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The wood borer Cerambyx welensii Küster is a key contributor to Quercus open woodland (dehesa) decline. Among other factors, olfactory and visual cues could influence host colonisation by this species. In this study, we investigated whether the physiological performance and morphological features of Q. suber trees under summer stress are affected by C. welensii infestation. Additionally, we analysed the relation between morpho-physiological variables and the emission of monoterpenes that potentially mediate host selection by C. welensii. Thirty-six Q. suber trees with known monoterpene emission profiles were selected: 18 trees highly visited by C. welensii, and 18 neighbouring trees not visited or at least not visibly damaged by this wood borer. For each tree, we assessed photosynthesis, stomatal conductance, and transpiration during the early evening, and also the perimeter and crown projection. Trees visited by C. welensii maintained higher photosynthetic activity than non-visited trees (1.5–2.15 times) from 19:35 to 20:45 h. Visited trees had larger perimeters and smaller crown projection area-to-perimeter ratios than non-visited trees. Results suggest that, under stress conditions, the physiological performance of trees infested by C. welensii could have favoured foliar emission of certain monoterpenes influencing intraspecific host selection by this species. [ABSTRACT FROM AUTHOR]

In Mediterranean climate regions, climate change is increasing aridity and contributing to the mortality rate of Quercus suber, reducing the success of reforestation efforts. Using and creating microclimates is a recommended climate adaptation strategy that needs research. Our hypothesis is that planting Q. suber in north-facing slopes and water lines results in a higher survival rate than those that are planted in ridges and south-facing slopes. Secondly, our hypothesis is that existing shrubs (in this case, Cistus ladanifer) can be used to create microclimatic sheltering and increase the survival of Q. suber plantations. In experiment 1, we tested the survival of Q. suber plantations in four different topographic conditions. For that, 80 Q. suber plants were planted over four different topographic conditions, where soil probes were installed to monitor soil moisture and temperature. Two years after, the results show an increased survival rate in the north-facing slope and water line when compared to the ridge area (p = 0.032). In experiment 2, we tested if planting in the shade of rows of C. ladanifer increases the survival rate of Q. suber plantations. For that, 1200 Q. suber plants were planted; 600 in a Montado open area with no shade and 600 under the shade of rows of C. ladanifer shrubs. A total of 17 months after plantation, there was a significantly higher survival rate of the shaded plants (p = 0.027). We conclude that microclimates created by topography and shrubs can have a significant impact on the survival of Q. suber plantations and discuss the situations in which these can apply. [ABSTRACT FROM AUTHOR]

The necessity for accurate biomass estimates is greater than ever for the sustainable management of forest resources, which is an increasingly pressing matter due to climate change. The most used method to estimate biomass for operational purposes is through allometric equations. Typically, each country develops their own models to be applied at the local scale because it is more convenient. But, for Quercus suber, a joint regional model can be more beneficial, since the species is distributed across the Mediterranean and is challenging to account for due to felling limitations and the nature of mature cork biomass itself. We found that these characteristics are reflected in the biomass datasets and compatibility was, perhaps, the largest impediment to such a model. The use of dummy variables to differentiate between countries, as well as compromises in the limits of biomass compartments, allowed us to develop two joint models to estimate aboveground biomass in Portugal, Spain and Tunisia. One model as a function of diameter and another as a function of diameter and total tree height. In addition, we developed a separate model for roots (modelling efficiency of fitting = 0.89), since it was not possible to assure additivity of the whole tree. All coefficients were estimated using Seemingly Unrelated Regressions (SUR) and model fitting assured additivity in the aboveground compartments—leaves and woody biomass (modelling efficiency of fitting = 0.89 and 0.93, respectively). This work proves that it is possible to have a biologically sound and efficient model for the three countries, despite differences in the observed allometric patterns. [ABSTRACT FROM AUTHOR]

