Emergy Evaluation of Mai Po Mangrove Marshes

______www.paper.edu.cn

Ecological Engineering 16 (2000) 271–280 www.elsevier.com/locate/ecoleng

Emergy evaluation of Mai Po mangrove marshes

P. Qin a, Y.S. Wong b,*, N.F.Y. Tam b

a Department of Biology, Nanjing Uni6ersity, Nanjing 210093, PR China b Department of Biology and Chemistry, City Uni6ersity of Hong Kong, Tat Chee A6enue, Kowloon, Hong Kong

Received 5 January 1999; received in revised form 25 February 2000; accepted 3 March 2000

Abstract

This study is an emergy evaluation of Mai Po mangrove marshes. The important emergy indices of the system are as follows, the total output emergy of the marshes is 26.39×1017 sej/year; its macroeconomic value is 25.87×105 per year (in 1988 Hong Kong); its emergy density is 6.94×1011 sej/m2 per year; and its investment ratio (IR), environmental loading ratio (ELR), yield ratio (YR) are 0.48, 1.03, and 3.10, respectively. The emergy of education function in Mai Po was tentative calculated as 125.65×1017 sej/year, its macroeconomic value is 123.19×105 $ per year (in 1988 Hong Kong), in which the knowledge distribution is outstanding, about 99.26×1017 sej/year, the macroeconomic value is 97.31×105 $/year (in 1988 Hong Kong), occupied 92% of all investments of whole education system. These data show that used emergy of per area in Mai Po is high and the management and education function of the natural reserve is good, but environmental loading is high. © 2000 Elsevier Science B.V. All rights reserved.

Keywords: Emergy evaluation; Mai Po; Natural reserve; Mangrove marshes

1. Introduction (called gei wai by the locals) and a quiet and safe mudﬂat attracts a great deal of bird, Over 60 000 The Mai Po marshes are the largest remaining winter birds used the area in January 1996 (The and most important wetland in Hong Kong. Its Nature Conservation Bureau and Wetlands Advi- total area is 380 ha, including 250 ha ponds and sory Service, 1997). This is a wonderful landscape 130 ha mangrove marshes. In September 1995, the in Mai Po. The marshes also draw much interest Mai Po marshes and the inner Deep Bay were from a lot of people including scientists which listed under the convention on Wetlands of Inter- make multi-discipline researches, for example, national Importance especially as Waterfowl productivity and nutrients of mangrove marshes Habitat (the Ramsar Convention). A wide variety (Lee, 1989a,b, 1990a,b; Tam et al., 1990, 1998; of habitat types with higher productivity of man- Anderson, 1992), ecology of gei wai and ﬁsh grove marshes, distinguished tidal shrimp ponds ponds (Poovachiranon, 1986; Lee, 1989b; Aspin- wall et al., 1996; Young and Chan, 1997), the * Corresponding author. Tel.: +852-2788-9377; fax: +852- 2788-9377. birds and biodiversity in Mai Po marshes E-mail address: [email protected] (Y.S. Wong). (Melville and Morton, 1983; Lee, 1986; Chalmers,

0925-8574/00/$ - see front matter © 2000 Elsevier Science B.V. All rights reserved. PII: S0925-8574(00)00104-X 272 ______中国科技论文在线 P. Qin et al. / Ecological Engineering 16 (2000) 271–280 www.paper.edu.cn

