Evaluation of wetland ecological service function value in the Yellow River Delta

Wetland is a transitional zone between terrestrial ecosystem and aquatic ecosystem, and it is a multifunctional and unique ecosystem on the earth. It is not only rich in natural resources, but also has great ecological benefits. It plays an important role in flood storage and drought prevention, water conservation, soil and water conservation, climate regulation, environmental purification, land reclamation, sewage degradation, biodiversity protection and providing production and living resources for human beings. Therefore, the wetland is called the "kidney" of the earth, which has extremely high ecological service value.

Costanza, an American ecologist, divides the global ecosystem service functions into 17 items: gas regulation, disturbance regulation, water regulation, water supply, erosion control, sediment conservation, soil formation, nutrient cycle, waste treatment, pollination, biological control, shelter, food production, raw materials, genetic resources, leisure and culture. These functions of 17 have become people's ecological activities. For different ecosystem types, the service functions provided by ecosystems are quite different in content and quantity. The research shows that among all kinds of ecosystems, wetland ecosystem provides the highest service value. This chapter will evaluate the ecological service value of wetlands in the Yellow River Delta.

First, the Yellow River Delta wetland ecosystem service function

1. Overview of wetlands in the Yellow River Delta [82]

Located in the Yellow River Delta of Shandong Province, bordering Bohai Sea and Laizhou Bay in the east, it is a silt beach formed by the Yellow River with the largest sediment concentration in the world, which carries a lot of sediment to the estuary and is called the youngest land in China. The Yellow River Delta is rich in wetland resources, including offshore and coastal wetlands, river wetlands, swamps and swamp meadow wetlands, and artificial wetlands dominated by paddy fields, reeds and ponds. It is the fastest growing wetland ecosystem in the world and the most complete and extensive wetland ecosystem in the warm temperate zone of China. The wetland covers an area of about 4500km2, which is an internationally important wetland and needs to be registered by the contracting parties of Ramsar International Convention on Wetlands. As early as 1992, it has been established as a national nature reserve in the Yellow River Delta, the largest nature reserve in China and one of the most representative examples of estuarine wetland ecosystem in the world.

2. Wetland ecosystem services in the Yellow River Delta [83, 84, 160, 163]

The wetland ecosystem in the Yellow River Delta has the following service functions:

2. 1 Rich land resources and land reclamation functions

2. 1. 1 Land resource function: The Yellow River Delta is rich in land resources, with a per capita land area of 0.47hm2 in Dongying, the main city, and there is still 3.5× 105hm2 barren saline-alkali land to be developed and utilized. According to the suitability evaluation of land reserve resources, the land suitable for agriculture (cultivated land) is 8.65× 104hm2, the land suitable for forest (animal husbandry)1.313×105hm2, and the land suitable for aquatic products (salt industry)1. Large areas of wetlands remain in their original state. This unpolluted, flat and fertile land is called the most vital "virgin land" in the world.

2. 1.2 Land-making function: The Yellow River Delta is the fastest land-making estuary delta in the world at present, and about 20 ~ 23km2 of new land is formed every year [86].

2.2 marine resources function

The coastline of the delta is 350km long and the beach area is 1.2× 105hm2. Because the Yellow River and other rivers bring a lot of nutrients and organic matter into the sea, it is the most abundant water area of zooplankton in Bohai Sea, which provides good conditions for the reproduction, growth and reproduction of fish, shrimp, crab, shellfish and other fishery resources. Known as "the hometown of hundreds of fish" and "the hometown of oriental shrimp".

2.3 Habitat function

There are a total of 1524 species of wild animals in the area, including 4 18 species of marine aquatic animals, which belong to about 170 species under national key protection, including finless porpoises, bottlenose dolphins, spotted seals, minke whales and pseudo-killer whales. Freshwater fish 108 species, among which 3 species are protected by the state, namely Dashixian, Baixian and Songjiang Bass.

