Underlying Mineral Soil Research Articles

Experimental Acidification Causes Soil Base‐Cation Depletion at the Bear Brook Watershed in Maine

There is concern that changes in atmospheric deposition, climate, or land use have altered the biogeochemistry of forests causing soil base‐cation depletion, particularly Ca. The Bear Brook Watershed in Maine (BBWM) is a paired watershed experiment with one watershed subjected to elevated N and S deposition through bimonthly additions of (NH4)2SO4 Quantitative soil excavations in 1998 measured soil pools of exchangeable base cations 9 yr after treatments began. Stream sampling at the weirs on a weekly and event basis, and weekly precipitation sampling, were used for input‐output estimates. The treated watershed had lower concentrations of exchangeable Ca and Mg in all horizons, with evidence for the greater depletion in the O horizon compared to underlying mineral soils, and in softwoods compared to hardwoods. This difference between watersheds is interpreted to be treatment‐induced base‐cation depletion, which was reinforced by model simulations. The difference between watersheds was 66 and 27 kg ha−1 of exchangeable Ca and Mg, respectively, after accounting for soil mass differences between watersheds. This was comparable with the total cumulative excess stream Ca and Mg export in West Bear after 9 yr of treatment of 55 and 11 kg ha−1, respectively. Model simulations of watershed response to treatments predicted excess soil exchangeable Ca and Mg losses in the treated watershed of 47 and 9 kg ha−1, respectively. These results indicate that the response to a step‐increase in N and S deposition during the first decade of treatments in this experimental forested watershed was to invoke cation‐exchange buffering, resulting in a net decline in soil exchangeable base cations.

Tree rings as Pb pollution archives? A comparison of 206Pb/ 207Pb isotope ratios in pine and other environmental media

Tree rings, if validated as an environmental archive for pollution, would provide a convenient, geographically widespread archive for studying the temporal and spatial distribution of atmospheric pollutants. We collected tree-ring records from Scots pine ( Pinus sylvestris L.), ranging in age from 100 to 300 years and from one spruce ( Picea abies), from sites in southern and northern Sweden and analyzed their stable lead isotopic composition ( 206Pb/ 207Pb). These results are compared to the Pb isotopic composition in soil profiles from each of the sites and temporal changes in the 206Pb/ 207Pb ratio in peat and lake sediment deposits in Sweden. The mineral soils at each site are characterized by high 206Pb/ 207Pb ratios (>1.35), while the ratios in the mor layer are low (1.14–1.16) and characterized by atmospheric lead pollution. The 206Pb/ 207Pb ratios of the tree rings, typically approximately 1.18–1.20, indicate a significant (10–30%) contribution of Pb derived from the underlying mineral soil. While peat and lake sediment records show that the 206Pb/ 207Pb ratio of atmospheric deposition has varied over time, with a pronounced trough between approximately 1930 and 1990, the tree rings show no similar trend. Further comparison of published Pb isotope data from other tree-ring records with time series from peat bogs and herbarium samples also shows poor agreement, and indicates that tree rings always contain a mixture of pollution Pb and Pb from the underlying mineral soil. The majority of Pb in the wood is derived from atmospheric pollution either directly, through aerial interception, or indirectly, through uptake from the large pool of accumulated pollution Pb in the soil. Since the Pb isotope ratios of the wood indicate that some natural Pb is taken up into the tree, then it must also be concluded that some fraction of the pollution Pb in the wood is likewise taken up from the forest soil. Based on the Pb isotope analyses, we can only conclude that dendrochemical records are not useful in temporal studies of metal pollution.

Characteristics of dissolved organic matter and phenolic compounds in forest soils under silver birch (Betula pendula), Norway spruce (Picea abies) and Scots pine (Pinus sylvestris)

SummaryThe aim was to characterize dissolved organic matter in soils under different tree species. Molecular size distribution and chemical composition of dissolved organic carbon and nitrogen were determined in water extracts from humus layers and mineral soils taken from silver birch (Betula pendula Roth.), Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.) stands. Concentrations of tannins and 15 phenolic acids in the humus layers were measured. Per unit of organic matter, the concentrations of dissolved organic C and N were larger in birch and spruce humus layers than in the pine humus layer. In the underlying mineral soil, the concentrations of dissolved organic C were similar at all sites, but the concentration of dissolved organic N was greater in spruce and pine soils than in birch soil. In all soils, the 10–100 kDa fraction was the most abundant molecular size group and hydrophobic acids the most abundant chemical group of dissolved organic C. In all humus layers, hydrophobic acids and hydrophilic bases were the major components of dissolved organic N. There were only minor differences in the concentrations of total tannins in the humus layers under different tree species. Small‐molecule tannins (about < 0.5 kDa) were most abundant in the birch humus, and large‐molecule tannins in the pine humus. Coniferous humus contained more ferulic and p‐coumaric acids than did the birch humus. The concentrations of 3,4 and 3,5‐dihydroxybenzoic acid, vanillic acid and 4‐hydroxybenzoic acid were similar in all soils.

