Windthrow at National Park Bavarian Forest

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

, windthrow refers to

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, e.g., including only woody plants with secondary growth, only ...

s uprooted by

wind Wind is the natural movement of atmosphere of Earth, air or other gases relative to a planetary surface, planet's surface. Winds occur on a range of scales, from thunderstorm flows lasting tens of minutes, to local breezes generated by heatin ...

. Breakage of the tree bole (trunk) instead of uprooting is called windsnap. Blowdown refers to both windthrow and windsnap.

Causes

Windthrow is common in all forested parts of the world that experience storms or high wind speeds. The risk of windthrow to a tree is related to the tree's size (height and diameter), the 'sail area' presented by its crown, the anchorage provided by its roots, its exposure to the wind, and the local wind climate. A common way of quantifying the risk of windthrow to a forest area is to model the probability or 'return time' of a wind speed that would damage those trees at that location. Another potential method is the detection of scattered windthrow based on satellite images. Tree

senescence Senescence () or biological aging is the gradual deterioration of Function (biology), functional characteristics in living organisms. Whole organism senescence involves an increase in mortality rate, death rates or a decrease in fecundity with ...

can also be a factor, where multiple factors contributing to the declining health of a tree reduce its anchorage and therefore increase its susceptibility to windthrow. The resulting damage can be a significant factor in the development of a forest. Windthrow can also increase following

logging Logging is the process of cutting, processing, and moving trees to a location for transport. It may include skidder, skidding, on-site processing, and loading of trees or trunk (botany), logs onto logging truck, trucksforests managed specifically for

timber Lumber is wood that has been processed into uniform and useful sizes (dimensional lumber), including beams and planks or boards. Lumber is mainly used for construction framing, as well as finishing (floors, wall panels, window frames). ...

. The removal of trees at a forest's edge increases the exposure of the remaining trees to the wind. Trees that grow adjacent to lakes or other natural forest edges, or in exposed situations such as hill sides, develop greater rooting strength through growth feedback with wind movement, i.e. 'adaptive' or 'acclimative' growth. If a tree does not experience much wind movement during the

stem exclusion Stem or STEM most commonly refers to: * Plant stem, a structural axis of a vascular plant * Crown group#Stem groups, Stem group * Science, technology, engineering, and mathematics Stem or STEM can also refer to: Language and writing * Word stem, ...

phase of stand succession, it is not likely to develop a resistance to wind. Thus, when a fully or partially developed stand is bisected by a new road or by a

clearcut Clearcutting, clearfelling or clearcut logging is a forestry/logging practice in which most or all trees in an area are uniformly cut down. Along with shelterwood and seed tree harvests, it is used by foresters to create certain types of fore ...

, the trees on the new edge are less supported by neighbouring trees than they were and may not be capable of withstanding the higher forces which they now experience. Trees with heavy growths of

ivy ''Hedera'', commonly called ivy (plural ivies), is a genus of 12–15 species of evergreen climbing or ground-creeping woody plants in the family Araliaceae, native to Western Europe, Central Europe, Southern Europe, Macaronesia, northwestern ...

wisteria ''Wisteria'' is a genus of flowering plants in the legume family, Fabaceae (Leguminosae). The genus includes four species of woody twining vines that are native to China, Japan, Korea, Vietnam, southern Canada, the Eastern United States, and nor ...

, or

kudzu Kudzu (), also called Japanese arrowroot or Chinese arrowroot, is a group of climbing, coiling, and trailing deciduous perennial vines native to much of East Asia, Southeast Asia, and some Pacific islands. It is invasive species, invasive in ...

are already stressed and may be more susceptible to windthrow, as the additional foliage increases the tree's sail area. Trees with decayed trunk,

fungus A fungus (: fungi , , , or ; or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified as one ...

-induced

canker A plant canker is a small area of dead tissue, which grows slowly, often over years. Some cankers are of only minor consequence, but others are ultimately lethal and therefore can have major economic implications for agriculture and horticultur ...

s, and borer damages are more susceptible to windsnap. Young trees (less than 100 years old) can snap when pushed by wind gusts, while older trees usually do not snap but are uprooted.

