Observed and Predicted Geographic Distribution of Acer monspessulanum L. Using the MaxEnt Model in the Context of Climate Change

Acer monspessulanum (Montpellier Maple) is an important deciduous tree species native to the Mediterranean region. It is largely distributed in the southern part of western Europe; however, it is geographically less present in north Africa and western Asia. The effects of the most significant environmental variables for its habitat suitability, and climate change, are unclear in terms of the future changes to its distribution. The objective of the present study was to model the current and future geographical potential distribution of the Montpellier Maple in the Mediterranean basin and West Asia using maximum entropy modeling software (MaxEnt). The value of the Area Under the Curve (AUC) of MaxEnt was used to analyze the model’s performance. More than 5800 well-distributed presence points, elevation, slope, aspect, topographic wetness index (TWI), natural vegetation characteristics from MODIS products, and 19 bioclimatic variables were used to conduct the study. Regarding the projections of the species distribution under climate change, 17 global climatic models were used under two RCP scenarios (4.5 and 8.5) for the 2040–2060 and the 2060–2080 time periods. The results show that temperature seasonality (40% contribution to the model), elevation (33.5%), mean annual temperature (6.9%), mean annual precipitation (6.2%), and max temperature of the warmest month (4.5%) were identified as the primary factors that accounted for the current distribution of the Montpellier Maple. Under the climate change scenarios, MaxEnt predicts a large decrease in the species suitability area, with a shift towards the southwestern regions of the species distribution, especially to the mountainous zones of the Moroccan Atlas. Our results show that climate largely limits the distribution of the Montpellier Maple in the Mediterranean basin, as its change in the future is expected to significantly reduce the suitable area by more than 99% from the historical climate conditions, to reach only 16,166.9 and 9874.7 km2 under the moderate RCP4.5 and extreme RCP8.5 scenarios, respectively, by the end of the 21st century. Our study can provide a good view of the future changes in the distribution of Montpellier Maple for its protection and sustainable management.Funding support for this research was provided by the project titled “Eating the wild: Improving the value-chain of Mediterranean Wild Food Products (WFP)”—WildFood (Reference Number: 2019-SECTION2-29) and the project: HYDROMED (PID-2019-111332RB-C21). Hassane Moutahir is supported by the Generalitat Valenciana and the European Social Fund (APOSTD20/2019-7956)

Estimate of biomass and carbon pools in disturbed and undisturbed oak forests in Tunisia

Aim of the study. To estimate biomass and carbon accumulation in a young and disturbed forest (regenerated after a tornado) and an aged cork oak forest (undisturbed forest) as well as its distribution among the different pools (tree, litter and soil).Area of study. The north west of TunisiaMaterial and methods. Carbon stocks were evaluated in the above and belowground cork oak trees, the litter and the 150 cm of the soil. Tree biomass was estimated in both young and aged forests using allometric biomass equations developed for wood stem, cork stem, wood branch, cork branch, leaves, roots and total tree biomass based on combinations of diameter at breast height, total height and crown length as independent variables.Main results. Total tree biomass in forests was 240.58 Mg ha-1 in the young forest and 411.30 Mg ha-1 in the aged forest with a low root/shoot ratio (0.41 for young forest and 0.31 for aged forest). Total stored carbon was 419.46 Mg C ha-1 in the young forest and 658.09 Mg C ha-1 in the aged forest. Carbon stock (Mg C ha-1) was estimated to be113.61(27.08%) and 194.08 (29.49%) in trees, 3.55 (0.85%) and 5.73 (0.87%) in litter and 302.30 (72.07%) and 458.27 (69.64%) in soil in the young and aged forests, respectively.Research highlights. Aged undisturbed forest had the largest tree biomass but a lower potential for accumulation of carbon in the future; in contrast, young disturbed forest had both higher growth and carbon storage potential.Keywords: Tree biomass; disturbance; allometry; cork oak forests; soil organic carbon stock

Fatty acids and triacylglycerols composition from Tunisian Acacia species seed oil

AbstractRecently, plant seeds that have not been enough explored and exploited are cheap sources of a lot of natural molecules for industrial applications. The aim of the present study was to evaluate for the first time the composition of fatty acids and triacylglycerols (TAG) of mature unexploited seeds of some Acacia species (Acacia cyclops, Acacia ligulata and Acacia salicina) harvested in Tunisia in order to reveal their potential for human consumption.Results showed that, Acacia seed oils were mainly unsaturated (more than 71%). The polyunsaturated fatty acids were the major fractions (52–68%) with the linoleic acid as the major fatty acid (more than 52%), followed by oleic acid (15–27%) as monounsaturated fatty acid. The TAG composition was significantly different among the three Acacia species. PLL, PLO, LnLO, OLL, OOL, and OOO were the major forms. Acacia seed oil could be used as potential source of oil with high industrial value; nevertheless in vivo tests are essential to confirm its safety before use

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

Monitoring land-cover changes in Mediterranean coastal dunes, northwest Tunisia, using remote sensing data

