Soil Disturbance Research Articles

Investigation on tillage resistance and soil disturbance in wet adhesive soil using discrete element method with three-layer soil-plough coupling model

To reveal the interaction between plough and wet adhesive soil, it's essential to establish an accurate coupling model of the soil-plough system. Traditional Edinburgh elasto-plastic adhesive contact model neglects the adhesion effect when two interactive particles are separated, leading to lower simulation accuracy. Here, an improved contact model of wet adhesive soil by introducing the adhesive force is proposed. Then a novel discrete element model of a three-layer soil-plough coupling system is established, where the liquid bridge force and the adhesion effect are considered. Furthermore, the corresponding soil bin tests are also conducted to demonstrate the effectiveness of the proposed model. Finally, the effect of soil adhesion, ploughing speeds and ploughing depths on the tillage resistance and soil disturbance is analyzed. Results show that the prediction accuracy of the proposed model increases by about 7%, moreover, the soil disturbed area decreases, while the tillage resistance increases with increasing soil adhesion.

Responses of Natural Microorganisms to Land Reclamation and Applications of Functional Microorganisms in Biorestoration of Coal Mining Area

Extensive coal mining causes significant ecological and environmental impacts on the local ecosystem, especially on the terrestrial ecosystem. Mining activities induce the degradation of topsoil physico–chemical characteristics and the succession of soil microbial communities. The soil microbial community is sensitive to soil disturbance and restoration practices, being significant in soil reconstruction and land restoration. Microbes could be effective instruments to restore or reclaim disturbed terrestrial ecosystems and indispensable, unambiguous, indicators to assess reclaimed soils. In the present review, we aimed to provide insight into the effects of mining and subsequent land reclamation on soil microorganisms and the importance and application of microorganisms in the reclamation process. We address changes in the diversity and structure of the soil microbial community after reclamation and discuss the main driving factors of the community. We hypothesize that there is a discernible pattern or regularity in the variation of microbial community composition during the process of restoration succession. By employing the life strategy concept, the study attempts to identify and understand how microbial communities evolve during land reclamation. Land reclamation could improve the nutrients in the soil while increasing the proportion of saprotrophic microorganisms. In community succession, vegetation, soil properties, and reclamation time are key determining factors. Whereas bacteria, fungi, and archaea showed different responses to these factors, as they responded differently to varied soil environments, nutrition, and plants, and occupied different biological niches. Finally, we describe the applications of microorganisms as land reclamation monitors or promoters. This knowledge and understanding can provide comprehensive insight into the soil health condition and strong support for forecasting and decision-making in mine land restoration.

Ecological Study of the Vegetation in the Loka Abaya National Park, Ethiopia

An ecological study of the vegetation in the Loka Abaya National Park, in the Central Rift Valley of Ethiopia, was conducted. Vegetation data and some environmental variables including physical and chemical properties of the soil, altitude, slope, and ecological disturbance were collected and subjected to the agglomerative hierarchical classification and ordination with the canonical correspondence analysis. For each of the community groups, the mean and standard errors were calculated from the environmental parameters to characterize the community types and quantitative relationships between environmental variables were analyzed by calculating Pearson’s product-moment correlation coefficient using the SAS computer software programme. A total of 198 plant species representing 79 families and 139 genera were collected and documented. Seven plant community types, namely, Vachellia brevispica Harms–Rhus natalensis Krauss, Ficus sur Forssk.–Vachellia albida (Del.) A. Chev., Panicum subalbidum Kunth–Cyperus latifolius Poir, Dodonaea angustifolia L. f.–Ximenia americana L., Combretum molle R.Br ex. G.Don–Combretum collinum Fresen., Ilex mitis (L.) Radlk–Olea europaea L. subsp. cuspidata, and Dichrostachys cinerea (L.) Wight & Arn, were identified. Ilex mitis–Olea europaea L. subsp. cuspidata community had the highest species richness, whereas the least species richness was recorded for the Panicum subalbidum–Cyperus latifolius community. The results of vegetation-environment relationships indicated that the measured environmental variables explained 74.99% of the total variation in floristic data. The results of the canonical correspondence analysis (CCA) of community-environment relationships indicated that among measured environmental variables, altitude (r2 0.0548, P<0.01), slope (r2 = 0.0241, P<0.01), pH (r2 = 0.01855, P<0.01), sodium (r2 = 0.01316, P<0.04), CEC (r2 = 0.01424, P<0.03), magnesium (r2 = 0.01282, P<0.04), potassium (r2 = 0.0152, P<0.02), and soil moisture content (SMC) (r2 = 0.01537, P<0.05) significantly explained the variation in species composition of the communities and their distribution. Therefore, ecosystem-oriented biodiversity conservation and restoration strategies will be implemented by considering these significant environmental variables.

