Types Of Terraces Research Articles

Terraces in species tree inference from gene trees

A terrace in a phylogenetic tree space is a region where all trees contain the same set of subtrees, due to certain patterns of missing data among the taxa sampled, resulting in an identical optimality score for a given data set. This was first investigated in the context of phylogenetic tree estimation from sequence alignments using maximum likelihood (ML) and maximum parsimony (MP). It was later extended to the species tree inference problem from a collection of gene trees, where a set of equally optimal species trees was referred to as a “pseudo” species tree terrace which does not consider the topological proximity of the trees in terms of the induced subtrees resulting from certain patterns of missing data. In this study, we mathematically characterize species tree terraces and investigate the mathematical properties and conditions that lead multiple species trees to induce/display an identical set of locus-specific subtrees owing to missing data. We report that species tree terraces are agnostic to gene tree heterogeneity. Therefore, we introduce and characterize a special type of gene tree topology-aware terrace which we call “peak terrace”. Moreover, we empirically investigated various challenges and opportunities related to species tree terraces through extensive empirical studies using simulated and real biological data. We demonstrate the prevalence of species tree terraces and the resulting ambiguity created for tree search algorithms. Remarkably, our findings indicate that the identification of terraces could potentially lead to advances that enhance the accuracy of summary methods and provide reasonably accurate branch support.

Agricultural terraces in Puebla, Mexico: An ethnopedological approach

Terrace systems have been instrumental in the evolution of agriculture across various cultural contexts. This technology offers several benefits, including soil and water conservation, improved soil fertility, enhanced agricultural management, and increased crop yields. Several studies have been conducted on agricultural terraces in Mesoamerica. Nevertheless, there has been a lack of research on anthropogenic soils and ethnopedological studies in Mexico. This study aimed to ascertain the local soil knowledge and describe the ancestral terrace systems within a popoloca community in southern Puebla, Mexico. An ethnopedological survey was conducted on a 10,366 ha area to determine the land types and terrace systems present. Surface terraced soil samples were collected, and nine soil profiles within runoff terraces were described. The objectives were as follows: 1) to characterize and describe terrace systems in Santiago Acatepec, 2) to understand the indigenous land classification system and 3) to study the relation and impact of terraces systems on soil formation and WRB classification. The results indicate two types of terraces (hillside and runoff terraces), covering 2578 ha of land. Farmers recognize eight distinct land classes, with unique characteristics and agricultural uses. The land classes encompass both anthropogenic and natural soils. These land classes are classified as Terric Anthrosols, Eutric Regosols, Eutric Leptosols, and Pellic Vertisols. These results show farmers' detailed knowledge about their soils and the advantages and limitations of terraces. The modern and ancient terraces were classified according to seven diverse types of embankments or walls. The traditional embankment, designated as “cuaxustles,” is associated with runoff terraces and is known to have a lifespan exceeding one hundred years. Following the construction of a terrace, the land in question can be cultivated for agricultural purposes after a period of two years. The traditional knowledge of the soil has enabled the farmers of Acatepec to establish new agricultural areas, select crops that are well-suited to the soil conditions and climate of the region, and implement long-term modifications to the landscape. The findings indicate that it is feasible to implement environmental modifications that prioritize soil conservation and enhancement on a significant scale while also considering economic factors and the time frame involved.

The role of topography feedbacks in enrichment of heavy metal elements in terrace type region

Minerals, metallurgy, and other production activities will cause a large number of heavy metal elements to leak into the natural environment. A large number of heavy metal elements have been found in the farmland soil, where the adsorption of plants enhances the enrichment. Here, we have selected a region with three terraces to conduct a whole-area soil sample collection and satellite hyperspectral data processing study to explore the role of terrain in this enrichment process. Five spectral transformation methods and four feature enhancement algorithms were designed, and the content extraction model was established to quantitatively retrieve eight heavy metal elements. The results indicates that the three terraces are the source state, transition state, and stable state of heavy metals respectively with the decrease of elevation; The correlation coefficient of various heavy metal elements exceeds 0.92, and the enrichment pattern is consistent although slope and aspect have no significant correlation with the enrichment of heavy metal elements; Local Cd exceeds 30.00%, Hg exceeds 10 times, and As exceeds 48.30% according to the indicator provisions of Chinese national standard (GB 15618-2018). Such knowledge extends our understanding of the abundance, migration, and enrichment of heavy metals from the perspective of topography, which is crucial for pollution assessment and soil remediation.

