On Thu, 17 Apr 2014 21:09:05 -0400 Meade Dillon <dillonm...@gmail.com> wrote:
> Squirrels are VERY important. They open pine cones and bury the seeds, > bury acorns, walnuts, butternut, etc. Without squirrels, we'd have no > forests. Some misguided souls think forest fires open pine cones which > allow new pine trees to sprout and grow, but that is an old wives > tale... Actually, it seems it is not an old wives tale. ---------------------------- http://www.nps.gov/fire/wildland-fire/learning-center/educator-resources/lesson-plans/fire-adaptation.cfm Retention of seeds by plants and stimulation of seed dispersal by fire are other examples of fire-adaptive strategies. A number of pine species have pine cones that open only after a fire. These cones are said to be serotinous (pronounced sir-ot-in-ous). Jack pines have cones that are held closed by a resin that is sensitive to high temperatures. These cones will not open to release their seeds until the critical temperature is reached. Lodgepole pine cones (a western U.S. variety of tree) vary from serotinous to free-opening. When these trees grow in areas subject to frequent fires, the cones are serotinous. However, if this species grows in areas where fire is less frequent, the cones open and release their seeds more frequently without fire. ---------------------------- http://interwork.sdsu.edu/fire/resources/conifer-forest.htm Coulter pine displays variation in degree of cone serotiny (cones that open with fire). Not every Coulter pine cone is serotinous. There are some trees with no serotinous cones and some with all serotinous cones and everything in between. Serotiny is prevalent in Coulter pines occurring withing chaparral or oak woodland. Cones of Coulter pine in these communities typically do not open until heated by fire. Consequently, the bulk of Coulter pine regeneration in these communities occurs after fire. Coulter pine ecotypes associated with coast live oak, however, typically bear cones that open at maturity or shortly thereafter. Coulter pine seedling development is best in mineral soil in open areas; such conditions are created by fire. ---------------------------- http://indianapublicmedia.org/amomentofscience/lodgepole-pine-trees-love-forest-fires/ The summer of 2012 was certainly a scorcher, with forest fires blazing across the Western United States. To humans, wildfires are often scary and dangerous. If you were a lodgepole pine cone, though, you would be eagerly awaiting the blazing heat of those flames! How come lodgepole pine cones like fire so much? When lodgepole pines grow, especially in areas that are prone to forest fires, their cones are tightly sealed. A layer of resin and woody tissue sticks the cones’ scales together. The seeds are locked in tight, and the cones can’t open unless they’re exposed to VERY high temperatures–the type of temperatures that fire provides. “Serotinous” is a scientific term for a seed that requires an environmental trigger in order to be released. For the lodgepole pine, that trigger is heat. And since big fires don’t come along very often, those well sealed pine cones have to be extremely patient. They can hang out on the tree branches for several years waiting for enough heat to open them up! Years of waiting So, if multiple years’ worth of cones can accumulate, then a lot of new pine trees sure must sprout up after a fire. Lodgepole pines are famous for colonizing post fire landscapes. The seeds love the carbon rich soil that fire leaves behind, and seedlings pop up almost immediately. They grow into dense stands of trees, and before you know it, there’s a whole new crop of serotinous cones waiting in anticipation for the next fire to blaze through. ---------------------------- http://techalive.mtu.edu/meec/module11/FireandJackPine.htm Why Do Jack Pine Trees Grow After Fire? Michigan Environmental Education Curriculum Forest Ecosystem New jack pine seedlings grow well after a hot fire. Fire causes the cone of an older jack pine tree to open up and release seeds. Cones that need heat, such as the heat from fire, in order to open are called serotinous cones. When the heat causes the cones to open, seeds are released and fall to the ground (see animation below). In Michigan, the Department of Natural Resources (DNR) lights fires in the Jack Pine Ecosystems to help new jack pine trees grow. This is because the Kirtland's Warbler will only build nests under the young jack pine trees. ---------------------------- csfs.colostate.edu/pdfs/06307.pdf Lodgepole Pine Lodgepole pine forests are very adapted to a natural fire regime. Regeneration of new lodgepole seedlings can be rapid (as little as two to three years). Lodgepole bark is thin in comparison to that of ponderosa pine. Temperatures lethal to the cambium are common. A unique characteristic of lodgepole pine is its serotinous cones. The cone scales can remain closed for several years because of a resin coating. During an intense fire this resin melts away allowing the cone scales to open, thus releasing the seed. After a fire, a massive number of seeds are released. An intense fire also exposes mineral soil to provide a good seed bed. ---------------------------- http://michigan.gov/dnr/0,1607,7-153-10370_12146_12212-60297--,00.html Jack Pine (Pinus banksiana) Among all Michigan tree species, the jack pine is uniquely adapted to exist and reproduce on the hottest and driest sites in Michigan. It thrives on dune sand and on the sandy glacial plains, where it often occurs in dense stands. It is called a "fire species" because wildfires sweep through jack pine stands, killing the trees and preparing the ground for a new stand, thus releasing seeds from its cones. Jack pine was once thought to poison the ground on which it stood because no other trees and few ground plants would grow near