31 |
A construção social do mercado de acácia-negra no estado do Rio Grande do Sul / Social construction of market of acacia mearnsii in the state of Rio Grande do SulLisboa, Rodrigo da Silva 13 September 2013 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / For a long time the markets were seen as an abstract entity, regulated by offer and demand
for products, and disconsidered the importance of social interaction in their formation.
Therefore, this study aimed to comprehend the factors that contributed to and conditioned
the shape of the market structure of Acacia mearnsii De Wild in Rio Grande do Sul, as well
as understand the different roles of agents and institutions in the social construction of this
market. This work specifically intended: identify agents that compose the market for Acacia
mearnsii and their roles; map the network of relationships of the agents in the market;
understand the effect of social, technical, economic and political aspects in the development
of market of Acacia mearnsii in Rio Grande do Sul. For this was selected the New Economic
Sociology (NES) as the theoretical basis. Pierre Bordieu was the main visited author, due of
his theory of fields and capital, and for understand that the action of agents is conditioned by
the existent structure and the structure is conditioned by the habitus of agents. Other authors
such as Fligstein, Swedberg, Steiner and Abramovay also have meaningful participation in
the study due to their contributions to the area. The methodology used to conduct this study
was the case study, and the market of Acacia mearnsii was considered the case to be
analyzed. To obtain the data, semi-structured interviews were realized in ten cities of RS,
with the main companies of the sector, along forest producers that operate in different ways
and with different strategies, and with the company Technical Assistance and Rural
Extension (TARE). As a secondary source, we used data of IBGE, Emater / Ascar and
various agencies connected with the section. Thus, it was concluded that the market of
Acacia mearnsii is a social construct composed of several agents, identified eleven kinds,
each with distinct characteristics and strategies. It was noticed that this market had its
beginning promoted by the exploration of the shell for the production of tannin. In a second
moment, comes the production of charcoal, the main way to use the wood until the 1990s,
and from 1995 began the exploration of wood for the purpose of producing splinter for export,
considerably modifying the field. It was also noticed that this market was conditioned by
several factors such as the concentration of capital from major companies; the influence of
formal and informal institutional environment on the action of the agents, materialized by
environmental and labor laws and culture; the lack of labor, indifferently of the size of the
producer; the problem of the succession of family foresters; the lack of cooperation between
small producers to market their products; the ability of social enterprises and their influence
on other agents; habitus colonist forester and coal producer, among others. / Por muito tempo os mercados foram entendidos como uma entidade abstrata, regulada pela
oferta e pela demanda dos produtos, e que desconsiderava a importância da interação
social na sua formação. Assim, este trabalho teve como objetivo geral compreender os
fatores que concorreram e que condicionaram o formato da estrutura do mercado da acácianegra
(Acacia mearnsii De Wild) no Rio Grande do Sul, bem como entender os distintos
papéis dos agentes e das instituições na construção social deste mercado. Especificamente
pretendeu-se: identificar os agentes que compõem o mercado de acácia-negra e seus
papéis; mapear a rede de relações dos agentes existente no mercado; compreender o efeito
dos aspectos sociais, técnicos, econômicos e políticos no desenvolvimento do mercado da
acácia-negra no Rio Grande do Sul (RS). Para isto selecionou-se a Nova Sociologia
Econômica (NSE) como o arcabouço teórico de base. O principal autor visitado foi Pierre
Bourdieu, em virtude da sua teoria dos campos e dos capitais, e por entender que a ação
dos agentes é condicionada pela estrutura existente e a estrutura é condicionada pelo
habitus dos agentes. Outros autores como Fligstein, Swedberg, Steiner e Abramovay
também tiverem participação destacada no estudo devido às suas contribuições para a área.
A metodologia utilizada para a realização deste trabalho foi o estudo de caso, sendo que o
mercado da acácia-negra foi considerado o caso a ser analisado. Para a obtenção dos
dados, foram realizadas entrevistas semiestruturadas, em dez municípios do estado do RS,
junto às principais empresas do setor, junto a produtores florestais que atuam de distintas
formas e com estratégias diferentes, e juntamente à empresa de Assistência Técnica e
Extensão Rural (ATER). Como fonte secundária, foram utilizados dados do IBGE, da
Emater/Ascar e de diversos órgãos ligados ao setor. Desta forma, concluiu-se que o
mercado da acácia-negra constitui uma construção social composta por diversos agentes,
sendo identificados onze tipos, cada um com características e estratégias distintas.
