Soil Biological Activity Research Articles

Different cropping systems impact soil health by improving soil biological activities and total organic carbon content

ABSTRACT This study assesses the impact of different cropping systems on changes in total organic carbon (TOC), its fractions and biological activities to evaluate the changes in soil health. The rice-wheat cropping system (RWCS) had significantly higher total organic carbon (TOC) (38.8%) and soil organic carbon (SOC, 43.6%) compared to the pearl millet-mustard cropping system (PMCS). Active C pools were significantly higher in soils under cotton-wheat (CW) and pearl millet-wheat cropping systems (PWCS) than RWCS, whereas passive C pools (63% of TOC), the microbial biomass carbon (MBC) and dehydrogenase activity (DHA) were highest under RWCS than other systems. Soils under these cropping systems exhibited a significant polynomial relationship of TOC with SOC and dissolved organic carbon (DOC). Two significant canonical discriminant functions involving TOC, SOC, DOC, very labile carbon (CVL), labile carbon (CL), less labile carbon (CLL), recalcitrant carbon (CR), MBC and DHA could distinguish the different cropping systems and contributed 94.7%. The principal component analysis identified that TOC, SOC, pH and EC were the most reliable and contributing variables for assessing soil health under different cropping systems. Three PCs explained the 79.2% variability of the total variance of the original data set.

Positive influence of apple trees on soil chemical and biological activities in agroecological garden orchard system

Positive influence of apple trees on soil chemical and biological activities in agroecological garden orchard system

Rice straw biochar and NPK minerals for sustainable crop production in arid soils: a case study on maize-wheat cropping system

Maize and wheat are the main cereals grown in Egypt. However, the country relies on grain imports to meet its local demands. In order to improve their production, appropriate fertilization programs are needed. The present study investigates the effects of amending a clayey soil of an arid region with rice straw biochar and NPK mineral fertilizers, individually or in combination, for increasing growth and productivity of maize and wheat crops. Additionally, impacts of these additives on soil biological activities and carbon (C) transformations in soil were a matter of concern herein. To achieve this objective, a field research of a randomized block design was conducted during the summer (maize) and winter (wheat) seasons of 2020/2021. The following treatments were considered: unmodified control (CK), 100% N inputs in the form of biochar (reference organic treatment, RSB) (T1), 100% mineral treatment (reference inorganic treatment, T2), 75% RSB + 25% NPK minerals (T3), 50% RSB + 50% NPK minerals (T4) and 25% RSB + 75% NPK minerals (T5). Additional doses of mineral fertilizers were added to treatments from T3 to T5 to maintain NPK inputs within the recommended doses. Key results showed that all additives significantly enhanced plant growth parameters and productivity. They also increased soil organic carbon level by the end of the growing season hence reduced soil bulk density, even for the treatment that received only mineral NPK applications (T2). All additives also upraised soil cation exchange capacity (CEC), soil available nitrogen (N), and soil salinity. However, sole application of biochar recorded the least increase in soil salinity. Combined mineral-organic treatments not only recorded the highest increases in soluble and microbial fractions of organic carbon and nitrogen in soil; but also noted the greatest improvements in growth and grain productivity of maize and wheat versus sole applications of mineral fertilizers or biochar. The alkaline nature of biochar was buffered by soil while no significant differences were observed in harvest index among treatments. In conclusion, combined use of biochar and mineral fertilizers, especially T5 is recommended for increasing soil fertility and wheat and maize grain productvity.

