The forest grows in areas where the soil and climate allow trees to continuously cover the ground. The climate must not be too cold, but not too dry either. Within these conditions different climates give rise to different forests.
Vegetable cover takes the form of a forest when climatic factors, soil and human action create conditions such that the dominant plant species are trees. The variations in the climatic optimum correspond to forests dominated by species particularly suited to specific environmental conditions: hygrophilous, mesophilic and xerophilic.
The climatic optimum, geography and other environmental factors determine the dominant tree species of the forest. Conifers in cold areas, deciduous broad-leaved trees in temperate ones, evergreen broad-leaved trees in tropical ones.
However, the variety of living species makes this subdivision summary: just think of the coniferous forests typical of warm climates such as the Mediterranean pine forests. According to the FAO, the term forest identifies an area greater than 0.5 hectares characterized by trees higher than 5 m and a tree cover greater than 10%.
Following this definition, forests covered an area of 4.06 million hectares in 2020 (30.8% of the global land area). What does the disases of the forests depend on? The article: Functional Ecology of Forest Disease, published on the Annual review of phytopathology, said: "Global change is pressing forest pathologists to solve increasingly complex problems.
We argue that understanding interactive effects between forest pathogens and global warming, globalization, and land use changes may benefit from a functional ecology mindset. Traits can be more informative about ecological functions than species inventories and may deliver a more mechanistic description of forest disease.
Myriad microbes with pathogenic potential interact with forest ecosystems at different organizational levels. Elucidation of functional traits may enable the microbial complexity to be reduced into manageable categories with predictive power.
In this review, we propose guidelines that allow the research community to develop a functional forest pathology approach. We suggest new angles by which functional questions can be used to resolve burning issues on tree disease. Building up functional databases for pathogenicity is key to implementing these approaches."