The causes of forest degradation are analyzed, examining factors such as climate, acid rain, acid fog, excess or lack of nutrients, pests and diseases, and pollution. Several hypotheses of causes and effects are discussed. In addition, symptoms and damage to tree growth, methods of evaluation, and classification of trees by state of health, and the impact of degradation on adaptive aspects of sensibility, tolerance, and evaluation of tree species are highlighted. Also, it is proposed that the forest cycle in the dynamics of forest degradation be considered.

Rust fungi are obligatorily biotrophic plant parasites that obtain their nutrients from living host cells. During the fungal cycle, three types of intracellular structures (invasion hifae, M-hautoria, and D-haustoria) are formed and each may, in different ways, affect the host membrane that surrounds it, as well as affecting other cellular components. Each intracellular structure also prevents non-specific plant defenses from being triggered by fungal activity, possibly by interfering with the system of signals, rather than with the expression of defenses.

In this study, growth and biomass accumulation of 42 open-pollinated families of three Eucalyptus species (E. globulus, E. resinifera, and E. rudis) were evaluated using seven-month-old seedlings. The progeny test was established under nursery conditions using germplasm collected from plantations in the Valley of Mexico. Results showed significant variation (P≤0.05) among both species and families within species for seedling height and diameter and number of branches and leaves on the main stem, though not for leaf area. At the species level, there were also significant differences in most traits related to biomass accumulation and distribution, except for leaf dry weight. At the family level, a significant variation P≤0.01) was also found for most of the seedling biomass components, except for biomass of branches and roots. Within species, variation (among families) contributed 2 to 12 % of the total phenotypic variation in seedling traits, while the species contributed only 0.5 to 7.5 % of this variation. The largest component of variation was found within families, contributing 80 to 90 % of the total variation for all growth and biomass traits evaluated in the seedlings.

In 1999 and 2000, in Chapingo, Mexico, tests of pathogenicity were conducted on the fungi Cryphonectria cubensis, Lasiodioplodia theobromae, and Fusicoccum sp. Two-year-old Eucalyptus camaldulensis plants were inoculated with strains of these fungi and kept in a greenhouse with a temperature range of 25-29 °C and natural relative humidity. Inoculation was done at two points: at the base and at the upper part of the trunk, using methods of insertion and puncture. Lasiodioplodia theobromae required 7 to 12 days for the appearance of the first pycnidia and 12-15 days for initial emission of conidia. The fungus caused the plants’ death within two months, during which it colonized the entire trunk. Cryphonectria cubensis required 57-63 days to cause the death of the tree; pycnidia formed 33-56 days after inoculation, and conidia were released at 56-60 days. Fusicoccum sp. caused the death of the inoculated plants in 63 days and required 50-54 days for the formation of pycnidia and 60-63 days for the first emission of conidia. Pycnidia and conidia of each of the fungi were measured, and this data was compared with data found in the literature; the species and genera were corroborated.

In this study, a model was selected to determine indexes of fire risk in temperate forests in Mexico, by estimating the speed at which fires spread. A linear regression statistical model was developed using the variables of the temperature and moisture content of sample branches of Pinus patula and Pinus montezumae. A coefficient of determination of 0.97 was obtained. For the classification of the index of fire risk, the following parameters were used: speed of propagation, temperature and moisture content of Pinus patula and Pinus montezumae. The data base comprises information from a year of controlled burning with these variables. With these values, a table of ranges or degrees of risk was generated, and five degrees of fire risk were defined (null, low, moderate, high, and extreme).

The imminent rise in the cost of raw material used by the forest industry in the Dominican Republic requires volumetric tables that are capable of estimating, as precisely as possible, the volumes of trees and stands that provide the raw material. Accuracy in the estimation is essential for the rational planning of forest management. This study presents an equation for the estimation of volume, which was later used to create a table of cubic quantities of wood stands of Pinus occidentalis Sw., which are used and managed within a plan of reordering of natural forests by Plan Sierra in its area of influence. The equation obtained in this study is compared with that generated by Gil and Cuevas (1986) used for the construction of the cubing table used for 14 years. It is intended to substitute the existing table, for which the samples were taken from stands of trees that possess specific characteristics and differ in their development (They are smaller and thinner) and in soil and climate from the rest of the area of influence of Plan Sierra. The sample for the existing table was 40 trees, while, for this study, we sampled 191 trees representative of the three different zones that occur in the Sierra.

