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Essential oils (EOs) obtained from Juniperus communis L. are frequently used in the production of bioproducts. However, there are no studies regarding industrial crops' production, allowing for better control of the quality and production of juniper EOs. To select the plant material for developing future crops of this species in northern Spain, four locations where this shrub species grows in the wild were selected and samples of both genera were collected. The EOs were obtained by steam distillation, and their chemical composition and bioactivity were evaluated. The results showed that the yield of EOs from male and female samples were within the usual reported ranges, varying between 0.24 and 0.58% (dry basis, d.b.). However, limonene content in three locations varied between 15 and 25%, which is between 100% and 200% higher than the values usually reported for other European countries. The antibacterial activity was determined by broth microdilution and showed that gram-positive bacteria were more susceptible to the tested EOs since, in general, lower MIC values were obtained compared to gram-negatives. The EOs from location 1 (L1F) and 2 (L2M) inhibited the growth of six out of the eight clinical strains tested. Samples from location 1 were particularly effective, exhibiting MBC against two gram-negative (E. coli and P. mirabilis) and one gram-positive bacteria (E. faecalis). Moreover, the majority of the EOs tested showed anti-inflammatory activity. Cytotoxic effect has been demonstrated in tumor cell lines, with the best results observed against gastric carcinoma (AGS) cells (GI50 between 7 to 77 µg/mL). Although generally presenting higher GI50, most samples also inhibited the growth of non-tumoral cells, particularly hepatocytes (PLP2 cells). Therefore, its use for their anti-proliferative activity should consider specific conditions to avoid damaging normal cells. Finally, the results and conclusions obtained led to the selection of the female shrubs from location 1 (L1F) as the plant material to be propagated in order to produce plants for a future juniper crop. [ABSTRACT FROM AUTHOR]

Juniperus communis L. is a species commonly grown in regions of the Northern Hemisphere, and is a good candidate to be cultivated in marginal lands. Plants coming from a pruning performed in a natural population located in Spain were used to assess the yield and quality of different products obtained following the cascade principle. A total of 1050 kg of foliage biomass were crushed, steam-distilled, and separated into fractions to produce biochar and absorbents for the pet industry using pilot plants. The obtained products were analysed. The essential oil, with a yield of 0.45% dry basis and a qualitative chemical composition similar to that described for the berries in international standards or monographs, showed antioxidant activity with promising CAA results (inhibition of 89% of the cell's oxidation). However, regarding antibacterial and antifungal activities, it only inhibited the growth of microorganisms at the maximum concentration tested, 2.5%. Concerning the hydrolate, it did not show bioactivity. Regarding the biochar, whose yield was 28.79% dry basis, interesting results were obtained for its characterisation as a possible soil improver for agronomic purposes (PFC 3(A)). Finally, promising results were obtained regarding the use of common juniper as absorbent, taking into account the physical characterisation and odour control capacity. [ABSTRACT FROM AUTHOR]

Wildfires affect the structure, functioning, and composition of ecosystems. Long-term monitoring of the occurrence, abundance, and growth of plant species is key to assessing the responses of the dynamics of plant populations with regard to environmental disturbances, such as wildfires. In this work, we evaluated the changes in the number of individuals and the canopy cover extent of a population of Juniperus communis L. during a four-decade period following a wildfire in a Mediterranean high-mountain ecosystem (Sierra Nevada, Spain). To do this, we used object-based image analysis (OBIA) applied to very high-resolution aerial images. Our study also provides a new approach to optimize the shrub identification process and to semi-automatically evaluate the accuracy of the number of shrubs and their canopy cover. From the 752 individuals present in 1977, only 433 remained immediately after a fire (1984), a few more disappeared one decade later (420 shrubs in 1997), while by 2008, the population had partially recovered to 578 shrubs. The wildfire decreased juniper canopy cover from 55,000 m2 to 40,000 m2, but two decades later it had already recovered to 57,000 m2. The largest shrubs were more resistant to fire than the smallest ones and recovered in a shorter time period. The protection measures introduced with the park declaration seemed to have contributed to the post-fire recovery. The potential of this methodology in the management and conservation of biodiversity in the future is also discussed. [ABSTRACT FROM AUTHOR]

Purpose: The transformation of extractable plant compounds after their incorporation into soil was qualitatively and quantitatively studied in two forests under Juniperus communis L. and Pinus sylvestris L. Methods: Leaf, litter and soil samples were taken from representative pine and juniper forests in central Spain. The lipid fraction was extracted with dichloromethane, while methanol was used for polar compounds, which were then derivatized (silylation-oximation). Extracts were analyzed by gas chromatography-mass spectrometry. van Krevelen's graphical-statistical method, enhanced as surface density maps, was used to study changes in molecular assemblages during their transformation from plant to soil. Shannon Wiener diversity indices were also determined for the main groups of molecules to quantify the progressive removal or the appearance of new compounds throughout the transformation. Results: In the lipid fraction up to 126 compounds were identified, mainly alkanes (C10–C30 in pine forest and C10–C36 in juniper forest), fatty acids and cyclic compounds. In the polar extracts, up to 22 compounds were found, mainly sugars, polyols, cyclic acids and fatty acids. Conclusion: Comparing the successive stages of evolution of leaf extractive compounds, alkanoic acids and disaccharides tend to accumulate in the soil. On the other hand, the greatest molecular complexity was found in the intermediate stage (litter), and attributed to the coexistence of biogenic compounds with their transformation products, while the molecular complexity was simpler in soil extracts. This preliminary investigation could be extended to specific studies on the factors that determine the quality of soil organic matter under different environmental scenarios. [ABSTRACT FROM AUTHOR]