Delta, also known as "bird paradise", is an important "transit station" and wintering, habitat and breeding ground in the inland of Northeast Asia and bird migration around the western Pacific. At present, 270 species of birds have been found living here, accounting for 22.3% of the total number of birds in China, including 7 species of national first-class protected birds: red-crowned crane, white-headed crane, white crane, duck, merganser, white-tailed sea eagle and golden eagle. National key protected birds: swan, gray crane, mandarin duck, white-naped crane, etc. Up to 34 species. Black-billed gull, a rare bird in the world, is also widely distributed in nature reserves, where it nests, lays eggs and breeds. There are 40 species of birds listed in the Convention on International Trade in Endangered Species of Wild Fauna and Flora. It is a good season for bird watching from June 165438+ 10 to March of the following year. Red-crowned cranes, swans, black-billed gulls, striped geese and other migratory birds, travelers and resident birds can be seen everywhere in the mudflats and swamps around the Yellow River estuary. People compare the Yellow River Delta to "the international airport for birds".

2.4 Material production function

Can provide rich animal and plant products such as fish, shrimp, crab, shellfish, algae and other nutritious non-staple foods; There are special wild medicinal plants, mainly Suaeda salsa, Salicornia angustifolia, Hedysarum hedysari and so on. Many animals and plants are important raw materials for developing light industry, such as reeds, and are important raw materials for papermaking. The utilization of wetland animal and plant resources indirectly promotes the development of processing industry; Agriculture, fishery, animal husbandry and sideline production depend on the natural resources provided by wetlands to a great extent. It also includes various biological resources and marine aquatic resources. The unique ecological environment and natural conditions in the Yellow River Delta make wetland vegetation, water and soil organisms, birds and other biological resources extremely rich. There are 393 species of natural reed, Suaeda salsa, Tamarix chinensis, Limonium sinense and garlic in the Yellow River Delta National Nature Reserve, including natural grassland, natural willow forest, natural willow shrub forest, artificial locust forest and natural seedling forest. Wild soybean is an endangered plant under national second-class protection, which is widely distributed.

2.5 Sightseeing and aesthetic functions

Wetland has beautiful natural scenery and is a good place for tourism and entertainment. The Yellow River Estuary Wetland Eco-tourism Demonstration Zone has five functional areas, namely, swamp wetland ecological area, Huai Lin ecological reception area, reed wetland bird-watching area, beach wetland sightseeing area and new land sightseeing area, and has set up the "Ten Scenes" of the Yellow River Estuary, such as the window of wetland, the flying snow of reed flowers, the fragrance of Huai Lin, the green willow, the 10,000-mu natural grassland, the yellow dragon entering the sea, the maze of Lu Hai, the long beach watching the sea, the sunrise on the sea and the sunset on the long river, and so on.

Aesthetic value of wetlands: Suaeda salsa, Salicornia bigelovii Torr, Pinus elliottii and Artemisia hardcore in coastal wetlands have high ornamental value. The vast reeds are rolling in the blue waves, the water town is prosperous, the sky is blue, and many birds are fighting for feathers and are full of vitality. It is in harmony with wild animals such as red-crowned cranes and black-billed gulls, providing people with a good environment for tourism and recuperation.

2.6 Educational and scientific research value

The wetland ecosystem, diverse animal and plant communities and endangered species in the Yellow River Delta provide physical objects, materials and experimental bases for education and scientific research. Wetland retains the information of past and present biological and geographical evolution, which is of great value to the study of environmental evolution and paleogeography. Ecologists regard it as an important base for studying the formation, evolution and development of new land, biologists regard it as a gene bank for studying the laws of biological evolution and succession, ornithologists regard it as a special area for studying the survival, habitat and migration laws of birds in the inland of Northeast Asia and the western Pacific, and soil and water conservation experts regard it as a barometer reflecting the effectiveness of the Yellow River management. At the same time, it is also the national youth ecological education base.

