Method for expanding propagation and conservation of thermophilic rare mangrove black plum in marginal area

Abstract

The invention discloses a method for expanding propagation and conservation of thermophilic rare mangrove black plum in a marginal area. According to the method, a waste salt pan (field) with sufficient illumination in the northern marginal area is selected, and a series of measures such as soil temperature increasing and nutrient increasing, close planting, naphthylacetic acid and gibberellin mixed solution spraying and straw heat preservation (winter) are taken, so that a natural breeding mode with a thermophilic environment and obligate outcrossing characteristics is built, and the growth of mangrove prunus salicina plants and the stability of communities are accelerated. The method plays an important role in the aspects of rescue retention of rare and endangered herminium cerasus germplasm resources, maintenance of herminium cerasus germplasm resources and genetic diversity and the like, also provides possibility for northward migration, introduction and propagation of herminium cerasus, and ensures continuous and sustainable growth of herminium cerasus in marginal areas.

Description

Technical Field

[0001] This invention belongs to the field of rare plant population construction and restoration technology, specifically relating to a method for propagating and conserving thermophilic rare mangrove plum trees in marginal areas. Background Technology

[0002] Olive plum ( Lumnitzera racemosa Willd *Prunus campestris* is a thermophilic, narrowly distributed mangrove species, mainly found in Hainan, Guangdong, and Guangxi provinces of my country, with a higher concentration around latitude 20°. The slow regeneration rate of *Prunus campestris* in natural forests and the obstacles to sexual reproduction (such as low pollination rates and difficulties in seed germination or seedling establishment) have led to a gradual decline in its population, resulting in its increasing endangerment.

[0003] In 2010, Liao Baowen, a researcher at the Chinese Academy of Forestry, discovered small patches of *Prunus camphora* (Chinese olive plum) in Pinghai Town, Huidong County. In 2013, Peng Yisheng and colleagues from Sun Yat-sen University conducted a comprehensive survey of mangroves along the coast of Huizhou City, finding that *Prunus camphora* populations were mainly distributed in Pinghai Town and Yanzhou Island in Huangbu Town, with scattered distributions near Doutou Village in Huangbu Town. Based on field surveys and literature records, the coastal area of ​​Huidong County in Huizhou City, Guangdong Province, represents the northernmost edge of the natural distribution of *Prunus camphora* in my country and even across Eurasia.

[0004] Researchers conducted a field survey of the *Prunus mume* population along the coast of Huidong County, Huizhou City, Guangdong Province. Compared with historical records, the distribution area of ​​*Prunus mume* population in the coastal area of ​​Huidong County has shrunk, and some areas no longer have *Prunus mume* populations (such as Doutou Village and Yanzhou Island). In order to strengthen the protection of this rare and endangered mangrove plant population and its survival in the northern edge area, it is urgent to carry out propagation and conservation work for *Prunus mume* population.

[0005] Currently, although there are relevant patents reporting on the collection, seedling cultivation, and seedling care of *Prunus armeniaca* seeds (CN110089337 B and CN 106613645 B), there are no reports on the propagation, afforestation, conservation, and community construction and restoration of *Prunus armeniaca*. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a method for the propagation and conservation of the thermophilic rare mangrove plum (Prunus mangrove) in marginal areas. This invention selects abandoned salt fields (sites) with ample sunlight in the northern marginal areas and employs a series of measures, including soil warming and nutrient enhancement, dense planting, spraying with a mixture of naphthaleneacetic acid and gibberellin, and straw insulation (in winter), to create a thermophilic environment and a natural propagation method that promotes the obligate crossbreeding characteristics of the mangrove plum, thereby accelerating the growth of the mangrove plum and stabilizing the community. This method allows for the rapid establishment and restoration of the mangrove plum community.

