Aggregate Characteristics During Natural Revegetation on the Loess Plateau

Field investigations and laboratory analysis were conducted to study the characteristics of soil water-stable aggregates during vegetation rehabilitation in typical grassland soils of the hilly-gullied loess area. The relationship between water- stable aggregates and other soil properties was analyzed using canonical correlation analysis and principal component analysis. The results show that during the natural revegetation, the aggregates 〉 5 mm dominated and constituted between 50% and 80% of the total soil water-stable aggregates in most of the soil layers. The 2-5 mm aggregate class was the second main component. The mean value of water-stable aggregates 〉 5 mm within the 0-2 m soil profile under different plant communities decreased in the following order： Stipa grandis 〉 Stipa bungeana Trin. 〉 Artemisia sacrorum Ledeb. 〉 Thymus mongolicus Ronn. 〉 Hierochloe odorata （L.） Beauv. Clay, organic matter, and total N were the key factors that influenced the water stability of the aggregates. Total N and organic matter were the main factors that affected the water stability of the aggregates 〉 5 mm and 0.5-1 mm in size. The contents of Fe2O3, Al2O3, and physical clay （〈 0.01 mm） were the main factors which affected the water stability of the 1-2 and 0.25-0.5 mm aggregates.

SLOPE LITHOLOGIC PROPERTY, SOIL MOISTURE CONDITION AND REVEGETATION IN DRY-HOT VALLEY OF JINSHA RIVER

The dry-hot valley of the Jinsha River is one of the typical eco-fragile areas in Southwest China, as well as a focus of revegetation study in the upper and middle reaches of the Changjiang River. Due to its extremely dry and hot climate, severely degraded vegetation and the intense soil and water loss, there are extreme difficulties in vegetation restoration in this area and no great breakthrough has ever been achieved on studies of revegetation over the last several decades. Through over ten years’ research conducted in the typical areas-the Yuanmou dry-hot valley, the authors found that the lithologic property is one of the crucial factors determining soil moisture conditions and vegetation types in the dry-hot valley, and the rainfall infiltration capability is also one of the key factors affecting the tree growth. Then the revegetation zoning based on different slopes was conducted and revegetation patterns for different zones were proposed.

Preliminary assessment of revegetation potential through ryegrass growing on bauxite residue

Bauxite residue(BR),a by-product of the industrial production of alumina,has raised environmental concerns in the last decades,due to the presence of high amounts of alkali and various heavy metal ions.Limited studies on the application of abandoned BR with massive consumption have been reported.In this study,the possibility of the revegetation using ryegrass growing on BR was discussed mainly through the growth indications and transfer of heavy metal ions in BR and plants.In the pot trails,ryegrass was seeded on BR,de-alkali BR,with(DBRO)or without(DBR)organic fertilizer,respectively.The results indicated that the remediation of bauxite residue can be achieved through de-alkali with acid neutralization.Elemental analysis indicated that the elements,except for Fe,Mn and Pb,were stable in plant roots,and ryegrass could hardly absorb Cd.But,some heavy metals such as Cu enriched in plants,which should be noted in revegetation on bauxite residue.

Assisted Revegetation Following Contaminated Site Remediation in the Arctic: Four-Year Case Study of a Former Radar Site

Cape Dyer (DYE-M), located on the easternmost point of Baffin Island, is a former DEW line radar station built in 1956-57 which was upgraded in 1993 as part of the current North Warning System. Environmental studies in the late 1990s and early 2000s determined that extensive soil contamination existed across the site, and excavation of six landfills and subsequent reshaping of the area in 2008 disturbed approximately 19,700 m2. A four-year pilot project was conducted between 2009 and 2012 to investigate feasibility of, and determine methods to, accelerate revegetation of the disturbed area through assisted seed dispersal of native and non native species and selective transplantation of slow-growing shrub species. Prior to revegetation efforts, plant surveys conducted in July 2009 determined that 15 species were present in the undisturbed areas, of which Salix arctica (~11%), Vaccinium uliginosum L. (~8%), and Empetrum nigrum L. (~5%) were the predominant species. A total of 14 species (three new) were observed growing on the disturbed areas between 2010 and 2012. The majority of Lolium multiflorum (annual ryegrass) seeds planted as a nurse species in 2009 grew in 2010, but most were stunted and only observed in furrows or sheltered areas at a low density. Salix arctica Pall. (willow) cuttings planted in “islands” of 20-30 cuttings in fall 2009 had a three-year survival rate of 82%, while a second set of cuttings planted in fall 2011 had a one-year survival rate of 93%. Visual observations indicate that patches of new vegetation are becoming more predominant on the disturbed area, especially around the willow islands, indicating the importance of microtopography for successful reclamation in arctic environments. Monitoring over ten or more years will be required to determine the long term success of this project.

