Actor and frontier types in the Brazilian Amazon: Assessing interactions and outcomes associated with frontier expansion

This paper analyzes frontier expansion in the Brazilian Amazon as a process that depends on multiple exogenous and endogenous factors operating at diverse scales, but whose trajectory depends on the dominant actor type (smallholders or medium- or large-scale landholders) occupying the frontier landscape. Despite the broad growing trend of pasture expansion for adoption of cattle ranching as the main land use associated with frontier expansion, some differences persist across actor types. In relative terms, medium- and large-scale landholders place most of their cleared forestland under pasture, and in absolute terms, largeholders have deforested more than smallholders because they hold larger tracts of land. Recently, however, deforestation activity has been increasing in frontiers occupied by smallholders who tend to convert a greater proportion of the forestland in their landholdings to agricultural land uses than larger-scale landholders, mainly to expand cattle ranching operations. Furthermore, smallholders tend to maintain higher cattle stocking rates than medium- and large-scale landholders, which tend to adopt extensive systems of cattle production. Both economic and human development indices in each frontier type vary according to actor type. While in absolute terms, higher per capita agricultural income levels are found in frontiers where largeholders predominate, the corresponding incomes are higher in smallholder frontiers when prorated by unit of land under crops and pasture. In addition, the Human Development Index is higher in frontiers with greater presence of large-scale landholdings.     

Projeto RADAM: a better look at the Brazilian tropics

Fifty-four % of Brazil's national territory, most of it in the Amazon, has been covered by Projeto RADAM. The original images are difficult to obtain and the examples used in this article were taken from secondary, but still adequate mosaics of the radar imagery. These illustrate the principal physical units of the Amazon, thevárzea, theterra firme, and several types of highland, as well as the principal kinds of rural settlement: native clearings, ranches and new colonies. Two illustrations are included from the extension of this imagery into northeastern Brazil, one showing the coastal mountain range and the other an oasis-like settlement in the semi-arid interior.     

Contesting Chinatown: Place-making and the Emergence of ‘Ethnoburbia’ in Brisbane,Australia

This paper juxtaposes the actual areas of settlement and settlement activities of Chinese migrants in Brisbane’s southern suburbs since the mid-1980s, with the concomitant, ‘government planned’ construction of the city’s Chinatown as an ‘exotic,’ ‘ethnic,’ and ‘cosmopolitan’ landmark. It argues that while the latter, as with Chinatowns in other Australian and world cities, has continued to appropriate the symbols of so-called ‘Chineseness’ to sell the locale to non-Chinese, the former, in recalling the notion of ‘ethnoburbia,’ significantly evinces actual Chinese migrants’ agency and role in place-making. In the process, these migrants have not only established a local, ethnically meaningful environment, but also challenged the still current metonymic Western image of the Chinese as preferring life in ‘ethnic’ urban enclaves that had its origin from early Chinese settlement and fundamentally detached from the lives of other ethnic groups per se. Indeed greater recognition and comprehension of such locales may go a long way to illustrate that many Chinese living in Australia today do not fit the territorial, place-based identity often associated with them in the imagination of mainstream society.     

Breaking the yield frontier of rice

Major increases in rice production have occurred during the last 25 years, due to large-scale adoption of high-yielding semidwarf rice varieties. However, the rate of increase of rice production has slowed down, and the rate of population growth of rice consumers is now higher than the rate of increase of rice production. Severe food shortages are therefore likely to occur in 20–30 years if the trend is not reversed. To meet these food needs, rice varieties with higher yield potential are needed. The yield potential of the modern high-yielding varieties grown under the best tropical conditions is 10 t ha^–1. A research program is under way to develop varieties with a yield potential of 15 t ha^–1. One strategy aims to develop new rice plants with a harvest index of 0.6 (60% grain: 40% straw by weight) and with an increased ability for photosynthesis to increase total biological yield. The harvest index of the modern high-yielding varieties is 0.5. Such new varieties should have a yield potential of 12.5–13 tons ha^–1. These new plant type varieties will be used to produce hybrid rices with a yield advantage of 25% over the best parent. Such hybrids would have a yield potential of 15 t ha^–1.     

