Evaluating Soil–Root Interaction of Hybrid Larch Seedlings Planted under Soil Compaction and Nitrogen Loading

Abstract

Although compacted soil can be recovered through root development of planted seedlings, the relationship between root morphologies and soil physical properties remain unclear. We investigated the impacts of soil compaction on planted hybrid larch F1 (Larix gmelinii var. japonica×L. kaempferi, hereafter F1) seedlings with/without N loading. We assumed that N loading might increase the fine root proportion of F1 seedlings under soil compaction, resulting in less effects of root development on soil recovery. We established experimental site with different levels of soil compaction and N loading, where two-year-old F1 seedlings were planted. We used a hardness change index (HCI) to quantify a degree of soil hardness change at each depth. We evaluated root morphological responses to soil compaction and N loading, focusing on ectomycorrhizal symbiosis. High soil hardness reduced the total dry mass of F1 seedlings by more than 30%. Significant positive correlations were found between HCI and root proportion, which indicated that F1 seedling could enhance soil recovery via root development. The reduction of fine root density and its proportion due to soil compaction was observed, while these responses were contrasting under N loading. Nevertheless, the relationships between HCI and root proportion were not changed by N loading. The relative abundance of the larch-specific ectomycorrhizal fungi under soil compaction was increased by N loading. We concluded that the root development of F1 seedling accelerates soil recovery, where N loading could induce root morphological changes under soil compaction, resulting in the persistent relationship between root development and soil recovery.

A Meta‐analysis of the effects of ground‐based extraction technologies on fine roots in forest soils

“…With these criteria, 19 papers (DeArmond et al, 2022; Ebeling et al, 2017; Flores Fernández, Hartmann, & von Wilpert, 2019; Flores Fernández, Rubin, et al, 2019; Högberg & Wester, 1998; Jourgholami, Feghhi, Picchio, et al, 2021; Jourgholami, Feghhi, Tavankar, et al, 2021; Jourgholami, Ghassemi, & Labelle, 2019; Jourgholami, Ramineh, et al, 2019; Malo & Messier, 2011; Meyer et al, 2014; Rygiewicz et al, 2004; Schäffer, 2022; Schäffer et al, 2009; Stutz et al, 2017; Sugai et al, 2020; Warlo et al, 2019, 2022; Watson & Kelsey, 2006) that generated 217 couple comparisons were finally included in the database for the meta‐analysis (Figure 1).…”

“…Finally, we examined the 30 remaining studies applying the following inclusion criteria: i) the study must provide a control treatment which consists of soil not affected by machine passage located close to the analysed skid trail/strip road; ii) the experiment must be set up in a forest stand, nursery studies are also included but they have to be clearly related to a forest context. With these criteria, 19 papers (DeArmond et al, 2022;Ebeling et al, 2017;Flores Fernández, Rubin, et al, 2019;Högberg & Wester, 1998;Jourgholami, Ghassemi, & Labelle, 2019;Jourgholami, Ramineh, et al, 2019;Malo & Messier, 2011;Meyer et al, 2014;Rygiewicz et al, 2004;Schäffer, 2022;Schäffer et al, 2009;Stutz et al, 2017;Sugai et al, 2020;Warlo et al, 2019Warlo et al, , 2022Watson & Kelsey, 2006) that generated 217 couple comparisons were finally included in the database for the meta-analysis (Figure 1).…”

“…Given the abovementioned variability reported in the previous studies and the important role of fine roots within the forest soil system, it is imperative that more information is collected for a deeper understanding in the effects of disturbance (Meyer et al, 2014; Sugai et al, 2020; Watson & Kelsey, 2006). It is also worthy of acknowledging that few studies deal with this topic in comparison to the amount of studies conducted on other forest soil features (Schäffer, 2022).…”

Impacts of wood extraction on soil: assessing rutting and soil compaction caused by skidding and forwarding by means of traditional and innovative methods

“…Ground-based logging operations can negatively affect soil physical characteristics, reducing porosity while also increasing bulk density and resistance to mechanical penetration (Siegel-Issem et al 2005;D'Acqui et al 2020;Lee et al 2020). Moreover, soil compaction indirectly influences tree growth and regeneration due to both physical root damage and reduced soil permeability (Cambi et al 2018a(Cambi et al , 2018bJansson and Wasterlund 1999;Mariotti et al 2020;Sirén et al 2013;Solgi et al 2019;Sugai et al 2020), which may lead to deficiencies of oxygen, water and/or nutrients (Batey 2009;Lee et al 2020) with recovery processes that may take several decades (Bottinelli et al 2014;Jourgholami et al 2020). Rutting and other soil disturbances can also disperse pathogenic fungi, alter microbiological processes (Frey et al 2009;De Wit et al 2014;Cambi et al 2017) and mobilize heavy metals due to the increase in surface water flow (Frey et al 2009;De Wit et al 2014;Eklöf et al 2014).…”

Adaptation of the Root System to the Environment

“…These authors highlighted how, in the medium term and within the adopted size range, the fine root system can recover to pre-harvest conditions in terms of standing biomass and morphological traits. Sugai et al [22] evaluated the impact of soil compaction and N loading on hybrid larch (Larix gmelinii var. japonica × L. kaempferi) seedling roots.…”