SSS7.1

In a large-scale restoration project, we studied the spontaneous vegetation development after the elimination of landscape scars in a former military training area in Hortobágy National Park, Central Hungary. After the removal of approximately 40,000 unexploded ordnances the bomb-craters have been soil-filled, leaving large unvegetated surfaces on a total area of 4,000 hectares in 2017. These research settings provided a unique opportunity to study the effects of environmental heterogeneity on vegetation recovery in a study system, where soil salt content and micro-topography are the major drivers of vegetation patterns. Due to the mixing of soil layers, there were patches with extremely high salt content on the recovering surfaces and several red-listed halophyte plant species, established from the seed bank already in the first year after restoration. We found that the diversity of plant species was the largest in the first year. We detected a significant increase in the vegetation cover and the cover of perennial species from the first year to the second. In the subsequent years the recovery of the vegetation continued but slowed down from the second to the third year. By eliminating landscape scars, the restoration project was successful in increasing the area of alkaline grasslands at the landscape scale and providing grazing lands for local farmers.

How to cite: Valkó, O., Borza, S., Godó, L., Lukács, K., Kiss, R., Kelemen, A., Miglécz, T., Tóth, Á., and Deák, B.: Restoration of landscape scars in former military areas: vegetation recovery in relation to fine-scale environmental heterogeneity, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-667, https://doi.org/10.5194/egusphere-egu21-667, 2021.

If not carefully managed, use of saline and sodic irrigation waters, a common practice in dryland regions, has the potential to cause significant harm to soils. Application of saline and sodic irrigation waters can lead to reductions in hydraulic conductivity, Ks, the mechanisms of which (e.g., slaking, swelling, clay dispersion) have been the focus of a vast body of scientific literature. The rehabilitation process, by contrast, is far less understood. Despite experimental evidence showing a significant degree of irreversibility, traditionally models have treated the degradation and rehabilitation processes as reversible. We demonstrate how this assumption obfuscates our ability to analyze the risk of long-term degradation and to estimate the resources and time required to rehabilitate. We achieve this by using the SOTE model — a minimalistic model that can be used to study dynamics of soil water content, salinity, and sodicity, as driven by irrigation practices and climatic conditions. Crucially, SOTE also accounts for the feedback between changing salinity and sodicity and soil Ks. This feedback includes irreversible changes in hydraulic conductivity, such that a soil’s history of degradation and rehabilitation informs its future state. We compare SOTE to existing models, which do not include hysteresis in Ks, and demonstrate that SOTE predicts more gradual rehabilitation of degraded soils, in line with the limited experimental evidence that has examined this question. For the test case of a degraded soil in a typical Mediterranean climate, SOTE forecasts that rehabilitation requires 50% more time and water resources, in comparison to models without hysteresis. This difference underscores the need to limit the risk of potential degradation, which SOTE also shows increases by 50% when hysteresis is accounted for. A sensitivity analysis indicates that SOTE is most sensitive to parameters connected to soil texture. The sensitivity analysis further indicates that our results are robust -- under all ranges of parameter values SOTE continues to forecast greater time requirements for rehabilitation and increased risk of soil degradation.

How to cite: Kramer, I., Bayer, Y., and Mau, Y.: Rethinking Rehabilitation: Application of the SOTE model to soil rehabilitation following salinity and sodicity induced degradation, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-5085, https://doi.org/10.5194/egusphere-egu21-5085, 2021.

Given that mining sites, active or closed, represent almost 1 percent of Earths’ surface, the choice of adequate rehabilitation strategy is of crucial importance. In our previous work, we were examining the types of rehabilitation and biodiversity developed in consequence, and suggested that natural succession should be favoured whenever possible.

As advocated by IPBES, in its report of the second session of the plenary meeting (2012), indigenous and local knowledge should be valued and taken into account in decision-making processes, in order to stop the biodiversity loss. Yet, the decisions on rehabilitations are being taken by environmental professionals, without consulting with site managers. In this study, we were examining whether there is a local knowledge, which could be used when choosing the adequate rehabilitation technique. We were interested in how quarries and sand and gravel pits managers apprehend biodiversity, since they are the ones conducting actions impacting biodiversity. We were interested in their apprehension of their own actions and its consequences on biodiversity.