Percebeu-se que este mercado teve seu início impulsionado pela exploração da casca
destinada à produção de tanino. Em um segundo momento, surge a produção de carvão
vegetal, principal forma de utilizar a madeira até os anos 1990 e, a partir de 1995, iniciou-se
a exploração da madeira com a finalidade de produzir cavaco para exportação, modificando
consideravelmente o campo. Também notou-se que este mercado foi condicionado por
vários fatores, como a concentração dos principais capitais junto às empresas; a influência
do ambiente institucional formal e informal sobre a ação dos agentes, materializado pelas
legislações ambientais e trabalhistas e pela cultura; a falta de mão de obra, indiferentemente
do porte do produtor; o problema da sucessão dos silvicultores familiares; a falta de
cooperação entre os pequenos produtores para a comercialização de seus produtos; a
habilidade social das empresas e a sua influência sobre os demais agentes; o habitus do
colono silvicultor e produtor de carvão, entre outros.
|
32 |
Escarificação mecânica com areia para superação de dormência em sementes de acácia-negra (Acacia mearnsii De Wild.) / Mecanical scarification using sand to breack dormancy in black-wattle seeds (Acacia mearnsii De Wild.)Alves, Gilberto Demari 26 August 2008 (has links)
Made available in DSpace on 2014-08-20T13:44:41Z (GMT). No. of bitstreams: 1
tese_gilberto_alves.pdf: 5811235 bytes, checksum: 79599512dd0f6a38e1c722c6d54e659a (MD5)
Previous issue date: 2008-08-26 / The black wattle (Acacia mearnsii De Wild.) is, the third forest specie of larger economical
importance, more than 189 thousand ha are cultivated now, in Rio Grande do Sul, Brazil.
According its socio-environmental importance it can be considerate the first in importancy in
this state regarding the enormous benefits given to the black-wattle grower and to the
environment, such as: regenerator of degraded soils specie; short life pioneering specie;
quickly covering the soil; not presenting stump sprouting; it doesn't inhibit the local
succession and the high deposition of their nitrogen rich leaves, cause the enriching of the
soil. Black wattle has also the capacity of making symbiosis with microorganisms fixatives of
atmospheric nitrogen. Producing quality wood for energy and cellulose; the tannin extracted
from its peel is used for leather curing industry and in wines and beers clarification. More or
less 60% of black wattle growers are of small producers, about 40 thousand families live
from that activity. One of the limiting factors in the uniformity of the black-wattle's seedlings
production is the low of quality of their seeds. The quality of the seedlings and the forest
produced by them will depend on the dormancy and on the method used for its break. With
the objective of accelerating and standardization of the germination in the process of
seedlings production, we went after an alternative method that should be more practical and
efficient, in the break of black-wattle s seed dormancy. To reach these objectives the
mechanical scarification method was tested, using sand to polish as scarificant material and
the model GDA-8 escarificator. This GDA-8 scarificator was developed as part of the
research project during Post Graduation Program in Science and Technology of Seeds of
FAEM (Faculdade de Agronomia Eliseu Maciel) / UFPEL, by comparing it to the
conventional method that uses hot water. The black-wattle seeds used in this research are
originated from trees that were three, four, five and six years old, in Joca Tavares district in
Bagé / RS. Scarification was made using the following proportion: one part of seeds was
used to three parts of sand with thin granularity average of 0,75 mm, for 1 1/2 minute.
Mechanical damage, germination, first counting and weight of green and dry matter tests were
developed, in the Laboratory of Analysis of Seeds of FAEM and Emergency and Emergency
Velocity Index (IVG) in the vegetation home of Votorantim Cellulose and Paper s
dependences, located in Capão do Leão/RS municipal district. The random experimental
work was with three repetitions and the averages compared by the test of Tukey at the level of
5%. / A acácia negra (Acacia mearnsii De Wild.) é a terceira espécie florestal de maior
importância econômica para o RS, no qual são cultivados mais de 189 mil ha atualmente.
