阅读说明：本技术 一种以水源涵养功能为主导的桉树混交林改造方法 (Eucalyptus mixed forest transformation method taking water source conservation function as leading factor ) 是由 宋贤冲 唐健 覃祚玉 石媛媛 赵隽宇 曹继钊 王会利 覃其云 邓小军 潘波 蒋湖 于 2021-09-03 设计创作，主要内容包括：本发明提供了一种以水源涵养功能为主导的桉树混交林改造方法,属于生态修复技术领域。该方法包括以下技术步骤：林地选择、林木择伐、整地挖穴、苗木种植、苗木抚育、林木管理。本发明方法能够有效改进林分结构,改良林分土壤,有效提高林分蓄积量,促进林分自然更新,增加林分的结构复杂性,保护林下植被多样性,推动林下环境与土壤多样性组成及其食物网关系的自然恢复,加快桉树人工林水源涵养功能恢复,成本低,成效高。(The invention provides a method for modifying eucalyptus mixed forest by taking water conservation function as a leading factor, belonging to the technical field of ecological restoration. The method comprises the following technical steps: selecting forest land, cutting forest trees selectively, digging holes in the soil, planting nursery stocks, tending the nursery stocks and managing the forest trees. The method can effectively improve the structure of the forest stand, improve the soil of the forest stand, effectively improve the storage amount of the forest stand, promote the natural updating of the forest stand, increase the structural complexity of the forest stand, protect the diversity of the vegetation under the forest, promote the natural recovery of the diversity composition of the environment and the soil and the food net relationship of the environment and the soil under the forest, accelerate the recovery of the water conservation function of the eucalyptus artificial forest, and has low cost and high effect.)

1. A eucalyptus mixed forest transformation method taking a water conservation function as a leading factor is characterized by comprising the following steps:

(1) selecting a forest land: the soil condition of the transformed eucalyptus pure forest is more than moderate, the age is between 4 and 6 years, the individual diameter grade of the trees is obviously differentiated, and the dominant trees can be obviously distinguished, wherein the number of the dominant trees is 150 plus trees/hectare;

(2) forest selective cutting: the method comprises the steps of retaining eucalyptus which is good in growth vigor, luxuriant in leaves and strong in vitality, cutting the endangered and dead trees which are prone to plant diseases and insect pests, have backward growth and smaller diameter grade and low-yield and inferior eucalyptus, and retaining 30-45 plants/mu of eucalyptus after cutting;

(3) land preparation and hole digging: carrying out corrosion promotion on the eucalyptus duvet after selective cutting, preparing soil by adopting a non-hardening treatment method, retaining residues after selective cutting of forest lands, simultaneously manually cleaning weeds, applying a herbicide, and then excavating planting holes;

(4) planting the nursery stock: after weathering, applying base fertilizer to the dug planting holes, applying 200-300g of compound fertilizer to each planting hole, selecting more than 2-year-old seedlings of the local precious tree species, and carrying out artificial seedling planting in a period of sufficient water in the forest land from 4 months to 5 months when the seedlings are required to grow well and have developed root systems and no plant diseases and insect pests;

(5) nursery stock tending: tending is carried out at 6 months in the current year of planting the seedlings of the local precious tree species, and the tending is continuously carried out for 4-5 years;

(6) managing the forest trees: when nursing precious trees in the local soil, attention is paid to protecting the trees, diseases and insect pests, damage to people and livestock and forest fire are prevented, and grazing and firewood production interference are forbidden.

2. The method for improving the eucalyptus hybrid forest with the water conservation function as the main component in claim 1, wherein in the step (4), the local precious tree species are any two or three combinations of old rice, grifola frondosa and quercus robur.

3. The method for improving the eucalyptus mixed forest with the water conservation function as the main factor in claim 2, wherein in the step (4), the mixed ratio of the valuable tree species in the countryside is 1:1 or 1:1: 1.

4. The method for improving the eucalyptus mixed forest with the water conservation function as the main factor in claim 1, wherein in the step (4), the ratio of the number of the plants of the eucalyptus after the cutting to the number of the plants of the local valuable tree species is 1: 1-2.

5. The method for improving the eucalyptus hybrid forest with the water conservation function as the main factor in claim 1, wherein in the step (4), the row spacing of the local precious tree species is 2-3m, and the line spacing is 3-4 m.