Managers of 46 quarries and sand and gravel pits were interviewed, on site, using Critical Incident Technique (Flanagan, 1954), in order to obtain examples of concrete situations showing their relationship with biodiversity as well as their degree of conscience on biodiversity issues. Every interview lasted about one hour and a half and consisted of two parts: the first where general questions were asked in the office for about 15 minutes and the second where the questions about the situations related to biodiversity were asked, during the walk around the site for better contextualization.

We analyzed the collected data using Grounded Theory (Glaser et al. 1967) which is a method used to analyze the field data (e.g. interviews), in order to obtain a theory that explains the underlying phenomenon. Often used in social sciences in order to understand the phenomena and identify the paradigms, this method was well adapted to reveal the causes and motivations of actions conducted by site managers.

Results of this study allowed us to comprehend the site managers as not just actors at the source of impact on biodiversity, but also as actors that are informed and that invest themselves in a relationship with nature. They perceive the value of biodiversity in quarries and gravel pits, conduct a lot of non-mandatory actions for biodiversity, during the life cycle of the site and are motivated to conduct additional measures in order to favor biodiversity. We discovered that there is a hidden expertise among site managers. For instance, they are capable of recognizing a lot of animal species present on site and even to predict the failure of certain rehabilitation techniques.

Following this conclusion, it seems unfortunate that the experience of site managers is not used when choosing the type of rehabilitation. A more participatory, interactive and more educational two-way process would seem much more appropriate for this type of actors who are very important for the implementation of biodiversity protection policies and who see themselves more proactive than reactive.

How to cite: Pavlovic, V.: Are we neglecting local knowledge while choosing rehabilitation strategy for mining sites?, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-6613, https://doi.org/10.5194/egusphere-egu21-6613, 2021.

Progressive loss of productivity and plant diversity is a major in global rangelands. In African rangelands ecosystems, this process is partly attributed to heavy and uncontrolled grazing by livestock and wildlife, leading to land degradation. Therefore, restoring such degraded rangelands is critical for enhancing ecosystem health and securing the livelihoods of millions of people. Active restoration strategies, e.g. reseeding using indigenous perennial grasses has been identified as a viable ecological solution for restoring degraded African rangelands. Grass species indigenous to African rangelands Cenchrus ciliaris L. (African foxtail grass), Eragrostis superba Peyr. (Maasai love grass), Enteropogon macrostachyus (Hochst. Ex A. Rich.) Monro ex Benth. (Bush rye grass), Chloris roxburghiana Schult. (Horsetail grass) and Chloris gayana Kunth. cv Boma (Rhodes grass) were established in a semi-arid rangeland in Africa under natural conditions to compare their morphoecological characteristics and suitability for use in ecological restoration. Biomass dry matter yields, plant densities, basal cover, seed production, tiller densities and plant height were measured. Chloris gayana cv Boma and E. superba produced significantly higher dry matter biomass yields and seed production than other species. High biomass and seed production demonstrate their suitability to support livestock production and replenish depleted soil seed banks, respectively. Enteropogon macrostachyus and C. ciliaris displayed significantly higher values for plant densities, tiller densities and basal cover, also a component of establishment and ecological restoration success. Chloris roxburghiana ranked lowest in all the measured morphoecological characteristics. This may be a strong indicator of ecological site-specific characteristic of C. roxburghiana. Successful restoration of degraded African semi-arid rangelands using indigenous grass reseeding can best be achieved through careful selection of grasses to take advantage of their specific morphoecological characteristics. This selection should primarily be informed by the intended use of the rangeland.

How to cite: Mganga, K.: Morphoecological characteristics of grasses used to restore degraded semi-arid African rangelands, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9909, https://doi.org/10.5194/egusphere-egu21-9909, 2021.

