6. Restoration and management methods

Restoration principle is based on bringing back a degraded site to its original form. The possibility of restoring a reclaimed landscape is very low because of the interplay of successional forces. The conversion of a coastal environment to a terrestrial environment is absolute and cannot be reversed. Therefore, the best option is to remediate it so that it will carry out its ecological functions even if it results to another landform. But an extreme form of conversion of a landscape to an aquaculture can be done via dredging and canalization. This means areas that had been cleared and sand filled could be opened up again to be interconnected with the river, so that it will gradually become alive and revert to its original form [11]. This will however, take 10─20 years to stabilize. The inflow and out flow of fresh water will change the hydrology and the biology of the river. The area can be strictly protected against further anthropogenic activities to allow for evolutionary forces to change the restored environment. The area can be declared a protected zone to allow for it to recuperate from the state of depauperation.

The Impact of Landscape Reclamation on Mangrove Forest and Coastal Areas in the Niger Delta… DOI: http://dx.doi.org/10.5772/intechopen.82053

### 6.1 Case study: seedling recruitment experiment

Areas that have mangrove vegetation before can be restored through the exportation of mangrove soil and mangrove propagules and allowed for <sup>20</sup>─30 years to develop into a mature mangrove forest. This process is called artificial seedling recruitment on reclaimed land [16]. In a natural seedling recruitment, after a disturbance event the first set of species that settle and colonize an area are the pioneer species. They gradually occupy the area through seedling recruitment process. In a classical case of land recuperation after landscape reclamation at Eagle Island in the Niger Delta, recruitment occurred through natural process within a space of 1–3 years. In 2014, an area measuring 100 m 50 m was dredged and sand filled. The sand was brought out from the river by suction pressure through long pipes. The sand filled area became the dumping ground for sand, where trucks evacuated the sand to buyers. The side of the sand filled area was piled up to form balkanization against the inflow of river water. The sand mining activity was abandoned after 2 years of operation. In the course of this period a small outlet was created by the side of the sand filled area, which allowed the entry of river water into the sand filled area during high tide. Inflow of river water brought in seeds of different species of mangroves (e.g. red, white and black mangroves) and seeds of nipa palm and Heritiera littoralis. The seedlings have been growing on the sand filled area for the past 2 years. The plants growing on the sand fill area are between 0.5 m and 1.0 m tall. A field observation made indicates that seeds at the end of the sand filled area had better growth than seeds at the mouth of the entrance of the balkanized sand. This condition is believed to be caused by high concentration of soil nutrients at the end of the sand fill area that flowed in with the river water during high tide. Growth may also be facilitated by the absorption of soil nutrients embedded in the first layer of soil brought in by tides. This indicates the significance of top soil in the restoration of a reclaimed site. This is a natural ecological restoration. It is a regular progress or change by plant and animal due to natural or anthropogenic disturbances. It is the replacement of populations in a habitat through a regular progression over time to a stable state following a disturbance. In a preliminary study conducted in the sand dredged area, soil samples were collected for physico-chemical analysis at three sites (T1, T2 and T3) from the back of the sand filled area to the entrance of the sand fill area (Figure 8). Furthermore, census of species found in the area was made at the three study sites. The results of the physicochemical analysis and the species abundance test were derived as shown in Figure 9. The result indicates that Potassium and magnesium had the highest concentration. Although they were not significantly different from each site (F2, 12 = 0.19, P = 0.83). However, there was significant difference in species abundance in the study site T1 (130 species), T2 (116 species) and T3 (60 species). The most dominant species found was white mangroves (Laguncularia racemosa) (108) followed by red mangroves (Rhizophora racemosa) (104), black mangroves (Avicennia germinans) (77) and nipa palm (Nypa fruticans) (17). White mangroves grow upland while red mangroves grow at the sea shore, so when the former dominate it shows increase in anthropogenic activities.

The next kind of management is human management [19]. It involves human beings because they are the ones that cause problems for biodiversity. It is a system where plants and animals have advantage in reserved area. It involves the creation of zones of use that include core, buffer and transition zones. The aim is to prevent the destruction of the ecosystem by human activities such as sand mining, exploration, hunting and fishing.

3. Segregation: this is when units or communities cluster together based on homogeneity of ideals or goals. Homogeneous ideals such as customs, educational goals, and occupational goals all make up segregation. For instance, establishment of refinery in a locality leads to the reclamation of more coastal lands to harbor the cluster of people who come to seek for jobs.

Conversion of coastal environment to terrestrial area through deforestation and solidification to terrestrial

4.Invasion: this is as a result of the migration of people into coastal communities in search of new technologies that provide job opportunities. An example is the establishment of the liquefied natural gas (LNG) plant in Bonny Island in the Niger Delta region of Nigeria. This facility is situated at a coastal community that is land-locked. Thus in other to expand the land area to accommodate the industrial complex, surrounding creeks were mowed down; sand filled and

5. Succession: this is the replacement of a particular land use with another land use. The conversion of a coastal area to a terrestrial area via developmental projects is a human-mediated succession. The succession process in the Niger

The process in Figure 7 may be reversible or irreversible and if not reversible

Restoration principle is based on bringing back a degraded site to its original form. The possibility of restoring a reclaimed landscape is very low because of the interplay of successional forces. The conversion of a coastal environment to a terrestrial environment is absolute and cannot be reversed. Therefore, the best option is to remediate it so that it will carry out its ecological functions even if it results to another landform. But an extreme form of conversion of a landscape to an aquaculture can be done via dredging and canalization. This means areas that had been cleared and sand filled could be opened up again to be interconnected with the river, so that it will gradually become alive and revert to its original form [11]. This will however, take 10─20 years to stabilize. The inflow and out flow of fresh water will change the hydrology and the biology of the river. The area can be strictly protected against further anthropogenic activities to allow for evolutionary forces to change the restored environment. The area can be declared a protected zone to

can lead to the total loss of the mangrove forest and the coastal community.

solidifies to build offices and apartments for workers.

