Juniperus Thurifera Research Articles

Analgesic and anti-inflammatory activity of podophyllotoxin derivatives

Context: Podophyllotoxin is a natural product that inhibits the polymerization of tubulin and has served as a prototype for the development of diverse antitumor agents in clinical use, such as etoposide, teniposide and etopophos. Reumacon, another semisynthetic derivative, reached its clinical phase for the treatment of rheumatoid arthritis.Objective: This study investigated the analgesic and anti-inflammatory properties of three compound derivatives from podophyllotoxin.Materials and methods: During a phytochemical study performed on Juniperus thurifera Linne (Cupressaceae) leaves, among other products, several cyclolignans, such as podophyllotoxin, deoxypodophyllotoxin, deoxypicropodophyllotoxin and thuriferic acid were isolated. These compounds, obtained afterwards through semisynthesis, were assayed as analgesic and anti-inflammatory agents. Additionally, the cytotoxic activity of thuriferic acid was evaluated in three cancer cell lines, P-388, A-549 and HT-29, and these data were compared with previous cytotoxicity results obtained for the other three compounds.Results: Analgesic activity results showed that deoxypicropodophyllin is as effective as deoxypodophyllotoxin to inhibit nociceptive perception induced by acetic acid in mice (77.8% ± 4.1% and 71.3% ± 6.5%, respectively), while its cytotoxicity [1.01 × 10−7 (GI50 M)] is 100-fold less. Other set of experiments showed that thuriferic acid, a derivative of podophyllotoxin a thousand times less citotoxic [1.21 × 10−5 (GI50 M)] than deoxypodophyllotoxin, caused significant inhibition of paw edema development in the carrageenan-induced inflammation test (63.4% ± 3.3%), effect comparable to those of deoxypodophyllotoxin (66.3% ± 4.4%), and the standard drug indomethacin (61.5% ± 2.5%).Conclusion: We conclude that deoxypicropodophyllotoxin and thuriferic acid are effective in reducing edema formation. However, deoxypicropodophyllin is more related with analgesic activity than anti-inflammatory effect.

New star on the stage: amount of ray parenchyma in tree rings shows a link to climate

Tree-ring anatomy reflects the year-by-year impact of environmental factors on tree growth. Up to now, research in this field has mainly focused on the hydraulic architecture, with ray parenchyma neglected despite the growing recognition of its relevance for xylem function. Our aim was to address this gap by exploring the potential of the annual patterns of xylem parenchyma as a climate proxy. We constructed ring-width and ray-parenchyma chronologies from 1965 to 2004 for 20 Juniperus thurifera trees growing in a Mediterranean continental climate. Chronologies were related to climate records by means of correlation, multiple regression and partial correlation analyses. Ray parenchyma responded to climatic conditions at critical stages during the xylogenetic process; namely, at the end of the previous year's xylogenesis (October) and at the onset of earlywood (May) and latewood formation (August). Ray parenchyma-based chronologies have potential to complement ring-width chronologies as a tool for climate reconstructions. Furthermore, medium- and low-frequency signals in the variation of ray parenchyma may improve our understanding of how trees respond to environmental fluctuations and to global change.

Chemical composition and antibacterial activities of the essential oils isolated from Juniperus thurifera L. var. Africana

This study describes the chemical composition and antibacterial activities of essential oils of Moroccan Juniperus thurifera L. var. Africana (Cupressaceae). The essential oil of dried leaves was isolated by hydrodistillation, vapohydrodistillation and microwaves. Sixty-four compounds in J. thurifera L. var. Africana oils were identified (79.9%, 92.4% and 98.4% of the oil, respectively). The most abundant compound in J. thurifera L. var. Africana oils is sabinene (38%, 36.2% and 39.4%). Antibacterial activities of J. thurifera essential oils was tested against bacteria Gram ( − ) and Gram (+). The oil is very active against all bacteria tested except Pseudomonas, which turned out to be very resistant.

