952 resultados para Degraded steppe
Resumo:
We report the results of stable carbon and nitrogen isotope analysis of 354 human and faunal samples from five archaeological cultures of the Minusinsk Basin, Southern Siberia – Afanasyevo, Okunevo, Andronovo, Karasuk and Tagar (ca. 2700–1 BC) – a key location in Eurasia due to its position on a northern corridor linking China and central Eurasia. The results indicate that the diet of Eneolithic to Middle Bronze Age (Afanasyevo to Andronovo) populations was primarily C3-based, with C4 plants only becoming an important component of the diet in the Late Bronze Age Karasuk and Early Iron Age Tagar cultures. Freshwater fish seems to have been an important constituent of the diets in all groups. The findings constitute the earliest concrete evidence for the substantial use of millet in the eastern Eurasian steppe. We propose that it was probably introduced from Northwestern China during the Karasuk culture at the start of the Late Bronze Age, ca. 1500 BC. We conclude with a discussion of the implications for the nature of pastoralist economies on the steppes.
Resumo:
There is a major problem with dating human skeletal material in Eurasian
steppe, possibly due to the freshwater reservoir effects (FRE). The goal of the
project is to examine the extent of the FRE in key areas of Siberia and
Kazakhstan through AMS 14C dating and stable isotope (δ13C, δ15N, δ34S)
analysis of c. 150 archaeological and modern samples. Here, we present the
very first results of the tests. We hope that within next years the study will
provide advanced knowledge of FRE across the region; improved 14C sampling
protocols for 14C and isotopic studies; new data on the chronology, diet and
isotopic ecology of particular archaeological sites, and a database on the
extent and variability of the FRE in the region
Resumo:
Freshwater reservoir effects (FRE) can cause a major problem with radiocarbon dating human skeletal material in the Eurasian steppe. We present the first results of research into the extent of the FRE in the sites of Borly 4 (Eneolithic), and Shauke 1 and 8b (Early Bronze Age), North-Eastern Kazakhstan. AMS 14C dating and stable isotope (δ13C, δ15N) analysis of associated groups of samples (32 samples, 11 groups in total) demonstrate that: a) the diet of the humans and fauna analysed was based on the C3 foodchain with no evidence of a C4 plant (such as millet) contribution; aquatic resources apparently were a continuous dietary feature for the humans; b) the first 14C dates obtained for the Upper and Middle Irtysh River region attribute the Eneolithic period of the area to the 34th-30th c. BC, and the Early Bronze Age – to the 25th-20th c. BC; there is a ca. 450 years hiatus between the two periods; c) the maximum fish-herbivore freshwater reservoir offset observed equals 301±47 14C yrs. As such, 14C dates from aquatic and human samples from the area need to be interpreted with caution as they are likely to be affected by the offset (i.e. appear older).
The paper also discusses the effect of a sodium hydroxide (NaOH) wash on δ13C, δ15N, C:Natomic levels and collagen yields of the bone samples. Our results indicate a minor but significant effect of NaOH treatment only on C:Natomic ratios of the samples.
Resumo:
Freshwater reservoir effects (FRE) can cause a major problem with radiocarbon dating human skeletal material in the Eurasian steppe. Recent research has demonstrated that, for the Eneolithic to Early Bronze Age sites of North-Eastern Kazakhstan, the maximum fish-herbivore freshwater reservoir offset observed equals 301±47 14C yrs, as such indicating that 14C dates from aquatic and human samples from the area apparently need to be interpreted with caution as they are likely to be affected by the offset. The current paper presents the new data on the FRE of the Eneolithic to the Early Iron Age sites of Kazakhstan and South of Siberia.
Resumo:
This paper examines the position of planning practices operated under precise guidelines for displaying modernity. Cultivating the spatial qualities of Cairo since the 1970s has unveiled centralised ideologies and systems of governance and economic incentives. I present a discussion of the wounds that result from the inadequate upgrading ventures in Cairo, which I argue, created scars as enduring evidence of unattainable planning methods and processes that undermined its locales. In this process, the paper focuses on the consequences of eviction rather than the planning methods in one of the city’s traditional districts. Empirical work is based on interdisciplinary research, public media reports and archival maps that document actions and procedures put in place to alter the visual, urban, and demographic characteristics of Cairo’s older neighbourhoods against a backdrop of decay to shift towards a global spectacular. The paper builds a conversation about the power and fate these spaces were subject to during hostile transformations that ended with their being disused. Their existence became associated with sores on the souls of its ex-inhabitants, as outward signs of inward scars showcasing a lack of equality and social justice in a context where it was much needed.
