Topsoil Removal Research Articles

カラマツの天然更新施業のための表土除去が樹木の成長に与える影響 : 東神楽町での一例(会員研究発表論文)

カラマツの天然更新施業のための表土除去が樹木の成長に与える影響 : 東神楽町での一例(会員研究発表論文)

Heavy metals and trace elements in atmospheric fall-out: Their relationship with topsoil and wheat element composition

The objectives of this study were to determine the average concentrations and deposition rates of 28 elements in atmospheric bulk deposition and to elucidate associations among topsoil, bulk deposition and wheat element composition. The fluxes of arsenic (As), copper (Cu), lead (Pb) and zinc (Zn) deposition in Córdoba were higher than in other agro-ecosystems, which reflects both natural (geochemistry and topsoil removal) and anthropogenic sources. High lanthanide, uranium (U) and thorium (Th) concentrations revealed the impact of an open cast uranium mine. The highest enrichment factors (EF) were those of Cu, Pb, Zn and nickel (Ni), with calcium (Ca) being the most prominent in the surroundings of a cement plant. Industries and the transport of airborne urban pollutants were the main anthropogenic sources for Ca, Cu, Ni, Pb, Zn, cadmium (Cd), iron (Fe), manganese (Mn) and antimony (Sb). The concentrations of metals in wheat grain were predicted using the topsoil and atmospheric fall-out composition with R2=0.90, with the latter being the best explanatory variable. The present study highlights the potential health hazards of wheat consumption (Environmental Protection Agency) by the assessment of heavy metals in bulk atmospheric deposition.

Effects of Four Different Restoration Treatments on the Natural Abundance of 15N Stable Isotopes in Plants

δ15N signals in plant and soil material integrate over a number of biogeochemical processes related to nitrogen (N) and therefore provide information on net effects of multiple processes on N dynamics. In general little is known in many grassland restoration projects on soil–plant N dynamics in relation to the restoration treatments. In particular, δ15N signals may be a useful tool to assess whether abiotic restoration treatments have produced the desired result. In this study we used the range of abiotic and biotic conditions provided by a restoration experiment to assess to whether the restoration treatments and/or plant functional identity and legume neighborhood affected plant δ15N signals. The restoration treatments consisted of hay transfer and topsoil removal, thus representing increasing restoration effort, from no restoration measures, through biotic manipulation to major abiotic manipulation. We measured δ15N and %N in six different plant species (two non-legumes and four legumes) across the restoration treatments. We found that restoration treatments were clearly reflected in δ15N of the non-legume species, with very depleted δ15N associated with low soil N, and our results suggest this may be linked to uptake of ammonium (rather than nitrate). The two non-legume species differed considerably in their δ15N signals, which may be related to the two species forming different kinds of mycorrhizal symbioses. Plant δ15N signals could clearly separate legumes from non-legumes, but our results did not allow for an assessment of legume neighborhood effects on non-legume δ15N signals. We discuss our results in the light of what the δ15N signals may be telling us about plant–soil N dynamics and their potential value as an indicator for N dynamics in restoration.

礫河原におけるオオキンケイギク埋土種子の表土はぎとりによる除去効果

礫河原におけるオオキンケイギク埋土種子の表土はぎとりによる除去効果

Effect of past topsoil removal on the current distribution of threatened plant species in a moist tall grassland of the Watarase wetland, Japan: Mapping of selected sites for wetland restoration by topsoil removal

Effect of past topsoil removal on the current distribution of threatened plant species in a moist tall grassland of the Watarase wetland, Japan: Mapping of selected sites for wetland restoration by topsoil removal

