Method for screening broad-leaved tree species suitable for being mixed with cunninghamia lanceolata and application of broad-leaved tree species

Abstract

The invention provides a method for screening broad-leaved tree species suitable for being mixed with cunninghamia lanceolata, and belongs to the technical field of forest tree management. The cunninghamia lanceolata and broad-leaved trees are subjected to mixed afforestation, and meanwhile, a cunninghamia lanceolata pure forest is built as a yield measurement control; the method comprises the following steps: comparing the accumulation of a cedarwood / broad-leaved tree mixed forest and a cedarwood pure forest, the single-plant wood volume of cedarwood in the cedarwood / broad-leaved tree mixed forest and the single-plant wood volume growth amount of the cedarwood pure forest, and comparing the outturn percentage of the cedarwood standard wood species in the cedarwood / broad-leaved tree mixed forest and the outturn percentage of the standard wood species of the cedarwood pure forest; finally, broad-leaved tree species suitable for being mixed with the cunninghamia lanceolata are screened out. Cunninghamia lanceolata and broad-leaved tree species screened by the method are mixed, so that the wood yield of the artificial cunninghamia lanceolata forest and the outturn percentage of large and medium-sized timber species can be increased, the stand growth performance is excellent, the production requirements on the cunninghamia lanceolata under the existing conditions can be effectively met, and meanwhile, the method has relatively high economic benefits and ecological benefits and has a wide application prospect.

Description

Technical Field

[0001] The invention relates to the technical field of forest management, and in particular to a method for screening broad-leaved tree species suitable for interbreeding with Chinese fir and application thereof. Background Art

[0002] Chinese fir is a coniferous timber species with the largest timber production and the highest yield of large-diameter timber in southern my country. At present, Chinese fir generally adopts an intensive management model of multiple afforestation on the same afforestation land. Long-term forestry production practice has shown that due to the biological characteristics of Chinese fir and the influence of traditional cultivation methods, continuous planting of pure Chinese fir forests has caused many problems such as soil fertility decline and forest habitat deterioration. The timber production and yield of large and medium-sized timber species of Chinese fir plantations have declined to varying degrees, which not only reduces the operating income of timber production units, but also aggravates the contradiction between timber supply and demand. Therefore, how to change the traditional management mode of Chinese fir, improve the timber production and quality of Chinese fir plantations, and realize the sustainable management of Chinese fir plantations has become a technical problem that forestry workers today urgently need to solve.

[0003] A large number of studies have shown that building mixed fir and broad-leaved forests is the best way to solve the problems of reduced wood production and low quality caused by continuous planting of fir. To this end, since the 1980s, many forestry workers have built a large number of different types of mixed fir and broad-leaved forests in terms of mixed tree species composition, mixed plant ratio and mixed method. However, because the traditional mixed model ignores the differences in ecological characteristics between tree species and many problems in afforestation density and forest management, the mixed effect of mixed fir and broad-leaved forests is not good and cannot achieve the expected purpose.

[0004] Selecting broad-leaved tree species that have a mutually beneficial or complementary effect with Chinese fir and planting them together with Chinese fir, building mixed Chinese fir / broad-leaved tree forests, improving the habitat conditions of Chinese fir through broad-leaved trees or reducing the competition intensity of adjacent trees in pure Chinese fir forests, and thus increasing the yield of Chinese fir wood and the proportion of large and medium-sized wood species, has become one of the important management measures to solve the current decline in the yield and quality of Chinese fir wood. The selection of broad-leaved tree species suitable for planting with Chinese fir is the basic premise of this measure. However, there is currently no method for selecting broad-leaved tree species suitable for planting with Chinese fir. Summary of the invention

[0005] The purpose of the present invention is to provide a method for screening broad-leaved tree species suitable for mixed planting with Chinese fir and its application, so as to solve the problem of reduced yield and timber recovery rate of pure Chinese fir forest in the prior art.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a method for screening broad-leaved tree species suitable for interplanting with Chinese fir, comprising the following steps:

[0008] S1. Select afforestation land with a fir status index of 14 or above;

[0009] S2. Mix Chinese fir and broad-leaved trees for afforestation, and simultaneously establish a pure Chinese fir forest as a control for yield measurement;