Resumo:
Grasslands in semi-arid regions, like Mongolian steppes, are facing desertification and degradation processes, due to climate change. Mongolia’s main economic activity consists on an extensive livestock production and, therefore, it is a concerning matter for the decision makers. Remote sensing and Geographic Information Systems provide the tools for advanced ecosystem management and have been widely used for monitoring and management of pasture resources. This study investigates which is the higher thematic detail that is possible to achieve through remote sensing, to map the steppe vegetation, using medium resolution earth observation imagery in three districts (soums) of Mongolia: Dzag, Buutsagaan and Khureemaral. After considering different thematic levels of detail for classifying the steppe vegetation, the existent pasture types within the steppe were chosen to be mapped. In order to investigate which combination of data sets yields the best results and which classification algorithm is more suitable for incorporating these data sets, a comparison between different classification methods were tested for the study area. Sixteen classifications were performed using different combinations of estimators, Landsat-8 (spectral bands and Landsat-8 NDVI-derived) and geophysical data (elevation, mean annual precipitation and mean annual temperature) using two classification algorithms, maximum likelihood and decision tree. Results showed that the best performing model was the one that incorporated Landsat-8 bands with mean annual precipitation and mean annual temperature (Model 13), using the decision tree. For maximum likelihood, the model that incorporated Landsat-8 bands with mean annual precipitation (Model 5) and the one that incorporated Landsat-8 bands with mean annual precipitation and mean annual temperature (Model 13), achieved the higher accuracies for this algorithm. The decision tree models consistently outperformed the maximum likelihood ones.
Resumo:
In this paper we search the concept of nonviolent resistance inquiring a rural experience from Rio Negro´s steppe. The initiative highlights the need to recognize the context of the resistance exercise and the consideration of three aspects: the evaluation and interpretation of space, the dispute to public policy and the restructuring of the family order. These three elements, which overlap material and symbolic aspects, are discussed from an organization of trade domestic craft production. The notion of “development” is discovered on the basis of the frameworks of values from which the reproduction of subordination is associated with this idea, and even the challenge of change is the basis of the proposal which reviews that development idea, and illuminates from this complexity the notion of “nonviolent resistance”.
Resumo:
The likely Reducing Emissions from Deforestation and Degradation (REDD+) mechanism includes strategies for the enhancement of forest carbon stocks. Recent concerns have been expressed that such enhancement, or restoration, of forest carbon could be counterproductive to biodiversity conservation, because forests are managed as “carbon farms” with the application of intensive silvicultural management that could homogenize diverse degraded rainforests. Restoration increases regeneration rates in degraded forest compared to naturally regenerating forest, and thus could yield significant financial returns for carbon sequestered. Here, we argue that such forest restoration projects are, in fact, likely to provide a number of benefits to biodiversity conservation including the retention of biodiversity, the prevention of forest conversion to agriculture, and employment opportunities for poor local communities. As with other forms of forest-based carbon offsets, there are possible moral hazard and leakage problems with restoration. However, due to the multiple benefits, we urge that enhancement of forest carbon stocks be detailed as a major component in the future negotiations of REDD+.
Resumo:
In the Western Australian wheatbelt, the restoration of native eucalypt forests for managing degraded agricultural landscapes is a critical part of managing dryland salinity and rebuilding biodiversity. Such reforestation will also sequester carbon. Whereas most investigative emphasis has been on carbon stored in biomass, the effects of reforestation on soil organic carbon (SOC) stores and fertility are not known. Two 26 year old reforestation experiments with four Eucalyptus species (E. cladocalyx var nana, E. occidentalis, E. sargentii and E. wandoo) were compared with agricultural sites (Field). SOC stores (to 0.3 m depth) ranged between 33 and 55 Mg ha−1, with no statistically significant differences between tree species and adjacent farmland. Farming comprised crop and pasture rotations. In contrast, the reforested plots contained additional carbon in the tree biomass (23–60 Mg ha−1) and litter (19–34 Mg ha−1), with the greatest litter accumulation associated with E. sargentii. Litter represented between 29 and 56% of the biomass carbon and the protection or utilization of this litter in fire-prone, semi-arid farmland will be an important component of carbon management. Exch-Na and Exch-Mg accumulated under E. sargentii and E. occidentalis at one site. The results raise questions about the conclusions of SOC sequestration studies following reforestation based on limited sampling and reiterate the importance of considering litter in reforestation carbon accounts.
