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Topografia Geral Pdf

ruthenpress.info - Free download as PDF File .pdf) or read online for free. José Machado Coelho Júnior - Topografia ruthenpress.info uploaded by. uploader avatar. cartografia e topografia geral - - a topografia (do grego topos = lugar, local e grafo = descrição) significa a descrição minuciosa de uma. 23 fev. Main Survey Instruments used in environmental monitoring: A classic approach of the book Topografia Geral. Article · May with 4,

Natural lightning fires can easily happen in savannas and grasslands, but they are rare in the moist rainforests. Today, anthropogenic fires are frequent in both the fire-adapted cerrado Brazilian savanna and the fire-sensitive rainforest. In this paper, I compare two very different biomes concerning their susceptibilities and responses to fire: the site rainforest and the cerrado. I present an overview of their fire history, especially regarding human-made fires for land management, and pull together information about the use of fire by indigenous peoples in the cerrado and the site, as this information is very fragmented. Accordingly, I describe how fire regimes have changed in these biomes over time due to agricultural practices and the consequences of the current altered fire regimes. After European settlement, fire frequency greatly increased in the cerrado, especially related to cattle ranching, and more recently in the more seasonal landscapes in the site. In cerrado natural preserves, however, managers try to keep fire away, but wildfires eventually come and develop into destructive events.

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TOPOGRAFIA GERAL

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New York, The Macmillan Company, Clinical Reptile Gastroenterology.

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Ceres, , Smith, D. Gastrointestinal studies in the green iguana: technique and reference values. Links of the Group Contiene todo lo de altimetria, planimetria, However, there were some difficulties when linking GPS surveying to the Costa Rican vertical network. Leica Geosystems: When it has to be right ; Revolutionising the world of measurement and survey for nearly years, Leica The new manual total stations rely on a product concept that has been Confederaziun svizra.

Uffizi federal da topografia swisstopo. Federal Office Plan to connect a newly established datum to a land based levelling system if However, in periods of severe drought, parts of the site biome where there is some climatic seasonality—mainly where it borders the cerrado biome but also in core areas of the site forest—are able to catch fire, especially if the forest structure has been altered by human activities Figure 3.

In fact, it is believed that the real cause of wildfires in the site forest is the synergistic effect of droughts and human activities Cochrane et al. Photo by Mark A. Soil charcoal has been found in the site forest region and provides a good indication of fire occurrences. From the end of Pleistocene through the whole Holocene, at least two periods of forest retreat concomitant with the advance of savannas and grasslands might have occurred: between 11 yr to 10 yr, and between yr to yr BP Pessenda et al.

Pieces of paleocharcoal found in the region are dated to the last years when primitive human groups probably were already around Sanford et al.

It is believed that pre-Columbian humans retarded the advance of forests over savannas during the moister periods by frequently setting fire in the vegetation. By years BP, large-scale burning in the site region denoted intense human activity Fearnside By the time the Portuguese arrived in Brazil AD , the country was populated by more than a thousand different indigenous groups, estimated at 1 to 5 or even 10 million people FUNAI After the European colonization, the indigenous peoples were reduced to a tenth, mostly due to diseases contracted from Europeans Bush et al.

That extreme reduction in the indigenous populations most probably was the reason for a substantial decrease in fire activity after the European colonization up to the year , as evidenced by charcoal records Bush et al.

Specific studies on the use of fire by Brazilian indigenous groups are rare, and the existing information, mostly coming from anthropological studies, is fragmented. Nevertheless, the available information shows that Brazilian indigenous peoples used fire for a number of reasons: to clear pathways and the surroundings of their houses to facilitate walking; to open areas for cultivation; to kill or drive away pests and snakes; to eliminate wastes; to attract and drive game during hunting; to stimulate grass regrowth, flowering, and fruiting of some plants; to attract game that fed on fresh herb and fruits; and to collect honey.

They also used fire in their wars and rituals, for signaling, and for shifting cultivation slash-and-burn Gross et al.

None of the indigenous groups in Brazil were pastoralists; they were hunter-gatherers and land-managers who used fire as an important tool to manipulate the environment according to their needs. They used fire to create islands of resources orchard patches where they planted several species of fruit trees and other useful plants.