Effect of Hand Frequency Weeding on Crop Growth Parameters and Yield

An effort made to reveal the literatures review about hand weeding frequency attributed on crop yield and crops growth parameters. This review paper has been literature reviewed necessary material that help assesses effect of hand hoeing on crop growth and weed management. Various weed controls methods practiced by small scale farmers of different agro ecology zones in order to compact the injurious effect of weeds on crop yields and growth parameters. Among available farmers practice I used for controlling weeds is hand-hoeing weed control system. Farmer practice of hand- weeding is very time consuming, physically demanding, and not cost efficient for a farmer especially where labour is scarce than other methods While, an advantage of manual control is that it minimizes soil disturbance, and decreases the likelihood of erosion and seed germination. A few farmers have started using herbicides to control weeds. However, herbicides have been found to be less effective than hand-weeding, as they require specific conditions which may be more limiting than other control method. This paper intended to reflect the current state to investigate the effect hand hoeing weeding frequencies on yield and growth parameters is still by far the most widely practiced cultural weed control technique in field crop production throughout the traditional agricultural sector, because of the prohibitive costs of herbicides and fear of toxic residue coupled with the lack of knowledge about their use.

Variations in the plasticity of functional traits indicate the differential impacts of abiotic and biotic factors on the structure and growth of trees in tropical dry forest fragments

Abiotic and biotic factors have considerable impact on the plasticity of plant functional traits, which influences forest structure and productivity; however, their inter-relationships have not been quantified for fragmented tropical dry forest (TDF) ecosystems. We asked the following questions: (1) what are the variations in the plasticity of functional traits due to soil moisture availability in TDF fragments? (2) what are the roles of soil nutrients and forest disturbances in influencing variations in the plasticity of functional traits in the TDF fragments? and (3) how do the variations in the plasticity of functional traits influence the structure and productivity of TDF fragments? Based on linear mixed-effects results, we observed significant variations among tree species for soil moisture content (SMC) under the canopy and selected functional traits across forest fragments. We categorized tree species across fragments by principal component analysis (PCA) and hierarchical clustering on principal components (HCPC) analyses into three functional types, viz., low wood density high deciduous (LWHD), high wood density medium deciduous (HWMD), and high wood density low deciduous (HWLD). Assemblage of functional traits suggested that the LWHD functional type exhibits a drought-avoiding strategy, whereas HWMD and HWLD adopt a drought-tolerant strategy. Our study showed that the variations in functional trait plasticity and the structural attributes of trees in the three functional types exhibit contrasting affinity with SMC, soil nutrients, and disturbances, although the LWHD functional type was comparatively more influenced by soil resources and disturbances compared to HWMD and HWLD along the declining SMC and edge distance gradients. Plasticity in functional traits for the LWHD functional type exhibited greater variations in traits associated with the conservation of water and resources, whereas for HWMD and HWLD, the traits exhibiting greater plasticity were linked with higher productivity and water transport. The cumulative influence of SMC, disturbances, and functional trait variations was also visible in the relative abundance of functional types in large and small sized fragments. Our analysis further revealed the critical differences in the responses of functional trait plasticity of the coexisting tree species in TDF, which suggests that important deciduous endemic species with drought-avoiding strategies might be prone to strategic exclusion under expected rises in anthropogenic disturbances, habitat fragmentation, and resource limitations.