Considerando-se a importância sócio-ambiental, é a primeira neste estado, haja vista os
enormes benefícios auferidos pelos acacicultores e ao meio ambiente, como: espécie
recuperadora de solos degradados, espécie pioneira de vida curta, que cobre rapidamente o
solo, não apresenta rebrota de cepa, não inibe a sucessão local e enriquece o solo pela elevada
deposição de folhedo rico em nitrogênio. Também tem capacidade de efetuar simbiose com
microrganismos fixadores de nitrogênio atmosférico. Produz madeira de qualidade para
energia e celulose, de sua casca é extraído o tanino usado na indústria, desde o curtimento de
couros, até clarificação de vinhos e cervejas. Cerca de 60 % dos acacicultores, da região
produtora, são pequenos produtores, e 40 mil famílias vivem dessa atividade. Um dos fatores
limitantes na produção de mudas uniformes de acácia negra é a baixa qualidade de suas
sementes. Da dormência e do método utilizado para a sua superação, dependerá a qualidade
das mudas e das florestas produzidas por estas sementes. Com o objetivo de acelerar e
padronizar a germinação no processo de produção de mudas, buscou-se estudar um método
alternativo que fosse prático e eficiente, na superação da dormência em sementes de acácia
negra. Para alcançar estes objetivos, foi testado o método de escarificação mecânica,
utilizando-se areia como material escarificante e, escarificador modelo GDA-8, concebido
como parte do projeto de pesquisa desenvolvido durante o P.P.G. em Ciência e Tecnologia de
Sementes da FAEM / UFPEL comparado ao método convencional que utiliza água quente.
As sementes de acácia-negra, utilizadas nesse trabalho, foram provenientes de cultivos com
três, quatro, cinco e seis anos, localizados no distrito de Joca Tavares em Bagé / RS. Para a
escarificação, usou-se a proporção de uma parte de sementes para três de areia com
granulometria fina, com média de 0,75 mm, durante um minuto e meio. Foram realizados
testes de dano mecânico, germinação, primeira contagem e peso de matéria verde e seca, no
Laboratório de Análise de Sementes da FAEM e Emergência e Índice de Velocidade de
Emergência em casa de vegetação nas dependências da Votorantin Celulose e Papel,
localizada no município de Capão do Leão / RS. O delineamento experimental foi o
inteiramente casualisado, com três repetições e as médias comparadas pelo teste de Tukey ao
nível de 5 %.
|
33 |
A predictive biogeography of selected alien plant invaders in South AfricaYouthed, Jennifer Gay January 1997 (has links)
Five techniques were used to predict the potential biogeography of the four alien plant species, Acacia longifolia, Acacia mearnsii, Opuntia ficus-indica and Solanum sisymbrifolium. Prediction was based on five environmental factors, median annual rainfall, co-efficient of variation for rainfall, mean monthly maximum temperature for January, mean monthly minimum temperature for July and elevation. A geographical information system was used to manage the data and produce the predictive maps. The models were constructed with presence and absence data and then validated by means of an independent data set and chisquared tests. Of the five models used, three (the range, principal components analysis and discriminant function analysis) were linear while the other two (artificial neural networks and fuzzy logic) were non-linear. The two non-linear techniques were chosen as a plant's response to its environment is commonly assumed to be non-linear. However, these two techniques did not offer significant advantages over the linear methods. The principal components analysis was particularly useful in ascertaining the variables that were important in determining the distribution of each species. Artifacts on the predictive maps were also proved useful for this purpose. The techniques that produced the most statistically accurate validation results were the artificial neural networks (77% correct median prediction rate) and the discriminant function analysis (71% correct median prediction rate) while the techniques that performed the worst were the range and the fuzzy classification. The artificial neural network, discriminant function analysis and principal component analysis techniques all show great potential as predictive distribution models.
