Research on the genesis and ecological restoration technology of pecan low-yield forest

Research on the genesis and ecological restoration technology of pecan low-yield forest

Cheng Zhong

Carya cathayensis Sarg is a unique woody oilseed tree species and a famous dried fruit tree economic tree species in China, mainly distributed in Lin'an, Anji, Ningguo, Jixi and other counties and cities in the Tianmu Mountains. As a unique regional economic forest, it has formed a considerable scale of operation, with dozens of registered trademarks on products, and some brands are also bright in the international market. However, there are many problems in the industrialization process of pecans, such as the low degree of good seeding, the original stand tree body is tall and the crown width is small, fruit harvesting is difficult, soil degradation, soil erosion is serious, and disease and insect harm are serious. In Jixi County, Anhui Province, pecans are mainly distributed in Jingzhou, Jiapeng, Fuling and other townships, in the past 10 years, the area of hickory forests has increased by more than 1 times, the output has increased by 2.6 times, and the output value of the primary industry has gradually increased from 42.6 million yuan in 2003 to about 125.9 million yuan.

1 Types and characteristics of pecan low-yielding forests

1.1 Aging stands

This kind of forest stand has become a forest in the planned economy period, the age of the tree is more than 50 a, the total area of the forest stand is 630 hm 2, mainly distributed in Jingzhou, Xiaoyao, Yonglai, Dachang and other places. The characteristics of the forest stand are due to extensive management, high density, narrow canopy, subgrong height accounting for about 1/2, serious pests and diseases and difficult to control, low and unstable fruit yield, and obvious large and small annual phenomena.

1.2 Improperly managed plantations

Due to the lack of experience in high-yield cultivation technology, there are many problems in terms of suitable land for trees, good seeds and strong seedlings, afforestation technology and care management. The forest stand is characterized by high density, serious soil erosion, serious pests and diseases, and a large ratio of trees to diameter.

1.3 Stand formed by transformation of secondary mixed forests

This type of forest stand is formed by the transformation of secondary forests dominated by pecans. One type is a mixed forest of pecans with good forest stand structure× yuan mixed bamboo, mainly distributed in villages such as Xiaoyao, Yonglai and Daqiao. This type of stand has a good structure, relatively good economic benefits and stability, but the density is large, the crown height/tree height value is small, and it is difficult to apply, prune and harvest the fruit. Another type is the secondary forest formed by natural subspecies (animal and rat transport transmission), which is artificially cut down and shrubned for the purpose of managing pecans, and the age and density of trees are uneven or artificially replanted into large seedlings.

1.4 Artificial young and middle forests

This type of forest stand is a pure forest of young and middle-aged forests formed by the implementation of project afforestation, returning farmland to forests and other projects, which are distributed in all townships and towns in Jixi County, and the total area of Jixi County is about 3 360 hm 2. The management of such forest stands and forest farmers is relatively fine, but most of them are "lawless", with few intercropping and diligent weeding, resulting in serious soil erosion. Improper use of pesticides and chemical fertilizers leads to serious occurrences of soil acidification, rotten skin disease, root rot and so on. Although the density of standing wood is uniform, it is generally large, resulting in the length of some trees, poor ventilation and light transmission, delayed fruiting, and dry rot and rotten skin disease are particularly serious.

2 Technical measures and effects of ecological restoration of pecan low-yield forests

2.1 Canopy regulation and restoration

Adjust the shape, uniformity and light transmittance of the canopy through reasonable pruning; resolutely cut down the weak and pressed trees with a seriously imbalanced crown height/tree height ratio in the dense forest stand; appropriately shorten the main branches of the long branches that enter the fruiting period; and implement top plucking after the young trees grow to a certain height, pull the side branches cable-stayed, and cultivate dwarfed broad-ovate crowns. Pay attention to protecting the saw, shear and "fresh" places, you can use the hydraulic gun to spray wax "sealing" or spray imitation coating agent or apply 5 to 10 times of vinyniacin liquid to protect the "wound".

