The research reported here was carried out in coffee plantations belonging to a union coffee troducers “Majomut”, from the Tzotzil native communities of Taquihucum and Polhó, in the municipality of Chenalhó, in the State of Chiapas, México. The objective was to evaluate the sustentability, as a function of the nutrient balance, inputs an outputs in particular of coffee plantations as agroecosystems under organic management compared with those under traditional management. Most salient results indicate that those agroecosystems studied under organic management, are sustainable from the viewpoint of nutrient balance, and their productivity is more sustainable in time than that of agroecosystems under traditional management. In both kinds of agroecosystems Potasium was identified as a limitant for sustentability, and the vegetational component “Chalum” (a legume of the genus Inga) used for shade in coffee plantations, was identified as contributor of nutrients, mainly nitrogen, contained in fallen leaves.

Death, along with growth and differentiation, is a critical part of the life cycle of a cell. Homeostatic control of cell number is thought to be the result of the dynamic balance between cell proliferation and cell death. Researchers have become increasingly more aware during this time that this type of “natural” death, which is now called apoptosis or programmed cell death, is a widespread phenomenon that plays a crucial role in a myriad of physiological and pathological processes. Selective death of cells, tissues, and organs is an essential feature of plant development and survival. Programmed cell death is essential for normal reproductive and vegetative development and for responses to environmental stress.

Though Mexico has an old tradition in the official regulation with respect to the protection and conservation of its natural resources, this to a large extent only has existed like dead letter inside the legislation, therefore in the reality each time is more evident the deterioration of those resources. In spite of this, the National Park Iztaccíhuatl-Popocatépetl-Zoquiapan and Anexas, even lodges a high percentage of the endemic biodiversity to Transmexican Volcanic Axis and, to include the highest mountains of Mexico, with its noticeable gradient altitudinal, constitutes a combination that causes the great diversity and development of vegetation strata different and various fauna. Historically, the present state of the natural resources in the area of influence of the Park, has been product of two forms of extraction and advantage; on the one hand, the set of agricultural and stock breeding activities of the communities established in the area of influence of the park, that is characterized for being of extensive type, with a fundamentally traditional technology, that it practices to a large extent under conditions of seasonal rains; the second dimension of the relation between the man and their environment, has been the commercial, intensive and predator activity of the forest resources, that carried out without the most minimum legal control, has generated areas increasingly more extensive in which the effects of the deforestation and alteration of the habitat are observed; they are a clear index of the imbalance at that the relation man-nature has arrived.

In this work is proposed a definition of ecological design of forest plantations, and are mentioned some twenty items on such issue. Also is referred the relationship among ecological design and aesthetic design of forest plantations. In this work are included genetics, seedling quality, choice of species and provenances, mixture of species and ages, microsites, nurse species, gaps, and landscape patterns, among others, including some social considerations. All of them focused to obtain a reliable forest restoration.

A study about the edible forest mushroom production was conducted at Santa Catarina del Monte, Mexico. The experimental period took place in five plots of land of one hectarea situated in stands of Pinus hartwegii Lindl., and Abies religiosa (Schl. et Cham.) H.B.K. The phenology of fungi species appearance was determined as well as unity surface production, economical value per hectarea, and the ecological conditions of forest stands. The average of monthly fungi production. To each vegetation type was analyzed according to the variation of temperature, precipitation and relieves moisture during the year. Correlation method determined the association degree between fungi production and the variables indicated below: fungi species, tree average age, tree average diameter, and average of monthly temperature and monthly precipitation. Following the procedure of multiple regression and the Stepwise method variables with he most influence over the fungi production were fungi species, average of monthly temperature, average of tree diameter, monthly precipitation and average of tree age. A total of 24 species was in the forest, of which three were exclusive of Pinus hartwegii forest and the nine of Abies religiosa forest, and 12 common species to both types of forests. Fifteen different species were found at Pinus hartwegii forest with an average production of -107.3 kg·ha·-1 with an economical value of $5,962.00·ha·year-1. At Abies religiosa forest twenty-one different species found with a total production of 214.10 kg·ha-1·year-1, and an economical value of $9,744.50·ha·year-1 prices of 1987.

