In forestry, windthrow refers to trees uprooted by wind. Breakage of the tree bole (trunk) instead of uprooting is called windsnap. [1] Blowdown refers to both windthrow and windsnap.
In forestry, windthrow refers to trees uprooted by wind. Breakage of the tree bole (trunk) instead of uprooting is called windsnap. [1] Blowdown refers to both windthrow and windsnap.
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. [2] Tree senescence 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, especially in young forests managed specifically for timber. 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 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, 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, wisteria, or kudzu 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-induced cankers and borer damages are more susceptible to windsnap. [1]
Young trees (less than 100 years old) can snap when pushed by wind gusts, while older trees usually do not snap but are uprooted. [3]
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. [4] 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 of the United States, to have higher biodiversity 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 logs, nurturing habitats for other forest organisms.
Tree throws contribute to bedrock weathering and soil formation. 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. [3] 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. [3]
In ecology, edge effects are changes in population or community structures that occur at the boundary of two or more habitats. Areas with small habitat fragments exhibit especially pronounced edge effects that may extend throughout the range. As the edge effects increase, the boundary habitat allows for greater biodiversity.
Ecological succession is the process of change in the species that make up an ecological community over time.
An old-growth 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 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.
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 forest ecosystems and to promote select species that require an abundance of sunlight or grow in large, even-age stands. Logging companies and forest-worker unions in some countries support the practice for scientific, safety and economic reasons, while detractors consider it a form of deforestation that destroys natural habitats and contributes to climate change. Environmentalists, traditional owners, local residents and others have regularly campaigned against clearcutting, including through the use of blockades and nonviolent direct action.
A secondary forest is a forest or woodland area which has regenerated through largely natural processes after human-caused disturbances, such as timber harvest or agriculture clearing, or equivalently disruptive natural phenomena. It is distinguished from an old-growth forest, which has not recently undergone such disruption, and complex early seral forest, as well as third-growth forests that result from harvest in second growth forests. Secondary forest regrowing after timber harvest differs from forest regrowing after natural disturbances such as fire, insect infestation, or windthrow because the dead trees remain to provide nutrients, structure, and water retention after natural disturbances. Secondary forests are notably different from primary forests in their composition and biodiversity; however, they may still be helpful in providing habitat for native species, preserving watersheds, and restoring connectivity between ecosystems.
Forest dynamics describes the underlying physical and biological forces that shape and change a forest ecosystem. The continuous state of change in forests can be summarized with two basic elements: disturbance and succession.
Forest ecology is the scientific study of the interrelated patterns, processes, flora, fauna and ecosystems in forests. The management of forests is known as forestry, silviculture, and forest management. A forest ecosystem is a natural woodland unit consisting of all plants, animals, and micro-organisms in that area functioning together with all of the non-living physical (abiotic) factors of the environment.
A tree throw or tree hole is a bowl-shaped cavity or depression created in the subsoil by a tree.
In ecology, a disturbance is a temporary change in environmental conditions that causes a pronounced change in an ecosystem. Disturbances often act quickly and with great effect, to alter the physical structure or arrangement of biotic and abiotic elements. A disturbance can also occur over a long period of time and can impact the biodiversity within an ecosystem.
Temperate deciduous or temperate broad-leaf forests are a variety of temperate forest 'dominated' by deciduous trees that lose their leaves each winter. They represent one of Earth's major biomes, making up 9.69% of global land area. These forests are found in areas with distinct seasonal variation that cycle through warm, moist summers, cold winters, and moderate fall and spring seasons. They are most commonly found in the Northern Hemisphere, with particularly large regions in eastern North America, East Asia, and a large portion of Europe, though smaller regions of temperate deciduous forests are also located in South America. Examples of trees typically growing in the Northern Hemisphere's deciduous forests include oak, maple, basswood, beech and elm, while in the Southern Hemisphere, trees of the genus Nothofagus dominate this type of forest. Temperate deciduous forests provide several unique ecosystem services, including habitats for diverse wildlife, and they face a set of natural and human-induced disturbances that regularly alter their structure.