Arbuscular Mycorrhizal Technology in Reclamation and Revegetation of Coal Mine Spoils under Various Revegetation Models

Reclamation and revegetation of a coal mine spoils with various revegetation models utilizing the mycorrhizal technology were studied. The models with different combination of plant species were designed to test the hypothesis of speedy revegetation. Root colonization and spore density of arbuscular mycorrhizae (AM) were lowest in plants seeded directly on slopes of the overburden (coal mine dump). At flat surfaces, the mycorrhizal colonization in plant species was higher than that observed at slopes. In other revegetation models, i.e., tree monoculture, tree monoculture + crop species (agroforestry), and two strata plantations (combination of different plant species), maximum AM colonization was recorded for tree species grown along with crop species. This was followed by two strata plantations and tree monoculture. In two strata plantations three categories of AM associations were recognized: 1) every plant in the combination, possessed high mycorrhizal association, 2) only one plant in the combination possessed high mycorrhizal association, and 3) none of the plants in the combination possessed high mycorrhizal association. Azadirachta indica, Pongamia pinnata, Leucaena leucocephala and Acacia catechu were most effective in catching mycorrhizae, and can be used as the effective tool in rehabilitation of the degraded ecosystems.

Metal concentrations and mycorrhizal status of plants colonizing copper mine tailings: potential for revegetation

A field survey of metal concentrations and mycorrhizal status of plants growing on copper mine tailings was conducted in Anhui Province, China. Available phosphorus and organic matter in the tailings were very low. High concentrations of Pb, Zn, As and Cd as well as Cu were observed on some sites. The dominant plants growing on mine tailings belonged to the families Gramineae and Compositae, and the most widely distributed plant species were Imperata cylin-drica, Cynodon dactylon and Paspalum distichum. Coreopsis drummondii also grew well on the arid sites but not on wet sites. Very low or zero arbuscular mycorrhizal (AM) fungal colonization was observed in most of the plants, but extensive mycorrhizal colonization was recorded in the roots of C. drummondii and C. dactylon. Metal concentrations in plant tissues indicated that /. cylindrica and P. distichum utilized avoidance mechanisms to survive at high metal concentrations. The investigation suggests that remediation and revegetation of heavy metal contaminated sites might be facilitated by selection of tolerant plant species. Isolation of tolerant AM fungi may also be warranted.

Impacts of revegetation management modes on soil properties and vegetation ecological restoration in degraded sandy grassland in farming-pastoral ecotone

Focusing on the impact of various vegetation management modes on sandy grassland's soil property and vegetation ecological restoration of farming-pastoral ecotone,field surveys and lab analysis were conducted to study the correlation between the characteristics of soil properties and vegetation ecological restoration under four different vegetation management modes,i.e.,unenclosed natural restoration,enclosed natural restoration,unenclosed artificial restoration and enclosed artificial restoration,which have a restoration history of 15 years in the southern edge of the degraded sandy land area of Mu Us Desert in Leilongwan Town,Hengshan County,Shaanxi Province.After 15 years of vegetation restoration,these four vegetation management modes all proved to be useful for improving the vegetation ecological restoration and the soil quality of the degraded sandy grassland not only by enhancing the aboveground vegetation height,coverage and biomass but also increasing the content of soil clay,organic matter,CEC,total nitrogen,available nutrient while reducing soil bulk density.The vegetation ecological restoration effect and soil quality under enclosed or artificial restoration management are better than those of unenclosed or natural restoration management;and the most satisfactory vegetation ecological restoration effects and soil quality can be achieved under the integration of enclosed and artificial restoration management.Severely degraded sandy grassland,during the vegetation restoration,would form an interactional coordinating relationship with the vegetation and soil properties.Vegetation properties as height,coverage and biomass have significant positive correlations with organic matter,CEC,total nitrogen and available nitrogen,phosphorus,and potassium contained in soil.Only the adoption of the strict enclosure system,implementation of aggressive artificial vegetation restoration measures and the realization of the regurgitation-feeding policy of industry towards husbandry can guarantee the gradual restoration of degraded sandy grassland in farming-pastoral ecotone,so that it can continue to play the role of ecological protective screen.