Cone and seed production and cone distribution in the canopy and cone and seed characteristics were analyzed in a plantation of Mexican pinyon pine. A random sample of trees was taken in the number of cone produced was registered along with their distribution in the canopy. The cones were harvested, measured and their seeds were counted; their seeds were weighted and measured. The results indicated that there were statistical differences between years among the trees which produced cones. In the first year, only 5.07 percent of the trees produced cones, in the second 27.6 % and whereas by the third 30.18 percent did produce cones. The cone production by tree was significant among year, in the first was of 3.12, in the second of 8.75 and 17.44 by the third. The cone distribution in the canopy was also different; the distal third contributes whit 42.76 percent, followed by the middle third with 38.85 percent whereas the basal third 18.37 percent. The morphological features of the cones were similar in the two years of evaluation in relation to the weight, diameter and number of seed per cone; there was only significant differences (P

This work was conducted in the Sierra de la Candela mountain range on the High Basin of Nazas river in the state of Durango. The goal was to develop a classification of the different types of vegetation associations, as a basic tool for comparing the evolution of vegetation in the region, utilizing Lansat ETM and MSS satellite images and local cartography. A vegetation map current was first obtained from the images, containing 13 classes of vegetation associations. Afterwards they were reclassified into five classes. The multi spectral analysis gave as a result an increase in grassland areas and open forests in decline of closed and semi closed forest.

Decline of Abies religiosa at the Desierto de los Leones Park, D. F. is a process with many poorly studied aspects to date, which makes it difficult to clearly understand the causes of the phenomenon. In this work, the nutrient status of the species and its relationship with the degree at which two of the main symptoms, chlorosis and reddening appear, were studied. Samples of A. religiosa foliage of approximately 1.5 years old, with symptoms at five different levels, 0, 25, 50, 75 and 100 were selected. Each level of the symptoms was replicated five times and the data were processed by using analysis of variance. The results show an inverse relationship between the degree of chlorosis and N, P and K concentrations in addition to Mg and Mn deficiencies. Foliage reddening seems to be related to N deficiencies, accompanied with generalized K, Mg and Mn deficiencies.

Individual growth assessments on length, weight, mortality and survival rate were carried out in Chirostoma humboldtianum from San Miguel Arco reservoir on April 2005. The reservoir is located at 99° 32’ 10” west longitude, and 20° 24’ 42" north latitude. Five sample stations were set up, in each station, silverside fish were caught in a mesh of measure ring 30 x 2 meters with 8.0 millimeters aperture. The constants of the growth model, condition factor related to weight-length, growth type (and its t-student test), mortality and surviving rate, were estimated. The maximum length was estimated bye Ford Walford method. The maximum length was 8.9760 cm, the growth rate -0.5230, maximum weight 10.3689 g, condition factor 1.13 %, the growth type was isometric 3.10 (t

The urban lakes are interesting systems because recreative, cultural and stetics places, by another way, they are important to several kinds of organism like Poecilia reticulata; it has a high tolerance to several environmental changes and its reproducing is more easy. The main goals of this work were: to determinate changes about abundance and biomass of Poecilia reticulata into Tezozomoc’s Park lake; and to achieve the growth equation. Each month were taken samplings, to July of 2000 to June of 2001, in three work stations into the lake. Depth, transparency, alkalinity, hardness, pH, conductivity, temperature and turbied were obtained by conventional methods. The biological samplings, the fishes, were captured using a spoon net of rectangular shape 100x50 cm (area 0.5 m²). The fishes were introduced into formalin to 10 % and, after that, carried to laboratory. Then, they were to weigh on digital scale and measured with a Vernier to standard length (mm). All this several parameters were used to know about abundance and weight to each work station and, growth equation like Von Bertalanffy model were obtained to all. The water is warm, muddy, alkaline and hard, apart from shallow. The highest abundance (6148 organisms) and biomass (677.28 g) had have work station 1 because people throw food waste. July (1,483 org.) and August (1,252 org) had highest abundance however, August (145.12 g) and March (138.63 g) had highest biomass. The condition factor highest were in March (0.03) because gravid female and adult male. Finally, about growth model, maximum length was 61.55 in the same way growth rate was 0.2987 as well as natural systems.