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Alfonso Escudero - One of the best experts on this subject based on the ideXlab platform.
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Responses of photosynthetic parameters to differences in winter temperatures throughout a temperature gradient in two Evergreen Tree species
European Journal of Forest Research, 2016Co-Authors: Sonia Mediavilla, Patricia González-zurdo, Josefa Babiano, Alfonso EscuderoAbstract:The temperature dependence of photosynthetic parameters has been a focus of interest during recent years owing to its profound implications in the new climate scenario. Many studies have addressed the short-term responses of photosynthetic parameters to temperature change. Less attention has been given to the intraspecific variability in the biochemical parameters of photosynthesis in response to differences in growth temperature. This study explores the effects of winter harshness on the leaf traits of two Evergreen Tree species (Quercus ilex and Q. suber). Leaf mass per unit area (LMA) and the concentrations of fiber, nitrogen (N), soluble protein, chlorophyll and ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) were determined in both species throughout a temperature gradient. Several photosynthetic parameters [maximum carboxylation rate (V cmax), maximum light-driven electron flux (J max), day respiration rate (R d) and relative stomatal limitation to photosynthesis] were assessed by measuring leaf response curves of net CO2 assimilation versus intercellular CO2 partial pressure. LMA and structural carbohydrate concentrations increased with the decrease in winter temperatures, whereas N concentrations did not show definite patterns. Chlorophyll, soluble proteins, Rubisco, V cmax and J max declined with the decrease in winter temperatures, whereas R d at a set common temperature (25 °C) was higher at colder sites. Our results suggest that an increase in LMA and in the concentration of structural carbohydrates in cold environments is associated with a reduced N allocation to the photosynthetic machinery, which leads to reduced photosynthetic capacity.
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patterns of leaf morphology and leaf n content in relation to winter temperatures in three Evergreen Tree species
International Journal of Biometeorology, 2012Co-Authors: Sonia Mediavilla, Patricia Gonzalezzurdo, Victoria Gallardolopez, Alfonso EscuderoAbstract:The competitive equilibrium between deciduous and perennial species in a new scenario of climate change may depend closely on the productivity of leaves along the different seasons of the year and on the morphological and chemical adaptations required for leaf survival during the different seasons. The aim of the present work was to analyze such adaptations in the leaves of three Evergreen species (Quercus ilex, Q. suber and Pinus pinaster) and their responses to between-site differences in the intensity of winter harshness. We explore the hypothesis that the harshness of winter would contribute to enhancing the leaf traits that allow them to persist under conditions of stress. The results revealed that as winter harshness increases a decrease in leaf size occurs in all three species, together with an increase in the content of nitrogen per unit leaf area and a greater leaf mass per unit area, which seems to be achieved only through increased thickness, with no associated changes in density. P. pinaster was the species with the most intense response to the harshening of winter conditions, undergoing a more marked thickening of its needles than the two Quercus species. Our findings thus suggest that lower winter temperatures involve an increase in the cost of leaf production of Evergreen species, which must be taken into account in the estimation of the final cost and benefit balance of Evergreens. Such cost increases would be more pronounced for those species that, like P. pinaster, show a stronger response to the winter cold.
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morphological and chemical leaf composition of mediterranean Evergreen Tree species according to leaf age
Trees-structure and Function, 2011Co-Authors: Sonia Mediavilla, Patricia Gonzalezzurdo, A Garciaciudad, Alfonso EscuderoAbstract:Changes in morphology [leaf dry mass per unit area (LMA), thickness and density] and chemical composition (macronutrients and fibres content) in different age leaves of eight Evergreen Mediterranean woody species were investigated. LMA and leaf thickness increased with leaf age increasing. Young tissues possessed higher concentrations of N, P, K, and Mg and lower Ca concentrations on a dry mass basis. However, mineral content was independent of age on leaf area basis (except for Ca content) suggesting that the changes in mineral concentration with leaf ageing are due to dilution in the larger dry mass accumulated in the oldest leaves. Leaf tissue density (LTD) increased during the first year of the leaf life. Lignin and hemicellulose concentrations did not vary along leaf life and the cellulose concentration increased with leaf age in most species between the current-year and the one-year old leaves. Our results suggested that physical leaf reinforcement with a higher cellulose concentration and density might be a leaf response to the unfavourable climatic conditions during the first winter.
Sonia Mediavilla - One of the best experts on this subject based on the ideXlab platform.