2.7 Function of purifying the environment

Wetlands are conducive to purifying the environment and improving its quality. Large areas of reeds, meadows and swamps have the functions of purifying water quality and degrading pollutants in inland rivers, thus reducing the pollution in the Bohai Sea and improving the fishery production capacity and ecological function of the Bohai Sea. This is a natural sewage treatment plant. Reed has obvious effects on various pollutants in water, such as BOD5, SS, nutrients N, P, trace elements, refractory organic substances, pathogenic bacteria, etc. Its main mechanisms are physical precipitation, filtration, adsorption, chemical precipitation, decomposition, biological metabolism and so on. According to the experimental research of P.R. Adler, with the increase of wetland productivity, the ability to remove nutrients is also enhanced. The ideal lawn wetland can remove 92% phosphorus and more than 40% nitrogen. Recently, the "red tide" in offshore waters is caused by excessive nutrients in the water. Making full use of the purification function of wetlands is conducive to reducing the pollution of offshore water bodies and preventing the occurrence of seawater eutrophication.

2.8 flood storage and detention function

The function of wetland to store and retain flood is due to the small slope of the ground and the high groundwater level. Under the support of seawater, a large amount of river water is stranded in coastal wetlands, becoming a natural flood storage reservoir before land water enters the sea. If the wetland boundary is 5m above sea level, the area that can be used as a natural flood storage reservoir is about 1400km2 except the developed rice planting area. According to the average flood storage depth of 2m, the coastal wetland can store 2.8 billion m3 of flood, which plays an important role in regulating the water level and water balance of the downstream Yellow River Plain.

2.9 Adjustment function of atmospheric composition

Atmospheric components regulate the exchange of CO2 and O2 between ecosystem and atmosphere through photosynthesis and respiration, thus playing an important role in the dynamic balance of CO2 and O2 in the atmosphere. Wetlands are also sources of greenhouse gases, including CH4 and N2O.

2. 10 humidity adjustment function

Water regulation is one of the important functions of wetland, which has great infiltration capacity and water storage capacity. Due to the absorption and infiltration of precipitation by wetland plants, the time of precipitation entering the river lags behind, and the amount of precipitation entering the river decreases, thus reducing flood runoff and achieving the purpose of flood cutting.

Second, the evaluation method of wetland ecological service function value

1. Land reclamation value

The value of land reclamation is evaluated by market value method. Through market investigation, we know the local land use right transfer price, and take its average value of 465,438+0,000 yuan /hm2 for estimation. The annual natural reclamation area in the Yellow River Delta is 20 ~ 23km2, and this study uses 265,438+000 hm2 for estimation. The calculation formula of land reclamation value (V) is as follows:

V= local land use right transfer price × annual land reclamation area

V=V 1+V2= (land area+annual reclamation area) × local land use right transfer price = 2 100 hm2× 4 1 ten thousand yuan /hm2 = 86 1 ten thousand yuan.

2. Material production function

The functional value of material production is also evaluated by market value method. The calculation formula is as follows:

Economic evaluation of urban geological environment risk

In the formula (4- 1- 1), v is the value of material products, including both the value of aquatic products and the production value of raw materials; Si is the harvestable area of the first class substance, Yi is the intermediate class of the first class substance, and Pi is the market price of the first class substance.

The market price of products refers to the 2005 national price yearbook and the local actual price. When estimating the value of raw materials, the harvestable area is calculated as 50% of the total production area.

3. Adjustment value of atmospheric composition

The regulating function of atmospheric components can be divided into three parts: CO2 fixation by plants, O2 release and greenhouse gas emission. The adjustment function value of atmospheric composition is the fixation of CO2 by plants, which is the sum of this value and O2 emission minus greenhouse gas emission.

3. 1 plant carbon fixation value

Based on the production of organic matter in the Yellow River Estuary wetland ecosystem, according to the reaction equation of photosynthesis, it is estimated that 1g dry matter needs 1.62gCO2 and releases 1.2g CO2.