Heuristic numerical and analytical models of the hydrologic controls over vertical solute transport in a domed peat bog, Jura Mountains, Switzerland

AbstractWe report the results of numerical and analytical simulations to test the hypothesis that downward vertical flow of porewater from the crests of domed alpine and kettle bogs controls vertical porewater distributions of major solutes such as Ca and Mg. The domed Etang de la Gruère bog (EGr), Switzerland, characterized by a vertical downward gradient of 0·04 and stratified layers of peat, is chosen as a field site for the model calibration and evaluation. The middle 4‐m section of the 6·5 m thick bog peat is heavily humified and has a hydraulic conductivity of ∼10−5·6 cm s−1. Above and below, peat is less humified with a hydraulic conductivity of ∼10−3 cm s−1. Heuristic finite difference simulations, using Visual MODFLOW, of the bog hydraulics show that the higher conductivity peat at the bog base is critical to create the observed deep, local flow cells that substantively recharge porewater.Model results and Peclet number calculations show that before ∼7000 14C yr BP diffusion of solutes from underlying mineral soils controlled the vertical distribution of porewater chemistry. From 7000 to ∼1250 14C BP the porewater chemistry was probably controlled by both upward diffusion and downward advection, and after ∼1250 14C yr BP porewater chemistry was probably controlled by downward advection. Concentrations of conservative major solutes in the porewaters of alpine, ombrotrophic bogs are the net effect of both downward vertical porewater movement and upward vertical diffusion, the magnitudes of which are delicately poised to the configuration of the bog water table over time and subsurface peat stratigraphy. Copyright © 2002 John Wiley & Sons, Ltd.

Simulating dispersive mixing in large peatlands

Numerical simulations indicate that mechanical dispersive mixing can be the dominant mass transport mechanism in large peatlands. Dispersive mixing driven by lateral flow can drive solute fluxes from the mineral soil upward to the peat surface and thereby explain observed patterns of bog and fen in large peatlands. Longitudinal and transverse dispersivities of only 0.5 and 0.05 m, respectively, were sufficient to supply solutes to the peat surface in the absence of upward ground-water flow. Incorporation of hydrodynamic dispersion in peatland systems explains apparent contradictions in solute migration in peatlands, allowing the simultaneous downward flux of labile carbon (i.e. root exudates) produced at the peat surface and upward migration of inorganic solutes from the underlying mineral soil. Previous models of peatland hydrogeochemistry that rely on advection alone as the dominant process for solute transport may therefore be inadequate to explain fully the hydrology, geochemistry, and evolution of large peatlands.

Seasonal variations in the chemical composition of dissolved organic matter in organic forest floor layer leachates of old-growth Scots pine (Pinus sylvestris L.) and European beech (Fagus sylvatica L.) stands in northeastern Bavaria, Germany

Organic matter dissolved in thepercolation water of forest soils contributeslargely to element cycling and transport ofnatural and anthropogenic compounds. The wayand extent to which these processes areaffected depends on the amount and the chemicalcomposition of soluble organic matter. Becausethe amount of soluble organic matter variesseasonally with changes in the microbialactivity in soil, it seems reasonable to assumethat there may be also seasonal changes in thechemical composition of dissolved organicmatter. We examined dissolved organic matter inthe seepage waters of organic forest floorlayers over a 27-month period (1997–1999) intwo forest ecosystems, a 160-year-old Scotspine (Pinus sylvestris L.) stand and a90-year-old European beech (Fagussylvatica L.) forest. The forest floorleachates were analysed for bulk dissolvedorganic C, C in hydrophilic and hydrophobicdissolved organic matter fractions,lignin-derived phenols (CuO oxidation),hydrolysable neutral carbohydrates and uronicacids, hydrolysable amino sugars, and stablecarbon isotope composition. In addition, westudied the samples by use of liquid-state13C-nuclear magnetic resonance (NMR)spectroscopy. For both investigated forest sites we foundthat the dissolved organic carbonconcentrations in forest floor leachates werelargest during summer. They peaked after rainstorms following short dry periods (106–145 mgdissolved organic C l−1). The proportionsof C in the hydrophilic fractions were largestin winter and spring whereas in summer andautumn more C was found in the hydrophobicfraction. According to liquid-state 13C-NMR spectroscopy, summer and autumn samples hadlarger abundances of aromatic and aliphaticstructures as well as larger proportions ofcarboxyl groups whereas the winter and springsamples were dominated by resonances indicatingcarbohydrates. Wet-chemical analyses confirmedthese results. Winter and spring samples wererich in neutral carbohydrates and amino sugars.The summer and autumn samples contained morelignin-derived phenols which were also strongeroxidised than those in the winter and springsamples. Seasonal changes of δ13C valueswere found to reflect the changes in thechemical composition of dissolved organicmatter. Most negative values occurred whenisotopically light lignin-derived compoundswere abundant and less negative values whencarbohydrates predominated. The different vegetation, age of thestands, and underlying mineral soils resultedin different concentrations of dissolvedorganic carbon and in differences in thedistribution between hydrophobic andhydrophilic organic carbon. Despite of this,the results suggest that the trends in temporalvariations in the composition of dissolvedorganic matter in forest floor seepage waterwere remarkably similar for both sites.Dissolved organic matter in winter and springseems to be mainly controlled by leaching offresh disrupted biomass debris with a largecontribution of bacterial and fungal-derivedcarbohydrates and amino sugars. Dissolvedorganic matter leached from the forest floor insummer and autumn is controlled by thedecomposition processes in the forest floorresulting in the production of stronglyoxidised, water-soluble aromatic and aliphaticcompounds. The chemical composition ofdissolved organic matter in forest floorseepage water in winter and spring indicateslarger mobility, larger biodegradability, andless interaction with metals and organicpollutants than that released during summer andautumn. Thus, the impact of dissolved organicmatter on transport processes may varythroughout the year due to changes in itscomposition.