Groundwater use by plants in a semi-arid coal-mining area at the Mu Us Desert frontier

The hydrogen isotope (deuterium- $ \delta D $ ) composition at natural abundance levels of xylem water, soil water, groundwater, river water, and rainwater was used to evaluate whether adult plant species use groundwater and to detect seasonal shifts (dry/wet season) in water sources for plants growing in a semi-arid coal-mining area (located at the frontier of the Mu Us Desert). A direct inference approach and the IsoSource mixing model were used to estimate the contributions of different sources to the plant xylem water. The results showed that (1) the $ \delta D $ values of rainfall fluctuated considerably, while those of groundwater were generally constant during the experimental period; (2) the $ \delta D $ patterns in plant xylem water suggest that groundwater was a significant source of water for transpiration in the dry season, while all five selected species reduced dependence on groundwater sources in the wet season; and (3) soil water from the deep layer (50–100 cm) was used largely by adult species possibly because of interspecific competition. These results indicated that coal mining would significantly affect plant growth by reducing the water supply if it leads to a water table decrease. Therefore, it is necessary to protect groundwater resources during the coal mining operations in the region.     

极端条件下的变质作用——变质地质学研究的前沿

在简单回顾变质地质学形成和发展的不同历程的基础上,扼要地总结了近年来有关极端条件下的超高压变质作用、超高温变质作用和很低温变质作用研究的现状和存在的问题。根据峰期变质温度的不同,结合其矿物组合和地质产状特征,进一步提出将超高压变质作用划分为低温超高压变质作用(峰期变质温度低于600℃)、中温超高压变质作用(峰期变质温度介于600~900℃)和高温超高压变质作用(峰期变质温度大于900℃)。低温超高压变质作用与大洋板块的冷俯冲作用有关,其研究对于探讨俯冲带水流体的循环和地幔水流体的成因具有重要意义;中、高温超高压变质作用与大陆深俯冲作用相关,是目前超高压变质作用研究的热点领域;高温超高压变质作用的研究与探讨地球内(深)部组成和结构相关,一直是地质学家关注的前沿问题。超高温变质作用研究正在向深入发展,中国有关超高温变质作用的研究才刚刚起步;很低温变质作用的研究长期以来没有得到应有的重视,随着研究手段和方法的不断完善和提高,将会有大的发展。极端条件下的变质作用是近年来固体地球科学研究取得的重要进展,是目前变质地质学研究的前沿领域。     

Cracking the nut of agribusiness and global food insecurity: In search of a critical agenda of research

The article examines some of the main trends of the modernisation of agribusiness and raises some questions about geographical transformations taking place in the centre and north of Brazil. The country represents an emblematic case of neo-liberalised agriculture in need of further investigation. It is discussed in the text how corporate, industrial-scale agribusiness practices in Brazil bring back some spectral elements of capitalism, which never disappeared and in which the invisible becomes visible again. It is a phenomenon of multiple dialectics that needs further theoretical, methodological and investigative elaboration. The most dramatic circumstances, and most interesting for academics to study, are at the frontier of the expansion of agribusiness, where spatially and temporally patterns are heterogeneous and largely unpredictable. Agribusiness is especially promoted at the agriculture frontier in Brazil because it is in itself an economic, ecological and ethical frontier. Therefore, critical research into the complexity of contemporary agribusiness should really be about the political economy of alternatives to the highly vulnerable and unsatisfactory approaches to food and agriculture that prevail today and continue to expand unabated.     

A geophysical view of the Southeastern Brazilian margin at Santos Basin: Insights into rifting evolution

