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The seasonal patterns of xylem embolism and xylem transport properties in Quercus pubescens Willd. and Quercus ilex L. trees growing in a natural mixed coppice stand in conditions of severe water stress were investigated. Xylem embolism was evaluated in both dehydrating branches and in apical twigs during a whole year. Measurements of xylem water potential were conducted from predawn to sunset on selected sunny days. On the same days, diurnal courses of leaf conductance were monitored. Measurements of half-hourly sap flow were made by the heat-pulse technique throughout the summer. At the onset of summer, a sharp decrease in water potential was observed in both species. Full recovery of water potentials was observed for both species after the first major rainfall event in September. Both experienced serious embolism throughout the year, ranging between minima of c. 60% (expressed as percentage loss of hydraulic conductivity) after the rains in autumn and after bud burst in spring, and maxima of c. 80% during summer and after freezing-thawing events during the winter season. A significant negative linear relationship was found between water potential and xylem embolism in branches dehydrating in air for Q. pubescens and Q. ilex. Q. pubescens had greater efficiency in hydraulic transport (higher specific conductivity and leaf specific conductivity) by the xylem than Q. ilex. In June, leaf conductance was high early in the morning and decreased gradually during the day. Midday depression of leaf conductance, as a result of high evaporative demand combined with water deficit, was observed in both species. In August, leaf conductance of both species was greatly reduced, as water potential dropped to extremely low values, and the stomata were almost completely closed during the afternoon. No hysteresis resulting from plant capacitance was observed in the relationship between shoot water potential and sap flow. Q. pubescens exhibited very high values of whole-tree hydraulic resistance between July and September, whereas Q. ilex generally showed lower values. The effect of soil moisture depletion on the relationship between sap flow and shoot water potential appears as a lowering of water potential at zero flow. A significant decrease of whole-tree hydraulic resistance in both species was observed with the onset of the autumn, preceding the partial recovery of twig hydraulic conductivity. The results demonstrate that both Q. pubescens and Q. ilex, although highly tolerant of severe water stress and tissue dehydration, operate at the limits of safety which are surpassed under severe droughts, and prolonged climatic stress might predispose these Quercus species to decline.

The plant-microorganism combinations may contribute to the success of phytoextraction of heavy metal-polluted soil. The purpose of this study was to investigate the effects of cadmium (Cd) soil concentration on selected physiological parameters of the poplar clone "I-214" inoculated at root level with a strain (BT4) of Pseudomonas fluorescens and a commercial product based on microbial consortia (Micosat F Fito®). Plants were subjected to Cd treatment of 40 mg kg(-1) in greenhouse. The effects of plant-microbe interactions, plant growth, leaf physiology, and microbial activity were periodically monitored. Metal concentration and translocation factors in plant tissues proved enhanced Cd uptake in roots of plants inoculated with P. fluorescens and transfer to shoots in plants inoculated with Micosat F Fito®, suggesting a promising strategy for using microbes in support of Cd uptake. Plant-microbe integration increased total removal of Cd, without interfering with plant growth, while improving the photosynthetic capacity. Two major mechanisms of metal phytoextraction inducted by microbial inoculation may be suggested: improved Cd accumulation in roots inoculated with P. fluorescens, implying phytostabilization prospective and high Cd transfer to shoots of inoculated plants, outlining enhanced metal translocation.

Olive tree (Olea europaea L.) is a drought-tolerant tree species cultivated in Mediterranean-type environments. Although it is tolerant to drought, dry conditions decrease its productivity. A thorough analysis of the hydraulic architecture and wood anatomical plasticity, as well as of their physiological significance, is needed to understand how olive trees will adapt to the predicted increase in frequency and severity of drought in the Mediterranean region. Dendrochronological, stable isotopic (δ13C, δ18O) and wood anatomical analyses were applied to understand how different water availability can affect wood stem structure and function, in rainfed and irrigated at 100 % of crop evapotranspiration (ETc) olive trees in an experimental orchard close to Benevento (Italy) from 1992 to 2009. Dendrochronological data indicate that cross-dating and synchronization of ring-width time series in olive tree is possible. After the start of irrigation, significantly more negative δ13C and lower δ18O values were recorded in irrigated trees indicating higher stomatal conductance and transpiration rates. Increased water balance induced the formation of a higher number of vessels with higher diameter. Water balance variations affected wood anatomy and isotopic composition. Anatomical analyses detected structural and functional adjustments in rainfed trees that produced more vessels with lower diameter to prevent cavitation. Isotopic analyses confirmed that irrigated trees continuously showed enhanced transpiration rates.