Rainfall–runoff process and sediment yield in response to different types of terraces and their characteristics: A case study of runoff plots in Zhangjiachong watershed, China

AbstractA field experiment was conducted in the Zhangjiachong watershed to analyze the characteristics of rainfall–runoff process and sediment yield under different types of terraces. Various runoff plots were utilized, and a two serial tank model was employed to simulate runoff generation and concentration processes, taking into account vegetation interception. A soil erosion model incorporating raindrop erosion and sheet erosion was established to replicate sediment yield and concentration process. The parameters of the rainfall–runoff model and soil erosion model were calibrated and validated using observed runoff and sediment yield data. The controlling factors on runoff and sediment yield were explored and compared. The results indicate that both calibration and validation outcomes were acceptable. The earth‐banked terraces–citrus demonstrated the largest coefficients of upper and lower surface runoff, while its upper runoff threshold of the upper tank and the runoff threshold of the lower tank were the lowest, suggesting that it was more likely to produce surface and subsurface runoff. On the other hand, the stone dike terraces–crops exhibited the smallest coefficients of upper and lower surface runoff, while its upper runoff threshold of the upper tank was the highest. The lower runoff threshold of the upper tank was the same across different types of terraces. Compared to the earth‐banked terraces, the stone dike terraces have a larger infiltration coefficient in the upper tank and a smaller infiltration coefficient in the lower tank. Sensitivity analysis indicates that the most sensitive factors affecting runoff simulation results are the runoff threshold and the infiltration coefficient of the lower tank. Terraces, whether constructed with earth banks or stone dikes, are effective in reducing soil erosion. However, during storm rainfall events, these terraces may be partially destroyed, resulting in a higher sediment yield than that of the same vegetation cover on slope land. Terraces with hedgerows have a more significant effect on reducing runoff and sediment than those without hedgerows.

Structural differences and exploration potential of basins in the eastern and western branches of the East African Rift System

The East African Rift System (EARS) is the youngest rift with the eastern and western branches, consisting of multiple secondary rifts. It is generally characterized by low extent of exploration and great exploration potential. Identifying the differences in hydrocarbon accumulation conditions in various rifts is very important in providing guidance for hydrocarbon exploration and selecting favorable exploration targets in this area. Based on the interpretation of first-hand seismic-geological data, and combining other materials such as commercial databases and open access literature, the structural characteristics of the main rifts in the eastern and western branches of the EARS are comparatively analyzed; based on the anatomy of the discovered hydrocarbon reservoirs, the rifts of the EARS are classified into four types depending on their structural styles, including double-fault type, simple single-fault type, single-fault transfer type, and single-fault terrace type, and the control of structural style over hydrocarbon accumulation in the EARS is discussed. In the Western Branch of the EARS, large rifts such as the Albertine Rift and the Tanganyika Rift are mainly of double-fault type and single-fault transfer type, and only some small rifts are of the simple single-fault type. The rifts in the Eastern Branch of the EARS are generally small; the rifts in the northern section of the Western Branch are mainly of the simple single-fault type, and those in the southern section are mainly of the single-fault terrace type. The hydrocarbon potential of double-fault rifts is the greatest, followed by that of simple single-fault rifts and single-fault transfer rifts, and the hydrocarbon potential of single-fault terrace rifts is relatively limited. The results obtained from a comparative analysis of the structures, sediment fills, and reservoir elements of various rifts show that the west side of the Albertine Rift, the southeast of the Tanganyika Rift, the Kerio Rift, and the land in the northwest of the Turkana Rift have great exploration potential.

