Lithological and Topographic Impact on Soil Nutrient Distributions in Tectonic Landscapes: Implications for Pleistocene Human-Landscape Interactions in the Southern Kenya Rift

Tectonically active regions are characterized by complex landscapes comprising soils with heterogeneous physicochemical properties. Spatial variability of nutrient sources enhances landscape biodiversity and creates heterogeneous habitats potentially attractive for animals and humans. In this study, we analyze the role of geological processes in the distributions of soil nutrients in the southern Kenya Rift, a key region in the interpretation of early human-landscape interactions. Our aim is to determine how spatial variations in rock chemistry, as well as topographic gradients and localized zones of rock fracturing from tectonic faulting determine the distributions of plant-available soil nutrients in soils. We hypothesize that present-day soil nutrient levels reflect the long-term chemical and geomorphological characteristics of the landscape and underlying parent material, and that regions with high nutrient availability occur along pathways correlating with locations of hominin fossil sites. Analyses of 91 topsoil samples from the main geological units show that Calcium (Ca) deficiencies predominately occur in shallow soils developed on trachytic volcanic rocks and granitic gneisses, while high Ca levels are associated with basaltic parent material and sedimentary deposits of mixed sources. XRF analysis of rock samples confirms that CaO levels in trachyte rocks are significantly lower than those in basalts, and Ca mobilization in basalt is more effective than in trachyte. Along two toposequences in densely faulted basaltic and trachytic rocks, we observed slope dependent soil nutritional gradients and a systematic increase of the concentrations of Ca, Mg and SOC in topsoils of colluvial sediments downslope of active normal faults. Known hominin sites in the region are located either along corridors of long-term Ca availability or at short-term nutrient hotspots potentially related to active CO2 degassing along active fault zones. This implies a strategic advantage of Ca-rich regions for hominin subsistence strategies, such as provision of predictable constraints on the distribution and mobility of grazing animals in complex tectonic landscapes. Our study implies that geological processes impact nutrient distributions in the southern Kenya Rift. Results of this study have further implications for understanding the role of soils in the interpretation of hominin-landscape interactions in the early stages of human evolution.

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Spatial Patterns and Drivers of Soil Chemical Properties in a Typical Hickory Plantation

10.21203/rs.3.rs-845777/v1 ◽

2021 ◽

Author(s):

Mengjiao Sun ◽

Enqing Hou ◽

Jiasen Wu ◽

Jianqin Huang ◽

Xingzhao Huang

Keyword(s):

Random Forest ◽

Soil Nutrients ◽

Spatial Patterns ◽

Abiotic Factors ◽

Soil Nutrient ◽

Parent Material ◽

Mean Annual Precipitation ◽

Nutrient Concentrations ◽

Available Phosphorus ◽

Mean Annual Temperature

Abstract Background: Soil nutrients play critical roles in regulating and improving the sustainable development of economic forests. Consequently, an elucidation of the spatial patterns and drivers of soil nutrients in these forests is fundamental to their management. For this study, we collected 314 composite soils at a 0-30 cm depth from a typical hickory plantation in Lin 'an, Zhejiang Province, China. We determined the concentrations of macronutrients (i.e., soil organic carbon, hydrolyzed nitrogen, available phosphorus, and available potassium) and micronutrients (i.e., iron, manganese, zinc, and copper.) of the soils. We employed random forest analysis to quantify the relative importance of soil-forming factors to predict the soil nutrient concentrations, which could then be extrapolated to the entire hickory region. Results: Random forest models explained 61%–88% of the variations in soil nutrient concentrations. The mean annual temperature and mean annual precipitation were the most important predictor of soil macronutrient and micronutrient concentrations. Moreover, parent material was another key predictor of soil available phosphorus and micronutrient concentrations. Mapping results demonstrated the importance of climate in controlling the spatial distribution of soil nutrient concentrations at finer scales, as well as the effect of parent material, topography, stand structure, and management measures of hickory plantations. Conclusions: Our study highlights the biotic factors, abiotic factors, and management factors control over soil macronutrient and micronutrient concentrations, which have significant implications for the sustainability of soil nutrients in forest plantations.

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Field-scale variability of soil test phosphorus and other nutrients in grasslands under long-term agricultural managements

Soil Research ◽

10.1071/sr13027 ◽

2013 ◽

Vol 51 (6) ◽

pp. 503 ◽

Cited By ~ 10

Author(s):

Weijun Fu ◽

Keli Zhao ◽

Peikun Jiang ◽

Zhengqian Ye ◽

Hubert Tunney ◽

...