Concurrent measurements of sap velocity (heat pulse) and ultrasound acoustic emission were performed on the trunks of mature Turkey oak (Quercus cerris) and sessile oak (Quercus petraea) trees. Plant water status was assessed by measuring leaf water potential, leaf conductance and transpiration. Wood density was estimated non-destructively on the trunk section of the plants by mobile computer tomography, which measures the attenuation of a collimated beam of radiation traversing the trunk in several directions, as the device rotates around the tree. Absorption is proportional to the density of the wood. As wood density is strictly correlated to water content, this non-invasive method allows the water content in the trunk section to be evaluated as well as mapped. Leaf water potential declined each morning until a minimum was reached at midday and recovered in the afternoon, lagging behind changes in transpiration rate. Good correspondence was found between the patterns of sap velocity and cavitation rate. A close correlation was demonstrated between wood density, water content and sap velocity. Sap flow was always higher in Turkey oak than in sessile oak. Trunk signatures by computer tomography appeared to differentiate the two oak species, with the Turkey oak stem clearly more hydrated than the sessile oak ; water storage reservoirs could play an important role in tree survival during extended periods of low soil water availability and in the relative distribution of tree species, especially in the context of global climate change. Late-wood conducting elements of oak species seem to play a significant role in water transport. The mobile computer tomograph was confirmed as a peerless tool for investigating stem water relations. Diurnal variations in the measured parameters under natural drought conditions and the differences between the two oak species are discussed.

Palaeoclimate proxies have demonstrated links between climate changes and volcanic activity. However, not much is known about the impact of volcanic eruptions on forest productivity. Here we used tree-ring width and annually resolved carbon and oxygen isotopic records from tree rings of Araucaria araucana (Molina) K. Koch, providing a centennial-scale reconstruction of tree ecophysiological processes in forest stands nearby the Lonquimay Volcano (Chile). We observed a mean decrease in tree-ring width following the major eruption of 1988-1990 (with aerosol emission), most probably caused by the modified ecological conditions due to acid rain and ash deposition, while a generally negative relationship between δ13C and δ18O would point to a decline in humidity and precipitation. More negative δ13C and lower δ18O values (positive correlation) following the major eruption of 1887-1890 (without aerosol emission) would suggest high stomatal conductance and moisture availability, though tree-ring width (and probably photosynthetic rate) was unaltered. At least for this sample of trees, in the case of eruption with large tephra emission, the beneficial effect of aerosol light scattering on tree productivity appears to be outweighed by the detrimental effect of eruption-induced toxic deposition. Signals of the two major eruptions of the past 200 years at Lonquimay were present in tree rings of nearby A. araucana. No unique response of tree functions to volcanic eruptions can be expected, but rather (1) the variable volcanic properties and (2) the complex interplay of diffuse light increase (aerosol scattering), air temperature decrease (cloud shading), and toxic deposition impact (volcanic ash), makes any prediction of tree growth and ecophysiological response very challenging. © 2012 Springer-Verlag.

Olive tree is a drought tolerant species withstanding prolonged dry periods using physiological and morphological mechanisms of resistance to water stress. In this work we measured functional and yield changes in olive plants (Olea europaea L. ‘Frantoio’ and ‘Leccino’) subjected to different irrigation scheduling. The study was carried out in field trials during the years 2006 and 2007 in a typical hilly olive growing area of southern Italy. Irrigation treatments were applied from pit hardening to fruit veraison and consisted of: a non-irrigated control, a treatment fully irrigated with 100% of maximum crop evapotranspiration (ETc) and two deficit treatments that received 33 and 66% of ETc. Physiological parameters related to plant water status and nitrogen concentration in leaves were determined regularly during the two growing seasons. Vegetative development was monitored measuring the transverse trunk cross-section area, the crown volume, and the dry mass pruned yearly. Yield parameters (dry mass and oil content) were measured on fruits having similar maturity index. Irrigation levels significantly modified plant physiological conditions and vegetative growth of the two cultivars. Significant changes in xylem water potential, stomatal conductance and leaf nitrogen concentration were observed between irrigation treatments, and changes depended on cultivar and time of measurement. Trunk cross-section area, crown volume and pruned wood increased with the amount of water applied. Fruit and oil yield per plant showed a gradual increase with the amount of water supplied to trees, reaching the highest values in plants irrigated with 100% of ETc.