Impacts of garlic mustard (Alliaria petiolata, Brassicaceae) invasion on oribatid mites in urban forest soils vary with the size of the invaded patch

Investment in non-native species management should be informed by knowledge of impact, including on native biodiversity and ecosystem function. Oribatid soil mites may be useful to evaluate the impacts of plant invasions since they are bioindicators of disturbance and soil ecosystem health. Still, more research is needed to characterize their responses to plant invasion, especially at the species level. Our objective was to determine the effect of invasion of urban forest understories by an allelopathic weed (garlic mustard, Alliaria petiolata (Brassicaceae)) on belowground oribatid mite species and communities. At two sites in central Alberta (Canada), over two years, we examined adult oribatid (≥ 300 µm) community assemblages, species richness, evenness, diversity, and abundance in plots invaded with garlic mustard and uninvaded plots with native vegetation. Environmental covariates known to be associated with soil invertebrate communities were also evaluated. Results suggest that the spatial extent of the garlic mustard invasion (patch area) mediates its impact on oribatid mite communities. However, there were no community-level impacts when considering invasion as binary (garlic mustard vs. native vegetation). Garlic mustard patch area influenced oribatid community composition and was positively related to species richness and several abundance metrics. The oribatid species we observed benefiting from garlic mustard invasion have been previously associated with disturbed soils. The mechanisms driving these patterns need more research, but we hypothesize they may relate to patch-specific resident times. Site was also a dominant factor influencing oribatid mite communities, and impacts of year, litter depth, and canopy cover were also detected at the species and/or community level. These findings contribute to our understanding of the impact of an invasive weed on bioindicating soil mite communities and species and highlight the importance of considering invasion context, including spatial extent when evaluating the impacts of invasive species on belowground invertebrate communities.

An Anthropogenic Soil Disturbance Map of Russia

An Anthropogenic Soil Disturbance Map of Russia

Development and Experimentation of Intra-Row Weeding Device for Organic Rice

Weeds in paddy fields can seriously reduce rice yield. An intra-row weeding device with double-layer elastic rods was designed, considering the differences in mechanical properties between rice and weeds, which can press weeds into the soil and avoid damaging rice. The elastic force of the elastic rods can be adjusted by changing the position of the regulating mechanism to adapt to different weeding conditions. A measurement experiment was conducted to determine the variation rule of elastic force. The quadratic orthogonal rotation combination discrete element simulation experiment, which used weeding depth and weeding speed as experimental factors, and the amount of soil disturbance and the force of the inner and outer elastic rod in the horizontal and vertical directions as experimental indicators, was conducted to study the interaction between the weeding device and the soil. The optimal weeding parameters were obtained: the weeding depth was 15 mm, the weeding speed was 0.9 m/s. The field experiment, which used the various parameters of the weeding device as experimental factors and the weeding rate and damaging seedling rate as experimental indicators, was conducted to determine the weeding effect. The experimental results showed that the optimal position of the regulating mechanism was 270 mm, with a weeding rate of 80.65% and a damaging seedling rate of 3.36%. The weeding rate can be increased by at least 11.18% by adjusting the regulating mechanism to a suitable position under the same weeding conditions. This study can provide a reference for research on weeding machinery for organic rice.

Influence of Planting Techniques and Integrated Nutrient Management on Soil Health in Rice (Oryza sativa L.)

