Doctoral training in forestry is a first at the Higher National School of Forests (HNSF). This offer is seen as a requirement for students graduating from the HNSF, as well as for forestry graduates from other national and international universities. This pioneering choice is motivated by the nationwide shortage of doctors in the field of forestry. This crucial decision is also guided by the need to respond to an emerging and urgent demand, dictated by the imperatives of sustainable development, the growing recognition of the importance of conserving our forest heritage, preserving the country's forest resources and the climate changes, mainly warming, undergone by all ecosystems, essentially the forest ecosystem. Our forests are subject to a series of disturbances that are strongly influenced by climate. The aim is to gain a better understanding of the mechanisms and issues involved in the current massive loss of forest ecosystems in Algeria, as well as their ecosystem services, taking into account the new political, economic and social dynamics that are shaping our rich forest heritage, also helping to stabilize the climate, regulate various ecosystems, protect biodiversity and support the livelihoods of some specific populations. This doctoral program will provide doctoral students with an integrated and solid training in the field of forestry, covering the different scales of intervention : local, regional and national, which are directly related to the major national research axes. This will enable doctoral students to gain access to the world of scientific research, particularly on problems linked to the risks of land and soil degradation in arid and semi-arid zones, the health of natural forests, such as the decline of forest plant species (for which it is crucial to understand the morphological and physiological aspects), biological invasions and forest fires, which are interconnected problems affecting forest ecosystems; which can alter tree species composition, change forest succession and reduce specific and phyto-genetic biodiversity. All these impacts on trees and forests will inevitably have widespread effects on the forestry sector.