Regenerating oak trees with different techniques has long-lasting legacy effects on root development, stem growth, and plant physiology.

Regeneration methods can have legacy effects on tree physiology and growth via differential root development and affect forest climate sensitivity. However, there are few studies providing a long term perspective on how forest regeneration techniques affect root development and physiology of established seedlings that have grown into trees. This study investigates leaf C, O and N isotope composition (δ13C, δ18O, δ15N) and stem growth in approximately 20-year-old oak (Quercus robur) trees regenerated in two stands by three methods: direct acorn sowing in the field, bare-root planting preceded by root pruning, and containerized planting with the root plug intact.

Herbivory legacy modifies leaf economic spectrum and drought tolerance in two tree species.

The concurring effect of herbivory by wild ungulates and drought events is experiencing a notable increase in Mediterranean and temperate forests. While many studies have addressed the influence of drought on plant susceptibility to herbivory, it appears crucial to comprehend the impact of prolonged browsing on the physiological response of plants to increasing water deficit. To this end, we analyzed the effect of long-term recurrent herbivory by ungulates on physiological, biochemical, anatomical and morphological variables of Ilex aquifolium and Fagus sylvatica saplings during the growing seasons of 2018 and 2019 in a mixed sub-Mediterranean forest.

Hydraulic plasticity and water use regulation act to maintain the hydraulic safety margins of Mediterranean trees in rainfall exclusion experiments.

Hydraulic failure due to xylem embolism has been identified as one of the main mechanisms involved in drought-induced forest decline. Trees vulnerability to hydraulic failure depends on their hydraulic safety margin (HSM). While it has been shown that HSM globally converges between tree species and biomes, there is still limited knowledge regarding how HSM can adjust locally to varying drought conditions within species.

Linking functional composition moments of the sub-Mediterranean ecotone with environmental drivers.

Introduction: Functional trait-based approaches are extensively applied to the study of mechanisms governing community assembly along environmental gradients. These approaches have been classically based on studying differences in mean values among species, but there is increasing recognition that alternative metrics of trait distributions should be considered to decipher the mechanisms determining community assembly and species coexistence. Under this framework, the main aim of this study is to unravel the effects of environmental conditions as drivers of plant community assembly in sub-Mediterranean ecotones.

Living at the edge: the functional niche occupation of woody plant communities in the submediterranean ecotone.

Background And Aims: Submediterranean areas are rich ecotones, where slight modifications in environmental conditions can lead to substantial changes in the composition of plant communities. They thus offer an ideal scenario to examine plant community assembly. In this study, we followed a trait-based approach including intraspecific variability to elucidate (1) the relationship between niche occupancy components and species richness, (2) the processes governing the assembly of these communities and (3) the contribution of intraspecific trait variability in shaping the functional trait space.

Carbon isotope composition of respired CO2 in woody stems and leafy shoots of three tree species along the growing season: physiological drivers for respiratory fractionation.

The carbon isotope composition of respired CO2 (δ13CR) and bulk organic matter (δ13CB) of various plant compartments informs about the isotopic fractionation and substrate of respiratory processes, which are crucial to advance the understanding of carbon allocation in plants. Nevertheless, the variation across organs, species and seasons remains poorly understood. Cavity Ring-Down Laser Spectroscopy was applied to measure δ13CR in leafy shoots and woody stems of maple (Acer platanoides L.

Large investment of stored nitrogen and phosphorus in female cones is consistent with infrequent reproduction events of , a high value woody oil crop in Northeast Asia.

is famous for its high-quality timber production all the way and is much more famous for its high value health-care nut oil production potential since 1990's, but the less understanding of its reproduction biology seriously hindered its nut productivity increase. Exploring the effects of reproduction on nutrient uptake, allocation and storage help to understand and modify reproduction patterns in masting species and high nut yield cultivar selection and breeding. Here, we compared seasonality in growth and in nitrogen ([N]) and phosphorus ([P]) concentrations in needles, branches and cones of reproductive (cone-bearing) and vegetative branches (having no cones) of during a masting year.

Beneficial and pathogenic plant-microbe interactions during flooding stress.

