941 resultados para Timber Plantations
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Sao Paulo is the most developed state in Brazil and little of its native vegetation remains. In Luiz Antonio and Santa Rita do Passa Quatro municipalities, only small fragments of cerrado (Brazilian savanna) physiognomies (cerrado, cerrado sensu stricto) and of semideciduous forest have been left, surrounded by eucalyptus silviculture and sugar-cane agriculture. However, that vegetation mosaic still shelters large mammals, including several carnivore species. To detect the carnivores present in such a mosaic area (50,000 ha), and to find out how they use the landscape, we recorded them through 21 camera traps and 21 track plots, during 18 months. Species richness, diversity and relative frequency were evaluated according to the habitat. Ten species were recorded, some of them locally threatened to extinction (Puma concolor, Leopardus pardalis, Chrysocyon brachyurus). Species diversity did not significantly differ among fragments, and although most species preferred one or another habitat, the carnivore community as a whole explored all the study area regardless of the vegetation cover;eucalyptus plantations were as used by the carnivores as the native fragments. Therefore, it seems possible to maintain such animals in agricultural landscapes, where some large native fragments are left and the matrix is permeable to native fauna.
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The Rufous-thighed, Hawk (Accipiter erythronemius) is a poorly-known, small raptor that dwells in forests and wooded savannas in south and eastern Brazil, Taraguay, eastern Bolivia, north and central Argentina, and Uruguay. We studied breeding biology and food habits of the Rufous-thighed Hawk from 1994 to 2007. We documented 14 breeding attempts recorded at nine nest sites in eight localities in Argentina and Brazil. Rufous-thighed Hawks were year-round residents at the study areas. The breeding season was c. 38 weeks long (June through March). Territorial behavior and courtship spanned for 22 weeks starting in mid June. Nest-building started in August. Nestlings were observed throughout December and into early January while fledglings were observed from late December through late March. Most nest sites were conifer plantations averaging 32.2 (SD = 10) years old, 12.6 ha (SD = 11.3) in size with trees averaging d 37.5 cm (SD = 13.5) of diameter at breast height. Nests were placed 20.2 m high (SD = 5.7), near the trunks of non-emergent conifers (Pinus sp. or Araucaria angustifolia). Nests were made of sticks, greater diameter averaging 48.8 cm (SD = 11.4), while nest depth averaged 23.3 cm (SD = 14). Prey items were birds (n = 49) ranging in size from c. 10 g [House Wren (Troglodytes, aedon)] to c. 140 g [White-tipped Dove (Leptotila verreauxi)]. Young started to chase birds at the age of 42-45 days in mid January. Adult males were primarily food providers but also aided in nest defense against other raptors. Females incubated, brooded, and fed young, and took leading roles in defense against humans. Rufous-thighed Hawks had unlined nests placed high in trees, and breeding season was markedly protracted.
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A recent debate has contrasted two conservation strategies in agricultural landscapes; either ""land sparing`` farm development combining intensive production practices with forest set-asides, or ""wildlife-friendly`` farming with greater on-farm habitat value but lower yields. We argue that in established mosaic landscapes including old cacao production regions where natural forest has already been reduced to relatively small fragments, a combination of both strategies is needed to conserve biodiversity. After reviewing the evidence for the insufficiency of either strategy alone if applied to such landscapes, the paper focuses on the cacao production landscape of southern Bahia, Brazil, once the world`s second largest cacao producer. Here, small remaining areas of Atlantic Forest are embedded in a matrix dominated by traditional cacao agroforests, resulting in a landscape mosaic that has proven favorable to the conservation of the region`s high biodiversity. We show that current land use dynamics and public policies pose threats but also offer opportunities to conservation and describe a three- pronged landscape conservation strategy, consisting of (i) expansion of the protected areas system, (ii) promotion of productive yet biodiversity-friendly cacao farming practices, and (iii) assistance to land users to implement legally mandated on-farm reserves and voluntary private reserves. We discuss recent experiences concerning the implementation of this strategy, discuss likely future scenarios, and reflect on the applicability of the Bahian experience to biodiversity rich cacao production regions elsewhere in the tropics.
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In this paper we study the Lyapunov stability and Hopf bifurcation in a biological system which models the biological control of parasites of orange plantations. (c) 2007 Elsevier Ltd. All rights reserved.