Keyword(s):

Soil Nutrients ◽

Poultry Litter ◽

Soil Nutrient ◽

Statistical Correlation ◽

Soil Test ◽

Field Scale ◽

The North ◽

Positive Correlations ◽

Soil Test Phosphorus

Field-scale variation of soil nutrients in grassland is becoming important because of the use of soil-nutrient information as a basis for policies such as the recently introduced EU Nitrates Directive. This study investigates the field-scale variability of soil-test phosphorus (STP) and other nutrients in two grasslands with a long-term history of poultry litter application. Two fields (field 1 for silage and field 2 for grazing pasture) were selected, and soil samples were collected based on 12 m by 12 m (field 1) and 15 m by 15 m (field 2) grids. Data were analysed using conventional statistics, geostatistics, and a geographic information system (GIS). In field 1, STP values ranged from 12.4 to 90 mg L–1 (average 38.5 mg L–1). In field 2, STP values ranged from 4.3 to 130.0 mg L–1 (average 21.4 mg L–1). Attention should be paid to long-term poultry application, as the average STP values in both fields were much greater than the recommended agronomic optimum STP status in Ireland of 8 mg L–1. Coefficient of variation values of soil nutrients in field 2 were much higher than those in field 1. Log-transformation and Box–Cox transformation were applied to achieve normality. Statistically significant (P < 0.01), positive correlations between P and other nutrients were found in both fields. Exponential and spherical models were fitted to the experimental variograms of STP in fields 1 and 2, respectively. Compared with the counterparts in field 1, soil nutrients in field 2 had larger ‘nugget-to-sill’ values, revealing that sheep grazing could weaken the spatial auto-correlation of soil nutrients. A grid of 60 m by 60 m was recommended for soil sampling in grassland, based on this study. High STP concentrations in field 1 were in the north-eastern side, which was related to uneven poultry litter application. Strong spatial similarity of low STP, magnesium, and pH values in their spatial distribution were found in field 2, confirming their strong statistical correlation.

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The role of geology and climate in soil nutrient variability - potential drivers for large ungulate migrations in the Serengeti ecosystem (Northern Tanzania, East Africa)

10.5194/egusphere-egu2020-13969 ◽

2020 ◽

Author(s):

Eileen Eckmeier ◽

Simon Kübler ◽

Akida Meya ◽

Stephen Mathai Rucina

Keyword(s):

Volcanic Eruptions ◽

East African ◽

Near Surface ◽

Serengeti Ecosystem ◽

Geological Processes ◽

Basement Rocks ◽

Nutrient Variability ◽

Archean Basement

The East African Serengeti ecosystem hosts a great range of mammals and one of the world&#8217;s largest seasonal ungulate movements, with over 1.3 wildebeest and several hundreds of thousands of zebras and antelopes migrating through the region in a regular pattern. While climatic and biological drivers for this migration have been studied in great detail, the role of rock chemistry, weathering and resulting soil diversity as a source for nutrient provision has so far been largely neglected and needs detailed and systematic study.Geological processes provide important controls on long-term ecosystem dynamics. Volcanic eruptions, earthquakes, and rock weathering influence soil edaphic properties, which represent the ability of soils to provide vital plant-available nutrients, which therefore control grazing patterns of herbivores, particularly during birthing and lactating seasons. Studying the geological role in providing and distributing essential nutrients is critical to understand long-term drivers and stability of animal migrations in dynamic ecosystems. We have carried out a field reconnaissance study in the Serengeti National Park, with the aim to study variations in nutrient variability in soils and vegetation in relation to the chemical composition of soil parent material, i.e. volcanic or metamorphic rocks and sediments derived from those rock units, and under consideration of climatic variations.&#160;First results show that the Serengeti ecosystem can be subdivided into three geo-edaphic subregions that correlate with seasonal wildebeest grazing habitats.(1) The southeastern Serengeti (wet-season grazing), is characterized by soils developed on volcanic ash derived from recent eruptions of the Ol Doinjo Lengai carbonatite volcano. Here, we have identified deeper organic-rich soils with andic and vitric properties and varying amounts of carbonate concretions or near-surface calcrete horizons. High Na, K, and Ca levels of volcanic ashes suggest high levels of those elements in soils and vegetation in this region, also because the precipitation is lowest in this area.(2) In the central Serengeti (short-term transitional grazing), soils develop on Archean basement rocks including granitic gneisses, phyllites and banded iron formations. Geochemical signatures of these rock types suggest that soils in this region have lower levels in Ca, Mg, and plant available P, compared to the SE Serengeti, which is supported by the transitional nature of this grazing habitat.(3) Soils in the Northern Serengeti (dry-season grazing) develop on a diverse patchwork of Archean basement rocks as well as basaltic lavas and thick fluvial deposits. North of Mara river, the Insuria fault &#8211; a large normal fault of the East African Rift&#160; - creates a wide sedimentary basin dominated by soils developed on basaltic sediments. Here, higher precipitation leads to stronger weathering and leaching of nutrient elements.Our preliminary results suggests that geochemical variations together with continuous (syngenetic) pedogenesis through active volcanism or tectonic faulting and related fault scarp erosion created regions of high edaphic quality in the north and southeast of the Serengeti ecosystem, and that the patchy nature of soil edaphics is important to understand the underlying drivers of large scale migration of grazing animals in this region.&#160;