At present, the carbon tax method is usually used to evaluate the carbon fixation value of plants in the world, and the carbon tax rate is based on 150 USD /t(C) suggested by the Swedish government (i.e. 1024 RMB /t). This value is undoubtedly on the high side for China, so this paper uses China's reforestation cost method to calculate it. According to the annual net carbon growth of plants per unit area, afforestation cost and the total area of wetland plants, the carbon fixation value of wetland plants is calculated. The afforestation cost in China is 260.9 yuan /t [87].

3.2 O2 release and its value

The economic value is estimated by afforestation cost method and industrial oxygen shadow price method respectively, and the average value is calculated. According to the amount of O2 released per unit area, the afforestation cost of O2 and the price of industrial oxygen production, the economic value of oxygen can be calculated. The cost of CO2 afforestation is 352.93 yuan /t [87]. The price of industrial oxygen production is 0.4 yuan/kg [88].

3.3 Emissions of greenhouse gases

According to the product of greenhouse gas emission flux, natural wetland area and greenhouse gas emission value, the greenhouse gas emission value is obtained. In this case, the emission values of CH4 and N2O proposed by Pearce et al. in the Economic Analysis of Climate Change of OECD are used to evaluate the economic value of these two gases, and the emission values are 0.86 yuan /kg and 20 US dollars /kg respectively.

4. The regulating value of water resources or the functional value of flood storage and detention water.

The adjustment of total water quantity of wetland can be obtained according to the following formula

Economic evaluation of urban geological environment risk

In formula (4- 1-2), Si is the area of Class I land and Di is the water storage depth of Class I land. Calculation of water regulation value by shadow engineering method. By establishing the shadow project cost of the reservoir with storage capacity of 1t, the value of water saving is estimated. The total value of water regulation function is the product of total water regulation capacity and water storage capacity cost of intermediate water storage capacity. In this example, it is calculated that the input cost of each construction of 1m3 storage capacity is 0.67 yuan (this data is mostly used in domestic research at present).

Therefore, the functional value of flood storage and detention water is calculated by the market value method, and calculated according to the storable flood of 2.8 billion m3, it is

Functional value of flood storage and detention water = 2.8 billion m3×0.67 yuan/m3 = 65.438+876 billion yuan.

5. The value of pure water

The value of water purification in wetland is the sum of the value of removing nutrients and heavy metals in wetland. The production cost method is used to estimate the value of removing nutrients from sewage by estuarine wetland ecosystem. The value of removing heavy metals was estimated by expert evaluation method. Calculate the value of removing nutrients according to the following formula:

Et = EJ×Pj = max {Tj/ New Jersey %}×Pj

In the above formula, Et is the value of N and P for wetland purification, yuan/a; Ej is the amount of sewage purified by wetland, t/a; Pj is the value of unit discharge cost of sewage treatment plant, yuan/a; Tj is the amount of nitrogen and phosphorus in wetland purification; Nj% is the content of N and P in the sewage, and the maximum value of Tj/Nj% is the total amount of combined sewage purified by wetland, that is, Ej.

At present, the sewage treatment cost of secondary sewage treatment plants in China is 1.600 ~ 0.33 million yuan/10,000 tons (including ton water investment cost, ton water operation cost, ton water sludge treatment investment cost, ton water sludge treatment operation cost, etc.). ), the average monthly value is 2450 yuan/ten thousand t [89]. The nitrogen content of mixed sewage Nn% is 2.90% [90].

According to the expert evaluation method, the heavy metal removal value [9 1] is obtained by taking the environmental benefit value of wetland as 40% of the total environmental benefit value.

6. Habitat value

The habitat value was preliminarily evaluated by substitution method, and the average value of this value and the global wetland ecosystem habitat value was taken as the habitat value of estuarine wetland ecosystem. When calculating the habitat value by substitution method, the habitat value is preliminarily estimated according to the bird data in this area, in which the habitat protection investment = protection project investment+scientific research and cultural investment ×50%.

