Links between phenology and ecophysiology in a European beech forest

Abstract

© iForest -Biogeosciences and Forestry IntroductionAt scales ranging from organ to ecosystem, many processes, particularly those related to carbon cycling (productivity and growth), water (evapotranspiration and runoff), and nutrients (decomposition and mineralization), are directly mediated by phenology (Gu et al. 2003). Spring bud burst provides a particularly good example, as it involves various interactions between trees and the environment. The initiation of this phenological phase depends on early spring air and soil temperatures (Menzel 2000, Lupi et al. 2012 as well as other environmental attributes such as photoperiod (Wareing 1953, Basler & Körner 2012, precipitation and tree health. In turn, the seasonal cycle of leaf development determines many crucial aspects of forest canopy function, including photosynthetic uptake, radiation extinction, rainfall interception, and evapotranspiration (Bonan 1993, Saigusa et al. 2002. Foliage development, assessed at the stand level in terms of the leaf area index (LAI), typically increases rapidly in western European deciduous forests, from early May to mid-July, with the maximum around midJuly (Mussche et al. 2001). LAI affects the transmittance of photosynthetically active radiation (PAR) to the understory. Additionally, leaf development yields increases in transpiration (Střelcová et al. 2006).Tree phenology is dependent on the plant's storage and consumption of carbohydrates (Michelot et al. 2012). These are stored in all organs (i.e., leaves, branches, roots, and stems) in different concentrations, which can vary during the growing season based on the relative rates of production and use (Scartazza et al. 2013). New photoassimilates transported in phloem sap may be used for radial growth, with leaf phenology (i.e., budburst, leaf development and yellowing) thus influencing intra-annual wood formation (Čufar et al. 2008, Sass-Klaassen et al. 2011. The time lags between leaf and xylem growth phenologies vary among species, leading to differences in relative carbon allocation. In deciduous species, budburst generally occurs following radial growth for ring-porous species, whereas for diffuse-porous species, cambial division and consequent radial growth are initiated at almost the same time as budburst (Suzuki et al. 1996, Schmitt et al. 2000, Čufar et al. 2008. Nevertheless, even in diffuse-porous species, onset of cambial activity is sustained to a large degree by carbon accumulated in storage pools (Dietze et al. 2014).Given sufficient soil water and based on atmospheric evaporative demand, maximal transpiration rates occur when trees have full foliage (Meier & Leuschner 2008). However, numerous laboratory experiments on herbaceous plants and tree seedlings or saplings have shown that leaf coloring and leaf area reduction (i.e., events marking onset of particular phenological stages) are common responses to soil water shortage (Löf & Welander 2000). Loss of leaves results in a decrease of the transpiring surface area, avoiding a severe reduction of cell water p...

Combining Dendrometer Series and Xylogenesis Imagery—DevX, a Simple Visualization Tool to Explore Plant Secondary Growth Phenology

“…This has been demonstrated in the case study loaded in DevX. Studies where both approaches, dendrometer, and histological measurements are combined are still scarce, mostly focusing on conifers in temperate (Michelot et al, 2012;Cuny et al, 2015;Urban et al, 2015), Mediterranean (Camarero et al, 2009;Linares et al, 2009; Vieira et al, 2014a,b;Pacheco et al, 2016;Güney et al, 2017), and boreal forests (Chan et al, 2016) or mountain ranges (Ziaco and Biondi, 2016). Some examples of the use of band dendrometers and xylogenesis analysis in the tropics also exist (Mendivelso et al, 2016).…”

“…Considering work performed outside this area, most studies where both monitoring methods are applied have found a delay in wood formation phenological phases, when compared to dendrometer records (Mäkinen et al, 2008;Michelot et al, 2012;Güney et al, 2017), which might be partly ascribed to differentiation and production of phloem (e.g., Gričar et al, 2009Gričar et al, , 2016. Urban et al (2015), although not comparing growth curves of both monitoring approaches, found that the growth begin in dendrometers coincided with histological observations in a pure beech forest. In conifers, according to Mäkinen et al (2008), growth dynamics can systematically lag more than a week behind for microcores when compared to dendrometer records.…”

“…Some examples of the use of band dendrometers and xylogenesis analysis in the tropics also exist (Mendivelso et al, 2016). Even fewer studies compare microcore samples and dendrometer records of the same tree (Michelot et al, 2012;Cuny et al, 2015;Urban et al, 2015;Ziaco and Biondi, 2016;Güney et al, 2017). Comparisons of the methodological approaches for detecting phenological phases on cumulative stem-radius variations have been performed in several data analysis methods by Korpela et al (2010), although none of the widespread sigmoid models were tested (i.e., Gompertz, Weibull, and logistic functions).…”

Drought and irrigation affect transpiration rate and morning tree water status of a mature European beech (Fagus sylvatica L.) forest in Central Europe

“…The upscaling of the tree sap flow to the forest stand level was performed using the regression between the tree diameter at 1.3 m (DBH) and the corresponding sap flow (Čermák et al, ; Urban et al, ). First, the DBHs of all trees of the experimental plot (608 m 2 ) were measured, and based on these values, the trees were divided into the diameter classes (with a step of 3 cm).…”

Trees and seasonal wind gust maxima in Ireland: acclimation and minimal factors of safety

“…For temperate tree species, this begins in spring and tails off in late summer. Most studies indicate that for temperate trees, the length of growing season as regards radial growth is 60-100 days, with cessation occurring in most trees during July or August (Schmitt et al, 2016;Studhalter, Glock, & Agerter, 1963;Urban et al, 2014). Castillo et al (2016), however, compared the phenology of xylem formation in Fagus sylvatica and Pinus sylvestris at various locations in Europe with differing altitudes.…”