Abstract:Se analizó la estructura y la diversidad arbórea de bosques templados del centro de México, se realizó un inventario forestal en tres comunidades de asociaciones arbóreas diferentes (bosque de pino-BP, bosque de aile-pino-BHP, bosque de pino-encino-BPQ), y se establecieron de manera aleatoria 50 sitios de 500 m2 en cada una. Las variables dasométricas obtenidas fueron altura total y diámetro normal ≥ 7.5 cm. Para cada comunidad se analizó la distribución diamétrica, se estimó el índice de valor de importancia,… Show more
“…La heterogeneidad en la estructura del arbolado es de gran importancia, debido a que permite mayor diversidad al incrementar el espacio de nicho, lo que posibilita que se establezcan más especies (Oettel y Lapin 2021), principalmente aves (Hanle et al 2020) e insectos (Staab et al 2023). Los valores del índice de Pretzsch en los tres intervalos altitudinales no mostraron un comportamiento ascendente o decreciente relacionado con la altura, la distribución de especies en los tres estratos de altura de cada intervalo es de alta homogeneidad, ya que un valor del 100% indica que todos los taxones de la comunidad se distribuyen de manera equitativa (Caballero-Cruz et al 2022). El análisis de la estructura vertical presentó resultados superiores a lo reportado por diversos autores como Graciano-Ávila et al (2020) quienes estudiaron una comunidad con dos tratamientos silvícolas en 10 años (2007 al 2017) durante tres periodos de tiempo, señalan valores de A entre 2.66 a 2.72, Amax de 3.87 y Arel de 68 al 70%; al igual Alanís-Rodríguez et al (2020) citan un valor de A = 2.03 y Amax = 3.29 lo que representa una diversidad media en altura para un bosque de galería en una etapa madura sin alteraciones antropogénicas aparentes.…”
Understanding forest structure and diversity allows the development and analysis of strategies for the sustainable management of natural resources. The objective of the research was to contribute to the knowledge of tree structure, as well as its regeneration capacity in an altitudinal gradient in a Natural Protected Area in Madera, Chihuahua. The study included three altitudinal intervals: lower (2 307 to 2 466 m), middle (2 466 to 2 625 m) and upper (2 625 - 2 785 m), in which 30 circular sites of 500 m2 were distributed where the diameter and height of the upper trees were measured, as well as the density of regeneration. The vertical structure was obtained with the Pretzsch index (A), in addition, the importance value index (IVI), diversity with the Shannon-Wiener index (H') and richness with Margalef (Dmg) were evaluated, as well as the renewal capacity and damage present. The values of A show the greatest structural homogeneity in interval 2; the Pinaceae family registered the highest ecological weight in the IVI; the values of H' and Dmg were higher in stratum II, however, all are considered of low diversity and richness; the species Abies concolor and Pseudotsuga menziesii, showed the highest proportion of regeneration in the community, in which suppression is the frequent damage, however, 95% of the individuals were not affected. This information is useful for the conservation of these ecologically important communities in temperate forests.
“…La heterogeneidad en la estructura del arbolado es de gran importancia, debido a que permite mayor diversidad al incrementar el espacio de nicho, lo que posibilita que se establezcan más especies (Oettel y Lapin 2021), principalmente aves (Hanle et al 2020) e insectos (Staab et al 2023). Los valores del índice de Pretzsch en los tres intervalos altitudinales no mostraron un comportamiento ascendente o decreciente relacionado con la altura, la distribución de especies en los tres estratos de altura de cada intervalo es de alta homogeneidad, ya que un valor del 100% indica que todos los taxones de la comunidad se distribuyen de manera equitativa (Caballero-Cruz et al 2022). El análisis de la estructura vertical presentó resultados superiores a lo reportado por diversos autores como Graciano-Ávila et al (2020) quienes estudiaron una comunidad con dos tratamientos silvícolas en 10 años (2007 al 2017) durante tres periodos de tiempo, señalan valores de A entre 2.66 a 2.72, Amax de 3.87 y Arel de 68 al 70%; al igual Alanís-Rodríguez et al (2020) citan un valor de A = 2.03 y Amax = 3.29 lo que representa una diversidad media en altura para un bosque de galería en una etapa madura sin alteraciones antropogénicas aparentes.…”
Understanding forest structure and diversity allows the development and analysis of strategies for the sustainable management of natural resources. The objective of the research was to contribute to the knowledge of tree structure, as well as its regeneration capacity in an altitudinal gradient in a Natural Protected Area in Madera, Chihuahua. The study included three altitudinal intervals: lower (2 307 to 2 466 m), middle (2 466 to 2 625 m) and upper (2 625 - 2 785 m), in which 30 circular sites of 500 m2 were distributed where the diameter and height of the upper trees were measured, as well as the density of regeneration. The vertical structure was obtained with the Pretzsch index (A), in addition, the importance value index (IVI), diversity with the Shannon-Wiener index (H') and richness with Margalef (Dmg) were evaluated, as well as the renewal capacity and damage present. The values of A show the greatest structural homogeneity in interval 2; the Pinaceae family registered the highest ecological weight in the IVI; the values of H' and Dmg were higher in stratum II, however, all are considered of low diversity and richness; the species Abies concolor and Pseudotsuga menziesii, showed the highest proportion of regeneration in the community, in which suppression is the frequent damage, however, 95% of the individuals were not affected. This information is useful for the conservation of these ecologically important communities in temperate forests.
Characterising the vegetation-pollen signal is a crucial task for enhancing the interpretation of fossil pollen records. This study analyses 28 surface soil samples collected in the surroundings of Iztaccíhuatl volcano, between 2,650 and 4,024 m asl. Pollen zones and ordination analysis were assessed to establish a qualitative connection between the pollen signal and the distribution of plant communities along the elevation gradient. The results show: (i) the predominant pollen type in the pollen assemblage is Pinus; (ii) pollen grains of Quercus and Alnus are present along the elevation gradient, even at high elevations where the parental plants are not typically found; (iii) samples taken between 2,650 and 3,338 m asl., where fir forests dominate, exhibit higher values of Abies pollen compared to samples above 3,405 m asl.; (iv) the locally-dispersed pollen of the hemiparasite Arceuthobium results key in identifying the presence of pine forests; and (v) pollen taxa such as Apiaceae, Eryngium, Valerianaceae, and Caryophyllaceae are linked to higher elevations, specifically where the plant communities of Pinus hartwegii and alpine grassland occur. The study suggests that the pollen signal along the elevation gradient is useful to characterise the main plant communities of the study site (fir forest, pine forest and alpine grassland). Additionally, the percentage variations of Abies in the pollen signal below 3,600 m asl. show the reduction of fir forest communities resulting from recent human activities in the area.
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