What is a redwood?

(Li Jianwen)

Scientific name: Sequoia (Lamb. )Endl。 Also known as the world master. Cetaceans, sequoias. Evergreen, with a height of 1 10 m and a DBH of 8 m, is one of the largest trees in the world. Bark is reddish brown, longitudinally split and thick 15 ~ 25cm. Winter buds are sharp and scaly. Leaf type ⅱ, spirally inserted, the main branches and leaves are oval and oblong, about 6 mm long; The leaves of lateral branches are strip-shaped, 8 ~ 20 mm long, twisted at the base, arranged in two rows, sessile, with obvious midvein. Monoecious, male cone solitary branch apex or leaf axil; Female flowers are born at the top of short branches. The cone is oval, 2 ~ 2.5 cm long, 1.2 ~ 1.5 cm in diameter and reddish brown; Seed scale 15 ~ 20, mature in that year; The seed scale is attached spirally, woody and shield-shaped, and the developed seed scale has 2 ~ 5 seeds. The seed is ovoid, 4 ~ 6 mm long, brown, with wings on both sides and 2 cotyledons. Flowering period 1 1 to March of the following year, and cones mature in September. After 10 months, the cones cracked and the seeds scattered. Originated in a narrow area on the west coast of the United States, it is 720 kilometers long and 8-56 kilometers wide from southern Oregon to central California. Born at an altitude of 30 ~ 1000 meters, it often forms a pure forest on wet valley alluvial soil. Wood heartwood is red, sapwood is yellow and white, light and soft, easy to split, easy to process and resistant to decay. Wood is widely used in furniture, joinery, architecture, sleepers, poles, pipes, boxes and other materials. Introduced and cultivated in China, Shanghai, Nanjing and Kunming, it grows well.

North American forestry

(Forestry in North America)

(Hu Guyue)

The forest area in North America is 630 million hectares, the forest coverage rate is 34%, and the closed forest stock is 39.4 billion cubic meters. Among the forest areas, there are 400 million hectares of coniferous forests and 230 million hectares of broad-leaved forests.

Forest distribution

Coniferous forests in North America are distributed in most areas of Alaska and Labrador Peninsula in the United States, as well as vast areas connecting the two peninsulas. It extends far eastward, along the western Pacific coast, especially along the coastal mountains to Central America, and along the Atlantic coastal plain to the Gulf of Mexico in the east. Coniferous forests from Alaska to California are mainly composed of Larix principis-rupprechtii, Pinus brevifolia, Abies occidentalis, Pinus ponderosa and Pinus ponderosa, while central Canada is composed of spruce, Larix gmelinii and Pinus brevifolia. Coniferous forests in eastern Ontario, Quebec and Newfoundland are mainly composed of cone pine, resin pine and hemlock. The east coast is north of 42 degrees north latitude and consists of Douglas fir. North of latitude 52, it consists of Sitka spruce, hemlock and Nutt cobber. Mixed coniferous and broad-leaved forests are widely distributed in the Great Lakes region, the northeastern United States, New England and the Appalachian Mountains. In the mixed forest, conifers in the southeast are Pinus densiflora and Pinus virginiana, and conifers in the northwest are Pinus strobilus, Pinus rosin and Tsuga canadensis. Broad-leaved trees are mainly oak trees. Broad-leaved forests extend from the south of the Great Lakes to the Appalachian Mountains, and are widely distributed in the Mississippi River basin and the lowlands along the Atlantic Ocean. Broad-leaved forests are concentrated on the plateau from central New Jersey to the Mississippi River basin.

forest administration/management

Forests in North America were destroyed late, so a large area of natural forests was preserved. In the early stage of forestry development, it was simply to cut down and use wood. Canada/KLOC-Before the middle of the 0/9th century, in order to develop industry and agriculture, build towns and cut down forests on a large scale, forest management was simply to produce wood, so coniferous forests in southern and coastal areas were cut down in large quantities. The United States began with European immigrants, and by the end of 19, forests were only cut down and not renewed. In the process of large-scale immigration reclamation, China has cut down 65.438+300 million hectares of natural forests. Subsequently, it tends to pay equal attention to logging and afforestation. At the end of 19, Canada began to attach importance to forest management while logging, but during 1900 ~ 1960, the average annual afforestation area was only 5600 hectares. As early as 1873, the United States passed the first law on forestry-the Tree Planting Law. 189 1 The establishment of the state-owned forest management system marks the official start of the national forest protection movement and promotes the rapid development of forestry.

Now, forestry pays attention to the multiple benefits of forests. Since the 1960s, Canada has clearly stipulated that forest management is mainly based on the following purposes: (1) giving play to the multiple benefits of forests; (2) Improving forest productivity through stand transformation and regeneration; (3) Ensure the future production of certain specifications and varieties of wood; ④ Supply a certain amount of wood to the existing wood processing enterprises. 1968 started the continuous inventory of national forest resources, and investigated the changes of forest resources through satellites. Since the 1960s, the afforestation area has expanded rapidly, and a plan named "Design Forest" has been formulated, which implements the unified management of silviculture and forest industry. In the United States, in 1960, Congress passed the Multi-purpose Sustainable Logging Law of State-owned Forests, clearly stipulating that the management objectives of state-owned forests are recreation, grazing, timber production, water harvesting protection and wildlife habitat. Since 1970s, the annual afforestation area is 700,000-800,000 hectares. Attach importance to scientific afforestation, tree species improvement and intensive management level improvement, advocate the creation of "high-yield forests", create "third forests" in 13 southern States, continuously inventory forest resources with advanced technology, and carry out large-scale forest protection, fire prevention and pest control.

forestry

In this century, North America is still one of the largest export areas of wood and forest products in the world. In the early 1980s, Canada and the United States cut 5.4 billion cubic meters of wood every year, accounting for 18% of the world's total output. The output of wood-based panels is 262.85 million cubic meters, accounting for 28% of the world's total output; The output of paper and pulp is1.300 million tons, accounting for 45% of the world's total output. In 1970s, the volume of forest products exported by Canada and the United States to the world was about 73-75 million cubic meters, mainly exported to Europe and Japan.

Forestry education and scientific research Forestry colleges not only attach importance to the cultivation of forestry professionals, but also have their own scientific research strength and equipment. Forestry education, there are more than 50 forestry colleges and departments in American comprehensive universities. There are also many two-year short-term universities with a complete curriculum system. Forestry scientific research has been widely valued by the state and society. Both the government and large forestry companies have forestry research institutions. Managing forestry scientific research is the main task of the forestry departments in Canada and the United States, especially the basic task of the Forestry Bureau of the Federal Ministry of Environment in Canada. Through scientific research, coordinate principles and policies to promote forestry development. See Canadian Forestry and American Forestry.