首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
The objective of this paper is to assess the relationship between the cereals cultivated in the Late Bronze and Early Iron Ages (ca. 1250–400 BC) within the area of the present-day Czech Republic, and their environmental settings. The various charred caryopses of cereal species represented in the archaeobotanical assemblages from 35 archaeological sites differ, especially in the proportion of wheat and barley. The cereal assemblages were compared regarding site altitude, weather conditions, soils and soil productivity. The most important environmental variable influencing the choice of a particular crop seemed to be altitude which is correlated with other variables such as the length of growing season, mean annual temperature, soil quality etc. Although the ecological requirements of cereals cultivated in the Late Bronze and Early Iron Ages are not known, they presumably thrived under similar conditions to present-day species/varieties, and the strategy of past crop husbandry was based on similar principles as today, e.g. flexible adaptation to local environmental conditions, in an effort to achieve optimal yields and reduce the danger of crop failure.  相似文献   

2.
Abstract

A five year research project was set up to monitor soil moisture and groundwater levels of an extensive buried, mainly alluviated landscape located at the interface between the lower Great Ouse valley and the fen-edge in western Cambridgeshire. The intention was to monitor changes in hydrology, soil structure and geochemical status before, during and after large scale gravel extraction. The results presented here concern the pre-extraction monitoring period over three years. The project has identified three major landscape zones – shallowly buried former dryland, several sets of relict palaeochannel systems which still remain waterlogged, and a marginal zone between these where the monitored parameters fluctuate on a seasonal basis. The moisture levels of the alluvial overburden, buried soils and infills of the palaeochannel systems appear to act independently of each other, controlled by a combination of rainfall, agricultural land management, height above sea level and depth of burial. It is predicted that the removal of 1–3m of overburden accompanied by water abstraction when gravel extraction commences will lead to changes in the moisture regime of the immediate area and therefore of any contained archaeological contexts and the superficial sediments in this river valley/fen-edge landscape.  相似文献   

3.
An inadequate streamflow supply in Saginaw Bay, Michigan, affects the irrigation development in the region. Linear programming (LP) models are developed in this paper to help irrigation planners determine optimal irrigation scenarios. To incorporate the spatial variations of the soil and climate into the optimization models, soil associations are used as the basic analysis unit for estimating crop yields, irrigation requirements, and expected economic returns. The yields and irrigation requirements of corn, drybeans, and soybeans are simulated by the CERES-MAIZE, BEANGRO, and SOYGRO models at each of the twelve soil associations in the study area over the period of 1951–1980. The yield and irrigation requirement of sugarbeets are simulated by the YIELD model for all the soils in the study area over the period of 1956–1987. The crop prices, simulated crop yields and irrigation requirements, and variable costs are used to compute the expected gross margins and other coefficients in the LP models. The optimization results provide irrigation scenarios that are linked to specific soil associations, which are more useful to decision makers for identifying and targeting individual soils for irrigation development than are the spatially lumped optimal solutions. This study demonstrates that through integration of GIS and simulation models, spatial variations of the climate, soil, and water resources can be better represented in the optimization models to produce more realistic irrigation scenarios.  相似文献   

4.
Climate change and Zhou relocations in early Chinese history   总被引:2,自引:0,他引:2  
In Chinese history, the development of the Zhou tribes and the dynasties that succeeded them between 3550 and 2200 BP in the middle reaches of the Yellow River is known as the period of ‘Five Relocations’. Most of these relocations appear to have been forced by the pressure of nomadic invasions and occupations from the northern steppe. Historians simply attributed these relocations to political and military causes. However, palaeoclimatic studies show that the Zhou tribes and their successor dynasties developed at the demise of the Holocene Climatic Optimum when regional climate became highly variable and unstable. An integrated analysis of environmental change over the Loess Plateau and the Mongolian steppe facilitates a credible understanding of the linkage between climatic events and these relocations. It indicates that the relocations caused an expansion or contraction of the settled regions over the drought-prone semi-arid lands. During climatic amelioration, dry farming societies pushed upward to the Loess Plateau where increased precipitation and soil moisture allowed cereals to be cultivated. When hit by droughts and the associated disasters, both the dry farming societies and the nomadic tribes had to move southward to find an environment suitable for their food production. Migration and relocation were, therefore, basic strategies to secure the resources necessary to sustain an agricultural economy. The settled frontier was pulled back as dry farming societies from the upland plateau retreated to the lowland riverbanks of the Guanzhong Basin. Even though there were political and military intentions, climatic events played an essential role in the relocations of the Zhou tribes and the successive dynasties.  相似文献   

