HK Kwun Tong 麗港公園 Laguna Park Tree evening sunset

The crown of a plant refers to the total of an individual plant's aboveground parts, including stems,

leaves A leaf ( : leaves) is any of the principal appendages of a vascular plant stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, ste ...

, and reproductive structures. A

plant community A plant community is a collection or association of plant species within a designated geographical unit, which forms a relatively uniform patch, distinguishable from neighboring patches of different vegetation types. The components of each plant ...

canopy Canopy may refer to: Plants * Canopy (biology), aboveground portion of plant community or crop (including forests) * Canopy (grape), aboveground portion of grapes Religion and ceremonies * Baldachin or canopy of state, typically placed over an a ...

consists of one or more plant crowns growing in a given area. The crown of a

woody plant A woody plant is a plant that produces wood as its structural tissue and thus has a hard stem. In cold climates, woody plants further survive winter or dry season above ground, as opposite to herbaceous plants that die back to the ground until ...

(

tree In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, including only woody plants with secondary growth, plants that ar ...

shrub A shrub (often also called a bush) is a small-to-medium-sized perennial woody plant. Unlike herbaceous plants, shrubs have persistent woody stems above the ground. Shrubs can be either deciduous or evergreen. They are distinguished from tree ...

liana A liana is a long- stemmed, woody vine that is rooted in the soil at ground level and uses trees, as well as other means of vertical support, to climb up to the canopy in search of direct sunlight. The word ''liana'' does not refer to a ...

) is the

branch A branch, sometimes called a ramus in botany, is a woody structural member connected to the central trunk of a tree (or sometimes a shrub). Large branches are known as boughs and small branches are known as twigs. The term ''twig'' usually ...

es,

, and reproductive structures extending from the trunk or main stems. Shapes of crowns are highly variable. The major types for trees are the excurrent branching habit resulting in

conoid In geometry a conoid () is a ruled surface, whose rulings (lines) fulfill the additional conditions: :(1) All rulings are parallel to a plane, the '' directrix plane''. :(2) All rulings intersect a fixed line, the ''axis''. The conoid is a r ...

shapes and decurrent (deliquescent) branching habit, resulting in round shapes. Crowns are also characterized by their width, depth, surface area, volume, and density. Measurements of crowns are important in quantifying and qualifying plant health, growth stage, and efficiency. Major functions of the crown include light energy assimilation, carbon dioxide absorption and release of oxygen via

photosynthesis Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemical energy is stored in ...

, energy release by

respiration Respiration may refer to: Biology * Cellular respiration, the process in which nutrients are converted into useful energy in a cell ** Anaerobic respiration, cellular respiration without oxygen ** Maintenance respiration, the amount of cellul ...

, and movement of water to the atmosphere by transpiration. These functions are performed by the leaves.

Crown classes

Trees can be described as fitting different crown classes. Commonly used are Kraft's classes. Kraft designated these social classes based on temperate and boreal forests in

Central Europe Central Europe is an area of Europe between Western Europe and Eastern Europe, based on a common historical, social and cultural identity. The Thirty Years' War (1618–1648) between Catholicism and Protestantism significantly shaped the ar ...

, so they do not necessarily work with every forest type in the world. Kraft wrote in German so here are his classes with translations: * 1 v vorherrschend (predominant) * 2 h herrschend (dominant) * 3 m mitherrschend (co-dominant) * 4 b beherrscht (dominated / suppressed) * 5 u unterständig (inferior) this is then split into 2 subclasses 5a (shade tolerant trees) and 5b (dying crowns / dying trees) Often it has been simplified to Dominant, Co-dominant and Suppressed. Also IUFRO developed a tree classification it is based on three components with numbers that then aggregate to give a coded classification thus: Ecological criteria Height component (Stand layer / Height class): * 100 Overstorey / Overlayer * 200 Middlestorey / Middlelayer * 300 Understorey / Underlayer Vitality component (Tree vigor / vitality): * 10 Lush * 20 Normal * 30 Retarded Future growth potential component (Developmental tendency / conversion tendency): * 1 High * 2 Average * 3 Lagging and then additionally Silvicultural Criteria Commercial worth * 400 Valuable, outstanding tree * 500 Usable, wood * 600 Poor to Unusable Quality Trunk class * 40 Valuable wood (≥50% of the trunk is high-quality timber) * 50 Normal wood (≥50% of the trunk is normal-quality timber) * 60 Substandard wood (<50% of the trunk is normal-quality timber) Crown class *4 Deep crown (>½ the tree length) *5 Medium crown *6 Shallow crown (<¼ the tree length) While both Kraft and IUFRO classifications are aimed at describing individual tree crowns both can and are applied to describe whole layers or storeys.National Forest Inventories: Contributions to Forest Biodiversity Assessments Gherardo Chirici, Susanne Winter, Ronald E. McRoberts Springer Science & Business Media, 2011 - 206pp

References

External links

Tree crown
{{Authority control Plant morphology

Crown classes

See also

References

Further reading

External links