[0010] S3. During the growth of mixed fir / broadleaved forests, if the canopy of broadleaved trees shades the canopy of adjacent fir trees by more than 1 / 3, thinning should be performed on both the fir and broadleaved trees;

[0011] S4. Determine the rotation period based on the status index of Chinese fir trees in the afforestation land;

[0012] S5. Compare the stock accumulation of mixed fir / broadleaved forests and pure fir forests after felling during the rotation period;

[0013] If the stock of the mixed fir / broad-leaved forest is less than that of the pure fir forest, exclude the mixed afforestation of the broad-leaved tree species with fir; if the stock of the mixed fir / broad-leaved forest is greater than that of the pure fir forest, continue to make the following comparison:

[0014] (1) Compare the timber volume growth of individual Chinese fir trees in mixed Chinese fir / broadleaved forests and that of pure Chinese fir forests;

[0015] (2) To compare the yield of standard species of Chinese fir in mixed Chinese fir / broadleaved forests with that in pure Chinese fir forests;

[0016] If the timber volume growth of individual Chinese fir trees in a mixed forest is greater than that of a pure Chinese fir forest, and the yield of large-diameter and medium-diameter Chinese fir species in a mixed Chinese fir / broad-leaved tree forest is increased by 18% and 30% respectively compared with that in a pure Chinese fir forest, then the broad-leaved tree species is determined to be suitable for mixing with Chinese fir.

[0017] Preferably, the afforestation land in S1 is a habitat that can meet the needs of local native broad-leaved tree species to complete their life cycle.

[0018] Preferably, the mixed planting method of fir and broad-leaved trees is row-shaped mixed planting, the spacing between rows of fir and broad-leaved trees is 2.0-2.5m, and the spacing between plants within a row is 1.5-2.0m.

[0019] Preferably, during thinning, two adjacent rows of fir and broad-leaved trees are taken as a thinning unit, and by comparing between rows and plants, the small ones are cut down and the large ones are retained, the inferior ones are cut down and the superior ones are retained, and the care is evenly distributed. The plant retention density after thinning is 45% to 50% of the initial afforestation density.

[0020] Preferably, if the fir status index of the afforestation land is 18 or above, the rotation period is 15 to 20 years; if the fir status index of the afforestation land is 16, the rotation period is 20 to 25 years; if the fir status index of the afforestation land is 14, the rotation period is 25 to 30 years.

[0021] Preferably, the large-diameter timber is Chinese fir with a breast diameter ≥ 22 cm, the medium-diameter timber is Chinese fir with a breast diameter of 16 cm ≤ breast diameter < 20 cm, and the small-diameter timber is Chinese fir with a breast diameter of 8 cm ≤ breast diameter < 14 cm.

[0022] The invention also provides application of the method in Chinese fir planting.

[0023] The invention also provides application of the method in improving the wood yield of Chinese fir plantations.

[0024] The invention also provides application of the method in improving the yield rate of standard timber species in Chinese fir plantations.

[0025] By adopting the above technical scheme, the present invention has the following beneficial effects: the present invention carries out mixed afforestation of Chinese fir and broad-leaved trees, and at the same time builds a pure Chinese fir forest as a yield measurement control, and finally screens out broad-leaved tree species suitable for mixed planting with Chinese fir by comparing the accumulation of Chinese fir / broad-leaved tree mixed forest and Chinese fir pure forest, the volume of Chinese fir single tree in Chinese fir / broad-leaved tree mixed forest and the volume growth of Chinese fir single tree in Chinese fir pure forest, and comparing the yield rate of Chinese fir standard species in Chinese fir / broad-leaved tree mixed forest and the yield rate of standard species in Chinese fir pure forest. Mixing Chinese fir with the broad-leaved tree species selected by the method can increase the wood yield and the yield rate of large and medium standard species of Chinese fir plantations, and the forest stand growth performance is excellent, which can effectively meet the production demand for Chinese fir under the current situation, and at the same time has high economic and ecological benefits, and has broad application prospects. DETAILED DESCRIPTION

[0026] The present invention provides a method for screening broad-leaved tree species suitable for interplanting with Chinese fir, comprising the following steps:

[0027] S1. Select afforestation land with a site index of 14 or above, which is suitable for the growth of Chinese fir;