In urban environments, trees are often faced with limiting physical factors at above- and below-ground levels. These factors include poor air quality, and water and soil pollution that may differ substantially from the natural environment. While numerous studies on urban climate and floristic analyses have been published, studies on the physiological performance and growth of trees in urban sites are rather scarce. They are often in contradiction with the general opinion of the growth's constraint. Generally, it is recognized that urban soils are made of poor landfill materials hampering soil water retention. Often, the soil is sealed by asphalted surfaces that prevent rain infiltration. Nevertheless, there is a gap of information to support the hypothesis by which such conditions determine plant water stress. This study will analyze the water relations and the performance of photosynthesis of Quercus ilex exemplars growing in three different conditions of urban green areas (urban park, outskirt/countryside and urban road) in the city of Florence (Italy) conducted in the year 2002. Results have evidenced a decline in photosynthetic rate in all three sites but a certain capacity of Q. ilex to acclimate to the harsh conditions of urban roads in terms of water relations, tissue elasticity and in photosystem efficiency that was higher at the beginning of summer. (c) 2012 Elsevier GmbH. All rights reserved.

In order to identify the distinctive traits of old-growth forests in a Mediterranean context, deadwood occurrence and forest stand structures were investigated in remote forests not subject to anthropogenic disturbance over the past few decades. Five study sites in south-central Italy were selected, and structural parameters were recorded in 1-ha plots. Living trees, deadwood, types, and decay stages were inventoried in the selected sites. Living tree volumes and amounts of deadwood indicated large variability among the investigated forest stands, ranging from 363 to 702 m 3 ·ha -1 for living trees and from 17 to 143 m 3 ·ha -1 for deadwood. Downed deadwood was the most abundant component, due to the natural mortality occurring in the stands. Stumps were the least common among the types of deadwood. All the decay classes were present in each study site. The main structural features useful for characterizing these old-growth forest stands included a multi-sized diameter distribution of living trees, the presence of small-scale gap dynamics, tree height heterogeneity, and high values of living volume and basal area. A ratio of dead to living wood not lower than 10%, downed deadwood much more abundant than standing deadwood, and a large range of deadwood size and decay classes across all the deadwood components are useful traits for tracking old-growth stages in these Mediterranean forests.

Recent attempts to mitigate global change have brought forestry-based carbon (C) sequestration into sharp focus due to its potential to absorb CO2 from the atmosphere. However, the consequences of actual forest management practices on C storage capacity are still controversial to a certain extent. Under such a perspective, a distinctive relevant issue concerns the management of forest ecosystems within areas specifically designated for nature conservation. From the analysis of biomass data from forests in the National Parks of Italy, we found that the average forest C stock and sink per unit area is relatively higher within National Parks (81.21 and 2.18 tons ha71, respectively) than on the overall national territory (76.11 and 1.12 tons ha71 year71, respectively). The analysis confirms the influence of ecological conditions and management approach on C sequestration capacity. Although the results of the proposed assessment approach have to be considered as rough estimates, the trial proves interesting, given the relative lack of specific information, at least on a large scale, about C stocks and sinks within forest areas designated for nature conservation, and the direct comparison with those forest areas not designated to such an end. The C storage capacity can be enhanced by increasing the productivity of forests, minimizing the disturbance to stand structure and composition. Extending conservation strategies adopted in National Parks to other forest areas of the national territory would allow the restoration of C sequestration potential, where unsustainable management practices have degraded relatively large stocks of biomass. L'articolo è disponibile sul sito dell'editore www.tandfonline.com

Context We investigated the relationships between decay classes, morphological characteristics and chemical compounds in Abies alba Mill. and Fagus sylvatica L. stumps in two forest stands in the central Apennines (Italy). The analysis of deadwood decomposition is important in estimating carbon sequestration potential and carbon residence time in forest ecosystems. In addition, deadwood decomposition affects nutrient cycling and microhabitat distribution.

Growth, leaf assimilation rate and leaf water potential of field-grown olive plants were measured over two years after the elimination of the canopy. Canopy height reached 1.43 and 2.12 m by the end of the first and second growing season respectively. Total length of lateral shoots directly inserted on the main axis of each sucker was 11.7 m (average of four plants), whereas that of lateral shoots of the second order (inserted on first order shoots) was 6.36 in by the end of the first growing season. At the end of the first growing season the estimated leaf area per 2 plant was 6.11 m(2). In 1998 leaf assimilation rates, measured three and six months after the elimination of the canopy, were higher than in plants of older age (two- and 10-years-old), but these differences disappeared in 1999. The leaf water potential of plants during the first growing season after coppicing were significantly higher than those of plants that had been cut two, three or 10 years earlier.

