1 general situation of ecological barrier area in Three Gorges Reservoir Area
Ecological barrier zone in the Three Gorges Reservoir Area refers to the Yangtze River Three Gorges reservoir submerged land line (in front of the dam normal water level is 175m with a 5 year flood in November and 5 years from the backwater surface line) to the first mountain ridge area, according to the requirements of ecological functions, the barrier is divided into 2 parts, one is the ecological protection zone that refers to the region along the line above the horizontal projection of 100m wide base land requisition is two weeks, by ecological zone, ecological protection zone refers to cities and towns and regions. Rural urban migration and emigration of Three Gorges Reservoir Area Resettlement and other reasons, the current regional population density as high as 888 - /km, is 6.6 times the country; due to the immigration resettlement, resulting in deforestation, steep grain and other phenomena occur, resulting in the serious destruction of forest vegetation, according to the latest survey by remote sensing the Three Gorges Reservoir area data, soil erosion area is 29 thousand and 600 - km, the total land area of 51%, the area of moderate loss total loss area according to the 82.5%. of the Three Gorges Project of ecological and environmental monitoring over the years, the overall ecological environment in Three Gorges Reservoir area is a fragile ecological area, the forest coverage rate is low, only 23.1%, and the uneven distribution of 10%[3]. along the sides of the ecological environmental protection has reached a very urgent situation.
2 status of land use in the ecological barrier area of the Three Gorges Reservoir Area in Zigui County
According to the Zigui county two inventory data, ecological barrier zone of Three Gorges Reservoir Area in Zigui County town of Jiuwanxi, Qu Yuan involving a total of 9 towns, an area of 46 012.2hm - 253.92hm -, which accounted for 0.55%; paddy field, dry land - 5780 HM, accounting for 12.56%; 9 - 508.23hm yuan, accounting for 20.66%; 26 694.23hm - Woodland 1 024.00hm, accounting for 58.02%; the grass - land, accounting for 2.23%, other 2 - 751.48hm, accounting for 5.98% of Table 1 forest area is the largest, followed by the garden and dry land. 13 - 978.55hm forest woodland, shrub forest land accounted for 30.38%, accounting for 15.61%, 7181.06 HM -, 5 534.63hm - other woodland, woodland accounted for 5.98%, the other including woodland and forest. The garden is mainly citrus orchards and tea garden, the main dryland sloping farmland. Other land including road land, water conservancy construction land and urban construction and industrial and mining land, etc.. The important ecological protection of the Three Gorges Reservoir area is forest land, garden land, dry land and other land. Due to the frequent, easy to cause soil erosion, it is an important risk for the safe operation of the Three Gorges project, and also the key construction area of vegetation restoration in the Three Gorges Reservoir Area.
3 vegetation restoration in ecological barrier zone
3.1 guiding ideology
In order to protect the ecological environment of the Three Gorges reservoir, to improve the ecological environment construction and protection system, protect the ecological environment, protect the ecological environment and ensure the sustainable development of the Three Gorges Reservoir area, improve the living conditions of the Three Gorges reservoir.
3.2 tree species selection
According to the principle of ecological construction and suitable tree, the selection of tree species should be based on native species, and the species with high growth speed, stable growth, strong resistance and high economic value. With exotic species, need to introduce foreign species, should choose the introduction test successful species. According to the different geographical conditions in the working area, site conditions, stand conditions, and construction content, selection of biology and ecology, forestry characteristics suitable for the site conditions, stand conditions and good adaptability and strong resistance and fast growth of tree species. Selection of species for Liquidambarformosana, Cupressus funebris, Liquidambar cypress, Cinnamomum camphora, Zhang privet Ligustrumlucidum Osmanthusfragrans, Koelreuteria paniculata, osmanthus Koelreuteria Erio-botryajaponica loquat native tree species, which can guarantee the demand of ecological protection can meet the requirements to beautify the environment.
3.3 vegetation restoration technology
In order to enhance forest protection, we must increase the forest area and improve forest quality. Vegetation ecological barrier zone in Zigui County of Three Gorges reservoir mainly to restore the ecological public welfare forest afforestation, inefficient ecological forest rehabilitation and closing off other 3 vegetation restoration measures. Through the forestation in the forest, returning farmland to forest, can effectively increase the forest coverage rate; transformation of low quality forest, can effectively improve the quality of the stand; take measures to promote forest afforestation and improve forest quality.
