1.2. Concepts 

Deforestation is the complete removal of native vegetation in a given area.

The removal or felling of isolated trees or a few trees in a native vegetation plot, where the rest of the vegetation remains standing, does not constitute deforestation. Therefore, selective logging, forest management, and undergrowth fires that may result in vegetation thinning or other native vegetation degradation processes are not included in deforestation alerts. 

The definition of deforestation covers a series of particularities that are clarified below.

• Deforestation or Suppression of native vegetation - deforestation is commonly associated with the complete removal of forest vegetation. In MapBiomas Alerta, the term deforestation refers to the broader understanding, including any and all removal of native vegetation, also encompassing the removal of non-forest vegetation, such as fields and savannas.

• Primary or Secondary Deforestation - primary deforestation refers to the deforestation of primary forest or native vegetation, and secondary deforestation refers to the removal of secondary vegetation (an area previously deforested and undergoing vegetation regeneration). 

MapBiomas Alerta mainly addresses primary deforestation, as the alert systems used focus on primary vegetation areas. However, secondary deforestation areas, when verified, are also included in MapBiomas Alerta data.

• Gross and Net Deforestation - gross deforestation considers only the loss of native vegetation cover. Net deforestation or net loss refers to deforestation minus the area where vegetation regeneration has occurred.

• Deforestation Alert and Deforested Area - a deforestation alert refers to an event or indication of deforestation at a given location. The deforested area is the area effectively affected by the removal of native vegetation. MapBiomas Alerta identifies and refines deforested areas, using deforestation alerts from available monitoring systems such as DETER, SADs, and GLAD as a starting point.

• Deforestation Detection and Occurrence Date - the detection date refers to when deforestation was detected and/or verified by the original detection systems. The occurrence refers to the period when deforestation occurred (always a date prior to detection). 

• Observed Deforestation Area and Deforestation Rate  - the observed area is the spatial extent quantified directly by comparing satellite images from different dates (before and after deforestation). The official PRODES deforestation rate uses information from the observed area to estimate the deforestation that occurred throughout the territory, including areas that could not be observed. MapBiomas Alerta only works with the concept of observed area.

• Deforestation Speed - refers to the ratio between the total deforested area and the number of days elapsed between the beginning and end of deforestation, usually expressed in hectares or km2 per day. In MapBiomas Alerta, the speed is underestimated because the calculation is approximate, based on the dates of the satellite images selected and available to best document the moment before and after the deforestation episode.

• Deforestation and Degradation - deforestation deals with the complete removal of native vegetation, while degradation deals with the partial removal of native vegetation areas.