Structure regulation and control method for inefficient Yunnan pine forest

Abstract

The invention relates to the technical field of forest tending, in particular to a structure regulation and control method for a pinus yunnanensis low-efficiency forest. The pinus yunnanensis low-efficiency forest structure regulation and control method comprises the following steps that ecological thinning is conducted on a pinus yunnanensis low-efficiency forest region, broad-leaved trees are planted in an intermediate cutting zone in a complementary mode according to the mixing proportion of 30% or below, and pinus yunnanensis lateral branches are pruned. According to the structure regulation and control method, good growth of the Yunnan pine forest is promoted, the diameter order range of the forest stand is expanded, the forest stand is converted into a needle-broad mixed different-age forest stand, the forest stand is gradually transited to random distribution or cluster distribution, the complexity and diversity of a natural ecological system can be better reflected, optimization of a forest stand space structure is promoted, and the economic benefit is increased. And a condition and a basis are provided for realizing a multifunctional effect of the forest.

Description

Technical Field

[0001] The invention belongs to the technical field of forest tending, and specifically relates to a structural control method for a low-efficiency Yunnan pine forest. Background Art

[0002] Yunnan pine (Pinus yunnanensis) is an important tree species widely distributed in southwest China, with important ecological, economic and social values. However, due to the limitations of natural growth conditions and unreasonable management, the tree species structure of Yunnan pine stands is relatively simple, the stand density is too large, the tree trunk shape is poor, the branches are low, and the individual quality is poor, resulting in stands with few tree diameters, poor growth potential and small annual average growth, forming a large area of ​​inefficient forests with poor stand stability, frequent pests and diseases, and declining ecosystem service functions.

[0003] This not only affects the sustainable use of forestry resources, but also weakens its ecological functions in protection and carbon fixation. Therefore, an effective technical means is urgently needed to improve the stand structure of low-efficiency Yunnan pine forests and enhance their ecological and economic benefits. Summary of the invention

[0004] In view of the above technical problems, the present invention provides a method for structural regulation of low-efficiency Yunnan pine forests.

[0005] The technical solution of the present invention is as follows:

[0006] The invention provides a structural control method for a low-efficiency Yunnan pine forest, comprising the following steps: ecological thinning the low-efficiency Yunnan pine forest, replanting broad-leaved trees in the thinning zone at a mixed ratio of less than 30%, and pruning the side branches of the Yunnan pine.

[0007] In the present invention, the ecological thinning includes retaining marginal trees, critical trees, isolated trees, and cutting down dead trees, dying trees, pressed trees, old trees, overlord trees, and medium-sized trees. In one embodiment, the ecological thinning has a felling intensity of no more than 15%-20% of the total number of trees. In one embodiment, the density of Yunnan pine after ecological thinning is 500-800 trees / hm 2 , the canopy density is 0.6-0.8 ， This thinning method expanded the diameter range of Yunnan pine and promoted the cultivation of large-diameter timber. After thinning, the average volume per tree increased by 41.7%.

[0008] In the present invention, the broad-leaved tree replanting density is 200-350 plants / hm2. 2. In one embodiment, the replanting time is from June to August. In one embodiment, the replanting is a mixed block of Yunnan pine and broad-leaved trees, and the mixed ratio of Yunnan pine to broad-leaved trees is 4-6:1. In one embodiment, the broad-leaved trees include one or more of Alnus nepalensis, Castanopsis delavayi, and Quercus glaucoides. In one embodiment, the broad-leaved trees are bagged seedlings less than 2 years old. In one embodiment, the replanting adopts fixed-planting pit planting, the pit depth is 30-40 cm, and the pit diameter is 20-30 cm. This replanting method improves the biodiversity of the forest stand, and improves the soil nutrients and stability of the forest stand.

[0009] In the present invention, the pruning amount of side branches does not exceed 20% of the branches, and the side branches are pruned between 50-100 cm from the ground, and the overcrowded, crossed, and dead branches are removed to ensure the upright growth of the tree trunk. In one embodiment, the pruning time is spring every year to avoid the peak growth season; in one embodiment, the pruning height of the side branches does not exceed 1 / 3 of the main trunk to avoid the weakening of the growth potential of the tree due to excessive pruning.

[0010] Compared with the prior art, the present invention has the following beneficial effects:

[0011] 1. The structural regulation method of the present invention promotes the good growth of Yunnan pine forests, expands the diameter range of forest stands, increases the average volume of individual trees by 41.7%, and gradually transitions forest stands to random distribution or clustered distribution, which better reflects the complexity and diversity of natural ecosystems, promotes the optimization of forest stand spatial structure, and provides conditions and basis for the realization of multifunctional effects of forests.

