Physiological ecology of tropical trees has moved forward remarkably in the last years, especially in the water relations issue. This progress has been accompanied by a notably development of techniques and instrumentation to study and measure the physiology of trees, such as the use of stable isotopes and sap flow probes. This article includes aspects of water uptake and transport, its environmental regulation and the functional convergence in hydraulic architecture, water relations, photosynthesis, respiration and growth. Additionally, aspects related with the physiological research involved in studies on global change are discussed.

The ecological studies of the Corixidae family (Hemiptera) in Mexico are scarce and fragmentary.The objectives were to analyze the spatial variation and temporal of this family in an urban lake and to relate these aspects with some environmental parameters during an annual cycle. Were made a monthly samplings during July from the 2000 to June 2001, locating three littoral stations and determining in each one of them: depth, transparency, temperature, oxygen, pH, conductivity, hardness and alkalinity. The corixids were captured with a rectangular sweepnet. An analysis of simple correlation was made between the total abundance of the corixids and the physical and chemical parameters The results showed the presence of three species whose abundances were: Graptocorixa abdominalis (Say, 1832) with 53%, Corisella edulis (Champion, 1901) with 43% and Krizousacorixa femorata (Guérin, 1857) with 1%. Were captured 2423 organisms which the highest abundance registered in March coinciding with the highest values in depth and of oxygen. The lowest abundance was presented in June and it coincided with the lowest values in alkalinity. The correlation between the parameters and the abundance was positive and significant with the depth, the oxygen and the conductivity. The station I presented the highest corixids abundance and the station III the lowest abundance. The variations registered in the abundance of these organisms are in function of the contribution of water that receives the lake, as well as for the location of the sampling stations.

Was studied the germination of Nolina parviflora (H.B.K.) Hemsl. Its range includes semiarid localites, forming part of the rosetofilous shrubland, mostly in the Hidalgo, Puebla, Oaxaca and Veracruz states. Were taken in account the following factors and levels: temperature (20, 25 and 30 °C), light (permanent and darkness), seed size (small -3.2 mm length and big -3.6 mm), and soaking as pregerminative treatment (during 24 h and without soaking). The seed has an ovoid shape, 3.4 mm length and 2.65 mm width. There were 59131 seeds per kilogram, 83.9% purity, and 9.8% humidity content, dry weight basis. The viability (flotation in water and tetrazolium tests) was equal to 100%. The following interactions were significant for germination: temperature and light (p = 0.0001), seed size and light (p = 0.069), and seed size and temperature (p = 0.0173). Germination was high without light at 20 (87.5%) and 25 °C (88.1%), declining at 30 °C (15.8%). Under permanent light, the higher the temperature, the lower the germination. For the germinative energy (number of days for reaching 75% of final germination), the interaction light and temperature was significant (p = 0.0001). At 20°C without light, it had a value of 15.5 days, and 19.7 days with light. At 25 °C, these values were 15.3 and 26 days, respectively, while at 30 °C, such values were 22.5 and 1.6 days, respectively. This results suggest that shaded microsites are appropriate for the germination of the seed of this species.

Pine sawdust of pine is a waste industry product. It is cheap and has been used as substrate with good results. The effect of different mixtures of sawdust on the initial growth of P. pseudostrobus var. apulcensis, using the traditional nursery production system was evaluated. A complete random design was used to evaluate four mixtures of substrates of sawdust, forest soil, pine bark, peat moss and agrolite. At age seven and half months the seedlings growing in the 80% sawdust + 20% peat moss mixture yielded the higher values for diameter and height growth, root dry weight, and shoot dry weight, shoot/root ratio, and greater values for the Dickson quality index. For the sturdiness quotient the mixture of 80% sawdust + 20% forest soil had the best values. Raw sawdust can produce healthy seedlings, without any toxicity effects, and it is an alternative material at the nursery. However, it is required to determine the amount of nutriments.