A review on dump slope stabilization by revegetation with reference to indigenous plant

The waste,subgrade ROM and fine dumps of iron ore mines are characterized by high rock fragment contents,low moisture retention capacity,higher bulk density,low nutrients,lower pH and elevated metal concentrations.Use of suitable revegetation programme,that require the selection of right type of plants to be used vis-à-vis the site condition and characteristics,can enhance the long-term stability,both mechanical and ecological,of dumps(waste,subgrade ROM and fines)through providing vegetative cover to control soil erosion and gully formation,consolidation of dump top and side surfaces,binding the loose particles through intricate roof system,etc.This paper overviews the roles of revegetation programme that can be used where vegetation is considered to be the long-term answer to slope protection and erosion control.Various revegetation processes like Coir matting,lemon grass,vetiver grass and indigenous plant may find a wide range of usage in iron ore mines for dump stabilization.The Miyawaki method of plantation is more effective than the conventional method of plantation.This will lead to co-existence of plants,and as a matter of fact each plant draws from the other vital nutrients and they grow to become strong and healthy.The Miyawaki plantation technique aims at“survival of the fittest”,and the area which undergone such plantation has an ecology of their own.The indigenous plant has good binding capacity and helps to control soil erosion as well as improve the dump stability.These indigenous plant species include Shorea robusta(Sal),Dalbergia sisoo(Shisham),Karanj and Azadirachta(Neem).The growth of indigenous plants is dependent upon the soil quality as well as the organic matter of the dump material.The leaf debris plays an important role for improving the organic matter of the dump material to successfully implement the revegetation programme.

Not vegetation itself but mis-revegetation reduces water resources

Increasing greening of planet Earth to slow down the rise of atmospheric CO_(2) concentrations is certainly desirable;however,its consequences on water resources are less affirmative and thus are a matter of wide concern.China,as the largest and most successful country of the world in terms of artificial revegetation,is naturally the focus of the concerns and warnings.Based on previous studies,we analyzed the mechanism for the effects of climate and watershed characteristics on water resources,explained various hydrological results and phenomena,and considered the ways in which water consumption by artificial revegetation projects can be reduced.Moreover,some guidelines are suggested for artificial revegetation at watershed scale with consideration of water resource sustainability.The findings of this study highlight the need for more top-down approaches when studying the mechanism of"forest and water".

Balancing carbon and water for sustainable revegetation in the Loess Plateau

With the support by the National Natural Science Foundation of China and the Major Programme of High Resolution Earth Observation System,the research team led by Prof.Fu Bojie(傅伯杰)at the State Key Laboratory of Urban and Regional Ecology,Research Center for Eco-Environmental Sciences of Chinese Academy of Sciences,cooperated with the researchers from Peking University and the Laboratoire

Environmental Indicators Related to Native Plants to Assess the Quality of Life in the Degraded Desert Area