Carefully managed tree plantations offer an opportunity for sustainable biomass production. In recent years, the responses of the Salicaceae to environmental constraints have increasingly been investigated at different levels of biological integration, giving rise to a physiological approach to the function of trees in environmental restoration and monitoring. Significant prog-ress has been achieved by the poplar and willow community in understanding targeted characteristics of complex tree stress responses. The Fifth International Poplar Symposium brought together experts in this area, with the main objective being to improve, coordinate and communicate existing national research on the biological and environmental dimension of multifunc -tional poplar and willow plantations. The secondary objective was to develop a network of research scientists and extension workers to provide scientific support for subjects interested in using fast-growing poplar and willow species for tree-related environmental projects. The ultimate goal was to build up services for the multipurpose tree plantation network on local-level management in order to obtain maximized benefits from tree crops. The purpose was also to maximize the synergy between local knowledge and global-level processes that require information on multipurpose tree crop production.

Experiments were carried out to study the effects of N fertilizer rates and timing of application on the yield and grain quality of a rainfed emmer crop ( Triticum dicoccum Shubler) under Mediterranean conditions. The following parameters were analyzed: hulled and net grain yield, hulled index, spikes m −2 , spikelets per spike, kernels m −2 , thousand-kernel weight, biomass, plant height, lodging, grain protein and ash content. In the first experiment, different N rates (30, 60 and 90 kg N ha −1 plus a control not fertilized) were split at three phenological stages (seeding 20%, tillering 40% and stem elongation 40%). In the second experiment, three N doses (30, 60 and 90 kg N ha −1 ) were applied to three crop stages (seeding, tillering and stem elongation). In the third experiment, the rate of 90 kg N ha −1 was distributed in different amounts (90-0-0, 0-90-0, 0-0-90, 45-45-0, 45-0-45, 0-45-45, 30-30-30) at the three mentioned crop stages. Increasing N rates resulted in higher hulled and net grain yield, as well as protein content. Fertilization (from 60 to 90 kg N ha −1 ) applied to tillering maximized hulled and net grain yield. Fertilization (90 kg N ha −1 ) applied to stem elongation gave the highest grain protein content (%) while splitting application (30 kg N ha −1 each) at three phenological stages maximized protein yield per hectare. Application of half or one-third of 90 kg N ha −1 to stem elongation improved grain protein content in comparison with applications at sowing, or at both sowing and tillering. The main factor determining higher yields with increasing N rates in this emmer crop was the number of kernels m −2 . None of the yield components accounted for differences in grain yield when timing and splitting application were varied.

La biomassa di origine agricola e forestale svolgera un ruolo chiave nel raggiungere (2020) gli obiettivi sulle energie rinnovabili. Secondo i Piani di Azione Nazionali le biomasse avranno un particolare ruolo nella produzione di energia termica dove i maggiori investimenti nei mercati domestici e nelle reti di teleriscaldamento sono attesi in Germania, Italia, Gran Bretagna e Svezia. In questo piu ampio contesto, un gruppo di lavoro coordinato dalla Regione Molise ha redatto un piano di analisi territoriale per i vari comparti delle agrienergie (legna, cippato, pellet, biogas e olio vegetale puro) con particolare enfasi alle biomasse di origine forestale. Per ciascun comparto poi e stato redatto un piano di azione che si basa sulla quantita di biomassa disponibile in connessione alle tecnologie di conversione energetica secondo modelli di impiego effettivamente replicabili a scala aziendale e/o interaziendale. I piani di azione tengono conto anche dell’attuale sistema incentivante e del quadro normativo di riferimento e sono stati pensati per un orizzonte temporale di cinque anni. Il Molise e una regione con un forte potenziale nella filiera delle biomasse legnose e dove le nuove tecnologie di conversione energetica (moderne caldaie) sono gia utilizzate cosi come le cippatrici che possono offrire un servizio locale per la produzione di cippato. Il principale contributo delle biomasse legnose e nel mercato dell’energia termica nei piccoli-medi impianti domestici o aziendali e nelle piccole medie reti di teleriscaldamento al servizio di edifici pubblici e privati. Lo studio ha valutato anche il contributo alla riduzione dei gas effetto serra in un’ottica di sostituzione dei combustibili fossili con i combustibili legnosi.

Carefully managed tree plantations offer an opportunity for sustainable biomass production. In recent years, the responses of the Salicaceae to environmental constraints have increasingly been investigated at different levels of biological integration, giving rise to a physiological approach to the function of trees in environmental restoration and monitoring. Significant progress has been achieved by the poplar and willow community in understanding targeted characteristics of complex tree stress responses. The Fifth International Poplar Symposium brought together experts in this area, with the main objective being to improve, coordinate and communicate existing national research on the biological and environmental dimension of multifunctional poplar and willow plantations. The secondary objective was to develop a network of research scientists and extension workers to provide scientific support for subjects interested in using fast-growing poplar and willow species for tree-related environmental projects. The ultimate goal was to build up services for the multipurpose tree plantation network on local-level management in order to obtain maximized benefits from tree crops. The purpose was also to maximize the synergy between local knowledge and global-level processes that require information on multipurpose tree crop production.