The number and intensity of flood events will likely increase in the future, raising the risk of flooding stress in terrestrial plants. Understanding flood effects on plant physiology and plant-associated microbes is key to alleviate flooding stress in sensitive species and ecosystems. Reduced oxygen supply is the main constrain to the plant and its associated microbiome.

Three years of warming and rainfall reduction alter leaf physiology but not relative abundance of an annual species in a Mediterranean savanna.

Increasing air temperatures and decreasing rainfall can alter Mediterranean ecosystems, where summer heat and drought already limit plant regeneration. Manipulative field studies can help to understand and anticipate community responses to climate changes. In a Mediterranean oak wooded pasture, we have investigated the effects of warming (W, via open-top chambers increasing 1.

Drought acclimation of Quercus ilex leaves improves tolerance to moderate drought but not resistance to severe water stress.

Increasing temperature and drought can result in leaf dehydration and defoliation even in drought-adapted tree species such as the Mediterranean evergreen Quercus ilex L. The stomatal regulation of leaf water potential plays a central role in avoiding this phenomenon and is constrained by a suite of leaf traits including hydraulic conductance and vulnerability, hydraulic capacitance, minimum conductance to water vapour, osmotic potential and cell wall elasticity. We investigated whether the plasticity in these traits may improve leaf tolerance to drought in two long-term rainfall exclusion experiments in Mediterranean forests.

Priming of Plant Defenses against by Elm ( Mill.) Fungal Endophytes.

Some fungal endophytes of forest trees are recognized as beneficial symbionts against stresses. In previous works, two elm endophytes from the classes Cystobasidiomycetes and Eurotiomycetes promoted host resistance to abiotic stress, and another elm endophyte from Dothideomycetes enhanced host resistance to Dutch elm disease (DED). Here, we hypothesize that the combined effect of these endophytes activate the plant immune and/or antioxidant system, leading to a defense priming and/or increased oxidative protection when exposed to the DED pathogen .

Impact of successive spring frosts on leaf phenology and radial growth in three deciduous tree species with contrasting climate requirements in central Spain.

Rear-edge tree populations forming the equatorward limit of distribution of temperate species are assumed to be more adapted to climate variability than central (core) populations. However, climate is expected to become more variable and the frequency of climate extremes is forecasted to increase. Climatic extreme events such as heat waves, dry spells and spring frosts could become more frequent, and negatively impact and jeopardize rear-edge stands.

Stem endophytes increase root development, photosynthesis, and survival of elm plantlets (Ulmus minor Mill.).

Long-lived trees benefit from fungal symbiotic interactions in the adaptation to constantly changing environments. Previous studies revealed a core fungal endobiome in Ulmus minor which has been suggested to play a critical role in plant functioning. Here, we hypothesized that these core endophytes are involved in abiotic stress tolerance.

Epigenetic responses of hare barley (Hordeum murinum subsp. leporinum) to climate change: an experimental, trait-based approach.

The impact of reduced rainfall and increased temperatures forecasted by climate change models on plant communities will depend on the capacity of plant species to acclimate and adapt to new environmental conditions. The acclimation process is mainly driven by epigenetic regulation, including structural and chemical modifications on the genome that do not affect the nucleotide sequence. In plants, one of the best-known epigenetic mechanisms is cytosine-methylation.

Stem metabolism under drought stress - a paradox of increasing respiratory substrates and decreasing respiratory rates.

Metabolic changes underpinning drought-induced variations in stem respiration (R ) are unknown. We measured R rates and metabolite and gene expression profiles in Ulmus minor Mill. and Quercus ilex L.

Changes in plant function and root mycobiome caused by flood and drought in a riparian tree.

Under increasingly harsh climatic conditions, conservation of threatened species requires integrative studies to understand stress tolerance. Riparian Ulmus minor Mill. populations have been massively reduced by Dutch Elm disease (DED).

Hydraulic acclimation in a Mediterranean oak subjected to permanent throughfall exclusion results in increased stem hydraulic capacitance.