|
34 |
The long-term measurement of total evaporation over Acacia mearnsii using large aperture scintillometryClulow, Alistair D. January 2007 (has links)
A large aperture scintillometer (LAS) was operated continuously over a distance of 575 m from 19 August 2006 to 29 September 2007 in the South African KwaZulu-Natal midlands mistbelt area over Wattle (Acacia mearnsii). The LAS measurements of the structure parameter of the refractive index of air ( 2 n C ), were used to calculate the sensible heat flux. The shortened energy balance equation was used to estimate the latent energy flux as a residual from which the total evaporation (ET) was calculated. The LAS estimates of sensible heat flux during the short transition period (1 hour) between stable and unstable conditions were on occasion erroneous and required verification. Advection was also found to affect sensible heat flux estimates. Long-term operation of the LAS was however found to be possible even at remote sites, producing reliable and continuous results. The LAS estimates of sensible heat are sensitive to zero-plane displacement height and wind speed data impact and these should be derived as accurately as possible. Tree heights were measured at monthly intervals and a zero-plane displacement and effective height were calculated every two weeks. The sensible heat flux was thus processed in two week blocks of data corresponding to progressive effective heights. The tree growth rate was consistent over time and was not affected by seasonality, indicating that reduced air temperatures, rainfall and solar irradiance in winter are not limiting growth. The average growth rate was 0.37 m per month or 4.5 m per year. The LAS ET was compared to the American Society of Civil Engineers - Environmental and Water Resources Institute (ASCE-EWRI) short grass reference evaporation (ETsz) for a seven-month period and was found to compare favourably (R2 = 0.78) with outliers caused by advection and rainfall events. Calculations of grass reference evaporation at hourly and daily intervals provide different results. The daily estimates are lower than the hourly estimates by 17 % on average. Where hourly data is summed to calculate a daily ETsz, night-time values should be included. The LAS ET measurements were validated against the Priestley and Taylor (1972) method of estimating ET and found to be in good agreement (R2=0.94). The Priestley and Taylor daily total latent energy flux, from 22 August 2006 to 29 September 2007, was 9 % higher than the LAS results on average. The Bowen ratio for the entire period is less than 1, indicating that the latent energy flux dominates at the site. The ET over the period of measurement (13 months) is 1250 mm and the rainfall is 750 mm. This confirms previous results at the site using the Bowen ratio energy balance method showing that the ET exceeds the rainfall by 45 % and justifies further research into soil water, ground water and root interactions in the deep soil profile. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2007.
|
35 |
Effects of removing Acacia Mearnsii on the water table, soil and vegetation properties in the Tsomo Valley of the Eastern Cape Province, South AfricaMoyo, Hloniphani Peter Mthunzi January 2010 (has links)
No description available.
|
36 |
The influence of Acacia Mearnsii invasion on soil properties in the Kouga Mountains, Eastern Cape, South AfricaVan der Waal, Benjamin Wentsel January 2010 (has links)
The invasion of Acacia mearnsii in the Kouga catchment, Eastern Cape, South Africa, has various negative impacts on the ecosystem. These impacts include: reduced species richness, increased water use, increased nutrients and increased N cycling rates. The native shrubby fynbos vegetation has adapted to the acidic nutrient poor soils and Mediterranean climate of the Kouga Mountains. Fynbos, however, is currently being out competed by the much taller Acacia mearnsii trees, due to their competitive nature and ability to fix nitrogen, thereby enriching the soil. The invaded sections of the valley bottoms and lower hill slopes are characterised by an almost complete monoculture of Acacia mearnsii, with very few fynbos species still present. The Department of Water and Environmental Affairs sponsored Working for Water programme started clearing Acacia mearnsii in 1996 in the Kouga Mountains. Cleared sites have remained bare for long periods, indicating that soil properties are not favourable for indigenous propagule re-establishment. The aim of this research was to assess how A. mearnsii invasion and clearing affect fynbos recovery through its impact on soils. This was done by characterising vegetation and soil properties on fynbos, infested and cleared slopes. Vegetation cover for various growth forms was determined and a species list was compiled for each plot. The slope angle, surface hardness, litter cover, bare ground cover and soil depth were measured in the field, whereas water repellency, particle size and the chemical composition were measured in the laboratory. Furthermore, the plant establishment capacity of soils from fynbos, infested and cleared slopes was calculated. This was done by germinating fynbos seeds and growing fynbos plants in soils from the various slopes. The effect that invasion and clearing has on soil erosion was quantified using erosion plots on fynbos, infested and cleared slopes. The invasion and clearing of Acacia mearnsii led to an increase in soil nutrients, especially nitrogen, phosphorus, potassium, carbon and manganese. Furthermore, soils became more acidic, with increased water repellency and reduced surface hardness. The vegetation changed to a tree-dominated structure, replacing the native species. Native plant germination was relatively unaffected by invasion and clearing, with an increase in germination just after clearing. Plant growth of a native grass, Themeda triandra, and herb, Helichrysum umbraculigerum, has increased on soils from cleared slopes. This study showed that soil movement increased on slopes which are invaded and cleared of Acacia mearnsii, with erosion rates doubling on invaded slopes