Assessing post-fire recovery is essential to forecast how ecosystems will respond to future warmer conditions and higher fire severity. Such assessments must consider site conditions and the post-fire recovery of trees and shrubs. We used tree-ring data and intrinsic water-use efficiency (WUEi) to quantify the post-fire responses of a tree (Pinus pinea) and a shrub (Juniperus phoenicea) in Mediterranean coastal dunes located in the Doñana protected area, SW Spain. We compared pines and junipers growing in an inter-dune slack with those growing in a nearby dune ridge. We quantified crown damage and bark char in pines impacted by a wildfire. Pines with lower crown damage after the fire showed a higher growth rate one year later. Growth decreased afterwards in the case of fast-growing pines from the slack site, whereas slow-growing dune pines showed increasing growth rates one to three years after the fire. The fire did not change the pines' WUEi, whereas the junipers located in dunes presented the highest WUEi values. Severe crown damage (damage > 60%) impairs long-term growth recovery in P. pinea. Open and heterogeneous landscapes can reduce the wildfire risk in the study Mediterranean area, where slack vs. dune and tree vs. shrub differences should be considered in post-fire management plans. [ABSTRACT FROM AUTHOR]

We analyzed the relationship between forest productivity (joint effect of forest maturity and soil quality) and total soil respiration (µmol CO2 m−2 s−1) in semi-arid juniper woodlands (young woodlands growing in abandoned farmlands with deeper soils, and mature woodlands in lithic soils), and investigated the seasonal variation in soil CO2 efflux as a function of soil temperature and the soil water content. We measured the soil CO2 efflux from twelve cylinders in the soil over a three-year period using LI-6400 equipment. The results show that, in the more productive site (young woodland), soil CO2 efflux was higher due to greater respiration, mainly in the driest periods. Soil respiration followed a seasonal trend, being higher in spring and decreasing in cold periods. In both juniper woodlands and especially in the older forest, the CO2 efflux rates were low (<2.5 for Q10), typical of slow-growing species. Soil respiration was controlled by soil temperature without drought and in the temperate-warm season, whereas respiration showed sensitivity to soil water content in periods when edaphic humidity was low (but only in the more productive, young forest, which seemed to show better adaptation to drought), and under high soil moisture (soil water > 25%) for both woodlands, coinciding with warm temperatures in the spring. This period also corresponded to the highest CO2 efflux recorded in both woodlands. The accumulation of organic C seems to also be important to maintain elevated soil respiration in summer, especially in young woodlands. Thus, apart from microclimatic conditions, factors related to productivity regulate respiratory activity. [ABSTRACT FROM AUTHOR]

Key message: The dioecious tree species Juniperus thurifera L. is undergoing a spontaneous process of forest expansion in southwest Europe. We investigated how growth, climate sensitivity, and wood density varied simultaneously between sexes and among stages of expansion while accounting for the variability of forest structure. We found few sex-based differences but detected lower wood density, greater growth rates, and higher sensitivity to drought in expanding fronts compared to long-existing forests. Context: Juniperus thurifera L. (Spanish juniper) is a dioecious tree species undergoing a natural process of forest expansion in southwest Europe. Aims: To assess how radial growth and wood density are simultaneously shaped by sex-based differences, the stage of forest expansion (long-existing forests, transition zones, and expanding fronts), variability in forest structure, and climate (in the case of radial growth). Methods: We measured forest structure characteristics, tree rings, and wood density in 17 plots dominated by Spanish juniper in three stages of forest expansion in central Spain. We used linear mixed models (LMMs) to explore the main drivers of variability in radial growth and wood density and sex- and stage-based differences in climate-growth sensitivity. Results: Rather than by sex, growth and wood density were mainly shaped by the stage of forest expansion, forest structure variables that characterize these stages, and climate variables (in the case of growth). Conclusion: Sexual dimorphism had a minimal effect in growth and wood density in expanding Spanish juniper woodlands. Expanding fronts could be benefiting from land-use legacies in the abandoned fields they are colonizing, as reflected in higher growth rates and lower wood density, especially during years with less summer drought stress. However, this pattern could be reversed in the event of an increase in drought episodes. [ABSTRACT FROM AUTHOR]

