Search

Biodiversity conservation is a priority because it is the cornerstone of ecosystem services and natural cycles, providing essential resources for the development of humans and other species. Several indices have been proposed to prioritize areas needing protection. However, some require specific information while others are based on subjective categorical variables, are limited to a particular plant community or cannot be represented at a spatial scale. We developed an Index of Importance for Biological Conservation (InICoB), which was applied to a temperate forest in central Mexico but can be used for any plant community by adjusting some of its parameters. The proposed index is objective, based on quantitative indicators of vegetation composition and structure, and can be spatially projected. InICoB was tested and validated on a temperate cloud forest (CF) and its associated communities: advanced secondary vegetation (ASV) / coffee plantations (CP), agriculture, and induced grasslands. Life forms, presence of endemic, climax, native and protected species, diversity, structural complexity, and complementarity were used as indicators in its construction. InICoB was calculated for 63 sampling units (SUs), and a geostatistical model was incorporated for its interpolation with environmental and social variables as predictors. The results show that InICoB adequately evaluated the different environmental units that cover the locality. Significant differences were observed between the forest and the secondary/induced vegetation. The highest value of InICoB (0.91) was found in the CF, and the lowest in induced vegetation (0.3). The geostatistical model showed that occupation of the land, distance to town, and slope have an important influence on InICoB. The advantages of InICoB include the use of quantitative indicators that can be applied to any plant community. Additionally, it is flexible with respect to the data collected, it can be calculated only with the presence/absence of species or it can include forest measurement data. Furthermore, it is easy to interpret and can be spatially represented in a raster layer that can be added to a geographic information system. Therefore, it can be a very helpful tool in decision-making for land use planning and evaluation of the effects of human activities on plant communities. [ABSTRACT FROM AUTHOR]

Biometric systems are the basis of forest management and consist of a set of equations that describe the relationships between forest attributes and dendrometric variables. A systematic review of the state of the art of biometric systems in Mexico was carried out by a Mexican consortium (10 researchers), covering a period of 50 years ca (1970–2019), using the main scientific literature delivered by a systematic search (WoS, Scopus, Scielo, Redalyc) and a targeted search (theses, technical reports, etc.). A single selection criterion was established for the inclusion of information in the analysis: the document had to present at least one of the equations of interest. We found 376 documents containing 2524 equations for volume (69%), diameter (11%), height (9%) and site index (11%). These equations were developed for forest species mainly from temperate regions (88%), such as pine (66%) and oak (9%). Consequently, the Mexican states with the highest number of equations were Durango (28%), Chihuahua (17%), Hidalgo (13%) and Oaxaca (8%). Although large, the number of equations identified concentrated on a relatively small number of models: Schumacher & Hall and Fang et al. for volume; Chapman-Richards and Schumacher for site index and diameter; and Chapman-Richards and the allometric equation for height. An analysis of model fit, measured through R2, showed that, on average, the volume, diameter and site index models show high fit (R2 = 0.96), although this pattern was more consistent in the volume models. Publication bias was evaluated by means of a funnel plot analysis, with no apparent bias identified. A limitation of our study is that the information obtained is not updated to the present year; however, the 50-year trends allow us to assume that no recent significant changes in the patterns exist. Finally, we highlight the need to assess the predictive ability of the models to ensure accurate estimates to support better forest management decisions. [ABSTRACT FROM AUTHOR]

Copyright of Revista Chapingo Serie Ciencias Forestales is the property of Universidad Autonoma Chapingo and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revista Chapingo Serie Ciencias Forestales is the property of Universidad Autonoma Chapingo and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revista Chapingo Serie Ciencias Forestales is the property of Universidad Autonoma Chapingo and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revista Chapingo Serie Ciencias Forestales is the property of Universidad Autonoma Chapingo and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Modeling of dominant height growth and site index is a valuable tool for classifying productivity of forest lands and for defining forest management strategies; station quality is a criterion for defining the programming of forest interventions. The derivation of a dynamic equation is presented from the base model of Chapman-Richards, considering the parameter of the asymptote and of the exchange rate as a function of site quality. The dynamic equation obtained has complex polymorphism and multiple asymptotes, and was fitted for Pinus arizonica, P. durangensis, P. teocote, P. leiophylla and P. ayacahuite as a group and by species with dummy variables, and was compared with two GADA equations, with the same number of parameters. These are based on the models of Chapman Richards and Korf, which have been used in the modeling of dominant height and site index. The comparison indicated that the derived equation presented better parsimony in the algebraic expression that describes the productivity of the site and considered the variability of the potential of the site as a function of the asymptote. The dynamic equation can be used to predict dominant height growth and site index for the mixed stands of the study area, with similar growth rates for Pinus durangensis, P. ayacahuite and P. arizonica, that responds to the degree of association among these species; Pinus teocote and P. leiophylla present the lowest growth rates. [ABSTRACT FROM AUTHOR]

