Cultivation method for improving diversity of plants under moso bamboo forest

Abstract

The invention discloses a cultivation method for improving the diversity of plants under a moso bamboo forest, which comprises the following steps: comprehensively cutting moso bamboo individuals with the bamboo age of more than 3 degrees, and adjusting the stand density of the moso bamboo forest; after thinning, shade-tolerant nitrogen-fixing functional plants are introduced into the moso bamboo forest in a broadcast sowing mode, and favorable conditions are provided for nitrogen turnover; microbial agent gel composed of nitrobacteria, nitrite bacteria and nitrogen-fixing bacteria is added into the moso bamboo forest, the protection effect on strains is better achieved, the content of nitrate nitrogen in the moso bamboo forest is increased, and growth of moso bamboo is facilitated. According to the method, growth and diversity of shrubs and herbaceous plants under the moso bamboo forest are rapidly recovered, the soil fixing and water containing performance of the moso bamboo forest is greatly improved, health and stability of an ecological system are promoted, and the ecological service function of the moso bamboo forest is maintained.

Description

Technical Field

[0001] The present invention belongs to the technical field of moso bamboo forest cultivation, and particularly relates to a cultivation method for improving the plant diversity under moso bamboo forests. Background Art

[0002] Moso bamboo (Phyllosatachys edulis) is the most important bamboo species with the largest cultivation area in China, and has significant economic and ecological benefits. The ninth national forest resources inventory shows that the total area of bamboo forests in China is 6.4116 million hectares, of which the area of moso bamboo forests reaches 4.6778 million hectares, accounting for 72.96% of the total area of bamboo forests in the country. Since the 1970s, people have pursued an intensive management method of density, uniformity, height, strength, and evenness, transformed moso bamboo mixed forests into pure moso bamboo forests, cut down the understory shrubs and grasses, and implemented high-intensity management, resulting in the gradual decline of moso bamboo forests. However, in recent years, due to the decline in its economic benefits and the increase in artificial management costs, a large number of moso bamboo forests are in a state of extensive management or no management, making the degradation of moso bamboo forests more prominent. Therefore, there are a large number of low-quality and low-efficiency moso bamboo forests, mainly manifested as growth decline, decreased shoot yield, decreased thickness of new bamboo, low quality, low plant diversity under the forest, serious soil erosion, and low ecological function. Therefore, it is imperative to adjust the stand structure of existing low-quality and low-efficiency moso bamboo forests and combine appropriate management to simply and quickly restore the plant diversity under pure moso bamboo forests and improve the stability and ecological service function of the stand. At present, there is almost no corresponding research and practice specifically for improving plant diversity in the management of bamboo forest ecosystems. In forestry production, it is generally believed that the use of mixed planting can improve biodiversity, but this management method has certain limitations, such as high technical requirements for operation, large management difficulty, high cost, etc., and is often only applicable to the construction and management of shelter forests. For scattered bamboo species represented by moso bamboo, it has a strong characteristic of expanding to the surrounding forests and gradually forms a pure forest structure with moso bamboo as the single dominant species, resulting in a decline in the diversity of understory shrubs and grasses. Especially in the current situation where bamboo forests are gradually out of management, the low biodiversity and weak ecological service capacity of bamboo forests are becoming more prominent. Although the creation of mixed forests of Phyllostachys pubescens and other tree species has certain applications in production, over time, the structure of artificially created mixed forests of Phyllostachys pubescens is not stable. Because a large number of studies have shown that Phyllostachys pubescens has the characteristic of repelling the growth of other plants. Especially for the growth of those arbors or large shrubs, only some shade-tolerant low-growing shrubs and herbaceous plant species are less affected, and ultimately the stand structure will be simplified. In production, it has indeed proved the above theoretical results, that is, the structure of the mixed forest of Phyllostachys pubescens is not stable and will gradually succeed to a pure forest of Phyllostachys pubescens over time. Therefore, it is not advisable to improve the plant diversity in Phyllostachys pubescens forests by creating mixed forests. According to the growth characteristics and nutrient utilization characteristics of Phyllostachys pubescens, feasible management methods must be taken targeted to effectively improve the plant diversity under Phyllostachys pubescens forests and improve the comprehensive benefits of Phyllostachys pubescens forests. Summary of the Invention

