Analysis of diameter distributions and conservation of forests of northern Morocco (original) (raw)
Related papers
Distribución de clases diamétricas y conservación de bosques en el norte de Marruecos
2008
El paisaje forestal mediterráneo que vemos en la actualidad es el resultado de la actuación del hombre y su gestión de los recursos a lo largo de la Historia (Le Houérou, 1981; McNeill, 1992; Marañón y Ojeda, 1998). Entre los procesos que han contribuido a la deforestación de la Cuenca Mediterránea, Thirgood (1981) ha destacado los siguientes: la transformación del bosque en cultivos y pastos, la explotación de ma-dera para la construcción de barcos, la extracción de combustible para uso doméstico o para la minería, las guerras e invasiones, los incendios y el sobrepastoreo. Los bosques del Rif, y en particular de la Península Tingitana (norte de Marruecos), han sufrido episodios intensos de perturbación que han sido más acentuados en la época reciente (Mikesell, 1960; Reille, 1977; Taiqui, 1997). La mayor parte de los bosques actuales de Marruecos son testigos de una explotación intensa, que se refleja en su estructura y composición. Excepcionalmente, los morabitos o «bosques sagrados» han sido respetados en señal de respeto hacia el santo musul
The height-diameter ratios for trees from six woody species used in forest plantations in Southern Costa Rica were studied. These ratios can be described using non-linear functions; however, it was found that the height-diameter curve was affected by the site quality and the stand density. Twenty six models, described in the literature and based on two variables were tested; three other models that take into account stand parameters such as dominant height and mean diameter were also tested. Taking statistical and practical aspects into account, a model which could predict the height of a tree as a function of chest-high diameter was selected. The use of the model is an important factor when estimating the productivity and growth characterization of a stand, in situations where measuring the height of every tree within sampling plots is difficult.
Copper distribution in Mediterranean forest ecosystems
Rev. chil. hist. nat, 2002
We have analyzed the distribution of copper concentrations, and the effects of anthropogenic inputs, in the components of two forest ecosystems using a comparative approach. Ecosystem components were defined using a processfunctional conceptual model. Biotic components corresponded to the morphological structures of trees, the abiotic components to the soil horizons. We chose two areas that differed on the absence (reference ecosystem) and presence (perturbed ecosystem) of an anthopogenic copper source (the Ventanas-Maitencillo Refinery). Results show that the anthropogenic copper is mostly retained in the partially decomposed matter, and that the biotic components of the perturbed ecosystem show higher that normal copper concentrations. We discuss the controlling variables of the intrasystemic copper cycle in forest ecosystems.
Els briòfits de la Réserve Naturelle de la Forêt de la Massane (SE de França)
Orsis, organismes i sistemes: revista de botànica, zoologia i ecologia, 2001
Hem identificat 153 tàxons dels quals 121 són molses i 32, hepàtiques. Mnium hornum entapissa una bona part del sòl de la fageda. Jungermannia subulata és abundant a les parts humides a les vores dels rierols. Els nombrosos epífits sobre faigs o roures formen una bona cobertura i tenen una excel•lent vitalitat. Predominen les espècies de distribució temperada, mentre que les boreals, suboceàniques i oceànicomediterrànies són menys abundants. D'una altra banda, malgrat la proximitat al mar de la zona de la Reserva, les de distribució mediterrània i submediterrània són escasses.
2014
The aim of this study was to compare the accuracy of Weibull, reverse Weibull, S B Johnson, Gamma and Beta distributions, fitted with the method of moments and maximum likelihood, for describing diameter distributions in stands of Pinus taeda, Eucalyptus globulus, and Eucalyptus dunnii in Uruguay. Data from 429 permanent plots of P. taeda, 185 plots of E. globulus and 271 plots of E. dunnii were used. To compare the quality of fit for the probability distribution function (pdf), the Kolmogorov-Smirnov and Reynolds error indices were used. The function S B Johnson presented a better fit on the plots of P. taeda, while the inverted Weibull function was more accurate for Eucalyptus species. The method of moments was more accurate than maximum likelihood.
Density management guide for natural Pinus teocote Schlecht. et Cham. fotest in Hidalgo
Revista Mexicana De Ciencias Forestales, 2013
Density is a reliable indicator of the degree of occupation of a specific time and place by trees; besides, it is one of the few variables that represent the structure of forests in a simple, objective manner. A density management guide for Pinus teocote was created for 12 municipalities of eastern Hidalgo. In order to develop the methodology of Reineke's Stand Density Index, 282 sampling sites with a surface between 100 and 1 000 m 2 in full density stands were evaluated; also, in order to define the Crown Competition Factor, 131 isolated individual trees were measured. During the making of the density management guide, the maximum density line or level "A" was determined according to the model proposed by Reineke: an index of 755 trees to a 25 cm square diameter. Line "B", or minimum density, was established based on the isolated trees, according to the Crown Competiton Factor: the recorded index was 421 trees to the same square diameter. Based on the guide thus generated, a relationship was established between quantitative indices allowing comparison between the density degree and certain dasometric variables in Pinus teocote stands, regardless of their age, the quality of the site and the dimensions of the trees within specific density intervals.
Model_Gestion_Bosques_Mediterraneos.pdf
El modelo que se presenta a continuación es una propuesta técnica de gestión, desarrollada específicamente para incorporar el rendimiento sostenido en el manejo de los recursos asociados a los ecosistemas mediterráneos de Chile. Esta herramienta se sustenta sobre la base de los principios, criterios y parámetros del ordenamiento forestal, y considera en particular, el estado actual de degradación de los ecosistemas mediterráneos como principal elemento de análisis. En este contexto, el modelo persigue como principal meta, que la utilización de estos bosques considere su conservación, recuperación y mejore su estado de fuente generadora de productos y servicios ambientales, para el presente y futuro.