Elimination of cone and seed pests by wildfire opened a five-year regeneration window in a non-regenerating incense-juniper (Juniperus thurifera L.) stand

Abstract The sanitary status of seed cones of incense juniper, Juniperus thurifera, has been surveyed from 2001 to 2011 in a relict population of the French Pyrenees (Rié Mountain, Haute-Garonne, France) which has been severely affected by a wildfire during the summer 2003. Damage to seed and cones was compared on the same trees before and following the 2003 fire. Before the fire, natural regeneration was severely hindered by the joint damage of a seed mite, Trisetacus quadrisetus, and a seed chalcid, Megastigmus thuriferana which limited to 25-55 the number of sounds seeds falling on the ground per tree. The fire destroyed a large part of the stand but simultaneously killed most of insect seed predators. No flowering was observed the following year (2004), thus contributing to eliminate the remaining predators. In spite of large annual fluctuations, more than 200 sound seeds were dispersed on the average per tree in 2006 and 2009, i. e. 4-10 times more than before the fire. Seed chalcids and mites only began to recolonize the stand during summer 2008, probably originating from nearby stands of J. thurifera (chalcids) or J. communis (mites). Although the pest populations regularly increased every year, cone damage remains concentrated on less than ten trees. Unexpected events such as wildfires may thus play a regulating role upon seed predation by arthropods and opened a regeneration window of five years at least, as it can be observed from the sudden appearance of numerous seedlings during this period.

Le Genévrier thurifère, vieil arbre compagnon de l’homme en Méditerranée occidentale

Abstract Being a heliophilous species, Juniperus thurifera L. profited and colonized the open environment coming from the Tertiary and Quaternay climatic changes. Widespread over continental territories, mainly on limestone, between 200 and 3150 m a. s. l., it shows a fragmented area (N-Africa, Iberian Peninsula, Pyrénées, SE Alpes and Corsica). Biogeographically, it’s also defining ‘ relictic’ communities. Suffering along the times accidental fires, wild herbivours pressure, parasitic and symbiotic plant and animal, this tree was “ pre-adapted” to the human exploitation. Resistant to prune – in many cases a pollard tree – and to the action of herds, it constituted a toponymical reference, harbor, a hunting area, offered firewood and timber very resistant to the open air, medicinal products, pasture and cultivated lands, plants for bees, etc. Along centuries, the result was an agro-silvo-pastoral landscape which supported an autarchic or transhumant system. Moreover, old cultural regulations assured their stability. Nevertheless, until the 60’ s of the XXth century, the J. thurifera populations were more or less intensively cleared or destroyed. Fortunately enough, after this moment, these forests began to recover and increased their density, especially in Spain. First because of the rural abandonment, after because of the forest services interventions and finally due to the scientific and conservation policies we can contemplate a general protection of these special tree communities, mainly in Europe. It’s true that along the last times many works on its biology and ecology were carried out and published, but in this speech I would like to present some data and reflections on the gaps of knowledge around the incense juniper.

Typification de Juniperus thurifera var. africana Maire, délimitation taxonomique et conséquences nomenclaturales sur le Genévrier thurifère d’Algérie

Abstract Spanish juniper populations of the Moroccan Atlas, very studied, are known to be distinct from European populations which justified creation of the taxon Juniperus thurifera var. africana Maire, often treated at subspecies rank. The Algerian populations from Aures mountain, in turn, have recently been reconciled with European populations on the basis of their genetic polymorphism (AFLP), which makes us question the taxonomic and nomenclatural status this biogeographical entity. A nomenclatural analysis was performed on all taxa associated with Juniperus thurifera. It showed that the René Maire’s var. africana includes heterogeneous collections from both Morocco and Algeria. One of the herbarium sheets from Algeria, recently designated as lectotypus, is unfortunately disabled, which is why we have designated another, collected from Morocco in order to conserve the dominant use. A taxonomic synthesis, completed by a brief morphological study of fruits based on herbarium samples, con- cludes with the desirable distinction of a Moroccan taxon (var. or subsp. africana) and an Algerian one, which has thus no name. We call it here Juniperus thurifera var. aurasiaca and a MPU herbarium sheet collected in Algeria by René Maire is designated as holotypus.