it. In truth, many species grow with jack pine. Most jack pine cones are sealed with a special resin. This resin prevents the cones from drying out and releasing their seeds except under certain conditions. The resin melts at 112 degrees F, a temperature easily reached during a forest fire, but which also may be achieved on bare ground in open sunlight on a bright summer day. After the resin is melted, the cones open, releasing the seeds from within. These resinous cones are called serotinous cones. Not all jack pine cones are serotinous. Almost every jack pine has a few cones each year which are non serotinous. These cones open in the fall and provide a source of seeds in case fires do not occur. Given proper conditions, the seeds will germinate almost immediately after falling, but if moisture is lacking when they fall, some seeds go into dormancy which may last up to three years or more. Studies have shown jack pine seedlings will continue to sprout up to three years after a forest fire. This adaptation guards against the loss of all of the young seedlings due to an unusually dry summer or because of a hard frost. Jack pines in Michigan are often crooked and short generally not a favorite tree of most people. However, in some places in the Upper Peninsula and farther north into Ontario, they grow much straighter and taller. Much of the difference is due to insects and other problems that plague the jack pine in lower Michigan, which is the southern limit of the tree's natural range. The long wood fibers of jack pine make it ideal for the manufacture of strong papers. Harvest is usually by clearcut to mimic the effects of a wildfire. The soil is then prepared for seeding or planting, and a new stand is established. Jack pine pollen is shed in late May or early June and sometimes forms large clouds resembling smoke rising from the tops of the trees. It settles on the ground and forms a yellow border around puddles and a thin, yellow film on everything within miles. ---------------------------- http://www.fs.fed.us/database/feis/plants/tree/pinser/all.html REGENERATION PROCESSES: The specific epithet of pond pine, serotina, means "late" and refers to the delayed opening of cones. Cones often persist for 2 to 8 years, giving the tree the appearance of being a prolific seed producer [8,14]. All pond pine cones are probably closed when they first mature [79]. Viability does not decrease in cones that remain closed for as long as 3 years [8]. Cones older than 5 years may open individually following weathering and insect depredations; sound seed may be sparse in cones more than 5 years old [79]. Seed is released from older, open cones of pond pine during 2 seasonal periods: April through September and October through January [8,16]. Regeneration of pond pine is hampered by 2 problems under average conditions. First, serotinous pond pine cones often require heat to open the scaled cones, and 2nd, continual moistness of the organic soil provides an excellent growth medium for intense competitors such as other trees, evergreen brush, and switchcane (Arundinaria gigantea ssp. tecta) [16]. Pond pine cones open and release seeds soon after exposure to heat from fire. Intensity of heat does not adversely reduce viability of seeds. Even badly charred cones release seeds that are capable of germination. Mature cones can be opened by exposure to 333 to 336 oF (167-169 oC) dry heat for 20 seconds or by immersion in boiling water for a similar period [8]. Optimum stratification of pond pine seeds is 30 days at 33-41oF (0.5-5 oC) in a moist medium [5,46]. Germination occurs in 24 days [5]. Pond pine seeds germinated in a nursery were unable to survive full saturation conditions [46]. ---------------------------- http://oscodaherald.com/stories/Forest-Service-to-conduct-prescribed-burns-in-Oscoda-County,99161 [U.S. Forest Service Public Relations Manager Kate] Salm said in some cases where fire is used to aid wildlife, it can have a huge impact for plants and creatures. According to Forest Service biologists, fire is a natural part of many ecosystems in the Huron-Manistee National Forests. Species such as white-tailed deer, turkey, butterflies, grouse and turtles use burned areas for food, cover and a place to raise their young. Generating new habitat for the endangered Kirtland’s warbler, a bird that is largely only found in Michigan’s juvenile jack pine forests, is another reason for the burns, Salm said. A surprising reason, Salm said, is to create habitat for the monarch butterfly, which she said has been on the decline over the past years. The new fire areas create habitat for the monarch’s favorite flowering plant, the milkweed, to grow, she said. Another motive behind for prescribed burns is to allow native trees, like jack pine and red pine, to release seeds. “The trees will drop their cones on the ground; they need that heat from the fire to open, so the seeds will spread,” she said. “That is something with that tree that has developed over thousands of years.” The fires also put large amounts of nutrients back into the soil, causing new plant life to flourish. “It doesn’t take long after a fire,” she said. “You see how green the grass is after a prescribed fire. The ash puts a lot of nutrients back into the soil.” Salm said fire has been a natural process with Michigan’s ecosystem since before humans were even in Michigan. “Before Europeans most of it was caused by nature, often by lightning strikes,” she said. ---------------------------- _______________________________________ http://www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com All posts are the result of individual contributors and as such, those individuals are responsible for the content of the post. The list owner has no control over the content of the messages of each contributor.