[0007] The objective of this invention is achieved through the following technical solution: A method for propagating and conserving the rare thermophilic mangrove plum in marginal areas includes the following steps: S1. Site Selection: Select marginal areas with historical or current distribution of *Prunus armeniaca*, and abandoned salt fields or salt drying sites located in estuaries or inner bays with sufficient sunlight as afforestation sites; S2, Land preparation: ① The elevation of the afforestation plots was adjusted by filling or excavating to make the plots below the mean sea level; ②After elevation adjustment, the land is compacted to achieve a soil liquid limit index of 0.3 to 0.7; ③ After compacting the soil, spread a layer of native soil, loam, and semi-decomposed garden waste on top. Mix the native soil, loam, and semi-decomposed garden waste in a ratio of 0.8-1.2:0.8-1.2:0.8-1.2, and spread the mixture to a thickness of 0.2-0.3m. (Adding loam increases root aeration and water retention, while adding semi-decomposed garden waste increases nutrients and warms the soil, which can promote rapid root growth.) ④ Construct waterways and tidal channels to connect the land plot with the external tides; S3. Afforestation and planting: Medium to large seedlings are used for planting, with a seedling height of 100-150 cm and a planting density of 0.5 m × 0.5 m to 0.5 m × 1 m (because the propagation system of the olive plum is obligate crossbreeding, it is necessary to plant the olive plum densely to facilitate its natural propagation). S4. Afforestation and Maintenance: ① Within one month after afforestation, use fresh water for sprinkler irrigation, 3 to 5 times a day. Within two to three months after afforestation, use fresh seawater for sprinkler irrigation, 1 to 2 times a day (in order to maintain soil and air humidity and ensure the water needs of the roots and leaves of the olive plum plant). ② Within 5 months after afforestation, spray naphthaleneacetic acid and gibberellin on the trunk in a ratio of 4 to 6:1, and spray 3 to 5 times per month (since the olive plum is a slow-growing tree species, applying the mixture in this ratio can accelerate the horizontal and vertical growth of the olive plum trunk). ③ In winter, lay straw organic matter on the afforestation plots, with a thickness of about 0.1 to 0.15 m (to keep warm and prevent the impact of winter cold waves). ④ Timely replanting of plots with a survival rate below 70% or uneven distribution (to ensure the formation and natural reproduction of the olive plum community); S5. Post-conservation: Carry out beach closure and conservation, set up protective nets around the afforestation area with a height of 2-3 m, and set up warning signs to prohibit any personnel and vessels from entering the mangrove area, and prohibit any form of fishing activities such as netting and digging; promptly clean up the afforestation area and anything entangled on the saplings; the beach closure and conservation period shall not be less than 3 years.

[0008] Furthermore, in step S2 ① after the elevation adjustment of the afforestation plot, the final elevation of the plot is 0.2 m below the mean sea level.

[0009] Furthermore, the original soil mentioned in step S2 ② is derived from the soil excavated in step ①.

[0010] Furthermore, the garden waste mentioned in step S2 ③ includes leaves and weeds.

[0011] Furthermore, the native soil, loam, and semi-decomposed garden waste described in step S2 ③ are mixed in a ratio of 1:1:1.

[0012] Furthermore, the paving thickness described in step S2, ③, is 0.2 m.

[0013] Furthermore, in step S2, ④, at least one waterway or tidal ditch shall be constructed for each afforestation plot.

[0014] Furthermore, in step S3, during the initial stage of afforestation, bamboo poles or other fixed objects are erected next to the young plum seedlings to mitigate the impact of wind and waves.

[0015] Furthermore, in step S4, ②, naphthaleneacetic acid and gibberellin are sprayed at a height of 0-3 cm from the ground on the tree trunk, with a mixing ratio of 5:1.

[0016] Furthermore, the items wrapped around the sapling in step S5 include, but are not limited to, debris, seaweed, and barnacles.

[0017] Furthermore, in step S5, the height of the protective net is 3 m.

[0018] Furthermore, in order to better protect and restore the *Prunus armeniaca* community and to promptly assess the effectiveness of *Prunus armeniaca* propagation and conservation, community growth indicators are monitored over a period of 3 to 5 years within the project implementation area.

[0019] Furthermore, the community growth indicators include at least one of the following: survival rate, retention rate, plant height, basal diameter, canopy closure, and understory regeneration (hypocotyl germination) rate.

[0020] Compared with the prior art, the present invention has the following advantages and effects: The value of the olive plum is very high. It can be used not only as building material and fuel, but also for food and medicinal purposes. Its leaves are edible, and its sap can treat oral thrush. Its chemical components have good anti-inflammatory, antifungal, and antihypertensive effects. However, due to the slow regeneration rate of olive plum forests and obstacles in sexual reproduction, it is gradually becoming endangered.