Resumo:
Mining is an activity that tends to degrade the environment. The restoration of mining areas, aims to accelerate and improve the succession process according to its future use. The objective of this work was to rehabilitate a soil degraded by tin mining activities in the Amazon Basin (Jamari National Forest, State of Rondonia) with the application of water treatment sludge (WTS), and verify the effect of Sludge on Values of pH (CaCl2 0.01 mol L-1), organic matter, P, Ca, Mg, K, H+Al, and soil micronutrient contents when Cultivated with native plants, legumes, and grass species. A factorial (3 x 5) experimental design was used to optimize the rehabilitation of these areas including three N rates (100, 200, and 300 mg N ka(-1) soil supplied by WTS), five plant species (grasses, legumes, and native plants), and two controls (degraded soil with no fertilizer and degraded soil fertilized with mineral fertilizers), with four replications. WTS increased pH values. The chemical products used to treat the water contributed, in greater extension, to increase soil Ca and Fe contents. The use of WTS as fertilizer proved viable, since it contains nutrients for plants; however, nitrogen Should not be used as a criterion to define the rate of Sludge application, because it is present at small amounts in the WTS.
Resumo:
As part of a larger study evaluating several silvicultural techniques for restoring tropical moist forests on abandoned agricultural lands in southeastern Brazil, direct seeding with five early-successional Atlantic forest species was tested at three degraded sites, characterized by different soil types and land-use histories, within the Environmental Protection Area at Botucatu, SP. The species used in this study were Chorisia speciosa, Croton floribundus, Enterolobium contorstisiliquum, Mimosa scabrella, and Schizolobium parahyba. Scarified seeds of each of these species were sown in prepared seed spots in replicated, 0.25 ha mixed-species plots at an initial espacement of 1 m x 1 m at each site. of the five species planted, only two, Enterolobium and Schizolobium, showed good seed germination, seedling survival, and early growth rates, averaging 4.1-4.6 cm stem diameter and 1.5-1.7 m height growth during the first 2 years after sowing. These two species constituted 88-100% of the total stand density, which ranged from 1050 to 1790 stems ha(-1) at 2 years. Despite the poor performance of the other species tested, we observed that the natural regeneration of native forest species originating from remnant forests in the general vicinity of our study sites was significantly greater within the direct-seeded plots than in unplanted control plots that were protected from fire and other disturbances. Published by Elsevier B.V. B.V.
Resumo:
Speech signals degraded by additive noise can affects different applications in telecommunication. The noise may degrades the intelligibility of the speech signals and its waveforms as well. In some applications such as speech coding, both intelligibility and waveform quality are important but only intelligibility has been focused lastly. So, modern speech quality measurement techniques such as PESQ (Perceptual Evaluation of Speech Quality) have been used and classical distortion measurement techniques such as Cepstral Distance are becoming unused. In this paper it is shown that some classical distortion measures are still important in applications where speech corrupted by additive noise has to be evaluated.
Resumo:
As pastagens cultivadas do Cerrado brasileiro são responsáveis pela metade da produtividade da carne bovina destinada à alimentação da população, enquanto as culturas agrícolas o são pela terça parte de sua produtividade de grãos, desempenhando importante papel econômico-financeiro para o país. Dessa forma, no ano agrícola 2005/2006, na Fazenda de Ensino e Pesquisa da Faculdade de Engenharia de Ilha Solteira - FEIS/UNESP, foram estudadas a variabilidade e a dependência espacial entre atributos físicos do solo e a produtividade da soja, quando rotacionados após a pastagem degradada com Brachiaria, sobre um Latossolo Vermelho distroférrico. Também foram estudadas correlações lineares e espaciais entre esses atributos, apurando condições que proporcionassem aumento da produtividade agrícola. Para isso, na área com a referida pastagem instalou-se uma malha contendo 124 pontos amostrais, com espaçamentos de 10,0 x 10,0 e de 5,0 x 5,0 m entre eles, numa área total de 7.500 m². Dos pontos de vista linear e espacial, a elevada produtividade de grãos de soja pode ser explicada em razão do número de grãos por planta e da macroporosidade do solo. A alta variabilidade obtida na maioria dos atributos do solo denotou que a integração lavoura-pecuária é um sistema que proporciona heterogeneidade do ambiente físico do solo.