Competition for Space of Individuals in the Model (Unit Cm)

Competition for simulation space in the model is shown in the figure

3.5. There, the dominant species has the strongest evolution and competition, and there are also manifestations of two species coexisting in the area.

Note: Indicates the pomegranate tree and its competitive influence zone. Denotes the sorrel cork tree and its competitive influence zone

Figure 3.5: Competition for space among individuals in the model (Unit cm)

Figure 3.6: Evolution of species distribution over time

The results of simulation model analysis of changes in species composition of species as well as biomass of each species and of the entire region are shown in figures 3.6 and 3.7.

Model analysis results show that species composition in the study area tends not to increase (2 species) without positive human impacts such as intercropping activities, creating space for regeneration. the natural ability of other tree species to adapt to the conditions of the region. For each specific species, it shows that the Trang species gradually decreases and stabilizes in the number of individuals in the standard plot, while the Sour species will gradually increase in the number of individuals but still accounts for a small proportion in the species structure.

Figure 3.7: Evolution of biomass value of species over time

The total biomass and biomass of species in the region both tend to decrease after 2010. With the current high density, the self-thinning process takes place continuously, and at this rate, opportunities for young trees arise. Self-regeneration is also not high, so the biomass of species in general will decrease. In addition, climatic factors changed due to global warming also have impacts on the growth and development of vegetation and therefore have direct and indirect effects on the biomass of each individual. species and total biomass per hectare of the whole region.

3.2.2. Proposed mangrove planning

* Legal basis for mangrove distribution planning

- Land Law 2003.

- Law on Forest Protection and Development 2004.

- Law on Environmental Protection 2005

- Decree No. 181/2004/ND-CP dated October 29, 2004 of the Prime Minister on the implementation of the 2003 Land Law and a number of guiding documents of the Ministry of Natural Resources and Environment.

- Decree No. 23/2006/ND-CP dated March 3, 2006 of the Government on implementing the Law on Forest Protection and Development.

- Decree 80/2006/ND-CP dated August 9, 2006 of the Government guiding the implementation of the Law on Environmental Protection.

- Decision No. 186/2006/QD - TTg dated August 14, 2006 of the Prime Minister on promulgating Forest Management Regulations.

- Decision No. 18/2007/QD-TTg dated February 5, 2007 of the Prime Minister approving the Vietnam Forestry Development Strategy for the period 2006-2020.

- Directive No. 38/2005/CT-TTg dated December 5, 2005 of the Prime Minister on reviewing and re-planning 3 types of forests (protection, special-use and production).

- Document No. 405/TTg-KTN dated March 16, 2009 of the Prime Minister approving the Mangrove Forest Restoration and Development Project for the period 2008 - 2015.

* Scientific basis for planning

- Towards sustainable development of mangrove forests in the study area

- The study area has suitable conditions for the submerged plants that already exist in the area in terms of: Flood level, soil, salinity...

- Towards developing species diversity and canopy diversity

- Ensure protection of coastline and dykes

- Support local economic development

* Mangrove forest planning plan at Xuan Thuy National Park

The conservation and development of mangrove forests in general and in the study area in particular need to be focused on developing both quality and quantity. As analyzed, in the context of climate change, the results show that there are many fluctuations in quantity (area of ​​mangrove forests). The first causes leading to that fluctuation are believed to be the effects of sea level rise as a result of climate change. However, existing in nature, the mangrove ecosystem as well as other ecosystems are affected by other interactions such as temperature,

salinity, extreme weather phenomena... and human impacts.

In addition to developing forests in the direction of sea reclamation, developing forests on abandoned aquaculture areas or expired contracts is a necessary task. However, this development direction requires a lot of time and effort because the aquaculture area's surface is not favorable for forest development, moreover, the immediate recovery of water surface area is not easy. Therefore, the research team proposes to direct forest development planning towards the pond area in a way that the state and people work together based on the ecological shrimp farming/aquaculture model. On the water surface area, over a 3-5 year cycle, gradually increase the ratio of forest area/water surface area for shrimp ponds. Set a goal that by the 15th or 20th year (depending on each specific locality) from the start of planning, the ratio of 60-70% of the current forest area/water surface area for aquaculture will be achieved. To implement this development planning direction, technical support is needed (specific research needs to be conducted in each region: what crops to plant, how to plant them, etc.) and funding (can be applied in different ways). Reduce the cost of water surface leasing, and be allowed to carry out contracting for the next term...

a. Mangrove forest distribution planning until 2030

b. Mangrove forest distribution planning by 2050

c. Mangrove forest distribution planning by 2100

According to research results, the mangrove area in Xuan Thuy National Park will gradually increase in planted and additional forest areas (in areas located in Giao Thien and Giao An communes), the protected area is the entire current area. status of mangrove forests in the national park's coastal areas (by 2020 there will be 4,732).

Table 3. 2: Planned area of ​​mangrove forests until 2100 in the study area

Type

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Based on the study of the region's ecological development model, a mangrove forest development plan in the study area has been proposed with the area and location of forest development for each period from 2011-2100:

- Period 2011-2030: Maintain strictly protected forest area (1,206 hectares) and increase forest planting and restoration in existing aquaculture areas (with a plan to plant 177 hectares and restore 659 hectares). ha mangrove).

- Period 2030 - 2050: continue to expand the area of ​​strictly protected forests, promote afforestation and forest restoration (by 2050, there will be 2,042 hectares of protected forest land and 1,581 hectares of newly planted and restored forest land ).

- Period 2050 - 2100: expand the area of ​​strictly protected forests, promote afforestation (by 2100, there will be 3,623 hectares of protected forest land and 1,109 hectares of restored forest land)