This study investigates the rifting structures of Santos Basin at the Southeastern Brazilian margin, based on an integrated geophysical approach. Our aim is to constrain the crustal basement topography of central and northern Santos basin, the presence of magmatism and the role of inherited structures in space and time through the rifting processes. We present a new high resolution aeromagnetic dataset, which in correlation with gravity anomalies enables us to interpret the tectonic trends and crustal basement structures. We calculated the magnetic basement depth for the central and northern Santos Basin using power spectrum analysis. The obtained depths range between 2 and 9 kms, and are comparable with results from previous works. From our integrated study, three margin domains could be identified, which display distinct rifting structures and are characterized by important lateral variation along the margin. The proximal domain displays trends and magnetic basement blocks NE–SW oriented, i.e., parallel to inherited onshore crustal basement with an inflexion to E–W oriented trends; the necking domain is characterized by oblique magnetic basement highs and lows (E–W and NW–SE) and a structural trend change. The trends and magnetic basement highs are bounded by NW–SE negative anomalies, interpreted as transfer zones. Oceanwards at the distal domain, the lineaments and transfer zones show a progressive structural inflexion to ENE and E–W, sub-parallel to adjacent South Atlantic Fracture Zones. The observed crustal basement architecture and segmentation suggest the reactivation of pre-rift structures at the proximal margin and the obliquity of rifting relative to them. From the proximal domain oceanwards the structural pattern may reflect the passage from a “continental type” domain, where lithospheric inheritance controls the deformation, to a distal margin where this influence diminishes and “new” structural trends are formed. We propose that northern Santos Basin show evidences of an intensely deformed zone, where rift evolved under oblique extension, similar to that observed at transform margin segments.     

煤地质学研究进展与前沿

煤地质学是以煤的形成、组成、煤系伴生矿产、煤层瓦斯和煤层气为主要研究内容的地质学分支。近年来随着我国和世界对煤炭资源安全开采、洁净利用的要求逐渐提高,煤及煤层气资源的勘探与开发,煤地质学的研究重点也在逐渐发生变化。通过分析2011-2015年《国际煤地质学》杂志发表的717篇学术论文,总结了近期煤地质学最新的研究热点与前沿。研究发现：煤层气资源评价以及与煤层气开发关系最为紧密的煤储层物性研究是各国煤地质科技工作者最为关注的热点;煤中的矿物质和元素地球化学一直为人们所重视;与煤的形成、开采和利用相关的煤岩学及有机地球化学,煤的自燃、燃烧与环境,沉积环境与煤炭演化,地理信息系统与矿区环境监测,矿井瓦斯,矿井构造,矿井水和煤的热解等方面的研究一直在持续开展;页岩气资源评价与开发越来越受到人们重视。     

水文科学的基本问题及当代前沿

回顾了新中国70年来水文科学的发展历程。阐述了水文科学的基本问题及其当代前沿:水圈及其与地球其他圈层的界面过程；水文循环及人类活动对水文循环的扰动；水文学研究的特点及其方法论；水文知识的应用等。提出了划分水文科学分支学科的科学基础，建议将水文科学划分为普通水文学、水文气象学、陆地水文学、生态水文学和应用水文学5个分支学科。     

水文科学的基本问题及当代前沿

回顾了新中国70年来水文科学的发展历程。阐述了水文科学的基本问题及其当代前沿：水圈及其与地球其他圈层的界面过程；水文循环及人类活动对水文循环的扰动；水文学研究的特点及其方法论；水文知识的应用等。提出了划分水文科学分支学科的科学基础，建议将水文科学划分为普通水文学、水文气象学、陆地水文学、生态水文学和应用水文学5个分支学科。     

Geological investigations at a high altitude, remote coal mine on the Northwest Pakistan and Afghanistan frontier, Karakoram Himalaya

