|
''Pinus palustris'', commonly known as the longleaf pine, is a pine native to the southeastern United States, found along the coastal plain from eastern Texas to southeast Virginia, extending into northern and central Florida. It reaches a height of and a diameter of . In the past, they reportedly grew to with a diameter of . The bark is thick, reddish-brown, and scaly. The leaves are dark green and needle-like, and occur in bundles of three. They often are twisted and in length. It is one of the two southeastern U.S. pines with long needles, the other being slash pine. The cones, both female seed cones (ovulate strobili) and male pollen cones (staminate strobili), are initiated during the growing season before buds emerge. Pollen cones begin forming in their buds in July, while seed conelets are formed during a relatively short period of time in August. Pollination occurs early the following spring, with the male cones long. The female (seed) cones mature in about twenty months from pollination; when mature they are yellow-brown in color, long, and broad, opening to , and have a small, but sharp, downward-pointing spine on the middle of each scale. The seeds are long, with a wing. Longleaf pine takes 100 to 150 years to become full size and may live to be 500 years old. When young, they grow a long taproot, which usually is long; by maturity they have a wide spreading lateral root system with several deep 'sinker' roots. It grows on well-drained, usually sandy soil, often in pure stands. In northern Alabama, it sometimes occurs on clay soil. The scientific name meaning, "of marshes," is a misunderstanding on the part of Philip Miller who described the species, after seeing longleaf pine forests with temporary winter flooding. Longleaf pine also is known as being one of several species grouped as a southern yellow pine or longleaf yellow pine, and in the past as pitch pine (a name dropped as it caused confusion with pitch pine, ''Pinus rigida''). ==Ecology== Longleaf pine is highly pyrophytic (resistant to wildfire). Periodic natural wildfire selects for this species by killing other trees, leading to open longleaf pine forests or savannas. New seedlings do not appear at all tree-like and resemble a dark green fountain of needles. This form is called the grass stage. During this stage, which lasts for 5–12 years, vertical growth is very slow, and the tree may take a number of years simply to grow ankle-high. After that it makes a growth spurt, especially if there is no tree canopy above it. In the grass stage, it is very resistant to grass fires, which burn off the ends of the needles, but the fire cannot penetrate the tightly-packed needle bases to reach the bud. While relatively immune to fire, at this stage, the plant is quite appealing to feral pigs, and the early settlers' habit of releasing swine into the woodlands to feed was greatly responsible for the decline of the species. Longleaf pine forests are rich in biodiversity. They are well-documented for their high levels of plant diversity, in groups including sedges, grasses, carnivorous plants and orchids.〔Peet, R. K. and D. J Allard. 1993. Longleaf pine vegetation of the southern Atlantic and eastern Gulf coast regions: a preliminary classification. pp. 45–81. In S. M. Hermann (ed.) Proceedings of the Tall Timbers Fire Ecology Conference. No. 18. The Longleaf Pine Ecosystem: Ecology, Restoration, and Management. Florida: Tall Timbers Research Station.〕〔Keddy, P.A., L. Smith, D.R. Campbell, M. Clark and G. Montz. 2006. Patterns of herbaceous plant diversity in southeastern Louisiana pine savannas. Applied Vegetation Science 9:17-26.〕 These forests also provide habitat for gopher tortoises, which, as keystone species, dig burrows that provide habitat for hundreds of other species of animals. The red-cockaded woodpecker is dependent on mature pine forests and is now endangered as a result of this decline. Longleaf pine seeds are large and nutritious, forming a significant food source for birds (notably the brown-headed nuthatch) and other wildlife. There are 9 salamander species and 26 frog species that are characteristic of pine savannas, along with 56 species of reptiles, 13 of which could be considered specialists on this habitat.〔Means, D. Bruce. 2006. Vertebrate faunal diversity in longleaf pine savannas. Pages 155-213 in S. Jose, E. Jokela and D. Miller (eds.) Longleaf Pine Ecosystems: Ecology, Management and Restoration. Springer, New York. xii + 438 pp.〕 The Red Hills Region of Florida and Georgia is home to some of the best preserved stands of longleaf pine. These forests have been burned regularly for many decades to encourage bobwhite quail habitat in private hunting plantations. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Pinus palustris」の詳細全文を読む スポンサード リンク
|