Low temperature during winter elicits differential responses among populations of the Mediterranean evergreen cork oak (Quercus suber)

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.

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Characterization of Cork Oak (Quercus Suber) Wood Anatomy

IAWA Journal ◽

10.1163/22941932-90000210 ◽

2009 ◽

Vol 30 (2) ◽

pp. 149-161 ◽

Cited By ~ 12

Author(s):

Vicelina B. Sousa ◽

Sofia Leal ◽

Teresa Quilhó ◽

Helena Pereira

Keyword(s):

Mediterranean Area ◽

Vessel Diameter ◽

Structural Features ◽

Quercus Suber ◽

Cork Oak ◽

Oak Wood ◽

Cork Production ◽

Water Conduction ◽

The Mediterranean ◽

Perforation Plates

The cork oak (Quercus suber L.) is important for ecological and socioeconomic sustainability and nature conservation in the Mediterranean area. Anatomical and structural features of cork oak wood were characterized at two sites in Portugal, including never-debarked trees and trees under cork production. Cork oak wood showed semi-ring porosity, solitary vessels with simple perforation plates, and large rays. Vessels were arranged in a diagonal to radial pattern, larger and more abundant in earlywood, and gradually decreasing in intermediate and latewood. In trees under cork production vessel distribution and frequency were altered, with more frequent and smaller pores, and a less distinct porosity pattern. Vessel diameter, element length and frequency were 133 ± 49 μm, 433 ± 103 μm and 2.9 ± 0.5 vessels/mm2 for never-debarked trees and 139 ± 50 μm, 341 ± 100 μm and 5.1 ± 1.5 vessels/mm2 for debarked trees. Multiseriate ray width ranged 0.15–1.04 mm, and uniseriate ray height 9.1–791.3 μm. Fibres had a mean length of 1.15 ± 0.20 mm. Vasicentric tracheids were frequent. Tyloses and crystals were commonly present. The anatomical features of cork oak wood favour water conduction and mechanisms of drought adaptation to the Mediterranean climate. The wood can also adapt to cork removal.

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Raffaelea quercina sp. nov. Associated with Cork Oak (Quercus suber L.) Decline in Portugal

Forests ◽

10.3390/f12040513 ◽

2021 ◽

Vol 12 (4) ◽

pp. 513

Author(s):

Maria L. Inácio ◽

José Marcelino ◽

Arlindo Lima ◽

Edmundo Sousa ◽

Filomena Nóbrega

Keyword(s):

Mediterranean Basin ◽

Quercus Suber ◽

Cork Oak ◽

Ambrosia Beetle ◽

Distribution Area ◽

Oak Decline ◽

Ambrosia Beetles ◽

Oak Trees ◽

The Mediterranean ◽

The Mediterranean Basin

Research Highlights: Raffaelea quercina sp. nov. is an ophiostomatoid fungus isolated from the ambrosia beetle Platypus cylindrus. The species occurs in symptomatic Portuguese cork oak trees, (Quercus suber L.), exhibiting vegetative decline. Background and Objectives: Quercus suber L. is a species restricted to the Mediterranean basin, of special economic importance as it constitutes the crucial raw material for the cork production industry, in particular for Portugal, the world’s leading producer. Over the last three decades a progressive and alarming decline of cork oak trees has been observed across its distribution area, including Portugal. The ambrosia beetle Platypus cylindrus, commonly known as the oak pinhole borer, establishes symbiotic relationships with fungi from which it depends for survival and for oak colonization. Some of these fungi are ophiostomatoid species of the Raffaelea genus, known as ambrosia fungi associated with ambrosia beetles. Some Raffaelea species exhibit phytopathogenic activity causing wilting and/or death of trees. The objective of the present study is to identify the association between P. cylindrus and Raffaelea species in Portuguese cork oak stands showing symptoms of disease and decline. Materials and Methods: A total of 300 adult insects were collected as they emerged from cork oak logs, sampled from symptomatic trees. Axenic isolates of Raffaelea species were obtained from the beetles and their galleries in the trunks and identified based on morphological features and molecular analysis of the SSU and LSU rDNA regions. Results: Two Raffaelea species were identified, i.e., R. montetyi and a novel Raffaelea species closely related to R. canadensis. The novel species is morphologically and genetically characterized in this study, and erected as Raffaelea quercina M.L. Inácio, E. Sousa & F. Nóbrega, sp. nov. Raffaelea quercina constitutes a new phytopathogenic fungal species associated with P. cylindrus and cork oak trees exhibiting symptoms of vegetative decline. Conclusions: Raffaelea species appear to have a significant role in cork oak decline. Future research on the association between P. cylindrus and Raffaelea species, encompassing the trans-European and North African wide-range of cork oak stands, would further clarify the relationships between ambrosia beetles, associated fungi and cork oak decline, contributing to a better understanding of the phenomena and for strategies aiming to halt the continuous decline of the unique cork oak stands enclosed in the Mediterranean basin.

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