In Kuwait, the scarcity and irregularity of rainfall, the availability of areas of sand supply and the prevalence of strong north westerly winds significantly influence the stability of the fragile ecosystem. Naturally, grown native shrubs and trees can provide potential shelter to soil surface in desert areas. To study the environmental indicators provided by native plant and their ability to improve quality of life, the morphological properties of the vegetated nabkhas within different areas in Kuwait desert and within protected area were assessed. The vegetated dunes can trap maximum mobile sediments from 10.5 to 0.45 ton thus cost saving per plant estimated to be from 5.5 to 0.24 USD. The arrangements of the native plant from highest efficiency in absorbing carbon dioxides to the least were as follows: Nitraria retusa, Haloxylon salicornicum, Citrullus colocynthis, Tamarix aucheriana, Lycium shawii, Convolvolus oxyphyllus, Rhanterium epapposum, Panicum turgidum, Calligonum polygonoides, Astragalus spinosus, Cyperus conglomerates. The cost saving of CO_(2) per year estimated to be from 0.95 to 1,542.1 USD. The revegetation enhanced physical and chemical quality of soil and created microenvironments for the flora and fauna. The aim of this paper is to identify the environmental indicators related to native plants for the assessment of quality of life.

Arbuscular mycorrhizal fungi ameliorate the chemical properties and enzyme activities of rhizosphere soil in reclaimed mining subsidence in northwestern China

In semi-arid region of northwestern China, underground mining subsidence often results in decreased vegetation coverage, impoverishment of soil fertility and water stress. In addition, the physical-chemical and biological properties of soil also change, resulting in more susceptible to degradation. In particular, subsidence causes disturbance of the symbioses of plant and microbe that can play a beneficial role in the establishment of vegetation communities in degraded ecosystems. The objective of this study was to evaluate the effects of revegetation with exotic arbuscular mycorrhizal fungi(AMF) inoculum on the chemical and biological properties of soil over time in mining subsidence areas. Soils were sampled at a depth up to 30 cm in the adjacent rhizosphere of Amorpha fruticose Linn. from five reclaimed vegetation communities in northwestern China. In August 2015, a field trial was set up with five historical revegetation experiments established in 2008(7-year), 2011(4-year), 2012(3-year), 2013(2-year) and 2014(1-year), respectively. Each reclamation experiment included two treatments, i.e., revegetation with exotic AMF inoculum(AMF) and non-AMF inoculum(the control). Root mycorrhizal colonization, glomalin-related soil protein(GRSP), soil organic carbon(SOC), soil nutrients, and enzyme activities were also assessed. The results showed that mycorrhizal colonization of inoculated plants increased by 33.3%–163.0% compared to that of non-inoculated plants(P<0.05). Revegetation with exotic AMF inoculum also significantly improved total GRSR(T-GRSP) and easily extracted GRSP(EE-GRSP) concentrations compared to control, besides the T-GRSP in 1-year experiment and the EE-GRSP in 2-year experiment. A significant increase in SOC content was only observed in 7-year AMF reclaimed soils compared to non-AMF reclaimed soils. Soil total N(TN), Olsen phosphorus(P) and available potassium(K) were significantly higher in inoculated soil after 1–7 years of reclamation(except for individual cases), and increased with reclamation time(besides soil Olsen P). The exotic AMF inoculum markedly increased the average soil invertase, catalase, urease and alkaline phosphatase by 23.8%, 21.3%, 18.8% and 8.6%, respectively(P<0.01), compared with the control. Root mycorrhizal colonization was positively correlated with soil parameters(SOC, TN and soil available K) and soil enzyme activities(soil invertase, catalase, urease and alkaline phosphatase) in both AMF and non-AMF reclaimed soils(P<0.05), excluding availableK in non-AMF reclaimed soils. T-GRSP(P<0.01) and EE-GRSP(P<0.05) were significantly correlated with the majority of edaphic factors, except for soil Olsen P. The positive correlation between root mycorrhizal colonization and available K was observed in AMF reclaimed soils, indicating that the AMF reclaimed soil with a high root mycorrhizal colonization could potentially accumulate available K in soils. Our findings concluded that revegetation with exotic AMF inoculum influenced soil nutrient availability and enzyme activities in the semi-arid ecosystem, suggesting that inoculating AMF can be an effective method to improve soil fertility and support restoration of vegetation communities under poor conditions like soil nutrient deficiency and drought.