Climatic and tectonic effects on the origin and evolution of the Dereiçi travertines (the Başkale Basin, Eastern Türkiye), and neotectonic implications

The Başkale Basin is located in the easternmost part of Türkiye, within a tectonically active area, and located at the intersection of Europe, Asia and the Middle East. In this study, the Dereiçi travertines, one of the most important products of neotectonism in the basin, were investigated sedimentologically, mineralogically and geochemically. To understand the neotectonic evolution of the travertine succession, the sequence was studied from bottom to top as regards morphology, lithofacies and U/Th dates. Crystalline crust, coated gas bubbles, shrub, paper-thin raft and palaeosol lithofacies have been detected in the Dereiçi travertines, which are morphologically of layer type, two ridge types and terrace type. The Dereiçi travertines commenced to precipitate at the intersection of the Işıklı and Ilıcak faults at 255.56 ±9.01 ka, and their deposition continues today. Travertine deposition paused twice between 198.31 ±18–143.07 ±1.5 ka and 96.73 ±8.34–61.59 ±5.4 ka, when palaeosol development took place. According to field and laboratory studies, the Dereiçi travertines developed under climate and tectonic control. The Işıklı and Ilıcak faults played active roles in the development of the travertines. As the travertine ages are linked to movement on both faults, the age of the Işıklı Fault should be 255.56 ±9.01 ka or earlier, and that of the Ilıcak Fault should be 143.07 ±1.5 ka or earlier.

Stone-walled terraces restoration: conserving biodiversity and promoting economic functions of farmlands in Lebanon

Dry stone-walled terraces are peculiar features of Mediterranean farmland, representing typical examples of social-ecological systems combining ecological functionality and ecosystem services provision. In the Shouf Biosphere Reserve (Lebanon) a program of restoration of abandoned terraces applying Forest Landscape Restoration (FLR) principles is ongoing from 2016, combined with biodiversity monitoring activities. This study illustrates preliminary results of the plant monitoring, with the aim to (1) draft a checklist of the plants found in the terraces, (2) compare plant diversity and evaluate consistency of species assemblages observed among 3 different terrace managements (abandoned, restored and intensively-cultivated) and (3) compare ecological and ecosystem service value of the plant communities in the 3 types of terraces. Overall, 332 species were observed, with significantly higher diversity found in abandoned and restored terraces compared to intensively farmed terraces. Similarly, species assemblages of restored terraces were closely related to abandoned and distantly related to intensively-managed terraces. According to the study, restored terraces provide the same ecological value and ecosystem services functions as abandoned terraces, significantly higher than intensively-managed terraces. This study showcases the effectiveness of FLR programmes in restoring economic and social functions of terraced Mediterranean farmland while maintaining ecological functionality.

ГЕОДИНАМІКА

The aim of the research presented in this article is to analyze the properties and geological informative value of the anisotropic transformations of gravitational and magnetic fields, which use averaging procedures, including analysis of Andreev-Klushin's method. Anisotropic transformations of potential fields are designed to detect and track elongated anomalies or their chains, caused by deep linear dislocations in the geological section. The study of the anisotropic transformations properties is based on the analysis of their depth characteristics, as well as theoretical and practical experiments. The study applies the analysis method of fault tectonics reflection features in anisotropic anomalies of gravimagnetic fields, in particular, on the example of the South-East of the Ukrainian Carpathians. It is based on the search of morphological signs of manifestation of deep faults and other long structural-tectonic dislocations in gravitational and magnetic anisotropic anomalies. The method also suggests tracing these elements, relying on the comparison of morphology, intensity, size and direction of anisotropic anomalies with published regional tectonic and geological maps. Results. The paper presents definitions and algorithms of such anisotropic transformations as Andreev-Klushin's methods of anticlinal and terrace types, anisotropic averaging and anisotropic difference averaging. The research allowed us to perform study of the geological informative value of anisotropic transformations of potential fields on theoretical and practical examples. It is shown that in the morphology of anisotropic gravitational and magnetic anomalous fields in the south-east of the Ukrainian Carpathians long local anomalies are traced. They are caused by fault tectonics, in particular deep longitudinal and transverse faults, as well as linear complications into sedimentary cover. The analysis of anisotropic anomalous fields reveals a number of characteristic features of large tectonic zones reflecting regional behavior of the foundation surface and deep faults; on its basis fault tectonics schemes of the South-Eastern region of the Ukrainian Carpathians can be constructed. The study traced a significant extension of the foundation of the Eastern European platform from the Maidan's ledge and the Pokutsko-Bukovynian Carpathians under the Folded Carpathians. The definition of a number of anisotropic transformations is given and their properties are considered. The work substantiated geological informative value of the anisotropic transformations morphology of potential fields in the study of the Ukrainian Carpathians and adjacent depressions fault tectonics. The use of anisotropic transformations of potential fields will increase the reliability and detail of tracing deep faults, as well as other linear dislocations both in the foundation and in the sedimentary cover. The study of fault tectonics is an important factor in the successful solution of problems in the search and exploration of areas which are promising for oil and gas deposits.