[0003] Technical problems to be solved: The purpose of the present invention is to reduce the stand density of Phyllostachys pubescens forests by thinning out the Phyllostachys pubescens individuals with a bamboo age of more than 3 years, so as to improve the light and microclimate in the forest. Combined with sowing the shade-loving and nitrogen-fixing plant Desmodium podocarpum, the nitrogen supply in the forest soil is increased. Adding an aerogel made of microbial inoculant, which is environmentally friendly, can increase the nitrate nitrogen content in Phyllostachys pubescens forests, create favorable conditions for the colonization and regeneration of nitrate nitrogen-loving plants, and is beneficial to the growth of Phyllostachys pubescens. Through the above comprehensive measures, the growth and diversity of shrubs and herbaceous plants under Phyllostachys pubescens forests can be quickly restored within 1-2 years, and the soil and water conservation performance of Phyllostachys pubescens forests can be greatly improved, promoting the health and stability of the ecosystem and maintaining the ecological service function of Phyllostachys pubescens forests.

[0004] Technical solution: A cultivation method for improving the plant diversity under Phyllostachys pubescens forests, which is characterized by specifically including the following steps: S1. Adjustment of the stand density of Phyllostachys pubescens forests: Completely cut down the Phyllostachys pubescens individuals with a bamboo age of more than 3 years, and the reserved density is maintained at 2000-2400 plants / hm 2 , and the canopy density of the Phyllostachys pubescens forest after logging is 50%-60%; S2. Introduction of shade-tolerant and nitrogen-fixing functional plants: In the spring of the year after thinning, introduce shade-tolerant nitrogen-fixing functional plants into the Phyllostachys pubescens forest by sowing; S3. Application of the gel loaded with composite microbial inoculant: Apply the gel loaded with composite microbial inoculant to the soil of the Phyllostachys pubescens forest. Further, in step S1, the logging time is from November to January of the following year, and thinning is carried out every 3-4 years. Further, the shade-tolerant nitrogen-fixing plants in step S2 include Desmodium podocarpum, Cassia tora, Medicago sativa, Astragalus sinicus, and Lotus corniculatus. Further, the preparation method of the gel loaded with composite microbial inoculant in step S3 is as follows: S31: Weigh a certain amount of polyvinyl alcohol and sodium alginate, mix them with water, and heat to completely dissolve them. S32: Cool the dissolved solution to room temperature, add the prepared composite microbial inoculum in a certain proportion, mix evenly, then suck the mixture into a syringe and slowly drop it into the CaCl₂ solution to form small balls. S33: Immerse the formed small balls in the CaCl₂ solution, place them at 4°C for crosslinking for 24 hours, then take them out, wash them with distilled water multiple times, and place them in a petri dish to dry to obtain the gel loaded with the composite microbial inoculum. Further, the composite microbial inoculum is nitrobacteria, nitrosobacteria, and nitrogen-fixing bacteria. Further, the nitrobacteria is Nitrobacter winogradskyi, the nitrosobacteria is Nitrosomonas, and the nitrogen-fixing bacteria is Clostridium pasteurianum. Further, the preparation method of the composite microbial inoculum is as follows: Cultivate nitrobacteria, nitrosobacteria, and nitrogen-fixing bacteria respectively according to the conventional culture medium until the OD of the bacterial liquid concentration 600 reaches 0.3, 0.2, and 1 respectively, and then mix the cultivated bacterial liquids according to the ratio of Nitrobacter winogradskyi:Nitrosomonas:Clostridium pasteurianum of 2:2:1. Further, the conditions for applying the gel in step S3 are as follows: within the circumference range with a radius of 3 cm centered on the bamboo shoot, at a soil depth of 2 cm. Beneficial effects: 1. By regularly cutting the bamboo forest in the present invention, the lighting conditions in the bamboo forest are greatly improved and the microclimate in the forest is improved, creating favorable climatic conditions for the regeneration of understory vegetation. 2. By introducing shade-tolerant nitrogen-fixing functional plants in the present invention, the nitrogen content and nitrogen turnover rate of the soil in the bamboo forest are increased, thereby accelerating the colonization and regeneration of understory shrubs and herbs in the bamboo forest, especially the colonization and regeneration of nitrate-loving tree species. 3. In the present invention, a microbial inoculum gel is added to the soil of the bamboo forest. The microbial inoculum is composed of nitrobacteria, nitrosobacteria, and nitrogen-fixing bacteria. Nitrobacteria and nitrosobacteria produce nitrate nitrogen through nitrification, improving the problem of low nitrate nitrogen content in the soil of the bamboo forest, and nitrogen-fixing bacteria are beneficial to the growth of bamboo. 4. Making the microbial inoculum into the form of a gel can avoid the adverse effects of low environmental temperature on the activity of bacteria, and is more conducive to restoring the growth and diversity of shrubs and herbs under the bamboo forest. Description of the drawings Figure 1 It is a photo of a deserted bamboo forest. Figure 2 It is a photo of the bamboo forest after thinning, introducing nitrogen-fixing functional plants, and injecting microbial inoculum gel. Specific embodiments The present invention will be further described below in conjunction with the accompanying drawings and embodiments. The following embodiments are explanations of the present invention, and the present invention is not limited to the following embodiments: Example 1 The preparation method of the gel loaded with composite microbial agents is as follows: S11: Prepare a 10% polyvinyl alcohol solution and a 0.5% sodium alginate solution