Soil aeration and soil water tension in skidding trails during three years after trafficking
Introduction
Driving on forest soil bears a high risk of causing soil damage due to soil compaction and rutting (Greacen and Sands, 1980, Cambi et al., 2015). This has led to the enforcement of permanent skidding trails by certification agencies (FSC: Forest Stewardship Council, PEFC: Programme for the Endorsement of Forest Certification Schemes) and forest managers (in Germany e.g. MLR, 2003, Bayerische Staatsforsten, 2010). Furthermore threshold values of damage indicators were set up to trigger the cancellation of harvesting activity in case of unacceptable soil damage (Lüscher et al., 2010, AG Bodenschutz, Niedersächsische Landesforsten, 2014, Kremer et al., 2012). In consequence a permanent grid of development lines is laid out comprising of a 4 m wide skidding trail every 20 m, where soil compaction is accepted as a compromise between economic demands and ecological conservation of soil function. Hence parts of ecological soil functions in 20% of the forest area may be sacrificed for economic benefits. Structural soil damage may result from compaction or kneading (rutting). While the lateral and vertical spread of compaction stress can be easily described according to Boussinesq theory (Hillel, 1998), the extension of kneading effects is less predictable. It is connected with the disruption of pore continuity blocking exchange processes in the soil. The total impact of machine trafficking on forest soils is determined by (i) the area which is impacted by driving, (ii) the depth of impact, (iii) the duration/irreversibility of the soil structural damage.
A lateral extension of soil compaction from the wheel track was observed frequently but not in any case (Labelle and Jaeger, 2011, Ampoorter et al., 2010). In particular the middle line between the wheel tracks may be impacted from skidded logs (Dickerson, 1976) but also indirectly from the disturbed wheel tracks (Ampoorter et al., 2010).
Compaction by vehicle driving in forest soil has been observed to range down to 40 cm depth (Riggert et al., 2016). Maximum compaction occurs in 10–30 cm depth (Labelle and Jaeger, 2011, Cambi et al., 2015). But Gaertig et al. (2002) point out, that aeration deficiency rather than compaction is decisive for the soil ecological impact, and this is driven by the gas diffusivity of the uppermost 5 cm of the soil profile.
Observations on the recovery time of compacted wheel tracks in forests range from 3 years (Bekele et al., 2007, Reisinger et al., 1992) to more than 10 years (Dickerson, 1976, Wilpert and Schäffer, 2006, Ebeling et al., 2016) and even more than 70 years (Webb et al., 1986). The wide range of recovery times is due to site specific differences in water regime, clay content and soil biological activity (Cambi et al., 2015, Ebeling et al., 2016).
We hypothesized:
After trafficking the CO2-concentration in soil air ([CO2]) in the upper soil (6 cm) is strongly increased in tracks but not in the middle lane.
[CO2] is related to water filled pore space (WFPS) and soil temperature.
After trafficking there are less macropores and thus more WFPS (measured as lower SWT) in the skid track than in the undisturbed soil.
The nearly unpassed middle lane of the skid trail has a dynamic of soil water tension (SWT) that is similar to the undisturbed soil.
Iron rods reflect the soil aeration difference between wheel tracks, middle lane and undisturbed soil.
Section snippets
Site and skid trails
The investigated site is a 34 year old beech forest from natural regeneration in the Solling. The Solling is a mountain range of Triassic sandstone situated in Lower Saxony, Germany. Elevation of the investigated site is 400 m a.s.l, the mean annual precipitation at a monitoring site on 500 m a.s.l. is 1000 mm. The soils are cambisols from silty Pleistocene deposits (clay 18.6 ± 2.9%, silt 66.5 ± 4.9%, sand 14.9 ± 2.7%, pH(CaCl2) = 3.8–4.2, Corg(0–5 cm) = 86 ± 21 g kg−1) (Fründ et al., unpublished data). The site
Weather
The sum of precipitation at the NWFVA monitoring site was 1009 mm, 1045 mm, 1029 mm in the years 2013, 2014, 2015 respectively. The estimated water balance was positive in every year being 338 mm, 283 mm, 316 mm respectively. Regarding only the time period, when soil water tension and CO2-concentration was analyzed (May 8 to Sept. 10) the sum of precipitation was 377 mm in 2013, 485 mm in 2014, and 328 mm in 2015. The estimated water balance from May 8 to Sept. 10 was negative in the years 2013 and 2015
Discussion
The soil water tension is indicating the drainage of the pore system. There is a characteristic course in the undriven control area. During the winter the pore system is filling up with water. The water is more and more extracted during the progression of the vegetation period (until late summer). In the Solling which is rich in precipitation the water stock in the soil gets only gently stressed in summer (Schipka, 2002). In the year 2014 the field capacity was just reached at the end of the
Conclusions
It can be concluded that for the promotion of soil structure regeneration processes it is important that water is extracted from compacted soil areas. The water extraction of forest trees has a strong contribution to the soil water dynamics. But this seems to fail in the investigated skid trails in the wheel track as well as in the middle lane. In order to promote the soil structure recovery in skid trails the driving impact should be restricted to a level, where tree roots in the middle lane
Acknowledgement
This work was funded by the Ministry of Science and Culture of Lower Saxony, Germany as part of the RÜWOLA-project. We gratefully acknowledge support by the Lower Saxony State Forests (NLF).