Plant probiotic microbes – trending microbes for plant growth and value addition of compost- a review

New agricultural approaches, including natural and organic farming, have developed organic and microbiological goods. Beneficial microbes known as plant probiotic microorganisms (PPM) are primarily found in soil and have coevolved with plants in a symbiotic or free-living relationship. By encouraging plant growth and health, these bacteria lessen the need for artificial fertilizers, support environmentally friendly agricultural practices, and improve plant health. Agroecosystem vigour, biodiversity, biological cycles, and soil biological activity are all enhanced by using plant probiotic bacteria in biologically based agriculture. By using beneficial bacteria to support the health and function of the host organism, plant probiotics aim to lessen the demand for toxic pesticides and fertilizers. Using these probiotic microorganisms will have a synergistic and advantageous effect on crop production. Plant probiotic microorganisms improve the overall quality of compost throughout the composting process by accelerating the breakdown of organic materials and introducing helpful bacteria. This rich compost adds beneficial bacteria to the soil, creating a healthy and productive environment. This review looks at the common plant probiotic bacteria, how they work, how they complement each other to improve compost quality and plant growth, how they might be used in agriculture, and how they could change how composting is done.

Differences in soil biological activity and soil organic matter status only in the topsoil of Ferralsols under five land uses (Allada, Benin)

Land use change on the Ferralsols of the Allada Plateau in southern Benin has led to a slight decline in soil organic carbon (SOC) stocks over the last two decades. However, as in many African landscapes, detailed characterisation and quantified data on the SOC stocks and soil biological activity under major land uses are still poorly understood. The aim of this study was to characterise the biological activity and organic matter status of Ferralsols (0–30 cm) under the five major land uses on the Allada Plateau, i.e., forests, tree plantations, young and adult palm groves, and croplands (pineapple, maize). Soil biological activity was assessed using the standardised litter decomposition method (Tea bag index) and soil respiration (during a 28-day soil incubation). Soil organic matter status was characterised by quantifying SOC pools: soil microbial biomass carbon (MB-C), potassium permanganate oxidisable carbon (POX-C), and SOC associated to soil particle-size fractions (e.g. particulate organic matter, POM, and SOC associated to the clay soil fraction). The results indicated that SOC pools and biological activity were lower in tree plantations than in forests. The standardised litter decomposition was also slower in tree plantations than in forest. In croplands and palm groves, SOC pools and soil microbial biomass and respiration were lower than in forests and tree plantations. This high level of biological activity in forests, and at a lesser level in tree plantations, was effective in accumulating carbon in C pools associated to the clay fraction. Agricultural land uses, such as croplands and palm groves decreased all the soil C pools even those associated to the clay fraction, except for POX-C. However, these land-use effects on SOC pools decreased strongly with depth. At 10–30 cm, the differences in SOC pools or soil respiration between the five land uses were no more noticeable. Our results indicated that the amount of organic inputs was an essential factor to sustain high soil biological activity and SOC stabilisation in the clay size fraction, but only in the topsoil. Maintaining forests in the landscape is a priority in order to preserve SOC stocks and soil biological activity, which neither monospecific tree plantations nor cultivation can do at the same level.

Effects of farmyard manure and chemical fertilizer application rates on soil biology, cotton and fiber yield

Organic and inorganic fertilizers have significant effect on plant physiology, yield per unit area, available plant nutrient contents and extracellular enzyme activities of soils. This study was carried out in field conditions in arid and semi-arid regions between 2020-2021 years, May 01. The effects of farmyard manure (FM) (20, 40, 60 Mg ha-1) and chemical (CF) (350 kg urea ha-1, 100, 200, 300 kg DAP ha-1) fertilizers applied at different rates on plant nutrient (N, P, K, Ca, Mg, Fe, Cu, Zn and Mn) contents, SPAD value and NDVI of cotton plants, seed cotton yield and soil enzymes (urease, catalase, dehydrogenase, alkaline phosphatase) were investigated. The results showed that FM applications significantly (p<0.01) increased the plant macro and micronutrients compared to CF applications, except for N (200 + 150 kg urea ha-1), Zn and Cu (300 kg DAP + 200 + 150 kg urea ha-1) in the 2021 cotton growing season. Mineralization of FM is slow under natural conditions; therefore, the use of FM alone is not sufficient to meet the nutrient needs of high yielding varieties. Urease and dehydrogenase activities increased significantly in FM treated soils compared to CF, while no significant (p<0.01) increase was recorded in alkaline phosphatase and catalase activities. Farmyard manure is a useful management practice for increasing soil biological activity. Physiological parameters of NDVI, SPAD and seed cotton yield significantly increased in FM treated soils compared to CF applications. The increase in cotton yield was 29.15%, in NDVI value was 22.38% and in SPAD value was 121.7%. The main issues with cotton in the area are the low organic carbon content of the soils, high clay content, arid and semi-arid soils, and their detrimental impact on the uptake of particular nutrients (N, P and B).