Effects of Grassland Degradation and Re-vegetation on Carbon and Nitrogen Storage in the Soils of the Headwater Area Nature Reserve on the Qinghai-Tibetan Plateau,China

Both overgrazing and climate change contribute to grassland degradation in the alpine regions of China and negatively affect soil carbon and nitrogen pools. We quantified changes in soil organic carbon （SOC） and total nitrogen （TN） in black soil beach （BSB）. We measured SOC and TN in severely degraded and non-degraded grasslands to calculate differences in carbon and nitrogen storage, and field survey results were extrapolated to the entire headwaters area of the Qinghai-Tibetan Plateau （36.3xlos krn~） to determine SOC and TN losses from these grasslands. We also evaluated changes in SOC and TN in severely degraded grasslands that were artificially re-vegetated five, seven and nine years ago. Totally 92.43 Tg C and 7.08 Tg N were lost from the BSB in the headwater area, which was approximately 50% of the original C and N soil pools. Re-vegetation of the degraded grasslands in the headwater area would result in a gain of 32.71 Tg C in the soil after five years, a loss of 5.5a Tg C after seven years and an increase of 44.15 Tg C after nine years. The TN increased by 53.09% and 59.98% after five and nine years, respectively, while it decreased by 4.92% after seven years of re-vegetation. The results indicate that C and N stocks followed a ＂V＂ shaped pattern with re- vegetation time. Understanding plant-soil interactions during succession of artificially planting grassland ecosystems is essential for developing scientifically sound management strategies for the effectively re-vegetated BSB.

Changes in soil properties and erodibility of gully heads induced by vegetation restoration on the Loess Plateau, China

Soil erosion on the Loess Plateau of China is effectively controlled due to the implementation of several ecological restoration projects that improve soil properties and reduce soil erodibility. However, few studies have examined the effects of vegetation restoration on soil properties and erodibility of gully head in the gully regions of the Loess Plateau. The objectives of this study were to quantify the effects of vegetation restoration on soil properties and erodibility in this region. Specifically, a control site in a slope cropland and 9 sites in 3 restored land-use types （5 sites in grassland, 3 in woodland and 1 in shrubland） in the Nanxiaohegou watershed of a typical gully region on the Loess Plateau were selected, and soil and root samples were collected to assess soil properties and root characteristics. Soil erodibility factor was calculated by the Erosion Productivity Impact Calculator method. Our results revealed that vegetation restoration increased soil sand content, soil saturated hydraulic conductivity, organic matter content and mean weight diameter of water-stable aggregate but decreased soil silt and clay contents and soil disintegration rate. A significant difference in soil erodibility was observed among different vegetation restoration patterns or land-use types. Compared with cropland, soil erodibility decreased in the restored lands by 3.99% to 21.43%. The restoration patterns of Cleistogenes caespitosa K. and Artemisia sacrorum L. in the grassland showed the lowest soil erodibility and can be considered as the optimal vegetation restoration pattern for improving soil anti-erodibility of the gully heads. Additionally, the negative linear change in soil erodibility for grassland with restoration time was faster than those of woodland and shrubland. Soil erodibility was significantly correlated with soil particle size distribution, soil disintegration rate, soil saturated hydraulic conductivity, water-stable aggregate stability, organic matter content and root characteristics （including root average diameter, root length density, root surface density and root biomass density）, but it showed no association with soil bulk density and soil total porosity. These findings indicate that although vegetation destruction is a short-term process, returning the soil erodibility of cropland to the level of grassland, woodland and shrubland is a long-term process （8-50 years）.

Salt ions accumulation and distribution characteristics of pioneer plant species at a bauxite residue disposal area, China

