACIÓN CON NITRÓGENO, FÓSFORO Y POTASIO EN UN LATIZAL DE Pinus patula Schl. et Cham.
/ pages 33-42
The forests today face the problem of productivity; it is demanded to increase in quantity and quality. Forest growth depends on several factors, including soil, which acts on the tree by the water and min¬eral elements. Forest productivity is increased by improving nutrient availability through fertilization. Consequently, this research is aimed to study the nitrogen fertilization (0, 138, 185), phosphorus (0, 15, 21), and potassium (0, 123, 164) kg•ha-1 compared to the growth of new foliage, using a 33 factorial experiment in a Pinus patula Schl. et Cham plantation of 10 year old trees, in Aquixtla, Puebla, dur¬ing 2009-2010. The instantaneous relative growth rate (TCRI, by its acronym in Spanish) in terms of new growth was better (0.0255 mL•mL-1•day-1) with a 185-0-0 kg•ha-1 NPK dose; and TCRI dry weight was better (0.0254 and 0.0249 g•g-1•day-1, respectively) with a 138-0-0 and 138-0-123 dose. Nitrogen deficiency was determined, which was attributed to soil acidity and the slow mineralization of organic matter. The recommended dose for soil and climatic conditions of the experimental site was 185-0-0 kg•ha-1 for volume of new foliage and 138-0-0 NPK kg•ha-1 for dry weight.
FINANCIAL FORECAST FOR AGROFORESTRY SYSTEMS IN El FORTÍN, MUNICIPALITY OF ATZALAN, VERACRUZ.
PROSPECTIVA FINANCIERA DE LOS SISTEMAS AGROFORESTALES DE EL FORTÍN, MUNICIPIO DE ATZALAN, VER.
/ pages 43-55
Agroforestry is an old land-use practice that has undergone significant change in the community of El Fortín, municipality of Atzalan, Veracruz. While the agroforestry systems once had a wide variety of components, they have been simplified into single-crop coffee, citrus fruit and banana systems, resul¬ting in an overuse of natural resources and increased poverty and migration. In light of this problem, this research analyzed the existing Agroforestry Systems (AFS) in the study area, using the Diagnosis and Design Methodology (D & D), in order to propose modifications and make new agroforestry design proposals. As a result, we proposed three new agroforestry systems, along with suggestions for better or new management practices. The species proposed are: gmelina (Gmelina arborea), allspice (Pi¬mienta dioica), soursop (Annona muricata), Mexican sarsaparilla (Smilax aristolochiaefolia), mountain immortelle (Erythrina poeppigiana) and signal grass (Brachiaria decumbens). These proposed chan¬ges are backed by ex-post and ex-ante financial assessments made for all systems studied for a 20- year period. We demonstrated through these assessments that these systems can provide additional income to reduce poverty and migration, plus conserve more natural resources in the study area. The ex-ante agroforestry systems (agrosilvicultural and silvopastoral) exceeded by more than 80 % the net income obtained by the ex-post systems.
CARBON STOCKS IN AGROFORESTRY SYSTEMS WITH COFFEE PLANTATIONS
ALMACÉN DE CARBONO EN SISTEMAS AGROFORESTALES CON CAFÉ
/ pages 57-70
This study was conducted with the aim of estimating carbon stocks in coffee-based agroforestry sys¬tems (AFS) in the Huatusco region, a major coffee (Coffea arabica L.) producing area in the state of Veracruz, Mexico, in order to obtain quantitative data on the carbon mitigation potential of major agro¬forestry systems in that region. To this end, carbon stocks were estimated for plant biomass and soil organic matter in the following agroforestry systems: coffee-banana, coffee-macadamia, coffee-pink cedar, coffee-sheep and coffee-Inga spuria, as well as a primary forest and a grazing land for com¬parative purposes. The samples were collected from 4 x 25 m (100 m2) plots for tree biomass, herbs and litter; for soil, the sampling depth was 0 to 30 cm. The highest amount of aboveground carbon, estimated using allometric models, was recorded for coffee-pink cedar (Co + Ce), with 114 Mg C•ha-1, followed in descending order by: coffee-macadamia (Co + Ma), with 34 C Mg•ha-1; coffee-Inga spuria (Co + In), with 29 C Mg•ha-1; coffee-banana (Co + Ba), with 27 Mg C•ha-1; and lastly the grazing land (G) with 2 Mg C•ha-1. For soil organic carbon, the Co + Ce treatment had the highest amount with 58 Mg C•ha-1, while the grazing land (G) had the lowest with 50 Mg C•ha-1. As far as total organic carbon is concerned, the maximum amount of 172 Mg C•ha-1 was found in Co + Ce and the minimum, 65 Mg C•ha-1, in the grazing land. In conclusion, among the coffee-based systems studied, the average carbon stock is 102 Mg C•ha-1, compared to 52 Mg C•ha-1 for the grazing land and 355 Mg C•ha-1 for the primary forest, which stores the most total carbon.