respectively, and mix these two solutions evenly; S12: Add the prepared composite microbial agent according to the ratio of the above mixed solution to the composite microbial agent of 1:2. The composite microbial agent is composed of Nitrobacter winogradskyi, Nitrosomonas europaea, and Clostridium pasteurianum. Nitrobacter winogradskyi, Nitrosomonas europaea, and Clostridium pasteurianum are respectively cultured according to the conventional culture medium until the OD of the bacterial liquid concentration 600 reaches 0.3, 0.2, and 1 respectively. Then, the cultured bacterial liquids are mixed according to the ratio of Nitrobacter winogradskyi:Nitrosomonas europaea:Clostridium pasteurianum of 2:2:1 to form a composite microbial agent. After mixing the polyvinyl alcohol, sodium alginate solution, and microbial agent evenly, the mixture is sucked into a syringe and slowly dropped into a 2% CaCl2 solution to form small balls; S13: Immerse the formed small balls in a 2% CaCl2 solution and place them at 4°C for crosslinking for 24 hours, then take them out, wash them with distilled water multiple times, and place them in a petri dish to dry to obtain the gel loaded with the composite microbial agent. Example 2 The experimental object is the Phyllostachys edulis forest in Liangkeng Village, Changting County, Fujian Province. The start time of the experiment is 2015, and it specifically includes the following steps: S1. Investigate the natural conditions of the Phyllostachys edulis forest of the implementation object: Measure the average stand density, average breast diameter, and stand canopy density of the abandoned Phyllostachys edulis forest without management. S2. Adjust the stand density of the Phyllostachys edulis forest: Completely cut down the Phyllostachys edulis individuals with a bamboo age of more than 3 years, and maintain the retention density at 2000 plants / hm 2 , and the canopy density of the Phyllostachys edulis forest after felling is 50%; S3. Introduce shade-tolerant nitrogen-fixing functional plants: In the spring of the next year after thinning (March 2016), introduce 102 shade-tolerant nitrogen-fixing functional plants, Cassia tora, into the Phyllostachys edulis forest by sowing; S4. Apply the microbial agent gel: Apply the microbial agent gel to the soil of the Phyllostachys edulis forest. The application range is a circle with a radius of 3 cm centered on the Phyllostachys edulis, and the depth is 2 cm of the soil layer. Through the investigation of the natural conditions of the Phyllostachys edulis forest of the implementation object, the results show that the average stand density of the abandoned Phyllostachys edulis forest without management reaches 5687 plants / hm 2 , the average breast diameter is about 9.05 cm, and the stand canopy density reaches 0.95. For these low-efficiency Phyllostachys edulis forests without management, the diversity of understory plants is low, and soil and water loss under the forest is relatively serious (see the appendixFigure 1 and Table 1). Since 2015, the abandoned and low-efficiency moso bamboo forests have been thinned according to the method described in this document. Cassia seeds are sown in the thinned moso bamboo forests, and then microbial inoculant gels are applied in the moso bamboo forests. The results show that Cassia occupies the dominant ecological niche under the moso bamboo forests 1 - 2 years after treatment. However, over time, the number and abundance of other shrubs and herbs under the forest gradually increase, greatly increasing the plant diversity under the moso bamboo forests (see Appendix Figure 2 and Tables 1, 2, and 3). At the same time, the soil and water conservation performance of the moso bamboo forest stands has also been improved. Table 1 Table 2 Table 3 The specific index explanations in Table 3 are as follows: Simpson index: The Simpson index reflects the relative abundance of different species in a sample. The larger the Simpson index value, the lower the community diversity and the more uneven the community. Shannon index: It is an index to measure the species richness and evenness in an ecosystem. The higher the Shannon index, the more evenly distributed the relative abundance of species. Chao index: It is a diversity estimation index based on the distribution of species individual abundances in a sample. The higher the Chao index, the greater the species richness. Pielou evenness index: It is used to measure the relative species richness in a community and represents the distribution evenness of species. The higher the Pielou evenness index, the more evenly distributed the species. As described above, it is only the preferred embodiment of the present invention and does not impose any form of limitation on the present invention. Any person skilled in the art can make many possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above, or modify it into an equivalent embodiment with equivalent changes. Therefore, any simple modification, equivalent replacement, equivalent change, and modification made to the above embodiments based on the technical essence of the present invention without departing from the technical solution of the present invention still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A cultivation method for improving the plant diversity under Moso bamboo forests, characterized in that, Specifically, it includes the following steps: S1. Adjustment of stand density of Moso bamboo forest: Completely cut down Moso bamboo individuals over 3 years old, and maintain the retention density at 2,000 - 2,400 plants / hm 2 , and the canopy density of the Moso bamboo forest after felling is 50% - 60%; S2. Introduce shade-tolerant nitrogen-fixing functional plants: In the spring of the year following the thinning, introduce shade-tolerant nitrogen-fixing functional plants into the Phyllostachys edulis forest by sowing. S3. Apply the gel loaded with composite microbial agents: Apply the gel loaded with composite microbial agents to the soil of the Phyllostachys edulis forest.