The study investigated the impact of different planting techniques and nitrogen management at Sardar Vallabhbhai Patel University of Agriculture & Technology, Meerut (UP) during the rainy (kharif) season of 2019-20 on soil health in rice. Soil samples were collected at two depths, air-dried, and analyzed for aggregate size distribution using wet sieving. Particulate organic carbon (POC) was determined through aggregate slaking, while total organic carbon (TOC) content was assessed using rapid titration. Microbial biomass carbon (MBC) was calculated by incubating soil samples, followed by fumigation-extraction methods. Results revealed that soil pH and electrical conductivity remained unaffected by planting techniques and fertility levels. Aggregate size distribution analysis revealed that the Furrow Irrigated Raised Bed (FIRB) treatment promoted larger macro-aggregates (>2mm) at varying soil depths, while Conventional Tillage (CT) encouraged smaller micro-aggregates. Reduced Tillage (RT) combined with Farmyard Manure (FYM) and chemical fertilizer increased POC and TOC content, emphasizing the importance of reduced soil disturbance and organic matter addition. Conversely, CT exhibited lower POC and TOC levels due to intensive soil disturbance. RT with FYM and chemical fertilizer significantly enhanced soil MBC, highlighting their role in improving soil health and fertility.

Enhancing Afforestation Practices in Hilly Terrain: A Study on Soil Disturbance by Earth Augers Based on the Discrete Element Method

Afforestation operations in hilly regions are both arduous and unsafe. The mechanized afforestation method that takes into account soil and water conservation measures is deemed highly important. This paper examines the operational process and the auger’s mechanism of digging below the ground using the discrete element method (DEM). Using this model, soil disturbance parameters and reaction forces are satisfactorily predicted, exhibiting similar trends to experimental observations. This research also examines the influence of key parameters on soil disturbance and distribution patterns and analyzes the conditions and mechanisms of the formation of fish-scale pits to preserve soil and water. A field experiment of pit digging in woodland is carried out to test the performance of the device. The error rates for the actual and simulated values of the efficiency of conveying soil and the distance of throwing soil on plain terrain and slopes were 12.7% and 8.2%, and 8.6% and 15.7%, respectively. Overall, this research provides a theoretical basis for the innovative exploration, development, and optimized design of earth augers in hilly regions.

Evaluate the effectiveness of soil and water conservation interventions in the upper Awash Basin, Ethiopia

AbstractThe central highland of Ethiopia is facing significant challenges due to land degradation, which resulted in changes to the soil's physicochemical properties. This study aims to assess the effectiveness of different conservation methods in enhancing soil physicochemical properties, reducing soil loss and erosion, and maximizing land productivity in Ankober District of Kenseta watershed. For this study, two land uses (conserved and non‐conserved land), three slope positions, and three replication with the soil depth of 0–30 cm were used for undisturbed and disturbed soil samples data collection and analysis. The survey data were collected and evaluated from 106 randomly selecting respondents' households. The results showed significant variation in the mean value of soil physical properties (bulk density, soil moisture content, soil texture) within and between conserved and non‐conserved land. The chemical properties, including pH, EC, exK, CEC, OC, OM, and available P, also changed significant across land management types and along slope position (p < 0.05). Soil managed with stone face soil bund demonstrated significant improvement in soil physicochemical properties. The results were statistically significant difference at (p < 0.05) level of significance. Majority of the respondents' households explained the soil loss and rate of soil erosion were declined and land productivity status increased after the adoption of soil and water conservation practices in the study area. Therefore, proper conservation practices are vital in minimizing the rate of soil loss, ameliorating physical and chemical properties of the soils, and enhancing land productivity.