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During sugar cane harvesting season, which occurs from May to November of each year, the crops are burnt, cut, and transported to the mills. There are reports showing that mutagenic activity and PAH content increase during harvesting season in some areas of Sao Paulo State in comparison with nonharvesting periods. The objective of this work was to preliminarily characterize the mutagenic activity of the total organic extracts as well as corresponding organic fractions of airborne particulate matter (PM) collected twice from two cities, Araraquara (ARQ) and Piracicaba (PRB), during sugar cane harvesting season using the Salmonella/microsome microssuspension assay. One sample collected in Sao Paulo metropolitan area was also included. The mutagenicity of the total extracts ranged from 55 to 320 revertants per cubic meter without the addition of S9 and from not detected to 57 revertants per cubic meter in the presence of S9 in areas with sugar cane plantations. Of the three fractions analyzed, the most polar ones (nitro and oxy) were the most potent. A comparison of the response of TA98 with YG1041 and the increased potencies without S9 indicated that nitro compounds are causing the observed effect. More studies are necessary to verify the sources of the mutagenic activity such as burning of vegetal biomass and combustion of heavy duty vehicles used to transport the sugar cane to the mills. The Salmonella/microsome assay can be an important tool to monitor the atmosphere for mutagenicity during sugar cane harvesting season.
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Leaf fibers are fibers that run lengthwise through the leaves of most monocotyledonous plants such as pineapple, banana, etc. Pineapple (Ananas comosus) and Banana (Musa indica) are emerging fiber having a very large potential to be used for composite materials. Over 150,000 ha of pineapple and over 100,000 ha of banana plantations are available in Brazil for the fruit production and enormous amount of agricultural waste is produced. This residual waste represents one of the single largest sources of cellulose fibers available at almost no cost. The potential consumers for this fiber are pulp and paper, chemical feedstock, textiles and composites for the automotive, furniture and civil construction industry.
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Bergkvist insjön AB is a sawmill yard which is capable of producing 350,000 cubic meter of timber every year this requires lot of internal resources. Sawmill operations can be classified as unloading, sorting, storage and production of timber. In the company we have trucks arriving at random they have to be unloaded and sent back at the earliest to avoid queuing up of trucks creating a problem for truck owners. The sawmill yard has to operate with two log stackers that does several tasks including transporting the logs from trucks to measurement station where the logs will be sorted into classes and dropped into pockets from pockets to the sorted timber yard where they are stored and finally from there to sawmill for final processing. The main issue that needs to be answered here is the lining up trucks that are waiting to be unload, creating a problem for both sawmill as well as the truck owners and given huge production volume, it is certain that handling of resources is top priority. A key challenge in handling of resources would be unloading of trucks and finding a way to optimize internal resources.To address this problem i have experimented on different ways of using internal resources, i have designed different cases, in case 1 we have both the log stackers working on sawmill and measurement station. The main objective of having this case is to make sawmill and measurement station to work all the time. Then in case 2, i have divided the work between both the log stackers, one log stacker will be working on sawmill and pocket_control and second log stacker will be working on measurement station and truck. Then in case 3 we have only one log stacker working on all the agents, this case was designed to reduce cost of production, as the experiment cannot be done in real-time due to operational cost, for this purpose simulation is used, preliminary investigation into simulation results suggested that case 2 is the best option has it reduced waiting time of trucks considerably when compared with other cases and it showed 50% increase in optimizing internal resources.
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For the author, the concept of testimonial rhetoric means the discursive strategy with which the narrator attempts to make understood that narration is not a product of fiction, but the product of a social reality which he witnessed and lived. The First World War brought with it an increase in the demand for rubber which entailed an attitude on thepart of the consumer countries as well as of the producers, of silencing and refusing to recognize the infrahuman conditions to which thousands of people who worked on the rubber plantations were submitted. This is the social reality, the context in which José Eustasio Rivera wrote La Vorágine.
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Variation i björkvirkets färg beror på art, läge i träd, ursprung och lagringstid. Vårtbjörk har en mörkare färg än glasbjörk, men livligare struktur och glans. Timmer hugget under tillväxtsäsongen bör sågas färskt eller lagras högst en månad. Vid brädgårdstorkning är god luftcirkulation och skydd för väta och direkt solljus väsentligt. Strövirkets färskhet är av stor betydelse för att undvika fuktfärgning av virket.Variation in birch colours depend on species, position in tree, origin and the storage period. White birch is darker than hairy birch but with a lively structure and shine. During vegetation period timber storage exceeding one month should be avoided. Air circulation, protection from rain and direct sunlight are essential for yard drying. Freshness of stickers used for stacking is important to avoid water marks on wood surface.