[0028] S2. Mix Chinese fir and broad-leaved trees for afforestation, and simultaneously establish a pure Chinese fir forest as a control for yield measurement;

[0029] S3. During the growth of mixed fir / broadleaved forests, if the canopy of broadleaved trees shades the canopy of adjacent fir trees by more than 1 / 3, thinning should be performed on both the fir and broadleaved trees;

[0030] S4. Determine the rotation period based on the status index of Chinese fir trees in the afforestation land;

[0031] S5. Compare the stock accumulation of mixed fir / broadleaved forests and pure fir forests after felling during the rotation period;

[0032] If the stock of the mixed fir / broad-leaved forest is less than that of the pure fir forest, exclude the mixed afforestation of the broad-leaved tree species with fir; if the stock of the mixed fir / broad-leaved forest is greater than that of the pure fir forest, continue to make the following comparison:

[0033] (1) Compare the timber volume growth of individual Chinese fir trees in mixed Chinese fir / broadleaved forests and that of pure Chinese fir forests;

[0034] (2) To compare the yield of standard species of Chinese fir in mixed Chinese fir / broadleaved forests with that in pure Chinese fir forests;

[0035] If the timber volume growth of individual Chinese fir trees in a mixed forest is greater than that of a pure Chinese fir forest, and the yield of large-diameter and medium-diameter Chinese fir species in a mixed Chinese fir / broad-leaved tree forest is increased by 18% and 30% respectively compared with that in a pure Chinese fir forest, then the broad-leaved tree species is determined to be suitable for mixing with Chinese fir.

[0036] The present invention first selects afforestation land for mixed fir / broad-leaved tree forestation, which needs to meet the following conditions at the same time: (1) afforestation land with a fir status index of 14 or above; (2) a habitat that can meet the life history of local native broad-leaved tree species; (3) the afforestation land is unforested afforestation land. Fir and broad-leaved trees are planted in rows, with the row spacing between fir and broad-leaved trees being 2.0 to 2.5 m, more preferably 2.1 to 2.4 m, and more preferably 2.2 m; the spacing between plants within a row is 1.5 to 2.0 m, more preferably 1.7 to 1.9 m, and more preferably 1.8 m. During the growth of the mixed fir / broad-leaved tree forest, if the broad-leaved tree crown covers the height of the adjacent fir crown by more than 1 / 3, the fir and broad-leaved trees are thinned at the same time. During thinning, two adjacent rows of Chinese fir and broad-leaved trees are taken as a thinning unit. By comparing between rows and plants, the smaller ones are cut down and the larger ones are retained, the inferior ones are cut down and the superior ones are retained, and the trees are taken care of evenly. The plant retention density after thinning is 45% to 50% of the initial afforestation density, more preferably 46% to 49%, and more preferably 47%. The Chinese fir status index of the afforestation land is used as the rotation period determination standard. For forest stands with a Chinese fir status index of 18 or above, the rotation period is 15 to 20 years, more preferably 16 to 19 years, and more preferably 18 years; for forest stands with a Chinese fir status index of 16, the rotation period is 20 to 25 years, more preferably 21 to 24 years, and more preferably 22 years; for forest stands with a Chinese fir status index of 14, the rotation period is 25 to 30 years, more preferably 26 to 29 years, and more preferably 28 years. After rotation, the following indicators are compared:

[0037] 1. Comparison of the volume growth of individual Chinese fir trees in mixed Chinese fir / broadleaved forests and in pure Chinese fir forests

[0038] The volume of mixed fir / broad-leaved forests is the sum of the volume of individual fir trees and individual broad-leaved trees in mixed fir / broad-leaved forests; the volume of pure fir forests is the sum of the volume of all single fir trees in pure fir forests. The volume of individual fir and broad-leaved trees is calculated in accordance with the Technical Regulations for the Continuous Inventory of National Forest Resources (2014).

