Browsing by Subject "RADIAL GROWTH"

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  • Zweifel, Roman; Etzold, Sophia; Sterck, Frank; Gessler, Arthur; Anfodillo, Tommaso; Mencuccini, Maurizio; von Arx, Georg; Lazzarin, Martina; Haeni, Matthias; Feichtinger, Linda; Meusburger, Katrin; Knuesel, Simon; Walthert, Lorenz; Salmon, Yann; Bose, Arun K.; Schoenbeck, Leonie; Hug, Christian; De Girardi, Nicolas; Giuggiola, Arnaud; Schaub, Marcus; Rigling, Andreas (2020)
    Tree responses to altered water availability range from immediate (e.g. stomatal regulation) to delayed (e.g. crown size adjustment). The interplay of the different response times and processes, and their effects on long-term whole-tree performance, however, is hardly understood. Here we investigated legacy effects on structures and functions of mature Scots pine in a dry inner-Alpine Swiss valley after stopping an 11-yr lasting irrigation treatment. Measured ecophysiological time series were analysed and interpreted with a system-analytic tree model. We found that the irrigation stop led to a cascade of downregulations of physiological and morphological processes with different response times. Biophysical processes responded within days, whereas needle and shoot lengths, crown transparency, and radial stem growth reached control levels after up to 4 yr only. Modelling suggested that organ and carbon reserve turnover rates play a key role for a tree's responsiveness to environmental changes. Needle turnover rate was found to be most important to accurately model stem growth dynamics. We conclude that leaf area and its adjustment time to new conditions is the main determinant for radial stem growth of pine trees as the transpiring area needs to be supported by a proportional amount of sapwood, despite the growth-inhibiting environmental conditions.
  • Chan, Tommy; Berninger, Frank; Kolari, Pasi; Nikinmaa, Eero; Hölttä, Teemu (2018)
    Current methods to study relations between stem respiration and stem growth have been hampered by problems in quantifying stem growth from dendrometer measurements, particularly on a daily time scale. This is mainly due to the water-related influences within these measurements that mask growth. A previously published model was used to remove water-related influences from measured radial stem variations to reveal a daily radial growth signal (ΔˆGm). We analysed the intra- and inter-annual relations between ΔˆGm and estimated growth respiration rates (Rg) on a daily scale for 5 years. Results showed that Rg was weakly correlated to stem growth prior to tracheid formation, but was significant during the early summer. In the late summer, the correlation decreased slightly relative to the early summer. A 1-day time lag was found of ΔˆGm preceding Rg. Using wavelet analysis and measurements from eddy covariance, it was found that Rg followed gross primary production and temperature with a 2 and 3 h time lag, respectively.This study shows that further in-depth analysis of in-situ growth and growth respiration dynamics is greatly needed, with a focus on cellular respiration at specific developmental stages, its woody tissue costs and linkages to source–sink processes and environmental drivers.
  • Mäkelä, A.; Grace, J. C.; Deckmyn, G.; Kantola, A.; Campioli, M. (2010)
  • Pyörälä, Jiri; Saarinen, Ninni; Kankare, Ville; Coops, Nicholas C.; Liang, Xinlian; Wang, Yunsheng; Holopainen, Markus; Hyyppä, Juha; Vastaranta, Mikko (2019)
    Information on wood properties is crucial in estimating wood quality and forest biomass and thus developing the precision and sustainability of forest management and use. However, wood properties are highly variable between and within trees due to the complexity of wood formation. Therefore, tree-specific field references and spatially transferable models are required to capture the variability of wood quality and forest biomass at multiple scales, entailing high-resolution terrestrial and aerial remote sensing methods. Here, we aimed at identifying select tree traits that indicate wood properties (i.e. wood quality indicators) with a combination of terrestrial laser scanning (TLS) and airborne laser scanning (ALS) in an examination of 27 even-aged, managed Scots pine (Pinus sylvestris L.) stands in southern Finland. We derived the wood quality indicators from tree models sampled systematically from TLS data and built prediction models with respect to individual crown features delineated from ALS data. The models were incapable of predicting explicit branching parameters (height of the lowest dead branch R2 = 0.25, maximum branch diameter R2 = 0.03) but were suited to predicting stem and crown dimensions from stand, tree, and competition factors (diameter at breast height and sawlog volume R2 = 0.5, and live crown base height R2 = 0.4). We were able to identify the effect of canopy closure on crown longevity and stem growth, which are pivotal to the variability of several wood properties in managed forests. We discussed how the fusions of high-resolution remote sensing methods may be used to enhance sustainable management and use of natural resources in the changing environment.