Effects of terracing on soil properties in three key mountainous regions of China

Terracing greatly affects soil properties, ecosystem services, human welfare and geographical sustainability. The purpose of this article is to determine the influence of terracing on soil properties across diverse regions in China. Three representative terrace types, including dryland loess terraces, dry-stone terraces, and paddy terraces, were selected as case study areas. Soil sampling was stratified according to thickness of soil layers in each terraced area. Based on field investigations and soil sampling, combined with the means of variance, correlation, redundancy and regression analysis, we analyzed the characteristics of soil properties in the terraces across three areas. Results showed that: (1) alterations of soil physicochemical properties mainly depend on differences between soil parent materials in such regions; (2) Due to the existence of “four-element isomorphism” in the ecosystem and reasonable human activities, paddy terraces had the greatest impact on soil properties which is mainly reflected in decreasing soil pH and increasing SOC, TN, and TK; (3) The content of SOC and TN in different areas was higher in terraced fields than in the sloped lands and decreased with soil deepening; (4) To maintain sufficient supply of soil nutrients and support the sustainability of agricultural terraces, it is necessary to apply manure to improve soil fertility and accelerate its aggregation in the terraces. For example, an increase in the application of nitrogen fertilizer in terraced fields in Hebei and Gansu provinces, which have a serious deficiency in soil available phosphorus (AP), is necessary to get greater amounts of P fertilization. The present study offers a theoretical foundation for the sustainability of terraced ecosystems through efficient crop production, which is the basis for strengthening the ecological security of terraced areas and promoting regional sustainability in those fragile mountains.

Classification of slope area types and hydrocarbon accumulation rules in Wuerxun-Beier Depression

After more than 50 years of exploration and development, Wuerxun-Beier depression has entered a high exploration stage. It is more and more difficult to find large-scale structural reservoirs. Therefore, structural-lithologic reservoirs in slope areas have gradually become the focus of exploration. Based on the overall study and dissection of the depression, the geological differentiation characteristics of the large-scale slope area are discussed. According to the occurrence of the slope, the intensity of tectonic activity, the intensity of source supply and the pattern of synsedimentary fault combination, the slope zone in the study area can be divided into six types, namely, the steep slope with strong source along the fault step type, the compound fault step type of medium slope with strong source, the reverse fault step type of the gentle slope with strong source, and the weak supply type. Different types of slope have different sand control mechanisms and reservoir forming characteristics, such as the source gentle slope forward fault terrace type, the weak source gentle slope reverse fault terrace type and the weak source middle slope forward fault terrace type. Source supply intensity and slope dip control the development type of sedimentary system, the combination of synsedimentary faults and valleys controls the distribution characteristics of sedimentary system. Through exploration practice, significant discoveries have been made on the southwestern, southeastern and northern slopes of Beixi, Wuerxun-Beier depression, which confirms that the slope area is the main breakthrough direction for oil and gas exploration and large-scale reservoir increase in continental fault-depression lake basins.

Potential geoheritage assessment; Dereiçi travertines, Başkale, Van (east anatolian Turkey)

Dereiçi travertines famous for their Pamukkale-like conveyors are located to the south of the Başkale district of Van. The travertines are located after the 30th km of Başkale - Hakkâri highway and after 12 km by the road separating to the west. In this study, the morphological analyzes of travertines bearing geological heritages and their evaluation as "geo-tourism" were investigated. The oldest travertines in the region are the Layer-Type Traverteners at the base. On the Layer Type Travertines are the shear cracks developed in the K 10 B and K 40 D directions due to regional compressions and the Ridge Type Travertines formed by the waters from this crack. Finally, the waters draining down the slope from the cracks opening in the northeastern slope of the Ridge Type Travertines form the old and current Terrace Type Travertines.There are also small-sized Cave Type Travertines in the void spaces of various sizes developed in back-type travertines. When considered in potential of geoheritage, the region draws attention with two Ridge Type Travertines, a traverten bridge, some non-active terraced travertine, and a waterfall along a shear crack.In addition, the appearance of the natural walls formed by the downwind water due to the inclination of the Ridge Type Travertines along the northeast patch is also worth seeing. Dereiçi Travertines is one of the most important regions to be evaluated and protected from the perspective of geoheritage. However, these geological assets have not been found to be interesting, but at the same time, they have recently become the targets of the managerships looking for marble industry. Moreover, because of the increasingly decreasing hydrothermal waters coming out of the cracks, some of these terraces are dried up and some of them are coming to the stage of drying.The measures to be taken in order to continue natural formation are discussed in this article.