Despite the efforts to reducing residues derived from thermal power stations, as near as 70% of fly-ash and other wastes end up in landfills. Definitive landfill covers are generally limiting for native plant establishment as these materials lack the characteristics of functional soils. This could compromise the success of restoration efforts increasing the risk of erosion. As part of a restoration project, we tested the efficacy of different erosion control covers to enhance soil functions, including C and nutrient cycling, water regulation, and erosion control. First, the fly-ash was encapsulated and covered with a one-meter of sandy-clay sediment mixed with 20 cm pine bark compost. Five native tree species were planted in four plots considering different soil cover treatments (Hydro-mulch, Coconut fiber mulch, Seeded mixed grasses, and no-cover). These were established considering a complete block design with nine replicates for cover treatment. To elucidate what soil function responded more rapidly to these treatments, we measured chemical soil indicators (C, N, and P total and available pools, pH, EC, CEC), microbial (Biomass and C, N, P pools), and physical (bulk density, texture, and infiltration). All these parameters were measured at three sampling intervals (0-20, 20-40, and 60-80 cm) immediately after the plantation and a year later (n=117 per year). Also, we installed triplicated erosion plots for each cover to quantify which cover was more effective in reducing erosion and runoff. Overall, total carbon and nitrogen content increases were found after the first year (p=0.04 and p<0.001 respectively) at 20 to 40 cm.

Similarly, available nutrients such as NO₃⁻, NH₄₊ showed a significant decrease in the first two depth intervals (p<0.001). Available phosphorus also showed a net decline in the first two depth intervals (p=0.02 and p<0.001). The no-cover treatment showed significantly higher amounts of water runoff and soil erosion (p=0.04) than the other three treatments. No differences were found in runoff and erosion between hydro-mulch, coconut fiber mulch, and grass cover. Our results show that soil's chemical properties (i.e., nutrient pools and nutrient availability) are sensitive to different cover types and respond rapidly after one year of plantation with native species. On the other hand, significant changes in physical properties are not visible yet. The experiment also concludes that all tested soil covers effectively reduced runoff and erosion compared to the control. These covers should be implemented in the initial stages of the revegetation.

How to cite: Crovo, O., Montecino, F., Alvarez, E., and Aburto, F.: Effectiveness of erosion control covers on soil quality recovery, runoff, and sediment production after forest restoration in a fly-ash landfill, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-13844, https://doi.org/10.5194/egusphere-egu21-13844, 2021.

Dryland areas are being seriously affected by degradation processes. The use of organic amendments in ecosystem restoration is an effective technique for accelerating soil regeneration processes in degraded drylands. The goal of this paper is to establish the effect of application of various organic amendments to degraded soil, on soil buffering capacity after 10 years. Buffering capacity is an important indicator, which is evidence of the overall condition of the soil ecosystem and influences a whole range of other soil properties, because buffering in soil is defined as the resistance of the soil to variations in pH. The experiment was carried out at the location called El Pinarillo in the Sierra de Tejeda, Almijara and Alhama Natural Park (southern Spain). The site is located at 470 m a.s.l., in the upper part of an alluvial fan (calcareous conglomerates). The experiment treatments were natural soil, bare soil, hydropolymers, pinus mulch, prescribed burnt, Sewage sludge. Application of hydrogel had the smallest effect on buffering capacity 10 years after application and manifested as just a slight decrease in soil buffering capacity while maintaining or improving other soil properties. The good buffering capacity of this variant also allows further work with the specific soil without greater risk of further degradation. Sludge was identified as the worst variant, whereas soil buffering capacity fell markedly, because sewage sludge may significantly inhibit microbial activity and decomposition of organic matter. This variant is not suitable for further use, because there is a risk of further soil degradation.

How to cite: Hueso González, P., Dvořáčková, H., Hladký, J., and Vlček, V.: Buffering Capacities in Mediterranean soils under different soil management, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9648, https://doi.org/10.5194/egusphere-egu21-9648, 2021.

