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No caminho dos antigos: agricultura de corte-e-queima e intensificação agrícola em populações quilombolas do Vale do Ribeira, SP; On the old ones'track: shifting cultivation and agricultural intensification on quilombola populations at the Ribeira Valley, SP

Pedroso Junior, Nelson Novaes
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 05/09/2008 Português
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66.59%
A agricultura de corte-e-queima é praticada há milhares de anos nas áreas florestadas do planeta, principalmente nas regiões tropicais. Muitos estudos atestam a sustentabilidade desses sistemas quando praticados tradicionalmente e sob baixas densidades populacionais, mantendo, ou mesmo, promovendo a biodiversidade local e garantindo a subsistência de milhões de pessoas pobres rurais. No entanto, é crescente na literatura acadêmica e no debate político o papel que a agricultura de corte-e-queima vem desempenhando no desmatamento e demais impactos ambientais e sócio-econômicos. Esse processo é conseqüência das mudanças no uso do solo, intensificação agrícola e aumento demográfico que estão alterando as práticas e comprometendo a sustentabilidade desses sistemas agrícolas tradicionais. No Vale do Ribeira, sudeste do Estado de São Paulo, comunidades quilombolas têm sofrido um processo acelerado de mudanças nos seus padrões de subsistência. Dessa forma, esse estudo traz uma revisão da literatura sobre a agricultura de corte-equeima com o objetivo de traçar um panorama geral do que foi produzido até o momento, identificar as principais correntes teóricas envolvidas e apontar as alternativas propostas para sua manutenção. Em seguida...

Os efeitos da intensificação agrícola na comunidade de aves das estepes cerealíferas

Delgado, Ana Margarida dos Santos
Fonte: ISA Publicador: ISA
Tipo: Tese de Doutorado
Publicado em //2013 Português
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Doutoramento em Engenharia Florestal e dos Recursos Naturais - Instituto Superior de Agronomia; This study evaluates the agricultural intensification effects on steppe bird populations of cereal fields and fallows. Through the analysis of landscape dynamics between 2002–2011, a gradient of agricultural intensification was identified in selected areas of Baixo Alentejo. In cereal fields, total bird abundance of steppe and resident birds decreased along the intensification gradient. During the breeding season, this trend should be related to an increase in height and density of vegetation structure in intensive areas. Food availability is not influenced by intensification. In extensive areas, the bird abundance is influenced by differences associated to the type of cereal and vegetation structure. In fallows, the abundance of steppe and resident birds is affected by intensification. Wintering and breeding species are influenced by fallow age and livestock presence. The multi-scale analysis of local management and landscape composition effects on steppe bird community in cereal fields showed that local component is more important in winter. In fallows, both components are equally important for steppe bird community. Between-year variations (2002-2008) in Tetrax tetrax population densities were shown to be influenced by agricultural intensification and rainfall

Agricultural intensification and changes in cultivated areas, 1970–2005

Rudel, Thomas K.; Schneider, Laura; Uriarte, Maria; Turner, B. L.; DeFries, Ruth; Lawrence, Deborah; Geoghegan, Jacqueline; Hecht, Susanna; Ickowitz, Amy; Lambin, Eric F.; Birkenholtz, Trevor; Baptista, Sandra; Grau, Ricardo
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
Português
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46.66%
Does the intensification of agriculture reduce cultivated areas and, in so doing, spare some lands by concentrating production on other lands? Such sparing is important for many reasons, among them the enhanced abilities of released lands to sequester carbon and provide other environmental services. Difficulties measuring the extent of spared land make it impossible to investigate fully the hypothesized causal chain from agricultural intensification to declines in cultivated areas and then to increases in spared land. We analyze the historical circumstances in which rising yields have been accompanied by declines in cultivated areas, thereby leading to land-sparing. We use national-level United Nations Food and Agricultural Organization data on trends in cropland from 1970–2005, with particular emphasis on the 1990–2005 period, for 10 major crop types. Cropland has increased more slowly than population during this period, but paired increases in yields and declines in cropland occurred infrequently, both globally and nationally. Agricultural intensification was not generally accompanied by decline or stasis in cropland area at a national scale during this time period, except in countries with grain imports and conservation set-aside programs. Future projections of cropland abandonment and ensuing environmental services cannot be assumed without explicit policy intervention.