Bauxite residue disposal areas(BRDAs)are physically degraded and hostile to plant growth.Nevertheless,natural plant colonization was observed in an abandoned BRDA in Central China.The pioneer plant species at the disposal area were identified,whilst distribution characteristics of salt ions such as Na^+,K^+,and Ca^2+in plant tissues and rhizosphere residues were investigated.The mean concentration of exchangeable Na^+in the rhizosphere soils was 19.5 cmol/kg,which suggested that these pioneer plants had relatively high salinity resistance.Sodium content varied from 0.84 cmol/kg(Digitaria sanguinalis)to 39.7 cmol/kg(Kochia scoparia),whilst K to Na ratio varied from 0.71(Myricaria bracteata)to 32.39(Digitaria sanguinalis)in the shoots,which demonstrated that the salinity tolerance mechanisms of these pioneer species differed significantly.Accumulation factors of Na^+in local plant species ranged from 0.04(D.sanguinalis)to 3.29(M.bracteata),whilst the translocation factor varied from 0.13(D.sanguinalis)to 2.92(M.bracteata).The results suggested that four pioneer plant species including K.scoparia,M.bracteate,Cynodon dactylon and D.sanguinalis could be suitable for revegetation at other disposal areas.

Grazing alters sandy soil greenhouse gas emissions in a sand-binding area of the Hobq Desert,China

Deserts are sensitive to environmental changes caused by human interference and are prone to degradation.Revegetation can promote the reversal of desertification and the subsequent formation of fixed sand.However,the effects of grazing,which can cause the ground-surface conditions of fixed sand to further deteriorate and result in re-desertification,on the greenhouse gas(GHG)fluxes from soils remain unknown.Herein,we investigated GHG fluxes in the Hobq Desert,Inner Mongolia Autonomous Region of China,at the mobile(desertified),fixed(vegetated),and grazed(re-desertified)sites from January 2018 to December 2019.We analyzed the response mechanism of GHG fluxes to micrometeorological factors and the variation in global warming potential(GWP).CO_(2)was emitted at an average rate of 4.2,3.7,and 1.1 mmol/(m^(2)•h)and N_(2)O was emitted at an average rate of 0.19,0.15,and 0.09μmol/(m^(2)•h)at the grazed,fixed,and mobile sites,respectively.Mean CH_(4) consumption was as follows:fixed site(2.9μmol/(m^(2)•h))>grazed site(2.7μmol/(m^(2)•h))>mobile site(1.1μmol/(m^(2)•h)).GHG fluxes varied seasonally,and soil temperature(10 cm)and soil water content(30 cm)were the key micrometeorological factors affecting the fluxes.The changes in the plant and soil characteristics caused by grazing resulted in increased soil CO_(2)and N_(2)O emissions and decreased CH_(4) absorption.Grazing also significantly increased the GWP of the soil(P<0.05).This study demonstrates that grazing on revegetated sandy soil can cause re-desertification and significantly increase soil carbon and nitrogen leakage.These findings could be used to formulate informed policies on the management and utilization of desert ecosystems.

Sustainable reclamation practices for a large surface coal mine in shortgrass prairie,semiarid environment(Wyoming,USA):case study

Sustainable reclamation practices for large surface coal mines in USA semiarid environment contribute to the quality of the environmental on a long term basis where environmental resources are protected for future generation.Land,after reclamation,must be suitable for the previous use of greatest economic or social values to the community area.In the semiarid climate of USA,non-developed land is mainly utilized for crops,grazing,and wildlife.Completion of various stages of the reclamation processes includes verifcation and approval of reclamation criteria and performance standards created by state agencies.The sustainable reclamation practices were investigated at the USA’s largest surface coal mine of the semiarid environment in Wyoming.These practices include building post-mining topography to the approximate original contour and reestablish a stable hydrologic system to drain surface water.All available spoil material is backflled and graded to achieve the post-mining topography which closely resembles the pre-mining topography.No overburden material or other coal waste material is left in stockpiles at the mine.Detailed planning until the end of mining,the knowledge of available volumes of suitable backfll material and soil is necessary for sustainable management practices.Diverse and permanent vegetation capable of stabilizing soil surfaces and capable of self-regeneration is established.Sustainable management of the reclamation efort is achieved by enforcement processes developed by the state and federal agencies.Monthly inspections of mining and reclamation operations and reviews of annual reports submitted by the operator help determine if the reclamation processes are occurring according to the permit plan.