[0012] 2. The structural regulation method of the present invention has a significant promoting effect on the natural regeneration of other trees, shrubs and grass species under the forest, and can enable a large number of broad-leaved tree species and other naturally regenerated tree species to enter the main forest layer, transforming them into mixed coniferous and broad-leaved stands of different ages, thereby improving the biodiversity and stability of the forest stand.

[0013] 3. The structural regulation method of the present invention can increase the organic matter content in the surface layer of forest soil. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 To control the distribution of DBH and plant number in sample and control plots;

[0015] Figure 2 This is the distribution curve of tree height and breast diameter. DETAILED DESCRIPTION

[0016] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is described in detail below in conjunction with embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0017] In the following examples, unless otherwise specified, the analysis methods recommended by Nanjing Institute of Soil Science, Chinese Academy of Sciences were used for detection, which are all conventional methods. All data were tested by normal distribution test and variance consistency test, and the significance of parameter differences before and after stand structure adjustment and between treatments was tested by independent sample t test. The above statistical analysis was processed by SPSS11.0 software.

[0018] Unless otherwise specified, the materials and reagents used in the following examples can be obtained from commercial sources.

[0019] The study area of ​​the present invention is located in Taihejiang Forest Farm, Shuangbai County, Chuxiong Yi Autonomous Prefecture, Yunnan Province. The growth of Yunnan pine trees here is declining, with poor trunk shape, low branches, and low economic timber utilization rate; the forest stands are overgrown with shrubs and weeds, the forest density is too large, the understory regeneration is poor, the forest ecosystem function is poor, and the forest stand is seriously declining. It belongs to the low-efficiency Yunnan pine forest in the central Yunnan plateau.

[0020] The stand control plots and control plots were set up in the study area. The control plots were not treated. The main measures for the control plots were as follows: 1. Ecological thinning: felling dead trees, dying trees and depressed trees were removed. The intensity of ecological thinning did not exceed 15%-20% of the total number of trees. The density of Yunnan pine after felling was 500-800 trees / hm2. 2 , the density is 0.6-0.8. 2. Replanting and renewal: In June-August, replant the one-year-old bag seedlings of winter melon, Castanopsis alpiniae, and Photinia fraseri in blocks and mix them in the thinning area. Plant them in holes with a depth of 30-40cm and a diameter of 20-30cm. The replanting density of broad-leaved tree seedlings is 200-350 plants / hm2. 2 , the mixed ratio is 4:1. 3. Pruning: Prune the side branches every spring, the pruning amount should not exceed 20% of the branches, prune the side branches between 50-100cm from the ground, and the pruning height of the side branches should not exceed 1 / 3 of the main trunk.

[0021] Using the typical sampling method, sample plot surveys were conducted in representative sections of the structure control plots and control plots before and after the stand structure adjustment in February and March 2012 and in March 2017. Four 20m×20m sample plots were set up in each plot, and each tree in the sample plot was surveyed, and the height, breast diameter, and crown width of each tree were recorded. A 1m×1m small sample plot was set up at the four corners and the center point of each sample plot to investigate the forest understory regeneration. Soil surface samples (excluding litter and humus layer) were collected at multiple points in the sample plot to form mixed samples. A total of 10 soil mixed samples were collected each time, and ring knife samples were collected at the same time to measure the thickness of the humus layer.

[0022] 1. Impact of structural regulation on forest characteristics

[0023] 1.1 Changes in plant number and diameter class distribution after structural regulation

[0024] The distribution changes of DBH and plant number in the control plots and control plots in 2017 are as follows Figure 1 As shown by Figure 1 It can be seen that, compared with the control plot, the DBH distribution curve of the regulated plot shifts to the right, and the range of diameter classes also increases. This indicates that after structural regulation of the present invention, large-diameter trees are gradually formed, the number of small-diameter trees is increased, and the proportion of plants of different ages is increased.

[0025] 1.2 Changes in various indicators after structural adjustment

[0026] The changes in stand density, stock, basal area at breast height, average stock, average basal area at breast height, average tree height, and average diameter were measured in the structure control plots and the control plots. The tree height was calculated based on the tree height curve (see Figure 2 ) calculation, and the measurement results of various indicators are shown in Table 1.

[0027] Table 1 Measured values ​​of forest classification in control and control plots from 2012 to 2017

[0028]

[0029] As shown in Table 1, the growth of breast height sectional area, average single plant accumulation, average breast height sectional area, average tree height, and average breast diameter of the structure-controlled plots in 2017 was significantly higher than that of the control plots, increasing by 28.04%, 41.7%, 80.9%, 11.8%, and 12.2%, respectively. This shows that although the stand density of the stand structure-controlled plots has decreased significantly compared with that before the regulation, the growth rate of growth indicators such as accumulation, plant height, and breast diameter has increased significantly compared with the control plots.