Zinc (Zn) is an essential element for plant growth and development, but at high levels this metal can become toxic. Hyperaccumulator species are often not suitable for phytoremediation technologies because they need to be fast growing and have high biomass production, such as those of the Populus genus. Comparative genomics studies of poplars subjected to stress conditions such as heavy metal contamination have generated resources useful for improving the annotation of genes and have provided novel insights in the defense/tolerance mechanisms governing adaptation in non-hyperaccumulator plants. Using a microarray-based comparative analysis, we identified functional gene sets that are differentially regulated in the leaves of Populus × euramericana clone I-214 subjected to an excess but sub-lethal dose of Zn (1 mM). Eco-physiological and chemical analyses confirmed the results obtained in previous similar experiments. A total of 3861 expressed sequence tags (ESTs) were differentially expressed and grouped into two distinct libraries of up-regulated (40%) and down-regulated (60%) putative genes. The annotation of genes and gene products according to the Gene Ontology vocabularies was performed using Blast2GO software. The two transcriptome data sets were used to query all known Kyoto Encyclopedia of Genes and Genomes (KEGG) biosynthetic pathways of the genes identified in this study. The most represented molecular functions and biological processes were nucleotide binding and transcription, transport and response to stress and abiotic and biotic stimuli. The chloroplast, mitochondrion and their membrane systems were the cellular components most affected by excess Zn, as well as the photosynthetic, defense, sulfur and glutathione (GSH) metabolic pathways. The most up-regulated genes encoded electron carriers associated with ferrodoxin, the small subunit of ribulose-bisphosphate carboxylase oxygenase, and enzymes involved in GSH metabolism. This study is the most in-depth transcriptome and gene-annotation analysis of a hybrid poplar to date. The results are presented and critically discussed in terms of poplar response/tolerance to Zn stress for the characterization of non-hyperaccumulator phenotypes and the identification of candidate genes in peren nial plants. These genetic findings provide useful information on tree species’ adaptation to metal stress and provide power ful tools for the selection and/or genetic manipulation of stress-tolerant poplar clones.

A spatially explicit knowledge of forest resources is essential to support the sustainable use of wood as a fuel for producing energy (firewood). This paper describes the integrated use of remotely sensed data and sample based forest inventories to derive a biomass map for coppice forest, resulted estimated potential biomass available is contrasted with local domestic consumptions at the municipality level. The test was carried out in an environmentally and socially homogeneous district of Apennine Mountains (Alto Molise, south-central Italy) coupling multispectral high resolution Landsat 7 ETM+ satellite imagery and a local forest inventory trough the application of the non-parametric estimation procedure k -Nearest Neighbours ( k -NN). Several forest management scenarios were applied in order to evaluate their impact on the potential availability of firewood from coppice forests. The paper introduces data and methods used and presents the achieved results both in terms of the accuracy of the biomass map produced by k -NN and of the relationship between the potential availability and demand for firewood. These results demonstrated that k -NN is able to estimate the biomass of coppice forest in the test area with an accuracy level comparable with recent similar application of k -NN carried out in Boreal regions (RMSE of 25.6%). The application of different forest management scenarios have a significant impact on local estimated firewood balance between potential supply from coppice forests and demand for domestic consumption, depending of the scenarios the net balance changed up to 84%.

The effect of different water availability regimes on several plant water status indicators was studied in order to assess water consumption and drought adaptation in Olea europaea growing in an experimental site plantation in southern Italy (41°06'N, 14°43'E; at an elevation of 250 m a.s.l.). The study was carried out on mature olive plants, (cv. Nocellara del Belice) subjected to different water availability since 1994. Treatments were a rainfed (non-irrigated) and fully irrigated regime (100% of ETc throughout the irrigation season). During the growing season 2007 plants were continuously monitored by automatic point dendrometers measuring stem radius variation. Whole-plant water use was determined using a xylem sap flow method (compensation heat-pulse technique). Additional ecophysiological parameters, such as stomatal conductance and water potential, were as well as vegetative development and biochemical characteristics. Stem Maximum Daily Shrinkage (MDS) and sap flux were also compared. Results were evaluated to investigate water use strategies, functional, and structural acclimation to watering. These observations were analysed to identify valuable parameters that may be used to implement automatic management irrigation practices in olive tree plantations.

