German Flores - Academia.edu (original) (raw)

Papers by German Flores

Notes, 2006

The implementation of silvicultural strategies in a forest management has to guaranty forest sust... more The implementation of silvicultural strategies in a forest management has to guaranty forest sustainability, which is supported by an adequate regeneration. Therefore, quality and intensity of silvicultural practices is based on an accurate knowledge of the current spatial distribution of regeneration. At the same time, this regeneration is determined by the spatial distribution of many disturbing factors, such as fuel loadings, trees density, and grazing. However, regeneration mapping is not considered very often because its evaluation is both time and cost consuming. As a practical alternative, this study shows the results of a spatial evaluation of trees regeneration, where spatial distribution of regeneration is modeled. The data was obtained from 79 sample plots systematically distributed in a watershed of 1000 ha., at the saw of Tapalpa, Jalisco (México). Two interpolation alternatives were tested and compared: a) Inverse Distance Weighting [IDW]; and b) Ordinary Kriging (simple stochastic interpolation). Individuals between 0.30 and 2.5 m of height represented tree natural regeneration. The results showed that geostatistics technique (OK) was better in 50 percent of the cases, and deterministic technique (IDW) was better for the rest 50 percent. This suggest that not single interpolation technique has to be used in all situations. The results would support silvicultural strategies. It is suggested in further studies to use ancillary data, such as tree density, fuels, slope, and species distribution.

Agro productividad, Jan 17, 2023

Objective: bamboo is a forest resource that, due to its rapid growth, requires frequent evaluatio... more Objective: bamboo is a forest resource that, due to its rapid growth, requires frequent evaluations (monitoring) to define the most appropriate management strategies; however this entails a high cost and a great investment of time. This study presents an analysis of the use of unmanned aerial vehicles (UAVs) to generate information on the crown cover of Guadua spp. bamboo strains, and relates it to other of its dasometric parameters. Methodology: the areas of the bamboo strains were defined based on generated aerial images, where each strain was delimited by differentiating it from its environment, for which four types of thresholds were defined. Results: the relationship of the crown area with each dasometric parameter suggests that there is a positive trend, where in most cases there was an adequate significance (P0.05): height R 2 0.67 (P0.0222); diameter 1.3 m R 2 0.56 (P0.0367); culm diameter 0.3 m R 2 0.57 (P0.0313); and number of culms R 2 0.54 (P0.130). Conclusions: in this way, the results showed that with the UAV it was possible to determine the coverage area of individual bamboo strains and that some of their dasometric parameters could be estimated based on their allometric relationship.

Open Journal of Forestry, 2023

Revista mexicana de ciencias forestales, Apr 23, 2021

Several allometric equations were generated for biomass and carbon content for Cedrela odorata tr... more Several allometric equations were generated for biomass and carbon content for Cedrela odorata trees. Twentyseven trees were selected from tree different forest plantations in the states of Jalisco and Colima. The best trees were carefully chosen for felling, partitioning, and measuring in the field. Samples from the stem, branches and foliage were collected and sent to the laboratory in order to estimate their biomass and carbon content. The results from each sample were used to the different sections of the tree. Some models were tested, and the final potential model used was = • ; the allometric biomass equation is AB=0.00341•ND 3.38248 , and for carbon content is CC=0.001562•DN 3.389696 ; where: AB is the aboveground biomass (kg); and CC is the aboveground carbon content (kg), ND is the normal diameter (cm). Both equations exhibited a good fit with an R 2 of 0.978, and the tests of normality, heteroscedasticity and independence, show good confidence and guarantee of the models developed. The results suggest that the equations generated allow estimating the aerial biomass and the carbon concentration based on the normal diameter.

E-Cucba, Dec 22, 2022

Simulación de las variaciones de la velocidad de propagación del fuego, durante una quema prescri... more Simulación de las variaciones de la velocidad de propagación del fuego, durante una quema prescrita Simulation of variations in the speed of fire propagation, during a prescribed burn

Revista Internacional De Contaminacion Ambiental, 1996

Soil chemical changes due to fire when prescribed burns are applied in a temperate forest of mexico

Este trabajo se enfoca a la necesidad de contar con una metodología alternativa en la simulación ... more Este trabajo se enfoca a la necesidad de contar con una metodología alternativa en la simulación del comportamiento del fuego. Ésta se basa en el mapeo de combustibles forestales, como opción al concepto de modelos de combustibles que tradicionalmente se ha usado. Se usaron tres mapas correspondientes a la distribución de tres clases de combustibles, los que se clasifican con base al tiempo en el que, por su tamaño, los combustibles muertos ganan o pierden humedad hasta estar en equilibrio con el aire que los rodea (1-h, 10-h y 100-h). La generación de estos mapas fue a través de la evaluación y la comparación de técnicas de interpolación tanto determinísticas como estocásticas. Esto permitió una mejor definición de la variación espacial de combustibles, incluso dentro de una misma zona clasificada con un determinado modelo de combustible. En general, las técnicas geoestadísticas (específicamente co-kriging) fueron la mejor alternativa. La elevación fue la variable más relevante en las estimaciones al usar co-kriging, la que se obtuvo a través de un modelo de elevación digital. Los datos de campo fueron inventariados en 554 sitios, en un área aproximada de 1,400 ha, en el ejido El Largo y Anexos, de Chihuahua. Posteriormente se generó un modelo espacial de simulación

