The Research On Ecological Restoration And Its Ecological Benefits In XianTan Manganese Mining Wasteland

Xiangtan manganese Mine area habitats were destroyed seriously by the manganese mining and slag heap, fragmented into remnant pitches, geological structures destroyed, biodiversity decreased, and serious soil and water polluted, which led to serious heavy metal pollution of food, vegetables, water. For the restoration of the polluted environment, from 2010 the project term had been implementing ecological restoration test project, and continuous monitoring of the benefits of ecological restoration for four years. From the ecological point of view, we compared artificial ecological restoration and different periods of naturalrestoration about their ecological benefits and features, with main conclusions being achieved as follows:(1)According to different field types of ecological restoration:Artificial ecological restoration had dealt the gentle slopes became the 3 slope aspects and 2 surface slopes and vegetation reconstruction, Steep slopes field restoration mainly set up ecological interception system supplemented by soil and water conservation measures and vegetation reconstruction.By the RUSLE model analyzing, before artificial ecological restoration the erosion modulus in areas of gentle slope was 2560.01t · hm-2· a-1 in study area, belongs to moderate erosion level. The erosion modulus in areas of steep slopes was 5504.90t · hm-2· a-1 belongs to the intensity of erosion levels, after restoration the erosion modulus of gentle slope became 62.19t · hm-2· a-1, and theerosion modulus of steep slopes became 130.61t · hm-2· a-1 in study area.Erosion had been controlled in the microlevel. Soil erosion degree of wasteland was from micro level erosion to the intensity of erosion (203.91～5504.90 t, hm-2·a-1) before restoration, and after artificial restoration, erosion modulus can be greatly reduced to micro levelerosion.(2)Different years of the natural recovered area in study area which have total of 17 species, belonging to 15 families and 17 genera, characterized by more herb plants, less shrubs. The artificial ecological restoration of plant communities included the 2004plantation and the 2010plantation in a total have 36 species belonging to 33 genera and 22 families, characterized by more trees. By analysis the Margalef index, the Simpson index and the Shannon-Wiener index in a biodiversity, the result shows that natively secondary forest higher than plantations significantly, and plantations higher than natural ecological restoration significantly.By analysis of the βws、βR、βT、 βcin the two properties and the Csnumber data of β diversity, the result show that the degree of similarity of natural secondary forest communities is:2004plantation t>2010plantation>40 years natural recovered area>30 years natural recovered area>20 years natural recovered area>10yearsrecovered area. The CNnumber data of β diversity shows:2004plantation>2010plantation>40 years natural recovered area>10 years natural recovered area>30 years natural recovered area>20yearsrecovered area. CMHnumber data of β diversity shows:20yearsrecovered area>40 years natural recovered area>30 years natural recovered area>2004plantation>10 years natural recovered area>2010plantation. The CNnumber data of β diversity shows: 2004plantation>2010plantation>40 years natural recovered area>10 years natural recovered area>20 years natural recovered area>30yerasrecovered area.(3)Soil nutrients in total phosphorus, total nitrogen, total potassium and organic matter content in plantations higher than natural recovered plant communities significant. The organic matter in 2004 plantation is similar to the natively secondary forest. By the analysis of soil texture we knowthe soil in artificial ecological restoration and 40 years of natural recovery belongs silt clay loam, which more suitable for plants growing. By the analysis of soil physical properties we know the different of soil density about artificial ecological restoration and natural recovery is not significant, but the different of the capillary porosity, the total porosity, the maximum water holding capacity and the field water capacity in artificial ecological restoration and natural recovery are significant. The Mn, Fe and Zn content in the artificial ecological restoration are lower than natural recovery soil significant. By the analysis of Grey correlation degree, the result shows that the trends of correlation degree of plants diversity and soil physical properties show that:the field water capacity>the total porosity>capillary porosity>capillary water holding capacity>maximum water holding capacity>soil density. The trends of correlation degree of plants diversity and soil chemical properties show that:total nitrogen>total potassium>organic matter content>total phosphorus>pH>total Mn>total Fe>total Mg>total Zn>Total Cu>total Pb>total Cd.(4)2004 plantation canopy interception on precipitation interception rates between 5.88%～64.28% in near four years. The penetration waterswere between0.81%～92.84%. The stem flows werebetween0.60%-2.31%. All of them had annual and seasonal variations significant. The pH value of average annual rainfall outside the forest order was:2010> 2012> 2011> 2013. From outside rainfall to the forest penetration water and then to stemflows the pH value decreased. Ca is the highest monthly average content and P is the minimum in macro-elements of outside rainfall, the forest penetration waters and the stemflows.The highest monthly average concentration of micro-elements was Mn, minimum was Pb. The characteristics of penetration of water was:K is the highest monthly average content inmacro-elements, and the highest monthly average concentration of micro-elements was Mn. The maximum annual amount of leaching is Fe and Mn elements insoil Water penetration.(5)Mn content in different parts of the body of Koelreuteria paniculata in 2004 plantation with descending order as follows:leaves>roots>bark> stems>branches. Mn content in different parts of the body of Elaeocarpus decipiens with descending order as follows:leaves> bark> branches>Roots> stems. Elaeocarpus decipiens have stronger enrichment capacity and transport capacity of Mn than Koelreuteria paniculata, Mn content in different parts of the body of Cinnamomum campHora in 2010 plantation with descending order as follows:Roots> leaves> branches>bark> stems. Mn content in different parts of the body of Paulownia in young forest with descending order as follows:Roots> leaves> branches> bark> stems. Paulownia has stronger enrichment capacity for Mn and Cinnamomum campHora has stronger transport capacity for Mn.The Mn content in the body of plants in wetlands with descending order as follows:Canna warscewiezii> Thalia dealbata> Boehmeria> Pontederia cordata> TypHa orientalis> Nerium oleander> Softstem bulrush> Iris germanica> Arundo donax> PHragmites australis. The biological transfer factor of Mn with descending order as follows:PHragmites australis> TypHa orientalis> Boehmeria> Softstem bulrush> Pontederia cordata> Thalia dealbata> Iris germanica> Arundo donax> Canna warscewiezii> Nerium oleander> Acorus calamus. The biological accumulation factor of Mn with descending order as follows:Canna warscewiezii> Thalia dealbata> Boehmeria> Pontederia cordata> TypHa orientalis> Softstem bulrush> Nerium oleander> Iris germanica> Acorus calamus> Arundo donax> PHragmites australis.