References (36)
- et al.
Assessing the effects of initial soil characteristics, machine mass and traffic intensity on forest soil compaction
For. Ecol. Manage.
(2010) - et al.
Soil profile CO2 concentrations in forested and clear cut sites in Nova Scotia, Canada
For. Ecol. Manage.
(2007) - et al.
Impact of heavy traffic on soil macroporosity of two silty forest soils: initial effect and short-term recovery
Geoderma
(2014) - et al.
The impact of heavy traffic on forest soils: a review
For. Ecol. Manage.
(2015) - et al.
Structural recovery in three selected forest soils after compaction by forest machines in Lower Saxony, Germany
For. Ecol. Manage.
(2016) - et al.
Temporal changes in soil pore space CO2 concentration and storage under permanent grassland
Agric. For. Meteorol.
(2007) - et al.
The impact of soil aeration on oak decline in southwestern Germany
For. Ecol. Manage.
(2002) - et al.
Forwarder traffic impacted over at least four years soil air composition of two forest soils in northeast France
Geoderma
(2013) - et al.
Soil CO2 efflux vs. soil respiration. Implications for flux models
Agric. For. Meteorol.
(2011) - et al.
Using iron metal rods to infer oxygen status in seasonally saturated soils
CATENA
(2008)
Bodenschutz bei der Holzernte in den Niedersächsischen Landesforsten
Compaction and rutting during harvesting affect better drained soils more than poorly drained soils on wet pine flats
South. J. Appl. Forest.
Lme4: Linear mixed-effects models using Eigen and S4
Bodenschutz bei den Bayerischen Staatsforsten
Nutrient concentration on skid trails under brush mats - is a redistribution of nutrients possible?
Croat. J. For. Eng.
Carbon dioxide efflux and concentration in two soils under temperate forests
Biol. Fert. Soils
Soil compaction after tree-length skidding in northern Mississippi
Soil Sci. Soc. Am. J.
Soil CO2 concentration and efflux as affected by heavy traffic in forest in northeast France
Eur. J. Soil Sci.
Cited by (19)
Impacts to soil properties still evident 27 years after abandonment in Amazonian log landings
2022, Forest Ecology and ManagementCitation Excerpt :Several studies have shown that emissions between the compacted tracks in skid trails are higher than in the more compacted tracks (Warlo et al., 2019; Vantellingen and Thomas, 2021). In contrast, the natural efflux of CO2 out of the soil may be diminished by heavy compaction underneath the tracks or ruts within skid trails (Fründ and Averdiek, 2016; Shabaga et al., 2017), which may last for decades (Ebeling et al., 2016). Considering post-logging soil emissions, Keller et al. (2005) speculated that if the CH4, CO2 and NOx emissions encountered in their study were similar across other logging sites in Amazonia, the emissions for the Brazilian Amazon would need to be adjusted upward by at least 5%.
Glucose amendment influences restructuring of compacted soil blocks – Results of a field experiment with varying soil-site conditions
2021, Soil and Tillage ResearchCitation Excerpt :In order to assess the soil aeration, the concentration of CO2 in soil air in 5 cm depth was determined in April 2014 with a portable device (Foerster et al., 2012). The CO2-concentration was 0.31 % in the spruce forest soil and 0.62 % in the grassland soil indicating a good soil aeration at both sites (Fründ, 2018; Fründ and Averdiek, 2016). Compacted soil blocks were made from two soil substrates (Table 2).
Soil physio-chemical and biological indicators to evaluate the restoration of compacted soil following reforestation
2019, Ecological IndicatorsCitation Excerpt :Following soil compaction, pore space and its connectivity are generally destroyed. This can hampers the soil-air gas exchange and augment CO2 concentrations (Fründ and Averdiek, 2016; Flores Fernández et al., 2018), which ultimately leads to reduce root growth and density (Gaertig et al., 2002; von Wilpert and Schäffer, 2006; Flores Fernández et al., 2018). Our results revealed that total porosity and macroporosity showed some signs of recovery in the AS, AV, and CS plantations 25 year after planting, but these values were still lower than the values recorded at the CB-QC natural stands.
Ground-based harvesting operations of Pinus taeda affects structure and pore functioning of clay and sandy clay soils
2018, GeodermaCitation Excerpt :Conversely, DC where Mac is 0.10 m3 m−3 was ~88% for soils with 10% clay, 79% for soils with 20–30% clay, and 75% for soils with 30–70% clay (Suzuki et al., 2013). Values of Mac below 0.10 m3 m−3, which is considered as minimum for satisfactory growth and development of plants (Vomocil and Flocker, 1966), quantified after felling and after three passes of the skidder in our study restrict water infiltration and redistribution and gas flux (Epron et al., 2016; Fründ and Averdiek, 2016; Toivio et al., 2017). Reduction in hydraulic conductivity is of significant concern, since low-permeability soils become vulnerable to erosion (Cerdà, 1996; Wagenbrenner et al., 2016).
Long-Term Effects of Timber Extraction by a Crawler Tractor on Soil Condition Recovery in a Mixed Forest
2023, Iranian Journal of Forest