In Spain, natural and managed cork oak woodlands are severely affected by decline caused by the root rot oomycetes Phytophthora cinnamomi and Pythium spiculum. The need for environmental-friendly disease management makes the use of resistance inducers a suitable option. As the use of phosphite is prohibited in Spain, trunk injections of fosetyl-aluminium were tested in a seminatural cork oak woodland (dehesa). Sixty cork oaks in three different defoliation classes (asymptomatic, slight, and moderate defoliation) were selected for fosetyl- aluminium or control (water) trunk injections, and periodically checked for defoliation and presence of both pathogens in roots and rhizosphere soil. Three years after treatments, fosetyl-aluminium injection significantly decreased defoliation in treated cork oaks in comparison with water-injected controls, regardless of the initial defoliation class considered. Changes in inoculum density in the rhizosphere or presence of the two pathogens in roots were not significantly dependent on treatment. However, a trend to a lower presence of pathogens in roots of treated oaks was observed with increasing soil inoculum densities. Fosetyl-aluminium, a phosphonate fungicide registered in the European Union, was experimentally proved to protect cork oaks against root rot caused by P. cinnamomi and Py. spiculum, even exhibiting a therapeutic effect on preexisting infections. This effective measure can therefore be used to fight against this highly destructive disease in seminatural woodlands and in protected natural ecosystems. [ABSTRACT FROM AUTHOR]

Mediterranean wooded grasslands are multipurpose systems that support high plant and animal diversity levels and are habitats of European importance (i.e., 6310 – Dehesas with evergreen Quercus spp.). Moreover, these systems offer a number of agro-ecosystem services such as forage production, soil carbon sequestration, nutrient recycling and soil protection. The scattered trees enhance the ecological complexity of grassland influencing the soil properties, the herbaceous layer diversity and composition and the soil communities. Understanding how isolated trees influence the other components of the system is essential to comprehend their role supporting high levels of above and below ground biodiversity and ecosystem services. In the present study, we present a hypothetical framework of the effects of isolated trees on soil properties, plant and soil fauna assemblages, the latter here represented by the class Collembola. The floor litter and the associated input of organic matter to the soil was a key factor linking the components of the tree-soil-biodiversity system in a Mediterranean cork oak wooded grassland. Topsoil C increased by +50% under the tree canopy in comparison with the areas beyond the tree canopy. Plant diversity was lower under tree canopy, but contributed to enhance the total species richness of the grassland. Collembolan diversity was higher under the peculiar conditions beneath the tree canopy. Relationships between plant and collembolan species emerged. The findings of this study suggest that isolated trees have direct and indirect effects on soil properties, plant and collembolan assemblages, hence they can influence the ecological processes of wooded grasslands, with implications for food webs, nutrient cycling and productivity of the agro-ecosystem. [ABSTRACT FROM AUTHOR]

Modern alley cropping designs, with trees aligned in rows and adapted to operating farming machinery, have been suggested for Europe. This paper explores the potential for adoption of cork oak ( Quercus suber L.) agroforestry in Portugal and estimates the potential carbon sequestration. Spatial modeling and Portuguese datasets were used to estimate target areas where cork oak could grow on farmland. Different implementation scenarios were then modeled for this area assuming a modern silvoarable agroforestry system (113 trees ha thinned at year 20 for establishing 50 trees ha). The YieldSAFE process-based model was used to predict the biomass and carbon yield of cork oak under low and high soil water holding capacity levels. Approximately 353,000 ha are available in Portugal for new cork oak alley cropping. Assuming implementation rates between 10 % of the area with low soil water capacity (60 mm: 15 cm depth, coarse texture) and 70 % of the area with high soil water holding capacity (1,228 mm: 200 cm depth, very fine texture), then carbon sequestration could be 5 × 10 and 123 × 10 Mg CO respectively. Due to higher yields on more productive land, scenarios of limited implementation in high productivity locations can sequester similar amounts of carbon as wide implementation on low productivity land, suggesting that a priori land classification assessments can improve the targeting of land and financial incentives for carbon sequestration. [ABSTRACT FROM AUTHOR]

Different management practices are commonly applied to increase pasture yield of Mediterranean open woodlands, but the consequences of increasing competition for soil resources with these practices on tree recruitment are still unknown. In a greenhouse study, belowground competition of Quercus suber L. seedlings growing together with natural (Oak) or improved pasture (Oak) was evaluated, and their root systems compared with those of seedlings growing in bare soil (Oak). Two watering levels and two regimes of PO fertilisation were also tested. Because of competition, the Oak seedlings had their fine root mass density, coarse root length, and shoot mass reduced by up to 40, 36, and 39%, respectively, when compared to Oak seedlings. Oak and Oak seedlings showed similar average root density parameters and shoot mass values, indicating that Q. suber seedlings growing with natural pasture is a low competitive system. High availability of water and phosphorus did not mitigate the strength of competition between herbaceous plants and oak seedlings, and favoured the pasture to the detriment of the trees. Our findings suggest that PO fertilisation and irrigation practices performed to improve herbaceous productivity will negatively influence recruitment of Q. suber seedlings. [ABSTRACT FROM AUTHOR]

