This month (January 2014), the Forestry Institute of São Paulo State (IF) is expected to begin production of its Inventário forestal da vegetação natural do estado de São Paulo (Forestry Inventory of Native Vegetation in the state of São Paulo), which identifies the boundaries of areas of native vegetation or reforestation in São Paulo State. Instead of using satellite images, as was done for the earlier versions, the Florestal team will use aerial photographs made available by Empresa Paulista de Planejamento Metropolitano (Emplasa), thereby increasing the spatial resolution 100 times over in comparison with the third edition, completed in 2009.
The improvement in spatial resolution is expected to expand the known dimensions of the area of native vegetation—Atlantic Forest, the Cerrado (savannahs), and mangrove thickets—in the state of São Paulo. In the third version of the inventory, the use of satellite images with a resolution four times greater than that of the previous edition brought into view some previously unnoticed areas, and increased the area occupied by fields and forests in various stages of conservation by 25%. This area now measures 4.34 million hectares, the equivalent of 17.5% of the state’s territory. Other states, such as Rio de Janeiro and Minas Gerais, have conducted similar studies, although not with such a detailed scale. (see Pesquisa FAPESP Issue No. 170).
“It was State Secretary of Environment Bruno Covas who personally asked in May 2013 that we prepare an updated version of the inventory,” says Marco Aurélio Nalon, an IF researcher and coordinator of the effort. The Inventário Florestal has become a vital document in defining official guidelines that may contribute to environmental policy and for studies of biodiversity in this state. The second edition, released in 2003 with support from the Biota-FAPESP Program, led to passage of a law that protects what native vegetation remains in the state of São Paulo.
One Map Every Two Months
The planning for the fourth edition, budgeted at R$2 million, calls for production of one simplified map every other month, sequenced by hydrographic basin, to help supervisory groups such as the Environmental Police and the Department of Natural Resource Protection in their field work. Another new feature is that production of the maps will, for the first time, be contracted out. The contractor company is expected to be chosen in early January via electronic bidding and will immediately begin producing maps, under supervision by the institute’s team.
“The images we will use are already here,” says Nalon, pointing to one of three hard disks lying on his desk among three computer monitors. On the walls are the photos of mountains in the United States that he has scaled during his years as a mountain-climber, starting in 1985. “There are 1,292 aerial orthophotographs of the state of São Paulo, produced on a scale of 1:25,000, with a spatial resolution of one meter.” He notes that in the two earlier versions of the inventory, the smallest area analyzed measured from two to three hectares, equivalent to two or three soccer fields. In 2010, for the third edition, the minimum area shrank to 2,500 square meters (m2), one-fourth of a soccer field, and showed many more details. Now, according to Nalon, with the current batch of aerial photos the minimum area will be smaller—about 900 to 1,000 m2 or one–tenth of a soccer field. “This is the stuff of dreams,” he says, with great satisfaction.
The increase in resolution and the new organizational model that will permit continuous production of maps during the course of one year, represent an enormous advance over the first edition of the Inventário Florestal that came out in 1993. The first map, produced from images from the Landsat satellite after two years of manual labor, is 4 meters wide by 3 meters tall, and is on display at one of the offices of the Institute’s Geoprocessing Laboratory.
“We pasted 416 topographical maps from the IBGE on the wall, made some corrections, photographed them, and reduced them to a scale of 1:250,000,” Nalon recalls. “When someone around here starts complaining about life, I ask: “ Do you want to paint?” And I make him look at the map. Today the images have all been scanned and interpretation is semi-automatic, but I’ve certainly painted a lot of maps in my lifetime, like this one, with a hydrographic pen.” Seen from close up, it is obvious that the map was produced informally: the areas of vegetation—Atlantic Forest, mangroves, and savannahs—and areas reforested with pines and eucalyptus were hand-painted in different colors. The urban areas were left blank and tiny typed labels were used to designate the conservation units.
Nalon, a physicist by training, was assigned the task of modernizing the map production of native vegetation in the state of São Paulo in 1991, using computer graphics and image interpretation programs. Under the previous method, which was completely manual, it was hard to see whether a given area of vegetation had grown or shrunk from one year to the next. “We placed the satellite image on a light table, and then laid a transparent sheet over it and used India ink to draw in the fragments of native vegetation. We drew the contour lines by hand, and used an apparatus to calculate the area occupied by each fragment,” he recalls. “ We made index cards for the fragments, each one was numbered, and we digitized them on a computer spreadsheet.”
KRONKA, F.J. N. et al. Inventário florestal do estado de São Paulo. IF. 1993.
KRONKA, F.J. N. et al. Areas de domínio do cerrado no estado de São Paulo. IF. 1998.
KRONKA, F.J. N. et al. Inventário florestal das áreas reflorestadas do estado de São Paulo. IF. 2002.
KRONKA, F.J. N. et al. Inventário florestal da vegetação natural do estado de São Paulo. IF. 2005.
KRONKA, F.J. N. et al. Inventário florestal da vegetação natural do estado de São Paulo: Regiões Administrativas de São José dos Campos (Litoral), Baixada Santista e Registro. IF. 2007.