The analysis reported here was done in the framework of two projects of the Global Vegetation Monitoring Unit (GVM, ex Monitoring of Tropical Vegetation [MTV] Unit) of the Space Applications Institute (SAI) of the Joint Research Centre (JRC):
the FIRE project (Fire in Global Resources and Environmental Monitoring) is dedicated to a permanent monitoring of vegetation fires at regional level, but all over the globe, and
the TREES project (Tropical Ecosystem Environment observation by Satellite) is dedicated to the development of an operational tropical forest monitoring system.
Both projects have to provide the services of the Commission with up-to-date, independent and policy-relevant information on three domains of strategic importance for the European Union:
the Framework Convention on Climate Change (Kyoto Protocol on source reduction and sink enhancement of green-house gases),
the implementation of projects which take into account sustainable development, and
the protection of forests of global importance.
In this context, a team of the GVM Unit was sent to Paramaribo (Suriname) in South America, from 8 to 21 March 1998, in order:
to map on real time the vegetation fires over Venezuela, Guyana, Suriname, French Guyana and Northern Brazil,
to assess the type of vegetation affected by the fires,
to format the information collected in order to support the evaluation of the role of these fires in the deforestation dynamics and of their impacts on the emission of green-house gases, and
to provide the scientific team of the LBA Project CLAIRE in Mainz (Germany) with in-situ real time information on the fire distribution.
The focus of the CLAIRE (Cooperative LBA Airborne Regional experiment; LBA = Large Scale Biosphere-Atmosphere Experiment) project is to provide the basis of knowledge required to determine the net exchanges of important gases and aerosols between the atmosphere and the Amazon region, and to understand the processes regulating these exchanges.
Data collection and processing in South America during the campaign of March 1998
From 9 to 20 March 1998, a total of 36 NOAA-AVHRR-HRPT images (1 km resolution) have been acquired and processed on an area of 2000 km x 2000 km covering Colombia, Venezuela, Guyana, Suriname, French Guyana, Northern Brazil and Northeastern Peru.
The acquisition of the NOAA-AVHRR-HRPT images has been done in-situ, three times a day, with a PC-based portable satellite receiver and a horn antenna. The pre-processing, radiometric calibration and geometric correction were carried out using the PANAIS software package developed by GVM (Janodet et al. 1996). The processing for vegetation fire location and GIS analysis were done using ERDAS IMAGINE 8.3 and ArcView packages, on Unix workstation.
Results were made available by e-mail within 24 hours of the satellite overpass, to the CLAIRE/LBA scientific team in Mainz (Germany) and to the services of the Commission, i.e. the DG JRC in Brussels (Belgium) and the direction of the SAI in Ispra (Italy).
General considerations on fire distribution in the region during March 1998
The intense cloud coverage over the region of interest during most of the observation period did not always allow the detection of all individual fires. Therefore, regional sets or groups of fires have been defined and located. Further investigation on individual fires has been conducted locally on specific areas of interest such as conservation areas and “indigenous areas”.
The regional groups of fires have been divided into the following categories:
a fire set is a group of individual fire events observed in a given area of a limited extent and clearly separated from the surrounding, located by the lat/long coordinates of its centre.
a fire front is a group of individual fire events distributed within an elongated cluster, positioned by the lat-long coordinates of its extremities.
a fire zone is a group of individual fire events distributed over large area, still clearly separated from the surrounding, and defined by the lat/long coordinates of its corners.
The various groups of fires have been mapped and analyzed in combination with relevant information such as administrative boundaries, river networks, vegetation cover types (D’Souza et al. 1995) and protected areas.
The satellite observations done from 9 to 20 March 1998 have lead to the definition of four main regions affected by fire activity in South America North of the Equator, called Fire Regions (Fig.1).
These four Fire Regions have been characterized in terms of:
the spatio-temporal distribution of fire and the type of vegetation affected,
the probable environmental impacts, relevant for the three European Union’s key issues.