Эффективность поверхностного компостирования табачной пыли с использованием микробных смесей

Abstract. Tobacco dust is the main waste in the production of smoking products. The purpose is to study the possibility of tobacco dust utilization by surface composting together with microbial mixtures “Stimiks Kompost”, “Probioks Agro” and “Geostim”, directly in the field conditions, contributing to the restoration of soil fertility. Methods. In the years of research (2020–2021) tobacco dust was applied in doses of 5 and 8 t/ha in pure form and together with microbiological preparations. Scientific novelty. The method of using tobacco production waste as a fertilizer together with microbiological preparations is proposed. Results. It was established that for 30–60 days, tobacco dust application together with destructors, the content of basic nutrient elements in the soil increased: ammonium nitrogen form by 65–207 %, nitrate nitrogen by 83–225 %, available phosphorus by 21–107 %, exchangeable potassium by 80–194 %. Also Increasing of soil biological activity indicators was determined. The process of nitrifying ability of soil increases by 70–194 %, cellulose-destroying activity of microorganisms increases by 27–133 %, the amount of produced CO2 from soil increases by 61–129 %. The content of organic matter (humus) increases up to 4.2–5.5 % for the period of counting (4.0–4.7 % on the reference). Increase of moisture-holding capacity of soils in variants of experiment with tobacco dust and destructors was established (soil moisture for the period of research amounted to 18.4–25.5 %, in control – 17.1–18.7 %). The best results for surface composting of tobacco dust were obtained under wet conditions in 2021 (Hydrothermal coefficient (HTC) = 1.38), in 2020 HTC = 0.87. Mycological analysis revealed a decrease in soil infestation with pathogenic micro-mycetes in the variants of the experiment with tobacco waste. The increase in yield of bitter pepper (variety Baraniy rog) on the background of a mixture of tobacco dust and biodegraders amounted to 12–32 % (2020), seed cucumber (variety Dal’nevostochnyy 27) – 20–33 %.

Effects of long-term nighttime warming on extractable soil element composition in a Mediterranean shrubland

Understanding the soil biogeochemical responses to increasing global warming in the near future is essential for improving our capacity to mitigate the impacts of climate change on highly vulnerable Mediterranean ecosystems. Previous studies have primarily focused on the effects of warming on various biogeochemical processes. However, there is limited knowledge about how the changes in water availability associated to high temperatures can alter the bioavailability and dynamics of soil elements, thereby impacting ecosystem productivity, species composition, and pollution through soil biogeochemical and hydrological processes. In this study, we investigated the effects of long-term nighttime warming on the extractable concentrations of organic carbon (EOC), total nitrogen (ETN), total phosphorus (ETP), and 17 mineral elements (arsenic (As), calcium (Ca), cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), mercury (Hg), potassium (K), magnesium (Mg), manganese (Mn), molybdenum (Mo), nickel (Ni), lead (Pb), sulfur (S), strontium (Sr), vanadium (V), and zinc (Zn)) through environmental experiments in a semi-arid Mediterranean shrubland. We explored the potential biotic and abiotic mechanisms underlying the seasonal and long-term changes in extractable-mobilizable elemental composition and concentrations. Our findings revealed that prolonged warming led to higher mean annual soil temperature (with an average increase of 0.67 °C from 1999 to 2014), accumulation of soil organic matter (EOC) and extractable concentrations of soil elements (particularly increased ETP and extractable Ca, Mg, Cu, Sr, Mn, and As). These changes were attributed to uniformly higher activities of extracellular soil enzymes and/or lower plant photosynthetic and nutrient uptake capacity linked to more water deficit under warmer conditions. Seasonality unevenly altered element extractable concentrations, with soil microclimate (temperature and water content) and biological (soil microbial and plant) activity being the main drivers of this variability, thus influencing soil element composition. These results suggest significant fluctuations in the extractable concentrations of specific mineral elements in these soils, implying potential future variations in soil element composition as well as the loss of total element concentrations/contents in semi-arid Mediterranean ecosystems due to increasing warming. Therefore, these findings enhance our ability to predict ecosystem management strategies and mitigate the observed negative impacts on plant-soil systems and water quality in the context of climate change.