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Herbivores shape woody plant communities in the Kruger National Park: Lessons from three long-term exclosures

Koedoe ◽

10.4102/koedoe.v56i1.1165 ◽

2014 ◽

Vol 56 (1) ◽

Cited By ~ 27

Author(s):

Benjamin J. Wigley ◽

Herve Fritz ◽

Corli Coetsee ◽

William J. Bond

Keyword(s):

Soil Fertility ◽

Soil Nutrients ◽

Plant Communities ◽

National Park ◽

Woody Plant ◽

Kruger National Park ◽

Total Phenolic ◽

Population Structures

The role of grazers in determining vegetation community compositions and structuring plant communities is well recognised in grassy systems. The role of browsers in affecting savanna woody plant communities is less clear. We used three long-term exclosures in the Kruger National Park to determine the effect of browsers on species compositions and population structures of woody communities. Species assemblages, plant traits relating to browsing and soil nutrients were compared inside and outside of the exclosures. Our results showed that browsers directly impact plant species distributions, densities and population structures by actively selecting for species with traits which make them desirable to browsers. Species with high leaf nitrogen, low total phenolic content and low acid detergent lignin appeared to be favoured by herbivores and therefore tend to be rare outside of the exclosures. This study also suggested that browsers have important indirect effects on savanna functioning, as the reduction of woody cover can result in less litter of lower quality, which in turn can result in lower soil fertility. However, the magnitude of browser effects appeared to depend on inherent soil fertility and climate.Conservation implications: Browsers were shown to have significant impacts on plant communities. They have noticeable effects on local species diversity and population structure, as well as soil nutrients. These impacts are shown to be related to the underlying geology and climate. The effects of browsers on woody communities were shown to be greater in low rainfall, fertile areas compared to high rainfall, infertile soils.

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The long-term role of organic amendments in building soil nutrient fertility: a meta-analysis and review

Nutrient Cycling in Agroecosystems ◽

10.1007/s10705-017-9903-5 ◽

2018 ◽

Vol 111 (2-3) ◽

pp. 103-125 ◽

Cited By ~ 32

Author(s):

Yongshan Chen ◽

Marta Camps-Arbestain ◽

Qinhua Shen ◽

Balwant Singh ◽

Maria Luz Cayuela

Keyword(s):

Meta Analysis ◽

Organic Amendments ◽

Soil Nutrient

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The Effect of Ecological and Geographical Factors on Environmental Parameters as a Background for Vegetables Selection

Agricultural Engineering ◽

10.1515/agriceng-2018-0020 ◽

2018 ◽

Vol 22 (2) ◽

pp. 99-106

Author(s):

Uladzimir Skaryna ◽

Vitali Skaryna

Keyword(s):

Environmental Parameters ◽

Parent Material ◽

Ecological Sustainability ◽

Selection Efficiency ◽

Plant Selection ◽

Statistical Parameters ◽

Adaptive Ability ◽

Sustainable Productivity

AbstractThe aim of the study is to find out the role of the ecological and geographical fator in obtaining sustainable yields and the assessment of the environment as a background for the selection in breeding of vegetable adaptive ability. Objects of research: winter garlic, vegetables beans, headed salad. Research was conducted in various ecological and geographical zones of Belarus, Russia, Uzbekistan. Environmental parameters as the background for selection were determined using Kilchevsky’s, L. V. Hotyleva’s (1985), technique, Kilchevsky (1985). Differences between testing points on environmental parameters for determining the trait “yielding capacity” have been revealed, maximum environmental productivity at assessing various genotype sets has been determined. Long-term research showed that sustainable productivity depends on the ability of a genotype to respond to environmental conditions. Based on the obtained results, statistical parameters of quantity traits of the parent material, their variability depending on ecological-geographical factor and the character of influence on the potential yields and ecological sustainability have been received. Using various ecological and geographical zones helps to reveal the potential of plants in given conditions on sustainability and productivity parameters. Testing of winter garlic, beans, head salad allowed differentiation of them according to adaptability capacity at various set of genotypes. It was found out that research must be carried out at highly productive and analyzing backgrounds to get the required material. One of the main methods enabling to increase plant selection efficiency is the use of natural ecological backgrounds.

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