[0030] 1.3 Changes in plant distribution after structural regulation

[0031] The angular scales of the control plots and control plots in 2012 and 2017 are shown in Table 2. Among them, the stands with angular scales between 0.475 and 0.517 were randomly distributed, the stands with angular scales greater than 0.517 were clumped, and the stands with angular scales less than 0.475 were evenly distributed.

[0032] Table 2 Angular scales of structural control plots and control plots from 2012 to 2017

[0033]

[0034] As shown in Table 2, the regulated sample plots of the present invention show random distribution and clustered distribution, while the control sample plots show uniform distribution, which indicates that the forest stands regulated by the structure of the present invention are transformed into natural forest stands without human intervention, which can reflect the complexity and diversity of natural ecosystems and improve the stability of forest stands.

[0035] 2. Effects of structural regulation on the growth of understory species

[0036] 2.1 Effects of regulation on the height and coverage of understory broadleaved trees

[0037] In 2017, the average height of understory broad-leaved trees in the regulated plots was 79 cm, while the average height in the control plots was 64 cm, an increase of 23% in the average height of broad-leaved trees in the regulated plots compared with the control plots; in 2017, the coverage of understory broad-leaved trees in the regulated plots was 47%, while the coverage in the control plots was 28%, an increase of 19% in the coverage of broad-leaved trees in the regulated plots compared with the control plots.

[0038] 2.2 Effects of regulation on species composition and quantity of natural regeneration understory

[0039] In 2017, there were 13 broad-leaved trees under the control plot, including Quercus alba, Quercus acutissima, and Psoralea corylifolia, with a natural regeneration rate of 1.2 plants / m 2 In 2017, there were 21 broad-leaved trees under the forest in the controlled plot. In addition to the above three broad-leaved tree species, the natural regeneration also included water hyacinth, emblica, purple holly, Schima superba and pyrocalyx, and the number of plants naturally regenerated was 4.0 plants / m 2 , which is 3.3 times that of the control plot. This shows that the structural regulation of the present invention is beneficial to the growth of understory plants, promotes the natural regeneration of other understory trees, shrubs and grasses, and improves the broad-leaved tree species.

[0040] 3. Effects of structural regulation on soil physical and chemical characteristics

[0041] Typical and representative sections of the structural regulation sample plot of the present invention were selected, and 12 sample points were collected respectively. Soil samples were collected at the surface or 0 layer (0-20 cm), middle layer (20 cm-40 cm) and lower layer (40 cm-60 cm), and sent to the Analysis and Testing Center of Yunnan Academy of Agricultural Sciences for chemical analysis, and the effects of forest stand structure regulation on the physical and chemical properties of forest soil were analyzed and compared.

[0042] 3.1 Changes in organic matter content and pH value in soil layers of different forest stands

[0043] The analysis and test results of organic matter content and pH value in each layer of soil in different forest stands in 2013 and 2017 are shown in Tables 3, 4 and 5.

[0044] Table 3 Organic matter content and pH value of surface soil

[0045]

[0046] Table 4 Organic matter content and pH of the middle layer soil

[0047]

[0048] Table 5 Organic matter content and pH of lower soil

[0049]

[0050] Compared with the organic matter content in 2013, the organic matter content of the surface soil of the regulated plots increased by 31.85% in 2017, and the control plots increased by 18.05%, the former being 13.80% higher than the latter; the organic matter content of the middle soil of the regulated plots increased by 8.67%, and the control plots increased by 4.44%, the former being 4.23% higher than the latter; while the organic matter content of the underground soil of the regulated plots and the control plots showed a downward trend, decreasing by 17.75% and 17.77% respectively, indicating that the structural regulation of the present invention significantly increased the organic matter content of the 0-40cm soil of the regulated plots, and was significantly higher than that of the control plots (p<0.05), and the increase in the organic matter content of the 0-20cm soil was greater. It shows that the structural regulation of the present invention improves the physical and chemical properties of the forest soil and greatly improves the overall benefits of the forest stand quality.

[0051] In 2013, the pH value of the surface soil in the regulated plot was higher than that in the control plot, but the result in 2017 was just the opposite, and both were lower than the values ​​measured in 2013. The pH value decrease rate of the surface soil in the regulated plot (14.64%) was higher than that in the control plot (9.32%). The pH value changes in the middle and lower layers of the soil were similar to those in the surface soil, but the pH value decrease rate of the middle layer of the regulated plot (9.16%) was lower than that in the control plot (11.35%), and the pH value decrease rate of the lower layer of the regulated plot (9.28%) was slightly higher than that in the control forest (8.92%). The above results show that the soil in the Yunnan pine forest is generally acidic, and the pH value does not change much with the increase of soil depth. The soil acidification phenomenon in the Yunnan pine forest in this area is obvious.