Le Genévrier thurifère (Juniperus thurifera L.) dans les Aurès, Algérie : considérations générales, cartographie, écologie et groupements végétaux

Abstract The present contribution focus on the thuriferous Juniper (Juniperus thurifera L.) in the Aurès region (Eastern of Algeria) Algeria. It results from the synthesis of different approaches such as cartography, floristic diversity, and ecology concerning various localities. Structure and physiognomy parameters revealed a frequent multi-stemmed architecture with a conical morphotype when branches were protected from damages. The correspondences analysis highlighted two gradients : physiognomy and altitude. However, associated plants could be discriminated in four plant communities whose determinism is closely related to anthropogenic action. A further analysis of the biological spec- trum confirms these results : therophytisation was more intense at low altitude. Given the magnitude of anthropogenic threats faced by forest formations of the Aurès, especially those of Juniperus thurifera, it’s time to quickly implement a more efficient conservation and sustainable development policy for protecting this threatened tree.

Environmental heterogeneity and neighbourhood interference modulate the individual response of Juniperus thurifera tree-ring growth to climate

Individual variation of tree-ring growth response to climate and heterogeneity of the local environment are usually neglected in dendrochronological research. Even if there is evidence showing that individual responsiveness to climate may depend on intrinsic traits such as tree age, size or sex, its modulation by the local heterogeneity of extrinsic factors has been less studied. Using an extensive, strictly regular sampling scheme across a 3300ha woodland, we assessed the individual variation of tree-ring growth responses to climate in 100 Juniperus thurifera L. trees. The climatic response was evaluated by bootstrapped correlations of both population- and individual-based tree-ring chronologies with monthly records of precipitation, cloudiness, minimum and maximum temperatures. We studied also the influence of extrinsic abiotic (elevation, slope, heat load, tree location) and biotic (competition from neighbouring trees) factors on the individual growth variation and its climatic response. At a population level, growth was controlled by February–March precipitation, April minimum temperature, and June water stress. A significant proportion of individuals did not respond to those variables, but were sensitive to others not relevant at the population level. Inter-annual growth variation was strongly modulated by competition, whereas trees under lower competition levels, in eastern and warmer areas, were the most responsive to climate. The individual climatic response was, at least partially, modulated by the local heterogeneity of extrinsic factors. By considering environmental heterogeneity and neighbourhood interference we can identify the spectrum of site-dependent climatic responses in a population, which in turn will enable more realistic predictions of tree responses to ongoing climate change.

Effect of age and planting site on survival and growth of seedlings of Juniperus thurifera L.

L’objectif de cette étude était de comparer la survie et la croissance des plants de Juniperus thurifera d’une saison de croissance cultivés dans des conteneurs de deux capacités (200 ml et 300 ml) à des plants de deux saisons de croissance cultivés dans une seule taille de conteneur (300 ml). Les plants ont été cultivés en 2006 et 2007 à partir du même lot de semences et suivant le même schéma annuel de fertilisation. Ainsi une dose de 135,05 mg de N a été appliquée pour les plants d’un an et une dose de 271 mg de N pour les plants de deux ans. Les plants ont été transplantés en février 2008 dans deux sites localisés à Monreal del Campo (Teruel) et Buenhache de la Sierra (Cuenca) pour étudier leur survie et leur développement. La survie au cours de la première année était de 100 % dans tous les traitements à Monreal del Campo, tandis qu’à Buenhache la mortalité des plants d’un an cultivés dans des conteneurs de 300 ml a été significativement plus élevée que dans les deux autres traitements. Le choix du site de plantation et du type de culture des plants influence donc la réussite du reboisement.

