There is a consensus that anthropogenic actions are degrading ecosystems at an alarming rate. Modeling and new technologies, such as information and communications technology (ICT), are increasingly being used to make decisions about the management and conservation of natural resources. In this study, the temporal evolution and spatial distribution of Mexican scientific production in forest modeling are analyzed. From 1980 to 2015, 454 authors participated in the publication of 259 papers in 37 journals (84 % of them Mexican), of which 28 are indexed in the Journal Citation Reports (JCR). Studies on forest management have been the most important but are losing relative weight, while those on environmental services and potential distribution of species are gaining importance. The authors belong to 89 institutions, of which 65 % are Mexican. During the period analyzed, the number of authors (and partnerships) increased 12 times, while the number of publications increased nine times. These increases coincide with the evolution of regulatory policies and the establishment and support of the National System of Researchers. Collaborations in the current forest-modeling network still have great growth potential.

Systematic reviews are important tools for objective literature research, composition and critical analysis of variant studies results, with an excellent contribution in clarifying issues and searching for new research directions. This study aims the systematic review of independent studies of volume estimation for Scots pine (Pinus sylvestris) in Europe. A meta-analysis of individual tree volume estimation models was performed. The stages of meta-analysis, statistical methods, possible errors arising, and heterogeneity that occur among studies are described in detail. Results showed that Italy is clearly distinguished (volumes are too small), Greece and Sweden present large volumes, and there is great heterogeneity among studies, probably due to different competition conditions created in stands in different countries of Europe, not different climate. More research could be useful in Italy, and in Greece, a study with a larger sample size could contribute to the promotion of research.

In Mexico, several reforestation programs have been launched; they generally fail to achieve good survival rates, mainly due to drought. To mitigate this, technologies that help plants survive in the early years should be generated. In light of this, the effect of adding water reservoirs at transplanting on survival, height, diameter and biomass of Pinus leiophylla plants, grown under simulated drought conditions in a greenhouse, was evaluated. Plants were arranged in a completely randomized design and four treatments were used: control, a 231-cc phenolic foam block, a 308-cc phenolic foam block and three grams of hydrogel, all hydrated with tap water. A survival analysis was performed, yielding significant difference between control and the other treatments (P = 0.000008). No statistically significant differences were found in height. Statistically significant differences were found in diameter among treatments at 8 (P = 0.013) and 12 weeks (P = 0.002). Statistically significant differences were detected in biomass among treatments (P = 0.0001). Adding hydrated opencell phenolic foam at transplanting significantly increased survival time and diameter of P. leiophylla under drought conditions.

In Ensenada Baja California, ships and vehicles produce particles with heavy metals. These particles are blown by the wind and deposited on the soil becoming urban dust. Heavy metals may affect the health of the population, so a quick diagnosis is required to find a solution to this problem. The aim of this study is to identify those areas of higher pollution within the city. A total of 86 urban dust samples were sampled on diferent substrates (soil, cement and asphalt). Heavy metals were analyzed by X-ray fluorescence. Differences among substrates were identified by analysis of variance. The analysis of ordinary Kriging interpolation was performed to estimate the spatial distribution of heavy metals. Asphalt contains higher concentration of Cr, Ni, Pb and Zn; cement contains higher concentrations of Cu and V; and soil contains higher concentrations of Rb. The map which includes the classes with higher concentration of heavy metals shows that the southwest area of the city is the most polluted area due to port and transpeninsular highway

The production of oregano plants in nursery is an option for the production of high quality transplanting plants. The purpose of this study was to evaluate the effect of five growing media mixtures and five types of containers on the growth and quality of oregano plants. The growing media mixtures consisted of the commercial mixture BM2 (peat moss, perlite and vermiculite 80:10:10), BM2 with river sand (1:1), BM2 with river sand (1.5:1), BM2 with perlite and vermiculite (1:1:1) and a mixture of compost with river sand (1.5:1). The containers included expanded polystyrene trays of 200, 128 and 76 cavities, 250-mL polystyrene pots and 712-mL black plastic bags (caliber 150 μm). A randomized complete block design with factorial arrangement of treatment with four replications per treatment was used. The growing media and the type of container affected the growth and quality of the plant. Higher plant growth and higher leaf area was observed in the combination of bag and growing medium BM2, which led to the highest Dickson quality index. Shoot and root dry weight ratio was higher in larger volume containers.