Viability of a terrace covered with porous concrete paving blocks for coffee bean drying

The success of the coffee activity depends on the beans drying process since it influences the physical and chemical coffee quality, whose result can be good or bad quality beverages. In this sense, the type of terrace has considerable influence on the product’s final quality. Therefore, in this study, ground soil terraces and porous concrete paving blocks will be evaluated, and the experiment was conducted in the city of Cambuquira/MG. For this purpose, porous concrete and compressed earth blocks with dimensions of 50 cm x 50 cm x 10 cm were built, totaling 10 blocks of each type of terrace. The experimental design was in randomized blocks (RB), using cherry coffee, with 10 replications, with a total of 20 plots. For the evaluation of the water infiltration capacity in the porous concrete paving block, a cylinder of 30 cm in diameter was used placed in the center of the porous concrete block, and the lower edges rejoined with cement to guarantee the use of the internal area of the cylinder only. The drying process of coffee on a porous concrete paving block terrace provided better quality both in the beverage and in the reduction of the number of defects in the beans. In the city of Cambuquira, the potential for infiltration and storage of rainwater is 58.8 m³ year-1. Considering a 10-year lifespan, the construction of the porous concrete paving block terrace is economically viable concerning the ground soil terrace, providing gains of up to 15%.

Efficacy of orchard terrace measures to minimize water erosion caused by extreme rainfall in the hilly region of China: Long-term continuous in situ observations

Terracing and rainfall characteristics notably influence the water erosion processes. However, an extensive long term in situ quantitative evaluation of the approaches to control the water erosion in different orchard terraces has not yet been performed, especially considering the increasing frequency and severity of extreme rainfall events due to the global climate change. In this study, six types of orchard terraces, including slope land as the control (SLck), level terrace with bare (LTb) and vegetation taluses (LTv), outward (OTv) and inward terrace (ITv) with vegetation taluses and level terrace having front mounds and back ditches with vegetation taluses (MDLTv), were used to analyze the effects of extreme and ordinary rainfall events on the surface runoff and soil erosion. According to the measured data for twelve consecutive years, 356 natural rainfall events were divided into extreme and ordinary rainfall, based on the World Meteorological Organization standard. The results indicated that more severe surface runoff and sediment loss occurred under extreme rainfall: the runoff coefficient and soil loss under extreme rainfall were 2.6 and 11.5 times those under ordinary rainfall, respectively. The sediment yield (contribution rate, 42.9%) exhibited a higher sensitivity to extreme rainfall events compared to that of the surface runoff generation (contribution rate, 16.4%). Moreover, the reduction in the surface runoff and sediment in the extreme rainfall case differed for different orchard terraces. The average surface runoff coefficient and soil loss amount decreased in the following order: SLck>LTb>OTv>LTv>ITv>MDLTv. Nevertheless, the highest and lowest contributions of the extreme rainfall to the sediment yield occurred in the LTb (64.8%) and MDLTv (21.7%) plots, respectively. Therefore, severe talus erosion caused by extreme rainfall should be monitored, and a combination of vegetation taluses and front mounds and back ditches on the platforms is recommended as a sustainable strategy to prevent extreme water erosion when transforming slope land into orchard terraces.

