Söderåsen National Park

From First Hike to a Group Project

Sep 04, 2023

The first hike in Sweden I went on was in Söderåsen National Park, just 50K north of Lund. I went on a trip during orientation week organized by the University for international students. It was great fun. I got to know so many interesting people on the bus ride and on the trail. It was short hike, and more of a stroll through the woods…but nice to get off of campus nonetheless. Last spring, we returned to Söderåsen with my geography class to get some experience doing fieldwork. We had such an excellent time. The weather was freezing. The classic Swedish, cold and wet rain. We had a grand ‘ol time. This is my effort to archive old projects. If you’re curious to hear how my colleagues and I predicted climatic effects might impact Söderåsen (from a geography perspective) then continue reading :) Big shoutout to Matti, Kim, and Xiaoyan for being such kickass teammates.

A CLIMATE-CHALLENGED FUTURE

TEMPORAL AND SPATIAL EXAMINATION OF HOW CLIMATIC CONDITIONS COULD FACILITATE EROSION PROCESSES IN SÖDERÅSEN NATIONAL PARK

INTRODUCTION

Future changes in climatic conditions could impact accessibility of Söderåsen National Park. As a valued recreational area, the park is visited by 400,000 people annually (Steeltech, 2023). Climate change (CC) is expected to impact erosion through changes in temperature, precipitation, and weather patterns (Li & Fang, 2016). Our assessment of erosion is based on Julien's (2010, p. 1) definition as “the motion of solid particles, called sediment”. We predict CC coupled with an increase in tourism will accelerate erosion in Söderåsen. We will provide a brief overview of projected climatic changes in Skåne, a brief methodology of our study, provide key field observations of current erosion processes in Söderåsen, and lastly suggest future sustainable management practices to maintain recreational value of the park.

METHODOLOGY

Our research team synthesized climate projections for precipitation and temperature changes in Skåne according to different Representative Concentration Pathways (RCP 2.6, RCP 4.5 & RCP 8.5) available at the Swedish Meteorological and Hydrological Institute (SMHI) for the projected 2071-2100 period (SMHI, 2023b). Subsequently, we conducted a literature review on the myriad CC implications of erosion. On March 14th 2023 between 12am and 3pm, we collected field notes and photos observing erosion. It had been raining heavily (>10mm/d) the day before, and rained lightly (<3mm/d) on the day of observations; temperature ranged from 1°C to 8°C (SMHI, 2023a). We highlighted four processes facilitating erosion as identified in the sites in Figure 1. Our spatial scale is the Skäralid canyon of Söderåsen. Our temporal scale is 2100, consistent with the scale used in several climate projections (SMHI, 2023b).

Figure 1

BACKGROUND

Climate Projections

According to the SMHI, CC is going to affect both precipitation and temperature in Skåne by 2100. Precipitation is projected to increase by 3-11 mm/m, with days with strong and extreme precipitation events becoming more common by 2-6.5 days and 0.5-3 days, respectively (SMHI, 2023b). Dry periods remain relatively similar to current conditions, only increasing by a day in the highest-warming scenarios (Tables 1 and 2). Changes in annual rainfall, intensity, and the spatiotemporal distribution of rainfall are expected to occur in Skåne (SMHI, 2023b). An increase in precipitation frequency and intensity, through saturation and increased runoff will directly exacerbate erosion potential (Li & Fang, 2016).

Depending on the RCP used, the average temperature is expected to rise by +1–2°C (RCP 2.6), +2–3°C, or +4–4.5 °C, respectively (SMHI, 2023b). Daily maximum and minimum temperatures are projected to increase, with longest heat waves also increasing by up to 30 days. Furthermore, frost days decrease by a range of 30-65 days, increasing the vegetative period to a range of 30-110 days.

Predicted temperature changes in Skåne could impact soil erosion in Söderåsen through direct and indirect processes. Predictions suggest Skåne temperature changes will fluctuate between below and above freezing, showing a greater potential for accelerated physical weathering and soil deterioration (Li & Fang, 2016).

FIELD OBSERVATIONS

Within Söderåsen, slope creep results from a combination of factors, such as rainfall, soil and vegetation types, and slope gradient. This type of erosion gradually detaches the topsoil, causing it to slowly move downward. In Figure 2a, the topsoil is observed to be shifting downwards due to creep less than 50 cm away from the hiking trail. In order to prevent interference with hiking trails, park rangers use wooden boards to support the sliding soil. Furthermore, the shapes of beech trunks on the slope, as seen in Figure 2b, indicate slope creep. This is because beech trees generally grow upright, but as the slope creeps, the trees begin to tilt downhill. This results in the trees adjusting their angle, ultimately causing a bulge to form on the lower part of the trunk.