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The Portuguese montado is an agro-silvo pastoral system quite similar to the dehesa in Spain, and covering in Portugal most of the Southern region of the country, Alentejo. The trees in the montado are cork oh holm oak, and the system is mostly acknowledged due to the cork production, but also due to its singular savanna like land cover pattern, its multiple and complementary productions, the support of a diversity of ecosystems services and its biodiversity. The present special issue covers the diversity of components of the montado and of perspectives required to understand and assess the functioning of the system. This Editorial introduces the montado system, describes its extension and similarities to the dehesa in Spain, and addresses the multiple productions and externalities of the montado. It also refers to the several components of the system. It focus on the uniqueness and values of this system, stressing its potential and threats, and the requirements for integrated knowledge production. In the end of the Editorial, each one of the papers that compose the special issue are presented. [ABSTRACT FROM AUTHOR]

Abstract: The montado is an agro-silvo pastoral system characterized by an open oak formation combined with shrubs or a rotation of cultures/pastures/fallow. A key, but frequently overlooked, component of these systems is the fungal community associated with the dominant oaks. We present a study of the basidiomycete community in montado areas of Quercus suber L. from Central-Western Portugal, based on fruiting body assessment and PCR-DGGE of soil mycelium. Soil available phosphorus and organic matter content were also determined. The most frequent fruiting body found in the cork oak montados belonged to Lactarius, Clitocybe, Russula and Cortinarius species. Lactarius chrysorrheus was the most widely distributed species. Soil management practices cause a temporal increase in soil available phosphorus, and harrowing and fertilizer application also result in an increase in soil organic matter content. Mechanical clearing with recent soil disturbance had a negative effect on the richness and diversity of the basidiomycete community assessed using fruiting body. The molecular analysis of the basidiomycete community separated the sites with recent shrub-removal from the others sites. Our results show that soil management techniques that avoid disturbance of the top-soil layers are the best way to preserve the structure and diversity of the soil fungal community in the montado. [ABSTRACT FROM AUTHOR]

This work assesses damage caused by Coraebus undatus (Fabricius) (Coleoptera: Buprestidae) and Reticulitermes grassei Clément (Blattodea: Rhinotermitidae) in managed cork oak forests from the southern Iberian Peninsula. Lesions were diagnosed and quantified in relation to the following features: height and orientation in the trunk, diameter at breast height, solar exposure, understory presence and orography. The distribution patterns of lesions in the study area across 12 plots and in the trunk of the trees were also analyzed. The study was performed in "Sa de Hornachuelos" Natural Park (Córdoba, Spain) and the research area encompassed 12 environmentally-restored sampling plots. Data were recorded from 2007 to 2014, with yearly sampling from late June to mid-September, corresponding to the cork extraction period, since lesions caused by these insects are well distinguishable promptly after bark removal. The results reveal that C. undatus has low population levels and a non-uniform distribution pattern in the study area as well as in the trunk of the tree. It shows preference for medium height but not by any trunk orientation. R. grassei also shows low infestation levels and a preference to affect the trunk's base. Comparatively, C. undatus showed higher infestation levels than R. grassei. The location of damage was also different, since galleries made by C. undatus predominated at intermediate trunk heights while those of R. grassei were more frequent at lower heights. Our results further showed a low co-occurrence of both species in the same tree trunks, which could be explained in terms of overlapping in the distribution areas of both species. These results provide background information that will enable natural resources managers to detect changes and trends of these species and inform future management decisions. [ABSTRACT FROM AUTHOR]

Plant diversity and proxy indicators of ecosystem services were assessed for three structural components of Mediterranean silvopastoral agroforestry systems: WL = cork oak woodlands, WG = cork oak wood grasslands, and OG = open grasslands. Our study was conducted in a long-term observatory located in NE Sardinia, characterized by fragmented land ownership and land use, which generates a patchy landscape that is different from the extensively studied large scale Iberian dehesas and montados. Our research question was focused on assessing whether, a "patchy" land use scenario made of the combination of WL, WG and OG or a "specialized" scenario could provide more plant diversity and ecosystem services than a " dehesa type" scenario including only WG under the same overall tree cover. The results showed that γ and β diversity, species unique to a position, C stock, cork and acorn production, Hemicryptophytes cover, nectariferous species cover, decreased and pastoral value, excellent and good forage species and legume cover, increased along the WL➔WG➔OG land use gradient. Isolated trees in WG and clearings in WL highly contributed to achieving mainly high C stock and plant diversity respectively. The results also showed that the "specialized" scenario can support higher biodiversity and better ecosystem services than the " dehesa type" scenario, but the "patchy" scenario made of all three components proved to support the highest level of both biodiversity and ecosystem services in Mediterranean silvopastoral agroforestry systems. • Woodlands, open and wood grasslands are key components of silvopastoral systems. • Biodiversity and C stock decreased with silvopastoral land use intensity. • Pastoral value and in situ valuable germplasm increased with land use intensity. • Clearings in cork oak woodlands enhanced C stock and plant diversity. • A patchy landscape is ideal for enhancing plant diversity and ecosystem services. [ABSTRACT FROM AUTHOR]

