Plasticity in dendroclimatic response across the distribution range of Aleppo pine (Pinus halepensis)

We investigated the variability of the climate-growth relationship of Aleppo pine across its distribution range in the Mediterranean Basin. We constructed a network of tree-ring index chronologies from 63 sites across the region. Correlation function analysis identified the relationships of tree-ring index to climate factors for each site. We also estimated the dominant climatic gradients of the region using principal component analysis of monthly, seasonal, and annual mean temperature and total precipitation from 1,068 climatic gridpoints. Variation in ring width index was primarily related to precipitation and secondarily to temperature. However, we found that the dendroclimatic relationship depended on the position of the site along the climatic gradient. In the southern part of the distribution range, where temperature was generally higher and precipitation lower than the regional average, reduced growth was also associated with warm and dry conditions. In the northern part, where the average temperature was lower and the precipitation more abundant than the regional average, reduced growth was associated with cool conditions. Thus, our study highlights the substantial plasticity of Aleppo pine in response to different climatic conditions. These results do not resolve the source of response variability as being due to either genetic variation in provenance, to phenotypic plasticity, or a combination of factors. However, as current growth responses to inter-annual climate variability vary spatially across existing climate gradients, future climate-growth relationships will also likely be determined by differential adaptation and/or acclimation responses to spatial climatic variation. The contribution of local adaptation and/or phenotypic plasticity across populations to the persistence of species under global warming could be decisive for prediction of climate change impacts across populations. In this sense, a more complex forest dynamics modeling approach that includes the contribution of genetic variation and phenotypic plasticity can improve the reliability of the ecological inferences derived from the climate-growth relationships.This work was partially supported by Spanish Ministry of Education and Science co-funded by FEDER program (CGL2012-31668), the European Union and the National Ministry of Education and Religion of Greece (EPEAEK- Environment – Archimedes), the Slovenian Research Agency (program P4-0015), and the USDA Forest Service. The cooperation among international partners was supported by the COST Action FP1106, STREeSS

Regeneration of Lebanon cedar (Cedrus libani A. Rich.) on karstic lands in Turkey

Lebanon cedar (Cedrus libani A. Rich.) is significant from the historical, cultural, aesthetic, scientific and economic perspectives. It is presently found primarily in the Taurus Mountains of Turkey with extensive and magnificent forests. Historical records also indicate extensive and splendid forests of it in Syria and Lebanon. However, heavy cutting, burning and goat grazing for the past 5000 years have left only small populations in these countries. Although the same disturbances have continued in Anatolia (Asia Minor), the almost inaccessible topography of the Taurus Mountains has prevented Lebanon cedar from being extirpated

Silvicultural characteristics and natural regeneration of Pinus brutia Ten. - a review

Pinus brutia Ten. is a characteristic species of the eastern Mediterranean. P. brutia and P. halepensis Mill. are distinct species: but P eldarica, P stankewiczii and P pityusa are subspecies of P. brutia. Fire is the major disturbance in P brutia forests, and several adaptations generally contribute to post-fire regeneration of P. brutia: however, P. brutia can also naturally regenerate without fire. Flowering occurs between March and May. Seed distribution Occurs throughout the year, with maximum dispersal in August and the great majority of seeds dispersing within the period July-December. P. brutia retains some closed cones and so establishes a natural canopy seed bank. Seed germination occurs in the rainy season with two frequency peaks: the major one in spring and a minor one in autumn. P. brutia seedlings develop rapidly-growing tap roots. Shelterwood, clearcutting and strip clearcut methods can successfully be applied to P. brutia forests, depending on local conditions. Density of P. brutia seedlings was greater and seedlings were more vigorous when the natural regeneration methods were combined with prescribed fire. Clearcutting methods combined with laying cone bearing branches on the surface of the soil and additional seeding increases regeneration success. Ground litter of 2-4 cm creates a medium that reduces evapotranspiration, delays growth of competing vegetation, and increases seedling survival. Successful regeneration must be established by the end of first vegetation period