DIVERSITY OF USEFUL SPECIES AND AGROFORESTRY SYSTEMS.
LA DIVERSIDAD DE ESPECIES ÚTILES Y SISTEMAS AGROFORESTALES.
/ pages 71-86
Biodiversity management and use sustain multifunctional agro-ecosystem services, such as: food sup¬ply, fodder, firewood, timber, fuel, fiber, and aquifer recharge, among others. The loss of biodiversity and increased risks of its deterioration, frequently inherent to several human activities, raise the need to develop institutional and social capacities for their restoration and conservation. The objective of this work was to identify and describe the diversity of trees and bushes, their uses and types of agro¬forestry systems. It is important to know the multiplicity of uses, as a synthetic expression of functional logic that makes agroforestry land systems viable. The study’s descriptive methodology was based on participatory workshops designed to know the diversity of resources and uses. The subsequent steps involved: selection of families, transects, interviews, records, and collecting and classifying specimens. In total, 81 species and 34 families were identified. Diversity is amplified by the multifunc-tionality of uses for 55.6 % of the species: 7.4 % with 5 types of uses; 11.1 %, with 4 types; 14.8 % with 3 types; and 22.2 %, 2 types. Types of uses: firewood, 41 species; medicinal 30 species, tool-making 29, timber, 25; feed purpose, 23; forage species, 20, and 6, hedgerows. Some 91.7 % of households use agrosilvicultural systems and 41.7 % silvopastoral ones, according to various socio-economic purposes and use combinations.
ENVIRONMENTAL IMPACT ASSESSMENT AND SUSTAINABLE DEVELOPMENT IN SAN PEDRO MIXTEPEC, JUQUILA, OAXACA.
LA EVALUACIÓN DEL IMPACTO AMBIENTAL Y EL DESARROLLO SUSTENTABLE. ESTUDIO DE CASO SAN PEDRO MIXTEPEC, JUQUILA, OAXACA.
/ pages 87-99
The problematic concerning environmental impact in Mexico means that no assessments on effectiveness as an instrument of environmental policy have been conducted; therefore it is important to know whether the instrument meets or contributes to the basic principles of sustainable development, con¬sidering that it must evolve and be in a process of continuous improvement. Precautionary approach should be assured to provide certainty on environmental feasibility of different projects, which aim to promote development. In this study, a hypothetical-deductive research along with a correlational and descriptive empirical method were used, elaborating collection, analysis and evaluation of existing information, mainly on environmental impact statements of development projects with expert opinion, in San Pedro Mixtepec, Juquila, Oaxaca. Results show that the information presented is superficial, without providing scientific knowledge on true impacts generated by the project and/or activity to the environment and natural resources. It can be concluded that these documents play an important role, because they allow the identification of negative environmental impacts, and at the same time, harmonize these effects by applying prevention or mitigation measures that promote a balance between environmental conservation and development.
HISTORICAL ANALYSIS OF THE BIOLOGY OF CHEREHUITA (Hubbsina turneri) (PISCES:GOODEIDAE), ENDEMIC AND THREATENED SPECIES FROM MEXICO.
ANÁLISIS HISTÓRICO DE LA BIOLOGÍA DE LA CHEREHUITA (Hubbsina turneri) (PISCES:GOODEIDAE), ESPECIE ENDÉMICA Y EN PELIGRO DE EXTINCIÓN DE MÉXICO.
/ pages 101-110
The present study integrates a historical description of different biological aspects of Hubbsina turneri in the Cuitzeo Lake and the Zacapu Lake in Michoacán. The historical analysis responds to the restricted and threatened situation of the species and provides important information to promote conservation. Length-weight relationship indicates an isometric growth mainly related to the individuals from the Zacapu Lake. The condition coefficient of fish was greater in Zacapu (3.41) than in Cuitzeo (3.29), aspect that could be related to better development conditions in Zacapu (food and habitat). 25.9 mm standard length was determined as the average size for the first reproduction in females. This species had multiple reproductive cycles and fry born continuously from April to November. Sexual proportion presented dominance from females on males. The stomach content analysis revealed that H. turneri is an epibentophagic to bentophagic carnivorous. Diet presented no significant difference when comparing populations from both lakes (MRPP analysis, A = -0.02, p = 0.71). The trophic level classified the species as primary consumer, related to the high detritus consumption. Finally, restoration measures must be implemented in Cuitzeo Lake, principally the wastewater diversion and treatment. In Zacapu Lake, conservation measures must be related to the restriction of spring water extraction to maintain the hydrodynamic ecosystem processes.