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Responses of photosynthetic parameters to differences in winter temperatures throughout a temperature gradient in two Evergreen Tree species
European Journal of Forest Research, 2016Co-Authors: Sonia Mediavilla, Patricia González-zurdo, Josefa Babiano, Alfonso EscuderoAbstract:The temperature dependence of photosynthetic parameters has been a focus of interest during recent years owing to its profound implications in the new climate scenario. Many studies have addressed the short-term responses of photosynthetic parameters to temperature change. Less attention has been given to the intraspecific variability in the biochemical parameters of photosynthesis in response to differences in growth temperature. This study explores the effects of winter harshness on the leaf traits of two Evergreen Tree species (Quercus ilex and Q. suber). Leaf mass per unit area (LMA) and the concentrations of fiber, nitrogen (N), soluble protein, chlorophyll and ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) were determined in both species throughout a temperature gradient. Several photosynthetic parameters [maximum carboxylation rate (V cmax), maximum light-driven electron flux (J max), day respiration rate (R d) and relative stomatal limitation to photosynthesis] were assessed by measuring leaf response curves of net CO2 assimilation versus intercellular CO2 partial pressure. LMA and structural carbohydrate concentrations increased with the decrease in winter temperatures, whereas N concentrations did not show definite patterns. Chlorophyll, soluble proteins, Rubisco, V cmax and J max declined with the decrease in winter temperatures, whereas R d at a set common temperature (25 °C) was higher at colder sites. Our results suggest that an increase in LMA and in the concentration of structural carbohydrates in cold environments is associated with a reduced N allocation to the photosynthetic machinery, which leads to reduced photosynthetic capacity.
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patterns of leaf morphology and leaf n content in relation to winter temperatures in three Evergreen Tree species
International Journal of Biometeorology, 2012Co-Authors: Sonia Mediavilla, Patricia Gonzalezzurdo, Victoria Gallardolopez, Alfonso EscuderoAbstract:The competitive equilibrium between deciduous and perennial species in a new scenario of climate change may depend closely on the productivity of leaves along the different seasons of the year and on the morphological and chemical adaptations required for leaf survival during the different seasons. The aim of the present work was to analyze such adaptations in the leaves of three Evergreen species (Quercus ilex, Q. suber and Pinus pinaster) and their responses to between-site differences in the intensity of winter harshness. We explore the hypothesis that the harshness of winter would contribute to enhancing the leaf traits that allow them to persist under conditions of stress. The results revealed that as winter harshness increases a decrease in leaf size occurs in all three species, together with an increase in the content of nitrogen per unit leaf area and a greater leaf mass per unit area, which seems to be achieved only through increased thickness, with no associated changes in density. P. pinaster was the species with the most intense response to the harshening of winter conditions, undergoing a more marked thickening of its needles than the two Quercus species. Our findings thus suggest that lower winter temperatures involve an increase in the cost of leaf production of Evergreen species, which must be taken into account in the estimation of the final cost and benefit balance of Evergreens. Such cost increases would be more pronounced for those species that, like P. pinaster, show a stronger response to the winter cold.
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morphological and chemical leaf composition of mediterranean Evergreen Tree species according to leaf age
Trees-structure and Function, 2011Co-Authors: Sonia Mediavilla, Patricia Gonzalezzurdo, A Garciaciudad, Alfonso EscuderoAbstract:Changes in morphology [leaf dry mass per unit area (LMA), thickness and density] and chemical composition (macronutrients and fibres content) in different age leaves of eight Evergreen Mediterranean woody species were investigated. LMA and leaf thickness increased with leaf age increasing. Young tissues possessed higher concentrations of N, P, K, and Mg and lower Ca concentrations on a dry mass basis. However, mineral content was independent of age on leaf area basis (except for Ca content) suggesting that the changes in mineral concentration with leaf ageing are due to dilution in the larger dry mass accumulated in the oldest leaves. Leaf tissue density (LTD) increased during the first year of the leaf life. Lignin and hemicellulose concentrations did not vary along leaf life and the cellulose concentration increased with leaf age in most species between the current-year and the one-year old leaves. Our results suggested that physical leaf reinforcement with a higher cellulose concentration and density might be a leaf response to the unfavourable climatic conditions during the first winter.
Hiroaki Ishii - One of the best experts on this subject based on the ideXlab platform.
