Stem distance as an explanatory variable for the spatial distribution and chemical conditions of stand precipitation and soil solution under beech (Fagus sylvatica L.) trees

Abstract

<p>The partitioning of bulk precipitation (PR) in forest ecosystems and its chemical composition depends on both meteorological factors, such as precipitation amount and intensity, evaporation rate, and wind speed, and stand structural factors, such as stand density, canopy structure, bark texture, and spatiotemporal distribution and density of foliage. We analysed fluxes of water and element contained therein of a mature European beech (<em>Fagus sylvatica</em> L.) forest stand on sandy soils in northeastern Germany. We applied a radially symmetrical setup within a stem distance gradient to measure stand precipitation (SP) with its components of throughfall (TF) and stemflow (SF), as well as to measure soil moisture, the chemical composition of the soil solution, the soil chemistry, and the fine root distribution. The chemical analysis of the constituents covered the macroelements (Ca, Mg, K, Na, Al, Fe, Mn, Si, S, P), the cations and anions NH<sub>4</sub><sup>+</sup>, NO<sub>3</sub><sup>-</sup>, Cl<sup>-</sup>, SO<sub>4</sub><sup>2-</sup>, and a few heavy metals (Cu, Pb, Zn). With an average PR of 620 mm a<sup>-1</sup>, the partitioning resulted in 79% TF, 6% SF, and 15% canopy evaporation. TF volume increased with distance to stem during summer, but decreased during winter. Clear spatial gradients with increasing concentrations from PR, to different classes of TF as the distance from the trunk decreased, to SF were observed for nearly all elements. The contact of precipitation with leaves and the canopy structures alters the chemical composition of TF and SF by transferring elements from dry deposition or leaching of intracellular materials from the canopy and leads to the input of larger amounts of macroelements and heavy metals with the SP into the soil. Spatial patterns of canopy structures thus affect the spatial variation of TF and its constituents, which also affects the spatial distribution of roots and, at least in phases, the chemical composition of the topsoil solution.</p>

Under the canopy: disentangling the role of stemflow in shaping spatial patterns of soil microbial community structure underneath trees

“…( 2021 ) found near‐stem microsites of unique physiochemistry, including increased soil organic C content and macropore proportion, and Jochheim et al . ( 2022 ) found higher macronutrient ion and heavy metal concentrations in soil solutions within the stemflow infiltration area. At a forest site on the Canary Islands, Aboal et al .…”

Dynamics of Soil CO2 Efflux and Vertical CO2 Production in a European Beech and a Scots Pine Forest

“…A possible approach to partitioning R h and R a in forests would be to apply a model based on root allometry as a function of stem distance and tree diameter at breast height (Zhao et al, 2021). Fine roots in the investigated beech stand exhibited a maximum density at a 2.5 m stem distance at 0-30 cm mineral soil depth, but also close to the stem at a 30-60 cm soil depth (Jochheim et al, 2022). Previous researchers have found similar horizontal distribution patterns of fine roots for beech forests and pine forests (Friedrich, 1992;Hölscher et al, 2002;Hornschuch et al, 2007;Hornschuch, 2009;Jurasinski et al, 2012).…”