Forest Lichen

Forest

A forest is an ecosystem characterized by a dense community of trees. Hundreds of definitions of forest are used throughout the world, incorporating factors such as tree density, tree height, land use, legal standing, and ecological function. The United Nations' Food and Agriculture Organization (FAO) defines a forest as, "Land spanning more than 0.5 hectares with trees higher than 5 meters and a canopy cover of more than 10 percent, or trees able to reach these thresholds in situ. It does not include land that is predominantly under agricultural or urban use." Using this definition, Global Forest Resources Assessment 2025 found that forests covered 4.14 billion hectares, or approximately 31 percent of the world's land area in 2025.

Lichen

A lichen is a hybrid colony of algae or cyanobacteria living symbiotically among filaments of multiple fungus species, along with bacteria embedded in the cortex, or "skin", in a mutualistic relationship. Lichens are the lifeform that first brought the term symbiosis into biological context.

forest

Noun

1. A dense uncultivated tract of trees and undergrowth, larger than woods.
2. Any dense collection or amount.

Verb

1. To cover an area with trees.

lichen

Noun

1. Any of many symbiotic organisms, being associations of algae and fungi, often found as white or yellow-to-blue–green patches on rocks, old walls, etc.
2. Something which gradually spreads across something else, causing damage.

Verb

1. To cover with lichen.