Considering that indicators of old-growth features can vary across the European ecoregions, this paper provides some results to identify the distinctive traits of old-growth forests in the Mediterranean ecoregion. Deadwood occurrence as indicator of naturalness is investigated in some remote forest areas that have developed in absence of anthropogenic disturbance over the past few decades. Eleven study sites across the Italian peninsula were elected and records of deadwood were carried out in 1-ha size plots. Deadwood volume, deadwood types and decay stages were inventoried in the selected sites. The amounts of deadwood indicate a large variability among the investigated forest stands: the total volume ranged between 2 and 143 m3ha-1, with an average of 60 m3ha-1. Lying deadwood is the most abundant component of deadwood in the investigated forests, due to the natural mortality occurring in the stands in relation to the processes established in the last decades. On the contrary, stumps are the less represented type of deadwood in almost all the study areas. All the decay classes are present in each study site. The amount of deadwood in Southern Europe, even if lower than that reported for North and Central European countries, could have a different meaning due to the faster decay occurring in Mediterranean forest ecosystems. For this reason, old-growth features and the characteristics of each indicator should be framed and referred to well-defined climatic and biogeographic contexts. Distinctively, under the conditions here investigated, three main deadwood features prove to characterize forest stands close to old-growthness: a ratio of dead to living wood not lower than 10%; lying deadwood much more abundant than the standing one; large range of deadwood size and decay classes across all the deadwood components.

Increasing [CO2] along with associated changes in temperature will most likely alter the structure and function of forest ecosystems and thus will affect their Productivity and their role as stable sinks to CO2 sequestration and as regulators of the global hydrologic cycle. However, models predict that Earth's surface temperatures will increase along with shifts in precipitation that result in greater drought severity and frequency. As an example, maximum summer temperatures are likely to increase more than the average in southern and central Europe, whereas increasing water stress will dramatically affect mainly south-eastern Europe. Thus, forest ecosystems will experience a combination of numerous environmental stresses, which may significantly alter their physiological feedback on regional and continental climate. However, there is a great deal of uncertainty with regard to tree responses to interactive effects of global change scenarios. Models focusing on the interactions between climate change factors might help the scientific community to fill in the gaps in knowledge of how forest trees will respond to interacting effects. However, model accuracy depends to a large extent on our understanding of forest responses to climate changes. We conclude that there is an urgent need for multifactor climate change experimental studies examining the kinetic sensitivity of photosynthesis, stomatal conductance-transpiration, and respiration to the interactive effects of rising temperature, elevated [CO2], and environmental stress, in order to improve our ability to predict the physiological forcing of forest ecosystems on climate change.

The effect of different water availability regimes on several plant water status indicators was studied in order to assess water consumption and drought adaptation in Olea europaea growing in an experimental site plantation in southern Italy (41°06’N, 14°43’E; at an elevation of 250 m a.s.l.). The study was carried out on mature olive plants, subjected to different water availability since 1994. Treatments were a rainfed (non-irrigated) and fully irrigated regime (100% of ETc throughout the irrigation season). During the growing season 2007, plants were continuously monitored by automatic point dendrometers measuring stem radius variation. Whole-plant water use was determined using a xylem sap flow method (compensation heat-pulse technique). Additional ecophysiological parameters, such as stomatal conductance and water potential were periodically measured, as well as vegetative development and biochemical characteristics. Stem Maximum Daily Shrinkage (MDS) and sap flux were also compared. Results were evaluated to investigate water use strategies, functional, and structural acclimation to watering. These observations were analysed to identify valuable parameters that may be used to implement automatic management irrigation practices in olive tree plantations.

Constraints on plant water status and water use indicators were studied in orchard grown Olea europaea L. trees, cv. Nocellara del Belice, in order to assess productivity and drought adaptation. The study was conducted on 16-year-old grafted plants, grown under different water treatments for 14 years in an experimental site plantation in southern Italy. Water treatments were: a non-irrigated, rainfed, control (T0) and three treatments that received seasonal water amount equivalent to 33 and 66% of crop evapotranspiration (ETC) from the beginning of pit hardening to early fruit veraison (respectively T33 and T66), and 100% of ETC throughout the irrigation season (T100). During 2006 and 2007 growing seasons, plants were continuously monitored by automatic point dendrometers measuring stem radius variation and whole-plant water use was determined using a xylem sap flow method (compensation heat-pulse technique). Additional ecophysiological parameters, such as stomatal conductance and water potentials were periodically measured, as well as vegetative development. Predawn leaf water potential decreased in rainfed trees and this was associated with increasing soil moisture deficit, while the difference between predawn and midday leaf water potentials increased, suggesting anisohydric regulation of plant water potential. Olive trees exhibited a tight stomatal control over transpiration, but insufficient to prevent loss of hydraulic conductance under severe drought stress. The stem radial increment and sap flux did not differ consistently between water treatments in the mild year (2006), while irrigated trees had higher water use than rainfed trees in the dry year (2007). However, plants growing under rainfed conditions showed a small increase in maximum daily shrinkage during drought periods compared to irrigated ones, although no marked differences were recorded between irrigated treatments. The mean daily transpiration rate, canopy conductance and decoupling coefficient were higher in 2006 than in 2007, the driest year, only, and in fully irrigated rather than rainfed plants. These results support the idea that rainfed trees had more conservative water use strategies than irrigated trees, and that deficit-irrigated trees acclimated somewhat functionally and structurally to long-term partial watering. Based on these observations, we can argue that loss of hydraulic conductance is an important mechanism for increasing stomatal control of transpiration under progressive soil drying. Another view implies that the increasing difference between soil and leaf water potential during summer induced stomatal closure and minimized the risk of a collapse of the conductive system, decreasing transpiration and reducing hydraulic conductance.