Fire was used to make firebreaks around these orchards to protect them from accidental burns. Specific fire regimes were applied to stimulate the flowering and fruiting of some species or to control plant diseases. Cool burns during the first spring rains were also made to fertilize the soil through the ashes deposited on soil surface, without damaging the plants.

Therefore, mosaic burnings in savannas were used to increase the diversity of useful plants and resources Posey , ; Anderson and Posey , ; Hecht Another use of fire was for shifting cultivation. The practice was adopted by most groups of indigenous peoples and seems to have appeared independently in several tropical ethnic groups Adams The task was careful and detailed: burns were usually made in small patches; they first opened gaps in the forest by cutting most trees, also calculating the way to fell them in order to leave open corridors where they planted edible roots and bulbs cassava, sweet potato, etc.

After a couple of months, when the felled trees were drier, they burned them, controlling the fire temperature so as to not damage the plantation. After that, the field was abandoned for some decades to recover fallow period.

With this kind of rather sophisticated agroforestry system, the indigenous peoples deliberately directed forest succession according to their needs. There is also evidence that indigenous groups from the site basin had been using fire since pre-Columbian times to create terra preta, a very dark, organic, and fertile soil with a high charcoal content Glaser et al.

To make this kind of substratum, they used a technique named slash-and-char in which, similar to slash-and-burn, forest patches were cleared but burned at relatively low temperatures to create charcoal Woods et al.

Whatever the reason, the use of fire by indigenous peoples was very careful and accurate. The objectives for burning, the burning site, and the fire behavior were well defined and determined the fire regime to be adopted.

Based on several ecological indicators such as river cycles, clouds, wind direction, level of rivers, cycles of key plant and animal species, the elders decided when and how to burn, and the leaders announced the decision to the male group, denoting a clear social control over the activity and a precise way to keep their resources Posey , ; Anderson and Posey ; Pivello Current Fires in the Cerrado and site Forest Natural fires in Brazil are caused by lightning; relevant volcanic activities in the country are virtually none.

In their four-year survey, every anthropogenic fire registered happened in the dry season and burned extensive areas, contrasting with the natural fires that burned small patches and were rapidly extinguished by rain. However, the great majority of wildfires both in the cerrado and in the site region are caused by human ignition.

Today people mainly use fire to remove the natural vegetation to install crop cultures or pastures; when performing the shifting cultivation; or to manage their agricultural crops, either to burn residues or to stimulate the regrowth of herbs to feed cattle in the dry season.

Accidental fires that turn out to be large wildfires are common due to these practices, and arson fires are not uncommon.

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The practice of shifting cultivation was transmitted by indigenous peoples to local peasants caboclos after European colonization. However, the knowledge was partially lost and fire management was no longer so careful and precise. In order to be sustainable, shifting cultivation demands low population densities and large areas to allow an adequate fallow period in a rotating system. But caboclos have a sedentary lifestyle, and their agricultural lands are restricted to relatively small areas.

Therefore, they burn large plots at each time in high frequency. Signs of soil degradation in these reserves can be observed Gross et al. The use of fire to replace native vegetation by agriculture is widespread both in the cerrado and the site.

The cycle usually starts with the removal and burning of the vegetation; part of the trees is transformed to charcoal, and the rest of the vegetation turns into ash and is used as soil fertilizer.

Estudos Geográficos Topografia Geral O Município de Itaberaba

The cleared area is then transformed into planted pasture, subsistence cultures, or industrialized grain crop plantations, mostly of soybean. In industrial agriculture, intense fires are initially used to clear vegetation; however, during the crop production cycle, fire is occasionally used to burn crop residues Ratter et al.

Cattle were introduced in the cerrado region during colonial times Barcellos et al. In the extensive beef-cattle production, annual or biennial fires are commonly applied to stimulate grass regrowth in the dry season when forage is in short supply. Most cattle ranchers do not make firebreaks and the fire spreads to large areas. About 40 years ago, beef-cattle production in the cerrado became large-scale and directed toward exportation.