Garden land, dry land, grassland, shrub and other woodland and other large areas, a wide range of distribution, can increase the forest area by artificial afforestation, improve forest protection. As part of a larger distribution area of Masson pine forest Pinus massoniana and Rob-inia pseudoacacia of coniferous forest of Robinia pseudoacacia plantation, due to pest damage and aging forest stand quality decline, fallen dead wood, wood rot disease is more, the canopy density was reduced, seriously affect the normal function of forest protection. This part of the forest land can be transformed by means of the way to remove the disease, replacement of tree species, promote forest regeneration, so that the restoration of forest ecological function. While some woodland and shrub land cultivating future by way of afforestation, the forest forest, and improve the quality of forest.
3.3.1 afforestation of ecological public welfare forest
(1) applies to the category: mainly for non forest land, forest land, garden land, dry land, grassland and some shrub land.
(2) cleaning: clean the forest by planting holes or massive clean-up, land clearing and preparation can be performed at the same time. When cleaning up to remove weeds and shrubs around the planting hole as the center, cleaning is generally in the range of 80cm * 80cm. attention to the removal of harmful forestry plants, serious area to reduce the rodent population density of rats, and afforestation. Forest land clearing should be appropriate to retain the original broad-leaved tree species.
(3) preparation: the afforestation with holes preparation, water conservation forest and soil conservation forest specifications for 50cm * 50cm * 40cm, scenic forest specifications for 80cm * 80cm * 80cm., sooner rather than later, usually in the autumn and winter. Early preparation can make the soil fully ripening, is beneficial to improve the survival rate of seedlings growth.
(4): to build the afforestation mode of mixed forest, soil and water conservation forest and water conservation forest in privet, cedar, Feng Xiang, Robinia pseudoacacia and Koelreuteria paniculata species such as mixed conifer and broadleaved forest and broad-leaved forest, mixed ratio of 5: 5 or 6: 4, can take the planting or mixed strains. In the scenic forest of osmanthus, loquat, camphor, Koelreuteria paniculata species such as broad-leaved mixed forest to create outstanding landscape effect, can take the planting or bulk mixed mode.
(5): planting density of planting density is determined according to the different forest types and tree species. The planting density of soil and water conservation forest is 2m * 3M, the planting density of water conservation forest is 2m * 2m, and the planting density of landscape forest is 3M * 4m.
(6) afforestation time: in the winter and spring season as the main afforestation season, generally in November ~ April years of afforestation, should be appropriate to avoid early spring drought, can improve the survival rate of afforestation.
(7) seedling treatment and planting: planting seedlings to 2~3 years, the main selection of seedlings and cutting seedlings, growth is good, the development of normal, no insect pest. Before afforestation can be appropriate treatment of seedlings, seedling planting before the root system can be dipped in dilute appropriate mud. When necessary, may be appropriate to cut off part of the foliage. For the development of the injured roots, abnormal partial root, cutting short long taproot and lateral root, can proper pruning.
When planting seedlings seedling stem to vertical root to stretch to the appropriate depth, filling half after seedling compacted, then fill compacted, finally cover the soil. After planting seedlings, the seedlings should be poured out to ensure the survival of the water, in the dry season, depending on the circumstances need to be properly watered.
Transformation of 3.3.2 low efficiency ecological public welfare forest
(1) transformation object: suitable for forest pest damage, serious aging, single species, protection of ecological forest and low canopy density lower woodland.
(2) the reform measures: the transformation of the ecological forest, mainly to take the repair and planting and thinning of the planting, etc.. For forest canopy closure in 0.5 following the restoration of inefficient replanting measures in the woodlands and open the appropriate thinning after cleaning for replanting the tree species. The canopy above 0.7 species, pure, growth retardation, serious diseases and insect pests, protection function of ecological forest thinning by replanting method. The cutting of dry rot, wood, pressed wood, the shade density was adjusted to 0.4~0.5, and then planting tree species. Planting trees mainly privet, cypress, maple, Koelreuteria paniculata and other native species.