1989, 1990, 1992), etc. The rough values of gei wai al., 1997) emergy theory research (Odum, 1983, and fish pond, and the education significance of 1996; Jorgenson et al., 1995; Patten, 1995; Tiezzi Mai Po have been evaluated and appraised (Axell, et al., 1996); etc. But there was less emergy evalu- 1983; Nelson, 1993), but nobody is concerned to ation on mangrove marshes (Gunderson, 1989), estimate the ecological–economic benefits (real of course, not Mai Po mangrove marshes. wealth) in Mai Po with emergy analysis. In this study, emergy analysis is used to evalu- Using the monetary cost of reinforcing nature ate the integrative ecological–economic benefit of as a measure of its value underestimate the wealth Mai Po marshes and the real wealth of its ecosys- required for replacement (Jansson, 1984; Odum, tem, education function. The sustainability policy 1996), because the major free environmental con- and manner of the marshes will be briefly tributions are not included in the cost. suggested. A science-based evaluation system is now avail- able to represent both the environmental values and the economic values with a common measure. 2. Methods This is emergy evaluation, which measures the energy of one type directly and indirectly used in 2.1. Study area the production to generate a product, whose units are solar emjoules (sej) Odum, 1988. This evalua- The Mai Po marshes lies in 22°30%N, 114°00%E, tion provides a quantitative way to find what on the edge of Deep Bay at northwestern part of policies and patterns for humanity and nature are Hong Kong, are located to the east of the Zhuji- sustainable, with less trial and error, because they ang River estuary (see Fig. 1). Its total area is 380 tend to anticipate self-organization for maximum ha, including 250 ha ponds and 130 ha man- benefit and prosperity. groves. In fact, Deep Bay is shallow, its average In recent years, research using emergy evalua- depth is only 3 m and the deepest depth is 6 m. Its tion has been active, including national and re- largest tide difference is only 2.8 m, so there is a gional emergy analysis of environment, economy wide mudflat when the tide receded. and public policy (Huang and Odum, 1991; Lan The mangrove at Mai Po is the largest stand of and Odum, 1994; Ulgiati et al., 1994; Brown and mangrove in the territory and covers an area of McClanahan, 1996); emergy evaluation of ecosys- 130 ha. The mangrove is located in transition of tem and economic system (Odum, 1984; Gunder- the inter-tidal mudflat and the gei wais. A total of son, 1989; Bastianoni and Marchettini, 1996; Eum six species of mangrove are found and these are et al., 1996; Sohn et al., 1996; Tong, 1996; Day et Kandelia candel, Aegiceras corniculatum, A6icennia

Fig. 1. The position of Mai Po Natural Reserve in Hong Kong. A, Mai Po Natural Reserve; B, the district of Hong Kong; C, the continent of China. ______中国科技论文在线 P. Qin et al. / Ecological Engineering 16 (2000) 271–280 www.paper.edu.cn 273 marina, Acanthus ilicifolius, Excoecaria agallocha, The emergy investment ratio (IR) is the ratio of and Bruguiera gymnorrhiza. Among them the spe- feedback inputs (F) to all emergy derived from cies of K. candel is the largest population in Mai local sources (the sum of R and N), where R is Po. The productivity of mangrove ecosystem is local renewable emergy and N is the emergy from relatively high and supports a high diversity of local nonrenewable sources. organisms. The most prominent one will be the F colorful fiddler crab, Uca sp. and their burrows IR= can be easily seen under the mangrove. Mangrove (R+N) barnacle and snail are also abundant around the The name is derived from the fact that it mangrove stem. is a ratio of emergy ‘invested’ from the econ- A wide variety of habitat types can be found omy to resident emergy. The larger the in- within the reserve that includes natural and man- vestment ratio the greater the intensity of develop- made habitats. In the center of the reserve there ment. are the man-made tidal shrimp ponds, called ‘gei The environmental loading ratio (ELR) is the wai’. They are large rectangular ponds (each area ratio of nonrenewable emergy (N+F) to renew- is about 10 ha) surrounded by dykes with one able emergy (R) as follows: sluice gate for each pond on the seaward side to control the water inflow and outflow between the (N+F) ELR= bay and the ponds at different tides. The central R part of the gei wai is covered by vegetation domi- nated by the mangrove species and the reeds Low ELR reflects relatively small environmen- (Phragmites sp.). Fallen leaves as an organic input tal loading, while high ELR suggests greater and shrimp larvae from the Deep Bay make the loading. gei wai a self-sufficient system for shrimp produc- The emergy YR is emergy of yield divided by tion. Within the gei wai, the rapid accretion rate the emergy of all the feedback from the economy means that the channel around the edge of each (e.g. tourism income, several funds and services in pond has to be dredged every 10–12 years, so that this study), i.e. YR=(R+N+F)/F (in this sys- a water column of approximately 1–1.5 m is tem the output emergy is calculated by summing maintained for prawn production. So Mai Po is a emergy inputs). paradise of birds as feeding, roosting, breeding The emergy YR of each system is a measure of and nesting grounds as well as refueling station its net contribution to the economy. for migratory. 2.4. Determining the real wealth of education 2.2. General methodology for emergy analysis function in Mai Po