Indigenous knowledge of terrace management for soil and water conservation in the Sikkim Himalaya, India

The main objective of this study was to understand the farmer’s indigenous knowledge of terrace management in the Sikkim Himalaya with reference to Rani Khola watershed. Primary data were collected through a mix of questionnaire surveys, focused group discussions, and field observations with a sample size of 300 households. Detailed documentation of the evolution of the terraces and their types, bunding material, types of risers, the relationship of slope and terraces dimensions, soil and water conservation (SWC) practices were performed. Remote sensing data was used to derive information pertaining to elevation, slope and land-use/cover of the watershed. The study reveals that dimensions and types of terraces are subjected to the elevation, slope gradient, local soil and vegetation cover. Leveled terraces were constructed on lower slopes while outward sloping terraces were more common on higher slopes. It was also observed that with the increase in slope angle, width and length of the terraces decreased. Terrace riser height was also correlated with slope; riser height unavoidably increased as slope increased. The study concludes that terraces in the study watershed are effective in reducing the slope gradient and length, and in turn helpful in trapping eroded soil, slowing soil movement and in due course reducing soil erosion and increasing agricultural productivity. It is suggested that for overall management of terraces, it needs to be combined with additional soil and water conservation practices.

Viñedos en terrazas en la región vitivinícola del Duero, Portugal: una perspectiva de la gestión del suelo y el agua

Los viñedos del Duero son un ejemplo sorprendente de protección del suelo, materializado, en un paisaje fuertemente humanizado, donde las terrazas cubren una gran parte de la región. Este trabajo tiene como objetivo presentar una perspectiva sobre las mejoras en la gestión del suelo y el agua en los viñedos en terrazas del Duero, como respuesta a las responsabilidades reales determinadas por el estatuto del Patrimonio Mundial de la UNESCO, para preservar un paisaje cultural, vivo y evolutivo. Después de enfatizar sobre la importancia de los viñedos en terrazas del Duero en el territorio continental portugués y las limitaciones naturales para la producción de cultivos que caracterizan el valle del Duero, se describen los tipos de terrazas presentes en el paisaje del Duero, junto con los cambios en el uso del suelo debido a las operaciones de las terrazas agrícolas. Además de la rehabilitación de las estructuras de piedra seca como parte de las intervenciones de preservación del patrimonio cultural de la región, las áreas de riesgo crítico en las laderas aterrazadas identificadas recientemente se identifican como una prioridad para las intervenciones de protección del suelo y gestión del agua. Se trata de las áreas de viñedos más expuestas al impacto directo de las lluvias erosivas y comprenden los pasillos entre líneas de la vid, especialmente en viñedos no aterrazados, los taludes desnudos de tierra en terrazas de origen reciente, y las redes de caminos y drenaje agrícolas, espacialmente coincidentes, en laderas empinadas plantadas extensivamente. Prácticas innovadoras de gestión del suelo y agua deben desarrollarse y probarse localmente en un diálogo cercano con los actores regionales.

The Model of Etch Rates of Crystallographic Planes of Sapphire Based on Step Flow Mechanism

In this paper, a model of etch rates of crystallographic planes of sapphire based on step flow mechanism is proposed, which explains the relationship between etch rates of and atomic structures of crystallographic planes accurately. By analyzing the atomic structure of sapphire, a method of identifying step-terrace structures of crystallographic planes is established. Step-terrace structures of crystallographic planes of sapphire can be composed of crystal units (cluster atoms) of terrace types, edge-terrace types and step types by different combinations. Etch rates of crystallographic planes of sapphire can be expressed as functions of removal rates of crystal units. Thus, the relationship between etch rates and atomic structures of crystallographic planes of sapphire is established. The values of removal rates of crystal units can be obtained by the established matrix equations of removal rates of crystal units and experimental etch rates of key crystallographic planes. Under the different experimental conditions, high coincidence between etch rates calculated by the model and experimental etch rates in the $ $ and $ $ crystallographic zones is achieved. It proves the validity of the proposed model. [2020-0089]