Delta occurs in three phases (Figure 7).

Figure 7.

64

environment in the Niger Delta, Nigeria.

Landscape Reclamation - Rising From What's Left

6. Restoration and management methods

allow for it to recuperate from the state of depauperation.

Figure 8. Experimental design of recruitment experiment in a sand dredged mangrove forest at Eagle Island in the Niger Delta, Nigeria. Sites T1,T2 and T3 are the end, middle and mouth of the sand fill area.

1. Replacement: instead of going back to the original, which is impossible, it

A proposed mangrove protect ted area design where no exploration, exploitation or reclamation activity will

The Impact of Landscape Reclamation on Mangrove Forest and Coastal Areas in the Niger Delta…

try to establish new habitat type because we cannot establish historic ecosystem. For instance, oil field that is established in mangrove swamp. Degraded coastal landscape would be remediated by taking away excavated polluted soil and replacing it with swamp soil. The water channel has to be set up to facilitate interconnectivity. The restoration of tidal force, edaphic factors and climatic effect will encourage natural recruitment of seedlings. The colonization of pioneer species will accelerate the establishment of other successional stages (e.g. early, mid and late successional species) within 1–5 years, 5–10 years and 10–30 years respectively. Another example is the replacement of invasive nipa palm forest with native mangrove forests.

2. Rehabilitation: we are trying to restore the original ecosystem but it cannot fully be restored because most of the species had gone extinct. An example is a construction project such as the installation of infrastructure on reclaimed coastal areas e.g. sea-side resort, roads, houses, light poles and shopping malls.

3.Restoration: it is the attempt to fully restore the original ecosystem. An example is a nipa palm invaded area. The palms are to be bulldozed with swamp buggies, mangrove top soil exported and seedlings planted to start a pioneer species in a mangrove protected area where no landscape reclamation activity

Landscape reclamation is used to remediate polluted and devastated area in many parts of the world such as abandoned coal mine, crude oil exploration site and abandoned aquaculture. But in the Niger Delta landscape reclamation is used to convert coastal areas to terrestrial areas. Two major activities that devastate coastal areas are sand mining and off-shore dredging. Sand mining is a thriving business in this area, which is done without proper environmental impact assessment or

occurs (Figure 10).

8. Conclusion

67

Figure 10.

occur in the Niger Delta, Nigeria.

DOI: http://dx.doi.org/10.5772/intechopen.82053

involves taking it to a different direction to create a replacement. We basically

Figure 9.

(A) Graph of species population along sampling points (T1,T2 and T3) indicates a decrease in number of species from point T1 (high nutrient content) to point T3 (low nutrient content); and (B) graph of concentration of physico-chemicals along within sites T1,T2 and T3.

### 7. Ecosystem management

Together the system of management is called ecosystem management, which is a way of managing reserve to benefit biodiversity and people. It is a strategy for protecting or restoring the function, structure and species composition of an ecosystem while providing for its sustainable socioeconomic use. The method is a natural recovery and a passive method of accomplishing restoration. However, there are other ways of actively restoring reclaimed landscape. They include:

The Impact of Landscape Reclamation on Mangrove Forest and Coastal Areas in the Niger Delta… DOI: http://dx.doi.org/10.5772/intechopen.82053

#### Figure 10.

A proposed mangrove protect ted area design where no exploration, exploitation or reclamation activity will occur in the Niger Delta, Nigeria.


#### 8. Conclusion

Landscape reclamation is used to remediate polluted and devastated area in many parts of the world such as abandoned coal mine, crude oil exploration site and abandoned aquaculture. But in the Niger Delta landscape reclamation is used to convert coastal areas to terrestrial areas. Two major activities that devastate coastal areas are sand mining and off-shore dredging. Sand mining is a thriving business in this area, which is done without proper environmental impact assessment or

7. Ecosystem management

concentration of physico-chemicals along within sites T1,T2 and T3.

Figure 9.

66

Figure 8.

Landscape Reclamation - Rising From What's Left

Together the system of management is called ecosystem management, which is a way of managing reserve to benefit biodiversity and people. It is a strategy for protecting or restoring the function, structure and species composition of an ecosystem while providing for its sustainable socioeconomic use. The method is a natural recovery and a passive method of accomplishing restoration. However, there are other ways of actively restoring reclaimed landscape. They include:

(A) Graph of species population along sampling points (T1,T2 and T3) indicates a decrease in number of species from point T1 (high nutrient content) to point T3 (low nutrient content); and (B) graph of

Experimental design of recruitment experiment in a sand dredged mangrove forest at Eagle Island in the Niger Delta, Nigeria. Sites T1,T2 and T3 are the end, middle and mouth of the sand fill area.

feasibility study. Continuous mining leads to the deformation of the coast lines and the destruction of aquatic organisms, which results in extinction of species. Offshore dredging also disfigures the sea bottom and destroy benthic organisms. Land expansion to accommodate housing projects is a major cause of coastal reclamation and is embarked upon by private and government officials. The suggested solution to revert an already devastated area is by applying natural and human mediated ecological principles to facilitate land and coastal recovery [20].

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