Article Preview
TopIntroduction
Forests are among the most important natural resources for animal, plant, and human survival. They shelter most of the terrestrial biodiversity shared by several species of birds, mammals, and amphibians, powerful and crustaceans, etc. which, unfortunately, cannot live outside their natural habitat: the forest. According to the Food and Agriculture Organization (FAO)1, our planet has lost nearly 420 million hectares of forest cover since 1990; for the period between 2015 and 2020 alone deforestation is estimated at 10 million hectares. These alarming numbers show the extent of the damage that ravages all our planet's forests every year, mainly due to several factors (Ganteaume et al., 2013). At the top of the podium is the human factor and its various activities, industrial and commercial (high demand and consumption of wood), agricultural (a frantic search for new cultivable land) of urban design (increasing sprawl of cities) (A. Sharma et al., 2020). There are also other natural factors, such as climate change (Flannigan et al., 2006), droughts, and diseases. According to their unfolding process, all these factors that the authors of this paper have just mentioned spread out over a long period to show their devastating consequences on the forest, the authors of this paper qualify them as long factors. On the other hand, there are abbreviated factors that operate over a limited period but with equally devastating damage to the forest (Ganteaume et al., 2013). In the ranking of these short factors, forest fires (FF) occupy the first place.
Indeed, a FF can be triggered by the effect of winds to spread rapidly and thus devastate a larger forest cover, in such a short time. A FF can intensify to such a point that it becomes gigantic and uncontrollable, threatening all the fauna and flora of the region and even nearby dwellings (Boer et al., 2020). The causes of a forest fire are mainly classified into two distinct categories: natural and human. For the first category, wildfires occur as a result of a thunderstorm or a storm accompanied by lightning, which falls directly on the trees (Petrov et al. 2020). Therefore, the initial trigger of the fire is mainly in the heights (ITFH). While the FF is caused by humans; by negligence or criminal acts; the initial trigger of the fire is mainly on the ground (ITFG). Within this category of fires started on the ground the authors of this paper classify them into two distinct types. The first type is the fire on the surface (FS), which burns dead tree debris; this type of fire is easier to control and extinguish. On the other hand, the second type of fire is a fire deep in the ground (FDG), precisely in the bowels of the dead vegetation. This second type of fire is difficult to detect and extinguish because it remains buried in the subsoil at high temperatures until it finds a fuel that accelerates its propagation towards the ground and the heights of the forest.
Regardless of the nature of the fire in a forest, a rapid intervention will facilitate enormously its control and the limitation of the damage caused (Petrov et al. 2020). To ensure sustainable management of their natural heritage, forests are subject to increased surveillance, which is achieved through different methods (Onuekwusi et al., 2020). The oldest one is the observation by the naked eye which covers only limited perimeters, mobilizing important human resources (Petrov et al. 2020). Towards the end of the sixties, remote sensing combined with satellite imagery appeared and managed to extend its coverage over large geographical areas (Fernández et al., 2020). Unfortunately, with this method, the detection of a FF takes a certain lapse of time to be carried out, due to certain spatial and technical constraints of the remote sensing approach used. With the development of wireless communication technologies, wireless sensor networks (WSNs) are emerging (Sadouni et al., 2017), much to the delight of researchers who are constantly proposing new electronic systems for the real-time monitoring of forest environmental variables. Nevertheless, these WSNs suffer from certain shortcomings, particularly energy consumption, connectivity, and limited capacities for processing the collected data (Devadevan et al., 2019).