Development of cork oak (Quercus suber L.) seedlings in response to tree shelters and mulching in northwestern Tunisia

The need for reforestation in cork oak （Quercus suber L.） areas is challenged by difficulties. Principal among these is herbivory of young plants, vegetative competition, and slow growth rates of cork oak seedlings. We evaluated the early development of cork oak seedlings treated using tree shelters and mulching in northwestern Tunisia. We tested three tree shelter treatments （non-vented, vented, and control） to shield seedlings from animal damage and five mulch types to control competing vegetation （Italian Stone Pine, Lentisk, combination of Italian Stone Pine and Lentisk （organic mulches）, gravel （inorganic mulch） and no mulch）. At the end of the two-year experiment, sheltered seedlings were 89-99% taller than unshelteredseedlings and had higher numbers and lengths of shoot growth flushes. In contrast, both stem diameter growth and dry weight biomass （from samples extracted after two years） were significantly reduced inside tree shelters. Root-to-shoot ratio was not significantly different in sheltered vs. unsheltered seedlings, suggesting that tree shelters do not adversely affect this parameter. Mulching alone did not favour growth, but could be beneficial when combined with tree shelters. The combination of vented tree shelters and gravel mulch was the most effective treatment for promoting diameter, height and stem volume growth.

Callogenesis of Cork Oak(Quercus suber L.)through In Vitro Culture of Nodes and Internodes

The present study is about in vitro culture of cork oak, through callogenesis from nodes and internodes, withdrawn from seedlings of three months. These latter were obtained after acorns germination on peat. Nodes showed a high capacity for callogenesis and the best rate was obtained on a medium containing Woody Plant Medium (WPM) macronutrients, Murashige and Skoog (MS) micronutrients and vitamins, 4.5 μM of 6-Benzylaminopurine (BAP), 7 μM of 2-naphthalineacetic acid (NAA) and 30 g/L of Sucrose. Calluses are transplanted onto the same mineral solution, with or without growth regulators, and in the 3rd transplanting;small white embryos appear on the surface of calluses.

Growth phenology adjusts to seasonal changes in water availability in coexisting evergreen and deciduous mediterranean oaks

Different leaf(evergreen vs.deciduous habit)and xylem(diffuse-vs.ring-porous wood)traits represent contrasting strategies to face seasonal changes in water availability and temperature.However,how contrasting leaf and xylem habits of coexisting tree species affect stem wood formation and tree-ring development remains poorly understood.Here,we investigated the spatio-temporal patterns of wood formation in two deciduous oaks(Quercus faginea and Quercus petraea)and two evergreen oaks(Quercus ilex and Quercus suber)coexisting in seasonally dry Mediterranean forests along an aridity gradient in Spain.We hypothesized that growth responses to drought and intra-and inter-annual growth patterns would differ between functional groups.We simulated intra-and interannual growth using a modified version of the Vaganov-Shashkin(VS)process-based,growth model.The VS model simulations were used to estimate growth changes under a high emission scenario(RCP 8.5)for the current distribution of the study oak species and to forecast their future performance under warm(4.8℃)conditions in the Iberian Peninsula.Our simulations indicate that climate warming would induce a shortening of the ringgrowth season and a reduction of radial growth in evergreen and deciduous Mediterranean oaks,particularly in dry sites from southern and eastern Iberia currently occupied by Q.ilex and Q.faginea.Evergreen oaks may better recover after dry periods than deciduous oaks by resuming growth after the summer drought.Low soil water availability in spring would be more detrimental to growth of deciduous oaks.Process-based growth models should be refined and validated to better forecast changes in tree growth as a function of climate.

Climate-driven variations in productivity reveal adaptive strategies in Iberian cork oak agroforestry systems

Background:Cork oak agroforestry systems(AFS)have been managed for centuries by humans to produce cork and other goods and services and have recently been recognised as an important reservoir for biodiversity improvement and conservation.However,despite having recently been included as a natural habitat of community-wide interest within the EU Habitats Directive,these systems are in a critical situation of decline.Among other factors,they are strongly threatened by climate change,the effects of which are also expected to be particularly severe in the Mediterranean region.In this study,we aimed to evaluate the influence of climate variability by examining primary production indicators and also to analyse whether the geographical location may have a role in the incidence of the adverse effects of climate.Methods:Cork oak AFS were identified in the Forest Map of Spain and the Land use map of Portugal and categorized on the basis of canopy cover.Seasonal climate data from 2001 to 2020 were used to model relationships with climate predictors and proximity to the coast.Hotspot analysis was conducted to identify significant spatial clusters of high-and low-efficiency areas.Results:The responses to the influence of climatic conditions differed among the various cork oak AFS categories,particularly in the forest category,which was less dependent on climate variations.Relative humidity and water availability were the main drivers of net primary production(NPP).Carbon use efficiency(CUE)was limited by relative humidity and spring temperature in open ecosystems.Proximity to the coast proved beneficial,especially in years with adverse weather conditions,but was not a limiting factor for survival of the ecosystem.Finally,the results of the hotspot analysis supported the other findings,highlighting high-efficiency areas close to the coast and cold spots grouped in specific areas or dispersed inland.Conclusions:Canopy plays a key role in the influence of climatic conditions,particularly in forest categories in which a high density seems to generate microclimate conditions.Water availability,both via the soil and air moisture,is the main driver of primary production,reflecting different adaptive strategies.The oceanic atmosphere may act as a buffer in years of extreme drought.

Vegetation Dynamism in the Mixed Conifer/Broadleaves Species Artificial Stands Crossed by Fire： The Arci Mountain Case Study in Sardinia

Immediate cutting and logging of mixed conifer/broadleaves species in a man-made forest crossed by fire in 2009 in the Arci Mountain in Sardinia can not guarantee as the best post-fire regeneration. The study case reports the differences in the density and in the height of seedlings. The release of damaged Pinus halepensis Mill. stems seems to confirm the tree seeder role of this species.

Field trapping of the flathead oak borer Coroebus undatus （Coleoptera： Buprestidae） with different traps and volatile lures

The flathead oak borer Coroebus undatus E （Coleoptera： Buprestidae） is one of the primary pests of cork oak Quercus suber L. in the Mediterranean region causing great economic losses to the cork industry. Very little is known about its biology and behavior and, so far, no control measures have been established. We present the results of a pilot study aimed to develop an efficient trapping method for monitoring this harmful pest. In a 3-year field study, purple-colored prism traps baited with a mixture of green leaf volatiles （GLVs） from the host have been shown the most effective combination to catch C. undatus adults （solely females） compared to other trap and lure types tested. Wavelength and reflectance measurements revealed that purple traps exhibit reflectance peak values similar to those found in the abdominal and elytral cuticle of both sexes, suggesting the involvement of visual cues for mate location in this species. The data presented are the first to demonstrate captures of adults of the genus Coroebus by an attractant-based trapping method.