Acariens et insectes ravageurs de deux cupressacées menacées au Maroc : le Genévrier thurifère et le cyprès de l’Atlas

Actuellement, les écosystèmes des deux cupressacées forestières menacés au Maroc, le Genévrier thurifère et le cyprès de l’Atlas, sont très perturbés : sous-bois presque absent, sol érodé, et régénération très réduite. S’y ajoute l’impact des ravageurs (acariens et insectes), spécialisés dans l’exploitation des galbules ou des cônes et des graines, sur la production de graines susceptibles de germer. Cet impact des ravageurs diminue de manière notable le nombre de graines susceptibles de donner naissance à des plantules. La présente étude a pour but de : 1) établir l’inventaire de la faune entomologique liée aux galbules/cônes et aux graines de ces deux conifères, 2) mesurer son impact sur les potentialités de régénération, 3) préciser les relations phénologiques entre ces ravageurs et leur plante hôte. Pour cela, on a choisi plusieurs sites dans l’aire naturelle marocaine des deux cupressacées. Pour le Thurifère, les sites choisis incluaient plusieurs espèces de Juniperus afin de pouvoir préciser si des espèces de ravageurs pouvaient passer de l’une à l’autre, et quelles étaient les différences éventuelles entre les populations de ravageurs présentes sur chaque essence. Pour le cyprès de l’Atlas, on s’est également efforcé de collecter des cônes de l’espèce voisine introduite, le cyprès toujours vert, afin de surveiller les échanges de faune possibles entre ces essences. Sur chacun des sites, des récoltes des cônes/ galbules ont été effectuées fin mai. Le pourcentage de cônes/ galbules attaqués par les insectes et acariens a été estimé, puis les graines ont été extraites pour être radiographiées afin d’estimer le potentiel de graines viables. Une étude plus précise a été menée sur les punaises du genre Orsillus, afin de comparer leur réponse vis-à-vis des deux espèces de cyprès.

Colonization of abandoned land by Juniperus thurifera is mediated by the interaction of a diverse dispersal assemblage and environmental heterogeneity.

Land abandonment is one of the most powerful global change drivers in developed countries where recent rural exodus has been the norm. Abandonment of traditional land use practices has permitted the colonization of these areas by shrub and tree species. For fleshy fruited species the colonization of new areas is determined by the dispersal assemblage composition and abundance. In this study we showed how the relative contribution to the dispersal process by each animal species is modulated by the environmental heterogeneity and ecosystem structure. This complex interaction caused differential patterns on the seed dispersal in both, landscape patches in which the process of colonization is acting nowadays and mature woodlands of Juniperus thurifera, a relict tree distributed in the western Mediterranean Basin. Thrushes (Turdus spp) and carnivores (red fox and stone marten) dispersed a high amount of seeds while rabbits and sheeps only a tiny fraction. Thrushes dispersed a significant amount of seeds in new colonization areas, however they were limited by the presence of high perches with big crop size. While carnivores dispersed seeds to all studied habitats, even in those patches where no trees of J. thurifera were present, turning out to be critical for primary colonization. The presence of Pinus and Quercus was related to a reduced consumption of J. thurifera seeds while the presence of fleshy fruited shrubs was related with higher content of J. thurifera seeds in dispersers’ faeces. Therefore environmental heterogeneity and ecosystem structure had a great influence on dispersers feeding behaviour, and should be considered in order to accurately describe the role of seed dispersal in ecological process, such as regeneration and colonization. J. thurifera expansion is not seed limited thanks to its diverse dispersal community, hence the conservation of all dispersers in an ecosystem enhance ecosystems services and resilience.