On such ranches, the native vegetation is totally removed, highly productive African grasses are planted, and fire is occasionally used to manage specific problems. As in the cerrado, the production of beef cattle has been the main reason for burning the site rainforest. The Portuguese colonizers introduced cattle in the site in the seventeenth century, but large-scale production started in the s Perin et al. Although they were not able to separate fire types, this increase could have been due to cattle grazing.

Pastures are not sustainable in the site region, and when the soils are exhausted, cash-crop farmers download the land to introduce intensive agriculture, usually soybeans Ferreira et al. The conversion of the site forest into pastures or intensive agriculture is usually preceded by logging. Roads are opened into the forest to permit the entering of loggers, and the extraction and transportation of timber leads to the opening of more roads and trails.

Logging activity itself does not require fire; however, the extraction of large trees opens the forest canopy, decreases the local moisture, and highly increases the forest susceptibility to wildfires that come from pastures or slash-and-burned areas nearby Fearnside , Balch et al. Logged forests that are no longer profitable are usually replaced by pastures; and for that, the remaining forest is totally burned.

After installing the pasture, fire is periodically used to kill woody regrowth and to maintain some fertility in the soil for some years.

Consequences of Fire Altered Regimes and the Lack of a Fire Management Policy As in many places in the world, current land use and agricultural practices have considerably changed fire regimes in the cerrado and site regions compared to pre-Columbian times Figure 4 —a result of too much fire, too little fire, or the wrong fire regime Shlisky et al.

The wrong fire regime leads to soil degradation, biological invasions, and overall biodiversity loss. Human-caused fires in most cerrado fragments are happening at a much higher frequency than in the past, and the fires are hotter because people perform burns in the dry season, in contrast to wet-season natural fires Ramos-Neto and Pivello This new regime favors herbaceous species and encourages the maintenance of the open cerrado physiognomies, or it may cause land degradation Pivello and Coutinho , However, the opposite situation happens in cerrado conservation areas where fires are usually not allowed and there are no fire management programs based on prescribed burnings to maintain the savanna natural biological cycles.

As a result, fuel builds up, boosting the risk of wildfires, and when an accidental fire occurs, it is much more severe, burns large extents, and threatens the native fauna and cerrado endemic species Pivello and Norton , Pivello These return intervals may appear in other regions, but that has not yet been determined. Such short intervals may either convert the forest to a savanna Cochrane et al.

The combination of human activities and dry years increases considerably the number and extent of wildfires in both the site and cerrado regions. This is the case of the present year , when the number of fire spots detected by satellite images and registered by the Instituto Nacional de Pesquisas Espaciais INPE from January to August was about four times higher than in the same period of the previous year Figure 5. The values from onwards may be somewhat underestimated because NOAA was decommissioned that year.

In the cerrado biome, fires are also more abundant in the states of Mato Grosso, as well as in Tocantins, where most of the remaining large cerrado patches are located Figure 7. These frequent fire episodes demonstrate the lack of structure and planning related to accidental fires in the country, especially during dry years when wildfire incidence is much higher than usual.

These fires also highlight the need for a huge program of education and awareness directed toward the agriculturalists, and followed by effective inspection and application of penalties in cases of inappropriate fire usages. Wildfires caused by inappropriate agricultural practices are also the main sources of greenhouse gases emissions, because in Brazil, such emissions are mostly due to the burning of native vegetation.

Although today the cerrado deforestation rate is twice that of the site forest, both biomes make a similar contribution to carbon emissions, even though the site forest aboveground biomass is much higher. Barlow and Peres point out that biomass burning is one of the few parameters of climate change that can be directly controlled. Therefore, social and economic policies to stimulate small-scale agricultural projects where fire is not applied should be developed for the site region.

In the cerrado region, cattle ranching can be sustainable if appropriate fire regimes are followed and wildfire prevention measures are taken. Still, cerrado conservation areas would benefit from controlled management fires under proper regimes, as fire is part of cerrado evolution and maintains relevant ecological processes and the native biodiversity.

Concerning carbon emissions, studies demonstrate that when the native vegetation is not suppressed or replaced by crops, all the emissions of a burn will be re-assimilated after one year due to the rapid and vigorous regrowth of cerrado plants Santos et al.

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