• Which traits provide post-drought growth resilience to trees and shrubs? • We answered this issue by analyzing 19 conifers from climatically contrasting sites. • Growth resilience was negatively related to plant height. • Resilience was positively related to (hydraulic diameter / cell-wall thickness). • Growth recovery was positively related to the growth responsiveness to climate. Warmer and drier climate conditions are negatively impacting conifers, which show different mechanisms to withstand drought stress including growth resilience. However, it is unclear which traits make trees and shrubs more resilient to drought in terms of growth recovery. We addressed this question by measuring and collecting from the literature several functional traits in 19 conifers of nine genera (Abies, Pinus, Pseudotsuga, Cedrus, Picea, Juniperus, Cupressus, Tetraclinis and Taxus) from three families (Pinaceae, Cupressaceae, Taxaceae) inhabiting sites of contrasting climate conditions in Spain. These traits were correlated with three growth resilience indices derived from ring-width data (Rt, resistance; Rc, recovery; Rs, resilience) with and without accounting for their phylogenetic signal. Growth resistance (Rt) was negatively related to plant height (r = -0.52, p = 0.04). Growth resilience (Rs) was negatively related to plant height (r = -0.93, p < 0.001) and leaf life span (r = -0.51, p = 0.03), but positively related to the thickness-to-span ratio (r = 0.80, p < 0.001). However, the relationship between Rs and leaf life span was not significant (p = 0.155) after accounting for phylogenetic signals. Lastly, growth recovery was positively related to the growth responsiveness to climate, assessed as the correlation between ring-width indices and water balance (r = 0.66, p = 0.002). Height and the thickness-to-span ratio, a surrogate of xylem resistance to cavitation, are linked to post-drought growth recovery in conifers subjected to seasonal dry conditions. [Display omitted] [ABSTRACT FROM AUTHOR]

Key message: In our study of colonisation of abandoned farmland byJuniperus thuriferaL., environmental and geographic distances were stronger drivers of functional differentiation among trees than genetic distance and tree intrinsic features. However, these effects varied both along the colonisation gradient and across predictors' values, highlighting the complexity of the conditions under which functional diversity of forests is maximised. Context: Forest expansion after land abandonment is changing Mediterranean landscapes, but the underlying ecological and evolutionary processes remain poorly understood. Aims: We evaluated whether forest expansion reduces within-stand tree functional distances and whether its environmental, geographical and genetic drivers vary along the expansion gradient. Methods: We sampled Juniperus thurifera in mature, transition and expanding stands along a colonisation gradient in Spain. We measured functional traits, genetic relatedness, surrounding vegetation cover and intrinsic features (size, phytosanitary status) on trees. We calculated within-stand pairwise functional distances and quantified the effects of genetic relatedness, geographic distance, vegetation cover and intrinsic tree features. Results: Functional and genetic distances showed no consistent patterns along the expansion gradient. Functional distance was unrelated with genetic distance and strongly driven by geographic distance, likely representing unmeasured environmental factors. Vegetation cover and intrinsic tree features affected functional traits in transition and expanding stands. The effects on functional distance changed across predictors' values. Conclusion: The role of environmental and geographic factors on tree functional divergence varied along the farmland colonisation gradient, while we did not detect effects of genetic distance. Accounting for this context-dependence and for non-linear effects on functional traits can improve our understanding and management of forest expansions. [ABSTRACT FROM AUTHOR]

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I studied the effects of browsing by red deer (Cervus elaphus) on the growth, composition, structure and succession of a stand of the dioecious maritime juniper (Juniperus macrocarpa) in the moving dunes of the Doñana National Park (SW Spain). A deer exclosure experiment was initiated in 1999 and plant growth was monitored for 22 months. In 2007, height and sex were determined in 100 juniper plants inside the exclosure and 100 in the adjacent open area. Finally, in 2010 woody plant composition, structure and diversity was measured in both treatments and compared with previous data. Junipers showed continuous growth throughout the year, with the highest growth being recorded in the rainiest part of the year (autumn, winter or spring). Browsing took place mainly in autumn and winter, but extended to spring and summer. Junipers inside the exclosure showed higher growth when compared to junipers in the open area except for the summer, when herbivory decreased and unfenced junipers showed a compensatory response. In 2007, there were more female plants in the exclosure (35%) than in the open area (3%), while the number of unsexable individuals was larger in the open area (74%) than inside the exclosure (38%), suggesting a selective browsing on female individuals by red deer. Plant species richness did not change during the study period, but the community previously dominated by Helichrysum picardii became dominated by maritime juniper, increasing in cover from less than 7% to 46%. These results supported the hypothesis that browsing by red deer led to a state of arrested succession, maintaining small plants and open zones. Control of red deer density or access may be an option for improving maritime juniper reproduction and for releasing maritime juniper woodlands from arrested succession. [ABSTRACT FROM AUTHOR]