The general methodology for emergy analysis is The real wealth of education function in Mai a ‘top-down’ systems approach (Odum, 1988, Po is important to evaluate the synthetic effect of 1996). the system. The emergy evaluation includes not only financial and material investments, environ- 2.3. Determining the important emergy indices mental resources, but also intellectual. In this study, the knowledge contribution is calculated In this study, a series of emergy indices will be tentatively as the intellectual investment. The ma- determined. Among them the emergy investment jor knowledge contribution in Mai Po is derived ratio, environmental loading ratio and the net from its staffs, the emergy of knowledge contribu- emergy yield ratio (YR) are rather important, tion per individual is as follows, the total annual because they reflect directly the relationship be- used emergy of Hong Kong divided by the popu- tween economic and environmental subsystems, lation in different hierarchical level of education and ecological–economic benefit. (Odum, 1996). 274 ______中国科技论文在线 P. Qin et al. / Ecological Engineering 16 (2000) 271–280 www.paper.edu.cn

GPP is only 0.9%; Lee, 1990b), and is not listed in the GPP items. K. candel materials are used to measure the mangrove productivity because it is the largest population in Mai Po. The emergy transformity of gross production estuary is used to the three primary production items in this study, i.e. 4700 sej/J (Odum, 1996). The investments include three items that are facilities and service supported by World Wildlife Fund (WWF), Hong Kong (HK) and several other funds, about US$ 4.1×105 per year; government budget, about US$ 1.8×105 per year; tourism income supported by the tickets of the Fig. 2. Emergy diagram for input and output of Mai Po. A, natural reserve, about US$ 2.44×105 per year. So sun; B, wind; C, rain; D, tide and wave; E, mangroves; F, the total investments are US$ 8.34×105 per year. reeds; G, macroaiage; H, mud and sediments; I, ponds water; J, facilities and service; K, government budget; L, tourism The intellectual investment of the staffs in Mai Po income; M, aquaculture production; N, Nekton flow; O, wais discussed in the education system of Mai Po. terfowl; P, education function; Q, market. Aquaculture production which is shrimps and fishes harvested from and other fish ponds is an 3. Results and discussion important outflow of the system and one of the major economic income of Mai Po reserve and 3.1. Emergy e6aluation for input and output of about 400 kg/ha per year (Melville and Morton, Mai Po 1983). The gei wai is self-sufficient system in which larvae of shrimp and fish come from the The aggregated system diagram in Fig. 2 illus- Deep Bay and their food from the litters of man- trates the emergy inputs of renewable and nonre- grove and reed, but its aquaculture harvest is not newable sources, including sun, rain, tide, wave, high and the contradictory between ecological and mud sediments, ponds water, etc. The renewable economic benefits emerged. According to the sources are identified as rain (chemical) and wave, principle of priority in environment protection the and the nonrenewable is as mud sediments. Wind, commercial aquaculture production in Mai Po tide and sunlight are not added into the total Natural Reserve could not be much developed. So renewable flow of emergy as same as ponds water WWF Hong Kong has purchased areas to restore is not added into the total nonrenewable flow the gei wais and maintain the ecological feature in (Table 1), since they are a part of the same the system. Now the total area of gei wai in Mai coupled solar and earth based flows, it would be Po is about 150 ha. double counting to add the emergy of each. It is The Mai Po Natural Reserve is best known for emphasized that both annual quantities of rainfall bird watching in the cooler season. Over 70% of and wave in Mai Po are lower, its annual rainfall the birds recorded in the territory can be found at only 1400 mm, much less than the average level of Mai Po. So evaluating the emergy transformity of Deep Bay (Chiu and So, 1986), and the extreme waterfowls in Mai Po is very important. The wave heights in whole Deep Bay is limited (Li and wetlands are particularly important as feeding, Lee, 1996). These are the geographical reasons, roosting, breeding and nesting grounds as well as e.g. the rain shadow role of Mountain Tai Mo refueling station for migratory birds. Among Shan and the shallow water depth of Deep Bay. these migrants are some globally threatened spe- Besides, the gross primary production (GPP) in cies such as black-faced Spoonbill (Plalatea mi- Mai Po marshes includes mangrove, reed produc- nor), Saunders’ Gull (Larus saundersi ), Asiatic tion, macroalgae and phytoplankton, but the Dowitcher (Limnodromus semipalmatus) and spot- quantity of last one is too little (the proportion in ted Greenshank (Tringa guttifer). The more com- ______中国科技论文在线 P. Qin et al. / Ecological Engineering 16 (2000) 271–280 www.paper.edu.cn 275