Crop Nutrition and Soil Fertility Management in Organic Potato Production Systems

Organic farming is a comprehensive production management system that fosters and improves the health of agroecosystems, encompassing biodiversity, biological cycles, and soil biological activity. The potato (Solanum tuberosum L.) is a crucial crop in organic farming systems, standing out as one of the most highly demanded organic products on the market. Among all crops, with potatoes, there is a very large yield gap between organic and conventional systems, attributable mainly to its intensive nutrient demands. The present review, considering the most relevant scientific literature worldwide, discusses the contemporary state of knowledge on crop nutrition and soil fertility management in organic potato crop production, analyzing the effects of animal manures, green manures, organic amendments, and biostimulants on organic potato tuber yield and quality. Overall, the main findings show a particular combination is needed to effectively maintain good soil fertility, satisfy the nutritional needs of the crop, and overcome the difference in potato yield between organic and conventional farming methods while meeting consumer demand. This combination entails using an animal manure or leguminous green manure with an organic soil amendment, and even better with a biofertilizer, such as a mycorrhizae-fungus-based one. It also emerged that more targeted studies are needed to select appropriate cultivars for organic potato farming systems to optimize this environmentally friendly production method.

Against wastelanding: distributed design at the pace of soil in the Conca de Barberà

This paper proposes a methodology for designers to work in the extensive yet marginal landscapes that are produced as part of the process of agricultural intensification. The distributed design approach, which focuses on enriching the existing bioinfrastructure of the soil, emerged out an ongoing research project in the Conca de Barberà, Spain. The project involves managing an interconnected series of currently unproductive on unmaintained fields through the rotational grazing of horses, with the hypothesis that the systematic grazing regime will catalyse soil biological activity. By attending to the soil infrastructure, the project necessarily developed a unique design approach. Management decisions became design problems and design work took on something of the call and response of management. Though it was shaped by the specific constraints and opportunities of the research project, the methodology is applicable to a wide variety of design projects in extensive landscapes with limited resources.

Vermicompost Effects on Soil Chemistry and Biology: Correlations with Basil's (Ocimum basilicum L.) Total Phenolic Content and Phenological Traits

This study explores the effects of vermicompost on the chemical and biological properties of soils, their nutrient content, and the impact on the growth and phenolic content of basil (Ocimum basilicum L.). Using a controlled experimental setup, we tested five dosages of vermicompost (0%, 4%, 12%, 20%, and 24%) to evaluate their influence on soil biological activity by measuring basal respiration (CO2-C), microbial biomass C (MBC-C), and dehydrogenase enzyme activity (DHA) as well as on basil's growth parameters and total phenolic content (TPC). The results show that vermicompost addition to soil enhanced soil microbial activity in direct proportion to the dose of vermicompost. The application of lower dosages of vermicompost (4% and 12%) significantly enhanced both fresh and dry weights, suggesting an improvement in nutrient uptake and soil structure, which likely facilitated better root growth and nutrient absorption. However, higher dosages (20% and 24%) were associated with reduced growth metrics, likely due to nutrient overload or salt stress. Notably, the highest vermicompost concentration (24%) led to a substantial increase in total phenolic content (TPC) in basil leaves, correlating with decreased growth metrics. This response indicates the plant's defensive mechanism against oxidative stress caused by excess nutrients or salinity from the vermicompost. A multiple regression analysis following a correlation analysis also revealed an inversely proportional relationship between phosphorus content in the soil and total phenolic content in basil leaves. Our findings illustrate that while moderate vermicompost dosages optimize plant growth and health, higher concentrations can strategically enhance phenolic content due to nutrient overload or salt-induced stress. These results offer critical insights for tailoring organic amendment applications to balance plant growth and biochemical properties in agricultural practices.