Stem water storage capacity and hydraulic capacitance (C ) play a crucial role in tree survival under drought-stress. To investigate whether C adjusts to increasing water deficit, variation in stem water content (StWC) was monitored in vivo for 2 years and related to periodical measurements of tree water potential in Mediterranean Quercus ilex trees subjected either to permanent throughfall exclusion (TE) or to control conditions. Seasonal reductions in StWC were larger in TE trees relative to control ones, resulting in greater seasonal C (154 and 80 kg m MPa , respectively), but only during the first phase of the desorption curve, when predawn water potential was above -1.

Respiratory costs of producing and maintaining stem biomass in eight co-occurring tree species.

Given the importance of carbon allocation for plant performance and fitness, it is expected that competition and abiotic stress influence respiratory costs associated with stem wood biomass production and maintenance. In this study, stem respiration (R) was measured together with stem diameter increment in adult trees of eight co-occurring species in a sub-Mediterranean forest stand for 2 years. We estimated growth R (Rg), maintenance R (Rm) and the growth respiration coefficient (GRC) using two gas exchange methods: (i) estimating Rg as the product of growth and GRC (then Rm as R minus Rg) and (ii) estimating Rm from temperature-dependent kinetics of basal Rm at the dormant season (then Rg as R minus Rm).

Increased root investment can explain the higher survival of seedlings of 'mesic' Quercus suber than 'xeric' Quercus ilex in sandy soils during a summer drought.

In Mediterranean-type ecosystems, drought is considered the main ecological filter for seedling establishment. The evergreen oaks Quercus ilex L. and Quercus suber L.

Further insights into the components of resistance to Ophiostoma novo-ulmi in Ulmus minor: hydraulic conductance, stomatal sensitivity and bark dehydration.

Dutch elm disease (DED) is a vascular disease that has killed over 1 billion elm trees. The pathogen spreads throughout the xylem network triggering vessel blockage, which results in water stress, tissue dehydration and extensive leaf wilting in susceptible genotypes. We investigated the differences between four Ulmus minor Mill.

A molecular approach to drought-induced reduction in leaf CO exchange in drought-resistant Quercus ilex.

Drought-induced reduction of leaf gas exchange entails a complex regulation of the plant leaf metabolism. We used a combined molecular and physiological approach to understand leaf photosynthetic and respiratory responses of 2-year-old Quercus ilex seedlings to drought. Mild drought stress resulted in glucose accumulation while net photosynthetic CO uptake (P ) remained unchanged, suggesting a role of glucose in stress signaling and/or osmoregulation.

Surface properties and physiology of Ulmus laevis and U. minor samaras: implications for seed development and dispersal.

Plant surface properties influence solid-liquid interactions and matter exchange between the organs and their surrounding environment. In the case of fruits, surface processes may be of relevance for seed production and dispersal. To gain insight into the relationship between surface structure, chemical composition and function of aerial reproductive organs, we performed diverse experiments with the dry, winged fruits, or samaras, of Ulmus laevis Pall.

Stem hydraulic capacitance decreases with drought stress: implications for modelling tree hydraulics in the Mediterranean oak Quercus ilex.

Hydraulic modelling is a primary tool to predict plant performance in future drier scenarios. However, as most tree models are validated under non-stress conditions, they may fail when water becomes limiting. To simulate tree hydraulic functioning under moist and dry conditions, the current version of a water flow and storage mechanistic model was further developed by implementing equations that describe variation in xylem hydraulic resistance (R ) and stem hydraulic capacitance (C ) with predawn water potential (Ψ ).

Drought-induced shoot dieback starts with massive root xylem embolism and variable depletion of nonstructural carbohydrates in seedlings of two tree species.

Combining hydraulic- and carbon-related measurements helps to understand drought-induced plant mortality. Here, we investigated the role that plant respiration (R) plays in determining carbon budgets under drought. We measured the hydraulic conductivity of stems and roots, and gas exchange and nonstructural carbohydrate (NSC) concentrations of leaves, stems and roots of seedlings of two resprouting species exposed to drought or well-watered conditions: Ulmus minor (riparian tree) and Quercus ilex (dryland tree).