2. The cultivation method for improving the plant diversity under the Phyllostachys edulis forest according to claim 1, characterized in that, In step S1, the logging time is from November to January of the next year, and thinning is carried out every 3 - 4 years.

3. The cultivation method for improving the plant diversity under the bamboo forest according to claim 1, characterized in that, In step S2, the shade-tolerant nitrogen-fixing plants include Desmodium podocarpum var. oxyphyllum, Cassia tora, Medicago sativa, Astragalus sinicus, and Lotus corniculatus.

4. A cultivation method for improving the plant diversity under a moso bamboo forest according to claim 1, characterized in that, The preparation method of the gel loaded with composite microbial agents in step S3 is as follows: S31: Weigh a certain amount of polyvinyl alcohol and sodium alginate, mix them with water, and heat to completely dissolve them. S32: Cool the dissolved solution to room temperature, add the prepared composite microbial agents in a certain proportion, mix evenly, suck the mixture into a syringe, and slowly drop it into the CaCl2 solution to form small balls. S33: Immerse the formed small balls in the CaCl2 solution, place them at 4°C for crosslinking for 24 hours, then take them out, wash them with distilled water multiple times, and place them in a petri dish to dry to obtain the gel loaded with composite microbial agents.

5. The cultivation method for improving the plant diversity under the Phyllostachys edulis forest according to claim 4, characterized in that, The composite microbial agents are nitrobacteria, nitrite bacteria, and nitrogen-fixing bacteria.

6. A cultivation method for improving the plant diversity under a moso bamboo forest according to claim 5, characterized in that, The nitrobacteria is Nitrobacter winogradskyi, the nitrite bacteria is Nitrosomonas europaea, and the nitrogen-fixing bacteria is Clostridium pasteurianum.

7. A cultivation method for improving the plant diversity under Moso bamboo forests according to claim 4, characterized in that, The preparation method of the composite microbial agent is as follows: Nitrobacter, Nitrosomonas and Azotobacter are respectively cultured according to a conventional culture medium until the OD of the bacterial liquid concentration 600 reaches 0.3, 0.2 and 1 respectively, and then the cultured bacterial liquids are mixed according to the ratio of Nitrobacter winogradskyi: Nitrosomonas: Clostridium pasteurianum of 2:2:

1.

8. A cultivation method for improving the plant diversity under a moso bamboo forest according to claim 1, characterized in that, The conditions for applying the gel in step S3 are as follows: within a circular range with a radius of 3 cm centered on the plant, at a soil depth of 2 cm.

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