[0021] This invention has carried out a propagation and conservation project for the rare thermophilic mangrove plum in marginal areas. It plays an important role in the rescue preservation of rare and endangered germplasm resources, maintaining the germplasm resources and genetic diversity of mangrove plum, and also provides the possibility for the northward introduction and propagation of mangrove plum, ensuring the survival and sustainable growth of mangrove plum in marginal areas. Attached Figure Description

[0022] Figure 1 This is a site plan for the propagation and conservation project of *Prunus armeniaca* in the afforestation area.

[0023] Figure 2 This is a current status photo of the *Prunus armeniaca* propagation and afforestation project (taken in June 2025).

[0024] Figure 3 This is a picture of the current state of natural growth of native olive plum (taken in June 2025).

[0025] Figure 4 This is a comparison of the current status of the afforestation project of *Prunus camphora* (photographed in June 2025; some of the large plants in the picture are native *Prunus camphora*, not newly planted plants). Detailed Implementation

[0026] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0027] Unless otherwise specified, all raw materials and equipment used in this invention are commercially available products that can be directly purchased from the market.

[0028] In this embodiment of the invention, a propagation, afforestation and conservation project of the native tree species *Prunus camphora* was carried out in Huizhou City, Guangdong Province. The afforestation period was from May to July 2022, which strengthened the construction, restoration and research of *Prunus camphora* communities.

[0029] Example 1 Site selection: A demonstration mangrove forest of *Prunus armeniaca* will be planted on suitable afforestation tidal flats in Renping Peninsula, Huizhou City, covering an area of ​​66.67 hm². 2 The Renping Peninsula currently has scattered native *Prunus mume* species. Compared with historical data, the *Prunus mume* community has undergone significant degradation, with the total current distribution area of ​​*Prunus mume* less than 10 hectares. 2To facilitate the rapid establishment and restoration of the *Prunus camphora* community, abandoned salt fields in Pinghai Town and Huangbu Town were selected as areas for *Prunus camphora* propagation and afforestation, with a total afforestation area of ​​66.67 hm². 2 .

[0030] Site preparation: ① The elevation of the afforestation plots is measured. Since the plots are above the local average sea level, the soil is excavated to lower the elevation of the plots to within 0.2 m below the average sea level. ② After excavation, the soil is compacted to ensure that the soil liquid limit index is between 0.3 and 0.7. ③ After compaction, a layer of native soil (derived from the soil excavated in step ①), loam, and semi-decomposed garden waste (mainly leaves, weeds, etc.) is spread on top. The native soil, loam, and semi-decomposed garden waste are mixed in a 1:1:1 ratio and spread to a thickness of 0.2 m to achieve soil aeration, water retention, nutrient enhancement, and warming. ④ A tidal channel is constructed for each afforestation plot to connect it with the external tides.

[0031] Afforestation and Planting: Medium to large seedlings were used for planting. The seedlings came from the nursery of the Huangbu Town Olive Plum Conservation Center. The seedlings were 120 cm tall and planted at a density of 0.5 m × 0.5 m. The afforestation period was from May to July 2022. Bamboo poles and other fixed objects were erected next to the olive plum seedlings to reduce the impact of wind and waves.

[0032] Afforestation and Maintenance: ① To maintain soil and air humidity, use fresh water for irrigation 3-5 times a day for the first month after afforestation, and use fresh seawater for irrigation 1-2 times a day for the second to third month after afforestation; ② Since the olive plum is a slow-growing tree species, to accelerate its growth, spray naphthaleneacetic acid and gibberellin at the trunk 0-3 cm above the ground with a 5:1 ratio for the first 5 months after afforestation, spraying 3-5 times a month; ③ To prevent the impact of winter cold waves, lay straw on the afforestation site in winter with a thickness of 0.1 m; ④ To ensure the formation and natural reproduction of the olive plum community, replant in a timely manner on plots with a survival rate of less than 70% or uneven distribution.