Effects of woodland maturity, vegetation cover and season on enzymatic and microbial activity in thermophilic Spanish Juniper woodlands (Juniperus thurifera L.) of southern Spain

There are still considerable uncertainties about soil functioning in semi‐arid Mediterranean ecosystems. Hence, studies that have focused on Juniperus species in thermophilic Mediterranean woodlands are practically non‐existent. This study provides a survey of the effects of (i) woodland maturity (mature and young woodlands), (ii) vegetation cover (Juniperus thurifera L. trees, Rosmarinus officinalis L. shrubs and semi‐wooded grasslands) and (iii) growing season (spring, summer and autumn) on soil enzymatic activity (urease, alkaline phosphatase and β‐glucosidase) and microbiological characteristics (microbial biomass C (MBC), basal respiration (Br), and microbial and metabolic quotients) in thermophilic Spanish Juniper woodlands. The results showed that mature woodland maintained a greater enzymatic and microbiological activity than the more productive young woodland. The advanced communities of Juniperus trees and Rosmarinus shrubs exhibited greater enzymatic and microbial activity than grassland areas. Soil biological characteristics were strongly affected by the season. Significant β‐glucosidase activity and Br were observed in the summer, as a consequence of the greater organic matter availability for microbes, despite the reduced soil moisture availability. Thus, foliar abscission in trees and shrubs and withering in grasslands seem to control soil biological activity. Hence, we hypothesize that microbial communities that are adapted to drought exist. In contrast, the presence of greater N and P content in summer seems to reduce the urease and phosphatase activities. In addition, the more advanced communities (Juniperus and Rosmarinus covers, especially in mature woodland) showed an inherent trend towards efficiency in C utilization throughout the growing seasons, thus increasing the MBC at the end of the growing season.

A new species and new records of the subgenus Typhlodromus Scheuten from Spain, with a key to the world species (Acari: Phytoseiidae)

A new mite species of the family Phytoseiidae (Acari: Mesostigmata), Typhlodromus (Typhlodromus) thuriferus sp. nov. collected from the Cupressaceae Juniperus thurifera in Spain is described. Three species of the same subgenus, new records for Spain, are also included. A key to all the species of this subgenus is given.

Factors driving growth responses to drought in Mediterranean forests

We lack information regarding the main factors driving growth responses to drought in tree species with different vulnerability against this stressor and considering sites with contrasting climatic conditions. In this paper, we identify the main drivers controlling growth response to a multi-scalar drought index (Standardized Precipitation Index, SPI) in eight tree species (Abies alba, Pinus halepensis, Quercus faginea, Pinus sylvestris, Quercus ilex, Pinus pinea, Pinus nigra, Juniperus thurifera). We sampled forests growing across a pronounced climatic gradient under Mediterranean conditions in north-eastern Spain. To summarize the patterns of growth responses to drought, we used principal component analysis (PCA). To determine the main factors affecting growth responses to drought, correlation and regression analyses were carried out using a set of abiotic (climate, topography, soil type) and biotic (Normalized Difference Vegetation Index, Enhanced Vegetation Index, tree-ring width, diameter at breast height) predictors and the PCs loadings as response variables. The PCA analysis detected two patterns of growth responses to drought corresponding to xeric and mesic sites, respectively. The regression analyses indicated that growth responses to drought in xeric forests were mainly driven by the annual precipitation, while in mesic sites the annual water balance was the most important driver. The management of Mediterranean forests under the forecasted warmer and drier conditions should focus on the main local factors modulating the negative impacts of drought on tree growth in xeric and mesic sites.

Previous Land Use Alters the Effect of Climate Change and Facilitation on Expanding Woodlands of Spanish Juniper

In Mediterranean–continental regions, changes in land use are leading to the expansion of valuable habitats like endemic Juniperus thurifera woodlands, but the impact of reduced rainfall, due to climate change, on this expansion remains uncertain. We assessed the early performance of J. thurifera in different global change scenarios with and without facilitation. Saplings were transplanted in three ecosystems types with different previous land use (woodlands, former agricultural fields, and former livestock pastures), microhabitats (open vs. understory of adult trees) and were subjected to two watering regimens. We characterized the abiotic environment and measured survival, growth and two ecophysiological parameters. Former livestock pastures were the least favorable ecosystem, where the nursing effect was greatest. Former agricultural fields had the highest survival, but were more sensitive than woodlands to water scarcity. Reduced rainfall decreased photochemical efficiency, particularly in the least favorable scenarios, but did not affect survival. Water use efficiency enhanced growth under the canopy, but not in the open, whereas photochemical efficiency enhanced growth and survival more in the open. Facilitation was critical for effective recruitment in the harshest scenarios: former livestock pastures and reduced rainfall. Comparison with previous studies suggests that establishment depends on infrequent wet episodes. In Mediterranean ecosystems, changes in land use and climate change are leading to woodland expansion due to the modulating effect of facilitation of the oncoming adverse drier conditions. Nevertheless, the positive effect of facilitation and the negative impact of aridity on tree recruitment are strongly influenced by previous land-use history.

