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Effect of human disturbance on the structure and regeneration of forests in the Nevado de Toluca National Park, Mexico

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Journal of Forestry Research 2012年第1期23卷 39-44页

作者： angel rolando endara agramont Sergio Franco Maass Gabino Nava Bernal Juan Ignacio Valdez Hernández Todd S.Fredericksen Instituto de Ciencias Agropecuarias y Rurales(ICAR) Universidad Autónoma del Estado de MéxicoInstituto Literario N°100Col.Centro.PO.Box 50000.TolucaMéxico Colegio de Posgraduados Carretera México-TexcocoKm.36.5Montecillo.PO.Box 56230TexcocoMéxico School of Natural Sciences and Mathematics Ferrum CollegeP.O.Box 1000Ferrum VA 24088USA

Sample plots were established in the principal forest types in the the Nevado de Toluca National Park, Mexico including those domi- nated by Pinus hartwegii, Abies religiosa, Quercus laurina and Alnus jorullensis. The vertical structure was defined by three strata in the coniferous forests and two strata in the broadleaved forests. Timber harvesting in Abies religiosa and Quercus laurina forests and fires generated by humans in Pinus hartwegii forests impeded the recruitment of saplings. Mature trees were also heavily impacted by logging in Pinus hartwegii forests. On the contrary, Alnusjorullensis forests were increas- ing due to the disturbance of Pinus and Quercus forests, as well aban- doned crop lands within the park. A combination of logging, uncon- trolled fire, and grazing appears to be compromising the recruitment of important tree species in this national park. These factors, together with human settlements, have also increased the proportion of early succes- sional species. Changes in forest structure from human disturbance indicate a need to control these activities if conservation goals are not to be compromised.

关键词： forest structure human disturbance mountain forests

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Analysis of Fragmentation Processes in High-Mountain Forests of the Centre of Mexico

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American Journal of Plant Sciences 2013年第3期4卷 697-704页

作者： angel rolando endara-agramont Rafael Calderón-Contreras Gabino Nava-Bernal Sergio Franco-Maass Instituto de Ciencias Agropecuarias y Rurales Toluca México Universidad Autónoma Metropolitana D. F. México México

High-mountain forests (>3500 masl) are the main supplier of environmental services to Mexico City and its metropolitan area. Taking as a study case the Nevado de Toluca National Park, this article focuses on the considerable reduction on the density of its forest cover, characterised by disturbances in the structure and dynamics of Pinus hartwegii. This specie is located towards the upper limits of the altitudinal gradient (3500 - 4100 masl) constituting the only pine species in the world capable to be established in those extreme environmental conditions. The information was collected through the implementation of 30 Sampling Plots (SP) of 20 × 50 mts (1000 m2) in three forest density categories: dense, semi-dense and fragmented. For each forest category, all trees ≥2.5 cm DBH were measured in 10 SPs. The measurement variables were DBH, total and commercial height, forest health and forest extraction. The results show the abundance of dense, semi-dense and fragmented forest (336, 202 and 150 trees/Ha-1), with extraction percentages of 11%, 20% and 33% respectively. The horizontal structure distribution shows the shape of an inverted J for the three conditions. However, the phytosanitary conditions of the semi-dense forests (83% infested trees) and fragmented (63% infested trees), do not guaranties the survival of the adult trees, implying an intensification of the fragmentation process for the next decade;given the reduction of the regeneration patterns due to the lack of healthy tree breeding.

关键词： High-Mountain Forests Fragmentation Forest Structure Forest Health

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Identification of Arceuthobium globosum using unmanned aerial vehicle images in a high mountain forest of central Mexico

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Journal of Forestry Research 2020年第5期31卷 1759-1771页

作者： Luis A.Leon-Banuelos angel R.endara-agramont William Gomez-Demetrio Carlos G.Martınez-Garcıa E.Gabino Nava-Bernal 50000 TolucaMexicoMexico

The identification of forests infested by parasitic plants is important for the design of appropriate control and prevention *** images and geographic information systems are commonly used to analyze the presence of pest and parasitic plants in the *** there is a need for finer *** the last decade,the use of unmanned aerial vehicles has become increasingly common for capturing aerial images(<10 cm per pixel).The objective of the study was to obtain RGB values(Red,Green and Blue)through the colorimetric ranges for use in identification of Yellow Dwarf Mistletoe(YDM)(Arceuthobium globosum)in aerial images taken in a forest of central Mexico via a programmed *** tonalities of YDM were classified according to its phenological stages,***(young stage),yellow(adult stage),and brown(senescence stage),considering two light intensities,sunny and ***-parametric tests were used in statistical *** Spearman test showed significant negative correlation(p<0.001)between phenological stage and colour,indicating that lower RGB values were associated with greater *** differences between groups were analysed using Kruskal–Wallis(p<0.01)and Mann–Whitney tests(p<0.01).The applied algorithm identified the presence and predominant colours of YDM according to its phenological stage.

关键词： Colorimetric analysis RGB Pinus hartweggi Parasitic plants Remote sensing

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