[0033] Post-construction conservation: Implement beach closure and conservation measures, setting up protective nets 3 meters high around the afforestation area and placing warning signs. Entry of any personnel or vessels into the mangrove area is prohibited, as are any forms of fishing activities such as netting and digging. Promptly remove debris, seaweed, barnacles, etc., from the afforestation area and from saplings. The beach closure and conservation period will last for 3 years.

[0034] Community monitoring: In order to better protect and restore the *Prunus camphora* community and to timely assess the effectiveness of *Prunus camphora* propagation and conservation, community growth indicators will be monitored for three years in the project implementation area, including survival rate, retention rate, plant height, basal diameter, canopy closure, and understory regeneration (hypocotyl germination) rate.

[0035] Monitoring results: Through the propagation, afforestation, and conservation project of the native tree species *Prunus camphora*, monitoring data in June 2025 showed that the area of ​​the *Prunus camphora* community reached 66.67 hm². 2 The survival rate and retention rate both reached 85%, the plant height reached 180-250 cm (an increase of about 60-130 cm compared to the initial planting), the basal diameter reached 3-5 cm (an increase of about 2-3 cm compared to the initial planting), the canopy closure was greater than 65%, the understory regeneration (hypocotyl germination) rate was greater than 50%, and the natural propagation effect was obvious.

[0036] Comparative Example 1 During the same period as Example 1, existing native *Prunus camphora* were selected near the afforestation site in Sanzhou Village and allowed to grow naturally without any artificial intervention (named D1 plot); another afforestation site was selected in Donghai Village (named D2 plot), without the land preparation step ③ (nutrient enhancement and temperature increase) and the afforestation maintenance steps (humidification, temperature preservation, and rapid growth). The effects of the two plots were compared with those of the Example 1.

[0037] Plot D1 is native to the Chinese plum (Ligustrum lucidum), with a plum area of ​​approximately 0.1 hectares. 2 The plants are distributed in strips and have a growth history of 30-40 years. During this study, with increased protection and reduced human interference, no artificial measures were taken to allow them to grow and reproduce naturally. Compared to the baseline survey data in 2022, the monitoring data from June 2025 shows that the area of ​​*Prunus camphora* has decreased to some extent, mainly in the peripheral areas affected by surrounding vegetation. The understory regeneration (hypocotyl germination) rate is low, less than 5%, indicating poor natural propagation. Plant height increased by approximately 5 cm, while basal diameter growth was slow, less than 1 cm.

[0038] The afforestation area of ​​plot D2 is approximately 1 hectare. 2 Step ③ (nurturing and warming) and the afforestation maintenance steps (humidifying, warming, and promoting rapid growth) were not performed in this case. The planting density was 0.5 m × 1 m. The planting plants and timing were the same as in the previous example, using medium to large seedlings with a height of 120 cm. The afforestation time was also from May to July 2022. Other planting and maintenance work was the same as in the previous example. Monitoring data in June 2025 showed that the area of ​​the *Prunus armeniaca* community was the same as the afforestation area. The survival rate and retention rate were about 70%. Most of the plants were about 150 cm tall (about 30 cm taller than at the time of afforestation), with a base diameter of about 1-2 cm (about 1 cm taller than at the time of afforestation). The canopy closure was about 45%, and the understory regeneration (hypocotyl germination) rate was about 10%, indicating that the natural propagation effect was not obvious.

[0039] Figure 1 This is a site plan of the propagation project of olive and plum trees in Sanzhou Village, one of the afforestation plots.

[0040] Figure 2This is a current status photo of the *Prunus armeniaca* propagation and afforestation project (taken in June 2025).

[0041] Figure 3 This is a picture of the current state of natural growth of native olive plum (taken in June 2025).

[0042] Figure 4 This is a comparison of the current status of the afforestation project of *Prunus camphora* (photographed in June 2025; some of the large plants in the picture are native *Prunus camphora*, not newly planted plants).

