Flora Of Bryophyte-pteridophyte And Ecological Restoration Potential In The Lannigou Gold Deposit, Guizhou Province

Lannigou Gold Deposit(105°52.311′E,25°09.030′N) is a carlin goldmine,situated Zhenfeng County of Guizhou Province.It lies on the Yunnan-Ouizhou Plateau with altitudes 733m above sea level.There is a character that storage abundance but grade low, produce 6g gold will expend lton ore.Thus,the environment was polluted by heavy metals go with gold ore.Besides,biodiversity was destroyed by strip mining,most species do not inhabit in karst rocky desertification with mining.We investigated the bryophytes and pteridophytes at the early mining to record and conserve plant resources before environment was destroyed completely.Heavy metals were mensurated in bryophytes,pteridophytes and corresponding substrates for estimate their potential in ecological restoration. Moreover,study species diversity and control effect of mosses on biotic crusts of karst rocky desertification region.961 bryophyte samples were belonged to 197 species in 81 genera, 32 families.Thereinto 27 species are Hepaticae in 19 genera of 11 families,and 170 species are Musci in 63 genera of 20 families.339 pteridophyte samples were belonged to 36 species in 20 genera,14 families.Coefficient of similarity of bryophytes and pteridophytes in different habitat showed that family,genus and species comparability of bryophytes are lower than pteridophyte.Pottiaceae,Hypnaceae,Bryaceae and Ditrichaceae are dominant families in Lannigou Gold Deposit.Bryum Dill.,Fissidens Hedw., Philonotis Brid.,Weisia Hedw.,Hyophila Brid.and Pohlia Hedw.are dominant genera.The dominant families and genera of pteridophytes show that Pteris L.is adaptable inhabit in this region,especially Pteris vittata L..All the Life-forms of bryophyte samples have six types:short turfs,tall turfs,mats,wefts,cushions and pendants.Short turfs and wefts are dominant,which is an adaptability to especial environment in gold mine and karst rocky desertification.There are fourteen bryophyte phytogeogrphical elements in study region:Cosmopolitan,Pantropic,Tropical America and Tropic Asian disjuncted elements,Old World Tropics elements,Tropical Asian to Tropical Oceanian elements,Tropical Asia and Tropical Africa, Tropical Asia,North temperate zone,Eastern Asia and North America, Old World Temperate elements,Temperate Asian elements, Mediterranean,West Asia to Central Asia,Eastern Asia,Endemic to China.Pteridophyte phytogeogrphical elements only include six types: Pantropic,Tropical Asian to Tropical Oceanian elements,Tropical Asia,Temperate Asian elements,Eastern Asia,Endemic to China.Nine heavy metal elements' contents(Au,Cu,Zn,Pb,Cd,Cr,Co,As,Hg) of 8 samples:Pylaisiellapolysnths(Hedw.) Grout,Bryum pallescens Schleich.ex Schwaegr.var.pallescens,Ditrichum heteromallum(Hedw.)Britt.,Weisia planifolia Dix.,Weisia semipallida C.Muell.,Cyrto-hypnum versicolor(C.Muell.) Buck et Crum,Pteris vittata L.and Eupatorium adenophorum Spreng.and their substrates were determined by atomic absorption spectrometer and atomic fluorescence spectrometer.The result showed that average concentration of arsenic and hydrargyrum in substrate of bryophytes are 222.378mg/kg and 23.516mg/kg,respectively,which are 5.56 times and 15.68 times of the third class standard(40mg/kg for arsenic, 1.5mg/kgfor hydrargyrum) of National Environmental Quality Standard for Soil.The concentration of hydrargyrum and arsenic in substrate of Pteris vittata L.(As:717.844mg/kg,Hg:3.174mg/kg) and Eupatorium adenophorum Spreng.(As:666.021mg/kg,Hg:4.206mg/kg) are also high.The result indicated that the soil was polluted by heavy metals. Concentration of heavy metals in three plants and bioconcentration factor show that each species have tolerance for heavy metal,the detailed instance as follows:Pylaisiella polyantha(Hedw.) Grout for Cu,Zn,Cd,Cr,Co,Hg,Bryum pallescens Schleich.ex Schwaegr. var.pallescens for Cu,Zn,Cd,Cr,Co,Ditrichum heteromallum(Hedw.) Britt.for Cu,Zn,Pb,Cd,Co,Weisia planifolia Dix.for Zn,Cd,Cr,Weisia semipallida C.Muell.for Cu,Zn,Cd,Cr,Cyrto-hypnum versicolor(C.Muell.) Buck et Crum Zn,Cd,Cr,Co have accumulating ability.Therefore,all of 6 bryophytes in this study can be used in mine polluted by heavy metals as pioneer plants for ecological restoration in further research.Pteris vittata L.can tolerance Cr except arsenic,the concentration of Cr in the root,leafstalk and leatherleaf are 127.2mg/kg,98.47mg/kg,156.1mg/kg,and the corresponding bioconcentration factor are 2.835,2.195,3.48.The bioconcentration factor of root,stem and leaf of Eupatorium adenophorum Spreng.for Cr are 2.95,1.66,3.73.But compare the concentration of heavy metals and bioconcentration factor showed that bryophyte tolerance ability for the another 8 heavy metals obvious higher than Pteris vittata L.and Fupatorium adenophorum Spreng.except arsenic.Therefore,bryophyte and Pteris vittata L.is a perfect plant association as pioneer plants for ecological restoration in mine.In addition,the result showed that arsenic accumulation in Pteris vittata L.basically accord with the Chen Tongbin' s definition of Hyperaccumulator,but correspondingly lower arsenic concentration is absorbed in Pteris vittata L.from gold mine due to a variety of heavy metal coactivation.The study also found that bioconcentration factor is 0.6 in leatherleaf of Pteris vittata L.when arsenic concentration is 718mg/kg in mine soil.Therefore,arsenic critical concentra-tion is about 700 mg/kg in mine soil that may cause bioconcen-tration factor beginning decline from one in Pteris vittata L.for arsenic,but the result also need to be quantified by laboratory experiment.A determination of pedogenesis quantity,rate of saturated water adsorption and quantity of saturated water adsorption of the thirteen mosses.The results showe that average biomass from 161kg/hm~2 to 6690kg/hm~2,average pedogenesis quantity from 438kg/hm~2 to 18350kg/hm~2,average rate of saturated water adsorption from 780.43% to 1705.56%,the highest up to 2228.57%.And the average quantity of saturated water adsorption from 1256.5 kg/hm~2 to 18434.1kg/hm~2, the highest up to 68140.3kg/hm~2.Therefore,the results indicate that the moss crusts had a strong ability to absorb and reserve water.Besides,the moss crusts had a evidence ability to pedogenesis with biology,which is significant effect on rock desertification control in rocky desertification region which was produced by mining.