Crown closure, in

forestry Forestry is the science and craft of creating, managing, planting, using, conserving and repairing forests, woodlands, and associated resources for human and environmental benefits. Forestry is practiced in plantations and natural stands. ...

, is a measure of

forest canopy In biology, the canopy is the aboveground portion of a plant cropping or crop, formed by the collection of individual plant crowns. In forest ecology, canopy also refers to the upper layer or habitat zone, formed by mature tree crowns an ...

coverage. Crown closure and crown cover are two slightly different measures of the forest canopy and that determine the amount of light able to penetrate to the forest floor. Crown closure, also known as canopy closure, is an integrated measure of the canopy "over a segment of the sky hemisphere above one point on the ground". Crown cover is the proportion of a stand covered by the crowns of live trees. A forest stand can have a crown cover of 100% and a crown closure less than 100%. Typical stands with 100% cover but low closure are coffee

agroforestry Agroforestry is a land use management system in which trees or shrubs are grown around or among crops or pastureland. Trees produce a wide range of useful and marketable products from fruits/nuts, medicines, wood products, etc. This intentional ...

stands, where overlapping parasol-shaped crowns ensure complete cover but still allow light to penetrate at an oblique angle to the forest floor.

Basic concepts

Crown closure helps predict volume, stand density,

crown width A crown is a traditional form of head adornment, or hat, worn by monarchs as a symbol of their power and dignity. A crown is often, by extension, a symbol of the monarch's government or items endorsed by it. The word itself is used, parti ...

, and

crown competition factor A crown is a traditional form of head adornment, or hat, worn by monarchs as a symbol of their power and dignity. A crown is often, by extension, a symbol of the monarch's government or items endorsed by it. The word itself is used, parti ...

. Crown closure is often determined using aerial photographs because ground evaluations become difficult to obtain. Stands are usually placed in to different classes (1-6) after viewing the

aerial photographs Aerial photography (or airborne imagery) is the taking of photographs from an aircraft or other airborne platforms. When taking motion pictures, it is also known as aerial videography. Platforms for aerial photography include fixed-wing aircra ...

. # Very Sparse 1–9% # Sparse 10–29% # Low 30–49% # Medium 50–69% # Dense 70–84% # Very Dense 85–100% Although sometimes referred to as canopy cover and canopy closure, crown closure is different from these two concepts. Canopy cover represents the aggregate of all vertically projected tree crowns onto the ground surface, while canopy closure represents the amount of the sky obscured by the canopy from a certain point on the ground.

Ground measurement

Each tree’s measurements are used to calculate the area projected by the

crown A crown is a traditional form of head adornment, or hat, worn by monarchs as a symbol of their power and dignity. A crown is often, by extension, a symbol of the monarch's government or items endorsed by it. The word itself is used, partic ...

onto the ground. Summing the crown areas for all trees measured on a fixed plot area and dividing by the ground area will give the crown closure. The "moosehorn" crown closure estimator is a device for measuring crown closure from the ground. Other methods for estimating crown closure include the use of line-intercept, spherical densiometer, and hemispherical photography.Fiala, A.C.S.. Garman, S.L., and A.N. Gray. 2006. Comparison of five canopy cover estimation techniques in the western Oregon Cascades.

Forest Ecology and Management ''Forest Ecology and Management'' is a semimonthly peer-reviewed scientific journal covering forest ecology and the management of forest resources. The journal publishes research manuscripts that report results of original research, review articles ...

232:186-197. Exact cover measurements should be made in vertical direction, or the cover percent will be overestimated.Jennings, S. B., Brown, N. D., & Sheil, D. 1999. Assessing forest canopies and understorey illumination: canopy closure, canopy cover and other measures. Forestry 72(1): 59–74.

Aerial measurement

Aerial photographs made at scales of 1:15,000 or larger can be used to determine crown closure estimates, usually done by ocular interpretation, by grouping stands into percent classes.Avery, T.E. and Burkhart, H.E. 2002. Forest Measurements. 5th edition. McGraw Hill, New York. 456 p. Low density stands make for an easy ocular estimation, but as the stand density increases the ocular estimates become more difficult to obtain. In dense stands, overestimates or underestimates of crown closure can be made and predicting value of stand volume becomes more reduced.Spur, S.H. 1952.

Forest Inventory Forest inventory is the systematic collection of data and forest information for assessment or analysis. An estimate of the value and possible uses of timber is an important part of the broader information required to sustain ecosystems. When taki ...

Ronald Press, New York. 476p.

References

{{Reflist Forest ecology

Basic concepts

Ground measurement

Aerial measurement

See also

References