(3) the transformation requirements: clean up the replanting hole cleaning, cleaning is generally in the range of 80cm * 80cm. with soil holes preparation, general specification for 50cm * 50cm * 40cm. configuration by planting, planting the glyph mixed etc.. Transformation of the filling time in winter, spring season. Seedling treatment and cultivation methods and artificial afforestation of ecological public welfare forest.
3.3.3 afforestation
(1) enclosed object: suitable for tree growth situation is relatively good, the overall stand age is small, with low canopy density but with strong resilience, woodland and shrub land and forest land.
(2) enclosure: according to the different purposes and conditions can be taken full closure, closing hillsides and semi closed three way round. In the woodland, shrub canopy density is less than 0.2 and has strong self recovery capacity of forest on the implementation of full closure; growth in good, high canopy density, have certain human activities have on the implementation of semi closed woodland and round seal.
(3) the closure years: the closure of the closure and the closure of the area under the conditions of the closure of the area, and the closure of the full closure period of 10~15 years.
(4) enclosure operation measures: space enclosed lots of woodland, forest and forest replanting measures to implement the closure, the main planting of Ligustrum lucidum, Liquidambar formosana, Koelreuteria paniculata, cypress and other native species, the formation of mixed conifer or broadleaf mixed forest with existing species. The main methods of massive replanting replanting, under the canopy of replanting, forest planting, vacant land. Seedling cultivation method and artificial afforestation of ecological public welfare forest. In a natural regeneration capacity of forest, planting trees around the fallen dead wood, wood rot, shrubs, weeds and other artificial removal, in order to promote natural regeneration. In the closed area of the main road traffic or other human activities in many area, build up a solid afforestation billboards or signs, indicate the name and enclosure area in administrative areas, four borders, fencing area, fencing, fencing, fencing, Guan Hu responsible person. People in livestockactivities area but also set up a ranger station, fencing, digging ditches, especially to prevent illegal phenomenon.
(5) enclosure protection: full closure activities, in afforestation, forest land is absolutely forbidden to feel, brush, grazing, pruning, mining, picking up litter, turpentine, and Wa Shugen were digging herbs all human activities.
Half way for the seasonal breeding of letters in the annual 3~10 month closing hillsides to facilitate afforestation, forest growth season forbidding. During prohibition, the prohibition of all human activities, the rest of the season can be organized into the wood, grass, Bush, but prohibited deforestation to protect trees, seedlings and saplings. Round letters for education in order to achieve in sealed enclosure forest.
According to the needs of the local people's production and life, the enclosure conditions where the area turns banned in grazing and cutting area, can effectively organize the masses to cut, grazing, but prohibit the felling of timber trees and saplings.
3.4 Late tending
Refers to the use of Forest Tending Felling around fostering target take silvicultural measures after the forest canopy. Its purpose and function is to adjust tree species composition and stand density, balance soil nutrient and water cycle, improve the ecological conditions of forest growth, shorten the period of forest cultivation, improve the quality and process value, and play a variety of functions.
Afforestation should be completed after 3 years of continuous tending, each tending 1~2 times, including weeding, scarification, cutting, pruning, planting, pest control etc.. Afforestation, which is not qualified for afforestation, is to be repaired or re planted in time. The planting planting age seedlings should be used. The occurrence of diseases and insect pests, as soon as possible to prevent, discover, timely control. At the same time, pay attention to the prevention of human and livestock damage seedlings, the timely discovery and control of fire, preventing forest fires.
The new forest was 9~10 implementation of a weeding in afforestation around the pit, second years all the time in the spring and summer weeding. Should be in the light of deep scarification, not to hurt the root depth, generally 5~10cm. in understory vegetation growth, and tree growth to compete, affecting growth and seedling tree species in the forest update. Through artificial way remove the growth of trees shrubs, vines and shrubs to exclude weeds, water, fertilizer, light and heat competition, promote seedling growth. Brush in general the most vigorous growth season of vegetation tending, the beginning of 6, before the end of the end of the 7.
The main adverse natural pruning pruning in the forest, poor ventilation and light in. Generally take the flat cut method, focus on the branches, dead branches over the forest. Young forest tree pruning height not more than 1/3 of high and middle age forest tree height not more than 1/2. the timely removal of dying trees and the dead wood.