Nature's laws of declining soil productivity and Conservation Agriculture

Soils are critical for agriculture and natural ecosystems and need protection, and adherence to nature's principles. The objective of this work is to understand how nature manages resources and describe management of the 'living soil’ and its soil productivity and use nature's laws as guidelines for the management. These guidelines provide the foundation of modern Conservation Agriculture (CA) systems characterised by three principles: continuous no or minimum soil disturbance, permanent biomass soil cover, and biodiversity in crop rotations, all of which form the basis for the protection against degradation and for sustaining productivity. Historically, soil tillage was considered a necessary component of agriculture, but it is the root cause of soil degradation. Tillage-based agriculture with bare soils and poor cropping diversity violates nature's laws of soil productivity. Reasons for soil tillage are primarily for short-term convenience of farm management. The negative impacts of tillage on soil health and function may appear inconsequential. However, their cumulative effects over time result in major soil degradation and loss in productivity. Tillage in any form and intensity destroys soil biological, physical, chemical, and hydrological properties. Mechanical tillage is not experienced in natural ecosystems. In CA systems, natural conditions are emulated offering similar productivity, economic and environmental benefits to both large and small landowners globally. In 2018/19, CA was practiced on more than 205 million hectares across more than 100 countries. The impacts of climate change and tillage on food production and environmental degradation require the application of nature-based solutions as Conservation Agriculture.

The ability of soils to aggregate, more than the state of aggregation, promotes protected soil organic matter formation

Efforts to increase soil organic carbon (SOC) are pursued as a viable climate change mitigation strategy. Boosting SOC stocks requires increasing plant carbon (C) inputs and promoting their persistence in SOC. In well aerated mineral soils, water soluble inputs are expected to stabilize through chemical binding to minerals, forming mineral-associated organic carbon (MAOC) before or after microbial transformation, while structural inputs are expected to stabilize as particulate organic carbon (POC) via protection in soil aggregates. Although ample research is centered on the effects of soil aggregation, its disturbance (e.g., tillage), and microbial processing on SOC cycling, we still lack mechanistic understanding of how plant C input type (i.e., soluble versus structural) and disturbance (i.e., aggregate disruption) independently and in interaction affect POC and MAOC formation and stabilization in soils with inherently different degrees of aggregation.To this end, using 13C enriched structural and soluble plant inputs, we traced SOC formation and stabilization in a lab incubation experiment in soils with differing levels of aggregation, and capacity to form aggregates after disturbance. Our results showed that soluble plant inputs contributed substantially to MAOC and that higher formation and persistence of MAOC occurred in the highly aggregated soil. Moreover, the highly aggregated soil retained more soluble inputs stabilized as MAOC when disturbed. Disturbance in this fine textured, organic carbon rich soil stimulated regeneration of aggregates around structural plant inputs leading to greater persistence of aggregate-occluded POC. Soluble plant inputs, specifically, as well as structural plant inputs in the highly aggregated disturbed soil, compensated for SOC lost due to disturbance alone.Overall, this study provides mechanistic evidence suggesting that management strategies for SOC accrual should consider soil type, aggregation potential, and plant attributes to inform decisions surrounding tillage frequency and cropping regimes. Our mechanistic findings require testing. If confirmed in the field, they would suggest that no disturbance in tandem with high structural plant C inputs would benefit most SOC accrual in systems with soils that have little capacity to form organo-mineral complexes, including large aggregates. On the contrary, with sustained plant inputs, occasional disturbance in systems with soils that have a high capacity to form organo-mineral complexes can promote both POC and MAOC formation and stabilization.

Oil spill soil remediation using thermal desorption: Project synthesis and outcomes

AbstractFarmland within the Williston Basin of North Dakota was the site of the largest terrestrial oil spill to date in the United States in 2013. Over 3200 m3 of oil was released into the topsoil and subsoil, creating a risk to soil, water, and air resources. The purpose of this document is to provide a summary of results from a 7‐year project investigating the impacts of how thermal desorption (TD), the method used to remediate topsoil and subsoil, impacted contaminant reduction, soil function, and plant productivity simultaneously with site remediation. Soil disturbance and TD decreased soil organic matter and microbial communities, resulting in decreased soil function and plant production. However, TD did not reduce soil microbial recovery 4 years after treatment. Blending TD‐treated soil with uncontaminated topsoil appeared to minimize these negative effects and promote recovery of soil function. These findings provided critical information to stakeholders in the understanding of soil remediation and reclamation in this region.