Over the last few decades, abandonment of traditional management practices in Spain has led to widespread stand densification and has favoured the expansion of some forest species that previously exhibited more restricted ranges. Spanish juniper ( Juniperus thurifera L.) woodlands are experiencing this phenomenon due to agricultural land abandonment and a decrease in the livestock pressure. Yet the main drivers underlying stand structure and dynamics at this novel scenario are poorly understood. In this study, we investigate the main biotic drivers of tree growth in a high-density stand of the dioecious J. thurifera at an early developmental stage (mean tree age of 32, ca. 50 years after land abandonment). Tree growth was measured by coring 299 individuals of different reproductive classes (male, female and non-reproductive). Neighbourhood models were used to assess the relative importance of tree size and neighbourhood competition on tree growth of each reproductive class in the study plot. We found that tree size had the strongest effect on tree growth, whereas the effect of intraspecific competition was negligible. We observed differences in growth patterns among reproductive classes along trunk diameter sizes. Thus, at smaller sizes, the three reproductive classes presented identical patterns of growth. However, at bigger sizes, females were the fastest growing individuals, followed by males and non-reproductive individuals. Overall, our results suggest that in young J. thurifera monospecific forests, where self-thinning processes may have not undergone yet, tree size and the reproductive class could play a relatively more important role than competition as drivers of tree growth. These findings constitute new information which contributes to understanding growth dynamics at early developmental stages in this dioecious species. Furthermore, our results provide guidelines for silvicultural managing, suggesting that at these young juniper stands thinning would likely not translate into enhanced growth on remnant trees. [ABSTRACT FROM AUTHOR]

We explored the effects of tree-fall gaps caused by Heterobasidion annosum- induced tree death on the regeneration of the relict Abies pinsapo in southern Spain. We analyzed the structure and regeneration of A. pinsapo in 44 circular closed-canopy plots and 11 gaps (mean size 75 m2) located in H. annosum infection foci. We measured adult density, basal area, and height of all tree species with a diameter at breast height greater than 7.5 cm and quantified regeneration abundance. Diameter structures were analyzed using Weibull functions. A. pinsapo comprised 49-81% of total adult tree density (358-1418 trees ha-1) and total basal area (15.70-39.22 m2 ha-1). Density of A. pinsapo juveniles ranged from 129 to 416 individuals ha-1, while that of juveniles of other tree species such as Quercus ilex was much lower. A. pinsapo saplings and seedlings were more abundant within gaps than in closed-canopy sites. A. pinsapo regeneration was related to the tree species composition of the stands adjacent to gaps. The main potential species replacing A. pinsapo in H. annosum- induced gaps were, in decreasing order of importance, Quercus ilex, Q. faginea, and Juniperus oxycedrus. The current stand structure and gap-infilling processes suggest that A. pinsapo regenerates adequately within H. annosum- induced gaps. However, the relative proportion of other coexisting tree species within H. annosum-related gaps will increase substantially over time as compared with closed-canopy areas. [ABSTRACT FROM AUTHOR]

Juniperus thurifera L. is an important tree endemic to the western Mediterranean basin that it is able to grow in semi-arid climates. It nowadays exhibits a disjunct distribution pattern, occurring in North Africa, Spain, France and the Italian Alps. The Strait of Gibraltar has acted as an efficient barrier against gene flow between African and European populations, which are considered different subspecies by some authors. We aimed at describing the intraspecific genetic diversity of J. thurifera in populations from the Iberian Peninsula and Morocco and the phylogeographical relationships among these populations. The ploidy level of J. thurifera was examined and eleven nuclear microsatellites (nSSRs) developed for J. thurifera were assessed for genotyping this species. Six nSSRs were polymorphic and subsequently used to assess the genetic diversity and structure of the studied populations. Genotyping of the tetraploid J. thurifera using nuclear microsatellites supports the separation of Moroccan and Spanish populations into two genetically differentiated groups that correspond to the proposed subspecies africana and thurifera. High values of within population genetic diversity were found, that accounted for 90% of the total genetic variance, while population structure was weak. The estimators of genetic diversity were higher in populations of Spain than in populations of Morocco pointing for a possible loss of genetic diversity during the spread of this species to Africa from Europe. [ABSTRACT FROM AUTHOR]

This work addresses the structural characterization of Juniperus oxycedrus-dominated woodlands in west-central Spain, as well as the analysis of the regeneration of this species in the presence of other species (mainly Quercus ilex) as a function of different environmental and land-use factors. The two densest populations of the species were sampled and different physiographic and land-use parameters were obtained. First, a structural characterization, specifically focused on regeneration, was carried out, based on the count of individuals and their classification according to their size (seedlings, saplings, or adults) and position (either beyond or below the canopy). The use of Generalized Linear Models (GLM) and Regression Trees permitted the identification and analysis of environmental and land-use variables significantly related to regeneration. Juniper woodlands in this part of Spain generally show a remarkable level of regeneration, although some significant differences were detected between the two existing populations. Of the factors studied, time since regeneration started, elevation, and soil rock surface cover influence J. oxycedrus regeneration at most of the individual classes considered, indicating the significance of these variables in this species regeneration. Canopy cover and depth of the organic layer and zone also affect several of the recruitment classes. Furthermore, radiation, the time elapsed since regeneration started, elevation, and aspect affect stand structure to a significant extent. The results of this study enlarge the knowledge on J. oxycedrus regeneration and woodland structure, providing helpful information for the conservation of these protected habitats. [ABSTRACT FROM AUTHOR]