2.2 Restoration of woodland vegetation

Slopes above 25° to eliminate reclamation and excavation, forest fertilization and application can be combined with the field about 1.5 m from the tree base of the external radial or circular trenching and burial, or along the contour line "bamboo knot" trench burial. Every year, the pecans can be cut once a year before harvesting. For slopes below 25 ° of afforestation land, beans, peanuts, etc. can be intercropped within 3 to 5 a to cultivate (eliminate intercropping sesame seeds). After stopping intercropping, and along the contour line horizontally planted purple locust, green ash leaf beads, "five grain trees" and other shrub belts (each height difference of about 10 m planting a belt), and then use cutting and irrigation to bury green as green manure and intercept runoff.

2.3 Scientific fertilization

The first is soil testing and fertilization. Coarse (fine) bone flatstone soils formed by the development of limestone, conglomerate, slate, etc., are relatively rich in mineral elements, which can basically meet the normal growth needs of pecans. Therefore, some nitrogen and organic fertilizers can be applied in moderation before fruiting. Applying some boron fertilizer in the fruiting period can improve the fruit set rate and reduce the fruit drop rate. The rough bone hempstone soil formed by granite weathering has a small pH value, heavy sandiness and low fertility, and an appropriate amount of potassium fertilizer, calcium, magnesium and phosphorus fertilizer should be applied. The second is to spray the fertile fruit fertilizer of the fruit. At the beginning of April, canopy spray urea + KH2 PO 4 + hundred insecticidal formula medicinal fertilizer once to kill insecticidal flowers; in mid-April, female flowers bloom, spray boron fertilizer (or agricultural rare earth) + KH 2 PO 4 + urea formula once, and re-spray once around May 20 to benefit pregnant fruits and reduce fruit fall.

2.4 Pest control

There are many kinds of pecan pests, the main pests and diseases are hickory aphids, bud maggots, tianniu, rotten skin disease, etc., which have the greatest impact on the quality and yield of pedigree pedigree. The control of insect pests is carried out by trunk injection, woodland spraying, canopy spray, and interforestary application of tobacco agents, which are targeted for individual control or a combination of several methods. Booby-trap moths with a frequency vibration insecticidal lamp/10,000 m2 is a cost-effective control method. After digging up the nest to kill the ants, combined with spraying the ant killer to control termites and so on. It is forbidden to use organophosphorus organochlorine pesticides with large inhalation or residues such as oxylecon and furandan. Disease prevention and control is mainly based on prevention. Improve the ventilation and light transmission environment in the forest, combined with harvesting fruit to cut and burn diseased branches, dead branches, and insect branches. Spray stone sulfur compound to control branch diseases before the sap flows but does not germinate. When the new leaves are just unfolded and shaped, they spray aspirant thiophetam. For the trunk rot disease, ulcer disease, black water disease that has occurred, it can be prevented and controlled by applying 5 to 10 times Guixing, Ruipu 2000, tetramycin, 3 to 5 ° Bé stone sulfur compound after scraping the diseased part. Canopy spray tetramycin can control a variety of diseases.

3 Discussion

The ecological restoration of pecan low-yield forests is essentially the comprehensive application of forestry technical measures such as density and canopy regulation, soil cover restoration, formula (soil testing) fertilization, improvement of soil fertilization capacity and pollution-free comprehensive control of pests and diseases, etc. Based on the ecological safety, food safety and high-quality stable yield of fruit forests, each technical link should be integrated into the ecological elements.

(1) Combining density adjustment with pruning regulation to repair the canopy is the basis for the high-quality and abundant production of pecans. Adult pecan forest separations should be around 300 plants/hm2, maintaining a depression of about 85%, the canopy is intersected with each other≤ 8% of the triangular broad ovate canopy.

(2) Planting grass under the hickory forest to restore vegetation is the premise of stable and productive production. The planting of white clover and baixi grass under the forest increases the soil nutrient content of the woodland, reduces the temperature in the summer forest stand, increases the interception coefficient, and reduces the runoff, forming an ecological economic forest.

(3) Scientific fertilization is a direct measure to increase the yield of pecans. The special fertilizer of soil testing formula combined with extra-root spraying to protect flowers and fruit fertilizers has a remarkable effect on increasing yield, which is 3 times higher than that of single application of urea + compound fertilizer (control).

(4) Timely control of pests and diseases is the guarantee of fruitful pecans. In pest control, the use of pollution-free biopesticides is advocated, and the use of organophosphorus and organochlorine pesticides with systemic or high residues is eliminated.