The growing deterioration of natural resources creates the need to value ecosystem services, including biodiversity. The economic value has focused on non-market goods and services, which is complicated. Techniques have been developed to measure these values whose acceptance has increased lately. A search of economic valuation made in Mexico was conducted. Almost all valuation studies undertaken in the country are restricted to travel cost (TCM) and contingent valuation (CVM) methods. The only level of biodiversity explored was at level of ecosystem. At the level of gene or species no studies have been developed in terms of non-market goods and services. The most widely valuation method used is the contingent valuation (11 studies), followed by the travel cost method with one study, which was conducted along with the CVM. Eight studies did not consider the most important biases (time, substitution, multiple destinations, payment instrument, strategic and hypothetical) of these methods.

Historical fire regimes were reconstructed using dendrochronological methods to provide basic information for understanding this phenomenon. In order to reconstruct the fire history in a pine-oak forest in Mezquital, Durango, we collected 78 samples from different fire-scarred tree species (Pinus durangensis, P. arizonica, P. ayacahuite, P. teocote and Pseudotsuga menziesii); 73 and 27 % of the samples were taken from live and dead trees, respectively. By applying dendrochronological methods a total of 75 samples (96 %) and 535 fire scars were dated. Fire regimes were reconstructed from 1746 to 2013, with 1779 being the year of the first recorded fire. A mean fire interval (MFI) of 2.0 years and a Weibull median probability interval (WMPI) of 1.8 years (all scars) were reconstructed. Considering 25 % of scars or more (large fires), a MFI and a WMPI of 7.0 and 5.9 years, respectively, were determined. In total, 92.2 % of fires were categorized as having occurred in the spring and only 7.8 % in the summer. There was no significant (P < 0.05) influence of rainfall and the El Niño Southern Oscillation (ENSO) on fire frequency; however, extensive fires were positively associated with decreased rainfall and ENSO events (La Niña phase).

El cambio de uso del suelo de la ciudad de Villahermosa, Tabasco, se analizó con base en el efecto provocado por el crecimiento urbano sobre la vegetación arbórea y los ecosistemas acuáticos. Se hizo un análisis multitemporal mediante el modelador de cambio de uso del suelo (Land Change Modeler for Ecological Sustainability) y el módulo CrossTab del software IDRISI Selva® y se calcularon tasas de cambio. De acuerdo con los resultados, durante casi tres décadas (1984-2008) se perdieron 4,008 ha de suelo ocupado por vegetación arbórea y 289 ha de humedales, debido al crecimiento acelerado de los pastizales y la zona urbana. Mediante modelos de transición estocástica (cadenas de Markov y autómatas celulares) se proyectó una pérdida de 1,171 ha de vegetación arbórea y 247 ha de humedales entre el periodo 2008 y 2030. Es probable que esta tendencia se mantenga por el incesante crecimiento del pastizal y la zona urbana.

The increase in industrial forest plantations in southern Chile and the alteration of the landscape have been an ongoing concern of researchers. In this paper, spatial statistical techniques were used to describe the composition of the territorial patterns of forest plantations, in an area with a pulp mill and with high demand for exotic species such as Pinus radiata and Eucalyptus. GeoDa software was used to calculate global and local Moran indexes. Land-use cover data and the area of the forest plantation polygons updated in the period 2006- 2013 were used. The global Moran index indicates that plantation distribution occurs as a random phenomenon throughout the territory. In its interior there are different structures, represented by enclaves of large areas, small polygons surrounded by others of great size and large polygons surrounded by small ones, as well as a fragmentation throughout the territory, composed of polygons of various sizes and neighborless. The dynamics of change in the period 2006-2013 indicates that plantation cover presented the largest increase (6,578 ha) due to the reduction in native forest and grassland-shrubland covers.

Traditional fruit homegardens are units of production of high richness of species with value in use. The objective was to analyze the relationship between the arboreal structure of 30 homegardens of Coatetelco, Morelos and the value in use of the species. The structure was quantified through the Importance Value Index (IVI). The Cultural Value Index (CVI) identified the preference of the community. The arboreal variety includes 24 botanical families, 49 genera and 65 species; 45 % were introduced and 55 % were native of America from which 23 % belonged to dry tropical deciduous forest. Ecologically and culturally, the most important species are the multiple use ones (Leucaena leucocephala, and L. esculenta), self-supply and sale ones (Mangifera indica, and Citrus x aurantium), and the ones produced during dry season (Spondias purpurea and Pithecellobium dulce). The size of homegardens, specific richness and density are positively related. Importance value and cultural value index correlated 86 %. The structure of the homegardens was organized because of cultural reasons. The preferred species are the ones with the highest value in use. Native trees such as Amphipterygium adstringens, Swietenia humilis, Jacaratia mexicana, Enterolobium cyclocarpum and also some other species introduced as Citrus maxima, Ficus carica and Moringa oleifera which could be lost because of lack of space.