[0039] If the stock of a mixed fir / broad-leaved forest is greater than that of a pure fir forest, then there is a possibility that the mixture of fir and the broad-leaved tree will increase the growth of fir in the mixed forest. However, it is impossible to determine whether the increase in the stock of a mixed fir / broad-leaved forest is caused by ① an increase in the volume of both fir and broad-leaved trees; ② an increase in the volume of fir and a decrease in the volume of broad-leaved trees; or ③ a decrease in the volume of fir and an increase in the volume of broad-leaved trees. Therefore, it is necessary to further confirm how the interaction between fir and broad-leaved trees will affect the growth of fir in mixed forests. Therefore, it is necessary to continue to make the following comparisons:

[0040] (1) Compare the timber volume growth of individual Chinese fir trees in mixed Chinese fir / broadleaved forests and that of pure Chinese fir forests;

[0041] (2) To compare the yield of standard species of Chinese fir in mixed Chinese fir / broadleaved forests with that in pure Chinese fir forests;

[0042] 2. Comparison of the volume growth of individual Chinese fir trees in mixed Chinese fir / broadleaved forests and in pure Chinese fir forests

[0043] The volume of individual Chinese fir trees in the mixed Chinese fir / broad-leaved tree forest is the average volume of individual Chinese fir standing trees in the mixed Chinese fir / broad-leaved tree forest, and its volume growth is the average volume of individual trees divided by the forest age; the volume of individual Chinese fir trees in pure Chinese fir forest is the average volume of individual Chinese fir standing trees in pure Chinese fir forest, and its volume growth is the average volume of individual trees divided by the forest age.

[0044] (1) If the stock of a mixed fir / broad-leaved forest is greater than that of a pure fir forest, and the volume growth of a single fir tree in the mixed forest is greater than that of a pure fir forest, it means that the broad-leaved trees in the mixed fir / broad-leaved forest promote the growth of the fir, or that the two promote each other's growth, resulting in an increase in the volume of a single fir tree after the fir / broad-leaved tree is mixed;

[0045] (2) If the stock of a mixed fir / broad-leaved forest is greater than that of a pure fir forest, but the volume growth of a single fir tree in the mixed forest is less than that of a single fir tree in a pure fir forest, this indicates that broad-leaved trees in the mixed fir / broad-leaved forest inhibit the growth of fir wood volume, and the increase in the stock of the mixed forest is mainly caused by the increase in the volume of broad-leaved trees.

[0046] Stand productivity was used to evaluate the relationship between Chinese fir and broad-leaved tree species in mixed Chinese fir / broad-leaved tree stands.

[0047] The stand productivity of mixed fir / broad-leaved forests is the actual volume growth of the mixed forest divided by the expected volume growth. When the value is greater than 1, the actual volume growth of the mixed forest is due to the mutual benefit or complementary relationship between fir and broad-leaved trees, resulting in an increase in fir production; if the value is less than 1, the actual volume growth of the mixed forest is due to interspecific competition between fir and broad-leaved trees, resulting in a decrease in fir production.

[0048] Furthermore, if the actual volume growth of fir and broad-leaved trees in a mixed forest is greater than 1, then there is a mutually beneficial relationship between the two species, and the two promote each other and jointly increase the forest stand volume. In this case, the broad-leaved tree species is the best broad-leaved tree species for mixing with fir. If the actual volume growth of fir in a mixed forest is greater than 1, and the actual volume growth of broad-leaved trees is less than 1, then there is a complementary relationship between fir and broad-leaved trees, and it can be confirmed that the broad-leaved tree species has created favorable conditions for the growth of fir, but its own growth is inhibited by fir, and the increase in the actual volume growth of the mixed forest is caused by the growth of fir. This type of tree species that can form a complementary relationship with fir can also be used as a secondary suitable tree species for mixing with fir.

[0049] By comparing the volume growth of individual fir trees in mixed fir / broadleaved forests and pure fir forests, we can determine whether broadleaved species mixed with fir will promote the volume growth of fir trees, but we cannot guarantee whether the yield of standard timber species after fir wood processing will increase accordingly. Only when the yield of standard timber species increases can the utilization rate of wood be improved. Therefore, it is necessary to compare the yield of standard timber species of fir in mixed fir / broadleaved forests and pure fir forests.