Changes of stem diameter were continuously monitored during winter in two field-grown poplar clones, using automatic point dendrometers. The objective of this study was to find an analytical solution to seasonal synchronization of stem diameter oscillations and low air temperatures. The study identified to what extent and with what frequency low air temperature induced stem diameter variation in 'Dvina' (P. deltoides) and 'I-214' (Populus x canadensis) poplar clones, after exposure to summer drought. The patterns of reversible stem shrinkage were related to the cycles of low air temperature. Hourly and daily evidence showed that 'I-214' was more sensitive to low air temperatures than 'Dvina'. The analysis of raw data and graphic details implemented with the study of derivative tests allowed an increase in the general sensitivity of the investigation applied to describe the response of poplar clones to environmental conditions. Given these diameter fluctuation patterns, automatic point dendrometers were confirmed to be a reliable non-invasive method for testing the sensitivity of diameter variation to cold temperature. Variation in rate and duration of daily stem shrinkage in response to low air temperature in winter appeared to occur independently of the effects of water deficit suffered by plants the previous summer.

Deadwood is an important component for conserving carbon stock and maintaining species diversity. Scarce information is, at present, available concerning the amount and composition of deadwood in Mediterranean-type ecosystems. In this study, 21 sites were chosen to characterize different forest types among representative managed and unmanaged stands in the Central Apennines (Molise, Italy). Data were collected to assess living tree and deadwood volumes, and the relative abundance of different deadwood components in decay classes. The information gathered was related to human-induced disturbances on a regional scale. There were substantial differences in the deadwood volumes between managed and unmanaged stands, although this was not the case in the living tree volumes. Deadwood volumes were larger in unmanaged than in managed stands. In particular, large amounts of deadwood were found in managed Mediterranean and Anatolian fir forests, probably due to minimal management practices. Dead downed trees were less represented in managed forests as they are normally removed to facilitate logging activities. Logs occurred more frequently in managed stands as logging residues left on site. Most deadwood material belonged to early decay classes. Proportionally larger amounts of deadwood ascribed to class 1 in managed stands correlated with recent cutting activities. The relatively large amounts of deadwood attributed in unmanaged stands to class 3 demonstrate its longer persistence in unmanaged forests. This study represents a first systematic analysis of deadwood occurrence in a typical Mediterranean forest area, and should be useful in defining important objectives for sustainable forest management.

With the aim to examine their potentials as renewable resources to decontaminate polluted soils, growth, photosynthesis and nitrogen balance were analyzed in two poplar species (Populus x canadensis, Adda clone and Populus alba, Villafranca clone) to investigate the tolerance to high copper (Cu) concentrations. The two clones showed different responses to Cu in terms of tolerance and metal allocation: P. x canadensis accumulated Cu in roots, displaying features sought in plants suitable for phytostabilization, while P. alba accumulated the metal in leaves, like an indicator species.

iForest is an Open Access, peer-reviewed online journal published by the Italian Society of Silviculture and Forest Ecology (SISEF). The journal encompasses a broad range of research aspects concerning forest science: forest ecology, biodiversity/genetics and ecophysiology, silviculture, forest inventory and planning, forest protection and monitoring, forest harvesting, landscape ecology, forest history, wood technology. iForest is freely and universally accessible online. It has been selected for coverage in the following ISI Thomson Reuters products (Impact Factor expected in the 2012 JCR): Journal Citation Reports - Science Edition (JCR) Science Citation Index - Expanded Current Contents / Agriculture, Biology & Environmental Sciences iForest is indexed by Elsevier Products (Scopus(TM), Embase(TM), etc), in the directory of Open Access Journal (DOAJ(TM)), and is a member of the Crossref consortium(TM).