VIABILIDADE ECONÔMICA DO USO DE TRATOR/IMPLEMENTOS AGRÍCOLAS NA CONSTRUÇÃO DE TERRAÇOS

O objetivo deste trabalho foi analisar os custos operacionais do uso da mecanização agrícola na construção de terraços, bem como a viabilidade econômica da compra. O trabalho foi realizado no município de Montes Claros-MG. Os Custos Operacionais foram avaliados considerando a possível implantação de três terraços: Manghum, Nichols e Base Larga. Adotou-se um arado fixo de três discos para o tipo Manghum, um arado reversível de três discos para o tipo Nichols e um terraceador para o de Base larga. Mesmo com maior custo horário (R$ h-1), o terraceador proporcionou menor custo total (R$ terraço-1) e consequentemente maior número de terraços construídos por hora, devido à maior eficiência deste implemento. O Ponto de Nivelamento demonstrou que para o terraço tipo Manghum será viável adquirir o trator e arado fixo, se o número de horas trabalhadas superar 219,3 horas anuais, no terraço tipo Nichols será viável adquirir o trator e arado reversível com número de horas trabalhadas superior a 247,7 horas anuais e o terraço tipo Base Larga será viável adquirir o trator e terraceador, com número de horas superior a 167,8 horas anuais.

ПОТЕНЦІАЛ ТА ПЕРСПЕКТИВИ РОЗМІЩЕННЯ ЗАКЛАДІВ ДОШКІЛЬНОЇ ОСВІТИ НА ТЕРИТОРІЯХ ЗІ СКЛАДНИМ РЕЛЬЄФОМ У КОНТЕКСТІ ПІВДЕННОЇ УКРАЇНИ

ПОТЕНЦІАЛ ТА ПЕРСПЕКТИВИ РОЗМІЩЕННЯ ЗАКЛАДІВ ДОШКІЛЬНОЇ ОСВІТИ НА ТЕРИТОРІЯХ ЗІ СКЛАДНИМ РЕЛЬЄФОМ У КОНТЕКСТІ ПІВДЕННОЇ УКРАЇНИ

Effects of terracing on root distribution of Pinus tabulaeformis Carr. forest and soil properties in the Loess Plateau of China

Terracing is one of the most effective ecological engineering practices that improve soil anti-erosivity properties and support plant growth in the dryland loess hilly area and other similar regions. The objective of the study was to understand the vertical distribution of root in different terraces and their relationships with soil environmental factors in the Loess Plateau of China. The vertical root distribution in the 0–400 cm soil profile, fine root distribution and soil moisture, soil nutrients (soil organic carbon, total nitrogen, and total phosphorus) and soil anti-erosivity in 0–160 cm soil profiles (every 20 cm for one layer) were investigated using the ground-penetrating radar and soil coring methods in a Pinus tabulaeformis Carr. forest under three terrace types during the growing season of 2018. We highlight several key findings here. First, level benches had the highest root density (18.14 kg m−2), followed by fish-scale pits (13.95 kg m−2) and reverse-slope terraces (9.84 kg m−2), as well as the highest soil water content, nutrients and soil stability. Second, terracing caused significant differences in root distribution (P < 0.05), leading to the variation of soil moisture, nutrients, anti-erosivity (explained over 80% variation) and reduced spatial heterogeneities of soil water content and nutrients. Third, fine root density parameters attained the highest values in the topsoil (0–40 cm soil layer) and decreased with increasing soil depth in all the three terrace types (P < 0.05). Finally, fine roots contributed to soil water improvement, nutrient promotion and soil stabilization, while higher density of coarse roots might consume soil nutrients and reduce soil anti-erosivity. We thus suggest that level benches could be a more suitable terracing measure for plantation of P. tabulaeformis Carr., and to achieve soil melioration and fixation during the ecosystem restoration process in the Loess Plateau and other arid and semiarid regions.

Earthen Terrace Technologies and Environmental Adaptation in the Montane Forests of Pre-Columbian Northeastern Peru

ABSTRACTThe pre-Columbian Andes are renowned for agricultural terrace systems in areas of steep terrain. Most studies have concentrated on regions characterized by seasonally-variable limited precipitation, yet research in high-precipitation and cloud-forest regions of the North and Eastern Andes demonstrates the diversity of terrace technologies adapted to different landscapes. This paper presents research from survey, excavation, and digital modeling of three types of well-preserved agricultural terraces found in a 50 km2 area in central Chachapoyas, northeastern Peru. These terrace types—which we refer to as linear segmented, contour, and sinkhole—were all comprised entirely of earth, not stone. Results from digital modeling using ArcGIS hydrology tools indicate different manners through which each terrace type structured the movement of water over the ground surface, supporting previous arguments that similar earthen terrace infrastructure in Colombia, Ecuador, and eastern Peru were likewise designed to manage runoff drainage rather than support irrigation.