Comparative fate of glyphosate and triclopyr herbicides in the forest floor and mineral soil of an Acadian forest regeneration site

Following applications of three different salt formulations of glyphosate (Vision®, Touchdown®, and Mon14420) and an ester formulation of triclopyr (Release®) to an Acadian forest regeneration site in New Brunswick, Canada, the fate and persistence of herbicide residues in the forest floor and underlying mineral soil were investigated. Within 14 days of treatment, maximal residue levels (average 8.3 µg·g dry mass–1) were observed in the forest floor matrix following application of the glyphosate formulations, with higher values (45.7 µg·g dry mass–1) observed for triclopyr. Residue maxima in the underlying mineral soil were, on average, 5.7-fold lower than those in the forest floor. In both matrices, glyphosate residues declined exponentially with time, irrespective of the formulation applied. Among the glyphosate treatments no significant differences (p = 0.16, p = 0.97, for forest floor and mineral soil respectively) were observed in the estimated times to 50% dissipation (DT50). Overall, average DT50 values for glyphosate were estimated as 12 ± 2 and 10 ± 3 days for the forest floor matrix and mineral soil, respectively. Triclopyr residues, particularly in the forest floor, were characterized by a series of transient increases, possibly reflecting temporally varying inputs from dew, rainwash, or litter fall from surrounding treated vegetation. Triclopyr residues also dissipated with time, with approximate DT50 values ranging from 39 to 69 days in the forest floor and mineral soil, respectively.

Effect of human activities on forest ecosystems: N cycle and soil fertility

Forests are important terrestrial ecosystems, with particular nutrient cycling mechanisms to maintain structure and functions. Nitrogen is essential for forest growth and development, and commonly limited for the forest productivity. N cycles in forest ecosystems are frequently disturbed by intensive human activities. Based on a variety of research results, some potentially important human disturbances are discussed and their effects on forest ecosystems are reviewed. Precipitation is a considerable N input to forest ecosystems. However acid precipitation is detrimental to the ecosystems in the long run. Acidification causes remarkable reduction in forest productivity in the world, due to the harmful effect of acid on plant physiology and more importantly to the reduction in soil fertility by lowering mineralization and increasing N loss by runoff and leaching. The most important nutrient cycling mechanism in forest ecosystems is litterfall. Removal of trunks only for commercial use will not affect N cycle in forest ecosystems significantly, but attention on the intensity and rotation times of harvest should be paid. Clear-cutting should be prevented in forest harvesting. It deserves more attention that the change of environment after clear-cutting will affect the N cycling processes in forest ecosystems, which substantially influence soil fertility and forest productivity. Ammonification and nitrification processes are stimulated after harvesting, by which N is becoming more moveable. Unfortunately in the situation of no assimilation after clear-cutting, much of N will be lost out of the ecosystems and soil fertility will be diminished. The N pool in forest floor and underlying mineral soil is big, but forest productivity is generally low in natural conditions. Forest management is needed to meet the increasing demand for forest products. Optimization of stands structure is the most economic way to increase soil fertility and forest productivity. Mixed coniferous-broad leaved forest is recommended for plantation practice. Addition of fertilizer N effectively promotes forest productivity and may compensate for the N loss from the systems by harvesting.