The Northwest Pakistan and Afghanistan frontier is located one of the most remote, inaccessible, and inhospitable part of the Himalayan orogenic belt. In this region, two of the world's largest and most distinct mountain belts intersect; the Karakoram Himalaya (mainly in Pakistan) and the Hindu Kush (mainly in Afghanistan). Located at high altitude, in a remote part of Northwest Pakistan, close to the border with Afghanistan, tribal villagers began excavating a series of adits into the steep mountain slopes, beneath glaciers, to extract valuable coal and carbonaceous shale resources. These were discovered in 1996, by the villagers, whilst hunting, and may represent some of the highest mine workings in the world. Small-scale mining operations subsequently developed using rudimentary mining methods and the mine became known as the Reshit or Pamir Coal Mine.The coal deposits are sedimentary, highly disturbed and tectonised, having been subjected to multiple phases of orogenic crustal deformation. The coal occurs as discrete lenses, several tens of metres in their lateral dimension, between steeply dipping, overturned and thrusted limestone beds of Jurassic age. The coal provided a vital, alternative source of fuel for the villagers since the local, traditional fuel supply was wood, which had become severely depleted, and imports of kerosene from neighbouring China and Afghanistan were too expensive.The mining operations experienced severe problems. These included several collapses of mine entrances, the failure of the adits to intersect the coal-bearing zones, the potential threat of geological hazards, mining-induced hazards and harsh high-altitude operating conditions, particularly during the winter months. International aid was provided to assist the villagers and a geological investigation was commissioned to investigate the problems at the mine.The geology of Karakoram Himalaya is relatively poorly understood. Until recently the region was restricted to foreign visitors and large areas of this mountain belt are virtually unmapped. Existing geological and topographic maps are difficult to obtain or are unavailable due to the close proximity of political frontiers, national borders and security reasons. The mineral resource potential of this region is virtually unknown. Few western geologists have visited this area due to its inaccessibility and political constraints, being situated close the frontiers with China, Afghanistan, and the disputed Pakistan and India territory of Kashmir.The Pakistan and Afghanistan border, is once again, now closed to foreign visitors. The objectives of this paper are to document the occurrence of coal and carbonaceous shale, at high altitude, in the Karakoram Himalaya and to provide details on the geology, geological hazards, reserves and labour-intensive mining operations. These observations and information may provide the basis for future mineral exploration, mining-geology, mining-engineering, feasibility studies and engineering geological investigation in the Karakoram Himalaya.     

Geological framework of the Brazilian continental margin

Based on distinctive stratigraphic and/or structural characteristics, the Brazilian continental margin can be divided into two main provinces:

1. The southeastern-eastern province, extending from the Pelotas to the Recife-João Pessoa Basin, presents a tensional tectonic style of Late Jurassic-Early Cretaceous age, paralleling the structural alignements of the Precambrian basement, except in the north-eastern segment where the Mesozoic faults of the Recife-João Pessoa Basin cut across the east-west basement directions. The basin-fill, Upper Jurassic through Recent, consists, where complete, of three stratigraphic sequences, each of a distinct depositional environment: (a) a lower clastic non-marine sequence; (b) a middle evaporitic sequence, and (c) an upper clastic paralic and open marine sequence.
2. The northern province, extending from the Potiguar Basin to the Amazon Submarine Basin, displays both tensional and compressional tectonic styles of Upper Jurassic (?) to Upper Cretaceous age either paralleling or cutting transversally the basement alignments. The stratigraphic column differs from the southeastern-eastern province in lacking the Lower Cretaceous evaporitic rocks.

The integration of the stratigraphie and structural data allows one to determine in the eastern Brazilian marginal basins the main evolutionary stages of a typical pull-apart continental margin: a continental pre-rift and rift stage, an evaporitic proto-ocean stage, and a normal marine open ocean stage. In the northern province it is possible to infer a continental rift-valley-stage, a transform stage and an open continental-margin stage. The relationship between the rift-valley and the transform stages is yet not clear.     

The state and the land question of the frontier — a geopolitical perspective

This paper analyzes the role played by the state in the expansion of the frontier from a geopolitical viewpoint. In this regard, emphasis will be placed on the question of access to the land as related to the work force mobility, a vital aspect for understanding geopolitical attitudes. Land-opening and migration policies will be considered in association with the implicit strategy of the state, as well as in its consequences for the expansion of the frontier in the E Amazon basin. A return to geopolitical analysis of the space seems opportune at a time when new policies of space management and territorial control are becoming more evident.     

Variability of mangrove ecosystems along the Brazilian coast

Brazilian mangroves extend from 4°30′N to 28°30′S, varying greatly in growth form, species distribution patterns, and stand structure, in spite of a limited floristic diversity. We divided the Brazilian coastline into eight units, within which physiographic and climatic conditions are relatively uniform, and described mangrove occurrence, species distribution and structural attributes characteristic of each segment. In general, greates mangrove coverage and greatest forest stature are found in areas with a large surplus of rainfall over potential evapotranspiration and macrotidal regimes. An exception was the segment containing the mouth of the Amazon river, where freshwater systems dominate over brackish or marine associations. We believe that the variability in species associations and the dominance of each in a given environment is predominantly determined by the characteristics of the landforms that can be colonized by each species in a given region. The type, size, and frequency of occurrence of available landforms is a function of the particular mix of fluvial, tidal, and wave energies found in a region. Different species colonize these sites depending on their adaptations and edaphic preferences. Climate affects mangrove colonization and growth. We suggest that Brazilian mangroves play a minor role in modifying the geomorphic setting; the spatial arrangement of the various forest types is a response to the underlying topography and edaphic conditions, and to the constraints imposed by climatic and hydrologic factors. The spatial arrangement of species does not necessarily show successional processes, but may be the result of direct and differential colonization on appropriate substrates.     