6. The method for improving the eucalyptus mixed forest with the water conservation function as the main factor in claim 1, wherein in the step (5), the nursery mode of the seedlings of the local precious tree species is as follows:

tending in the first year: tending the seedlings in 6 months of the year, taking the seedlings as centers, shoveling grass within the radius of 1-2cm, expanding planting holes to 45-50cm, simultaneously performing topdressing, applying 20-30g of organic fertilizer to each planting hole, investigating the survival rate of the seedlings, and timely replanting dead seedlings;

tending in the second year: tending is carried out in 5-6 months of the next year of seedling planting, grass shoveling is carried out within the radius of 5-10cm by taking the seedling as the center, planting holes are enlarged to 60-70cm, additional fertilization is carried out simultaneously, 10-20g of potassium sulfate compound fertilizer is applied to each planting hole, and grass shoveling is carried out once again after 9-10 months;

tending in the third year: tending the seedlings in 6-7 months in the third year, shoveling the grass in the range of 20-30cm in radius by taking the seedlings as the center, enlarging planting holes to 75-90cm, simultaneously performing topdressing, and applying 20-30g of potassium sulfate compound fertilizer to each planting hole;

tending in the fourth year: tending the seedlings in 7-8 months in the fourth year, shoveling grass within the radius of 40-50cm by taking the seedlings as the center, shoveling grass once again in 9-10 months, and pruning and shaping;

tending in the fifth year: tending the seedlings in the fifth year of 9-10 months, shoveling grass in the radius range of 60-80cm by taking the seedlings as the center, pruning and shaping, and selectively cutting the dying trees, the pressed trees and the dead trees.

7. The method for improving the eucalyptus hybrid forest with the water conservation function as the main factor, as recited in claim 6, wherein in the step (5), the pruning and shaping are performed to prune the branches of the nursery stock which are less than 1.7 meters from the ground, then the pruned branches are decomposed into branch segments with the length of 10-20cm, and then the branch segments are evenly and flatly paved on the forest land.

8. The method for improving the eucalyptus hybrid forest with the water conservation function as the main factor in claim 7, wherein in the step (5), the method for pruning and shaping comprises the following steps: selecting a branch to be repaired, sawing the branch close to the base of the branch, sawing the lower part of the branch firstly, and then sawing the upper part of the branch to ensure that the cut is parallel to the trunk of the seedling.

9. The method for improving the eucalyptus hybrid forest with the water conservation function as the main component as claimed in claim 1, wherein in the step (3), the planting hole specification is (30-40) cm x (30-45) cm.

Technical Field

The invention belongs to the technical field of ecological restoration, and particularly relates to a method for modifying eucalyptus mixed forests by taking a water source conservation function as a leading factor.

Background

At present, large-area eucalyptus artificial forests exist in south China, and with the annual expansion of the area of the eucalyptus artificial forests, the increase of operation intensity and the simplification of forest stand structures, ecological negative effects such as land fertility decline, forest stand degeneration, the lack of diversity of vegetation under the forest, the frequent occurrence of diseases and insect pests and the like are increasingly displayed, so that the ecological function of the eucalyptus artificial forests is low in value or the water source conservation function of the artificial forests is lost, and the ecological stability of the eucalyptus artificial forests is seriously threatened.

The prior art has a method for transforming eucalyptus artificial forests, for example, the publication No. CN 110169298A discloses a method for ecologically cultivating eucalyptus by cooperating wood production with other ecosystem services, the method comprises mixing eucalyptus with precious tree species such as Tasmanian Bluegum and Tamarindus indica to plant forest, wherein the eucalyptus is short-period operation tree species, the precious tree species is long-period operation tree species, the method can foster and fell eucalyptus and intermediate fell precious tree species, can maintain the wood production capacity of eucalyptus artificial forests, however, due to the lack of long-term tending of precious tree species and the shortage of felling of eucalyptus and intermediate felling of precious tree species, the survival rate of precious tree species is low, the forest stand is simple in structure and low in biodiversity, large-scale felling and intermediate felling of eucalyptus have great loss on forest ecosystem function and ecological restoration, and rapid restoration of water source conservation function of eucalyptus artificial forests cannot be achieved.

Therefore, there is a need to provide a method for improving eucalyptus mixed forest which is dominated by water conservation function, so as to promote the growth of trees, increase the structural complexity of forest stand, effectively protect biological diversity, maintain land capability and quickly recover water conservation function.