Investigaciones Geográficas, Boletín del Instituto de Geografía, Nov 30, 2021

• ARTÍCULOS Núm. 106 • Diciembre • 2021 • e60396 www.investigacionesgeograficas.unam.mx Análisis ... more • ARTÍCULOS Núm. 106 • Diciembre • 2021 • e60396 www.investigacionesgeograficas.unam.mx Análisis comparativo de índices espectrales para ubicar y dimensionar niveles de severidad de incendios forestales Comparative analysis of spectral indices to locate and size levels of severity of forest fires

Journal of Environmental Protection, 2018

Fuel model mapping has followed in general two trends: 1) indirect inferences, where some factors... more Fuel model mapping has followed in general two trends: 1) indirect inferences, where some factors, presumably associated with fuel production, are related to a given fuel model; and 2) experts consulting, which has been used to classify and to validate other people classifications. However, reliance on expert judgment implies a subjective approach. Thus, I propone the integration of geostatistic techniques and the Conditional-Fuels-Loading concept (CFL) to define a more objective perspective in the fuel-model mapping. The information used in this study was collected in a forest of Chihuahua, Mexico, where fuels were inventoried in 554 (1000 m 2) sample plots. These sample plots were classified using the CFL; and ordinary kriging (Gaussian, spherical and exponential) was used to interpolate the fuel-model values. Using the Akaike's Information Criterion the spherical model performed best. The methodology allowed a finer definition of spatial distribution of fuel models. Some advantages of the CFL are: 1) it is based on actual fuel loads, and not only on vegetation structure and composition; 2) it is objective and avoids the bias of different classifiers (experts); and 3) it avoids the need of the advice of experts.

Open Journal of Forestry, 2018

In Mexico, forest ecosystems are disturbed by fires and generally these are considered to have ne... more In Mexico, forest ecosystems are disturbed by fires and generally these are considered to have negative impacts. However, it is important to consider that fire is an element of these ecosystems, and is important for its functionality. So it should be understood that in many cases the effects of a forest fire are beneficial, which can be determined through studies of population dynamics of these ecosystems. However, most of these studies currently focused only on aspects of species composition, with few cases concerning the analysis of the structure and density. In this study, a comparative analysis of the vegetation showed that conditions prevailing between burned and unburned areas of a site covered by microphyll desert species (shrubs and mesquite). The results suggest that the structure and density conditions of vegetation between burned and unburned areas are not statistically different. This is highlighted because one year after the fire occurred there is no evidence that fire had altered the structure and density of vegetation. Moreover, both in burned and unburned areas, vegetation had a healthy condition. Finally, although this may suggests that the fire was of low intensity, which resulted in a low impact on vegetation, in future studies it is recommended to determine if the same results are observed under different possible fire behavior and intensity.

Agrociencia, May 1, 2005

Forest fuels are one of the main factors that define an adequate establishment and development of... more Forest fuels are one of the main factors that define an adequate establishment and development of forest regeneration. Therefore, in this study, the spatial relationship between regeneration, establishment and presence of forest fuels is modeled. The data was obtained from 79 sample plots systematically distributed in a watershed of 1400 ha at Tapalpa, State of Jalisco, México. Based on dominance, six regeneration classes were defined. Three interpolation alternatives were tested and compared: Inverse Distance Weighting (IDW), Ordinary Kriging (simple stochastic interpolation) and Cokriging (multivariate stochastic interpolation). For Cokriging, nine fuel variables were defined. Individuals between 0.3. and 2.5 m of height represented natural tree regeneration. Geostatistics techniques (mainly Cokriging) showed the best results; however, in one case IDW was better. No single interpolation technique has to be used in all situations. The results will support fuel management strategies.

Revista Chapingo serie ciencias forestales y del ambiente, Aug 31, 2018

Introduction. The mapping of areas with higher forest fire density can be developed through kerne... more Introduction. The mapping of areas with higher forest fire density can be developed through kernel density estimation, which requires the selection of a function and bandwidth (h). The h value, when defined by subjective (visual) processes, will depend on the knowledge and experience of the person making the selection. Objective: To propose a statistical alternative, based on forest fires information (2005-2013) from Jalisco, Mexico, for the selection of h as support for kernel density estimation. Materials and methods: A total of 13 h values were defined using seven techniques. The h value was selected using the following statistics: root mean square error, root mean integrated squared error, coefficient of variation and comparative percentage. Results and discussion: The h values obtained with the techniques analyzed were between 2 550 and 41 906 m. There was great variation in the results; the range between the maximum and the minimum value was 39 356.34 m with an average of 10 936.74 ± 9 955.04 m. The above implies that there is no single and universal process for all cases. According to the validation criteria, the statistically most adequate h value is between 5 300 and 5 900 m; the closest result was obtained with the mean random distance technique (5 395 m). Conclusion: It is possible to select h under a practical statistical perspective, avoiding the use of subjective criteria. Resumen

Tecnología y ciencias del agua, 2018

In various parts of the world, the decrease in dissolved oxygen (DO) in the lakes has affected ne... more In various parts of the world, the decrease in dissolved oxygen (DO) in the lakes has affected negatively their quality. In Mexico, the Chapala Lake is the most important water body, since it has a transcendental role in the productive development of the region. Nevertheless, is also one of the most polluted bodies of water, therefore, the monitoring of the water quality is an important issue for its management. However, time and cost, involved in a constant sampling, are some of the main limitations for such monitoring. Therefore, we used alternative methodologies based on geostatistical approaches. In this way, we studied the OD spatialtemporal continuity of OD, through interpolations defined with ordinary kriging. The results showed that it was possible to model the variation spatial-temporal of OD concentrations, both along the Lake of Chapala, as at different depths. However, in some cases, the variograms presented a spatial trend at a global level. Therefore, in future work, we suggest to modeling OD based on universal kriging.