オオキンケイギクが侵入した河川敷における表土はぎとりによる礫河原植生の再生効果

オオキンケイギクが侵入した河川敷における表土はぎとりによる礫河原植生の再生効果

INVESTIGATIONS ON RADIOACTIVE SUBSTANCES RELEASED FROM THE FUKUSHIMA DAIICHI NUCLEAR POWER PLANT

The Great East Japan Earthquake on March 11th, 2011, severely damaged the Fukushima Daiichi Nuclear Power Plant resulting in the diffusion of many radioactive substances throughout Fukushima prefecture. To examine these substances, we have carried out investigations for several months since immediately after the accident. We revealed that environmental high-level radiation spread northwesterly from the nuclear plant and several areas in Nakadori, the region located in the central part of the prefecture between Hamadori (east part of the prefecture) and Aizu-chihou (west part), was contaminated with mid-level radiation. We also analyzed radionuclides in soil and estimated future radiation levels.The importance of topsoil removal for decontamination has become an obvious countermeasure since many radioactive substances have settled on the surface. In addition, we investigated residential areas and their surroundings to find where high-level doses were likely to be detected for lowering the risk of exposure among residents.When little information was available, the investigations were implemented and the results contributed to both administrative policies and civil life.

Vegetation recovery of gypsum quarries: short‐term sowing response to different soil treatments

AbstractQuestionHow does the sowing of native species under different soil treatments contribute to the recovery of gypsum habitats affected by quarrying in Mediterranean environments?LocationMediterranean gypsum outcrops in Granada (SE Spain; 37º2′ N, 3º45′ W).MethodsWe conducted an experimental sowing of native perennial species from gypsum habitats (both gypsophiles and gypsovags) considering two factors: bedding materials and surface treatments. For bedding material we used: gypsum spoil, topsoil addition on gypsum spoil, raw gypsum and topsoil removal. The surface treatments were: control, sowing, sowing plus organic matter and sowing plus an organic blanket. There were five replicates per combination treatment (80 plots in total, of 25 m2 each). The sowing was performed in Nov 2009. All subplots were monitored to estimate density, richness, survival, growth of seedlings and herbaceous biomass, in two monitoring periods (Jul and Oct).ResultsNo gypsophiles or gypsovags were found in the control plots (no sowing or surface treatment), and therefore natural succession proved ineffective in the first year. In contrast, sowing was very satisfactory, especially on gypsum spoil, where mean density was of more than 15 individuals m−2. This result is noteworthy as this material remains after the end of gypsum mining activity. Spreading topsoil over gypsum spoil proved to be no more positive, since it provided not only seeds of target species but also of competitor species. Also, with regard to herbaceous species, this treatment produced a highly significant increase of biomass. The organic blanket increased plant density, whereas the addition of organic matter had significant positive effects on survival and growth of the seedlings. The global high survival rate is remarkable, especially for the gypsum spoil treatment.ConclusionsWe highlight the importance of implementing recovery measures in gypsum habitats. An appropriate selection of seed mixture and density, as well as the use of gypsum spoil (the most favourable bedding material, according the results), is sufficient to ensure presence of the key species. Both technical solutions tested, organic blanket installation and organic matter addition, improved the results in terms of density, survival and growth of the seedlings.

Ecological restoration on former agricultural soils: Feasibility of in situ phosphate fixation as an alternative to top soil removal

In Europe, high phosphorus (P) concentrations form the most important constraint on the ecological restoration of biodiverse vegetation on former agricultural soils, because they lead to dominance of highly competitive species like Juncus effusus or to algal blooms in flooded situations. Top soil removal is often not sufficient or not possible, so alternative methods have to be found. We therefore investigated whether modified bentonite clay to which 5% lanthanum had been added (LMC) and lime could effectively decrease bioavailable P and phosphate mobilization to the water layer in different soil types. A container experiment was performed using peaty and sandy soils with different Olsen-P concentrations, mixed with different doses of LMC and lime. The soils were exposed to two different common water regimes (moist and flooded). J. effusus seedlings were used as phytometers. Addition of LMC and lime lowered extractable P concentrations in some of the P-rich sandy soils. Only the highest LMC dose was able to decrease phosphate mobilization to the water layer in the sandy soils. However, neither LMC nor lime was sufficiently effective in reducing Olsen-P concentrations and J. effusus growth. Lime addition eventually even led to additional nutrient mobilization by alkalinization and increased mineralization of the soil. Our experiments therefore show that LMC and lime are not feasible alternatives to top soil removal, because they are inefficient in preventing dominance of highly competitive species under moist or shallowly flooded conditions. LMC may only be used to prevent phosphate mobilization to the water layer in deeply flooded situations, which may allow for a more biodiverse vegetation development.

