Modelo dinámico de crecimiento en altura para monte alcornocal (Quercus suber L.) españoles y tunecinos

Seven simple and advanced dynamic polymorphic functions were considered to develop a dominant height growth model for Spanish and Tunisian cork oak forests. Data from 115 stem analyses performed in two regions in each country were used to fit the equations. Parameter estimates were obtained using the Dummy variable method. Both numerical, graphical and biological consistency were used to compare alternative models. The dynamic equation finally selected was derived from the Hossfeld model by considering the shape parameter to be related to site productivity. An analysis of the dominant height growth patterns between the two countries indicated that the same dominant height growth model was valid for both countries. This dominant height growth model allows estimation of dominant height with a level of reliability of at least 83% from an age of 15 years for a prediction interval of less than 40 years.Para desarrollar un modelo de crecimiento en altura dominante para monte alcornocal en España y Túnez se han probado siete funciones polimórficas simples y dinámicas. Para ello se han utilizado datos procedentes de 115 análisis de troncos realizados en dos regiones distintas de cada país. Para estimar los parámetros se utilizó el método de las variables ficticias. Los modelos fueron comparados de forma numérica y gráfica. La ecuación dinámica finalmente seleccionada fue derivada a partir de la ecuación de crecimiento de Hossfeld considerando el parámetro de forma como relacionado con la productividad de la estación. El análisis del patrón que sigue el crecimiento en altura dominante en ambos países indica que el mismo modelo de crecimiento en altura dominante es valido para ambos países. Este modelo de crecimiento en altura dominante nos permite estimar la altura dominante con una fiabilidad de más de un 83% a partir de los 15 años para un periodo de predicción menor de 40 años

Effect of geographic origin in mineral composition of zeen oak acorns (Quercus canariensis Willd)

The aim of the current study was to investigate the effect of geographic origin in mineral compositions on the Q. canariensis acorns. The results showed that there were significant (p < 0.5) differences between populations for macronutrients Sodium (Na), Calcium (Ca), Potassium (K)) except for Phosphorus (P) and for all studied micronutrients: Iron (Fe), Manganese (Mn) and zinc (Zn). Potassuim contents of acorn ranged from 5,638 to 7,667 mg/g MS with highest being for Nefza acorn and lowest for Bni Mtir ones. It is the highest macronutrients for all population. However Iron was the most abandon micronutrient, varied widely from 0,491 mg/g MS (Bni Mtir) to 1,230 mg/g MS (Nefza). No significant differences were recorded for Heavy metal. The concentrations of Chromium (Cr), Nickel (Ni) and Cobalt (Co) in acorns flour are null. On the other hand Cadmium (Cd) and Copper (Cu) were found but with concentrations which were much lower than that the acceptable limits for herbs and spices by WHO

Toward Decision-Making Support: Valuation and Mapping of New Management Scenarios for Tunisian Cork Oak Forests

Forest ecosystems are an important anthropogenic pillar to human wellbeing, providing a multitude of ecosystem services. In Mediterranean countries, where climate change effects are exponentially increasing, the value of the forest ecosystem services is even higher and their preservation is more crucial. However, the biophysical and economic value of such services is usually not observable due to their non-marketable characteristics, leading to their underestimation by decision-makers. This paper aims to guide decision-making through a set of new management scenarios based on ecosystem services&rsquo; values and their spatial distribution. It is a cumulative multidisciplinary study based on biophysical models results, economically valued and implemented using the geographic information system (GIS) to analyze spatial data. The investigation was based on a biophysical and economic valuation of cork, grazing, carbon sequestration and sediment retention as a selection of ecosystem services provided by cork oak forest (Ain Snoussi, Tunisia). The valuation was made for the actual situation and two management scenarios (density decrease and afforestation of the shrub land), with emphasis on their spatial distribution as a basis to new management. The total economic value (TEV) of the investigated services provided by Ain Snoussi forest (3787 ha) was &euro;0.55 million/year corresponding to &euro;194/ha/year. The assessment of two different scenarios based on the land cover changes showed that the afforestation scenario provided the highest TEV with &euro;0.68 million/year and an average of &euro;217/ha, while the density decrease scenario provided &euro;0.54 million/year and an average of &euro;191/ha. Such results may orient decision-makers about the impact new management may have, however they should be applied with caution and wariness due to the importance of the spatial dimension in this study

Plant diversity in different bioclimatic zones in Tunisia

The Republic of Tunisia, located in northern Africa, faces various environmental challenges caused by anthropogenic practices such as overgrazing, deforestation, and desertification. The conversion of natural ecosystems is the major cause of plant biodiversity loss. Tunisia can be divided into three main climatic zones as follows: a northern Mediterranean climate zone, a central steppe climate zone, and a southern desert climate zone. Because of this great environmental diversity, there are distinctive vegetation and various genetic resources in Tunisia. This research was conducted to investigate plant biodiversity within the various bioclimatic zones and to characterize useful plant resources in Tunisia. We investigated native, medicinal and aromatic, desert, and soil erosion control plant species