5.
The landscape of the 130 km2 Copper Basin, in the southeastern USA, became extremely degraded during more than a century of logging, mining, acidification, grazing, and fire. In the twentieth century, the Copper Basin became the focus of a series of reforestation programs and is now largely tree‐covered again. To investigate the effects of over 50 years of reforestation efforts, we developed a space‐for‐time substitution and conducted rainfall simulation experiments in ‘forest’ patches of various ages, at sites remaining unvegetated, and at forested reference sites outside the basin. At 59 sites, we monitored surface runoff and sediment detachment rates during 30‐minute rainfall simulation experiments; and at 54 of those sites, we determined soil organic matter content. Then, we measured litter and observed soils at 25 of the sites, and measured soil respiration at a site in each age zone. The results demonstrate that soil erosion by sediment detachment decreases within a decade following reforestation. Recently reforested sites have soils with significantly less organic matter and have higher runoff rates than forests more than 50 years old. The long‐term persistence of low infiltration rates suggests that, at sites where the A and B soil horizons and the biological health of the soil have been lost, restoration of the hydrologic function of a landscape by reforestation may require centuries.  相似文献   

6.
Sequences of buried soils of various ages in the sandy steppe of old river terraces of the Don River and several phases of soil deflation are related to both climatic factors (periods of desiccation or increased moisture caused by latitudinal shifts of storm tracks) and anthropogenic factors such as overgrazing. Climatic and anthropogenic factors are found to have reinforced each other in some periods, as in the 3rd and 16th centuries, and to have canceled each other out in other periods; for example, in times of increased moisture, when the eroded steppe sands again became overgrown with a plant cover despite continuing grazing of stock in the area.  相似文献   

7.
Several major cereal groups have been identified as staples used by the pre-urban, urban and post-urban phase populations of the Indus Civilisation (3200–1500 BCE): wheat, barley, a range of small hulled millets and also rice, though their proportional exploitation is variable across space and over time. Traditional quantification methods examine the frequency, intensity and proportionality of the use of these crops and help ascertain the ‘relative importance’ of these cereals for Indus populations. However, this notion of ‘importance’ is abstracted from the daily lives of the people using these crops and may be biased by the differential production (as well as archaeological survival) of individual cereals. This paper outlines an alternative approach to quantifying Indus cereals by investigating proportions of calories. Cereals are predominantly composed of carbohydrates and therefore provided much of the daily caloric intake among many late Holocene farming populations. The four major cereal groups cultivated by Indus farmers, however, vary greatly in terms of calories per grain, and this has an impact on their proportional input to past diets. This paper demonstrates that, when converted to proportions of calories, the perceived ‘importance’ of cereals from five Indus sites changes dramatically, reducing the role of the previously dominant small hulled millet species and elevating the role of Triticoid grains. Although other factors will also have affected how a farmer perceived the role and importance of a crop, including its ecological tolerances, investments required to grow it, and the crop’s role in the economy, this papers suggests that some consideration of what cereals meant in terms of daily lives is needed alongside the more abstracted quantification methods that have traditionally been applied.  相似文献   