Cross-boundary subsidies are caused by organisms or materials that cross or traverse habitat patch boundaries, subsidizing the resident populations. The transferred organisms and materials may provide additional predators, prey, or nutrients to resident species, which can affect community and food web structure. Cross-boundary subsidies of materials and organisms occur in landscapes composed of different habitat patch types, and so depend on characteristics of those patches and on the boundaries in between them. Human alteration of the landscape, primarily through fragmentation, has the potential to alter important cross-boundary subsidies to increasingly isolated habitat patches. Understanding how processes that occur outside of habitat patches can affect populations within them may be important to habitat management.
Patch dynamics is an ecological perspective that the structure, function, and dynamics of ecological systems can be understood through studying their interactive patches. Patch dynamics, as a term, may also refer to the spatiotemporal changes within and among patches that make up a landscape. Patch dynamics is ubiquitous in terrestrial and aquatic systems across organizational levels and spatial scales. From a patch dynamics perspective, populations, communities, ecosystems, and landscapes may all be studied effectively as mosaics of patches that differ in size, shape, composition, history, and boundary characteristics.
Shelterwood cutting removes part of the old forest stand to allow for a natural establishment of seedlings under the cover of the remaining trees. Initial cuttings give just enough light to allow for the regeneration of desired species. Subsequent cuttings give the new seedlings more light and fully pass the growing space to the new generation. Shelterwood systems have many variations and can be adapted to site conditions and the goals of the landowner. There are concerns associated with this silvicultural system due to windthrow and high costs as well as advantages due to improved aesthetics and cost savings from natural regeneration.
In the context of ecological stability, resistance is the property of communities or populations to remain "essentially unchanged" when subject to disturbance. The inverse of resistance is sensitivity.
Heterobasidion irregulare is a tree root rotting pathogenic fungus that belongs to the genus Heterobasidion, which includes important pathogens of conifers and other woody plants. It has a wide host and geographic range throughout North America and causes considerable economic damage in pine plantations in the United States. This fungus is also a serious worry in eastern Canada. Heterobasidion irregulare has been introduced to Italy (Lazio)(modifica) where it has been responsible for extensive tree mortality of stone pine. Due to the ecology, disease type, host range/preference, interfertility group, and genetic information, H. irregulare was designated a new species and distinguished from Heterobasidion occidentale.
Gap dynamics refers to the pattern of plant growth that occurs following the creation of a forest gap, a local area of natural disturbance that results in an opening in the canopy of a forest. Gap dynamics are a typical characteristic of both temperate and tropical forests and have a wide variety of causes and effects on forest life.
Pit and mounds are small, persistent microtopographical features that present themselves after a disturbance event occurs and uproots trees via windthrow. The uprooted tree falls, and a pit forms in the forest floor where the root mass and associated soil matrix used to be. Eventually after a period of time in which the roots decay, the associated soil matrix that was pulled out of the ground with the roots falls back to the ground, creating a corresponding mound.
Climate change in Alaska encompasses the effects of climate change in the U.S. state of Alaska.
In ecology, a light gap is a break in forest canopy or similar barrier that allows young plants to grow where they would be otherwise inhibited by the lack of light reaching the seedbed. Light gaps form predominantly when a tree falls, and thus produces an opening in the forest canopy. Light gaps are important for maintaining diversity in species-rich ecosystems.
Julie Sloan Denslow is an American botanist, ecologist and biologist. She grew up in South Florida, and always loved nature. She graduated from Coral Gables Senior High School in 1960. She has contributed to the field of ecology through her work with and research of tropical ecosystems. Earlier in her career, she spent significant time in the field in tropical locations such as Costa Rica and Panama, as well as in temperate locations in Louisiana. and later on in her career she worked more in the office and classroom, but still spent the occasional day in the field. She has focused on research involving the ecology of exotic invasive plant species, and on ecosystem reactions and recovery following disturbances. Denslow is also a strong supporter of gender equality in the natural sciences, pushing for equal representation of women involved in tropical research and leadership during a 2007 Gender Committee Meeting within the Association for Tropical Biology and Conservation (ATBC). Her most notable contribution to tropical research is her paper "Gap Partitioning among Tropical Rainforest Trees", published in 1980.
Damage such as this often renders a tree bole susceptible to "windsnap" at the point of injury.