The estimate of the merchantable and total volume is an essential tool in the forest planning and management, so the aim of this study was to evaluate three segmented systems of taper and merchantable volume with bark fitted as simultaneous equations for data from commercial forest species of Durango, Mexico. Fittings were made from three perspectives: 1) for each species in the three systems, 2) global fittings combining all species (reduced model) and 3) overall fit considering dummy variables (full model). Fitness of compatible systems of taper and merchantable volume suggest that studied species present two inflection points; the dendrometric shape from neiloide to paraboloidal, on average for the species studied, happens at 5 % of the total height, whereas the change from paraboloid to cone occurs at 73 %. System 3 (S3) has better qualities of fit between the analyzed systems and the full model with indicator variables with additive effects on Pinus durangensis Martinez was better than the reduced model. With the full model, Pinus ayacahuite Ehrenb presents the less cylindrical stem; Pinus arizonica Engelmannii presents the more cylindrical boles, whereas P. durangensis Martinez, Pinus leiophylla Schlecht et Cham and Pinus teocote Schlecht et Cham have a similar paraboloidal shape. The full model makes efficient the fit of the compatible system, all data in the fit process are used and standard errors of the parameters are reduced. [ABSTRACT FROM AUTHOR]

A dominant height growth model and corresponding site index expression, allows estimating the productivity of forests stands and helps define the silvicultural management regime. The aim of this study was to develop, using data from permanent plots, a base-age invariant growth model for dominant height for Tectona grandis L. f. (teak) plantations at Campeche, Mexico. The base growth models used were those of Korf, Chapman-Richards and Hossfeld IV, which were reformulated as generalized algebraic difference equations to define the best site index structures. They were fitted under least squares with a data structure of non-overlapping pairs. To estimate the dominant height growth and classify plantation productivity, the dynamic equation type Chapman-Richards was selected based on the goodness of fit and similarity between the pattern of growth curves and observed trends. To improve the accuracy of the estimates this equation was fitted as a mixed effects model, correcting for heteroscedasticity and autocorrelation. The selected model is flexible and describes a pattern of polymorphic curves with multiple asymptotes, desirable characteristic to model a wide variety of growth patterns. Three specific growth patterns for the analyzed planting sites were detected. [ABSTRACT FROM AUTHOR]

Key message: More accurate diameter at breast height (dbh)-growth models are needed for developing management tools for mixed-species forests in Mexico. Individual distance-dependent dbh growth models that quantify local neighborhood effects have been developed for four species groups in such forests. The performance of the models is improved by distinguishing between inter- and intraspecific group competitions.Context: The management of mixed-species forests in the northwest of Durango, Mexico, is mainly based on the selection method. Understanding the interspecific and intraspecific competition is critical to developing management tools for such mixed-species forests.Aims: An individual-based distance-dependent modeling approach was used to model the growth of dbh and to evaluate neighborhood effects for four species groups in Mexican mixed-species stands.Methods: Twenty-two species were classified into four groups: Pinus (seven species), other conifers (three species), other broadleaves (four species), and Quercus (eight species). Four methods were used to select neighboring trees and 12 competition indices (CIs) were calculated. Comparisons of the neighboring trees selection methods and CIs and tests of assumptions about neighborhood effects were conducted.Results: Intra-species-group competition significantly reduced diameter growth for all species groups, except for the Quercus group. The Pinus, other conifers, and Quercus groups had significant and negative neighborhood effects on the other broadleaves species group, and not vice versa. The Quercus group also had negative neighborhood effect on the Pinus and other conifers species groups, and not vice versa. The Pinus and other conifers species groups had negative neighborhood effects on each other. All fitted age-independent dbh growth models showed a good of fit to the data (adjusted coefficient of determination larger than 0.977).Conclusion: The growth models can be used to predict dbh growth for species groups and competition in mixed-species stand from Durango, Mexico. [ABSTRACT FROM AUTHOR]