Undiscovered Petroleum of the Brazilian Interior Rift Basins

Brazil is estimated to contain 52% of the undiscovered oil and gas resources of South America, outside of Venezuela and Colombia. The Reconcavo, Tucano-Jatoba, and Tacutu interior rift basins of Brazil are investigated in this paper, the first in a series dealing with undiscovered petroleum of South America (exclusive of Venezuela and Colombia). Preliminary estimates of the undiscovered petroleum resources are 0.273 billion barrels of oil (BBO) and 1.234 trillion cubic feet of gas (TCFG) for the four basins. A review of the 1983-1993 history of petroleum reserves in South America indicated that an initial consensus estimate of 0.27 BBO and 4.15 TCFG (mean values) by the World Energy Program Group at the U.S. Geological Survey is too low. An adjusted range of probabilities is recalculated from original identified reserves, resulting in revised mean values of 0.29 BBO and 4.15 TCFG for the four interior rift basins. Of these four basins, the Reconcavo is in a mature stage of exploration with 80 fields; the other rift basins, as well as most of the other basins in Brazil, have not been as extensively investigated. In the Reconcavo basin, the principal plays are found in the pre-rift fault blocks, and in lower Cretaceous turbidites and sand lenses. Three gas fields are known in the southern Tucano subbasin. The three subbasins (southern, central, and northern) and the adjacent Jatoba basin become progressively less prospective northward because of lower levels of source-rock maturation. The plays in these basins are similar to those of the Reconcavo. The main play in the small Tacutu basin of northwestern Brazil is in deltaic sandstones; fractured basement rocks and volcanics constitute a minor play. The best reservoirs may be expected on the margins of the basin, although the reservoir seals are absent or poorly developed.     

Capitalist homoficience,the frontier and uneven development in Southern Africa

Frontier studies continue to be compromised by a double inadequacy. While geographers mistakenly cling to obsolete models of frontier process, those who have adopted a more progressive interactionist definition have difficulty conceptualizing the components and dimensions of interaction. The conceptual framework suggested by the literature on the articulation of modes of production is proposed as a partial resolution of the problem. Discarding the abstract and problematical notion of the mode of production as a useful tool for concrete analysis, attention is focused on the concepts and hypotheses suggested by the notion of articulation. It is proposed that in southern Africa, at least, this concept offers geographers a way forward which will circumvent the difficulties currently being experienced by the predominantly liberal interactionist school.     

The adversity of Brazilian drought

Drought-stricken NE Brazil is studied in the context of four regional units: the semiarid lowlands of the interior sertão, which have the maximum precipitation fluctuations; the well-watered Cariri valley, which experiences harvest shortages during abnormally dry years; the coastal fringe, which suffers during years of widespread drought; and the highlands of Baturite, where dry spells are noticed only through an influx of migrants from low-lying and drought-stricken areas.Adjustment to drought is, in general, low; it depends on the degree of drought awareness, which is also quite low. Affluent individuals are more inclined to make adjustments to droughts, although the likelihood of their being affected is less than among poor individuals. Middleclass individuals are more inclined to react to threats of an impending drought than to act under actual drought conditions. If age is taken into consideration, middle-aged individuals show greater awareness of drought conditions and a higher propensity to making adjustments than aged or youthful populations. Women are less inclined to make adjustments than men, and married people less than singles. Large families, probably compelled by the constraints, are especially prone to undertake changes in living conditions when a drought strikes.In general, the choices provided by economic feasibility, the possibilities of mitigating drought effects through technological know-how, and the social input of marriage and family size are very important parameters in shaping the character of the adjustments to drought.