Does Mixing Tree Species Affect Water Storage Capacity of the Forest Floor? Laboratory Test of Pine-Oak and Fir-Beech Litter Layers

Abstract

During the last decade, tree species mixing has been widely supported as a silvicultural approach to reduce drought stress. However, little is known on the influence of tree species mixing on physical properties and the water storage capacity of forest soils (including the forest floor). Thus, the study aimed to analyze the effect of mixing pine needles and oak leaves and mixing fir needles and beech leaves on hydro-physical properties of the litter layer during laboratory tests. We used fir-beech and pine-oak litter containing various shares of conifer needles (i.e., 0, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90 and 100%) to determine the influence of the needle admixture on bulk density, total porosity, macroporosity, water storage capacity, the amount of water stored in pores between organic debris and the degree of saturation of mixed litter compared to broadleaf litter (oak or beech). We found that the admixture of fir needles increased the bulk density of litter from 7.9% with a 5% share of needles to 55.5% with a 50% share (compared to pure beech litter), while the share of pine needles < 40% caused a decrease in bulk density by an average of 3.0–11.0% (compared to pure oak litter). Pine needles decreased the water storage capacity of litter by about 13–14% with the share of needles up to 10% and on average by 28% with the 40 and 50% shares of pine needles in the litter layer. Both conifer admixtures reduced the amount of water stored in the pores between organic debris (pine needles more than fir needles).

Potential for significant precipitation cycling by forest‐floor litter and deadwood

“…Similarly, several previous studies have also found that broadleaf litter had a larger storage capacity compared to needle litter. Walsh and Voigt (1977), Sato et al (2004) Li et al (2013 and Ilek et al (2021) found that the storage capacity per unit dry weight of broadleaf litter was higher than that of needle litter by factors of up to 1.6, 1.8, 2.65 and 1.4 respectively. In general, the larger storage capacity in broadleaf litter compared to needle litter can be related to structural differences between the two litter types (Klamerus-Iwan et al, 2020;Li et al, 2013).…”

“…Laboratory experiments on forest litter samples have been conducted to quantify their water storage properties (e.g. Guevara‐Escobar et al, 2007; Ilek et al, 2021; Li et al, 2013; Putuhena & Cordery, 1996; Sato et al, 2004; Walsh & Voigt, 1977). Fewer studies (to our knowledge) have measured the water retention capacity of litter in situ (e.g.…”

Potential for significant precipitation cycling by forest-floor litter and deadwood

“…Similarly, several previous studies have also found that broadleaf litter had a larger storage capacity compared to needle litter. Walsh & Voigt (1977), Sato et al, (2004) Li et al (2013), and Ilek et al (2021) found that the storage-capacity per unit dry weight of broadleaf litter was higher than that of needle litter by factors of up to 1.6, 1.8, 2.65, and 1.4 respectively. In general, the larger storage capacity in broadleaf litter compared to needle litter can be related to structural differences between the two litter types (Klamerus-Iwan et al, 2020;Li et al, 2013).…”

“…Whereas canopy interception losses have been characterized across numerous forest sites (Yue et al, 2021), only a few previous studies have evaluated the storage and retention capacity of the forest-floor litter layer, and most of these studies have been focused on the leaf component (e.g., Gerrits and Savenije, 2011;Klamerus-Iwan et al, 2020). Laboratory experiments on forest litter samples have been conducted to quantify their water storage properties (e.g., Walsh and Voigt, 1977;Putuhena and Cordery, 1996;Sato et al, 2004;Guevara-Escobar et al, 2007;Li et al, 2013;Ilek et al, 2021). Fewer studies (to our knowledge) have measured the water retention capacity of litter in situ (e.g., Brechtel, 1969;Thamm and Widmoser, 1995;Schaap and Bouten, 1997;Gerrits et al, 2007).…”

Potential for significant precipitation cycling by forest-floor litter and deadwood

“…Whereas canopy interception losses have been characterized across numerous forest sites (Yue et al, 2021), only a few previous studies have evaluated the storage and retention capacity of the forest-floor litter layer, and most of these studies have been focused on the leaf component (e.g., Gerrits and Savenije, 2011;Klamerus-Iwan et al, 2020). Laboratory experiments on forest litter samples have been conducted to quantify their water storage properties (e.g., Walsh and Voigt, 1977;Putuhena and Cordery, 1996;Sato et al, 2004;Guevara-Escobar et al, 2007;Li et al, 2013;Ilek et al, 2021). Fewer studies (to our knowledge) have measured the water retention capacity of litter in situ (e.g., Brechtel, 1969;Thamm and Widmoser, 1995;Schaap and Bouten, 1997;Gerrits et al, 2007).…”