Pesticide Acute Toxicity Is a Better Correlate of U.S. Grassland Bird Declines than Agricultural Intensification

Mineau, Pierre; Whiteside, Mélanie
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 20/02/2013 Português
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Common agricultural birds are in decline, both in Europe and in North America. Evidence from Europe suggests that agricultural intensification and, for some species, the indirect effects of pesticides mediated through a loss of insect food resource is in part responsible. On a state-by-state basis for the conterminous Unites States (U.S.), we looked at several agronomic variables to predict the number of grassland species increasing or declining according to breeding bird surveys conducted between 1980 and 2003. Best predictors of species declines were the lethal risk from insecticide use modeled from pesticide impact studies, followed by the loss of cropped pasture. Loss of permanent pasture or simple measures of agricultural intensification such as the proportion of land under crop or the proportion of farmland treated with herbicides did not explain bird declines as well. Because the proportion of farmland treated with insecticides, and more particularly the lethal risk to birds from the use of current insecticides feature so prominently in the best models, this suggests that, in the U.S. at least, pesticide toxicity to birds should be considered as an important factor in grassland bird declines.

The compatibility of agricultural intensification in a global hotspot of smallholder agrobiodiversity (Bolivia)

Zimmerer, Karl S.
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
Português
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Integrating the conservation of biodiversity by smallholder farmers with agricultural intensification is increasingly recognized as a leading priority of sustainability and food security amid global environmental and socioeconomic change. An international research project investigated the smallholder agrobiodiversity of maize (corn) in a global hotspot (Bolivia) undergoing significant intensification. Peach-based intensification was pronounced (300–400%) and prolonged (2000–2010) in study areas. Intensification and maize agrobiodiversity were found to co-occur within smallholder landscapes. Interactions of these field systems did not trigger land-change tipping points leading to landrace extirpation. By 2010 maize landraces in the study areas still demonstrated high levels of taxonomic and ecological biodiversity and contributed significantly to this crop’s agrobiodiversity at national (31%) and hemispheric (3%) scales. Social and ecological resilience and in situ conservation of the maize agrobiodiversity by Bolivian smallholders was enabled through robust linkages to off-farm migration; resource access and asset capabilities among both traditional and nontraditional growers; landrace agroecology and food uses; and innovative knowledge and skills. The smallholders’ resilience resulting from these linkages was integral to the conditional success of the in situ conservation of maize agrobiodiversity. Environment–development interactions both enabled smallholders’ agrobiodiversity resilience and influenced the limits and vulnerability of agrobiodiversity. Scientific policy recommendations regarding land-use planning and sustainability analysis are targeted to specific Río+20 priorities for agrobiodiversity.

Agricultural intensification escalates future conservation costs

Phelps, Jacob; Carrasco, Luis Roman; Webb, Edward L.; Koh, Lian Pin; Pascual, Unai
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
46.84%
The supposition that agricultural intensification results in land sparing for conservation has become central to policy formulations across the tropics. However, underlying assumptions remain uncertain and have been little explored in the context of conservation incentive schemes such as policies for Reducing Emissions from Deforestation and forest Degradation, conservation, sustainable management, and enhancement of carbon stocks (REDD+). Incipient REDD+ forest carbon policies in a number of countries propose agricultural intensification measures to replace extensive “slash-and-burn” farming systems. These may result in conservation in some contexts, but will also increase future agricultural land rents as productivity increases, creating new incentives for agricultural expansion and deforestation. While robust governance can help to ensure land sparing, we propose that conservation incentives will also have to increase over time, tracking future agricultural land rents, which might lead to runaway conservation costs. We present a conceptual framework that depicts these relationships, supported by an illustrative model of the intensification of key crops in the Democratic Republic of Congo, a leading REDD+ country. A von Thünen land rent model is combined with geographic information systems mapping to demonstrate how agricultural intensification could influence future conservation costs. Once postintensification agricultural land rents are considered...