8.
This study evaluated the soil properties of pre-Hispanic stone-walled terraces by comparing soil quality along terraced catenas in the Paca Valley, a tributary of the Mantaro Valley, Peru. Micromorphological and bulk analyses of terrace soils revealed that despite terracing soil horizonation largely followed the catena. Upland terraced fields had deeper A-horizons with higher biotic activity than uncultivated controls, but less fine material and greater carbonate accumulation. Midslope fields were highly variable in depth and soil properties reflecting considerable substrate and anthropogenic variations in this growing zone. Silts and clay accumulated in valley bottom terraces where pedofeatures indicate an ongoing downhill movement of fine material. The distribution of soil separates down Paca hillsides demonstrates that terraces help moderate, rather than control, the erosion of key soil fractions required for long-term agricultural productivity. This study illustrates how the loss of fine material is partly mitigated by soil consolidation in dense topsoil peds, microaggregates and saprolite. These aggregates are retained by terraces and contribute to deep soil profiles. Nevertheless, many fields show signs of degradation, especially from insufficient organic matter amendment. In addition to farming itself, buried soils and associated artefacts in valley bottom fields indicate mass soil movement, a likely result of disruption caused by Inca road and terrace construction. The poor soil quality of many upland terraces also confirms that stone-walled terraces were constructed on mediocre substrates for farming, indicating a high labour investment for marginal agricultural returns in these areas. Overall, Paca Valley terraces improve topsoil retention and promote deep soil profiles. However, these fields present quite varied growing substrates. It is also apparent that over the last millennium, soil depletion from cultivation has compromised soil quality through loss of fine material and organic matter. Shifts in farming practice away from pre-Hispanic practices such as long-fallow and middening appear to exacerbate this trend.  相似文献   

9.
Summary.   Archaeological research conducted in the La Mancha region (central area of the Iberian Peninsula) has made it possible to identify motillas . This specific type of archaeological site consists of a central fortification surrounded by an inhabited area. They appear in high densities throughout the plains of this area, distributed at regular intervals and located in places where the phreatic level is closest to the surface and the water has low salinity. The strong relationship between sites and water has subsequently been supported by fieldwork, especially in the Motilla del Azuer settlement, where a complex well that was cut into the natural terrace to reach the phreatic level has been documented. Research has also demonstrated that the large-scale storage of cereals was another significant function. The quantity and capacity of the different storage systems documented in two large enclosures suggest that these sites were engaged in the control and management of cereals.  相似文献   

10.
The South Downs in southern England have been farmed for 5000 years: the initial loess cover is now a thin, stony remnant as a result of erosion. During the 1980s, field monitoring of erosion events in an area of 36 km2 showed that average rates of erosion are low (0.5–5.0 m3 ha−1 yr−1), but that occasional storms result in losses of over 200 m3 ha−1 yr−1 on individual fields. On soils that are only 15 cm thick, such rates pose a threat to future farming. Almost all recent erosion has been on fields of winter cereals, which are bare in the wet autumn period. Of greater significance in the short term are the effects of soil-laden runoff (or muddy floods) on urban areas. Flood damage to property has been a regular event since the conversion of this area to winter cereals in the 1970s. Soil conservation measures have been negligible and flood protection has consisted mainly of engineering works and limited land-use change at sites where property damage has occurred. Conversion to grass under the Set Aside, and an Environmentally Sensitive Area (ESA) scheme, could be an effective soil conservation and flood protection approach. In the longer term, increasing stoniness of soils, the economic incentives for arable farming in marginal areas, and the success of legal proceedings relating to flood damage, will determine the future of erosion on the South Downs. Current farming systems clearly are unsustainable and would become more so under future climates without substantial site-targeted land use change.  相似文献   

11.
Abstract

Increasingly, developers and archaeologists search for ways to build on archaeological sites, while at the same time preserving the remains underneath. However, deciding which effects of construction on archaeological sites are acceptable and which are not is hampered by the lack of knowledge on the impacts of construction on archaeological sites. This paper provides an update on some of the effects of building on archaeological sites. Recent research had shown that displacement piles cause less disturbance in soft soils than previously thought. Moreover, replacement piles may be less benign that assumed up till now. Effects of loading on archaeological sites are described, and gaps in the knowledge on these effects are indicated. More research is needed in this field, especially on predicting soil disturbance and damage to weak materials. Impermeable surfaces and constructions on top of sites may affect the visibility of soil features due to decreased rainwater infiltration. Finally, a series of non-physical effects are mentioned that will have to be taken into account when deciding on allowing building on archaeological sites.  相似文献   