Table 1 Emergy evaluation of principle ﬂows for Mai Po

Item Raw data (J orTransformity (sej/U) Solar emergy (×1017 sej) Macroeconomic value×105 1988 US$) US$

Renewable sources (J) Rain, chemical a 2.63E+1315444 4.06 3.98 Wavesb 3.02E+13 25889 7.82 7.67 Earth cyclec 3.80E+12 29000 1.10 1.08 Total 12.98 12.73 Nonrenewable sources (J) Mud and1.40E+14 3509 4.91 4.81 sedimentsd GPP (J) Mangrove4.79E+13 4700 2.25 2.21 productione Reed productionf 1.54E+134700 0.72 0.71 Macroalgaeg 0.06E+13 4700 0.03 0.03 Total 3.00 2.95 In6estments ($) Facilities and4.10E+51.02E+12 4.18 4.10 serviceh Government 1.80E+5 1.02E+5 1.84 1.80 budgeti Tourism incomej 2.44E+5 1.02E+12 2.48 2.44 Total 8.50 8.34 Fishes, shrimps and crabs (J) Aquaculture 1.07E+11 1.3E+7 13.91 13.64 productionk Nekton ﬂowl 3.02E+103.1E+7 9.36 9.18 Total 23.27 22.82

a Rain, chemical energy, area×rainfall×density×Gibbs number (Odum, 1996)=3.8×106 m2×1.40 m/year×1×103 kg/m3× 4.94×103 J/kg=2.63E+13 J/year. b Waves energy, 1/8×shore length×density×gravity×height2×velocity×3.154×107 (Odum, 1996)=0.125×3.5×103 m×1.03× 103 kg/m3×9.8 m/s2×(0.2 m)2×(9.8 m/s2×3m)1/2×3.154×107 s/year=3.02E+13 J/year. c Earth cycle energy, area×heat ﬂow per area (Odum, 1996)=3.8×106 m2×1×106 J/m2 per year=3.8E+12 J/year. d Mud and sediments energy, area×peaty sediments energy (Odum, 1996)=3.8×106 m2×3.69×107 J/m2 per year=1.4E+14 J/year. e Mangrove production energy, area×GPP of mangrove×standard energy value of C (Lee, 1990b; Odum, 1996)=1.3×106 m2×1.1×103 gC/m2×8 kcal/g×4186 J/kcal=4.79 E+13 J/year. f Reed production energy, area×GPP of reed×standard energy value of C (Lee, 1990b; Odum, 1996)=0.46×106 m2×1.0×103 gC/m2×8 kcal/g×4186 J/kcal=1.54 E+13 J/year. g Macroalgae energy, area×cover rate×GPP of algae×standard energy value of C (Lee, 1990b; Odum, 1996)=2.5×106 m2×0.15×0.5×102 gC/m2×8 kcal/g×4186 J/kcal=0.06 E+13 J/year. h Management and services, the grants in facilities and management=3.2×106 HK$ per year/7.75 (HK$/US$)=4.1 E+5 US$ per year. i Government budget, the grants in investments for production and leases=1.38×106 HK$ per year/7.75 (HK$/US$)=1.8 E+5 US$ per year. j Tourism income, the tourists number×ticket’s fee=26 962 per year×70 HK$/7.75 (HK$/US$)=2.44 E+5 US$ per year. k Aquaculture production, area×aqua-production/m2 per year×dry rate×standard energy value (Homer, 1977; Melville and Morton, 1983)=0.8×106 m2×40g/m2 per year×0.2×4 kcal/g×4186 J/kcal=1.07 E+11 J/year. l Nekton ﬂow in tidal channels, area×Nekton’s weight per m2/year×dry rate×standard energy value (Homer, 1977)=1.7×106 m2×5.3 g/m2 per year×0.2×4 kcal/g×4186 J/kcal=3.02 E+10 J/year. 276 ______中国科技论文在线 P. Qin et al. / Ecological Engineering 16 (2000) 271–280 www.paper.edu.cn

Table 2 Calculation for emergy transformity of waterfowl in Mai Po

ItemRaw data (J or Solar emergySupport rate (%) Support’s emergy US$) (×1017 sej/year) (×1017 sej/year)