These environmental impacts include:
the emission of greenhouse gases and aerosols leading to the degradation of air quality with possible health problems, and to the increase of CO2 emissions with consequences on climate change,
specific disturbances of the ecosystems, the vegetation cover and the soil, of their function and dynamics, leading to the degradation or even destruction of the natural resources like in the case of soil erosion.
Fire Region I: The Northeastern slopes of the Andes (Venezuela and Colombia)
The activity of the fires, which was previously limited in the Llanos, extended on the 12th and the 13th of March over the slopes of the Cordillera de Merida (Venezuela) and the northern part of the Cordillera Oriental (Colombia). These fires were distributed on a SW-NE transect some 200 km long and created smokes covering about 60,000 km2.
This fire event affected a mixture of “sub-montane forest” and “lowland dense forest”. Even if limited in space, it must be considered as having a very high environmental impact with important socio-economic consequences. The sub-montane forest ecosystem is indeed poorly adapted to fire and its disturbance exposes the soil to increased erosion on the slopes.
Fig.1. The four main fire regions in South America (North of the Equator) as derived from satellite observations between 9 and 20 March 1998.
Fire Region II: The Llanos of the Orinoco (Venezuela and Colombia)
Spread over most of the Llanos, the fires in this second region affected more especially two sub-regions: along the Meta river (Colombia) and over the Apure and the Arauca river basins (Venezuela).
At the beginning of the observed period, fires were limited to the central part of the Llanos (Venezuela and Colombia), over most of the Apure and Arauca river basins. A progressive movement of the fire activity was then observed toward East, following the Orinoco river until the end of the reporting period, on 18 March, when the fires were mainly concentrated between Ciudad Bolivar and Ciudad Guyana. The fire activity was intense during the whole period of observation, but with a peak on 13 March.
The main vegetation type affected by the fires in this region was a mosaic of “savannah woodland and xeromorphic forest”, with patches of “lowland dense moist forest”. Here again the forest ecosystem affected by the fires is far from being adapted to the burning practices and the soil degradation and erosion can be enhanced in region such as south of the Orinoco river.
Fire Region III: The coastal zones (Venezuela, Guyana, and Suriname)
The third region corresponds to the coastal zone of the Atlantic Ocean, where the fires were distributed according to three sub-regional patterns:
on the relief along the coast of the Caribbean Sea (Venezuela): the fires were observed mainly within the “dense moist forest” and some of them in the “agricultural mosaic”;
within the Orinoco delta: the fires showed a peak of activity on the 13th and 14th of March, affecting essentially the “coastal swamp forest”, and “low land dense moist forest” at the edges of the delta.
within the 50 km wide belt, parallel to the coast of Suriname and Guyana, liable to flooding from important rivers such as the Essequibo, Berbice or Nickerie: fire activities were particularly dense around Marlborough, Georgetown, New Amsterdam (Guyana), along the Courantyne river and Wageningen (Suriname). A peak of activity was observed from the 15 to 18 March. The vegetation types mostly affected in Guyana were the “lowland dense moist forest” and the “savannah woodland”. But in Suriname, the mixed class “coastal swamp forest and mangroves” was affected.
Due to the very high fragility of most of the coastal ecosystems affected here, one can expect very high environmental impacts of this third fire event. This includes the disturbance of the coastal geomorphologic equilibrium and increased erosion, with consequences on the terrestrial resources but also on the fishery capacities of the coastal zone.
Fire Region IV: The Roraima State (Brazil) and the Kanuku Mountains region (Guyana)
This fourth fire region covers most of the Rio Branco basin, upstream of the confluence with the Catrimani river (Brazil), and the upper basin of the Repununi and the Essequibo rivers (Guyana).
Fires were initially detected within the mosaic of “savannah woodland, xeromorphic forest” and “shrublands”. But after 11 March they clearly extended within the “lowland dense moist forest” in Guyana, with a peak of activity on 14 and 15 March. They also penetrated the “fragmented forest” and “dense moist forest” in Brazil after 12 March, with a peak of activity between 15 and 18 March.