• Cork oak forests are declining across Southwestern Europe. • We assessed the incidence of canopy insect pests in cork oaks agroforests. • Most insect pests benefited with agroforestry intensification. • Diversification of tree species and ages may contribute to reduce oak pest impacts. The decline of oak (Quercus spp.) forests is a current trend in Northern Hemisphere and is characterized by a loss in tree vigour and increased mortality. The canopy insects are suspected to have role in this decline, but there is poor knowledge about their incidence in evergreen-oak stands. The main aim of this study is to characterize the incidence of main insect groups affecting branches and leaves of an evergreen-oak species (the cork oak Quercus suber) and evaluate which management practices and environmental traits of agroforestry systems affect it. In the spring/summer of 2018, we measured the incidence of attacks on branches and leaves by gall-makers (Diptera, Cecidomyiidae), blade-miners (Lepidoptera and Coleoptera), midrib-miners (Lepidoptera, Heliozelidae), chewer caterpillars (Lepidoptera), chewer sawflies (Hymenoptera, Tenthredinidae), weevils (Coleoptera, Curculionidae) and branch-borers (Coleoptera, Buprestidae). We analysed the frequency of pest signs according to different indicators: management practices, tree maturity, forest diversity, forest fragmentation, and latitude and longitude. The most frequent signs of insect pests on tree leaves corresponded to blade-miners, midrib-miners, chewer caterpillars and chewer sawflies. With exception of midrib-miners and branch-borers, all insect pests were found on cork oak stands experiencing decline and benefited from management intensification. Our study suggests that a diverse-aged stand may reduce the frequency of midrib-miners and chewer caterpillars, as well the attack of branch-borers. Moreover, a high plant diversity in forests can contribute to reduce the impact of defoliators on cork oaks (e.g., chewer sawflies) and understory reduction decreased the exposure of trees to gall-makers. Moreover, we found that forest fragmentation may increase the frequency of blade-miners and chewer caterpillars. We conclude that insect pests have a high incidence in cork oak stands and thus, may have and important role in its decline. Considering that a high frequency of pests is often associated with increased management intensity, a change to a more sustainable use of these systems is urgently needed. [ABSTRACT FROM AUTHOR]

Key message: Cork oaks highly infested byCerambyx welensiiemit an amount of limonene at dusk, whenC. welensiiadults become active. In contrast, emissions by neighboring cork oaks free ofC. welensiiare dominated by pinene-type compounds. Context: The activity of the woodborer Cerambyx welensii Küster is a key factor in the decline of Quercus suber L. dehesas. Aims: This study aimed to estimate whether trees highly infested by C. welensii exhibited a peculiar emission profile, with known antennally active compounds. Methods: Monoterpenes were sampled in situ in 2006 (day/late evening) and 2008 (early evening) from Q. suber stratified by whether or not trees were highly infested by C. welensii and analyzed by gas chromatography. Results: Limonene, α-pinene, β-pinene, sabinene, and myrcene accounted for over 87.2% of overall monoterpene emissions. Monoterpene composition and emission rates differed between the two groups, both during daytime and early evening, with a high presence of limonene in infested trees and dominance of pinene-type compounds in non-infested trees. Conclusion: This work evidenced differences in foliar monoterpene emissions between Q. suber trees highly infested by C. welensii and non-infested trees, with a high presence of limonene in the former and dominance of pinene-type compounds in non-infested trees. We hypothesize that the detection—especially during the onset of insects daily flight—of certain compounds (e.g., limonene), together with the detection of specific ratios of several monoterpenes (e.g., those of limonene to pinene-type compounds), has a role in the intraspecific host selection by C. welensii. [ABSTRACT FROM AUTHOR]