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Acclimation potential of three Evergreen Tree species to wind-induced water stress in an urban green-roof environment
Urban Forestry & Urban Greening, 2019Co-Authors: Yuki Namba, Sumihiro Inoue, Masashi Fujita, Yuiko Noguchi, Chinatsu Hara, Hiroaki IshiiAbstract:Abstract We compared acclimation potential of three native, Evergreen Tree species to wind-exposure in an urban green-roof environment. One year after planting on the green roof, Machilus thunbergii retained all leaves and produced new leaves. In contrast, Fraxinus griffithii, and Quercus myrsinifolia shed all leaves but produced more new leaves than the previous year. After two years, current-year leaves of all three species had acclimated hydraulically (lower osmotic potentials at saturation and turgor loss) to wind-induced water stress and leaf number increased to four to eight times the initial amount. When Trees were exposed to simulated winds in a greenhouse experiment, osmotic adjustment was observed for current-year leaves of M. thunbergii, whereas leaves of F. griffithii and Q. myrsinifolia had hydraulic traits more vulnerable to wind-induced water stress (higher osmotic potential and relative water content at turgor loss). We inferred that, M. thunbergii invests in hydraulic acclimation to retain current-year leaves in response to increased wind, whereas F. griffithii and Q. myrsinifolia allocate resources to new leaf production. Our results suggest both strategies achieve Tree-level acclimation to wind exposure.
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Oviposition site selection by Japanese gypsy moth (Lymatria dispar japonica) in a warm-temperate secondary forest in western Japan
Forest Science and Technology, 2016Co-Authors: Takeshi Sasaki, Shota Jikumaru, Wakana Azuma, Keiko Kuroda, Hiroaki IshiiAbstract:The larvae of Japanese gypsy moth (JGM, Lymantria dispar japonica) are highly polyphagous and considered a serious pest that cause significant ecological and economic losses in forests. Monitoring of egg masses is important to prevent large outbreaks of JGM from occurring in their native range. To investigate oviposition site selection by JGM, we analyzed the occurrence and spatial distribution of egg masses across various Evergreen Tree species within a secondary forest dominated by Evergreen broad-leaved Trees in western Japan, following a large outbreak. Egg masses were concentrated on the abaxial surfaces of the leaves of a few Evergreen Tree species. There was a strong preference for Camellia japonica L., on which more than 75% of the egg masses were found. Egg masses were only found on Evergreen Tree species with large leaves (leaf area >10 cm2 and leaf dry mass >0.1 g). The spatial distribution of egg masses were clustered at scales around 1‒2 m. For effective monitoring of JGM egg masses in warm-t...
Akio Takenaka - One of the best experts on this subject based on the ideXlab platform.
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Structural variation in current-year shoots of broad-leaved Evergreen Tree saplings under forest canopies in warm temperate Japan.
Tree physiology, 1997Co-Authors: Akio TakenakaAbstract:Stem length and leaf area of current-year shoots were measured in saplings of eight broad-leaved Evergreen Tree species growing under a forest canopy. Stem length varied over a range of one to two orders of magnitude within each species. In all species, both the number of leaves and the mean stem length between successive leaves were greater in longer shoots. Mean leaf size and stem length were not correlated in six of eight species, and only weakly positively correlated in the other two species. Thus, total leaf area per stem increased with stem length, but not in direct proportion: leaf area per stem length was smaller in shoots with long stems and larger in shoots with short stems. I conclude that the within-species variation in the leaf-stem balance of current-year shoots is related to variation in shoot functional roles, as has been observed for long and short shoots in many deciduous Tree species: shoots with long stems are extension oriented and contribute to the framework of the crown, whereas shoots with short stems serve mainly for leaf display. Among species, large differences were found in the leaf area per stem length ratio. In the species with larger leaf area per stem length ratios, leaves had narrower blades or longer petioles, or both, resulting in a reduction of mutual shading among the leaves on the shoot.
Jorgpeter Schnitzler - One of the best experts on this subject based on the ideXlab platform.
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seasonal pattern of monoterpene synthase activities in leaves of the Evergreen Tree quercus ilex
Physiologia Plantarum, 2002Co-Authors: Robert J Fischbach, Michael Staudt, Ina Zimmer, Serge Rambal, Jorgpeter SchnitzlerAbstract:Monoterpene synthase activities were measured in current year and 1-year-old leaves of holm oak (Quercus ilex L.). The monoterpene synthase activities of the leaves strongly changed with leaf development and leaf age. Enzyme activities increased rapidly in spring after leaf emergence, reaching maximum values in summer, which declined during the following winter period. In the next spring monoterpene synthase activities recovered in the old leaves to about one-third of values in the previous years and showed a similar seasonal variation as in young leaves. In both leaf age classes the pattern of enzymatic monoterpene formation was stable with α-pinene (33%), β-pinene (28%), and myrcene (26%) as prominent compounds followed by minor fractions of sabinene (10%) and limonene (3%). Monoterpene emission correlated with the activity of the synthetizing enzymes, indicating that monoterpene synthase activities in Q. ilex reflect the seasonal monoterpene emission potential of the leaves.