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Tree Physiology

Jane R Foster
Defoliation outbreaks are biological disturbances that alter tree growth and mortality in temperate forests. Trees respond to defoliation in many ways; some recover rapidly, while others decline gradually or die. Functional traits such as xylem anatomy, growth phenology or non-structural carbohydrate (NSC) storage could explain these responses, but idiosyncratic measures used by defoliation studies have frustrated efforts to generalize among species. Here, I test for functional differences with published growth and mortality data from 37 studies, including 24 tree species and 11 defoliators from North America and Eurasia...
April 21, 2017: Tree Physiology
Galina Timofeeva, Kerstin Treydte, Harald Bugmann, Andreas Rigling, Marcus Schaub, Rolf Siegwolf, Matthias Saurer
Drought frequency is increasing in many parts of the world and may enhance tree decline and mortality. The underlying physiological mechanisms are poorly understood, however, particularly regarding chronic effects of long-term drought and the response to increasing temperature and vapor pressure deficit (VPD). We combined analyses of radial growth and stable carbon isotope ratios (δ13C) in tree rings in a mature Scots pine (Pinus sylvestris L.) forest over the 20th century to elucidate causes of tree mortality in one of the driest parts of the European Alps (Pfynwald, Switzerland)...
April 21, 2017: Tree Physiology
Riichi Oguchi, Tsutom Hiura, Kouki Hikosaka
Gap formation increases the light intensity in the forest understorey. The growth responses of seedlings to the increase in light availability show interspecific variation, which is considered to promote biodiversity in forests. At the leaf level, some species increase their photosynthetic capacity in response to gap formation, whereas others do not. Here we address the question of whether the interspecific difference in the photosynthetic response results in the interspecific variation in the growth response...
April 19, 2017: Tree Physiology
Jose A Ramírez-Valiente, Jeannine Cavender-Bares
In seasonally dry tropical forest regions, drought avoidance during the dry season coupled with high assimilation rates in the wet season is hypothesized to be an advantageous strategy for forest trees in regions with severe and long dry seasons. In contrast, where dry seasons are milder, drought tolerance coupled with a conservative resource-use strategy is expected to maximize carbon assimilation throughout the year. Tests of this hypothesis, particularly at the intraspecific level, have been seldom conducted...
April 13, 2017: Tree Physiology
Elisabet Martínez-Sancho, Isabel Dorado-Liñán, Ingo Heinrich, Gerhard Helle, Annette Menzel
Drought is a key limiting factor for tree growth in the Mediterranean Basin. However, the variability in acclimation via xylem traits is largely unknown. We studied tree growth and vessel features of Quercus petraea (Matt.) Lieb. in five marginal stands across southern Europe. Tree-ring width (TRW), mean earlywood vessel area (MVA) and number of earlywood vessels (NV) as well as theoretical hydraulic conductivity (Kh) chronologies were developed for the period 1963-2012. Summer drought signals were consistent among TRW chronologies; however, climatic responses of vessel features differed considerably among sites...
April 10, 2017: Tree Physiology
Angela Luisa Prendin, Giai Petit, Marco Carrer, Patrick Fonti, Jesper Björklund, Georg von Arx
The analysis of xylem cell anatomical features in dated tree rings provides insights into xylem functional responses and past growth conditions at intra-annual resolution. So far, special focus has been given to the lumen of the water-conducting cells, whereas the equally relevant cell wall thickness (CWT) has been less investigated due to methodological limitations. Here we present a novel approach to measure tracheid CWT in high-resolution images of wood cross-sections that is implemented within the specialized image-analysis tool 'ROXAS'...
April 4, 2017: Tree Physiology
Courtney E Campany, Belinda E Medlyn, Remko A Duursma
Sink limitation is known to reduce plant growth, but it is not known how plant carbon (C) balance is affected, limiting our ability to predict growth under sink-limited conditions. We manipulated soil volume to impose sink limitation of growth in Eucalyptus tereticornis Sm. seedlings. Seedlings were grown in the field in containers of different sizes and planted flush to the soil alongside freely rooted (Free) seedlings. Container volume negatively affected aboveground growth throughout the experiment, and light saturated rates of leaf photosynthesis were consistently lower in seedlings in containers (-26%) compared with Free seedlings...
April 4, 2017: Tree Physiology
Steven A Kannenberg, Richard P Phillips
No abstract text is available yet for this article.
April 4, 2017: Tree Physiology
Alec S Baird, Leander D L Anderegg, Melissa E Lacey, Janneke HilleRisLambers, Elizabeth Van Volkenburgh
Developmental phenotypic plasticity can allow plants to buffer the effects of abiotic and biotic environmental stressors. Therefore, it is vital to improve our understanding of how phenotypic plasticity in ecological functional traits is coordinated with variation in physiological performance in plants. To identify coordinated leaf responses to low-water (LW) versus low-light (LL) availability, we measured leaf mass per area (LMA), leaf anatomical characteristics and leaf gas exchange of juvenile Populus tremuloides Michx...
April 4, 2017: Tree Physiology
M Lüpke, M Leuchner, R Steinbrecher, A Menzel
No abstract text is available yet for this article.
March 25, 2017: Tree Physiology
Rafael Aguilar-Romero, Fernando Pineda-Garcia, Horacio Paz, Antonio González-Rodríguez, Ken Oyama
Oak species (Fagaceae: Quercus) differ in their distribution at the landscape scale, specializing to a certain portion of environmental gradients. This suggests that functional differentiation favors habitat partitioning among closely related species. To elucidate the mechanisms of species coexistence in oak forests, we explored patterns of interspecific variation in functional traits involved in water-use strategies. We tested the hypothesis that oak species segregate along key trade-offs between xylem hydraulic efficiency and safety, and between hydraulic safety and drought avoidance capacity, leading to species niche partitioning across a gradient of aridity...