12.
For several decades, a growing number of protohistoric sites in Auvergne (Massif Central, France)—mostly excavated through preventive archaeology—have been subject to the collection of archaeobotanical analysis. This study presents the archaeobotanical results from ten La Tène sites dating from the last five centuries before the Roman conquest. In addition to providing an inventory of taxa, this paper concerns crops and crop cultivation methods. These results are interpreted in a wider context, dealing with crop husbandry, arable farming, storage and consumption practices. The sites are located in the Limagne plain within a 50-km radius around the city of Clermont-Ferrand. A total of 23,579 carpological remains were identified from 163 sediment samples totalizing a volume of 1096 l. Comparable to other sites in Gaul, the spectrum of cereals and pulses is restricted. Spelt (Triticum spelta), einkorn (Triticum monococcum) and foxtail millet (Setaria italica) are disappearing or becoming rare. A better control of agricultural techniques and increased yields is supposed during the ca. five centuries of the La Tène period. Mixed cultivation is hereby replaced by the sowing of monocrops. At the beginning of this period, farming systems are dominated by a polyculture of cereals and pulses. They become more specialized during the last two centuries before the Roman conquest; diversity of cereals and pulses is decreased.  相似文献   

13.
There is more woodland in Britain now than for many centuries and considering many international climate change mitigation policies, woodland cover, both in Britain and internationally, is being promoted. However, neither the management of existing woodlands nor their expansion should be at the expense of important archaeological evidence. Due to the large number of known archaeological sites, the large areas of land with uninvestigated archaeological potential and the expanding woodland cover, suitable mitigation strategies need to be developed to allow preservation in situ of important sites. An understanding of how woodland soils and the buried archaeological resource interact is, therefore, essential. This paper utilises ongoing environmental research into the mineral weathering rates in forest soils and considers its application to artefact preservation. The study concludes that soil water pH, its movement, and the saturation of dissolved ions in the soil solution are major factors determining both mineral and artefact longevity. A simple guide to artefact longevity based on these properties is proposed and a geochemical model for predicting loss is tested. These tools could be applied to any soil or individual horizon irrespective of land-use.  相似文献   

14.
潮湿环境土遗址的保护一直是非常困难的课题。当遗址与其他材质的文物共存时,保护难度更高。为了探讨遗址博物馆内病害发生的规律和影响因素,为未来潮湿环境土遗址保护措施的研究和设计提供依据,以杭州市萧山区跨湖桥遗址为例开展调查研究。发现盖棚可以防止雨水对土遗址的破坏,但造成了水和盐的单向迁移,是目前土遗址病害的主要根源。对于室内遗址博物馆,如何解决遗址土体水分单向迁移带来的破坏已经成为迫切需要开展研究的课题,建议尽快开展室内土遗址补水技术的实验研究。  相似文献   

15.
The object of this work was to relate the corrosion of tin-bronzes to the chemical condition of the soil in which they have been buried, most of them since the Bronze Age. Naturally, it was not easy to obtain recent hoards with their related soils, and considerable reliance had to be placed on recorded finds by taking recent soil samples from sites on which hoards were found over a hundred years earlier. Even so, with the exception of peat, a reasonable relationship appears to exist between the pH of the soil and the state of the metal. Acid soils are aggressive to metals and alkaline soils are benign. In no cases were sulphate reducing bacteria active in promoting corrosion. In the main, peat and peaty soils were benign in spite of their acidity, probably due to the protective action of polyphenols.  相似文献   

16.
Maize is the New World’s preeminent grain crop and it provided the economic basis for human culture in many regions within the Americas. To flourish, maize needs water, sunlight (heat), and nutrients (e.g., nitrogen). In this paper, climate and soil chemistry data are used to evaluate the potential for dryland (rain-on-field) agriculture in the semiarid southeastern Colorado Plateau and Rio Grande regions. Processes that impact maize agriculture such as nitrogen mineralization, infiltration of precipitation, bare soil evaporation, and transpiration are discussed and evaluated. Most of the study area, excepting high-elevation regions, receives sufficient solar radiation to grow maize. The salinities of subsurface soils in the central San Juan Basin are very high and their nitrogen concentrations are very low. In addition, soils of the central San Juan Basin are characterized by pH values that exceed 8.0, which limit the availability of both nitrogen and phosphorous. In general, the San Juan Basin, including Chaco Canyon, is the least promising part of the study area in terms of dryland farming. Calculations of field life, using values of organic nitrogen for the upper 50 cm of soil in the study area, indicate that most of the study area could not support a 10-bushel/acre crop of maize. The concepts, methods, and calculations used to quantify maize productivity in this study are applicable to maize cultivation in other environmental settings across the Americas.  相似文献   