In order to develop a protocol for vegetative propagation of Eucalyptus camaldulensis through the use of stem sprouts, two nursery trials were established in March and May, respectively, to evaluate the effect of IBA concentration (applied with the commercial product Radix®) and genotype on rooting capacity of cuttings, in a substrate made up of peat moss, vermiculite, and perlite (60:30:10). Both trials had the same design, but in the second not all the clones could be included. After five weeks of establishing the nursery trials, cuttings were evaluated in terms of root and callus formation. esults showed that IBA did not affect significantly the percentage of rooting, callus formation, or number of roots; IBA only affected root length in the second trial. However, rooting response varied significantly between the two nursery trials, probably due to differences in environmental or physiological conditions of cuttings during the trials. In addition, significant differences among clones were found for rooting capacity and callus formation, as well as for root length. These results imply that genetic differences in rooting capacity exist among the E. camaldulensis clones included in this study.

T´zalam Lysiloma latisiliquum (L.) Benth. it is the most abundant species in Escarcega, Campeche, Mexico, being the most important economically species in secondary forests derived of a semi-evergreen tropical forest to have been intervened by means of the system slash-and-burn agriculture. The objective of this work is to analyze the behavior of the growth in stem diameter of this species in a 20 year period. Using the variable normal diameter (d1.3) grouped on diametric classes. Annual increments mean, maximum and minimum for each category were considered. Results indicate that in the most advantageous scenario it is required 10.6 years so that the trees go from to profitable and on the average it takes 21.5 years to reach the same condition. The average increment in diameter it is of 0.511 cm and is classify as medium.

The present work was carried out on parcels of natural forests and later on those same parcels taken advantage by total and extracted common pruning the wooden volumes with the employment of tractors of mats, rubbers and animal traction. In both cases like comparison measures of biological diversity were chosen, as the wealth of species, the diversity of species, the number of individuals, of species and the index of uniformity. Later on she was carried out an analysis of double variance, concluding that the employment of tractors of mats for the wooden extraction, was the technology of worse behaviour with relationship to the used indexes.

In this research, 12 forestry species of use in the basketwork of the piaroa ethnic communities of Amazonas states in Venezuela is presented. The basketwork products more commonly used are bags, catumares, a kinds of nose bag, fishers net or fisher`s baskets, fishers`s baskets, carpets, guayares ( anothers kind of nose bags); manares, a kinds of sieve, mapires, petacas, sebucanes, a basket used to extract yuca`s juice, basket and yoperas, used as box to store “yopo” (a kind of drugs). The major usable plants species in this activities were of the Arecaceae (palmae) family, with seven species; while than the families Araceae, Maranthaceae, Annonaceae, Lecythidaceae and Malpighiaceae are represented for only one species each one.

Forestry survay was created by monitor digitizing with AutoCAD Map 2000 for the community of Santa Maria Candelaria, Yautepec, Oaxaca. A digital ortophotograph named E15C81a.TIF, contours data named E15C81cn.dxf, and streams data named E15C81hl.dxf were placed as background to digitize geographic features. A polygon topology named TSBR was created from layers of LIMITE, RODALES, y SUBRODALES. By other way, network topologies named TAGUA y TCAMINO were created from stream and road layers, respectively. Furthermore, automatic and traditional methods were compared, concluding that automatic method is more accurate and more efficient, although not, more economic. Automatic method was more efficient.

For the production of pencil slats the mexican industry uses the sawmilling and slicing methods. This study is the first trial to produce peeling veneer of 5 mm thickness for pencil slats. Pinus ayacahuite Ehr logs were used in four conditioning schedules tests in the laboratory of the Forest Science Division of the Chapingo Autonomous University. The logs were conditioned in tanks with hot water at controller temperatures and the peeling temperature was determined in the pit of the logs at the end of the process. To get the specified veneer thickness, the vertical and horizontal gaps of the knife and nose bar were adjusted to 5 and 2 mm respectively. It was determined that the optimum peeling temperature for Pinus Ayacahite Ehr was from 48 to 52 °C and it is suggested to use water temperatures from 50 to 75 °C in a 20 hours period. The method to produce the pencil slats from peeling veneer overcomes up to 50% the recovery factor of the traditional system of the mexican pencil industry.