Figure 2

Another type of erosion we observed was human-induced trampling erosion, caused by numerous people walking on the pathways of the park. Trampling has eroded many of the park’s pathways, specifically the ones located along the slopes of the Skäralid canyon (Figure 3a), eroding the top layer of the fine-fraction covers and leaving them susceptible to being washed out by precipitation. This is especially visible in areas where rain water accumulates and the sediment of the pathways reaches carrying capacity, as footprints can be seen in Figure 3d. Furthermore, we identified several instances of tree roots having become exposed as a result of people trampling over them (Figure 3c).

Figure 3

We also observed several instances of windthrow of beech trees uprooted by the wind, particularly in depressions on steep slopes and on the southern ridge along Skäralid canyon (Figure 4a). The windthrows left behind circular cavities, exposing underlying soils to the elements. Around the cavity, the regolith starts to erode and water seeps in (Figure 4b). Compared to the surrounding trees, the uprooted ones were particularly tall specimens whose crowns had likely reached the canopy. Some of the windthrows took down smaller surrounding trees, creating small clearings.

Fluvial erosion, the detachment of riverbed sediments, is documented in Figure 5 (Bogaart et al., 2003). In Figure 5a there is evidence of fluvial erosion on the sides of the riverbed and Figure 5b illustrates evidence of fluvial erosion undercutting the stream bank and the adjacent trail.

DISCUSSION

In summary, our observations coupled with climate forecasts have various future implications for Söderåsen. The slope creep has implications for potential environmental damage and safety hazards. As projected rainfall increases, surface runoff and flow will increase, which will also cause pore water pressure changes (Bračko et al., 2022). Additionally, increasing temperature could contribute to the development of cracks and fissures on the slopes (Yue et al., 2022). All these factors can result in increased soil instability and slope creep, leading to higher risks of damage to tourist facilities (Bračko et al., 2022). Furthermore, the sediment could contaminate or block the river, leading to environmental damage.

Trampling erosion has implications for both future recreational use of the park and conservation practices required. Evidence shows frequent visitation is a major contributor to erosion in national parks (Fidelus-Orzechowska et al., 2021). As precipitation is projected to increase with heavy precipitation events becoming more frequent, the trampled pathways are at increased risk of erosion. Coastal erosion in Skåne may exacerbate this effect, as it may threaten coastal recreation areas and bring more visitors to Söderåsen.

Windthrows have implications for future vegetation and erosion dynamics. CC will enhance the competitive advantage of European beech at its northern border in Skåne as beech is more tolerant to changes in climate-related abiotic factors (e.g. drought and heat) than boreal species (Bolte et al., 2010). Whereas the decrease in frost days will extend the growing season (Tyler et al., 2018), the lifespan of beech decreases steeply with increasing temperatures (Di Filippo et al., 2015). As higher temperatures accelerate tree growth, the trees grow taller but wood density decreases making them more susceptible to wind action. Likewise fewer frosts reduce tree root anchorage exacerbating tree mortality by windthrow in Söderåsen (Jönsson et al., 2015). These blowdowns will likely occur more frequently in the future. The regolith around the root plates and pits will become dislodged and root anchorage lost, creating large disturbances with unconsolidated regolith susceptible to erosion from the increased heavy rainfalls (Constantine et al., 2012).

Predicted temporal and spatial changes in intensity, frequency, and distribution of precipitation will impact fluvial erosion, altering the stream geomorphology and accessibility of the walkways for tourism (Bogaart et al., 2003). In 2100, the walking paths will be weathered regardless, but current climate forecasts suggest further changes to the location of the paths.

CONCLUDING REMARKS

Future Management Approaches

Based on the evidence, we support future management approaches to reduce the impact of CC and mitigate the impacts of processes facilitating erosion. In a Strategy for Sustainable Tourism published in November of 2019, it was suggested Söderåsen reduce visitation and provide more information and guidance for visitors on how to responsibly use the park. Additional thought can go towards intentional trail design, building, stabilization, and routine maintenance slowing the processes facilitating erosion. To combat trampling erosion, and to protect the eroding forest and the slopes, pathways may need to be relocated to more stable locations. The eroding pathways may require further reinforcing.