Impacts of Climate change on soil microbial diversity, distribution and abundance

Climate change, driven by anthropogenic activities, has far-reaching consequences for our planet. Among its many impacts, changes in temperature, elevated carbon dioxide levels, and shifts in greenhouse gas concentrations significantly affect soil ecosystems. In particular, soil microbial communities play a pivotal role in nutrient cycling, organic matter decomposition, and overall soil health. Soil microbial communities respond differently to the effects of climate change, like elevated warming and precipitation. The change in climatic conditions is reported to be adversely affecting soil biological activity directly through either drying or wetting of soil or affecting their associated plants. This review delves into the intricate relationship between climate change and soil microbial abundance, diversity, and distribution. The paper also discusses climatic change pressure on soil enzymatic activity and microbial biomasses, as well as soil faunal activity, as they are key indicators of soil health in a changing climate. Soil microbial communities cope with climate change by changing their diversity and physiological characteristics and by changing their symbiotic plants, which indicates the role of soil microbes in withstanding the negative impact of climate change.

Gas geothermometry, soil CO2 degassing, and heat release estimation to assess the geothermal potential of the Alpehue Hydrothermal Field (Sollipulli volcano, Southern Chile)

The Alpehue Hydrothermal Field (AHF) near the Sollipulli Volcano in the Southern Volcanic Zone of Chile shows promise as a significant geothermal resource. A comprehensive geothermal exploration survey was conducted, including the evaluation of hydrothermal gases, geothermometer calculations, and CO2 flux measurements, to assess the AHF's geothermal potential. Our results indicate that the hydrothermal gasses at the AHF primarily originate from primitive, mantle-derived sources, with some contribution from crustal sediments. Two different CO2 populations of fluxes were identified. One corresponds to the background emission related to the soil biological activity (mean ∼7.7 g·m−2·d−1), and the other, much more significant, emanates from an endogenous source related to the Alpehue hydrothermal reservoir (mean ∼461 g·m−2·d−1). Reservoir temperatures were calculated using gas geothermometry yielding average temperatures of 249 °C. The calculated heat flow rate of the AHF is approximately 3.3 MW and the heat flux corresponds to 156 thermal MW⋅km−2, which could be considered a medium geothermal potential comparable to other systems worldwide. Although further studies are needed to fully address its exploitability, this study presents favorable characteristics of the AHF that make it a promising avenue for further exploration.

Influence of Microalgae Biomasses Retrieved from Phycoremediation of Wastewaters on Yield of Lettuce, Soil Health, and Nitrogen Environmental Fate

The main purpose of this study was to investigate the effects of three microalgae strains, Chlorella vulgaris, Scenedesmus quadricauda, and Klebsormidium sp. K39, on the enhancement of lettuce yield and soil fertility and in mitigation of nitrogen losses in groundwater, focusing on some aspects of the complex soil-plant system. The experimental trials were carried in pots, and involved the application of microalgae cells at two different concentrations (50 and 500 mg kg− 1 of soil), alone or in combination with standard mineral fertilization. The yield, main morpho-biometric parameters, and protein content of lettuce seedlings, as well as the activities of key enzymes involved in the nitrogen pathway (nitrate reductase, glutamine synthase, and glutamate synthetase) at both root and shoot levels, were monitored and the results were compared to not-inoculated control plants. The nitrate leached due to over irrigation was also evaluated. Furthermore, even the effects of microalgae biostimulants on soil biochemical activity were analysed by monitoring fluorescein diacetate hydrolysis, dehydrogenase, acid and alkaline phosphomonoesterase, and urease activities. All treatments significantly improved lettuce growth, especially when combined with mineral fertilization, providing comparable levels to the control plants treated only with microalgae cells. Furthermore, microalgae treatments positively influenced soil biological activities, as evidenced by increased of the potential biochemical index of soil fertility (Mw). In conclusion, microalgae soil treatments may be considered as a viable strategy to assist growers in reducing the use of mineral fertilizers, with a view to improve plant growth as well as soil biological activity.

