Hygroscopicity of the bark of selected forest tree species

Abstract

As the outer layer of trees and shrubs, bark is exposed to the direct action of atmospheric conditions and reacts to changes in relative air humidity. This study focuses on the actual hygroscopicity of the bark, regarded as a component of the total bark retention capability. The main research aims were to: (1) determine the physical properties (specific density, bulk density, total porosity), actual hygroscopicity and maximum water storage capacity of the stem bark at breast height (1.3 m) of eight forest tree species; (2) assess the relationship between bark actual hygroscopicity and its physical properties; (3) determine the share of the actual hygroscopicity of bark in its maximum water storage capacity. Significant differences were observed among the different species considered as a consequence of the variation in physical properties of their bark. Actual hygroscopicity of bark (expressed in balance units), i.e., the maximum water amount that can be absorbed from saturated air by the outer bark layer, showed a significant relationship with bark physical properties. Depending on tree species, actual hygroscopicity may constitute from 10 to 30% of the maximum water storage capacity of bark.

Drought responses and their effects on radial stem growth of two co-occurring conifer species in the Mediterranean mountain range

“…Güney et al (2015) investigated xylogenesis of C. libani from the same area during 2013 and stated the growth cessation to take place at the end of September, but sampling was performed until the end of October only and the winter months were not explored. However, there are also some reservations to be considered with dendrometer measurements in general (Drew and Downes 2009;Ilek et al 2016) and with the zero-growth concept (Zweifel et al 2016) in particular. The zero-growth concept assumes no growth during periods of stem shrinkage which appears to be physiologically reasonable (Hinckley and Lassoie 1981;Hsiao et al 1976;Lockhart 1965).…”

Rainfall interception and redistribution by a common North American understory and pasture forb, <i>Eupatorium capillifolium</i> (Lam. dogfennel)

“…Even the maximum stem water storage capacity is of a similar magnitude to values reported by past work on woody plants, 0.2-5.9 mm (Klamerus-Iwan et al, 2020), albeit at the lower end of the range. Most current research on stem water storage D. A. R. Gordon et al: Rainfall interception and redistribution by a common North American understory has focused on intrinsic factors of woody plant stems, like bark thickness, porosity, microrelief or roughness (Ilek et al, 2017;Levia and Herwitz, 2005;Levia and Wubbena, 2006;Sioma et al, 2018;Van Stan et al, 2016;Van Stan and Levia, 2010); however, other stem structures besides bark may be capable of storing substantial water, e.g., the desiccated leaves of our study plant. There were differences in how gross rainfall was redistributed by the overstory canopy compared with how modeled overstory throughfall was redistributed by the dogfennel understory.…”

Bark water storage capacity influences epiphytic orchid preference for host trees

“…Our analysis also found a close association between microrelief characteristics and bark water storage; species preferred by orchids had higher water‐retention capacity, consistent with a previous study (Callaway et al., ). Water‐storage capacity, determined by bark porosity, affects bark hygroscopicity, which is a significant component of water balance in forest ecosystems, especially for epiphytes (Johansson, ; Ilek et al., ). Barks with high porosity and WRC can be found in a wide range of phorophyte species.…”