Disclosure of Invention

Aiming at the problems, the invention provides a eucalyptus mixed forest reconstruction method taking a water source conservation function as a main factor, which can effectively improve forest stand structure, improve forest stand soil, effectively improve forest stand accumulation amount, promote natural update of forest stands, increase structural complexity of forest stands, protect vegetation diversity under the forest, promote natural recovery of diversity composition of under-forest environment and soil and food net relationship thereof, accelerate water source conservation function recovery of eucalyptus artificial forests, and has low cost and high efficiency through a series of measures such as eucalyptus forest tree cutting selection, reasonable tree species matching, mixed ratio, nursery stock tending and the like.

The invention is realized by the following technical scheme:

a eucalyptus mixed forest transformation method taking a water source conservation function as a leading factor comprises the following steps:

(1) selecting a forest land: the soil condition of the transformed eucalyptus pure forest is more than moderate, the age is between 4 and 6 years, the individual diameter grade of the trees is obviously differentiated, and the dominant trees can be obviously distinguished, wherein the number of the dominant trees is 150 plus trees/hectare;

(2) forest selective cutting: the method comprises the steps of retaining eucalyptus which is good in growth vigor, luxuriant in leaves and strong in vitality, cutting the endangered and dead trees which are prone to plant diseases and insect pests, have backward growth and smaller diameter grade and low-yield and inferior eucalyptus, and retaining 30-45 plants/mu of eucalyptus after cutting;

(3) land preparation and hole digging: carrying out corrosion promotion on the eucalyptus duvet after selective cutting, preparing soil by adopting a non-hardening treatment method, retaining residues after selective cutting of forest lands, simultaneously manually cleaning weeds, applying a herbicide, and then excavating planting holes;

(4) planting the nursery stock: after weathering, applying base fertilizer to the dug planting holes, applying 200-300g of compound fertilizer to each planting hole, selecting more than 2-year-old seedlings of the local precious tree species, and carrying out artificial seedling planting in a period of sufficient water in the forest land from 4 months to 5 months when the seedlings are required to grow well and have developed root systems and no plant diseases and insect pests;

(5) nursery stock tending: tending is carried out at 6 months in the current year of planting the seedlings of the local precious tree species, and the tending is continuously carried out for 4-5 years;

(6) managing the forest trees: when nursing precious trees in the local soil, attention is paid to protecting the trees, diseases and insect pests, damage to people and livestock and forest fire are prevented, and grazing and firewood production interference are forbidden.

Preferably, in the step (4), the local precious tree species is any two or three of old rice, loguat and quercus robusta.

Preferably, in the step (4), the mixing ratio of the indigenous precious tree species is 1:1 or 1:1: 1.

Preferably, in the step (4), the ratio of the number of the strains of the eucalyptus after the cutting to the number of the strains of the local precious tree is 1: 1-2.

Preferably, in the step (4), the row spacing of the local precious tree species is 2-3m, and the line spacing is 3-4 m.

Preferably, in step (5), the tending method is:

tending in the first year: tending the seedlings in 6 months of the year, taking the seedlings as centers, shoveling grass within the radius of 1-2cm, expanding planting holes to 45-50cm, simultaneously performing topdressing, applying 20-30g of organic fertilizer to each planting hole, investigating the survival rate of the seedlings, and timely replanting dead seedlings;

tending in the second year: tending is carried out in 5-6 months of the next year of seedling planting, grass shoveling is carried out within the radius of 5-10cm by taking the seedling as the center, planting holes are enlarged to 60-70cm, additional fertilization is carried out simultaneously, 10-20g of potassium sulfate compound fertilizer is applied to each planting hole, and grass shoveling is carried out once again after 9-10 months;

tending in the third year: tending the seedlings in 6-7 months in the third year, shoveling the grass in the range of 20-30cm in radius by taking the seedlings as the center, enlarging planting holes to 75-90cm, simultaneously performing topdressing, and applying 20-30g of potassium sulfate compound fertilizer to each planting hole;

tending in the fourth year: tending the seedlings in 7-8 months in the fourth year, shoveling grass within the radius of 40-50cm by taking the seedlings as the center, shoveling grass once again in 9-10 months, and pruning and shaping;

tending in the fifth year: tending the seedlings in the fifth year of 9-10 months, shoveling grass in the radius range of 60-80cm by taking the seedlings as the center, pruning and shaping, and selectively cutting the dying trees, the pressed trees and the dead trees.

Preferably, in the step (5), the pruning and shaping are to prune the branches of the nursery stock which are less than 1.7 meters from the ground to the top, then decompose the pruned branches into branch sections with the length of 10-20cm, and then evenly and flatly pave the branch sections on the forest land.