Zoonosis emergence linked to agricultural intensification and environmental change

Jones, Bryony A.; Grace, Delia; Kock, Richard; Alonso, Silvia; Rushton, Jonathan; Said, Mohammed Y.; McKeever, Declan; Mutua, Florence; Young, Jarrah; McDermott, John; Pfeiffer, Dirk Udo
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
Português
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56.59%
A systematic review was conducted by a multidisciplinary team to analyze qualitatively best available scientific evidence on the effect of agricultural intensification and environmental changes on the risk of zoonoses for which there are epidemiological interactions between wildlife and livestock. The study found several examples in which agricultural intensification and/or environmental change were associated with an increased risk of zoonotic disease emergence, driven by the impact of an expanding human population and changing human behavior on the environment. We conclude that the rate of future zoonotic disease emergence or reemergence will be closely linked to the evolution of the agriculture–environment nexus. However, available research inadequately addresses the complexity and interrelatedness of environmental, biological, economic, and social dimensions of zoonotic pathogen emergence, which significantly limits our ability to predict, prevent, and respond to zoonotic disease emergence.

Contribution of insect pollinators to crop yield and quality varies with agricultural intensification

Bartomeus, Ignasi; Potts, Simon G.; Steffan-Dewenter, Ingolf; Vaissière, Bernard E.; Woyciechowski, Michal; Krewenka, Kristin M.; Tscheulin, Thomas; Roberts, Stuart P.M.; Szentgyörgyi, Hajnalka; Westphal, Catrin; Bommarco, Riccardo
Fonte: PeerJ Inc. Publicador: PeerJ Inc.
Tipo: Artigo de Revista Científica
Publicado em 27/03/2014 Português
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56.43%
Background. Up to 75% of crop species benefit at least to some degree from animal pollination for fruit or seed set and yield. However, basic information on the level of pollinator dependence and pollinator contribution to yield is lacking for many crops. Even less is known about how insect pollination affects crop quality. Given that habitat loss and agricultural intensification are known to decrease pollinator richness and abundance, there is a need to assess the consequences for different components of crop production.

Governance, agricultural intensification, and land sparing in tropical South America

Ceddia, Michele Graziano; Bardsley, Nicholas Oliver; Gomez-y-Paloma, Sergio; Sedlacek, Sabine
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
Português
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46.69%
Tropical South America has forest resources of global significance but exhibits a relatively high rate of deforestation. As agricultural expansion remains the most important cause of forest loss and degradation there, it is important to understand its main drivers. In this paper we address two important questions: How do the quality of governance and agricultural intensification combine to impact the spatial expansion of agriculture? Which aspects of governance are more likely to ensure that agricultural intensification allows sparing land for nature? By distinguishing between conventional and environmental dimensions of governance (which includes also the establishment of protected areas), we investigate which of these two aspects, by interacting with the process of agricultural intensification, is likely to promote land sparing.

Weakening density dependence from climate change and agricultural intensification triggers pest outbreaks: a 37-year observation of cotton bollworms

Ouyang, Fang; Hui, Cang; Ge, Saiying; Men, Xin-Yuan; Zhao, Zi-Hua; Shi, Pei-Jian; Zhang, Yong-Sheng; Li, Bai-Lian
Fonte: Blackwell Publishing Ltd Publicador: Blackwell Publishing Ltd
Tipo: Artigo de Revista Científica
Português
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46.62%
Understanding drivers of population fluctuation, especially for agricultural pests, is central to the provision of agro-ecosystem services. Here, we examine the role of endogenous density dependence and exogenous factors of climate and human activity in regulating the 37-year population dynamics of an important agricultural insect pest, the cotton bollworm (Helicoverpa armigera), in North China from 1975 to 2011. Quantitative time-series analysis provided strong evidence explaining long-term population dynamics of the cotton bollworm and its driving factors. Rising temperature and declining rainfall exacerbated the effect of agricultural intensification on continuously weakening the negative density dependence in regulating the population dynamics of cotton bollworms. Consequently, ongoing climate change and agricultural intensification unleashed the tightly regulated pest population and triggered the regional outbreak of H. armigera in 1992. Although the negative density dependence can effectively regulate the population change rate to fluctuate around zero at stable equilibrium levels before and after outbreak in the 1992, the population equilibrium jumped to a higher density level with apparently larger amplitudes after the outbreak. The results highlight the possibility for exogenous factors to induce pest outbreaks and alter the population regulating mechanism of negative density dependence and...

Impacts de l’intensification agricole et de la structure du paysage sur les relations tri – trophiques entre un oiseau hôte, des mouches ectoparasites et leur parasitoïdes.

