عنوان مقاله [English]
Ecosystem services are the benefits people get from ecosystems and human always needs ecosystem services and products for survival. These services are divided into four categories of productive, regulatory, cultural and life support services; the first three categories are directly affecting people, and the fourth one is critical for the continuation of other services provided by ecosystems. Each of these four categories comprises a wide range of services. Since ecosystem services are not either fully tradable in commercial markets or quantifiable like economic services, they are often being ignored in policy making and spatial planning. Assessing the impacts of landuse/landcover changes on the ecosystem service values is required for the special economic zones that are experiencing rapid changes in land use/land cover. Pars Special Economic Energy Zone (PSEEZ) located in southern Iran is considered as an example of these areas which has become a national and transnational zone within a short period of time due to the activities related to the extraction, exploitation, refining and exporting of gas resources. Extensive industrial investment has been made in less than 10 years in this zone. This area was established in 1998 to extract oil and gas resources from the South Pars Oil Field with economic activities carried out in the city of Assaluyeh, Bushehr province. The Nayband national marine park is located in the PSEEZ along with a part of Nayband's headland with an area of 19,500 hectares. It was designated as Nayband Protected Area in Iran. This area stretched along the coast of Persian Gulf in an approximate area of 49,815 hectares, were registered as the first Iranian marine national park in 2003. The presence of coral reefs, mangrove forests, rocky beaches, and real estuaries make this area one of the most diverse and beautiful coastal ecosystems in the world. There are also various aquatic species, marine mammals such as dolphins and whales, endangered reptiles, such as the green and eagle tip turtle and various kinds of aquatic birds in the area. The construction of PSEEZ has led to development of petrochemical refineries, which in turn resulted in an increase in population (from 2000 to 60,000) and the expansion of human settlements. On the other hand, the development has led to the expansion of land, sea, and air transport infrastructure. Due to the rapid changes in this region, it is required to assess the impacts of landuse/landcover changes on the ecosystem service values. In this regard, remote sensing as the most important way of obtaining the spatial data, allows the quantification and mapping of these services. This technology brings practical benefits to biodiversity conservation and promotes the sustainable utilization of natural resources within the arena of ecosystem services.
This research emphasizes on landuse/landcover changes as the basis of the evaluation of ecosystem services. In assessing the status of changes in the PSEEZ, a surface area of 300,000 hectares (3000 square kilometres) were reviewed over a period of 32 years. Those images of 1986 and 1998 were considered to show the trend of regional changes before the establishment of the PSEEZ, and the image of 2018 was used to show the current changes. In selecting Landsat images, we considered climate conditions as well as the characteristics of the Persian Gulf tide and its effects on mangrove forests. The weather condition of the region is suitable for farming during the winter season. According to the data captured by remote sensing images, crop fields in the months of January, February and March had better resolution than other months of the year. To classify the images for detecting the changes, Random Forest technique was used for the higher classification accuracy and processing speed compared to the other two methods. In assessing the economic value of the ecosystem services in the PSEEZ, landuse/landcover changes and global estimations of ecosystem services are integrated.
Results and discussion
The results indicate that agricultural lands and palm groves had a significant increase of 308.79 and 852.48 hectares before the establishment of the PSEEZ and the mangroves forests decreased by 67.68 hectares. With the establishment of the PSEEZ, human built-ups and mangrove forests were increased by 2756.61 and 113.4 hectares, while Barren lands, agricultural lands and palm groves decreased by 4651.92, 397.53 and 579.33 hectares.
The drying of wetlands for the construction of roads and airports has greatly reduced the size of the wetland area with an estimated loss 100 million dollars for economic value of the ecosystem services. The results also indicate that the economic value of the ecosystem services of the PSEEZ for the years 1986, 1998 and 2018 is equal to 570.02, 393.92 and 463.52 million dollars, respectively. The service function and its changes indicate that erosion control, recreation, nutrient cycling, waste treatment and food production are of the highest value in the study area. In contrast, pollination, gas regulation, soil formation, water supply and biological control have indicated the lowest value. It was revealed that during these years, water regulation, habitat/refugia, disturbance regulation, erosion control and recreation had the highest changes about 22.772, 12.445, 11.89, 10.791 and 9.192 million dollars in the study area.
Based on the findings of this research, we conclude that the status of the Nayband wetland is in a warning state, and human built-ups in its remaining space should be avoided. More attention must be paid to potential of the recreation ecosystem service of this region for its preservation. Since it is not possible to classify coral reefs in the region (Haleh and Asaloyeh) with these images, the studies are recommended to review their ecosystem service value. It is necessary to investigate the condition of the estuaries (Bidkhun or Asaloyeh, Basatin and Haleh) and mangroves in these estuaries to make policies for their preservation and development.