Arsenic is a trace metalloid, potentially toxic for humans, animals and for plants. The problem of soil pollution with arsenic occurs in Poland only on a local scale, but in the Sudetes and in their foreland, there are several sites were arsenic was mined in the past. Particularly high concentrations of As in soils were confirmed in Złoty Stok, formerly the main European centre of arsenic industry. Decomposing forest litter as well as flooding can affect mobilization of As and other toxic elements, change their speciation in pore water and influence the toxicity to biota. This study examined the chemistry and ecotoxicity of pore water acquired from two soils that developed in a former As mining site: from the “Orchid dump” and from a nearby forest. Soils used in the experiment  contained very high concentrations of As: 2020 and 19600 mg/kg.  An unpolluted soil was used as a control. Soil samples were incubated in various moisture conditions (70%  of water holding capacity and 100% flooding), in the presence and absence of organic matter introduced with forest litter collected from a beech stand. Soil pore water was collected three times (after 7, 21 and 90 days) with MacroRhizon suction samplers. Chemical analysis of pore water involved the measurements of concentrations of As and potentially toxic metals, including Mn and Fe, as well as the concentrations of P. Ecotoxicity of pore water was examined in two bioassays: THAMNOTOXKIT F and RAPIDTOXKIT F. The Thamnocephalus platyurus toxicity test is a 24h bioassay based on the mortality of the test organisms (freshwater crustaceans). The sublethal effects were determined using RAPIDOTOXKIT, based on ISO standard 2011. This procedure measures the feeding inhibition of the juveniles of T. platyurus. A very high toxicity to T. platyurus was confirmed in the pore water of the soil richer in As, where all the organisms died. High mortality of crustaceans > 83,33 % was found in the pore water of soil collected from the Orchid dump, in particular after a longer incubation period. The addition of beech litter, as well as soil flooding, caused an increased mortality of test organisms that reached 100%, regardless of the time of incubation. In the pore water of less polluted soil, collected from the forest site in Złoty Stok, an increased mortality of crustaceans was observed upon the addition of beech litter. The RAPIDOTOXKIT test turned out less sensitive to high concentrations of As and other toxic components present in soil pore water. The feeding inhibition did not correspond directly with the concentrations of As. However, in the case of samples with the highest As concentration (130 mg/L), found in pore water of the Orchid dump soil treated with beech litter and fully flooded, the feeding inhibition reached 100%.

This research was funded by the National Science Centre of Poland; Project No. 2016/21/B/ST10/02221

How to cite: Szopka, K., Gruss, I., Gruszka, D., Karczewska, A., Dradrach, A., and Gałka, B.: The effects of organic matter and flooding on the ecotoxicity of pore water in soils developed in the sites of historical arsenic mining: application of biological tests with crustacean zooplankton, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-6573, https://doi.org/10.5194/egusphere-egu21-6573, 2021.

Self-overgrowing recovery of disturbed soils is one of important processes in reclamation of disturbed soils. Different types of anthropogenic disturbances followed by variety of soil types and their genesis leads to different bacterial communities, envolved in reclamation processes. Here we describe regional self-overgrowing soils in two location (Novgorod region, Northwest Russia). We analyse top level of industrial disturbed soils after coil mining (spoil tips with extremely low pH, and overburden soil) and sand quarry dumps followed by local undisturbed soils.

We perform 16s amplicone sequencind (v4-region) by Illumina MiSEQ and chemical routine analysis (pH, C, N and other). We provide alpha- and beta-diversity analysis, followed by CCA and analysis of differential abundance of taxa.

Sand quarry dumps and regional soils looks common on phyla level, and represent common soil phyla like Proteobacteria, Actinobacteria and Verrucomicrobia. Alpha-diversity metrics aslo are similar, despite difference in beta-diversity. Overburden soil and soil from spot tips, by contrast, is very different even in phylum level. Main intermediants here are Actinobacteria, Chloroflexi и Nitrospirae. Also they show extremely low alpha-diversity metrics.