Enhanced growth of Juniperus thurifera under a warmer climate is explained by a positive carbon gain under cold and drought

Juniperus thurifera L. is an endemic conifer of the western Mediterranean Basin where it is subjected to a severe climatic stress characterized by low winter temperatures and summer drought. Given the trend of increased warming-induced drought stress in this area and the climatic sensitivity of this species, we expect a negative impact of climate change on growth and ecophysiological performance of J. thurifera in the harsh environments where it dominates. To evaluate this, we measured long- and short-term radial growth using dendrochronology, photosynthesis and water-use efficiency in males, females and juveniles in three sites in Central Spain. Climate was monitored and completed with historical records. Mean annual temperature has increased +0.2 °C per decade in the study area, and the main warming trends corresponded to spring (+0.2 °C per decade) and summer (+0.3 °C per decade). Radial growth and maximum photosynthesis peaked in spring and autumn. Positive photosynthetic rates were maintained all year long, albeit at reduced rates in winter and summer. Radial growth was enhanced by wet conditions in the previous autumn and by warm springs and high precipitation in summer of the year of tree-ring formation. Cloud cover during the summer increased growth, while cloudy winters led to impaired carbon gain and reduced growth in the long term. We argue that maintenance of carbon gain under harsh conditions (low winter temperatures and dry summer months) and plastic xylogenesis underlie J. thurifera's ability to profit from changing climatic conditions such as earlier spring onset and erratic summer rainfall. Our results highlight that not only the magnitude but also the sign of the impact of climate change on growth and persistence of Mediterranean trees is species specific.

Does day length affect winter bird distribution? Testing the role of an elusive variable.

Differences in day length may act as a critical factor in bird biology by introducing time constraints in energy acquisition during winter. Thus, differences in day length might operate as a main determinant of bird abundance along latitudinal gradients. This work examines the influence of day length on the abundance of wintering crested tits (Lophophanes cristatus) in 26 localities of Spanish juniper (Juniperus thurifera) dwarf woodlands (average height of 5 m) located along a latitudinal gradient in the Spanish highlands, while controlling for the influence of food availability, minimum night temperature, habitat structure and landscape characteristics. Top regression models in the AIC framework explained 56% of variance in bird numbers. All models incorporated day length as the variable with the highest magnitude effect. Food availability also played an important role, although only the crop of ripe juniper fruits, but not arthropods, positively affected crested tit abundance. Differences in vegetation structure across localities had also a strong positive effect (average tree height and juniper tree density). Geographical variation in night temperature had no influence on crested tit distribution, despite the low winter temperatures reached in these dwarf forests. This paper demonstrates for the first time that winter bird abundance increases with day length after controlling for the effect of other environmental variables. Winter average difference in day length was only 10.5 minutes per day along the 1°47′ latitudinal interval (190 km) included in this study. This amount of time, which reaches 13.5 h accumulated throughout the winter season, appears to be large enough to affect the long-term energy budget of small passerines during winter and to shape the distribution of winter bird abundance under restrictive environmental conditions.