Enhancement of late successional plants on ex-arable land by soil inoculations.

Restoration of species-rich grasslands on ex-arable land can help the conservation of biodiversity but faces three big challenges: absence of target plant propagules, high residual soil fertility and restoration of soil communities. Seed additions and top soil removal can solve some of these constraints, but restoring beneficial biotic soil conditions remains a challenge. Here we test the hypotheses that inoculation of soil from late secondary succession grasslands in arable receptor soil enhances performance of late successional plants, especially after top soil removal but pending on the added dose. To test this we grew mixtures of late successional plants in arable top (organic) soil or in underlying mineral soil mixed with donor soil in small or large proportions. Donor soils were collected from different grasslands that had been under restoration for 5 to 41 years, or from semi-natural grassland that has not been used intensively. Donor soil addition, especially when collected from older restoration sites, increased plant community biomass without altering its evenness. In contrast, addition of soil from semi-natural grassland promoted plant community evenness, and hence its diversity, but reduced community biomass. Effects of donor soil additions were stronger in mineral than in organic soil and larger with bigger proportions added. The variation in plant community composition was explained best by the abundances of nematodes, ergosterol concentration and soil pH. We show that in controlled conditions inoculation of soil from secondary succession grassland into ex-arable land can strongly promote target plant species, and that the role of soil biota in promoting target plant species is greatest when added after top soil removal. Together our results point out that transplantation of later secondary succession soil can promote grassland restoration on ex-arable land.

A trait‐based analysis of the role of phosphorus vs. nitrogen enrichment in plant species loss across North‐west European grasslands

Summary1. Both nitrogen (N) and phosphorus (P) enrichment have been identified to drive plant species losses from nutrient‐poor semi‐natural grasslands. The relative contribution of N vs. P to species loss remains unclear, however.2. We investigated how soil N and P availability affect the occurrence of 61 grassland species across North‐western Europe. We selected 132 study sites, located in Great Britain, Belgium and France, along a soil fertility gradient based on variability in atmospheric N deposition and on nutrient input from adjacent agricultural land. To gain insight into the underlying ecological mechanisms of species loss, we examined the role of a suite of plant traits that may mediate a species’ response to increased N or P availability.3. Mixed logistic regression showed that the occurrence of 24 plant species (39·3%) was affected by soil nutrient availability. Of these species, 18 were negatively affected by increased P (29·5%) and five by increased N (8·2%). Regionally declining plant species were absent from both P‐rich and N‐rich grasslands. Higher susceptibility to elevated P was associated with stress tolerance, low maximum canopy height and symbiosis with arbuscular mycorrhizae.4. Synthesis and applications. Although we also identified negative effects on plant diversity through N enrichment, our results strongly suggest that P enrichment is a more important driver of species loss from semi‐natural grasslands. Species in symbiosis with mycorrhizae and with low canopy height are especially at risk. Because detrimental effects of P enrichment are very difficult to mitigate due to the persistence of P in the soil, nature management should give absolute priority to preventing P input in grasslands through fertilization, agricultural run‐off or inundation with P‐polluted surface water. To restore species‐rich grasslands on P‐enriched soils, top soil removal appears crucial and more research regarding alternative removal strategies is essential.

Long-term effects of topsoil removal on soil productivity factors, wheat yield and protein content

Quantifying long-term effects of soil erosion on plant production and soil quality can aid in restoring degraded soils. The objectives of this study were to determine the long-term effects of topsoil removal on spring wheat (Triticum aestivum L.) yield and soil productivity factors. In 1982, the surface 0, 6, 12, and 18 cm of topsoil was mechanically removed from a Williams loam (fine-loamy, mixed, superactive, frigid Typic Argiustoll) and subsequently cropped. Soil samples were collected in 1998. There was no difference in soil organic matter (SOM), particulate organic matter (POM), mineralizable N, or water stable soil aggregates (WSA) in the surface 15 cm. Though not significant, there was an average increase of 1.2 g SOM kg−1 soil from the surface 15 cm since 1982, but fungal and bacterial biomass was reduced. The SOM and POM increased in the surface 15 cm of soil where grass was planted in strips between plots. Topsoil removal did not affect soil water at planting nor wheat yields from 1998–2001. The use of commercial fertilizer maintained crop yields, but SOM remained unchanged indicating that, restoring erosion damage is unlikely with a conventionally tilled wheat-fallow rotation in semi-arid regions.