For eight years34 extraction forests have been controlled directly in Spain. This control consists of thinning in reforested plantations, usually composed of Scots pine (Pinus sylvestris L.). Information was collected on material equipment and human resources, risk of accidents and health, safety measures and incidents that occurred over more than 2200 hours timed in the various operations of extraction of around 3000 hours spent in the field. The study reveals the deficiencies of the active and passive equipment used by the teams, placing special emphasis on jobs done manually, for which there is a lack of training, low pay, and absence of real plans for the safety and health of the workers in forest extractions. With respect to health risk, in manual work, the disorder Traumatic Vasospastic Disease, produced from the vibrations of the chain saw, and the Leyme Disease, caused by ticks, have been long considered health risks in many European countries, but in Spain the real danger of these diseases has not been recognized.

The National Accounting System (Sistema de Cuentas Nationales-SCN) that is in force and measured by the Gross National Product (GNP) evades environmental issues and the degradation and depreciation of natural resources, and thus reflect rates that overestimate economic growth. This paper discusses the SCN, its limitations in the quantification of the degradation of natural resources as capital and environmental impact. Experiences in other countries are presented, and the development of a national accounting system that includes natural resources is promoted.

The bank financing for forestry is very restricted, mainly for the enterprises of the social sector that don’t have mortgage guarantees to support the credits when those present viable and profitable projects. To face this situation, a proposal to constitute funds and that later on the banking takes them as guarantee for the grant of credits, that is to say, to guarantee credits with cash on the part of the applicants was done. The attractive of this scheme is that the enterproses that require financing, with so alone to gather 30% of their necessities, they can have access to the credit. Other advantage of the proposal, it is that for the formation of the funds they can make contributions all the participants of the productive process, situation that benefits the financing applicants since is not the only ones that run the risk of the investments, but all those that contribute to the bottom.

Forest and woody agricultural residues constitute potential resources with interesting possibilities for technological use, among which is highlighted their use in thermochemical processes, combustion, gasification, and pyrolysis. The appraisal of energy of a given material should be considered a basic element of its heat potential. In this paper, results are presented of a study of the possibilities of energetic use of diverse forest residues that are abundant in the province of Pinar del Río, such as Pinus caribaea Morelet var. Caribaea (Pc) and Pinus tropicalis Morelet (Pt), wood of eucalyptus: Eucalyptus saligna Smith (Es), Eucalyptus citriodora Hook (Ec) and Eucalyptus pellita F. Muell (Ep), carbonized sawdust prepared on a laboratory scale at a temperature of 700 °C for two hours and plant carbon from Pinus caribaea Morelet var. caribaea (Costanera) (PcC) prepared in an oven, and other natural wood species such as Dicrostachys cinerea Wight & Arm. (Marabú) (Dc), Conocarpus erecta L. (Yana) (Ce), Quercus oleoide C. y S. var. Sagreana C.H. Mull (Encino) (Qo), and Guasuma tomentosa HBK (Guásima) (Gt).

The present study was carried out to widen the knowledge of the technological characteristics, tension wood and pulp & paper indexes of Dendropanax arboreus (L) Planch & Decne., This study included anatomical features, both macroscopic & microscopic, determination of density, shrinkage & swelling. Strength properties were derived from different relationships between the various strength properties and wood density. Regarding tension wood, a staining section technique was used to detect it. Results of the anatomical features showed that vessel elements have a scaliform perforation plate with an average length of 959.48m and an average diameter of 73.31μ. The fibres have an average length of 1343.73μ, an average diameter of 27.73μ & an average cell wall thickness of 4.68μ. This wood has a medium basic density (0.44 g/cm), medium volumetric shrinkage (11.17 %), high lineal shrinkage (7.0 T & 4.14 % R), low anisotropy relationship (1.69), good pulp & paper indexes, and low to very low strength properties. Tension wood was found isolated and scattered. In analyzing the general behavior of the anatomical features, the strength properties & the pulp & paper indexes, it was not observed any tendency at different diameters or heights of the tree. Is concluded that Dendropanax arboreus wood can be used in a wide range of uses, but it is not suitable for structural uses.

Wood used on exteriors requires products to protect it from weathering and, in some cases, to improve its appearance. In film-forming finishes, cohesion failures occur between the word and the film because of solar radiation and humidity, resulting in whitening and peeling. In this study, two commercial polyurethane varnishes for exteriors were tested. One was water based (Hydroform®) and the other was solvent based (11000®). The varnishes were applied on oak and pine and then subjected to accelerated weathering (CTBA of France). According to the manufacturers, when a 10 % failure of the appearance is reached, re-varnishing is recommended. The obtained data were fit to a Weibull accumulative distribution to estimate the time at which this failure occurs. Considering that 2.25 hours of accelerated weathering is equivalent to a day of natural weathering under drastic conditions, the estimated time to the recommended re-varnishing was 15.76 days for pine and 76.21 days for oak when varnished with Hydroform®, while with 11000® time to re-varnishing was 544.26 days for pine and 381.15 days for oak.