Preferably, in the step (5), the pruning and shaping method includes: selecting a branch to be repaired, sawing the branch close to the base of the branch, sawing the lower part of the branch firstly, and then sawing the upper part of the branch to ensure that the cut is parallel to the trunk of the seedling.

Preferably, in the step (3), the planting hole is (30-40) cm x (30-45) cm.

Compared with the prior art, the invention has the advantages and beneficial effects that:

1. through a series of measures such as eucalyptus forest selective cutting, reasonable matching of tree species, mixed crossing proportion, nursery stock tending and the like, the structure of the forest stand can be effectively improved, the soil of the forest stand is improved, natural updating of the forest stand is promoted, the structural complexity of the forest stand is increased, the diversity of vegetation under the forest is protected, and natural recovery of the diversity composition of the environment under the forest and the soil and the food net relationship of the vegetation is promoted. Compared with the pure eucalyptus forest which is not modified, the surface runoff of the modified mixed forest is reduced by 27.83-44.24%, the forest stand accumulation is effectively improved, the restoration of the water conservation function of the eucalyptus artificial forest is accelerated, the modification cost is low, and the effect is high.

2. The method mixes eucalyptus with valuable tree species in the countryside for afforestation, increases the structural complexity of the forest stand, can effectively protect the biological diversity, quickly recover the water source conservation function, maintain the land fertility and promote the growth of the forest. The proportion of the collocation of the rural precious tree species and the plant number of the rural precious tree species and the eucalyptus is kept, so that a good inter-species competition relationship can be formed when the forest stand just enters the middle-age forest. The root systems of the tree species of the mixed forest are staggered, the ingredients are complex, the number of dry branches and fallen leaves is large, more substances can be provided for soil microorganisms, the soil fertility can be effectively improved, the physical and chemical properties of the soil can be obviously improved, the soil nutrients are activated, and the nutrient absorption of forest plants can be increased.

3. The method continuously nurses the seedlings of the local precious tree species for 4-5 years, and different nurturing measures are taken every year, so that the survival rate of the local precious tree species can be effectively improved, the loss of forest ecological system function and ecological restoration caused by large-scale selective cutting or thinning is avoided, the growth of the local precious tree species can be promoted, meanwhile, the updating and the growth of eucalyptus trees are restricted, and the updating of forest stand and the optimization of forest stand structure are promoted integrally.

4. The method reserves the residues after selective cutting of the forest land and the residues for tending, and the accumulation of organic matters can accelerate the return and decomposition of nutrients, better ensure higher nutrients in soil, promote the absorption of nutrients of plants in the forest land and be beneficial to the growth of subsequent valuable tree species in the rural soil.

Detailed Description

The present invention is further illustrated by the following examples, which are provided only for illustrating the present invention and are not intended to limit the scope of the present invention.

Example 1

A eucalyptus mixed forest transformation method taking a water source conservation function as a leading factor comprises the following steps:

(1) selecting a forest land: the soil condition of the transformed eucalyptus pure forest is more than moderate, the age is between 4 and 6 years, the individual diameter grade of the trees is obviously differentiated, and the dominant trees can be obviously distinguished, wherein the number of the dominant trees is 140 trees per hectare;

(2) forest selective cutting: the method comprises the steps of retaining eucalyptus which is good in growth vigor, luxuriant in leaves and strong in vitality, selectively cutting moribund and withered trees which are easy to suffer from diseases and insect pests, have backward growth and smaller diameter grade and low-yield inferior eucalyptus, and retaining 40 plants/mu of eucalyptus after selective cutting;

(3) land preparation and hole digging: carrying out corrosion promotion on the eucalyptus pocket after selective cutting, preparing soil by adopting a non-hardening treatment method, keeping residues after selective cutting of the forest land, simultaneously manually cleaning weeds, applying a herbicide, and then excavating planting holes, wherein the specifications of the planting holes are 30cm multiplied by 35cm multiplied by 40 cm;

(4) planting the nursery stock: after weathering, applying base fertilizer to the dug planting holes, applying 220g of compound fertilizer to each planting hole, selecting more than 2-year-old seedlings of three local precious tree species of old rice, grifola frondosa and quercus robusta, wherein the seedlings are required to have good growth vigor, developed root systems and no plant diseases and insect pests, the mixed crossing ratio of the three tree species is 1:1:1, the plant number ratio of the selectively cut eucalyptus and the local precious tree species is 1:2, and artificial planting is carried out in a period of sufficient forest land moisture from early 4 months to early 5 months, the plant spacing is 3m, and the row spacing is 3 m;