The response of mature olive (Olea europaea L.) trees to both regulated deficit irrigation and fertigation was studied for some consecutive years in sub-humid (Italy) and semi-arid conditions (Spain). All cultivars tested in these experiments were preferentially for table olive consumption (pickling and double-aptitude). Data from these long-term studies on field-grown, mature trees are summarized for assessing common effects of water and nutrient supply on plant behaviour and fruit yield. Seasonal yield variations were observed, and showed that the effect of irrigation treatments was somewhat more gradual in the >on> than in the >off> year. Differences amongst cultivars were always marked. Dry matter accumulation in pulp and pit was positively affected by progressively increasing the amount of water supplied to plants, regardless of years and cultivars. The ratio between pulp and pit fresh weight was negatively affected by irrigation, while fruit size was positively influenced by the gradual increase of irrigation water. Average nitrogen levels in leaves were generally above the deficiency threshold at both experimental plantations. Crop yield was not consistently increased by addition of soil nutrients. The effect of fertigation treatments was relatively uninfluential on oil accumulation in fruits. However, polyphenols in oil samples decreased progressively as the addition of nutrients increased. Critical aspects and strategic decisions in modern olive growing are the selection of cultivar, the supply of water, the option of fertilization, together with other orchard management practices. In this paper we outline various aspects of long-term studies in experimental olive plantations with the aim of highlighting inter-regulatory processes, involving plant growth and crop yield, which must be taken into account when planning future field research and modelling exercises.

The effects of elevated atmospheric CO 2 on in situ soil respiration and belowground biomass were studied in a FACE (Free Air CO 2 Enrichment) facility. A Mediterranean grassland community was exposed to elevated and ambient CO 2 concentrations in a mini-FACE system in Tuscany (Italy). We quantified litter mass and chemistry, root growth and turnover, CO 2 efflux from soils, and soil microbial biomass. Elevated CO 2 caused limited increases in aboveground production. Litter quality, fine root turnover, microbial biomass, root growth, and root biomass were not significantly affected by elevated CO 2 , except during some periods. Our results suggest that elevated atmospheric CO 2 might moderately accelerate inputs of organic matter to soil carbon pools in Mediterranean grasslands, but it may also partially accelerate losses of carbon from belowground by stimulating soil respiration.

The relative importance that biomechanical and biochemical leaf traits have on photosynthetic capacity would depend on a complex interaction of internal architecture and physiological differences. Changes in photosynthetic capacity on a leaf area basis and anatomical properties during leaf development were studied in a deciduous tree, Prunus persica, and an evergreen shrub, Olea europaea. Photosynthetic capacity increased as leaves approached full expansion. Internal CO2 transfer conductance (g i) correlated with photosynthetic capacity, although, differences between species were only partially explained through structural and anatomical traits of leaves. Expanding leaves preserved a close functional balance in the allocation of resources of photosynthetic component processes. Stomata developed more rapidly in olive than in peach. Mesophyll thickness doubled from initial through final stages of development when it was twice as thick in olive as in peach. The surface area of mesophyll cells exposed to intercellular air spaces per unit leaf area tended to decrease with increasing leaf expansion, whereas, the fraction of mesophyll volume occupied by the intercellular air spaces increased strongly. In the sclerophyllous olive, structural protection of mesophyll cells had priority over efficiency of photochemical mechanisms with respect to the broad-leaved peach. The photosynthetic capacity of these woody plants during leaf development relied greatly on mesophyll properties, more than on leaf mass per area ratio (LMA) or nitrogen (N) allocation. Age-dependent changes in diffusion conductance and photosynthetic capacity affected photosynthetic relationships of peach versus olive foliage, evergreen leaves maturing functionally and structurally a bit earlier than deciduous leaves in the course of adaptation for xeromorphy.

SUMMARY Net photosynthesis, dark respiration, chlorophyll and carbohydrate content, and leaf growth in plants of deciduous peach (Prunus persica (L.) Batsch.) and evergreen olive (Olea europaea L.) grown in controlled environmental conditions were measured to assess changes in carbon balance during leaf development at the 6th, 12th and 16th nodes (first flush) from the beginning of expansion to full maturity. A simulation model was written including growth traits, physiological measurements and meteorological data. In both species, gas exchange varied with the percentage of leaf expansion, regardless of the node examined. The relationships between net daily CO2 assimilation (24 h), chlorophyll content, and the ratio of leaf mass per area, across all nodes, differed between species. Photosynthetic capacity differed significantly between different degrees of leaf expansion in both species. The model predicted differences in leaf carbohydrate balance between peach and olive. The onset of carbohydrate export from individual leaves varied with species, being 18 ‐ 19 d and 28 ‐ 29 d from emergence in peach and olive, respectively.