Ecological effects

Windthrow disturbance generates a variety of unique ecological resources on which certain forest processes are highly dependent. Windthrow can be considered a cataclysmic abiotic factor that can generate an entire new chain of seral plant succession in a given area.C.Michael Hogan. 2010
''Abiotic factor''. Encyclopedia of Earth. eds Emily Monosson and C. Cleveland. National Council for Science and the Environment
Washington DC Windthrow can also be considered to act as a rejuvenating process whereby regeneration is made possible with new resource availability. Severe uprooting opens bare patches of mineral soil that can act as seed sinks. These patches have been shown, in the

Pacific Northwest The Pacific Northwest (PNW; ) is a geographic region in Western North America bounded by its coastal waters of the Pacific Ocean to the west and, loosely, by the Rocky Mountains to the east. Though no official boundary exists, the most common ...

of the United States, to have higher

biodiversity Biodiversity is the variability of life, life on Earth. It can be measured on various levels. There is for example genetic variability, species diversity, ecosystem diversity and Phylogenetics, phylogenetic diversity. Diversity is not distribut ...

than the surrounding forest floor. Additionally, the gap created in the forest canopy when windthrow occurs yields an increase in light, moisture, and nutrient availability in near proximity to the disturbance. Toppled trees have the potential to become

nurse log A nurse log is a fallen tree which, as it decays, provides ecological facilitation to seedlings. Broader definitions include providing shade or support to other plants. Some of the advantages a nurse log offers to a seedling are: water, moss thick ...

s, nurturing habitats for other forest organisms. Tree throws contribute to bedrock weathering and

soil formation Soil formation, also known as pedogenesis, is the process of soil genesis as regulated by the effects of place, environment, and history. Biogeochemical processes act to both create and destroy order ( anisotropy) within soils. These alteration ...

. In thin soils, fresh bedrock fragments are a large proportion of the upturned rootwad, but trees are sparse, so rates of weathering are low; in intermediate-depth soils less rock is upturned, but trees are more common, so weathering reaches a maximum; in soils deeper than the depth of roots, no bedrock is upturned, and weathering is slow. The advent of trees roughly 370 million years ago led to dramatic ecosystem changes, as before then bedrock weathering was too slow to maintain thick soils in hilly terrain.

References

Alabama Hiking Trail Society
Cited Dec. 2007
USFS "Trail Information— State Route 410 Mather Memorial Parkway / Clearwater"
Online bulletin board. Cited Dec. 15, 2007

Bibliography

* Nina G Ulanova, Forest Ecology and Management; Volume 135, Issues 1–3, 15 September 2000, Pages 155–167; ''The effects of windthrow on forests at different spatial scales: a review'' * Canham, C.D. & Loucks, O.L. (1984) Catastrophic windthrow in the presettlement forests of Wisconsin. Ecology, 65, 803–809. * Canham, C.D., Denslow, J.S., Platt, W.J., Runkle, J.R., Spies, T.A. & White, P.S. (1990) Light regimes beneath closed canopies and tree-fall gaps in temperate and tropical forests. Canadian Journal of Forest Research, 20, 620–631. * Canham, C.D., Papaik, M.J. & Latty, E.J. (2001) Interspecific variation in susceptibility to windthrow as a function of tree size and storm severity for northern hardwood tree species. Canadian Journal of Forest Research, 31, 1–10. * Mladenoff, D.J. (1987) Dynamics of nitrogen mineralization and nitrification in hemlock and hardwood treefall gaps. Ecology, 68, 1171–1180. * Peterson, C.J. & Pickett, S.T.A. (1995) Forest reorganization – A case study in an old-growth forest catastrophic blowdown. Ecology, 76, 763–774. * Pickett, S.T.A. & White (1985) Patch dynamics: a synthesis. The Ecology of Natural Disturbance and Patch Dynamics (eds S.T.A.Pickett & P.S.White), pp. 371–384. Academic Press, Orlando, FL. * Metcalfe, D. J., Bradford, M. G., & Ford, A. J. (2008). Cyclone damage to tropical rain forests: Species‐and community‐level impacts. Austral Ecology, 33(4), 432-441. {{Authority control Biogeomorphology Dead wood Forest ecology Wind

Causes

Ecological effects

See also

References

Bibliography