Transfer seeds, hay, or soil blocks? The importance of the completeness of biological inputs to address dispersal and establishment limitations during the restoration of plant assemblages in floodplain grasslands

This study investigated different techniques of grassland restoration to overcome dispersal or establishment limitation, which are key processes influencing early‐successional plant community assembly. A fully randomized in situ experiment was set up in a former arable land in a floodplain along the Garonne river (south‐western France) to test for the effect of (1) the type and completeness of the biological input (any biological material—seed, hay, and soil—transferred to the site under restoration), (2) soil disturbance by deep tillage, and (3) their interaction on plant community dynamics for 5 years. All inputs influenced the plant community structure and composition. The effects depended on the type of the input but not necessarily in link with its completeness. High density and diversity seed mixture led to high levels of richness and relative abundance of target species like soil blocks, the input considered as the most complete. During the first year, hay transfer mostly influenced community assembly through negative litter effects. Delayed germination of several species contributed to buffer these early effects. This study supports the importance of dispersal limitation during early succession in degraded grassland ecosystems whereas soil disturbance had only subtle effects on the seed bank and standing plant community, indicating that competition and establishment limitation were of secondary importance in our study system. Our results suggest that even low‐frequency immigration events (e.g. when a few seeds are transferred within hay) can be of great importance providing that a sufficiently long time period is considered for grassland restoration.

Performance Evaluation of a Cicada-Inspired Subsoiling Tool Using DEM Simulations.

Subsoiling practice is an essential tillage practice in modern agriculture. Tillage forces and energy consumption during subsoiling are extremely high, which reduces the economic benefits of subsoiling technology. In this paper, a cicada-inspired biomimetic subsoiling tool (CIST) was designed to reduce the draught force during subsoiling. A soil-tool interaction model was developed using EDEM and validated using lab soil bin tests with sandy loam soil. The validated model was used to optimize the CIST and evaluate its performance by comparing it with a conventional chisel subsoiling tool (CCST) at various working depths (250-350 mm) and speeds (0.5-2.5 ms-1). Results showed that both simulated draught force and soil disturbance behaviors agreed well with those from lab soil bin tests, as indicated by relative errors of <6.1%. Compared with the CCST, the draught forces of the CIST can be reduced by 17.7% at various working depths and speeds; the design of the CIST obviously outperforms some previous biomimetic designs with largest draught force reduction of 7.29-12.8%. Soil surface flatness after subsoiling using the CIST was smoother at various depths than using the CCST. Soil loosening efficiencies of the CIST can be raised by 17.37% at various working speeds. Results from this study implied that the developed cicada-inspired subsoiling tool outperforms the conventional chisel subsoiling tool on aspects of soil disturbance behaviors, draught forces, and soil loosening efficiencies. This study can have implications for designing high-performance subsoiling tools with reduced draught forces and energy requirements, especially for the subsoiling tools working under sandy loam soil.

Ramp traps versus pitfall traps for collecting epigeal arthropods: a case study in a coniferous forest in Southwest Finland

ABSTRACT Pitfall traps are commonly used to sample epigeal arthropods, but they are not ideal in areas where soil disturbance is restricted or not possible. Ramp traps are a less well known alternative that does not require excavation. To compare the performance of the two trap types in capturing epigeal arthropods, both ramp (n = 12) and pitfall traps (n = 12) were set up in four paired transects in Korkiakallio forest (Turku, Finland), in summer 2022. The project team identified adult spiders to the species level, and other arthropods to the family level. Ramp traps captured significantly more individuals of ants (Hymenoptera: Formicidae), beetles (Coleoptera), true bugs (Hemiptera), and spiders of the species Minyriolus pusillus (Wider, 1834) (Araneae: Linyphiidae), while pitfall traps captured more myriapods (Myriapoda). Our findings provide additional evidence that ramp traps are not only a viable alternative to pitfall traps in challenging environments, but also complement (and should ideally be used alongside) pitfall traps.