Nektons3.02E+10 9.36 100 9.36 Aquaculture production1.07E+11 13.91 100 13.91 Investments 8.34E+5($)8.50 50 4.25 Total 27.52 Waterfowla 2.67E+10 27.52 The transformity of 1.03×108 sej/J waterfowlb

a Waterfowls (J), numbers×average weight×dry rate/replace time×standard energy value=20 000×0.8×103 g×0.2/2 year×4 kcal/g×4186 J/kcal=2.67 E+10 J/year. b The transformity of waterfowl=27.52×1017/2.67×1010 =1.03×108 sej/J. mon bird species are the herons and egrets, includ- emergy inputs to the same system. Using inputs for ing the Chinese Pond Heron (Ardeola bacchus), outputs assumes a priority that there are not little Egret (Egretta garzetta) and great Egret unnecessary wastes and losses. The total emergy of (Casmerodius albus). They can be found usually environmental work is 17.89×1017 sej/year. So the flying above the marshes or standing patiently in IR, ELR and the emergy YR of Mai Po are 0.48, shallow water, waiting to catch the prey. During 1.03, and 3.10, respectively. low tide, thousands of Sandpipers, Plovers, Curlew Comparing with Everglades National Park and Whimbrel can be seen feeding on the mudflats. (Gunderson, 1989) whose IR, ELR and YR are By observation records Mai Po can support 20 000 0.82, 0.82, and 2.22, respectively (Fig. 4), it shows waterfowls on ordinary occasions (the Nature Con- that the intensity of development (IR) in Mai Po servation Bureau, HK, 1997), the total energy of Natural Reserve is less, but its ELR is relatively waterfowls could be obtained. Then considering the higher, and its net contribution to the economy total emergy of supporting the birds (assuming the (YR) is more. Their emergy density (ED) are 11 investments support rate is 50%) the emergy trans- 3.82×10 (in Everglades National Park (ENP), 11 2 formity of waterfowl in Mai Po was calculated as USA), and 6.94×10 sej/m per year (in Mai Po Table 2. There is a slight difference between the Natural Reserve (MPNS)) which reflects the emergy of waterfowls and output flow in the system emergy of local resource per unit area in Mai Po (Fig. 3), that is due to the evaluation of support’s is higher and the investment level per unit area of emergy of investments on the waterfowls and the the natural reserves is corresponding. statistics of waterfowl number. Anyway, the ecological buffer of ENP is much larger, because its area is three times of whole Hong 3.2. En6ironmental and economic contribution of Kong. It is not easy to keep the low level of Mai Po development intensity and environmental loading, and the high level of biodiversity and net contri- The emergy indices of Mai Po marshes are listed in Table 3. Among them renewable emergy flow (R), nonrenewable emergy flow (N) and flow of investment emergy (F) are 12.98×1017, 4.91× 1017, and 8.50×1017 sej/year, respectively. The total emergy inflows of this system are 26.39×1017 sej/year, and it is also the system’s output (see Fig. 3). This is the principle of system’s emergy evaluation and output emergy is calculated by summing Fig. 3. Summary of emergy flows for Mai Po (×1017 sej/year). ______中国科技论文在线 P. Qin et al. / Ecological Engineering 16 (2000) 271–280 www.paper.edu.cn 277