Masting uncoupling: mast seeding does not follow all mast flowering episodes in a dioecious juniper tree

Evolutionary selective forces, like predator satiation and pollination efficiency, are acknowledged to be major causes of masting (the variable, periodic and synchronic production of seeds in a population). However, a number of recent studies indicate that resources might also play an important role on shaping masting patterns. Dioecious masting species offer a privileged framework to study the role of resources on masting variation, since male and female plants often experience different reproductive costs and selective pressures. We followed masting and reproductive investment (RI) of the dioecious tree Juniperus thurifera in two populations along 10 years and studied the different response of males and females to experimentally increased water and nutrient availability in a third population.Juniperus thurifera females invested in reproduction three times more resources than males. Such disparity generated different resource‐use strategies in male and female trees. Tree‐ring growth and water use efficiency (WUE) confirmed that sexes differed in their resource investment temporal pattern, with males using current resources for reproduction and females using resources accumulated during longer periods. Watered and fertilized female trees presented significantly higher flowering reproductive investments than males and experienced an extraordinary mast‐flowering event. However, seeding RI and mast seeding were not affected by the treatment. This suggests that although resource availability affects the reproductive output of this species, there are other major forces regulating masting on J. thurifera.During 10 years, J. thurifera male and female trees presented high and low flowering years more or less synchronously. However, not all mast flowering episodes resulted in mast seeding, leading to masting uncoupling between flowering and seeding. Since flowering costs represent only 1% of females’ total reproductive investments, masting uncoupling could be a beneficial bet‐hedging strategy to maximize reproductive output in spite of unpredictable catastrophic events.

Allometries, biomass stocks and biomass allocation in the thermophilic Spanish juniper woodlands of Southern Spain

The principal objective of this study was to investigate the variations of allometric relationships, biomass stocks and biomass allocation in a Spanish juniper thermophilic community (Juniperus thurifera var. hispanica Mill.) in response to two levels of woodland maturity: mature woodlands, which are situated in shallow stony soils with trees over 140years old and low tree density, and young woodlands, with trees under 100years old growing in deeper soils (generally, abandoned farmland). Branch- and tree-level allometric models were fit from measurements carried out on branches, stems and roots in 42 felled trees. Although age and site are confounded for this juniper community, it is expedient to utilize site-specific equations because the two woodlands showed distinct growth patterns as a result of their very different soil qualities and ages. At the branch level, the relationship was matched for foliage biomass depending on the site. At the tree level, site location significantly affected variables in allometric relationships that were not strictly cumulative (i.e., leaves, branch wood and fine-root biomass). Goodness of fit was improved by including the relative height of the first live whorl (pruning effect) as an additional predictor of crown and coarse root biomass. The young woodland supported more biomass stock across all components due to better soil. Biomass allocation measured in stems, coarse roots and fine roots was significantly higher in the mature woodland, although the young woodland did accumulate more dry mass in the crown. Differences in biomass allocation may be explained by both the age and strategies of J. thurifera to maximize nutrient and water capture for survival in poor soils (site quality effects). Our results also showed that, in mature woodlands, this species accumulates one of the smallest biomass stocks cited for temperate mature conifer stands (7.6Mgha−1) but has a high root to shoot ratio (0.43) as a consequence of growing in poor soil conditions.

Quantitative Tracheid Anatomy Reveals a Complex Environmental Control of Wood Structure in Continental Mediterranean Climate

A detailed understanding of how the climate models the hydraulic system of trees is still lacking, in spite of the need to understand tree response to the ongoing process of climatic change. A systematic correlation of tracheid anatomical features with climate has not been implemented in Mediterranean ecosystems, where climatic change is expected to be particularly intense. We measured ring width and cell number—in addition to intraring position, lumen size, and wall thickness of tracheids—in 10 Juniperus thurifera individuals from north-central Spain. We used this information to perform an exploratory analysis of how these parameters correlated with climatic variables in 1965–2004. Cell number and ring width shared a relatively similar climatic signal, whereas the anatomical variables provided differentiated and diverse signals about climatic conditions during their formation. Earlywood and latewood tracheids differed in controlling factors, with earlywood tracheid size and wall thickness being positively related to rainfall during early summer and latewood tracheid size being positively related to August temperature. Tracheid anatomical variables improved our understanding of climate effects on tree growth and wood formation under harsh environmental conditions, as those experienced in continental Mediterranean climates, where limiting factors show multiple shifts across the year.