An integrated method for high-resolution definition of new diameter-based fine root sub-classes of Fagus sylvatica L.

Abstract

& Key message Compared to the traditional approach, applying micrometric image analysis to fine root samples of Fagus sylvatica with subsequent data treatment through principal component and cluster analysis yielded specific diameter sizes for fine root sub-classes having better resolution of the corresponding branching orders, and a more coherent relationship with the values of annual production and turnover rate. & Context Fine root traits are poorly understood, impeding an accurate representation of terrestrial biogeochemical models. Traditionally used, arbitrary diameter thresholds lead to a misestimation of fine root traits such as branching order, environmental relationship, annual production, and turnover rate. & Aims Here, we present, as modification of the traditional method, an integrated approach to segregate, at high-resolution, fine root populations of Fagus sylvatica into new diameter sub-classes that better correspond with the traits mentioned above. & Methods Samples, collected with a sequential soil coring method, were subjected to a micrometric image analysis, and resultant data were treated with principal component and cluster analysis. & Results Results showed that fine roots were distributed into diameter-size sub-classes (0-0.3 mm, 0.3-1 mm, and 1-2 mm) different from those determined by traditional methods (0-0.5 mm, 0.5-1 mm, and 1-2 mm). New sub-classes provided a better resolution of the corresponding branching-orders, and the values of annual production and turnover rate were more coherent with diameter class and soil depth. Moreover, new sub-classes provided a more precise match with soil temperature than traditional methods. & Conclusion Our method may help to unveil fine root dynamics and development, reduce data analysis time, and make the diameter-based classification more precise and trustworthy even in the case of non-intact samples.

Effect of Essential Nutrients on Roots Growth and Lifespan of Huanglongbing Affected Citrus Trees

“…The double peaks of root growth were the manifestation of the completion of the above-ground biomass of the trees and the beginning of more resource allocation to the root system. Previous studies indicated that the peak of root growth patterns was partly attributed to the phenology of the trees [27,30] in response to soil moisture, nutrient acquisitions, and other growth-promoting factors [7,17,27].The current study indicated that the trees Ca and Ca and Mg combined nutrients had a positive impact on the FRLD dynamics; while Mn and Zn had also a significant effect on FRLD with emphasis on root-zone soil pH management. The decline in FRLD and yield was partly attributed to HLB-induced damage of fine roots, which led to vulnerability to other biotic and abiotic stresses [1,12,15].…”

“…Ca nutrition for trees budded on Cleo and Ca and Mg combined nutrient treated trees budded on Swc rootstocks significantly improved the FRLD of fine roots d > 1 mm. The variation in FRLD density was associated with the growth flush growth stage [7,17,29], moisture [16,17,30], and fertilization [17,29].…”

“…The monthly FRLD data were grouped based on traditional root classification: fine roots (d < 2 mm) and coarse root (d > 2 mm). The fine roots were also divided into three sub-class (<0.5 mm, 0.5-1, and 1-2) [30,47]. The yearly average root data were regrouped into three seasons: spring (Jan.-May), summer (Jun.-Sep.), and fall (Oct.-Dec.) for analysis.…”

Root exudation of mature beech forests across a nutrient availability gradient: the role of root morphology and fungal activity

“…Menzel & Fabian, 1999;Jeong et al, 2011). The average biomass of finest roots <1 mm was estimated from the fine root biomass measured for the organic layer and top mineral soil (see subchapter on 'Root morphology and root biomass' section below) and the distribution of beech fine roots into diameter subclasses according to Montagnoli et al (2018) (59% of fine roots in <1 mm class).…”

Gap Size in Hyrcanian Forest Affects the Lignin and N Concentrations of the Oriental Beech (Fagus orientalis Lipsky) Fine Roots but Does Not Change Their Morphological Traits in the Medium Term

“…Fine root form and function may differ among branching orders [38,39] and the shortcomings of the diameter-based approach are widely recognized [40]. Therefore, in this study, the size class approach was maintained for a better discrimination between the <0.5 mm diameter class (i.e., very fine roots), which represent the most dynamic component of the root system, and the 0.5-1 and 1-2 mm diameter classes, which represent the more stable and woodier portion [41][42][43].…”