(5) nursery stock tending: tending begins to be carried out in the current 6 months of planting the seedlings of the local precious tree species, the tending is carried out for 4 years continuously, and the tending mode is as follows:

tending in the first year: tending is carried out 6 months in the current year of seedling planting, grass is shoveled within the range of 2cm in radius by taking a seedling as a center, planting holes are enlarged to 45cm, additional fertilization is carried out simultaneously, 25g of organic fertilizer is applied to each planting hole, the survival rate of the seedling is investigated, and the dead seedling is replanted in time;

tending in the second year: tending is carried out 5 months in the next year of seedling planting, grass shoveling is carried out within the radius of 8cm by taking the seedling as the center, planting holes are enlarged to 65cm, additional fertilization is carried out simultaneously, 15g of potassium sulfate compound fertilizer is applied to each planting hole, and grass shoveling is carried out once after 10 months;

tending in the third year: tending the seedlings in 7 months in the third year, shoveling the grass in the range of 30cm in radius by taking the seedlings as the center, expanding planting holes to 80cm, simultaneously performing topdressing, and applying 25g of potassium sulfate compound fertilizer to each planting hole;

tending in the fourth year: tending the seedlings in 8 months in the fourth year, shoveling grass within the radius of 45cm by taking the seedlings as the center, shoveling grass once again in 10 months, and pruning and shaping;

pruning and shaping, namely pruning branches of less than 1.7 meters from the ground to the top of the nursery stock, decomposing the pruned branches into branch sections with the length of 10cm, and uniformly and flatly paving the branch sections on the forest land; the pruning and shaping method comprises the following steps: selecting a branch to be repaired, sawing the branch close to the base of the branch, sawing the lower part of the branch firstly, and then sawing the upper part of the branch to ensure that the cut is parallel to the trunk of the seedling;

(6) managing the forest trees: when nursing precious trees in the local soil, attention is paid to protecting the trees, diseases and insect pests, damage to people and livestock and forest fire are prevented, and grazing and firewood production interference are forbidden.

The surface runoff for the same month of this example is the commingled forest < eucalyptus pure forest. The details are shown in Table 1.

TABLE 1 monthly Change in surface runoff for different vegetation types

As can be seen from Table 1, the total surface runoff of the unmodified eucalyptus pure forest is 2919.80m under the condition that the total rainfall is 1415.40mm in 1-12 months³/hm²The total ground surface runoff of the modified mixed forest is 2107.24m³/hm². Compared with the pure eucalyptus forest which is not modified, the surface runoff of the modified mixed forest is reduced by 27.83%, and the forest stand accumulation amount is effectively improved.

Example 2

A eucalyptus mixed forest transformation method taking a water source conservation function as a leading factor comprises the following steps:

(1) selecting a forest land: the soil condition of the transformed eucalyptus pure forest is more than moderate, the age is between 4 and 6 years, the individual diameter grade of the trees is obviously differentiated, and the dominant trees can be obviously distinguished, wherein the number of the dominant trees is 120 trees per hectare;

(2) forest selective cutting: the method comprises the steps of reserving the eucalyptus which is good in growth vigor, luxuriant in leaves and strong in vitality, selectively cutting the endangered and dead trees which are easy to suffer from diseases and insect pests, have backward growth and smaller diameter grade and the low-yield inferior eucalyptus, and reserving 30 eucalyptus plants/mu after selective cutting;

(3) land preparation and hole digging: carrying out corrosion promotion on the eucalyptus pocket after selective cutting, preparing soil by adopting a non-hardening treatment method, keeping residues after selective cutting of the forest land, simultaneously manually cleaning weeds, applying a herbicide, and then excavating planting holes, wherein the specifications of the planting holes are 35cm multiplied by 40cm multiplied by 45 cm;

(4) planting the nursery stock: after weathering, applying base fertilizer to the dug planting holes, applying 250g of compound fertilizer to each planting hole, selecting more than 2-year-old seedlings of two local precious tree species of old rice, quercus robusta and quercus robusta, requiring good seedling growth, developed root system and no disease and insect damage, wherein the mixed crossing ratio of the three tree species is 1:1, the plant number ratio of the selectively cut eucalyptus and the local precious tree species is 1:1, and carrying out artificial planting in a period of sufficient forest land water from 4 months to 5 months, wherein the plant spacing is 2m, and the row spacing is 4 m;