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Variation in wood properties for Picea abies trees and logs of different dimensions has been studied at two sites in southern Sweden of different site quality class. Trees have been classified as dominant or sub-dominant, according to their height. Log and board grades were classified and strength grade of boards, basic density and annual ring width measured. A similar study made on four northern sites was used as reference material.Sub-dominant trees were of superior quality in comparison to dominant trees, when classified by log and board grades or strength grading. Differences were accentuated for the second log where the sub-dominant trees had superior strength and low amount of boards with coarse branches. The results correspond well to those from the northern region, Jämtland. The classifica¬tion of boards as well as bending strength indicated superior properties on timber from northern sites even though the basic density was similar.
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SammanfattningHögskolan Dalarna har i samarbete med Skogsägarna Mellanskog, Naturbränsle i Mellan¬sverige AB och GDE-Net genomfört studier på en ny metod för uttag av skogsbränsle från slutavverkningar. Metoden går ut på att timmer tas ut som enda rundvirkessortiment. Resten av trädet, samt klenare träd som inte håller timmerdimension, tas ut som ett bränslesortiment. Metoden har jämförts med en konventionell slutavverkning med uttag av timmer, massaved och GROT-flis.Enligt genomförda försök skulle en avverkning enligt den nya metoden (långa toppar) ge ett högre drivningsnetto och drygt dubbelt så mycket bränsleflis som en konventionell avverk¬ning. En anledning till det högre drivningsnettot är att kostnaden för flisning blir lägre än vid flisning av GROT och att flisen betalas bättre än GROT-flis. Resultaten är beroende av de faktiska beståndsförutsättningarna och gällande prisrelationer mellan massaved och bränsle¬flis.Faktorer som har en positiv inverkan på drivningsnettot vid uttag av ”långa toppar” är t.ex. stora uttagsvolymer och korta terrängtransportavstånd samt bestånd med en hög andel virke av låg kvalitet eller udda sortiment som betalas dåligt på rundvirkesmarknaden.SummaryIn Sweden forest energy from final felling is traditionally harvested as logging residues after harvesting of timber (saw logs) and pulpwood, but depending on the market situation other methods with higher yield of forest energy might be of interest. Dalarna University has study a new method called “Undelimbed long tops” where only saw timber was taken out as an industrial assortment. The rest of the trees and smaller trees that don’t hold timber dimensions was left intact on the clear-felled area and been chipped later on. The study was done in different stands with some different conditions. The results have been compared with the traditional method for final felling. The surplus (forest owners net income) was higher in almost all stands when the method with “undelimbed long tops” was used, compared to the traditional method for taking out forest energy, and the volume of chips was more than doubled. A reason for the higher income from long tops is that the costs for chipping is lower and the prize of chips is higher compared to chips from logging residues. Other reason is that forest owners will not be paid for wasted pulpwood, but will be fully paid for the chips from such pulpwood. Factors that will have a positive influence on the ULT-method are for example large logging volumes and short distance between the logging area and the landing, different kinds of price reductions on pulpwood and large volumes of rotten wood or low paid industrial assortments.
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Inom ramen för projektet Energi- och miljökompetenscentrum vid Högskolan Dalarna haren kortare förstudie kring tekniken som används av Timber Tower GmbH för högavindkrafttorn i trä gjorts. Huvudsyftet med studien har varit att titta närmare på teknikenoch dess potential för svensk landbaserad vindkraft samt utreda vad detta kan innebära förregionen.Trenden för landbaserad vindkraft i skogsmiljö går mot allt högre torn. Skogsmiljön gör attden marknära turbulensen och vindgradienten blir större än över t.ex. hav vilket gör detmer föredelaktigt att använda högre torn.Tekniken som Timber Tower GmbH använder är att bygga tornet på plats med en koniskhålstomme av plana paneler av korslimmat limträ (som annars främst används vidbyggnation av höga hus med massivträstomme). Tekniken är skyddad av ett flertalpatentansökningar varav minst en är beviljad.Vid en jämförelse mellan trätorn och svetsade ståltorn (som är den dominerandetorntekniken idag) kan det konstateras att trätornstekniken är ekonomiskt intressant.Framförallt blir trätornen mer intressanta i jämförelse med ståltornen vi ökande höjder (>100 m) pga. dess transportfördelar. Vidare bör det nämnas att de torntekniker somanvänds idag vid höjder runt 140 m och högre främst är fackverkstorn i stål ochhybridtorn med en hög bas av förspänd betong och övre delen i stål.Då ett typgodkännande av ett vindkraftverk gäller torn och turbin är det i praktiken alltidturbintillverkaren som prissätter och levererar ett komplett vindkraftverk. Medutgångspunkt i regeringens planeringsram för svensk vindkraftutbyggnad (20 TWh/årlandbaserad vindkraft 2020) kan dock