Dioecy is a mating system in which a greater reproductive effort has been observed in one sex than the other. This is expressed in differences between the sexes in growth rate and spatial segregation. The spatial structure of Juniperus thurifera subsp. thurifera and Juniperus communis subsp. communis and growth rate of tree-ring width of J. thurifera were tested in different habitat conditions in Santo Domingo de Silos in northern Spain. We analyzed junipers growing on the eastern slope, with better habitat conditions, and the western, with poorer habitat conditions. The studies found that males of J. communis were taller when compared to the females, both on the eastern and the western slope. J. thurifera females were taller on the eastern slope (the better habitat), but shorter on the western slope as compared to males. J. thurifera males and females on the eastern slope had the greater tree-ring width in comparison with those on the western slope. The annual tree-ring width of males dominated over females on both slopes at first, probably from the time of sexual maturation. However, these differences persisted to the end of the analyzed period only on the poorer western slope. The growth rate of females and males after several years was equal on the eastern slope. Spatial segregation has not been shown, probably due to the homogeneity of the habitat on both slopes. Studies have shown that the decrease of growth rate in J. thurifera females can occur only in the poorer habitat conditions. [ABSTRACT FROM AUTHOR]

Because climate can affect xylem cell anatomy, series of intra-annual cell anatomical features have the potential to retrospectively supply seasonal climatic information. In this study, we explored the ability to extract information about water stress conditions from tracheid features of the Mediterranean conifer Juniperus thurifera L. Tracheidograms of four climatic years from two drought-sensitive sites in Spain were compared to evaluate whether it is possible to link intra-annual cell size patterns to seasonal climatic conditions. Results indicated site-specific anatomical adjustment such as smaller and thicker tracheids at the dryer site but also showed a strong climatic imprint on the intra-annual pattern of tracheid size. Site differences in cell size reflected expected structural adjustments against cavitation failures. Differences between intra-annual patterns, however, indicated a response to seasonal changes in water availability whereby cells formed under drought conditions were smaller and thicker, and vice versa. This relationship was more manifest and stable at the dryer site. [ABSTRACT FROM AUTHOR]

Biomass fractions (total aboveground, branches and foliage) were estimated from a small footprint discrete-return LiDAR system in an unmanaged Mediterranean forest in central Spain. Several biomass estimation models based on LiDAR height, intensity or height combined with intensity data were explored. Raw intensity data were normalized to a standard range in order to remove the range dependence of the intensity signal. In general terms, intensity-based models provided more accurate predictions of the biomass fractions. Height models selected were mainly based on a percentile of the height distribution. Intensity models selected included variables that consider the percentage of the intensity accumulated at different height percentiles, which implicitly take into account the height distribution. The general models derived considering all species together were based on height combined with intensity data. These models yielded R 2 values greater than 0.58 for the different biomass fractions considered and RMSE values of 28.89, 18.28 and 1.51Mgha− 1 for aboveground, branch and foliage biomass, respectively. Results greatly improved for species-specific models using the main species present in each plot, with R 2 values greater than 0.85, 0.70 and 0.90 for black pine, Spanish juniper and Holm oak, respectively, and with lower RMSE for the biomass fractions. Reductions in LiDAR point density had only a small effect on the results obtained, except for those models based on a variation of the Canopy Reflection Sum, which was weighted by the mean point density. Based on the species-specific equations derived, Holm oak dominated plots showed the highest average carbon contained by aboveground biomass and branch biomass 44.66 and 31.42Mgha−1 respectively, while for foliage biomass carbon, Spanish juniper showed the highest average value (3.04Mgha−1). [Copyright &y& Elsevier]

Cupressus sempervirens L., Juniperus communis L. and Cistus ladanifer L. are Mediterranean arboreal and shrub species that possess essential oils (EO) in their leaves and branches. This study aimed at characterizing the EOs obtained by steam distillation from the three species collected in different locations from Spain (Almazán, Andévalo, Barriomartín, Cerezal, Ermitas and Huéscar). For this purpose, volatiles composition was determined by GC-MS, and different bioactivities were evaluated. The highest content in terpenes was observed in C. sempervirens (Huéscar origin) followed by J. communis (Almazán origin), corresponding to 92% and 91.9% of total compounds, respectively. With exception of C. ladanifer from Cerezal that presented viridiflorol as the most abundant compound, all the three species presented in common the α-pinene as the major compound. The EOs from C. ladanifer showed high antibacterial potential, presenting MIC values from 0.3 to 1.25 mg/mL. Concerning other bioactivities, C. ladanifer EO revealed an oxidation inhibition of 83%, while J. communis showed cytotoxicity in the MCF-7 cell line, and C. sempervirens and C. ladanifer EOs exhibited the highest potential on NCI-H460 cell lines. Nevertheless, some EOs revealed toxicity against non-tumoral cells but generally presented a GI50 value higher than that of the tumor cell lines. [ABSTRACT FROM AUTHOR]