SOCIO-ENVIRONMENTAL RELATIONSHIPS BETWEEN COMMUNITIES AND PROTECTED NATURAL AREAS. CALAKMUL BIOSPHERE RESERVE: BETWEEN CONFLICT AND CONSERVATION.
RELACIONES SOCIOAMBIENTALES ENTRE COMUNIDADES Y ÁREAS NATURALES PROTEGIDAS. RESERVA DE LA BIOSFERA CALAKMUL: ENTRE EL CONFLICTO Y LA CONSERVACIÓN.
/ pages 111-121
In the Calakmul Biosphere Reserve (CBR), a conflictive relationship has developed between communities and reserve management because their relationship is governed by a principle by which the logic of environmental management subordinates the logic of those who have profited from the region’s resources and is manifested in restrictions on land use and productive activities. Thus, the objective of this research was to determine the root causes of the conflict. For the analysis of the conflictive relationships, qualitative indicators that emerged directly from the information obtained through the use of structured questionnaires, indepth interviews and direct observation were used. To check the validity of the qualitative analysis, two statistical methods were used: correlation coefficient and principal components. It was found that the conflict is due to the producers or rural communities not participating in the planning processes and in the making, implementation and evaluation of decisions related to actions carried out in the CBR by reserve management.
OPTIMIZATION OF A PROTOCOL FOR DNA ISOLATION AND ISSR-PCR AMPLIFICATION SYSTEM FOR Ceratozamia mexicana Brongn. (Zamiaceae).
OPTIMIZACIÓN DE UN PROTOCOLO DEL AISLAMIENTO DEL ADN Y DE UN SISTEMA DE AMPLIFICACIÓN ISSR-PCR PARA Ceratozamia mexicana Brongn. (Zamiaceae).
/ pages 123-133
Most of the cycads contain high concentrations of essential oils, flavonoids, polyphenols, and polysaccharides that interfere with DNA extraction, causing erroneous or no PCR products. The optimization of DNA isolation, employing inter-simple sequence repeats (ISSRs) primers were investigated in Ceratozamia mexicana Brongn., an endangered Mexican cycad. The DNA obtained from fresh-leaf tissues with a modified cetyltrimethylammonium bromide buffer protocol gave a good quality of DNA with no colored pigments and contaminants. The main modification to the CTAB-based DNA extraction protocol was the one hour leaf tissue soaking pre-treatment with a 0.7 M NaCl solution, to facilitate the cell lysis. The DNA extracted was successfully amplified by PCR using six arbitrary ISSR primers. Reproducible amplifiable products were observed in all PCR reactions. Our results show a significant improvement in the DNA quality obtained using low primer concentration (25 pM). 23 strong bands were detected, 9 of which were polymorphic. The results indicated that the optimized protocol for DNA isolation and PCR system is suitable for further work in this specie. This work is the first DNA extraction and ISSR protocols reported for this ornamental and endangered species.
NEUROPROTECTIVE AND NEUROREGENERATIVE ACTION OF SALTS OF ISOLATED RESIN ACIDS OF CONIFERS ROSIN FROM WESTERN CUBA
ACCIÓN NEUROPROTECTORA Y NEURORREGENERADORA DE LAS SALES DE ÁCIDOS RESÍNICOS AISLADOS DE COLOFONIA DE CONÍFERAS DEL OCCIDENTE DE CUBA
/ pages 135-142
Neuropsychiatric diseases affect more than 10 % of the Cuban population and 25 % worldwide. Most drugs used to treat central nervous system disorders are expensive and create severe side reactions. Efforts are currently being developed for the implementation of secondary metabolites such as environmentally sustainable sources for the treatment of nervous system diseases, including stroke and other Parkinson’s-type neuropathologies, and Huntington’s motor disorders, enabling an effective neuroprotection as well as short periods of neuroregeneration time with minimal sequels. The objective was to evaluate the neuroprotective and neuroregenerative action of sodium salts of isolated resin acids from Cuban conifers. The study results suggest that the sodium salt of resin acids can be used as a structural bioisosteric isoanalogue precursor with specific therapeutic actions such as neuroregeneration and neuroprotection in the treatment of ischemic diseases.