marknadsvärdet för torn uppskattas till 2-3 miljarderkr/år fram till 2020. För trätorn motsvarar detta en årlig potentiell volym på ca 190 000 m3.Slutsatsen i denna korta studie är att det är tekniskt möjligt att designa ett trätorn i rimligadimensioner för en 2-3 MW turbin med navhöjd ca 140 m och att detta sannolikt även ärekonomiskt intressant. Då ett trätorn blir något lättare än motsvarande ståltorn går det åtmindre energi för att göra ett trätorn. Hur mycket mindre är dock osäkert pga. den storaspridningen i siffror för energiåtgång för stålproduktion och i praktiken blir skillnadenäven leverantörsberoende. Eftersom andelen förnyelsebar energi är betydligt större vidtillverkningen av materialet för trätornen kommer trätornet att ge en betydande sänkningpå utsläppt CO2e/kWhel jämfört med motsvarande verk med ståltorn. Ett annat argumentför trätorn är förenklade transporter jämfört med t.ex. svetsade ståltorn eller hybridtornmed prefabricerade betongelement.Om tekniken etableras kan det i förlängningen leda till en regional påverkan i form av ökatlokalt innehåll i vindkraftprojekten t.ex. genom ökade råvaruleveranser (eg. sågat ochtorkat virke), lokal produktion av korslimmat limträ eller exempelvis bildande avspecialiserade montagefirmor. Det största hindret för tekniken just nu är dessmarknadsintroduktion och acceptans samt typgodkännande tillsammans med en för svenskmarknad intressant turbinleverantör. För att få acceptans för tekniken krävs byggande ochutvärdering av minst ett verk med trätorn. En intressant storlek för marknaden är en 2-3MW turbin med navhöjd ca 140 m. Ett sådant verk skulle i så fall få det högstavindkrafttornet i Sverige och sannolikt det högsta vindkrafttornet i trä i världen. Byggandetav ett första verk med trätorn skulle sannolikt även kräva ett behov av stödfinansiering föratt täcka en projektörs ökade risk. Då flera vindkraftetableringar i regionen uppvisar godaproduktionsresultat (med Tavelberget som gott exempel) visar det att regionen ärintressant för introduktion och utvärdering av ny teknologi.
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Increasing costs and competitive business strategies are pushing sawmill enterprises to make an effort for optimization of their process management. Organizational decisions mainly concentrate on performance and reduction of operational costs in order to maintain profit margins. Although many efforts have been made, effective utilization of resources, optimal planning and maximum productivity in sawmill are still challenging to sawmill industries. Many researchers proposed the simulation models in combination with optimization techniques to address problems of integrated logistics optimization. The combination of simulation and optimization technique identifies the optimal strategy by simulating all complex behaviours of the system under consideration including objectives and constraints. During the past decade, an enormous number of studies were conducted to simulate operational inefficiencies in order to find optimal solutions. This paper gives a review on recent developments and challenges associated with simulation and optimization techniques. It was believed that the review would provide a perfect ground to the authors in pursuing further work in optimizing sawmill yard operations.
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This paper reports the findings of using multi-agent based simulation model to evaluate the sawmill yard operations within a large privately owned sawmill in Sweden, Bergkvist Insjön AB in the current case. Conventional working routines within sawmill yard threaten the overall efficiency and thereby limit the profit margin of sawmill. Deploying dynamic work routines within the sawmill yard is not readily feasible in real time, so discrete event simulation model has been investigated to be able to report optimal work order depending on the situations. Preliminary investigations indicate that the results achieved by simulation model are promising. It is expected that the results achieved in the current case will support Bergkvist-Insjön AB in making optimal decisions by deploying efficient work order in sawmill yard.
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Bin planning (arrangements) is a key factor in the timber industry. Improper planning of the storage bins may lead to inefficient transportation of resources, which threaten the overall efficiency and thereby limit the profit margins of sawmills. To address this challenge, a simulation model has been developed. However, as numerous alternatives are available for arranging bins, simulating all possibilities will take an enormous amount of time and it is computationally infeasible. A discrete-event simulation model incorporating meta-heuristic algorithms has therefore been investigated in this study. Preliminary investigations indicate that the results achieved by GA based simulation model are promising and better than the other meta-heuristic algorithm. Further, a sensitivity analysis has been done on the GA based optimal arrangement which contributes to gaining insights and knowledge about the real system that ultimately leads to improved and enhanced efficiency in sawmill yards. It is expected that the results achieved in the work will support timber industries in making optimal decisions with respect to arrangement of storage bins in a sawmill yard.