Biogeosciences and Forestry Biogeosciences and Forestry Climate change impacts on spatial distribution, tree-ring growth, and water use of stone pine (Pinus pinea L.) forests in the Mediterranean region and silvicultural practices to limit those impacts Kaouther Mechergui (1-2) , Amal Saleh Altamimi (3) , Wahbi Jaouadi (1-2) , Souheila Naghmouchi (2) Stone pine (Pinus pinea L.) has been cultivated since centuries in Mediterranean areas for its products and economic benefits, including edible pine nuts, timber, mushrooms, firewood, and grazing. However, current management objectives of stone pine stands also include recreational use, biodiversity conservation, protection from soil erosion, and CO2 fixation. Stone pine stands are considered to be among the ecosystems most vulnerable to climate change, and the current increase in drought frequency in the Mediterranean Basin has been shown to negatively impact their long-term establishment. Understanding the effects of climate change on the distribution, tree-ring growth and water use of stone pine forests can help assessing the adaptive capacity of the species, and developing management programs aimed at its conservation. This paper reviews the impacts of climate change on stone pine in the Mediterranean region. The high sensitivity of stone pine to climate change has been widely demonstrated in that: (i) climatic models predict the loss of suitable habitats and the shift of its geographical distribution in the next future; (ii) tree-ring analysis showed that winter and spring rainfalls have positive effects on growth, whereas high spring temperature has a negative effect; (iii) the strategy of stone pine to cope with water deficit affects the processes regulating its growth, including wood formation, leading to peculiar tree-ring anatomical features such as intra-annual density fluctuations. The silvicultural interventions and the most effective management strategies for stone pine forests are reviewed and discussed in the context of current climate change in the Mediterranean Basin.

Background:The objectives of this study are to (i) determine the variations in the soil composition among six different habitats of six Rhus tripartita populations, (ii) identify and compare the variation in the fruit and seeds parameters of these populations, and (iii) evaluate the differences in Rhus tripartita allelopathic activities among populations on the Chenopodium album weed on it as biological control method. Results:The soils analysis of the six habitats of Rhus tripartita populations revealed a significant variation in the soil variables, while salinity, organic matter, and macro-elements (Cl -, HCO 3-, Na + , K + , Ca + and Mg 2+ ) were the most controlling factor. Rhus tripartita fruits and seeds showed that there is an inter-site variability observed between populations. Morphological study indicating a large-scale diversity among the provenances. It is related to the phenotypic characteristics which may be due to the genetic effect. The Rhus tripartita extract concentration, especially population 4 (P4), showed potential allelopathic activity against Chenopodium album, where the germination was strongly inhibited at a concentration of 10 g l -1 . Under same concnetration, seedling root length and shoot lenght were seriously affected. Conclusion:These extracts could be used as green source, eco-friendly bioherbicide and to be integrated into the weed control program of weeds. However, further study is needed for characterization of essential oil of Rhus tripartita and their potential allelopathic activities against the Chenopodium album weed or maybe other weeds, and evaluate its valuable economic use on a large scale.

In this study, we modelled the current and future distribution of the V. tortilis subsp. raddiana var. raddiana for the period from 2050 (RCP 2.6; RCP 4.5; RCP 8.5) to 2070 (RCP 2.6; RCP 4.5; RCP 8.5) using a maximum entropy (MaxEnt) species distribution model. Our results showed that the precipitation-associated variables had the strongest effect on the distributions of this species. Among these variables, the precipitation of driest quarter (Bio17: 31.9 of percentage contribution) was the most important variable affecting the suitability of the habitats. Under the current climate conditions, the areas of the highly suitable (>0.6) habitat for V. tortilis in the arid land of Tunisia were 1142.532 km 2 . In the year 2050 (RCP 2.6) and 2070 (RCP 2.6), the highly suitable habitat areas for V. tortilis will continue to increase and eventually reach to 3300.704 and 5181.630 km 2 , respectively. In the year 2050 (RCP 8.5) and 2070 (RCP 8.5), the highly suitable habitat areas for V. tortilis will continue to increase and eventually reach to 9614.449 and 14684.870 km 2 , respectively. With the climate change, the highly suitable habitats of V. tortilis would shift to the southeast and northeast of Bled Talah.

Climate change represents an important challenge for forest management and the silviculture of stands and it is known that climate change will have complex effects on cork oak forest ecosystems. North Africa and the Mediterranean basin are especially vulnerable to climate change. Under the effect of climate change, cork oak will disappear from a large area in the future, and the rest will migrate to higher altitudes and latitudes. This study aimed to evaluate the effect of climate change on the spatial distribution of Quercus suber L. and cork production in the Mediterranean area, and the risk of its exclusion by the Aleppo pine (Pinus halepensis Mill.) expansion. The literature review showed that up to 40% of current environmentally suitable areas for cork oak may be lost by 2070, mainly in northern Africa and the southern Iberian Peninsula. Temperature directly influences atmospheric evaporative demand and should affect cork productivity. Precipitation is the main factor that positively influences cork growth and several authors have confirmed the negative effect of drought on this growth. Currently, cork oak habitats are colonized in several places mainly by the Aleppo pine. Under climate change, Aleppo pine is projected to occupy higher altitude sites and several authors have predicted that current and future global warming will have a positive influence on Aleppo pine growth in wet sites. In the future and under climate change, there is a strong possibility that the Aleppo pine will colonize cork oak habitat. Finally, we proposed management practices to protect cork oak against climate change and Aleppo pine expansion.

Background: Stone pine (Pinus pinea L.) is one of the characteristic species of the Mediterranean flora. This species has been used since ancient times because of its economic importance. This study was carried out because stone pine forests in the Mediterranean area, as carbon sinks, are one of the mitigation strategies considered to face climate change. Also, stone pine forests are of great socio-economic importance on an international scale due to the high demand for pine nuts and the important role of this emblematic species in agroforestry. The objectives of this study are, firstly, the evaluation of biomass and carbon storage capability and, secondly, the study of agroforestry interest of Pinus pinea L. and management practices to increase carbon stocks. Results:A review of research and knowledge was carried out on the subject based on a selection of publications that have been made in the Mediterranean area. The main conclusions are that stone pine forests have a very high biomass stock and a high storage potential in the future. However, these forests could be a potential carbon reservoir in the coming years and thus on climate change mitigation. In addition, the practice of agroforestry in the stone pine ecosystem can create jobs and many sources of income for the local population and improve their living standards. Conclusion:Finally, this review of research results can serve as an initial basis for refining management practices to improve the establishment of pine trees and tools to help forest managers in quantifying biomass, thereby contributing to the accurate estimation of carbon sequestration and stocks in stone pine stands and agroforestry practices.