[0043] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for propagating and conserving the rare thermophilic mangrove plum in marginal areas, characterized in that: Includes the following steps: S1. Site Selection: Select marginal areas with historical or current distribution of *Prunus armeniaca*, and abandoned salt fields or salt drying sites located in estuaries or inner bays with sufficient sunlight as afforestation sites; S2, Land preparation: ① The elevation of the afforestation plots was adjusted by filling or excavating to make the plots below the mean sea level; ②After elevation adjustment, the land is compacted to achieve a soil liquid limit index of 0.3 to 0.7; ③ After the soil is compacted, a layer of native soil, loam and semi-decomposed garden waste is laid on top. The native soil, loam and semi-decomposed garden waste are mixed in a ratio of 0.8~1.2:0.8~1.2:0.8~1.2, and the thickness of the layer is 0.2~0.3 m. ④ Construct waterways and tidal channels to connect the land plot with the external tides; S3. Afforestation and planting: Medium to large seedlings are used for planting, with a seedling height of 100–150 cm and a planting density of 0.5 m × 0.5 m to 0.5 m × 1 m. S4. Afforestation and Maintenance: ① Within one month after afforestation, use fresh water for sprinkler irrigation, 3 to 5 times a day. Within two to three months after afforestation, use fresh seawater for sprinkler irrigation, 1 to 2 times a day. ② Within 5 months after afforestation, spray naphthaleneacetic acid and gibberellin on the tree trunks in a mixture ratio of 4 to 6:1, and spray 3 to 5 times per month; ③ In winter, lay straw organic matter on the afforestation plots, with a thickness of about 0.1 to 0.15 m; ④ Replanting should be carried out in a timely manner in areas where the survival rate is less than 70% or the distribution is uneven; S5, Post-continuation care: Implement beach closure and conservation measures, setting up protective nets with a height of 2-3 meters around the afforestation area and setting up warning signs to prohibit any personnel or vessels from entering the mangrove area, and prohibit any form of fishing activities such as netting and digging; promptly clearing away anything in the afforestation area and tangled around the saplings; the beach closure and conservation period shall not be less than 3 years.

2. The method for propagation and conservation of thermophilic rare mangrove plum trees in marginal areas according to claim 1, characterized in that: In step S2, after the elevation of the afforestation plot is adjusted, the final elevation of the plot is 0.2 m below the mean sea level.

3. The method for propagation and conservation of thermophilic rare mangrove plum trees in marginal areas according to claim 1, characterized in that: The garden waste mentioned in step S2 ③ includes leaves and weeds; In step S2 ③, the native soil, loam, and semi-decomposed garden waste are mixed in a ratio of 1:1:

1. The paving thickness mentioned in step S2, ③ is 0.2 m.

4. The method for propagation and conservation of thermophilic rare mangrove plum trees in marginal areas according to claim 1, characterized in that: In step S2, ④, the construction of waterways and tidal ditches shall be carried out for each afforestation plot, with no less than one waterway and tidal ditch constructed.

5. The method for propagation and conservation of thermophilic rare mangrove plum trees in marginal areas according to claim 1, characterized in that: In step S3, during the initial stage of afforestation, bamboo poles are erected next to the young plum seedlings to mitigate the impact of wind and waves.

6. The method for propagation and conservation of thermophilic rare mangrove plum trees in marginal areas according to claim 1, characterized in that: In step S4, ②, naphthaleneacetic acid and gibberellin are sprayed on the tree trunk at a depth of 0-3 cm from the ground, with a mixing ratio of 5:

1.

7. The method for propagation and conservation of thermophilic rare mangrove plum trees in marginal areas according to claim 1, characterized in that: The items wrapped around the sapling in step S5 include, but are not limited to, debris, seaweed, and barnacles.

8. The method for propagation and conservation of thermophilic rare mangrove plum trees in marginal areas according to claim 1, characterized in that: In step S5, the height of the protective netting is 3 m.

9. The method for propagation and conservation of thermophilic rare mangrove plum trees in marginal areas according to any one of claims 1-8, characterized in that: In the method described, in order to better protect and restore the *Prunus armeniaca* community and to timely assess the effectiveness of *Prunus armeniaca* propagation and conservation, community growth indicators are monitored for 3 to 5 years within the project implementation area.

10. The method for propagation and conservation of thermophilic rare mangrove plum trees in marginal areas according to claim 9, characterized in that: The community growth indicators include at least one of the following: survival rate, retention rate, plant height, basal diameter, canopy closure, and understory regeneration rate.

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