Long-term heathland restoration on former grassland: The results of a 17-year experiment

European lowland heaths have declined by up to 80% due to land use change and lack of management. There has been considerable research into the restoration of this threatened habitat. However, long-term outcomes of restoration are poorly understood, especially in situations where past agricultural land use imposes severe constraints on community re-assembly. In 1989 a large-scale experiment was established to examine the effectiveness of five treatments to restore heathland on formerly productive grassland: (i) natural regeneration; (ii) herbicide application to facilitate regeneration; (iii) cultivation and application of seed-rich heathland vegetation; (iv) soil removal and incorporation of heathland topsoil; and (v) heathland translocation. After 17 years the pH of the unamended agricultural soil remained significantly higher than that of the adjacent heathland. All treatments showed different trajectories of vegetation change in the long-term. Natural colonisation by heathland species was slow due to seed limitation, resulting in formation of an acid grassland community. Heathland community assembly was not facilitated by destruction of the initial grassland with herbicide. Incorporation of topsoil had an intermediate effect on pH reduction. This may explain the subsequent failure of the plant community to assemble in the anticipated proportions, and the dominance of leguminous scrub species ( Ulex spp.). Turf translocation was effective in reducing pH to the required range and restoring the heathland community in the long-term. However, this technique should only be considered as a means of ‘rescue’ when habitat destruction is otherwise unavoidable. The only practical and sustainable means of increasing heathland extent on former farmland is the application of seed-bearing vegetation cut as part of routine management. However, this technique needs refining in order to establish the full range of characteristic heathland species.

Grassland restoration on former croplands in Europe: an assessment of applicability of techniques and costs

Grasslands used to be vital landscape elements throughout Europe. Nowadays, the area of grasslands is dramatically reduced, especially in industrial countries. Grassland restoration is widely applied to increase the naturalness of the landscape and preserve biodiversity. We reviewed the most frequently used restoration techniques (spontaneous succession, sowing seed mixtures, transfer of plant material, topsoil removal and transfer) and techniques used to improve species richness (planting, grazing and mowing) to recover natural-like grasslands from ex-arable lands. We focus on the usefulness of methods in restoring biodiversity, their practical feasibility and costs. We conclude that the success of each technique depends on the site conditions, history, availability of propagules and/or donor sites, and on the budget and time available for restoration. Spontaneous succession can be an option for restoration when no rapid result is expected, and is likely to lead to the target in areas with high availability of propagules. Sowing low-diversity seed mixtures is recommended when we aim at to create basic grassland vegetation in large areas and/or in a short time. The compilation of high-diversity seed mixtures for large sites is rather difficult and expensive; thus, it may be applied rather on smaller areas. We recommend combining the two kinds of seed sowing methods by sowing low-diversity mixtures in a large area and high-diversity mixtures in small blocks to create species-rich source patches for the spontaneous colonization of nearby areas. When proper local hay sources are available, the restoration with plant material transfer can be a fast and effective method for restoration.

Effects of evapotranspiration partitioning, plant water stress response and topsoil removal on the soil moisture regime of a floodplain wetland: implications for restoration