Canada Thistle (Cirsium arvense) Response to Clipping and Seeding of Competitive Grasses

Chemical restrictions, ecological concerns, liability issues, and public sentiment present challenges to land managers attempting to control highly invasive plants like Canada thistle (Cirsium arvense [L.] Scop.). Although herbicide application can be an effective control strategy, increasing limitations force managers of sensitive environments (e.g., national parks, wildlife refuges, protected water-bodies or waterways) to search for effective control alternatives. A greenhouse study was conducted to test the effectiveness of clipping (to simulate field mowing) and grass seeding as alternatives for Canada thistle control. Two native North American grasses (western wheatgrass [Pascopyrum smithii {Rydb.} A. L?ve] and streambank wheatgrass [Elymus lanceolatus {Scribn. & J.G. Sm.}Gould ssp. lanceolatus]) and one sterile hybrid cross between common wheat (Triticum aestivum L.) and tall wheatgrass (Thinopyrum ponticum [Podp.] Z.W. Liu & R.C. Wang) called RegreenTM were used. The effects of clipping and grass seeding on Canada thistle growth, and the effect of Canada thistle on grass growth, were evaluated using 14 unique treatments applied to potted Canada thistle and grass plants. Clipping inhibited Canada thistle growth (by 60%), while grass seeding had no effect. Presence of Canada thistle inhibited grass growth for all seeding treatments except when RegreenTM and western wheatgrass were seeded together with Canada thistle. Planting multiple species for restoration of Canada thistle-infested sites may be important (RegreenTM + western wheatgrass treatment), and cutting Canada thistle may be useful for reducing its growth in restored areas.

Column Analyses of Chloride Breakthrough and Lead Retention in Amended Sandy Soils

Stormwater quality design manuals lack scientifically creditable bases for many novel LID （Low-Impact Development） designs presently proposed to meet stormwater runoff management requirements. Potential stormwater pollutant adsorption and infiltration enhancement capabilities of forest-derived by-products （e.g. woodchips, bio-char） provide an opportunity to combine these readily availability materials into stormwater quality designs. On-site stormwater runoff treatment through determination of the soil-water transport and lead （Pb） retention capacity of two sandy soils from Oregon is considered. Using synthetic stormwater （-120 mg CI/L and -5 mg Pb/L） displacement tests in pairs ofABS （Acrylonitrile butadiene styrene） soil columns （75 mm dia by 0.46 m tall） with upward flow （to minimize air entrapment） saturated hydraulic conductivity, chloride dispersion and Pb retention by plain and amended soils is evaluated. Generally, soil amendment incorporation （woodchips, compost or biochar） as compared to an amendment layer resulted in improved hydraulic conductivities as compared to that of the soil alone. Chloride breakthrough curves verified that resident soil-water displacement occurred with 0.9 to 1.6 pore volumes and residence times for most columns were 15-30 minutes. No synthetic stormwater Pb ＂breakthrough＂ within the displaced or replaced soil-water was found, rather most Pb was adsorbed within the first 150 mm of soil.

Effect of Wood Compost on Extreme Soil Characteristics in the Lusatian Lignite Region

Open-cast lignite mining operations result in a loss of soil quality. Soils associated with coal mining are usually characterised by poor physical and chemical parameters. Low pH and heavy metal toxicity are of the main concerns. The lignite and pyrite content of the dump materials of the Lusatian open-cast mining district in Eastern Germany resulted in high acidification potential and low organic matter content of soils. These extreme conditions require considerable amounts of alkaline materials like compost to enable revegetation. This study was carried out to evaluate the effect of different application rates of wood compost on soil physico-chemical properties in two representative soil substrates (tertiary and quaternary) and on some plant growth parameters. Soil in each site was mixed with wood compost and sown with a grass mixture. The data of both studied soils showed an improvement in physical properties such as water holding capacity and bulk density in soil ameliorated with compost. Most soil chemical properties were increased significantly with the increase of compost application rates, particularly organic matter content, total nitrogen and cation exchange capacity. Compared to the control treatment in each site, the treated soil with compost showed a significant increase in grass biomass (fresh and dry matter yield). The results of these experiments revealed that addition of wood compost had significant positive effects on the soil physical and chemical properties, which affected the response of plant growth and can facilitate the revegetation of substrates contaminated with coal spoil.