Agroecological assessment of the efficiency of utilization of quail manure in the restoration of disturbed sod-podzolic soils with the formation of a stable herbage

The most acute environmental problems of our time include large volumes of bird droppings produced annually at large livestock complexes. At the same time, the sod-podzolic soils dominating in the Non-Chernozem zone of the European part of Russia are characterized by low reserves of humus, which quickly fall with intensive agricultural use and soil anthropogenic degradation. To restore degraded sod-podzolic soils, a peat-sand substrate enriched with compost from quail manure without and with the application of phosphogypsum to stabilize organic compounds of compost was used with the support of project No. 075-15-2021-1030 of the Ministry of Science and Higher Education of Russia. The vegetation experiment showed the maximum increase in plant biomass of the herbage in the variant with the combined use of compost and phosphogypsum: respectively, 30% higher than the control one. In the summer, there is an increased intensity of soil CO2 emissions in the variants with compost, but with a multiple more active increase in grass biomass growing, so one can talk about the atmosphere carbon sequestering nature of the technology of utilization of quail droppings during the restoration of disturbed sod-podzolic soils with the formation of a stable herbage.

Landscape-scale spatial variations of pre-Columbian anthropogenic disturbances at three ring ditch sites in French Guiana.

In the past two decades, repeated discoveries of numerous geometric earthworks in interfluvial regions of Amazonia have shed new light onto the territorial extent and the long-term impact of pre-Columbian populations on contemporary landscapes. In particular, the recent development of LiDAR imagery has accelerated the discovery of earthworks in densely forested hinterlands throughout the Amazon basin and the Guiana Shield. This study aimed to evaluate the extent and landscape-scale spatial variations of pre-Columbian disturbances at three ring ditch sites in the French Guiana hinterland. We carried out extensive soil surveys along approximately 1 km-long transects spanning from ring ditches through the surrounding landscapes, and drawn upon multiple indicators, including archaeological artifacts, macro- and micro-charcoals, soil colorimetry, and physicochemical properties to retrace the pre-Columbian history of these sites in terms of occupation periods, anthropogenic soil alteration, and ancient land use. Our results revealed a perennial occupation of these sites over long periods ranging from the 5th and 15th centuries CE, with local enrichments in chemical indicators (Corg, N, Mg, K, Ca) both within the enclosures of ring ditches and in the surrounding landscapes. Physicochemical properties variations were accompanied by variations in soil colorimetry, with darker soils within the enclosure of ring ditches in terra-firme areas. Interestingly however, soil properties did not meet all the characteristics of the so-called Amazonian Dark Earths, thus advocating a paradigm shift towards a better integration of Amazonian Brown Earths into the definition of anthropogenic soils in Amazonia. Soil disturbances were also associated to local enrichments in macro- and micro-charcoals that support in situ fire management that could be attributed to forest clearance and/or slash-and-burn cultivation. Taken together, our results support the idea that pre-Columbian societies made extensive use of their landscapes in the interfluvial regions of the French Guiana hinterlands.

ФЛОРА ГАЗОНОВ ДЕМСКОГО РАЙОНА ГОРОДА УФЫ

121 species belonging to 28 families were registered in the flora of the studied lawns of the Demsky district. The richness and systematic diversity of the species composition of the lawns of the Demsky district is associated with the presence of lawns of different ages, different stages of anthropogenic degression and different environmental conditions. The predominance of hemicryptophytes over other life forms of flora indicates the connection of lawns with the flora of natural meadow communities, and a large number of therophytes and hemiterophytes indicate prolonged and intense anthropogenic impact, soil disturbance, trampling and lack of care, this is confirmed by the high participation in lawn communities of species of a wide range of hemerobia and typical ruderals. The degradation of the lawn flora towards poly-metahemerobility will continue in the absence of measures for the reconstruction of lawns and constant care of the herbage.