AbstractUnderstanding how the soil moisture regime changes following hydrological restoration activities in wetlands is essential for managers interested in establishing targeted wetland vegetation species. Based on observations from two floodplain sites in southwestern Wisconsin, a variably saturated hydrological model was developed and used to illustrate the importance of changing evapotranspiration (ET) partitioning [through changes in leaf‐area index (LAI)], the plant water stress function, and the thickness of a surficial silt‐loam alluvial deposit on the soil moisture regime. Floodplain restoration activities at these sites consisted of removing a layer of post‐settlement alluvium, which is a part of this deposit. Field observations following restoration of the pre‐settlement floodplain surface at one of the sites show a drier soil moisture regime at 10 and 25 cm depths at the restored (RES) site than at the unrestored site even though the potentiometric surface in a shallow monitoring piezometer was closer to the surface at the RES site. Simulations show that four factors may have contributed to this observation of relatively drier soils at the RES site: (1) lower LAI increases soil evaporation, (2) anaerobiosis limits transpiration near saturation, (3) a confining unit inhibits upward flow of water, and (4) removal of a 0·5‐m silt‐loam layer decreases the reservoir of soil moisture available to plant roots. Our work suggests the importance of effectively characterizing parameters that affect ET partitioning (i.e. LAI), determining the appropriate plant water stress function, and considering the effect of floodplain deposits that act as confining units when simulating the hydrology of floodplain wetland ecosystems. Copyright © 2010 John Wiley & Sons, Ltd.

Effects of granivorous rodents on direct seeding of oak and beech in relation to site preparation and sowing date

Planting bare-rooted seedlings is a rather expensive method to regenerate oak ( Quercus robur) and beech ( Fagus sylvatica). Direct seeding could reduce artificial regeneration costs substantially, but the method currently suffers from a number of problems, one of which is seed consumption by rodents. In the present study clear-cut areas in southern Sweden were prepared using one of four different mechanical site preparation methods – disc trenching, patch scarification, topsoil removal or mounding – then manually sown with acorns and beech nuts. Acorns were sown in May and July 2006, and both acorns and beech nuts were sown in May 2007. Three years following sowing, best seedling establishment from viable acorns, 60–70%, was achieved after sowing in mounds in May, and the subsequent survival reached 90–100%. After the first growing season for beech, both seedling establishment and subsequent survival was lower than for oak, which coincides with a higher number of lost beech nuts at the excavation to investigate the fate of seeds. Granivorous rodents ( Apodemus flavicollis, A. sylvaticus, Mus musculus, and Myodes glareolus) were live-trapped more frequently in the vicinity of slash piles compared to other micro-site features, such as uprooted stumps, snags and stones. In 2006, no connection was found between number of rodents captured and proportion of lost seeds, while in 2007 the two were in good accordance. No clear relationship was found between number of captured rodents, vegetation cover class and mechanical site preparation method. More rodents were captured in 2007 than in 2006, and there was an increase in captures from spring until late summer/autumn for both years, which was mirrored in the seedling establishment result from the three different times of sowing. Based on experiences from the present study the recommendation for successful direct seeding of oak on clear-cuts is a combination of mounding site preparation, removal of slash and sowing in May rather than July. However, the results indicate that successful direct seeding of beech is more difficult to achieve.

Species introduction in restoration projects – Evaluation of different techniques for the establishment of semi-natural grasslands in Central and Northwestern Europe

Abstract During recent decades, many studies have shown that the successful restoration of species-rich grasslands is often seed-limited because of depleted seed banks and limited seed dispersal in modern fragmented landscapes. In Europe, commercial seed mixtures, which are widely used for restoration measures, mostly consist of species and varieties of non-local provenance. The regional biodiversity of a given landscape, however, can be preserved only when seeds or plants of local provenance are used in restoration projects. Furthermore, the transfer of suitable target species of local provenance can strongly enhance restoration success. We review and evaluate the success of currently used near-natural methods for the introduction of target plant species (e.g. seeding of site-specific seed mixtures, transfer of fresh seed-containing hay, vacuum harvesting, transfer of turves or seed-containing soil) on restoration sites, ranging from dry and mesic meadows to floodplain grasslands and fens. Own data combined with literature findings show species establishment rates during the initial phase as well as the persistence of target species during long-term vegetation development on restoration sites. In conclusion, our review indicates that seed limitation can be overcome successfully by most of the reviewed measures for species introduction. The establishment of species-rich grasslands is most successful when seeds, seed-containing plant material or soil are spread on bare soil of ex-arable fields after tilling or topsoil removal, or on raw soils, e.g. in mined areas. In species-poor grasslands without soil disturbance and on older ex-arable fields with dense weed vegetation, final transfer rates were the lowest. For future restoration projects, suitable measures have to be chosen carefully from case to case as they differ considerably in costs and logistic effort. Long-term prospects for restored grassland are especially good when management can be incorporated in agricultural systems.

