European beech in the context of Nut (fruit)

An old-growth forest or primary forest is a forest that has developed over a long period of time without disturbance. Due to this, old-growth forests exhibit unique ecological features. The Food and Agriculture Organization of the United Nations defines primary forests as naturally regenerated forests of native tree species where there are no clearly visible indications of human activity and the ecological processes are not significantly disturbed. One-third (34 percent) of the world's forests are primary forests. Old-growth features include diverse tree-related structures that provide diverse wildlife habitats that increases the biodiversity of the forested ecosystem. Virgin or first-growth forests are old-growth forests that have never been logged. The concept of diverse tree structure includes multi-layered canopies and canopy gaps, greatly varying tree heights and diameters, and diverse tree species and classes and sizes of woody debris.

As of 2020, the world has 1.11 billion ha (2.7 billion acres) of primary forest remaining. Combined, three countries (Brazil, Canada, and Russia) host more than half (61 percent) of the world's primary forest. The area of primary forest has decreased by 81 million ha (200 million acres) since 1990, but the rate of loss more than halved in 2010–2020 compared with the previous decade.

In botany, a bud is an undeveloped or embryonic shoot and normally occurs in the axil of a leaf or at the tip of a stem. Once formed, a bud may remain for some time in a dormant condition, or it may form a shoot immediately. Buds may be specialized to develop flowers or short shoots or may have the potential for general shoot development. The term bud is also used in zoology, where it refers to an outgrowth from the body which can develop into a new individual.

Aerial roots are roots growing above the ground. They are often adventitious, i.e. formed from nonroot tissue. They are found in diverse plant species, including epiphytes such as orchids (Orchidaceae), tropical coastal swamp trees such as mangroves, banyan figs (Ficus subg. Urostigma), the warm-temperate rainforest rata (Metrosideros robusta), and pōhutukawa trees of New Zealand (Metrosideros excelsa). Vines such as common ivy (Hedera helix) and poison ivy (Toxicodendron radicans) also have aerial roots.

A hedge or hedgerow is a line of closely spaced (3 feet or closer) shrubs and sometimes trees, planted and trained to form a barrier or to mark the boundary of an area, such as between neighbouring properties. Hedges that are used to separate a road from adjoining fields or one field from another, and are of sufficient age to incorporate larger trees, are known as hedgerows. Often they serve as windbreaks to improve conditions for the adjacent crops, as in bocage country. When clipped and maintained, hedges are also a simple form of topiary.

A hedge often operates as, and sometimes is called, a "live fence". This may either consist of individual fence posts connected with wire or other fencing material, or it may be in the form of densely planted hedges without interconnecting wire. This is common in tropical areas where low-income farmers can demarcate properties and reduce maintenance of fence posts that otherwise deteriorate rapidly. Many other benefits can be obtained depending on the species chosen.