Effect of Mineral Fertilizers on the Biological Activity of Soils using Direct Seeding Technology

In the field, the effect of liquid mineral fertilizers and carbamide ammonium nitrate (LMF and CAN) in the agrocenoses of peas, chickpeas, coriander and flax on the biological activity of chernozems treated for a long time using null technology was studied. Among the biological parameters, the activity of enzymes involved in the carbon cycle (invertases, dehydrogenases), the intensity of soil respiration, the number of microorganisms, and the content of active carbon were evaluated. There is a difference in the effects of fertilizers on crops and different parameters of biological activity. The biological activity of the studied soils varied depending on the type of mineral fertilizer, as well as the cultivated crop.

Sustaining Soil Biological Activity: The Role of Extended Reduced and No-Tillage Techniques

Soil management techniques can have varying effects on various soil properties. This study investigated the impact of various tillage techniques on soil properties for 14 years. The experiment was conducted at the Çukurova University Research Station, located in a region with a dominant Mediterranean climate. The research aimed to assess the changes in soil organic matter (SOM) content, soil respiration (SR), dehydrogenase enzyme activity (DHA), and soil temperature (ST) under seven different long-term tillage practices. The results revealed significant increases (p ≤ 0.05) in SOM (17-115%), SR (19-37%), and DHA (63-142%), under conservation tillage compared to conventional tillage practices. Additionally, conventional tillage with stubble burned consistently had the lowest values across all measured properties. Seasons variations also significantly (p≤0.05) affected the observed values. These findings suggest that conventional tillage practices have a negative effect on the analyzed biological activities, with stubble burning further exacerbating this impact. Further research exploring the long-term effects of different tillage practices under varying crop rotations and soil conditions can contribute to the sustainable development of agricultural production in the region.

Exploring the potential of horse amendment for the remediation of HCHs-polluted soils

This study assessed for the first time the bioremediation potential of an organic horse amendment in soils contaminated with solid wastes of the obsolete pesticide lindane (α−hexachlorocyclohexane (α−HCH) = 80 mg kg−1, β−HCH = 40 mg kg−1, γ,δ,ε−HCH≈10 mg kg−1) searching for a self-sufficient bio-based economy. Four treatments were implemented: polluted (PS, ΣHCHs = 130 mg kg−1) and control (CS, ΣHCHs = 1.24 mg kg−1) soils and the respective amended soils (APS and ACS). A commercial amendment, coming from organic wastes, was used for soil biostimulation (5% dry weight), and the temporal evolution of the enzymatic activity (dehydrogenase, β-glucosidase activity, phenoloxidase, arylamidase, phosphatase, and urease) and HCHs concentration of the soils was evaluated over 55 days under controlled humidity and temperature conditions. The horse amendment positively influenced the physicochemical properties of the soil by reducing pH (from 8.3 to 8) and increasing the organic matter (TOC from 0.5 to 3.3%) and nutrient content (P and NH4+ from 24.1 to 13.7 to 142.1 and 41.2 mg kg−1, respectively). Consequently, there was a notable enhancement in the soil biological activity, specifically in the enzymatic activity of dehydrogenase, phenol-oxidase, phosphatase, and urease and, therefore, in HCH degradation, which increased from <1 to 75% after the incubation period. According to the chlorine position on the cyclohexane ring, the following ranking has been found for HCHs degradation: β-HCH (46%) < ε-HCH (57%) < α-HCH (91%) ≈ δ-HCH (91%) < γ-HCH (100%). Pentachlorocyclohexene (PCCH) and 1,2,4-trichlorobenzene (1,2,4-TCB) were identified as HCHs degradation metabolites and disappeared at the end of the incubation time. Although further research is required, these preliminary findings suggest that organic amendments represent a sustainable, harmless, and cost-effective biostimulation approach for remediating soils contaminated with recalcitrant HCHs, boosting the circular economy.