Prospects for fen meadow restoration on severely degraded fens

The majority of fens in Europe have been transformed for agricultural purposes and have disappeared or become degraded. Fen meadows that developed under low-intensity management of fens also have become degraded. In this paper, we consider the available restoration methods, biotic constraints for restoration and new prospects and approaches for the restoration of severely degraded fens. Due to irreversible changes in landscape settings, hydrology, soil and trophic conditions, a full restoration to natural mires is unlikely. Yet, an improvement of the ecosystem functions and revival of biodiversity in degraded fens is possible. A restoration of semi-natural meadows is one of the alternative targets. Important for restoration efforts to succeed are a sufficient reduction of nutrient levels and preventing acidification. In general, a combination of topsoil removal and seed transfer is an effective measure for fen meadow restoration, provided that groundwater seepage can be re-established. There are also several biotic limitations to fen meadow restoration, due to limited propagule availability of target species and the legacy of the former vegetation in form of its soil seed bank and high seed production by unwanted species. Under the present environmental conditions, the re-development of fen meadows on degraded fens will result in species compositions different from those observed in the past and such restoration may require considerable time and effort.

Importance of Seed and Microsite Limitation: Native Wildflower Establishment in Non-native Pasture

Barriers to establishing native plant communities on former pasture include dominance by a single planted species, hydrologic and edaphic alteration, and native species propagule limitation. Establishment may be dispersal-limited (propagules do not arrive at the site), microsite-limited (areas suitable for seedling emergence and survival do not exist), or both. Successful restoration strategies hinge on identifying and addressing critical limitations. We examined seed and microsite limitation to establishment of a native wildflower (Coreopsis lanceolata ) in a former pasture dominated by Paspalum notatum (bahiagrass). We determined the relative and interactive effects of microsite (irrigation and disturbance) and seed limitation on C. lanceolata establishment. We tested (1) irrigation (none, pre-seeding, and pre- and post-seeding), (2) disturbance (none, sethoxydim, glyphosate, and topsoil removal), and (3) C. lanceolata seeding rate (three seeding densities). Applying glyphosate before seeding increased C. lanceolata establishment compared to other disturbance treatments. Ultimately, C. lanceolata establishment was not affected by irrigation. Coreopsis lanceolata establishment was limited when seeded at 100 live seeds/m2 but not at 600 or 1100 live seeds/m2. Seed and microsite availability interactively affected C. lanceolata establishment, in that microsite limitation was biologically relevant only when a minimum number of seeds were present. In practice, both seed and microsite requirements must be met for successful establishment, and increasing the availability of seeds or microsites does not compensate for limitations of the other. Here, it is the relative importance of seed and microsite limitations that drives plant establishment; these limitations do not represent a simple dichotomy.

Immobilizing nitrogen to control plant invasion

Increased soil N availability may often facilitate plant invasions. Therefore, lowering N availability might reduce these invasions and favor desired species. Here, we review the potential efficacy of several commonly proposed management approaches for lowering N availability to control invasion, including soil C addition, burning, grazing, topsoil removal, and biomass removal, as well as a less frequently proposed management approach for lowering N availability, establishment of plant species adapted to low N availability. We conclude that many of these approaches may be promising for lowering N availability by stimulating N immobilization, even though most are generally ineffective for removing N from ecosystems (excepting topsoil removal). C addition and topsoil removal are the most reliable approaches for lowering N availability, and often favor desired species over invasive species, but are too expensive or destructive, respectively, for most management applications. Less intensive approaches, such as establishing low-N plant species, burning, grazing and biomass removal, are less expensive than C addition and may lower N availability if they favor plant species that are adapted to low N availability, produce high C:N tissue, and thus stimulate N immobilization. Regardless of the method used, lowering N availability sufficiently to reduce invasion will be difficult, particularly in sites with high atmospheric N deposition or agricultural runoff. Therefore, where feasible, the disturbances that result in high N availability should be limited in order to reduce invasions by nitrophilic weeds.