Lichens are complex organisms that arise from the symbiotic relationship between fungi and a photosynthetic partner, typically algae. There are three main types of lichens: foliose, fruticose, and crustose. Foliose lichens are a horizontally growing leafy type of lichen that is always attached to the surface where it is growing. A fruticose lichen is characterized by a coral -like shrubby or bushy growth structure, with upright (pendulous) branches. A crustoselichen is more like a flat crust on a surface or beneath the rock surface or trees.
Forest site productivity is the capacity of a forest to generate products (e.g., wood or biomass) on a certain site with a given tree species and a specified management regime. Site productivity depends both on natural factors inherent to the site and on management-related factors.
A seral stage is a specific vegetation community occurring on a site at some point in time. When the trees in a forest are cleared during a disturbance (e.g., logging or wildfire), the land does not return to its former forested state in a single step. Rather, one vegetation community is gradually replaced by another. Early seral is the first stage in forest development following any disturbance. An early seral, or early successional community is made up of the first colonizers of a forest opening, or by species that survive the disturbance. The mid-seral stage follows the early seral stage, and is the stage when forests naturally thin.
Site Index is a measure of the land’s productive potential for a particular tree species and is expressed as potential tree height at 50 years breast-height age. Breast-height age is the number of years required for a tree to grow from breast height (1.3 m above ground level) to its current height. Site index provides a standardized comparison of productive potential between sites, across a broad range of existing site conditions.