Daoust, Simon P.
Fonte: Université de Montréal Publicador: Université de Montréal
Tipo: Thèse ou Mémoire numérique / Electronic Thesis or Dissertation
Português
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L’intensification des pratiques agricoles a été identifiée comme cause majeure du déclin de la biodiversité. Plusieurs études ont documenté l’impact de la fragmentation du paysage naturel et de l’agriculture intensive sur la diversité des espèces, mais très peu ont quantifié le lien entre la structure du paysage et les interactions trophiques, ainsi que les mécanismes d’adaptation des organismes. J’ai étudié un modèle biologique à trois niveaux trophiques composé d’un oiseau hôte, l’hirondelle bicolore Tachycineta bicolor, de mouches ectoparasites du genre Protocalliphora et de guêpes parasitoïdes du genre Nasonia, au travers d’un gradient d’intensification agricole dans le sud du Québec. Le premier objectif était de déterminer l’abondance des espèces de mouches ectoparasites et de leurs guêpes parasitoïdes qui colonisent les nids d’hirondelles dans la zone d’étude. La prévalence de nids infectés par Protocalliphora spp. était de 70,8% en 2008 et 34,6% en 2009. Le pourcentage de nids comprenant des pupes de Protocalliphora parasitées par Nasonia spp. était de 85,3% en 2008 et 67,2% en 2009. Trois espèces de Protocalliphora ont été observées (P. sialia, P. bennetti et P. metallica) ainsi que deux espèces de Nasonia (N. vitripennis et N. giraulti). Il s’agit d’une première mention de P. bennetti et de N. giraulti dans la province de Québec. Mon deuxième objectif était d’évaluer l’impact de l’intensification agricole et de la structure du paysage sur les relations tri-trophiques entre les organismes à l’étude. Les résultats révèlent que les réponses à la structure du paysage de l’hirondelle...

Agricultural intensification escalates future conservation costs

Phelps, J.; Carrasco, L.; Webb, E.; Koh, L.; Pascual, U.
Fonte: Natl Acad Sciences Publicador: Natl Acad Sciences
Tipo: Artigo de Revista Científica
Publicado em //2013 Português
Relevância na Pesquisa
46.84%
The supposition that agricultural intensification results in land sparing for conservation has become central to policy formulations across the tropics. However, underlying assumptions remain uncertain and have been little explored in the context of conservation incentive schemes such as policies for Reducing Emissions from Deforestation and forest Degradation, conservation, sustainable management, and enhancement of carbon stocks (REDD+). Incipient REDD+ forest carbon policies in a number of countries propose agricultural intensification measures to replace extensive “slash-and-burn” farming systems. These may result in conservation in some contexts, but will also increase future agricultural land rents as productivity increases, creating new incentives for agricultural expansion and deforestation. While robust governance can help to ensure land sparing, we propose that conservation incentives will also have to increase over time, tracking future agricultural land rents, which might lead to runaway conservation costs. We present a conceptual framework that depicts these relationships, supported by an illustrative model of the intensification of key crops in the Democratic Republic of Congo, a leading REDD+ country. A von Thünen land rent model is combined with geographic information systems mapping to demonstrate how agricultural intensification could influence future conservation costs. Once postintensification agricultural land rents are considered...

Sustainable agricultural intensification or Jevons paradox? The role of public governance in tropical South America

CEDDIA Michele Graziano; SEDLACEK S; BARDSLEY N. O.; GOMEZ Y PALOMA Sergio
Fonte: ELSEVIER SCI LTD Publicador: ELSEVIER SCI LTD
Tipo: Articles in Journals Formato: Online
Português
Relevância na Pesquisa
46.59%
The process of global deforestation calls for urgent attention, particularly in South America where deforestation rates have failed to decline over the past 20 years. The main direct cause of deforestation is land conversion to agriculture. We combine data from the FAO and the World Bank for six tropical Southern American countries over the period 1970–2006, estimate a panel data model accounting for various determinants of agricultural land expansion and derive elasticities to quantify the effect of the different independent variables. We investigate whether agricultural intensification, in conjunction with governance factors, has been promoting agricultural expansion, leading to a ‘‘Jevons paradox’’. The paradox occurs if an increase in the productivity of one factor (here agricultural land) leads to its increased, rather than decreased, utilization. We find that for high values of our governance indicators a Jevons paradox exists even for moderate levels of agricultural productivity, leading to an overall expansion of agricultural area. Agricultural expansion is also positively related to the level of service on external debt and population growth, while its association with agricultural exports is only moderate. Finally...