|
37 |
On the implementation effectiveness and efficiency of ecological interventions in operational contexts : the case of Working for WaterMcConnachie, Matthew Morgan January 2013 (has links)
There is little understanding of the implementation efficiency and effectiveness of restoring plant invaded landscapes within operational contexts. South Africa's Working for Water (WfW) programme is arguably the most ambitious alien plant control programme in the world, yet little is known about its cost-effectiveness and the challenges it faces in linking poverty and environmental objectives. My first aim was to assess the cost-effectiveness of invasive plant removal, and the factors that underpin its effectiveness over large spatial and temporal scales. The second aim was to compare the accuracy of evidence-based findings with managers' experience-based beliefs, and to assess whether managers are willing to change their beliefs after being exposed to it. The third aim was to assess the costs and benefits of removal versus removal followed by active native re-vegetation. My final aim is to assess the challenges and lessons learnt by managers linking ecological restoration with poverty alleviation objectives, specifically within the public works model. My study area was focused primarily on two WfW river catchment projects in the western region of the Eastern Cape province. I adopted an interdisciplinary approach drawing from a range of methods such as observational studies, statistical modelling and interviews with managers. The key findings were that control efforts in the two catchment projects are largely inadequate owing to many sites being re-invaded and not enough resources being allocated to the catchments. It would take between 54 and 695 years to clear the respective catchments. In terms of cost-effectiveness, my results exceeded previous estimates by 1.5 to 8.6 times for each catchment project. After being exposed to the evidence-based findings, the managers did not change their beliefs when it came to forecasting the future effectiveness. I found that active native re-vegetation after removal of invasive plants is very costly and that priority should be given to understanding the effectiveness of the removal treatments on native species recovery. The managers cited significant challenges in effectively and efficiently meeting the programmes dual objectives. Based on a broader review of the public works literature I recommend WfW re-examine the type of public works they currently use.
|
38 |
A fluvial geomorphological study of river rehabilitation in the Kouga region, Eastern CapePietersen, Adrian January 2009 (has links)
The Kouga Riparian Rehabilitation Project (KRRP) is seen as a pilot rehabilitation project in the Kouga region that is heavily invaded with Acacia mearnsii along the riparian zones of many mountain streams. Clearing of these black wattles and re-planting of indigenous vegetation are imperative to rehabilitation efforts. In this context, two invaded catchments were identified - the Baviaans and the Heuningnes. The aim of this research is to characterise the effects that the woody alien invasive Acacia mearnsii has had on the river channel morphology of the Baviaans and Heuningnes Rivers. A desktop and initial field analysis of the relevant study area catchments was completed. This was followed by a comparison of the channel morphology of the various study channel reaches using fixed channel transects. Ecological resource quality objectives (RQOs) for river rehabilitation from a fluvial geomorphological viewpoint were then established. A long-term monitoring protocol to assess whether or not these RQOs will be achieved was recommended. Follow-up channel transects were measured post wattle clearance in the Baviaans and short-term (<2yrs) changes in channel form were described. Differences in terms of the effect of Acacia mearnsii on channel form were then interpreted by direct comparison and through statistical analysis. Results indicate a number of significant differences between those channels impacted by black wattle infestation and those channels seen as unimpacted and natural. Short-term changes (<2yrs) that occurred within the study period post Baviaans wattle clearance were shown to be minimal for channel form as well as for bed material. The lack of any clear relationship or explanation between channel form and other channel controls suggests vegetation as the primary control. Vegetation, specifically the invasive alien vegetation, is the key controlling variable acting on channel form in the two study catchments.
|
Page generated in 0.0726 seconds