(5) nursery stock tending: tending is carried out at 6 months in the current year of planting the nursery stocks of the local precious tree species, the continuous tending is carried out for 5 years, and the tending mode is as follows:

tending in the first year: tending the seedlings in 6 months of the year, taking the seedlings as centers, shoveling grass within the radius of 1cm, enlarging planting holes to 45cm, simultaneously performing topdressing, applying 20g of organic fertilizer to each planting hole, investigating the survival rate of the seedlings, and timely replanting dead seedlings;

tending in the second year: tending is carried out 6 months in the next year of seedling planting, grass shoveling is carried out within the radius of 5cm by taking the seedling as the center, planting holes are enlarged to 70cm, additional fertilization is carried out simultaneously, 10g of potassium sulfate compound fertilizer is applied to each planting hole, and grass shoveling is carried out once again after 9 months;

tending in the third year: tending the seedlings in 7 months in the third year, shoveling the grass in the range of 25cm in radius by taking the seedlings as the center, enlarging planting holes to 90cm, simultaneously performing topdressing, and applying 20g of potassium sulfate compound fertilizer to each planting hole;

tending in the fourth year: tending the seedlings in 7 months in the fourth year, shoveling grass within the radius of 40cm by taking the seedlings as the center, shoveling grass once again in 9 months, and pruning and shaping;

tending in the fifth year: tending is carried out 10 months in the fifth year of seedling planting, grass is shoveled within the radius of 70cm by taking the seedlings as the center, pruning and shaping are carried out simultaneously, and endangered, pressed and withered trees are selectively cut;

pruning and shaping, namely pruning branches of 1.7 meters below from the ground to the top of the nursery stock, decomposing the pruned branches into branch sections with the length of 15cm, and uniformly and flatly paving the branch sections on the forest land; the pruning and shaping method comprises the following steps: selecting a branch to be repaired, sawing the branch close to the base of the branch, sawing the lower part of the branch firstly, and then sawing the upper part of the branch to ensure that the cut is parallel to the trunk of the seedling;

(6) managing the forest trees: when nursing precious trees in the local soil, attention is paid to protecting the trees, diseases and insect pests, damage to people and livestock and forest fire are prevented, and grazing and firewood production interference are forbidden.

The surface runoff for the same month of this example is the commingled forest < eucalyptus pure forest. The details are shown in Table 2.

TABLE 2 monthly Change in surface runoff for different vegetation types

Month of the year	Rainfall (mm)	Surface runoff (m) of mixed forest3/hm2)	Surface runoff (m) of eucalyptus pure forest3/hm2)
				1	120.50	62.42	180.50
2	7.20	0	0
				3	42.50	0	0
4	110.40	58.58	165.82
				5	350.20	400.65	615.36
6	200.80	382.64	532.54
				7	195.60	202.66	356.87
8	184.50	230.05	385.64
				9	130.20	224.65	376.83
10	100.20	50.40	182.24
				11	120.60	58.87	200.59
12	50.50	0	0
				Total up to	1613.20	1670.92	2996.39

As can be seen from Table 2, the total surface runoff of the unmodified eucalyptus pure forest is 2996.39m under the condition that the total rainfall is 1613.20mm in 1-12 months³/hm²The total ground surface runoff of the modified mixed forest is 1670.92m³/hm². Compared with the pure eucalyptus forest which is not modified, the surface runoff of the modified mixed forest is reduced by 44.24%, and the forest stand accumulation amount is effectively improved.

Example 3

A eucalyptus mixed forest transformation method taking a water source conservation function as a leading factor comprises the following steps:

(1) selecting a forest land: the soil condition of the transformed eucalyptus pure forest is more than moderate, the age is between 4 and 6 years, the individual diameter grade of the trees is obviously differentiated, and the dominant trees can be obviously distinguished, wherein the number of the dominant trees is 150 trees per hectare;

(2) forest selective cutting: the eucalyptus with good growth vigor, luxuriant branches and strong vitality is reserved, the endangered and dead trees with poor diameter grade and low yield which are easy to suffer from diseases and insect pests, are selected for cutting, and 45 plants/mu of eucalyptus are reserved after the cutting;

(3) land preparation and hole digging: carrying out corrosion promotion on the eucalyptus pocket after selective cutting, preparing soil by adopting a non-hardening treatment method, keeping residues after selective cutting of the forest land, simultaneously manually cleaning weeds, applying a herbicide, and then excavating planting holes, wherein the specifications of the planting holes are 40cm multiplied by 30cm multiplied by 35 cm;