[0050] 3. Comparison of the yield of standard species of Chinese fir in mixed Chinese fir / broadleaved forests and that of pure Chinese fir forests

[0051] (1) According to the standard for standard Chinese fir timber, standing Chinese fir trees are divided into three types: small-diameter timber [8 cm ≤ DBH < 14 cm], medium-diameter timber [16 cm ≤ DBH < 20 cm], and large-diameter timber (DBH ≥ 22 cm);

[0052] (2) Based on the fir wood volume table, calculate the volume of the three types of fir wood species;

[0053] (3) Dividing the volume of small-diameter wood, medium-diameter wood and large-diameter wood by the stand volume, we can obtain the standard wood yield rate of small-diameter wood, medium-diameter wood and large-diameter wood;

[0054] (4) Compare the yield of large-diameter, medium-diameter, and small-diameter standard wood species in mixed fir / broadleaved forests and pure fir forests. If the yield of large-diameter and medium-diameter standard wood species in mixed fir / broadleaved forests increases by 18% and 30% respectively, it means that mixed planting has indeed promoted the yield of fir and improved the efficiency of fir wood utilization.

[0055] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0056] The status index of Chinese fir refers to the average height of dominant Chinese fir trees in a 20-year-old Chinese fir forest. When the height of dominant trees is between [13.1, 14.9) m, the status index of the forest is 14; when the height is between [15.1, 16.9) m, the status index of the forest is 16; when the height is between [17.1, 18.9) m, the status index of the forest is 18; and so on.

[0057] If the age of the Chinese fir forest is not 20 years, the Chinese fir status index is calculated using the method shown in "Compilation and Application of the National Chinese fir (seedling forest) status index table" by the Chinese fir cultivation research collaboration group of the fourteen southern provinces (regions) (1982).

[0058] For afforestation land where no fir forests have been planted in the past, but the quality of the afforestation land needs to be evaluated during afforestation, the "multi-level status index method" is used to calculate the status index.

[0059] Example 1

[0060] In the spring of 1999, mixed planting of fir and broad-leaved trees was carried out in the clear felled site of fir in Qingyuan, Zhejiang. The fir status index of the afforestation site was 16, and local native broad-leaved tree species such as Choerospondias australis, Schima superba, Sassafras chinensis, Phoebe chekiangensis and Cinnamomum camphora were selected and planted in mixed planting with fir in rows, with a planting density of 2.0m×1.5m. At the same time, a pure fir forest was established as a control for yield measurement.

[0061] In the spring and autumn of 1999 and 2000, forest cultivation was carried out respectively, and shrubs, herbs and vines that affected the growth of afforestation seedlings were removed.

[0062] In the spring of 2008, when the mixed fir / broad-leaved forest was 9 years old, adjacent fir and broad-leaved trees were used as a thinning unit, and thinning was carried out by comparing the growth conditions of fir and broad-leaved trees between rows and between plants. After thinning, the retained density of plants in the mixed forest was about 50% of the afforestation density.

[0063] In the spring of 2024, when the mixed fir / broadleaved forest reached the age of 25 years in the rotation period, various growth indicators were measured, and growth indicators such as the accumulation, volume growth of individual trees, and the output of standard species of fir and pure forests of different tree species and mixed fir / broadleaved forests were calculated. At the same time, the relative productivity of mixed fir / broadleaved forests was calculated using the actual volume growth and expected volume growth, and the promotion / inhibition effect of interspecific relationships between fir and different broadleaved trees on yield was quantified. The results are shown in Tables 1 and 2.

[0064] Table 1 Comparison of volume, volume growth per tree and output of standard species in pure forests of fir and broad-leaved trees and their mixed forests

[0065]

[0066]

[0067] Table 2 Interspecific interactions between Chinese fir and broad-leaved trees and their effects on yield

[0068]

[0069] From Table 1 and Table 2, it can be seen that the forest volume of pure fir forest is the lowest, with the small-diameter timber yield exceeding 70%, the medium-diameter timber yield less than 20%, and the large-diameter timber yield 0; the forest volume of fir mixed with several broad-leaved tree species, such as Phoebe chekiangensis, Cinnamomum camphora, Choerospondias australis, and Sassafras, will be increased to varying degrees. When fir is mixed with Choerospondias australis and Sassafras, which have a competitive relationship, the small-diameter timber yield exceeds 50%, the medium-diameter timber yield does not exceed 25%, and the large-diameter timber yield is within 9%; when fir is mixed with Cinnamomum camphora, which has a complementary relationship, the small-diameter timber yield ratio is reduced to 25%, the medium-diameter timber yield ratio exceeds 50%, and the large-diameter timber ratio is increased to more than 18%; when fir is mixed with Phoebe chekiangensis, which has a mutually beneficial relationship, the small-diameter timber yield ratio is reduced to 10%, the medium-diameter timber yield ratio is close to 60%, and the large-diameter timber yield ratio reaches more than 30%. This shows that mixed planting of Chinese fir with mutually beneficial broad-leaved species will significantly increase forest yield and the recovery rate of large and medium-sized timber species; mixed planting of Chinese fir with complementary broad-leaved species is second best, and mixed planting with competing broad-leaved species has the worst effect.