More efficient nitrogen utilization through wool pellet and soil inoculation

AbstractIn recent years, many alternative bio‐waste‐based fertilizers have been proven to have a beneficial effect on plant nutrition. These also include wool pellet, whose comprehensive evaluation of synergistic effects on plant development and soil biological activity is still a limited field of investigation. To address this, we explored the potential of combining soil inoculations and N‐rich wool pellet as ecologically sound alternatives to N fertilizers. In a pot experiment, we investigated the effect of Azotobacter vinelandii, the Trichoderma harzianum T34, and wool pellet, individually and in combination, on the growth and nitrate uptake of the test plants, as well as on the biological activity and permanganate‐oxidizable carbon of the sandy soil with low organic matter content. The combination of T. harzianum + wool pellet showed the highest biological activity and permanganate‐oxidizable carbon content, while the untreated control plants exhibited the lowest values. The treatment combination of wool pellet and A. vinelandii exhibited the highest nitrate uptake by plants. Measuring the concentration of photosynthetic pigments, net photosynthesis, transpiration rate, stomatal conductance, and total dry biomass, we found that the treatments led to a significant improvement in the photosynthetic intensity of lettuce plants. These results suggest that wool pellet served as a significant source of N and that their biological activity plays a key role in improving plant parameters. Moreover, the combination of microbial inoculants and wool pellet effectively increases N use efficiency in plant growth.

Effects of canopy gaps on microclimate, soil biological activity and their relationship in a European mixed floodplain forest

Forest canopy gaps can influence understorey microclimate and ecosystem functions such as decomposition. Gaps can arise from silviculture or tree mortality, increasingly influenced by climate change. However, to what degree canopy gaps affect the buffered microclimate in the understorey under macroclimatic changes is unclear. We, therefore, investigated the effect of forest gaps differing in structure and size (25 gaps: single tree gaps up to 0.67 ha cuttings) on microclimate and soil biological activity compared to closed forest in a European mixed floodplain forest. During the investigation period in the drought year 2022 between May and October, mean soil moisture and temperature as well as soil and air temperature fluctuations increased with increasing openness. In summer, the highest difference of monthly means between cuttings and closed forest in the topsoil was 3.98 ± 9.43 % volumetric moisture and 2.05 ± 0.89 °C temperature, and in the air at 30 cm height 0.61 ± 0.35 °C temperature. For buffering, both the over- and understorey tree layers appeared as relevant with a particularly strong influence of understorey density on soil temperature. Three experiments, investigating soil biological activity by quantifying decomposition rates of tea and wooden spatulas as well as mesofauna feeding activity with bait-lamina stripes, revealed no significant differences between gaps and closed forest. However, we found a positive significant effect of mean soil temperature on feeding activity throughout the season. Although soil moisture decreased during this period, it showed no counteracting effect on feeding activity. Generally, very few significant relationships were observed between microclimate and soil biological activity in single experiments. Despite the dry growing season, decomposition rates remained high, suggesting temperature had a stronger influence than soil moisture. We conclude that the microclimatic differences within the gap gradient of our experiment were not strong enough to affect soil biological activity considerably.

Assessment of the biological activity of soil in meadow plant communities comprising ash-leafd maple

Assessment of the biological activity of soil in meadow plant communities comprising ash-leafd maple