Table 3 Emergy indices for Mai Po

NumberDescription Expression Quantity

1 Renewable emergy flow R 12.981017 sej/year 2 Nonrenewable emergy flow N 4.911017 sej/year 3 Flow of investment emergy F 8.501017 sej/year 4 Total emergy inflowsI=R+N+F 26.391017 sej/year 5 Total emergy of environmental work E=R+N 17.891017 sej/year 6 The investment ratioIR=F/E 0.48 7The environmental loading ratio ELR=(F+N)/R 1.03 8 The emergy yield ratioYR=(R+N+F)/F 3.10 9Emergy density Used emergy/area 6.941011 sej/m2 10HK emergy/$ Used emergy/GDP (1988) 1.021012 sej per US$ bution to economy in a long term in Mai Po that obvious that the output emergy of the education is in Hong Kong with high economic level. So system is much more than that of the natural enacting a series of the local laws and policies to system in Mai Po, because the knowledge contri- limit the land development of Mai Po and around bution per person per year is relative to his or her it, and to reduce its environmental loading is very concentration of knowledge in past years. People important and urgent for Mai Po. including students and tourists could much benefit from the education function of Mai Po. 3.3. E6aluating emergy for education function in It is interesting that tourists as same as the Mai Po birds watched in annual census (usually in Janu- ary) were more and more from 1988 to 1996. It The great educational value of Mai Po is fa- shows that Mai Po’s habitat benefits waterfowls mous and this was one of the prime objectives and the natural reserve also benefits tourists and with which WWF HK took over its management students as its special landscape and scientific (indicated by the title — the Mai Po marshes value. As the emergy density in Mai Po is higher Wildlife Education Center and Natural Reserve). (6.94×1011 sej/m2) and its investment ratio is Its education function is integrative, not only in lower (only 0.48), so its potential for drawing teaching for students and children, in training for more birds would be much. the management members of other reserves, but also in scientific tourism and bird watching. So all staff of the Reserve have served to inte- grate education, and the emergy of their knowledge contribution is a major fraction of education function in Mai Po. The emergy flows of education function and its accounting are illustrated in Fig. 5 and in Table 4, respectively. There are only 17 staff (three persons have Ph.D. or M.S. degree, three have B.S. degree and others are studying in their jobs) in the Reserve with 380 ha, but their knowledge contribution is rather high, about 99.26×1017 sej/year and occupies 92% of all in- 17 Fig. 4. Comparison of emergy indices between MPNS and vestments (107.76×10 sej/year) and 80% of to- ENP USA. IR, investment ratio; ELR, environmental loading 17 tal input flows (or output flow) (125.65×10 ratio; YR, emergy yield ratio; and ED, emergy density (E11 sej/year) in the whole education system. It is sej/m2 per year). 278 ______中国科技论文在线 P. Qin et al. / Ecological Engineering 16 (2000) 271–280 www.paper.edu.cn

and 3.10, respectively. Second, the emergy of education function in Mai Po is 125.65×1017 sej/ year, its macroeconomic value is 123.19×105 $ per year (in 1988 Hong Kong), in which the knowledge distribution is outstanding, about 99.26×1017 sej/year, the macroeconomic value is 97.31×105 $ per year (in 1988 Hong Kong), occupied 92% of all investments of whole education system. Third, these data show that used emergy of per area in Mai Po is higher, and the management and education function of the natural reserve is good, but environmental loading is Fig. 5. Emergy flows for education function in Mai Po (E17 sej/year). A, renewable sources; B, environmental work; C, high. Mai Po Natural Reserve can rationally ar- nonrenewable storage; D, facilities and services; E, knowledge range the tourism, scientific investigation and contribution; F, budget and tourism. study, and training with its high emergy resources to obtain much more education benefits. Mai Po Natural Reserve can rationally arrange Mai Po’s area is only one of the 40 marshes of the tourism, scientific investigation and study, and Hong Kong but its importance far transcends training with its high emergy resources to obtain their size. At one time such marsh extended along much more education benefits. much of the shore of Hong Kong. Today the Mai Po is the largest surviving remnant. But now trading, industrial, and other development pur- poses in Hong Kong need new land development, 4. Summary especially in the low land. Mai Po has faced much stress. A large new residential area has been con- This study on emergy evaluation of Mai Po structed adjacent to the marshes. An array of mangrove marshes has obtained a series of con- roads, sewer lines and other infrastructure has clusions. First, the total output emergy of the been built to serve these new urban areas. So marshes is 25.29×1017 sej/year, its macroeco- enacting a series of the local laws and policies to nomic value is 24.8×105 $ per year (in 1988 limit the development of Mai Po and around it, Hong Kong) and its emergy density is 6.94×1011 and to reduce its environmental loading is very sej/m2 per year, its IR, ELR, YR are 0.48, 1.03, important and urgent for Mai Po.