[0070] In summary, there is a competitive relationship between Chinese fir and Choerospondias axillaris, Chinese fir and Sassafras chinensis, a complementary relationship between Chinese fir and Cinnamomum camphora, and a mutually beneficial relationship between Chinese fir and Phoebe chekiangensis. This indicates that mixed planting of Chinese fir, Cinnamomum camphora and Phoebe chekiangensis can increase the timber yield and the recovery rate of large and medium-sized timber species in Chinese fir plantations.

[0071] Example 2

[0072] In the spring of 2004, mixed planting of Chinese fir and broad-leaved trees was carried out on abandoned broad-leaved land in southern Jiangxi. The status index of Chinese fir in the afforestation site was 18, and the native broad-leaved tree species of southern subtropical areas, such as Castanopsis hystrix, Phoebe macrantho, Quercus acutissima and Eucalyptus, were selected and mixed with Chinese fir in rows, with a planting density of 2.0m×2.0m. At the same time, a pure Chinese fir forest was established as a control for yield measurement.

[0073] In late spring and early summer of 2004, 2005 and 2006, the understory vegetation was completely mowed to remove shrubs, herbs and vines that would affect the growth of afforestation seedlings.

[0074] In the autumn of 2014, when the mixed fir / broad-leaved forest was 8 years old, adjacent fir and broad-leaved trees were used as a thinning unit, and nursing thinning was carried out by comparing the growth conditions of fir and broad-leaved trees between rows and between plants. After thinning, the retained density of plants in the mixed forest was about 50% of the afforestation density.

[0075] In the spring of 2024, when the mixed Chinese fir / broad-leaved forest reached the age of 20 years in the rotation period, various growth indicators were measured, and growth indicators such as the accumulation, volume growth of individual trees, and the output of standard species of Chinese fir and pure forests of different tree species and Chinese fir / broad-leaved mixed forests were calculated. At the same time, the relative productivity of the mixed Chinese fir / broad-leaved forest was calculated using the actual volume growth and the expected volume growth, and the promotion / inhibition effect of the interspecific relationship between Chinese fir and different broad-leaved trees on yield was quantified. The results are shown in Tables 3 and 4.

[0076] Table 3 Comparison of volume growth, volume growth per tree and output of standard species in pure forests of Chinese fir and broad-leaved trees and their mixed forests

[0077]

[0078] Table 4 Interspecific interactions between Chinese fir and broad-leaved trees and their effects on yield

[0079]

[0080]

[0081] Tables 3 and 4 show that the volume of pure fir forests is the lowest, with a small-diameter timber yield of more than 70%, a medium-diameter timber yield of less than 15%, and a large-diameter timber yield of 0; the volume of pure fir forests is much smaller than that of mixed forests. In the mixed fir / broad-leaved tree forests, the volume of the mixed fir / eucalyptus forest with interspecific competition is the smallest, followed by the mixed fir / quercus acutissima forest with interspecific complementary relationships, and the mixed fir / castanum and fir / Phoebe macclurei forests with interspecific mutualistic relationships have the largest volume. At the same time, in the mixed fir and broad-leaved tree forests with interspecific mutualism, the yield rate of large-diameter timber exceeds 23%, the yield rate of medium-diameter timber exceeds 50%, and the yield rate of small-diameter timber is less than 20%; in the mixed fir and broad-leaved tree forests with interspecific complementarity, the proportion of large-diameter timber is close to 20%, the yield rate of small-diameter timber is slightly higher than 45%, and the yield rate of small-diameter timber reaches 30%; in the mixed fir and broad-leaved tree forests with interspecific competition, the proportion of large-diameter timber is only 4%, the yield rate of medium-diameter timber is less than 45%, and the yield rate of small-diameter timber exceeds 35%.