Governance, agricultural intensification, and land sparing in tropical South America

CEDDIA Michele Graziano; BARDSLEY N. O.; GOMEZ Y PALOMA Sergio; SEDLACEK S
Fonte: NATL ACAD SCIENCES Publicador: NATL ACAD SCIENCES
Tipo: Articles in Journals Formato: Online
Português
Relevância na Pesquisa
46.86%
In this paper we address two topical questions: How do the quality of governance and agricultural intensification impact on spatial expansion of agriculture? Which aspects of governance are more likely to ensure that agricultural intensification allows sparing land for nature? Using data from the Food and Agriculture Organization, the World Bank, the World Database on Protected Areas, and the Yale Center for Environmental Law and Policy, we estimate a panel data model for six South American countries and quantify the effects of major determinants of agricultural land expansion, including various dimensions of governance, over the period 1970– 2006. The results indicate that the effect of agricultural intensification on agricultural expansion is conditional on the quality and type of governance. When considering conventional aspects of governance, agricultural intensification leads to an expansion of agricultural area when governance scores are high. When looking specifically at environmental aspects of governance, intensification leads to a spatial contraction of agriculture when governance scores are high, signaling a sustainable intensification process.; JRC.J.4-Agriculture and Life Sciences in the Economy

Agricultural Intensification : The Status in Six African Countries

Binswanger-Mkhize, Hans P.; Savastano, Sara
Fonte: World Bank Group, Washington, DC Publicador: World Bank Group, Washington, DC
Tipo: Publications & Research :: Policy Research Working Paper; Publications & Research
Português
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56.84%
The Boserup-Ruthenberg framework has long been used to explain and understand the determinants of agricultural growth, the nature of the intensification of farming systems, investment, and technology adoption. The literature has produced an extensive body of evidence that summarizes or tests the hypothesis in Africa and often found it confirmed. However, in the past two decades, rapid population growth has put African farming systems under stress. At the same time, there has been a sharp increase in urbanization and economic growth that is providing new market opportunities for farmers. It is therefore necessary to investigate whether this has resulted in rapid intensification of farming systems, permitting rapid agricultural growth and maintenance or increase in the incomes of the farming population. This paper describes the status of intensification in six African countries using the first round of data from the Living Standards Measurement Study-Integrated Surveys on Agriculture. In addition, the paper (i) develops internationally comparable measures of overall agro-ecological crop potential and urban gravity in the farmers' location and (ii) estimates the causal impact of agro-ecological potential and urban gravity on population density...

Household expansion linked to agricultural intensification during emergence of Hawaiian archaic states

Field, Julie S.; Ladefoged, Thegn N.; Kirch, Patrick V.
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
46.59%
The Leeward Kohala Field System (LKFS) covering ∼60 km2 on Hawai‘i Island is one of the world's best-studied archaeological examples of preindustrial agricultural intensification. Archaeological correlates for households over a 400-y period of intensification of the LKFS (A.D. 1400–1800) indicate that household age, number, and distribution closely match the expansion of agricultural features at both macro- and microscales. We excavated and dated residential complexes within portions of five traditional Hawaiian land units (ahupua‘a), two in the central core of the field system and three in the southern margins. Forty-eight radiocarbon dates from 43 residential features indicate an overall pattern of exponential increase in the numbers of households over time. Spatial distribution of these dates suggests that the core of the LKFS may have reached a population saturation point earlier than in the southern margins. Bayesian statistical analysis of radiocarbon dates from residential features in the core region, combined with spatial analysis of agricultural and residential construction sequences, demonstrates that the progressive subdivision of territories into smaller socioeconomic units was matched by addition of new residences...