(4) planting the nursery stock: after weathering, applying base fertilizer to the dug planting holes, applying 200g of compound fertilizer to each planting hole, selecting more than 2-year-old seedlings of two local precious tree species of ash woodlotus and quercus robusta, wherein the seedlings are required to have good growth vigor, developed root systems and no plant diseases and insect pests, the mixed crossing ratio of the three tree species is 1:1:1, the plant number ratio of the cut eucalyptus to the local precious tree species is 1:1, artificial planting is carried out in a period of sufficient water in the forest land from early 4 months to early 5 months, the plant spacing is 3m, and the row spacing is 4 m;

(5) nursery stock tending: tending is carried out at 6 months in the current year of planting the nursery stocks of the local precious tree species, the continuous tending is carried out for 5 years, and the tending mode is as follows:

tending in the first year: tending is carried out 6 months in the current year of seedling planting, grass is shoveled within the radius of 1cm by taking a seedling as a center, planting holes are enlarged to 50cm, additional fertilization is carried out simultaneously, 30g of organic fertilizer is applied to each planting hole, the survival rate of the seedling is investigated, and the dead seedling is replanted in time;

tending in the second year: tending is carried out 6 months in the next year of seedling planting, grass shoveling is carried out within the radius of 10cm by taking the seedling as the center, planting holes are enlarged to 60cm, additional fertilization is carried out simultaneously, 10g of potassium sulfate compound fertilizer is applied to each planting hole, and grass shoveling is carried out once again after 9 months;

tending in the third year: tending the seedlings in 7 months in the third year, shoveling the grass in the range of 25cm in radius by taking the seedlings as the center, expanding planting holes to 75cm, simultaneously performing topdressing, and applying 30g of potassium sulfate compound fertilizer to each planting hole;

tending in the fourth year: tending the seedlings in 8 months in the fourth year, shoveling grass within the radius of 50cm by taking the seedlings as the center, shoveling grass once again in 10 months, and pruning and shaping;

tending in the fifth year: tending is carried out 10 months in the fifth year of seedling planting, grass is shoveled within the radius of 60cm by taking a seedling as a center, pruning and shaping are carried out simultaneously, and endangered, pressed and withered trees are selectively cut;

pruning and shaping, namely pruning branches of 1.7 meters below from the ground to the top of the nursery stock, decomposing the pruned branches into branch sections with the length of 20cm, and uniformly and flatly paving the branch sections on the forest land; the pruning and shaping method comprises the following steps: selecting a branch to be repaired, sawing the branch close to the base of the branch, sawing the lower part of the branch firstly, and then sawing the upper part of the branch to ensure that the cut is parallel to the trunk of the seedling;

(6) managing the forest trees: when nursing precious trees in the local soil, attention is paid to protecting the trees, diseases and insect pests, damage to people and livestock and forest fire are prevented, and grazing and firewood production interference are forbidden.

The surface runoff for the same month of this example is the commingled forest < eucalyptus pure forest. The details are shown in Table 3.

TABLE 3 monthly Change in surface runoff for different vegetation types

Month of the year	Rainfall (mm)	Surface runoff (m) of mixed forest3/hm2)	Surface runoff (m) of eucalyptus pure forest3/hm2)
				1	100.80	58.82	135.48
2	30.90	0	0
				3	40.80	0	0
4	105.40	72.54	154.26
				5	290.60	387.46	574.63
6	395.80	505.34	820.46
				7	120.50	75.58	210.25
8	118.50	75.25	210.08
				9	198.40	280.08	350.62
10	102.90	62.24	138.85
				11	180.20	254.68	368.21
12	100.40	60.06	130.65
				Total up to	1785.20	1832.05	3093.49

As can be seen from Table 3, the total surface runoff of the unmodified eucalyptus pure forest is 3093.49m under the condition that the total rainfall is 1785.20mm in 1-12 months³/hm²The total ground surface runoff of the modified mixed forest is 1832.05m³/hm². Compared with the pure eucalyptus forest which is not modified, the surface runoff of the modified mixed forest is reduced by 40.78%, and the forest stand accumulation amount is effectively improved.