This work was supported by RSF 17-16-01030, «Dynamics of soil biota in chronoseries of post-technogenic landscapes: analysis of soil-ecological efficiency of ecosystem restoration processes»

How to cite: Zverev, A., Kimeklis, A., Gladkov, G., Kichko, A., Andronov, E., and Abakumov, E.: Microbiological description of self-overgrowing spoil heaps and sand quarries in Nordwest Russia, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-2086, https://doi.org/10.5194/egusphere-egu21-2086, 2021.

Australia faced the most extreme and prolonged fire season in 2019-2020, resulting in tragic habitat loss for many threatened species and the destruction of many ecological communities.  Newnes Plateau Shrub Swamps are peatlands located in the upper Blue Mountains region of New South Wales, Australia. These ecosystems perform many important ecological functions while absorbing and filtering water and releasing it slowly back to the environment. Their functions are related to the control of peak flow events, water purification and the harboring of many threatened plant and animal species. Despite their ecological importance, the area has been intensively degraded through longwall mining processes, resulting in the lowering and loss of water tables in the area. In December 2019 these impacts were compounded by an intense prolonged drought period and extensive wildfire. While the effects of these combined factors on the vegetation have been analysed and revealed remarkable negative impacts in the swamps under mining pressures, the effects on the soil microbial communities and related soil functions have not yet been studied. To investigate both drivers (fire and mining activities), we selected three mined swamps and three unmined swamps to assess their soil microbial composition and diversity through Next Generation Sequencing, and to characterise the soil chemical composition. At each site, we collected samples considering three treatments, one in the swamp valley fill and two at two different heights of the swamp valley margin, focusing on the soil close to specific groups of plants (e.g. sedges and shrubs). For each site and treatment, three soil samples (~ 10 m from each other) of 10x10 cm and ~ 3 to 5 cm of depth were collected using a trowel. We aim to build 16S rRNA gene libraries and co-relate them with the soil chemical variables, to assess the impact on these microbial communities and their possible use as environmental indicators and basis for future applied initiatives in conservation and restoration.

How to cite: Machado de Lima, N., Thomsen, A., Ooi, M., and Muñoz-Rojas, M.: Bushfire impacts on a threatened swamp ecosystem: responses of the soil microbial communities and restoration, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-3778, https://doi.org/10.5194/egusphere-egu21-3778, 2021.

Arid and semi-arid (from hereafter dryland) ecosystems cover 70% of Australia, with climate change set to increase this area through desertification. Increased temperatures and reduced water availability are compounded through agricultural overgrazing. This degradation and habitat loss has led to biodiversity loss which disrupts the biogeochemical cycles that maintain these environments, creating a negative feedback loop, and making restoration efforts largely unsuccessful. With soil microbes being important drivers in dryland systems, understanding how different stressors impact the soil biome is needed to improve conservation and restoration efforts and promote resilience and resistance to climate change. Particularly lacking is understanding of these interactions over time.

Fowlers Gap Research Station is the only research station in the arid zone of Australia and was a working sheep station until 2019. Due to agricultural overgrazing the site is largely degraded however exclusion zones have been set up on the property ranging in time from 3 years to 40 years. These exclusion zones provide a powerful comparison for the impact of soil degradation on drylands. To investigate the impact of overgrazing on the soil biodiversity and ecosystem functions, we selected three of the exclusion zones paired with three degraded sites directly outside of the exclusion zone to assess their microbial composition and functional diversity, along with soil physicochemical properties. We aim to build 16S rRNA gene libraries and co-relate them with the soil chemical variables, to assess the impact of overgrazing on these microbial communities and the ecosystem functions they provide. This knowledge can be used to improve monitoring of conservation and restoration initiatives by providing environmental indicators for soil health over time.

How to cite: Stewart, J., Machado de Lima, N., Kingsford, R., and Muñoz-Rojas, M.: Soil microbial responses to passive restoration strategies in drylands: a temporal comparison of soil biodiversity and ecosystem function, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-16398, https://doi.org/10.5194/egusphere-egu21-16398, 2021.