Limitations and Future Studies

We aimed for objectivity in observing erosion processes in the landscape of Söderåsen, yet confirmation bias may have influenced the four processes we identified in the field. Future studies could have more systematic spatial and temporal rigor by assessing the trails used most frequently. This could enhance Söderåsen’s sustainable tourism practices, increasing resilience and adaptive capacities to the predicted climate-related changes for the park.

GROUP CONTRIBUTIONS

Name

Contributions

Matti Myllynen

Sourced climate projection data for precipitation, helped plan the report structure, wrote ¼ of the report (projections, trampling erosion), planned the introduction together with everyone, took photos of trampling erosion, geolocated half of the photos used, did several edits on the paper to, worked with the grading rubric, helped make the presentation.

Julia Roellke

Provided group organization with meeting agendas, check-ins, synthesis of field notes, paper outline, and presentation. Took the lead on research on the relationship between climate change and erosion. Wrote sections on water erosion and future predictions, future management practices, and limitations to study. Contributed to the introduction, background, and conclusion. Supported overall editing of the paper for formatting and flow etc.

Kim Wölper

Brief literature review on climate change impacts on deciduous broadleaf (especially beech) forests and vegetation-related erosion processes. Wrote field notes which helped us identify 4 erosion examples around which the report is structured, and identified some future implications for landscape changes and uses of the national park.

Took photos of vegetation damage and deformities. Wrote the report sections on observations and discussion of vegetation dynamics and associated impacts on future erosion. Contributed to the introduction, future management approaches, editing, and referencing.

Xiaoyan Kong

Sourced climate projection data for temperature. Wrote the field observation and discussion parts for slope creep. Made the tables and figures of the map. Helped organize the figures and geolocated the photos. Took photos of erosion sites.

The best time working with these folks. From left to right, Kim, Mati, Xiaoyan, me!

REFERENCES

Bogaart, P. W., Balen, R. T. V., Kasse, C., & Vandenberghe, J. (2003). Process-based modelling of fluvial system response to rapid climate change—I: Model formulation and generic applications. Quaternary Science Reviews, 22(20), 2077–2095. https://doi.org/10.1016/S0277-3791(03)00143-4

Bolte, A., Hilbrig, L., Grundmann, B., Kampf, F., Brunet, J., & Roloff, A. (2010). Climate change impacts on stand structure and competitive interactions in a southern Swedish spruce–beech forest. European Journal of Forest Research, 129(3), 261–276. https://doi.org/10.1007/s10342-009-0323-1

Bračko, T., Zlender, B., & Jelušič, P. (2022). Implementation of climate change effects on slope stability analysis. Applied Sciences, 12(16), Article 8171. https://doi.org/10.3390/app12168171

Constantine, J. A., Schelhaas, M.-J., Gabet, E., & Mudd, S. M. (2012). Limits of windthrow-driven hillslope sediment flux due to varying storm frequency and intensity. Geomorphology, 175–176, 66–73. https://doi.org/10.1016/j.geomorph.2012.06.022

Di Filippo, A., Baliva, M., Dinella, A., Schirone, B., Piovesan, G., Pederson, N., Brunetti, M., Kitamura, K., & Knapp, H. D. (2015). The longevity of broadleaf deciduous trees in Northern Hemisphere temperate forests: Insights from tree-ring series. Frontiers in Ecology and Evolution, 3(May), Article 46. https://doi.org/10.3389/fevo.2015.00046

Fidelus-Orzechowska, J., Gorczyca, E., Bukowski, M., & Krzemień, K. (2021). Degradation of a protected mountain area by tourist traffic: Case study of the Tatra National Park, Poland. Journal of Mountain Science, 18(10), 2503–2519. https://doi.org/10.1007/s11629-020-6611-4

Jönsson, A. M., Lagergren, F., & Smith, B. (2015). Forest management facing climate change—An ecosystem model analysis of adaptation strategies. Mitigation and Adaptation Strategies for Global Change: An International Journal Devoted to Scientific, Engineering, Socio-Economic and Policy Responses to Environmental Change, 20(2), 201–220. https://doi.org/10.1007/s11027-013-9487-6

Julien, P. Y. (2010). Erosion and Sedimentation (2nd ed.). Cambridge University Press. https://doi.org/10.1017/CBO9780511806049

Li, Z., & Fang, H. (2016). Impacts of climate change on water erosion: A review. Earth-Science Reviews, 163, 94–117. https://doi.org/10.1016/j.earscirev.2016.10.004

SMHI. (2023a). Fördjupad Klimatscenariotjänst. [Visited on 10.3.2023, accessed at

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SMHI. (2023b). Väder i Skäralid, Klippan. [Visited on 13.3.2023, accessed at