W.Shuwenetal./EcologicalEngineering18(2001)115–120119

3.2.Results

After4yearsofself-design,the240halalanggrasslandturnedintoareedwetland,asindicatedbytheplantcommunitycompositionofthetwoecosystems.Weevaluatedthisprojectbystudyingthefunctiontheecosystem,whichisprovidinghabitatforrarewaterfowl.Thenumbersandkindsofbirdsthatwinteredin1993and1998justinthis240halandwerecompared.

3.2.1.PlantcompositionandprimaryproductionFouryearsafterthewetlandwascreatedin1994,largeareasofreedgrewupinthewetland.Theplantcompositionchangedfromlalang,Chi-neseaeluropus(Aeluropussinensis)andreedtoalgae,cattail(Typhaangustifolia)andreed(Table1).TheplantcoverandprimaryproductionarealsolistedinTable1.Thetotalprimaryproduc-tionofthesystemincreasedby3.34timesasthegrasslandturnedintoareedwetland.

3.2.2.Winteringbirds

Manymorebirdswereobservedtowinterinthereedwetlandin1998thanthoseinlalanggrasslandin1993(Table2):thespeciesrichnessofwaterfowlincreasedfrom16to37;speciesunderChina’skeyprotectionincreasedfrom3to11.Thenumberofwaterfowlindividualsincreasedfrom3459to97747.Red-crownedcranesin-creasedby82%to545individuals,aboutonequarterofthetotalintheworld.

4.Conclusions

Inthisprojectofcreatinga240-hareedwet-land,wechoseapropersite,pumpedthewater,andgavenatureaworkingenvironmentwithoutanyfurtherhumanin uences.Allthatwedidwasintendedtomakegoodpreparationfornature’sself-design.Everystepwetookwasjudgedbytheprinciplesofecologicalsuccessiontoensurethedirectionofnature’swork.Wedidnotspendmuchtimeandfundsonimitatingtheenviron-mentalconditionsandcommunitystructureoftheoriginalkindofsystem.Weleftthisworktonaturewhilewefocusedonallowingnaturetodo

herwork.Theapplicabilityofsuchamethodforwetlandcreationwascon rmedbytheprojectinYanchengBiosphereReserve.Naturesurprisedusagainbyhergreatdesignability,suggestingweshouldpaymorerespecttoself-designthantohumandesigninourprojects.The

Table2

Birdswinteringinthe240halalanggrasslandin1993andinthereedwetlandin1998Speciesofbirds

Number1993

1998Grusjaponensis300545Grusgruslilfordi216Grusleucogeranus272Larussaundersi2410Larusargentatus0154Larusridibundus201300

Larusrelictus02Ardeacinerea

15145Mycticoraxnyticorax62Podicepsru collis6180Podicepscristatus024Podicepsnigricollis02Platalealeucorodia016Podicepsminor032Anseralbifrons02Ansererythropus011Ansercygnoides0754Anserfabalis983600Anseranser01750Othergeese

42400Cygnusc.cygnus04Phalacrocoraxcarbo0238Phalacrocoraxpelagicus020Anaspoecilorhyncha12005800Anasplatyrhynchos03600Anascrecca32012270Anaspenelope1002620Anasacuta04000Anasfalcata205400Tadornatadorna0800Mergusmerganser11100Mergussquamatus018Mergusalbellus02900Otherducks

30027000Numeniusarquata1120Tringaerythropus220Calidrisalpina

06700Recur6irostraa6osetta0120Otherbirds106012300Total

3459

96447