7. The value of cultural and scientific research

The average scientific research value of the ecosystem per unit area in China is 382 yuan /hm2, and the global average scientific research and cultural function of the wetland ecosystem by Costanza et al. is 86 1 USD /hm2, and the scientific research value as an estuary wetland is 3 129.9 yuan /hm2.

8. Aesthetic (tourism) value

Tourism value consists of three parts: tourism cost, tourism time and other expenses, calculated by the number of tourists received in 2005.

Travel expenses = transportation expenses+accommodation expenses+park tickets, scenic spots tickets and service fees.

Travel time cost value = total travel time of tourists × opportunity salary and other expenses of tourists per unit time = photography and shopping expenses

In the calculation of tourism time value, the salary of tourists is calculated according to 90 yuan /d, and the opportunity salary cost of tourists is generally 30% ~ 50% of the actual salary [92]. This study adopts a discount rate of 40%.

9. Total ecological value of estuarine wetland

The total value is equal to the sum of various values, namely

Total ecological value = land reclamation value+material production value+atmospheric composition adjustment value+moisture adjustment value+water purification value+habitat value+cultural research value+aesthetic (tourism) value+flood storage and detention function.

Three. Evaluation results and discussion

In this paper, the service function of wetland ecosystem in the Yellow River Delta is divided into 8 types, and the service value of wetland ecosystem is 9.45 billion yuan /a ... See Table 4- 1- 1 for the evaluation results of various services. Among them, the value of wetland ecological service is higher in land reclamation value, material production value and cultural research value, followed by aesthetic value, water purification value, habitat value, water regulation value and gas regulation value. The wetland service value per unit area in the Yellow River Delta is 1.79 million yuan/hm2 a, which is far greater than the national ecosystem service value per unit area (0.54 million yuan/hm2 a). Compared with Wu Lingling et al. [65438], this shows that the wetland ecosystem service value is very high, which is consistent with the research results of Costanza.

Table 4- 1- 1 Evaluation Results of Ecosystem Service Value in Yellow River Delta

(1) The land reclamation value of wetlands in the Yellow River Delta is relatively high, accounting for 10438+0% of the total value. Because the river water in the middle and upper reaches of the Yellow River (especially the annual water and sediment regulation project after the operation of Xiaolangdi Reservoir) transports a large amount of river sand to the estuary of the Yellow River and accumulates land, which creates rich tidal flats and land resources, which determines that wetlands have high land-forming value.

(2) There are usually two methods to evaluate the value of habitats. One is substitution method, that is, the value of habitat is replaced by direct investment in protected areas. The other is CVM conditional value method, which is realized by investigating WTP(Willingtopay) or WTA(willing to pay). CVM is greatly influenced by the evaluator's subjective factors. In developed countries with low Engel coefficient, people pay more attention to the environment and the value of habitat. Replacing the habitat value with protected area investment by substitution method is based on China's emphasis on protected areas and its ability to pay, and the result is lower than the world's evaluation of habitat value. The author thinks that it must be based on the appropriate national conditions, but also take into account the evaluation of this function abroad.

The evaluation results show that the habitat value accounts for 20.7 1% of the total value, which is extremely high. As an evaluation area, both biodiversity and exotic animals and plants are rare in the world, which is not high by the standards of developed countries, but it may be a bit high for China.

(3) In this study, the value of cultural research is very high, accounting for 2 1.438+0%. In fact, at present, the cultural and scientific research value of the Yellow River Delta wetland is far from being developed and utilized, and the actual utilization value is far below this value, which also shows that the cultural and scientific research value of the wetland has great potential for development and utilization.

(4) Among the above eight ecological function values, the function value of flood storage and detention water is the highest, accounting for 23.33% of the total value. Perhaps, for the evaluation area, due to the salinization of soil in most areas, the cultivated water quality is relatively poor, and the evaluation result may be high. But because there is no more suitable method than engineering cost method, we can only accept this result.

(5) When estimating the value of purified water, it is mainly to estimate the realized purification function of wetland, and the estimation of the potential purification function value of wetland needs further study.