March 23, 2017: Tree Physiology
Sepideh Zolfaghar, Randol Villalobos-Vega, Melanie Zeppel, James Cleverly, Rizwana Rumman, Matthew Hingee, Nicolas Boulain, Zheng Li, Derek Eamus, Roberto Tognetti
Water resources and their management present social, economic and environmental challenges, with demand for human consumptive, industrial and environmental uses increasing globally. However, environmental water requirements, that is, the allocation of water to the maintenance of ecosystem health, are often neglected or poorly quantified. Further, transpiration by trees is commonly a major determinant of the hydrological balance of woodlands but recognition of the role of groundwater in hydrological balances of woodlands remains inadequate, particularly in mesic climates...
March 23, 2017: Tree Physiology
Dominique Gérant, Morgane Pluchon, Louis Mareschal, Lydie Stella Koutika, Daniel Epron, Torgny Näsholm
Numerous studies have shown that internal nitrogen (N) translocation in temperate tree species is governed by photoperiod duration and temperature. For tropical tree species, the seasonality of rainfall is known to affect growth and foliage production, suggesting that efficient internal N recycling also occurs throughout the year. We tested this hypothesis by comparing the N budgets and N partitioning (non-structural vs structural N) in the different organs of 7-year-old Eucalyptus urophylla (S.T. Blake) × E...
March 22, 2017: Tree Physiology
Hui Zhao, Jing Jiang, Kailong Li, Guifeng Liu, Chung-Jui Tsai
WRKY transcription factors (TFs) are important regulators in the complex stress response signaling networks in plants, but the detailed mechanisms underlying these regulatory networks have not been fully characterized. In the present study, we identified a Group III WRKY gene (PsnWRKY70, Potri.016G137900) from Populussimonii × Populusnigra and explored its function under salt and pathogen stresses. The promoter sequence that is located 2471-bp upstream from the start codon (SC) of PsnWRKY70 contained many stress-responsive cis-elements...
March 22, 2017: Tree Physiology
Alana R O Chin, Stephen C Sillett
Leaf-level anatomical variation is readily apparent within tall tree crowns, yet the relative importance of water and light availability in controlling this variation remains unclear. Sitka spruce (Picea sitchensis, (Bong.) Carr.) thrives in temperate rainforests of the Pacific Northwest, where it has historically reached heights >100 m, despite rarely living more than 400 years alongside redwoods that are five times older. We examined leaves of trees up to 97 m tall using a combination of transverse sections, longitudinal sections, epidermal imprints and whole-leaf measurements to explore the combined effects of water stress and light availability on leaf development in P...
March 21, 2017: Tree Physiology
Yuichiro Hiraoka, Taiichi Iki, Mine Nose, Hiroyuki Tobita, Kenichi Yazaki, Atsushi Watanabe, Yoshitake Fujisawa, Mitsutoshi Kitao
In order to predict the effects of future atmospheric conditions on forest productivity, it is necessary to clarify the physiological responses of major forest tree species to high concentrations of ozone (O3) and carbon dioxide (CO2). Furthermore, intraspecific variation of these responses should also be examined in order to predict productivity gains through tree improvements in the future. We investigated intraspecific variation in growth and photosynthesis of Cryptomeria japonica D. Don, a major silviculture species in Japan, in response to elevated concentrations of O3 (eO3) and CO2 (eCO2), separately and in combination...
March 21, 2017: Tree Physiology
Paula Guzmán-Delgado, Victoria Fernández, Martin Venturas, Jesús Rodríguez-Calcerrada, Luis Gil
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. and Ulmus minor Mill. both at the time of full maturity (green samaras) and of samara dispersal (dry samaras)...
March 21, 2017: Tree Physiology
Danny McCarroll, Matthew Whitney, Giles H F Young, Neil J Loader, Mary H Gagen
Stable carbon isotope ratios from early-wood (EW) and late-wood (LW) are used to test competing models of carbon storage and allocation, providing a cost-effective alternative to measuring and dating non-structural carbohydrates in mature temperate broad-leaf forest trees growing under natural conditions. Annual samples of EW and LW from seven mature oaks (Quercus robur L.) from Scotland, covering AD 1924-2012, were pooled, treated to isolate alpha-cellulose and pyrolysed to measure the carbon isotope ratios...
March 18, 2017: Tree Physiology
Laura Petrucco, Andrea Nardini, Georg von Arx, Matthias Saurer, Paolo Cherubini
The 2003 and 2012 summer seasons were among the warmest and driest of the last 200 years over southeastern Europe, and in particular in the Karst region (northeastern Italy). Starting from winter-spring 2013, several black pines (Pinus nigra J.F. Arnold) suffered crown die-back. Declining trees occurred nearby individuals with no signs of die-back, raising hypotheses about the occurrence of individual-specific hydraulic strategies underlying different responses to extreme drought. We investigated possible processes driving black pine decline by dendrochronological and wood anatomical measurements, coupled with analysis of tree-ring carbon (δ13C) and oxygen (δ18O) isotopic composition in healthy trees (H) and trees suffering die-back (D)...
March 17, 2017: Tree Physiology
Andrew J Hacket-Pain, Jonathan G A Lageard, Peter A Thomas
Interannual variation in radial growth is influenced by a range of physiological processes, including variation in annual reproductive effort, although the importance of reproductive allocation has rarely been quantified. In this study, we use long stand-level records of annual seed production, radial growth (tree ring width) and meteorological conditions to analyse the relative importance of summer drought and reproductive effort in controlling the growth of Fagus sylvatica L., a typical masting species. We show that both summer drought and reproductive effort (masting) influenced growth...
March 17, 2017: Tree Physiology
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