Table 4 Emergy evaluating of education function service in Mai Po

Note Item Emergy ﬂows (×1017 sej/year) E5$ (1988, ×105)

1 Environmental work 17.89 17.54 2 Facilities and services 4.18 4.10 3Budget and tourism 4.32 4.24 4 Knowledge contributiona 99.26 97.31 5 Total (education function) 125.65 123.19

a In Hong Kong the population of Master and Ph.D. is about 20 823 people, the population of bachelor and corresponding degree is about 354 566 people and the population of studying on the job is about 428 316 people (resource from Lee, Yuan Hao, Education and Manpower Bureau, Government Secretariat, Hong Kong). The total used emergy of Hong Kong (1988) was 556.94×1020 sej/year (Lan and Odum, 1994). So average emergy per individual of the three populations are calculated, respectively, as follows: 556.94×1020 sej/year per 20 823=26.75×1017 sej per individual per year (Master and Ph.D.); 556.94×1020 sej/year per 354 556= 1.57×1017 sej per individual per year (Bachelor); 556.94×1020 sej/year per 428 316=1.30×1017 sej per individual per year (no degree). The total emergy of knowledge contribution of all staffs in Mai Po is, 26.75×1017×3+1.57×1017×3+1.30×1017×11= 99.26 sej/year. ______中国科技论文在线 P. Qin et al. / Ecological Engineering 16 (2000) 271–280 www.paper.edu.cn 279

Acknowledgements Huang, S.L., Odum, H.T., 1991. Ecology and economy: energy synthesis and public policy in Taiwan. J. Environ. Manage. 32 (4), 313–334. We thank Mai Po Natural Reserve who sup- Jansson, A.M., 1984. Integration of economy and ecology — ports the raw data about waterfowl count, num- an outlook for the eighties. Asko Laboratory, University ber of tourists and training member, the of Stockholm, Stockholm. production of shrimps and fishes, etc. We also Jorgenson, S.E., Nielsen, S.N., Mejer, H., 1995. Emergy, thank the Education and Manpower Bureau, environ, exergy and ecological modelling. Ecol. Model. 77 Government Secretariat, Hong Kong provided (2–3), 99–109. Lan, S., Odum, H.T., 1994. Emergy evaluation of the environ- the population situation of Scientific degree in ment and economy of Hong Kong. J. Environ. Sci. 6 (4), Hong Kong. 432–439. Lee, S.Y., 1986. The intensity and consequences of herbivory on Kandelia candel(L.) druce leaves at the Mai Po marshes, References Hong Kong. In: Moton, B. (Ed.), Proceedings of the Second International Marine Biological Workshop: The Marine Flora and Fauna of Hong Kong and Southern Anderson, C., 1992. Primary production in Kandelia candel in China, Hong Kong, 1986. Hong Kong University Press. Hong Kong: a comparison of methods. Columbus ’92 Lee, S.Y., 1989a. Litter production and turnover of the man- Intecol’s IV Wetland Conference. Ohio State, University of Columbus, Ohio, USA. grove Kandelia candel(L.) druce in a Hong Kong tidal Aspinwall et al., 1996. Study on the ecological value of fish shrimp pond. Estuar. Coast. Shelf Sci. 29, 75–87. pond in Deep Bay area — technical paper. Report to the Lee, S.Y., 1989b. The importance of sesarminae crabs Chiro- Planning Department, Hong Kong. manthes spp. and inundation frequency on mangrove Kan- Axell, H., 1983. Mai Po marshes — proposal for development delia candel(L.) druce leaf litter turnover in a Hong Kong as a nature reserve and education center. Report to World tidal shrimp pond. J. Exp. Mar. Biol. Ecol. 131, 23–43. Wildlife Fund, Hong Kong. Lee, S.Y., 1990a. Net aerial primary productivity, litter pro- Bastianoni, S., Marchettini, N., 1996. Ethanol production duction and decomposition of the reed Phragmites commu- from biomass: analysis of process efficiency and sustain- nis in a nature reserve in Hong Kong: management ability. Biomass Bioenergy 11 (5), 411–418. implications. Mar. Ecol. Prog. Ser. 66, 161–173. Brown, M.T., McClanahan, T.R., 1996. Emergy analysis per- Lee, S.Y., 1990b. Primary productivity and particulate organic spectives of Thailand and Mekong River dam proposals. matter flow in an estuarine mangrove-wetland in Hong Ecol. Model. 91 (1–3), 105–130. Kong. Mar. Biol. 106, 453–463. Chalmers, M.L., 1989. International Waterfowl Count in Deep Li, Y.S., Lee, J.H.W., 1996. Hydraulics of Deep Bay and Tolo Bay, Hong Kong. Hong Kong Bird Report 1988, pp. Harbour. In: Civil Engineering Office, Civil Engineering 37–42. Department of Hong Kong Government (Eds.), Coastal Chalmers, M.L., 1990. International Waterfowl Count in Deep Infrastructure Development in Hong Kong, A Review. Bay, Hong Kong. Hong Kong Bird Report 1989, pp. Proceedings of the Symposium on Hydraulics of Hong 34–38. Kong Waters held in Hong Kong on 28–29 November Chalmers, M.L., 1992. International Waterfowl Count in Deep 1995. Bay, Hong Kong. Hong Kong Bird Report 1991, pp. Melville, D.S., Morton, B., 1983. Mai Po marshes. Hong 72–78. Kong WWF HK. Chiu, T.N., So, C.L., 1986. A Geography of Hong Kong. Nelson, J.G., 1993. Conservation and use of the Mai Po Oxford University Press, Hong Kong. marshes, Hong Kong. Nat. Areas J. 13 (3), 215–219. Day, J.W., Martin, J.F., Cardoch, L., Templet, P.H., 1997. Odum, H.T., 1983. Maximum power and efficiency — a System functioning as a basis for sustainable management rebuttal. Ecol. Model. 20 (1), 71–82. of deltaic ecosystems. Coast. Manage. 25 (2), 115–153. Odum, H.T., 1984. Energy analysis evaluation of coastal alter- Eum, K.H., Son, J.H., Cho, E.I., Lee, S.M., Park, C.K., 1996. natives. Water Sci. Technol. 16 (3–4), 717–734. The estimation of carrying capacity in Deukryang Bay by Odum, H.T., 1988. Self-organization, transformity, and infor- emergy analysis. J. Korean Fisheries Soc. 29 (5), 629–636. mation. Science 242, 1132–1139. Gunderson, L., 1989. Emergy Analysis of Everglades National Odum, H.T., 1996. Environmental Accounting—Emergy and Park in1989. Special Class Report. Center for Wetlands, Environmental Decision Making. Wiley, New York, pp. University of Florida, Gainesville, 14 pp. 73–87, 117–121, 231–232, 311. Homer, M., 1977. Seasonal abundance, biomass, diversity, and Patten, B.C., 1995. Network integration of ecological extremal trophic structure of fish in a salt marsh tidal creek affected principles: exergy, emergy, power, ascendancy, and indirect by a coastal power plant. In: Thermal Ecology, vol. 2. effects. Ecol. Model. 79 (1–3), 75–84. Division Technical Information Energy Research and De- Poovachiranon, S., 1986. The food of Chiromanthes bidens and velopment Administration, Oak Ridge, TN, pp. 259–267. C. maipoensis in Hong Kong. In: Moton, B. (Ed.), Pro- 280 ______中国科技论文在线 P. Qin et al. / Ecological Engineering 16 (2000) 271–280 www.paper.edu.cn