[0082] In summary, there is a competitive relationship between Chinese fir and Eucalyptus, a complementary relationship between Chinese fir and Quercus acutissima, and a mutually beneficial relationship between Chinese fir and Castanopsis hystrix, as well as Chinese fir and Phoebe macclure. This suggests that mixed planting of Chinese fir with Quercus acutissima, Castanopsis hystrix, and Chinese fir and Phoebe macclure can increase the timber yield and the recovery rate of large and medium-sized timber species in Chinese fir plantations.

[0083] From the above examples, it can be seen that the present invention provides a method for selecting broad-leaved tree species suitable for interplanting with Chinese fir. Interplanting Chinese fir with broad-leaved tree species selected by the method can increase the wood yield of Chinese fir plantations and the yield rate of large and medium-sized timber species.

[0084] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for screening broad-leaved tree species suitable for interplanting with Chinese fir, characterized in that: The following steps are involved: S1. Select afforestation land with a fir status index of 14 or above; S2. Mix Chinese fir and broad-leaved trees for afforestation, and simultaneously establish a pure Chinese fir forest as a control for yield measurement; S3. During the growth of mixed fir / broadleaved forests, if the canopy of broadleaved trees shades the canopy of adjacent fir trees by more than 1 / 3, thinning should be performed on both the fir and broadleaved trees; S4. Determine the rotation period based on the status index of Chinese fir trees in the afforestation land; S5. Compare the stock accumulation of mixed fir / broadleaved forests and pure fir forests after felling during the rotation period; If the stock of the mixed fir / broad-leaved forest is less than that of the pure fir forest, exclude the mixed afforestation of the broad-leaved tree species with fir; if the stock of the mixed fir / broad-leaved forest is greater than that of the pure fir forest, continue to make the following comparison: (1) Compare the timber volume growth of individual Chinese fir trees in mixed Chinese fir / broadleaved forests and that of pure Chinese fir forests; (2) To compare the yield of standard species of Chinese fir in mixed Chinese fir / broadleaved forests with that in pure Chinese fir forests; If the timber volume growth of individual Chinese fir trees in a mixed forest is greater than that of a pure Chinese fir forest, and the yield of large-diameter and medium-diameter Chinese fir species in a mixed Chinese fir / broad-leaved tree forest is increased by 18% and 30% respectively compared with that in a pure Chinese fir forest, then the broad-leaved tree species is determined to be suitable for mixing with Chinese fir.

2. The method according to claim 1, characterized in that The afforestation land described in S1 is a habitat that can meet the needs of local native broad-leaved tree species to complete their life cycle.

3. The method according to claim 1, characterized in that The mixed planting method of fir and broad-leaved trees is row-shaped mixing, with the spacing between fir and broad-leaved trees being 2.0 to 2.5 m, and the spacing between plants within a row being 1.5 to 2.0 m.

4. The method according to claim 1, characterized in that: When thinning, treat adjacent fir and broad-leaved trees as a thinning unit. By comparing between rows and plants, cut down small trees and keep large ones, cut down inferior trees and keep superior ones, and take care of them evenly. After thinning, the retained density of plants is 45% to 50% of the initial afforestation density.

5. The method according to claim 1, characterized in that If the status index of Chinese fir in the afforestation land is 18 or above, the rotation period is 15 to 20 years; if the status index of Chinese fir in the afforestation land is 16, the rotation period is 20 to 25 years; if the status index of Chinese fir in the afforestation land is 14, the rotation period is 25 to 30 years.

6. The method according to claim 1, characterized in that The large-diameter timber is Chinese fir with a breast diameter ≥ 22 cm, the medium-diameter timber is Chinese fir with a breast diameter of 16 cm ≤ and < 20 cm, and the small-diameter timber is Chinese fir with a breast diameter of 8 cm ≤ and < 14 cm.

7. Use of the method according to any one of claims 1 to 6 in Chinese fir afforestation.

8. Use of the method according to any one of claims 1 to 6 in increasing the timber yield of a Chinese fir plantation.

9. Use of the method according to any one of claims 1 to 6 in improving the yield of standard timber species in Chinese fir plantations.

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