• Intra-annual growth patterns differ between cold and dry sites. • Growth bimodality is typical for the dry continental site. • Growth bimodality is the response to autumn soil moisture availability. • Growth at the cold site exhibits a right-skewed unimodal distribution. • High spring growth rates can compensate for growth cessation during dry summers. Mediterranean trees and shrubs adjust physiological processes to ensure their functioning under shifting dry conditions. However, little is known about spatial and between-species differences in cambial dynamics and how their temporal variability determines climatic adaptability. We used the Vaganov‒Shashkin process-based model to simulate five decades of daily cambial dynamics of coexisting junipers (shrubs/short-stature trees) and pines (tall trees) at two climatically contrasting continental sites in northeastern Spain. We hypothesized that different sites and growth forms may shift from unimodal to bimodal growth patterns, which in turn determines their ability to cope with climate stress. The model produced simulations coherent with ring-width chronologies, xylogenesis data and field monitoring of soil moisture. The model successfully captured differences in growth patterns between sites, but it was unable to highlight differences between coexisting species. The cambial dynamics of all the species were controlled by soil moisture in summer, resulting in bimodal or right-skewed unimodal growth patterns. Simulated cambial dynamics were strongly bimodal, with two distinct peaks in spring and autumn and frequent growth cessation during summer at the dry site with Juniperus thurifera and Pinus halepensis. The growth dynamics of both species at the cold site (Juniperus communis, Pinus uncinata) were rather right-skewed unimodal, suggesting reduced but continuous summer cambial activity. Species at the cold site responded to increasing moisture limitation over the last decades by earlier onset of cambial activity and increased spring cambial kinetics. The shifting of spring growth phenology and kinetics was less effective at the dry site, where both species reduced their growth during summer significantly. Our results suggest that growth adaptability on intra-annual scale determines the performance of woody plants under ongoing climate change in drought-prone regions. High responsiveness of cambial activity corroborates other physiological adaptations which jointly determine the climate-change resistance of junipers and pines. [ABSTRACT FROM AUTHOR]

Abstract: In order to understand the effects of changes in traditional forest management on Spanish juniper (Juniperus thurifera L.) forest dynamics, height and radial growth patterns were studied in 107 juniper trees in Cabrejas del Pinar (Soria, Central Spain). Suppressions in height and radial growth were common until the second half of XIXth century. These suppressions occurred at relatively low tree heights, and affected 30% of the sampled trees. The individual suppressions ended abruptly with a sharp increase in height and radial growth. These results fit well into the browsing cessation model, suggesting that an intense browsing pressure shaped this forest. The timing in the reduction of the browsing pressure matches the regional decrease in transhumant livestock that occurred in Spain during the second half of XIXth century. No difference in height-growth rate between suppressed and non-suppressed trees was observed for post-suppression period, indicating a high recovery capacity for J. thurifera. We observed a high variability in height-growth rate during post-suppression periods. This variability was poorly related to site factors (competition, landform), being related to tree life (age and presence of past suppression events). Traditional logging based solely on trees morphological traits may be partially responsible of this pattern. [Copyright &y& Elsevier]

Woodlands of the Mediterranean species Juniperus oxycedrus ssp. macrocarpa (maritime juniper)are both vulnerable and ecologically important. Their ecology and biological status along the SW coast of Spain are not well known; this, the first major study of these juniper populations is a basis for future research and restoration policies. These communities are subject to harsh conditions, the plant composition being controlled by several factors at different scales. On a large scale, climate and soil texture play an important role in controlling the soil water availability to plants, and in separating xerophytic from mesic communities. On a small scale, coastal physiography, and substrate composition are related to differences in the floristic composition. Coastal plantations modify environmental conditions, such as sand mobility and salt spray deposition, inducing important changes in plant communities. The population of maritime juniper on this coast was estimated in ca. 25 000 individuals, of which 93.6% are concentrated in three locations. Large proportions of young individuals were found in extensive and protected populations. However, adult individuals dominated the smaller populations located under pine plantations. This limitation of recruitment may be imposed by several factors. A male biased ratio was detected on the southern coast of Cádiz, which I hypothesize is due to the lower cost of pollen production in a stressful habitat. Preservation of suitable habitats, the recovery of abandoned pine plantations, and the connection between juniper populations, seem to be important requisites for the conservation of maritime juniper in the southwestern coast of Spain. [ABSTRACT FROM AUTHOR]

Leaf and (unripe and ripe) berry essential oils of Juniperus oxycedrus ssp. badia (H. Gay) Debeaux grown wild in Spain have been analysed by capillary GC and GC-MS in combination with retention indices. A seasonal investigation of both leaf and berry oils was also performed. Among the approximately 80 constituents investigated (representing 90–98% of the oils) 60–68 were identified (80–97% of the oil composition). The leaf oils were mainly composed of α-pinene (40–57%) and manoyl oxide (5–10%). The (unripe) berry oils were dominated by α-pinene (65%) with moderate amounts of myrcene, limonene, germacrene D or γ-muurolene. Several differences in yields and chemical composition from a qualitative and quantitative point of view were detected when comparing all the oil samples analysed. In addition, two oil samples were examined, but found inactive, against the replication of HIV-1(IIIB) and HIV-2(ROD) in cell culture, whereas the samples were toxic for the cells at a 50% cytotoxic concentration of 106 and 123 μg/ml, respectively. [Copyright &y& Elsevier]

