Black Alder (Alnus glutinosa (L.) Gaertn.) on Compacted Skid Trails: A Trade-off between Greenhouse Gas Fluxes and Soil Structure Recovery?

Abstract

The compaction of forest soils can deteriorate soil aeration, leading to decreased CH4 uptake and increased N2O efflux. Black alder (Alnus glutinosa) may accelerate soil structure regeneration as it can grow roots under anaerobic soil conditions. However, symbiotic nitrogen fixation by alder can have undesirable side-effects on greenhouse gas (GHG) fluxes. In this study, we evaluated the possible trade-off between alder-mediated structure recovery and GHG emissions. We compared two directly adjacent 15-year old beech (Fagus sylvatica) and alder stands (loamy texture, pH 5–6), including old planted skid trails. The last soil trafficking on the skid trails took place in 1999. GHG fluxes were measured over one year. Undisturbed plots with beech had a moderately higher total porosity and were lower in soil moisture and soil organic carbon than undisturbed alder plots. No differences in mineral nitrogen were found. N2O emissions in the undisturbed beech stand were 0.4 kg ha−1 y−1 and 3.1 kg ha−1 y−1 in the undisturbed alder stand. CH4 uptake was 4.0 kg ha−1 y−1 and 1.5 kg ha−1 y−1 under beech and alder, respectively. On the beech planted skid trail, topsoil compaction was still evident by reduced macro porosity and soil aeration; on the alder planted skid trail, soil structure of the uppermost soil layer was completely recovered. Skid trail N2O fluxes under beech were five times higher and CH4 oxidation was 0.6 times lower compared to the adjacent undisturbed beech stand. Under alder, no skid-trail-effects on GHG fluxes were evident. Multiple regression modelling revealed that N2O and CH4 emissions were mainly governed by soil aeration and soil temperature. Compared to beech, alder considerably increased net fluxes of GHG on undisturbed plots. However, for skid trails we suggest that black alder improves soil structure without deterioration of the stand’s greenhouse gas balance, when planted only on the compacted areas.

Natural recovery of skid trails: a review

“…These studies demonstrate that in the evaluation of skid trail recovery, it is prudent to measure multiple soil properties to ascertain if the recovery is complete. Another aspect of skid trail recovery that has received less attention than physical properties is the rehabilitation of chemical properties (Ebeling et al 2017;Neaves et al 2017;Ilintsev et al 2018;Warlo et al 2019;Sohrabi et al 2020). In Malaysia, Malmer et al (1998) encountered contrasting results in two skid trails that were in close proximity to each other (500 m).…”

“…Recent studies continue to demonstrate this amelioration effect in these challenging reforestation environments caused by skid trails. For example, the 1 to 6 cm soil depth of skid trails in Southern Germany, Warlo et al (2019) encountered recovery of bulk density, macro and total porosity in wheel tracks after 15 years in a plantation of black alder (Alnus glutinosa) when compared with untrafficked soil. In Switzerland, Meyer et al (2014b) evaluating this same species found no impediments to root penetration even though skid trail penetration resistance values exceeded 2.5 MPa, which is the threshold for reduced root growth (Greacen and Sands 1980).…”

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

“…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).…”

Long Term Soil Gas Monitoring as Tool to Understand Soil Processes

“…The observed N 2 O concentration profiles at this plot, however, did not show strong gradients and possible emissions or consumption could not be calculated. The N 2 O balance of a forest or agricultural site rather depends on catching the peak events [113,114], than spanning the potentially long time between the peak events when fluxes might be negligible. A regular schedule might thus be a drawback.…”