Effects of agricultural intensification on ability of natural enemies to control aphids

Zhao, Zi-Hua; Hui, Cang; He, Da-Han; Li, Bai-Lian
Fonte: Nature Publishing Group Publicador: Nature Publishing Group
Tipo: Artigo de Revista Científica
Publicado em 26/01/2015 Português
Relevância na Pesquisa
46.76%
Agricultural intensification through increasing fertilization input and cropland expansion has caused rapid loss of semi-natural habitats and the subsequent loss of natural enemies of agricultural pests. It is however extremely difficult to disentangle the effects of agricultural intensification on arthropod communities at multiple spatial scales. Based on a two-year study of seventeen 1500 m-radius sites, we analyzed the relative importance of nitrogen input and cropland expansion on cereal aphids and their natural enemies. Both the input of nitrogen fertilizer and cropland expansion benefited cereal aphids more than primary parasitoids and leaf-dwelling predators, while suppressing ground-dwelling predators, leading to an disturbance of the interspecific relationship. The responses of natural enemies to cropland expansion were asymmetric and species-specific, with an increase of primary parasitism but a decline of predator/pest ratio with the increasing nitrogen input. As such, agricultural intensification (increasing nitrogen fertilizer and cropland expansion) can destabilize the interspecific relationship and lead to biodiversity loss. To this end, sustainable pest management needs to balance the benefit and cost of agricultural intensification and restore biocontrol service through proliferating the role of natural enemies at multiple scales.

Intensification, social production and the inscrutable ways of culture

Gardner, Don
Fonte: Blackwell Publishing Ltd Publicador: Blackwell Publishing Ltd
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
46.72%
This paper examines Harold Brookfield's crucial concept of social production in the debates about the development of, and differences between, agricultural systems in central New Guinea. Although it was first explicity elaborated by this eminent geographer, a striking feature of this concept is its appeal to a wide range of disciplinary specialists. No less striking is the degree to which it coheres with anthropological conceptions of culture as a realm of meaning marked by arbitrariness; consequently, culture is taken to possess an endogenous dynamic (or a 'logic') that gives it the role of an independent variable in the historical process. Social production, therefore, signals analytical concerns to avoid what are taken to reductionist accounts of agricultural transitions. I offer a deflationary account of social production that would make it more amenable to a naturalistic, interactionist perspective on culture and historical process; by reconstruing the cultural as the relatively micro-historical it is more easily reconciled with macro-historical narratives concerning intensification in central New Guinea.

Boserup and Brookfield and the association between population density and agricultural intensity in Papua New Guinea

Allen, Bryant
Fonte: Blackwell Publishing Ltd Publicador: Blackwell Publishing Ltd
Tipo: Artigo de Revista Científica
Português
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Data from a 1990-96 nationwide study of Papua New Guinea systems - the Mapping Agricultural Systems in PNG study (MASP) - is used to re-examine Brookfield with Hart's (1971) findings on the association between agricultural intensity and population density in Papua New Guinea. A significant association exists between these variables, both within the MASP data, and within the agricultural systems examined by Brookfield with Hart, when the MASP data is applied to them. However, a large amount of variation exists in the data. Systems in which 'mismatches' occur between population density and agricultural intensity are found to be associated with small island environments, the substitution of purchased food for locally produced food, migration and high levels of child malnutrition. Child malnutrition may be one of the consequences of a failure to innovate and thus maintain food production. It is argued that Boserup's (1965) model of agricultural transformation and Brookfield's past work on intensification which he now downplays, continue to provide valuable insights into agricultural change in contemporary Papua New Guinea.

Intensification of agricultural systems in Papua New Guinea

Bourke, Mike
Fonte: Blackwell Publishing Ltd Publicador: Blackwell Publishing Ltd
Tipo: Artigo de Revista Científica
Português
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46.74%
This paper provides an overview of the ways in which villagers have intensified agricultural systems in Papua New Guinea, focusing on the last 60 years. The intensification techniques used by villagers include: adoption of more productive staple crops, in particular sweet potato, cassava, Xanthosoma taro, Solanum potato and maize; adoption of more productive cultivars, especially of banana and sweet potato; shortening the fallow period; extending the cropping period; certain soil fertility maintenance techniques, other than natural regrowth fallows (composting, managed tree fallows, especially using casuarina, a legume/root crop rotation, and soil erosion control); and some other intensification techniques including soil tillage, drainage, construction of garden beds, garden segregation, mounding and irrigation. People often use more than one technique and the techniques used vary between the major agricultural zones. The adoption of new food crops and more productive cultivars of existing food crops has facilitated many of the other changes, particularly longer cropping periods and shorter fallow periods.