Coastal dune landscapes are subject to morphological and ecological changes. In many parts of the world, coastal dunes are under severe pressure. The present study illustrates an integrated remote sensing and Geographical Information System (GIS) approach, i.e., geospatial techniques for assessing land-cover dynamics in Zouaraa coastal dunes, located in northwest Tunisia. As a main result, the analysis of the situation in the past six decades indicates that the dune area showed a decreasing trend with up to 31% (i.e., 6198 ha) in favour of forest area, which has increased by up to 6485 ha. The geo-spatial analysis revealed that restoration works have positively contributed to stabilize coastal dune systems with a substantial increase in vegetation cover. An increase in drought frequency and intensity was detected during the 1952-2017 period using the SPEI index, which enhanced the vegetation activity and growth in the study area. The SPEI significantly correlated with vegetation greenness on the 12- and 24-months’ time scales. The croplands, water and buildings in the study area have increased respectively by 6% (i.e., 1256 ha), 13% (i.e., 3073 ha) and 3% (i.e., 719 ha). In contrast, land cover like shrub and bare soil has decreased respectively by 13% (i.e., 3073 ha) and 2% (i.e., 1831 ha) during the same period. Furthermore, this study highlights the importance of the revegetation techniques undertaken for conserving coastal dune systems. The findings of this study allow land-use planning decision makers to manage and improve situations in similar coastal regions.This work was supported by the National Research Institute for Rural Engineering, Waters, and Forestry-INRGREF. Laboratory of Management and Valorization of Forest Resources, Tunisia. This research is part of the project: HYDROMED (PID-2019-111332RB-C21)

Evolution-based approach needed for the conservation and silviculture of peripheral forest tree populations

The fate of peripheral forest tree populations is of particular interest in the context of climate change. These populations may concurrently be those where the most significant evolutionary changes will occur; those most facing increasing extinction risk; the source of migrants for the colonization of new areas at leading edges; or the source of genetic novelty for reinforcing standing genetic variation in various parts of the range. Deciding which strategy to implement for conserving and sustainably using the genetic resources of peripheral forest tree populations is a challenge. Here, we review the genetic and ecological processes acting on different types of peripheral populations and indicate why these processes may be of general interest for adapting forests and forest management to climate change. We particularly focus on peripheral populations at the rear edge of species distributions where environmental challenges are or will become most acute. We argue that peripheral forest tree populations are “natural laboratories” for resolving priority research questions such as how the complex interaction between demographic processes and natural selection shape local adaptation; and whether genetic adaptation will be sufficient to allow the long-term persistence of species within their current distribution. Peripheral populations are key assets for adaptive forestry which need specific measures for their preservation. The traditionally opposing views which may exist between conservation planning and sustainable forestry need to be reconciled and harmonized for managing peripheral populations. Based on existing knowledge, we suggest approaches and principles which may be used for the management and conservation of these distinctive and valuable populations, to maintain active genetic and ecological processes that have sustained them over time

Morphological variability of cones and seeds of aleppo pine and stone pine in Tunisia

Une étude sur la variabilité morphologique des cônes et des graines de Pinus halepensis Mill. et Pinus pinea L. en fonction des conditions géographiques des stations a été entreprise. L'analyse de la variance des paramètres morphologiques étudiés, pour les deux espèces, montre des différences inter-stations hautement significatives. Ces différences traduisent dans une large mesure l'influence des conditions stationnelles sur la morphologie des cônes et des graines et sur la production fructifère des arbres. Les peuplements de Pin d'Alep les plus performants sont ceux d'altitude à climat aride supérieur. L'un des peuplements de Pin pignon se distingue nettement des autres par son rang pour les divers paramètres étudiés

Results of comparative trials between stone Pine (Pinus pinea L.)

Stone pine (Pinus pinea L.) is widely used for reforestation in northern Tunisia to produce both fruit and timber. A genetic improvement programme for this species has begun, the first stage of which is a geographic exploration of its genetic variability. Experimental plots have been established in several countries bordering the Mediterranean Sea. This article reports the results of 10 years of monitoring the two plots in northern Tunisia, at Jbel Essmaa and Oued El Bir. The survival and vigour data recorded for seedlings of various provenances are presented and analysed. Survival and growth of the provenances differ significantly between the two sites whereas differences are not significant within each site taken individually.Le Pin pignon (Pinus pinea L.) est largement utilisé dans les reboisements du Nord de la Tunisie pour ses productions ligneuse et fructifère. Un programme d’amélioration génétique de cette espèce a été mis en oeuvre avec une première étape d’exploration géographique de sa variabilité génétique. Des dispositifs expérimentaux impliquant plusieurs pays du pourtour méditerranéen ont été installés dans différents pays. Nous présentons, ici, le bilan des deux dispositifs de Jbel Essmaa et Oued El Bir situés dans le Nord de la Tunisie après 10 années de suivi. Les résultats enregistrés au niveau de la survie et de la vigueur des plants de différentes provenances et entre les sites sont présentés et analysés. Il en ressort qu’il existe une différence significative entre les deux sites, mais les différences entre la survie et la croissance des provenances ne sont pas significatives à l’intérieur de chaque site