One of the most important anthropic disturbances on Mediterranean coastal dunes is the plantation of pine trees. However, the impact of coastal pine plantations on environmental gradients and on the spatial zonation of vegetation has received little attention. I analysed the spatial pattern of vegetation along sea-inland gradients from the foredune inland in three dune systems at the Gulf of Cádiz (SW Spain) to assess the effects of pine plantations on both the environment and the plant communities. In this study, I focus on the effects of the "Wooded dunes with Pinus pinea and/or Pinus pinaster " European habitat (code 2270) on the "Coastal dunes with Juniperus spp." European habitat (code 2250), both considered as priority habitat, and which in many cases compete for the same range of the spatial zonation of vegetation. CCA showed that the distance to the shoreline was the main factor controlling the composition of sand dune communities, even when several environmental gradients were modified by the presence of pine trees. Boundary Analysis detected several stretches with a characteristic vegetation that correspond to dune geomorphological zones. However, the plantation of pine trees on coastal dune ridges modified salt spray deposition and sand mobility landward, the main factors causing vegetation zonation in coastal dunes, making characteristic species of semifixed habitats such as Armeria pungens and Artemisia chritmifolia disappear. Pine plantations also shade and reduce wind flow producing negative effects on the growth and reproduction of the heliophilous and dioecious wind-pollinated Juniperus macrocarpa. Therefore, Pinus pinea may be considered as a physical ecosystem engineer in coastal sand dunes in spite of not being a species well adapted to salt spray and sand mobility, in contrast to J. macrocarpa. A better understanding of the ecological and geomorphological coastal processes is needed in order to promote better management and restoration actions of the coastal dune habitats to preserve the rich and specialized flora that inhabits these ecosystems, including Juniperus macrocarpa. Image 1 • Juniperus macrocarpa is a specialized species inhabiting coastal dunes. • Coastal pine plantations modify salt spray, sand mobility and vegetation zonation. • Coastal pine plantations have detrimental effects on maritime juniper communities. • Pinus pinea may be considered as a physical ecosystem engineer in coastal sand dunes. • Better understanding of the ecological and geomorphological coastal processes is needed. [ABSTRACT FROM AUTHOR]

Background and Objectives—Coexisting tree and shrub species will have to withstand more arid conditions as temperatures keep rising in the Mediterranean Basin. However, we still lack reliable assessments on how climate and drought affect the radial growth of tree and shrub species at intra- and interannual time scales under semi-arid Mediterranean conditions. Materials and Methods—We investigated the growth responses to climate of four co-occurring gymnosperms inhabiting semi-arid Mediterranean sites in northeastern Spain: two tree species (Aleppo pine, Pinus halepensis Mill.; Spanish juniper, Juniperus thurifera L.) and two shrubs (Phoenicean juniper, Juniperus phoenicea L.; Ephedra nebrodensis Tineo ex Guss.). First, we quantified the intra-annual radial-growth rates of the four species by periodically sampling wood samples during one growing season. Second, we quantified the climate–growth relationships at an interannual scale at two sites with different soil water availability by using dendrochronology. Third, we simulated growth responses to temperature and soil moisture using the forward, process-based Vaganov‒Shashkin (VS-Lite) growth model to disentangle the main climatic drivers of growth. Results—The growth of all species peaked in spring to early summer (May–June). The pine and junipers grew after the dry summer, i.e., they showed a bimodal growth pattern. Prior wet winter conditions leading to high soil moisture before cambium reactivation in spring enhanced the growth of P. halepensis at dry sites, whereas the growth of both junipers and Ephedra depended more on high spring–summer soil moisture. The VS-Lite model identified these different influences of soil moisture on growth in tree and shrub species. Conclusions—Our approach (i) revealed contrasting growth dynamics of co-existing tree and shrub species under semi-arid Mediterranean conditions and (ii) provided novel insights on different responses as a function of growth habits in similar drought-prone regions. [ABSTRACT FROM AUTHOR]

Background: Gene flow and polyploidy have been found to be important in Juniperus evolution. However, little evidence has been published elucidating the association of both phenomena in juniper taxa in the wild. Two main areas were studied in Spain (Eastern Iberian Range and Sierra de Baza) with both diploid and tetraploid taxa present in sympatry. Gene flow and ploidy level were assessed for these taxa and the resulted offspring. Results: Twenty-two allo-triploid hybrids between J. sabina var. sabina and J. thurifera were found in the Eastern Iberian Range population. However, in the Sierra de Baza population no triploids were found. Instead, 18 allo-tetraploid hybrids between two tetraploid taxa: J. sabina var. balkanensis and J. thurifera were discovered. High genetic diversity was exhibited among the tetraploid hybrids at Sierra de Baza, in contrast to the genetically identical triploid hybrids at the Eastern Iberian Range; this suggests meiotic difficulties within the triploid hybrids. In addition, unidirectional gene flow was observed in both studied areas. Conclusion: Polyploidy and hybridization can be complementary partners in the evolution of Juniperus taxa in sympatric occurrences. Juniperus was shown to be an ideal coniferous model to study these two phenomena, independently or in concert. [ABSTRACT FROM AUTHOR]