[0052] 3.2 Changes in physical and chemical properties of surface soil in different forest stands

[0053] The analysis and test results of soil nutrients in the surface soil of different forest stands in 2013 and 2017 are shown in Tables 6, 7 and 8.

[0054] Table 6 Effects of stand structure regulation on surface litter and soil physical properties

[0055]

[0056] In terms of the existing amount of litter (Table 6), after the stand structure was controlled, the existing amount of litter in the Yunnan pine forest decreased significantly, and the controlled sample was 80% of that in the control sample. The ratio of coniferous to broad-leaved litter in the existing litter (coniferous litter / broad-leaved litter) also decreased from 19.65 to 8.11; the water content of litter in the controlled sample was slightly lower than that in the control sample, but the difference between the two was not significant; there was no significant difference in the water content of coniferous litter between the controlled sample and the control sample, but the water content of broad-leaved litter in the controlled sample was significantly lower than that in the control sample, only 86.39% of that in the control sample, which may be related to the changes in broad-leaved tree species.

[0057] In terms of soil physical properties (Table 6), after the stand structure was controlled, the thickness of the soil humus layer and the surface temperature of the Yunnan pine forest changed significantly. The thickness of the humus layer in the controlled sample plot was significantly reduced, which was 62% of the control sample plot, which may be related to the clearing of the forest land during the stand structure control. The surface temperature (13.36℃) was significantly higher than that of the control sample plot (12.74℃); the soil moisture content and soil density of the controlled sample plot were slightly higher than those of the control sample plot, but the differences were not significant.

[0058] Table 7 Effects of stand structure adjustment on the chemical properties of surface soil

[0059]

[0060] In terms of soil chemical properties, after the stand structure was regulated, the soil pH, total nutrient content and effective nutrient content did not change significantly (Table 7). Among them, the soil organic matter content of the regulated plots increased significantly, increasing by 10.42% compared with the control plots, while the content of effective nutrients (P and K) in the soil was lower than that of the control plots, but the difference between the two was not significant.

[0061] Table 8 Effects of stand structure adjustment on surface soil microbial properties

[0062]

[0063] In terms of soil microbial activity (Table 8), after the stand structure was regulated, the soil microbial biomass and soil basal respiration increased significantly. Among them, the microbial biomass C, N, and P of the regulated plots increased by 12.18%, 13.17%, and 20.78% respectively compared with the control plots, and the basal respiration increased by 31.25%; however, the microbial biomass ratio (C:N, C:P) and soil respiration entropy in different treatment plots were not significantly different. The above test results show that the structural regulation method of the present invention can increase the organic matter content of the surface layer of forest soil, and has little effect on the organic matter content of deep soil.

[0064] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for structural regulation of low-efficiency Yunnan pine forests, characterized in that: The following steps are involved: Carry out ecological thinning of low-efficiency Yunnan pine forests, replant broad-leaved trees in the thinning belts at a mixed ratio of less than 30%, and prune the side branches of Yunnan pine.

2. The control method according to claim 1, characterized in that: The ecological thinning includes retaining edge trees, critical trees, isolated trees, and cutting down dead and fallen trees, dying trees, depressed trees, old trees, overlord trees, and medium-sized trees.

3. The control method according to claim 1 or 2, characterized in that: The ecological thinning has a felling intensity of no more than 15%-20% of the total number of trees.

4. The control method according to claim 1 or 2, characterized in that: The density of Yunnan pine after ecological thinning is 500-800 plants / hm2 2 , the canopy density is 0.6-0.

8.

5. The control method according to claim 1, characterized in that: The broad-leaved trees include one or more of Alnus nepalensis, Castanopsis delavayi and Quercus glaucoides.

6. The control method according to claim 1, characterized in that: The broad-leaved tree replanting density is 200-350 plants / hm2 2 .

7. The control method according to claim 1, characterized in that: The mixed ratio of Yunnan pine and broad-leaved trees is 4-6:

1.

8. The control method according to claim 1 or 6, characterized in that: The replanting is carried out by planting in holes, the hole depth is 30-40cm, and the hole diameter is 20-30cm.

9. The control method according to claim 1, characterized in that: The pruning amount of side branches should not exceed 20% of the branches, and the side branches should be pruned between 50-100cm from the ground.

10. The control method according to claim 1, characterized in that: The pruning height of side branches should not exceed 1 / 3 of the main trunk.

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