ceedings of the Second International Marine Biological The Nature Conservation Bureau and Wetlands Advisory Workshop: The Marine Flora and Fauna of Hong Kong Service, 1997. Conservation Strategy and Management and Southern China, Hong Kong, 1986. Hong Kong Uni- Plan: Final Report. versity Press. Tiezzi, E., Bastianoni, S., Marchettini, N., 1996. Environmen- Sohn, J.H., Shin, S.K., Cho, E.I., Lee, S.M., 1996. Emergy tal cost and steady state: the problem of adiabaticity in the analysis of Korean fisheries. J. Korean Fisheries Soc. 29 emergy value. Ecol. Model. 90 (1), 33–37. (5), 689–700. Tong, S.S., 1996. Ecological evaluation of alternative wetland Tam, N.F.Y., Vrijmoed, L., Wong, Y.S., 1990. Nutrient dy- management. First International Conference of Ecological namics associated with leaf decomposition in a small sub- Engineering, 1996, Beijing. tropical mangrove community in Hong Kong. Bull. Mar. Ulgiati, S., Odum, H.T., Bastianoni, S., 1994. Emergy use, Sci. 47 (1), 68–78. environmental loading and sustainability: an emergy analy- Tam, N.F.Y., Wong, Y.S., Lan, C.Y., Wang, L.N., 1998. sis of Italy. Ecol. Model. 73 (3–4), 215–268. Litter production and decomposition in a subtropical man- Young, L., Chan, G., 1997. The significance of drained fish grove swamp receiving wastewater. J. Exp. Mar. Biol. ponds for wintering waterbirds at the Mai Po marshes, Ecol. 226, 1–18. Hong Kong. IBIS 139 (4), 694–698.