• Junipers shrub dieback and mortality triggered by drought are understudied. • We compared growth and isotopes of living vs. dead junipers in two different sites. • Growth and isotopes showed site-specific patterns in living and dead junipers. • Growth was constrained by warm-dry summer conditions enhancing evapotranspiration. • Growth statistics were not robust early-warning signals of impending shrub death. Drought-induced dieback episodes are globally reported among forest ecosystems but they have been understudied in scrublands. Chronically-stressed individuals are supposed to be more vulnerable prior to drought which triggers death. We analyzed drought-triggered dieback and mortality events affecting Mediterranean Juniperus phoenicea scrublands in two sites with contrasting climate and soil conditions located in Spain. We characterized the radial growth patterns of coexisting living and dead junipers, including the calculation of growth statistics used as early-warning signals, quantified growth response to climate, and analyzed the wood C and O isotope discrimination. In the inland, continental site with rocky substrates (Yaso), dead junipers grew less than living junipers about three decades prior to the dieback started in 2016. However, in the coastal, mild site with sandy soils (Doñana), dead junipers were smaller but grew more than living junipers about two decades before the dieback onset in 2005. The only common patterns between sites were the higher growth coherence in both living and dead junipers prior to the dieback, and the decrease in growth persistence of dead junipers. Cool and wet conditions in the prior winter and current spring, and cool summer conditions enhanced juniper growth. In Doñana, growth of living individuals was more reduced by warm July conditions than in the case of dead individuals. Higher δ13C values in Yaso indicate also more pronounced drought stress. In Yaso, dead junipers presented lower δ18O values, but the opposite occurred in Doñana suggesting different changes in stomatal conductance prior to death. Warm summer conditions enhance evapotranspiration rates and trigger dieback in this shallow-rooted species, particularly in sites with a poor water-holding capacity. Chronic, slow growth is not always a reliable predictor of drought-triggered mortality. [ABSTRACT FROM AUTHOR]

This paper reviews the past distribution of Aleppo pine woodlands in the Ebro Basin, Northeastern Iberia, from the Mesolithic to Modern times based on wood charcoal data. The aim is to detail the chronological timing and the drivers explaining the long-term presence of Aleppo pine woodlands and associated thermophilous flora. The available charcoal data support the early spread of Pinus halepensis during the Mesolithic (ca. 9000 cal BP) accompanied by Mediterranean trees and shrubs like Quercus sp. evergreen, Juniperus sp., Arbutus unedo, Pistacia lentiscus, Rhamnus/Phillyrea , Cistaceae, and Rosmarinus officinalis , as a local response to global climate change in the Early Holocene. During the arrival and the propagation of the Neolithic culture (ca. 7500–5500 cal BP), anthracological records, as well as regional palynological sequences, demonstrate the progressive replacement of an conifer-dominated open parkland by both Quercus sp. deciduous and evergreen woodlands in response to the Middle Holocene rise in temperature and humidity. This evidence, however, converges with the general idea that the presence and the spread of Pinus halepensis and associated scrubland have usually been attributed to the onset of landscape anthropization. The frequency of xero-thermophilous open scrubland and the use of Aleppo pine for fuel and woodcrafting progressively increased during the Bronze and Iron Ages, and especially in Ibero-Roman and Medieval/Islamic times, when the vegetation landscape in the Middle Ebro Basin was largely deforested as a consequence of increasing demographic pressure, grazing and the establishment of proto-urban centers. • We review the past distribution of Pinus halepensis in the Ebro Basin (NE Iberia) based on anthracological records. • Wood charcoal data support the early spread of Pinus halepensis during the Mesolithic. • The xero-thermophilous open scrubland and the use of Pinus halepensis as woodcrafting is attested during Metal Ages and historic times. [ABSTRACT FROM AUTHOR]

The steam distilled oil obtained from the berries of Juniperus macrocarpa gathered in the fossil sand dunes of Huelva, southwest Spain, was analyzed by GC and GC/MS in combination with retention indices. The oil contained α-pinene (59.8-70.5%) and myrcene (14.8-15.2%) as major constituents and moderate amounts of γ-muurolene (2.5-5.5%). In addition to these components, minor amounts of β-pinene (2.5-3.4%), limonene (1.1-1.3%), terpinolene (0.9-1.4%), β-caryophyllene (0.4-0.7%), γ-cadinene (0.1-1.1%), δ-cadinene (0.4-1.0%) and α-cadinol (0.2-0.4%) and lower quantities of diterpenes were also identified. [ABSTRACT FROM AUTHOR]