Even when they were not in the non-forested domain, the fires were not positioned randomly. They were detected right at the edge of the forested types of vegetation, indicating clearly the purpose of this burning activity.
This fourth fire event has very strong environmental as well as social impact. Further investigations have to be conducted to assess and quantify in which way it affected, directly by burning fronts, or indirectly by dense smokes coverage, many indigenous areas as well as forest reserves and biological reserves.
Conclusions and Perspectives
From the present analysis of the fire patterns in this South American region during March 1998, and the comparison conducted with historical data from the fire season of 1992-93 (Dwyer et al. 1998; Stroppiana et al. 1998), one can make the following remarks.
The fire event was not totally exceptional and unpredictable. Reasons for burning are known and not new. But the intensity and extension of the fires in the dense moist forest domain (Brazil, Guyana) was effectively unusual. All the fires occurring in the region, and not only the ones affecting the forest, have strong environmental impacts and socio-economical consequences, especially because they affect vegetation on slopes exposed to soil erosion or very fragile coastal ecosystems.
Both of these first aspects were moreover minimized by the media, which focussed on the fires in the forested area of the Roraima State in Brazil.
The evaluation of the ecological and socio-economical consequences of the burning activity in this region requires an almost permanent flow of information on the location and timing of fires, at a scale that fits with the one of the phenomenon. This information must be first collected and then made available in a suitable format to the services of the Commission.
Earth Observation Systems provide here the only practical solution for such information collection. In this context the GVM unit of the SAI is currently developing the World-Fire-Web Network (Pinnock et al. 1998), a system for globally mapping fires in vegetation: a worldwide network of receiving stations will collect and process NOAA-AVHRR images for regional detection of fires. Daily global fire maps will be built up by automatically sharing regional maps over the Internet. This global fire information will then be available on-line and in near real-time. After a 12 months test period of a pilot network with partial global coverage (June 1998), the network will be progressively enlarged to give full global coverage.
As far as the information flow to the services of the Commission is concerned, the Tropical Forest Information System (Wood and Janvier 1995) is a good starting point. It is designed to be a tool for organizing and archiving information related to fire, vegetation and all topographic, geographic, and non-spatial information. It brings together the relevant datasets and allows performing the assessment and analysis of the impacts of fires on the environment. Finally it provide a tool for query, browsing and visualization of the fire products and results.
A prototype version has been installed by the TREES project at DG XI/D4. It is planned to install two others entries to the system in DG VIII and DGI/B.
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Dwyer N., J.-M.Grégoire, and J.-P.Malingreau. 1998. A global analysis of vegetation fires: spatial and temporal dynamics. Ambio 27 (3), 175-181.
Janodet E., A.Tournier, S.Brownlee, B.Glénat, and J.-M.Grégoire. 1996. Software package developed and implemented by MTV for the pre-processing and processing of NOAA-AVHRR images acquired with a portable receiving station. JRC Technical Note No. I.96.245, 32. Publ. European Commission, Joint Research Centre, Ispra, Italy, December 1996.
Stoppiana D., S.Pinnock, and J.-M.Grégoire. 1998. The Global Fire Product. Int. J. Remote Sensing (submitted 1998).
Wood R., and P.Janvier. 1995. Tropical Forest Information System: past and future priorities. Proceedings of Eurocarto XIII, Workshop on Scale and Extent, 35-49. Publ. European Commission, EUR 16406 EN, Luxembourg.
From: J.-M. Grégoire, B. Glénat, P. Janvier, E. Janodet, A. Tournier and J.M.N. Silva Address: Global Vegetation Monitoring Unit Space Applications Institute Joint Research Centre I – 21020 Ispra, Varese ITALY Department of Forestry Technical University Lisbon PORTUGAL