17.
The open air Late Pleistocene campsite of Vale de Óbidos provided an opportunity to systematically assess the utility of electrical resistivity surveying for activity area detection at Palaeolithic sites. Detailed surface mapping facilitated the exploration of electrical resistivity effects caused by recent land use activities and post depositional processes. At Vale de Óbidos, tree throw events, ploughing, and earth moving have a more significant impact on soil resistivity than increases in soil moisture associated with pine tree stumps and roots. Resistivity results successfully discriminate activity areas containing hearth features and high densities of fire cracked rocks and artifacts. As an aid for understanding post-depositional processes at archaeological sites and to design excavation and recovery efforts, the technique has great potential for Palaeolithic archaeology and in other prehistoric contexts that lack major architectural remains.  相似文献   

18.
对裂隙进行充填灌浆,可以有效防止裂隙的进一步发展和雨水的渗漏,使遗址得以更好地保存。为比选出适宜于潮湿环境下窑址裂隙充填灌浆材料,采用烧料礓石、烧阿嘎土、砺灰三种传统石灰材料分别对浙江和福建四处"海上丝绸之路"遗址点的遗址土进行改性研究。测试改性后浆体材料不同龄期的抗压、抗折强度、收缩率,以及温湿度循环、冻融循环、水稳定性、安定性、耐碱性试验后试样的力学性能变化。试验结果表明,三种石灰类材料均具有良好的耐候性,但砺灰试样的耐冻融特性稍差、龄期强度低、收缩变形较大。烧料礓石改性试样具有较高的龄期强度、较低的收缩率、良好的耐候性。因此,建议将烧料礓石作为主剂应用于四处窑址的灌浆材料中。相关研究成果对窑址裂隙灌浆材料的选取具有实际指导意义。  相似文献   

19.
潮湿环境土遗址因含水率高、成分及所处环境复杂等特点,是文物保护工作中最难保护的文物之一,深入开展加固保护材料适用性及优化组合研究对于潮湿环境土遗址保护具有现实意义。以上海广富林文化遗址"F12房址"为对象,选取硅酸乙酯类加固材料Remmers SAE 300和SAE 300E,对其不同比例配合下的加固效果进行试验研究。通过表观形貌、渗透性、强度及抗水崩解性等指标分析,结果表明不同比例配合下的加固效果虽存在一定差异,但均能有效提高土体抗粉化能力和抑制霉菌生长,且当含水率较低时,加固作用将显著提高土体无侧向抗压强度和抗剪强度。研究结果对综合评定硅酸乙酯类加固材料在潮湿环境土遗址加固保护中的应用性有参考价值。  相似文献   

20.
A multi-proxy study was carried out to address climate–culture relationship from two trenches one each from Kaj and Kanjetar (mid-Saurashtra coast) deposited in a lacustrine setting, since ∼1960 Cal BC and ∼2230 Cal BC, respectively. The salinity of aqueous soil solution (0.1 ppt) and fresh water thecamoebians in both the sites indicate fresh water depositional environment. But, an increase in salinity (0.2 ppt) in the top clayey sediment in Kanjetar is attributed to water evaporation through upward capillary action from moisture deficit exposed land. The fragments of ancient potteries and other artefacts recovered from the bottom sediment provide evidences of Sorath-Harappan colonization in the vicinity which was not an urban site. The abundant cyanobacterium remains, low terrigenous organic matter, aquatic pollen and low thecamoebians in bottom sediment indicates low precipitation and arid climatic conditions ∼2000 BC. During this period the dominance of evergreen and moist deciduous arboreals from both the sites do not show equilibrium with the prevailing dry/arid climate and therefore, the pollen assemblage here represents the remnants of wetter middle Holocene vegetation in the region. Phytoliths of drought-tolerant summer season crops also reflects here changes made in the agricultural strategy by Harappans in response to climate. The increase in deciduous arboreal pollen since the last ∼2000 years represents equilibrium with the dry/arid climate. But, enhanced limnic conditions recorded with the help of thecamoebians during this period is attributed to changes in wetland configuration induced by hydrostatic changes in the river mouth that was largely defined by the dynamics of sediment deposition through rain-fed rivers/streams in the region.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号