Example 4

A eucalyptus mixed forest transformation method taking a water source conservation function as a leading factor comprises the following steps:

(1) selecting a forest land: the soil condition of the transformed eucalyptus pure forest is more than moderate, the age is between 4 and 6 years, the individual diameter grade of the trees is obviously differentiated, and the dominant trees can be obviously distinguished, wherein the number of the dominant trees is 125 trees per hectare;

(2) forest selective cutting: the method comprises the steps of retaining eucalyptus which is good in growth vigor, luxuriant in leaves and strong in vitality, selectively cutting moribund and withered trees which are easy to suffer from diseases and insect pests, have backward growth and smaller diameter grade and low-yield and poor-quality eucalyptus, and retaining 32 plants/mu of eucalyptus after selective cutting;

(3) land preparation and hole digging: carrying out corrosion promotion on the eucalyptus pocket after selective cutting, preparing soil by adopting a non-hardening treatment method, keeping residues after selective cutting of the forest land, simultaneously manually cleaning weeds, applying a herbicide, and then excavating planting holes, wherein the specifications of the planting holes are 30cm multiplied by 35cm multiplied by 30 cm;

(4) planting the nursery stock: after weathering, applying base fertilizer to the dug planting holes, applying 300g of compound fertilizer to each planting hole, selecting more than 2-year-old seedlings of two local precious tree species of old rice, old lotus and grifola frondosa, wherein the seedlings are required to have good growth vigor, developed root systems and no diseases and insect pests, the mixed crossing ratio of the three tree species is 1:1, the plant number ratio of the selectively cut eucalyptus and the local precious tree species is 1:2, and manual planting is carried out in a period of sufficient forest land water from early 4 months to early 5 months, wherein the plant spacing is 3m, and the row spacing is 4 m;

(5) nursery stock tending: tending begins to be carried out in the current 6 months of planting the seedlings of the local precious tree species, the tending is carried out for 4 years continuously, and the tending mode is as follows:

tending in the first year: tending the seedlings in 6 months of the year, taking the seedlings as centers, shoveling grass within the radius of 2cm, enlarging planting holes to 48cm, simultaneously performing topdressing, applying 23g of organic fertilizer to each planting hole, investigating the survival rate of the seedlings, and timely replanting dead seedlings;

tending in the second year: tending the seedlings in 5 months in the next year, shoveling the grass within the radius of 5cm by taking the seedlings as the center, expanding planting holes to 70cm, simultaneously performing topdressing, applying 20g of potassium sulfate compound fertilizer to each planting hole, and shoveling the grass once after 10 months;

tending in the third year: tending is carried out 6 months in the third year of seedling planting, grass spading is carried out within the radius of 20cm by taking the seedlings as the center, planting holes are enlarged to 75cm, topdressing is carried out simultaneously, and 20g of potassium sulfate type compound fertilizer is applied to each planting hole;

tending in the fourth year: tending the seedlings in 8 months in the fourth year, shoveling grass within the radius of 40cm by taking the seedlings as the center, shoveling grass once again in 10 months, and pruning and shaping;

pruning and shaping, namely pruning branches of less than 1.7 meters from the ground to the top of the nursery stock, decomposing the pruned branches into branch sections with the length of 10cm, and uniformly and flatly paving the branch sections on the forest land; the pruning and shaping method comprises the following steps: selecting a branch to be repaired, sawing the branch close to the base of the branch, sawing the lower part of the branch firstly, and then sawing the upper part of the branch to ensure that the cut is parallel to the trunk of the seedling;

(6) managing the forest trees: when nursing precious trees in the local soil, attention is paid to protecting the trees, diseases and insect pests, damage to people and livestock and forest fire are prevented, and grazing and firewood production interference are forbidden.

The surface runoff for the same month of this example is the commingled forest < eucalyptus pure forest. The details are shown in Table 4.

TABLE 4 monthly Change in surface runoff for different vegetation types

Month of the year	Rainfall (mm)	Surface runoff (m) of mixed forest3/hm2)	Surface runoff (m) of eucalyptus pure forest3/hm2)
				1	98.60	55.20	132.48
2	20.50	0	0
				3	30.30	0	0
4	55.80	0	0
				5	112.60	68.25	180.63
6	180.50	258.64	387.52
				7	84.30	55.38	120.67
8	275.40	375.39	550.08
				9	92.20	49.24	129.36
10	38.40	0	0
				11	43.20	0	0
12	39.50	0	0
				Total up to	1071.30	862.10	1500.74

As can be seen from Table 4, the total surface runoff of the unmodified eucalyptus pure forest is 1500.74m under the condition that the total rainfall is 1071.30mm in 1-12 months³/hm²The total ground surface runoff of the modified mixed forest is 862.10m³/hm². Compared with the pure eucalyptus forest which is not modified, the surface runoff of the modified mixed forest is reduced by 42.56%, and the forest stand accumulation amount is effectively improved.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and the like that are within the spirit and principle of the present invention are included in the present invention.