Rapid accumulation and turnover of soil carbon in a re-establishing forest

Present understanding of the global carbon cycle is limited by uncertainty over soil-carbon dynamics. The clearing of the world's forests, mainly for agricultural uses, releases large amounts of carbon to the atmosphere (up to 2 x 1015 gyr-1), much of which arises from the cultivation driving an accelerated decomposition of soil organic matter. Although the effects of cultivation on soil carbon are well studied, studies of soil-carbon recovery after cultivation are limited. Here we present a four-decade-long field study of carbon accumulation by pine ecosystems established on previously cultivated soils in South Carolina, USA. Newly accumulated carbon is tracked by its distinctive 14C signature, acquired around the onset of forest growth from thermonuclear bomb testing that nearly doubled atmospheric 14CO2 in the 1960s. Field data combined with model simulations indicate that the young aggrading forest rapidly incorporated bomb radiocarbon into the forest floor and the upper 60 cm of underlying mineral soil. By the 1990s, however, carbon accumulated only in forest biomass, forest floor, and the upper 7.5 cm of the mineral soil. Although the forest was a strong carbon sink, trees accounted for about 80%, the forest floor 20%, and mineral soil <1%, of the carbon accretion. Despite high carbon inputs to the mineral soil, carbon sequestration was limited by rapid decomposition, facilitated by the coarse soil texture and low-activity clay mineralogy.

Controls on N Retention and Exports in a Forested Watershed

We conducted a 15N-tracer study in a fertilized, forested catchment at the Bear Brook Watersheds in Maine (BBWM), USA, in order to characterize N cycling processes, identify sinks for ammonium-N additions, and determine the contribution of the experimental ammonium additions to nitrate exports from the treated catchment. Distributions of 15N in plant tissues, soils, precipitation and streamwater collected before adding tracers showed that nitrate-N (the dominant form of inorganic N deposition at the site) inputs under ambient conditions were depleted in 15N relative to plants and that soil was enriched in 15N relative to plants. The 15N content of streamwater nitrate was within the range of 15N contents in natural plant tissues, suggesting that nitrate deposited from the atmosphere is reduced and assimilated into soil and plant N pools before being leached as nitrate from the catchment. Variations in 15N natural abundances also suggested that most N uptake by trees is from the forest floor and that nitrification occurs in soils at this catchment under ambient conditions. Changes in 15N contents of plant tissues, soils and streamwater after adding a 15N tracer to the ammonium sulfate fertilizer applied to the treated catchment showed that soils were the dominant sink for the labeled ammonium. Surface soils (Oca horizon plus any underlying mineral soil to 5cm depth) assimilated 19 to 31 percent of the 42 kg ha-1 of 15N-labelled ammonium-N during the tracer study. Aboveground biomass assimilated 8 to 17 percent of the labeled ammonium-N additions. Of the three forest types on the catchment, the soil:biomass assimilation ratio of labeled-N was highest in the spruce forest, intermediate in the beech-dominated hardwood forest and lowest in the mixed hardwood-spruce forest. Although ammonium sulfate additions led to increases in streamwater nitrate, only 2 of the 13 kg ha-1 of nitrate-N exported from the catchment during the 2 years of tracer additions was derived from the 42 kg ha-1 of labeled ammonium-N additions.

Copper and nickel mobility in podzolic forest soils subjected to heavy metal and sulphur deposition in Western Finland

The distribution of copper and nickel down the soil profile has been investigated at 4 plots along a heavy metal and sulphur gradient extending for a distance of up to 8 km from a copper smelter in Western Finland. Emissions from the smelter have earlier been at a relatively high level, but were considerably reduced at the beginning of the 1990's prior to the start of the experiment. Soil samples were taken in 1991, and soil water quality has been monitored using zero-tension lysimeters (5, 20 and 40 cm depth) during the growing season in 1992–1994. The organic layer and mineral soil on the plot nearest to the smelter contains considerable amounts of Cu and Ni. The Cu/Ni ratio in the organic layer was much higher than that in the underlying mineral soil, indicating that Cu is more strongly adsorbed in the organic layer than Ni. Copper concentrations in percolation water showed a peak at 20 cm depth, while for Ni the concentrations at 40 cm were higher than those at 5 cm. The lower Cu and Ni concentrations at 5 cm depth could be signs of a gradual detoxification of the surface, i.e. the gradual leaching of the mobile Cu and Ni components down to greater depths.

The erodibility of upland soils and the design of preafforestation drainage networks in the United Kingdom

Hydraulic thresholds for erosion of fourteen upland mineral and organic soils were determined in a hydraulic flume. These soils are from areas to be afforested in the United Kingdom. Some of the group are erosion resistant but others are susceptible to erosion once denuded of vegetation; for example, by preafforestation ploughing. These threshold data were required to calibrate a hydraulic model for effective design of preafforestation drainage networks on a variety of soils. However, simple field measures of soil properties indicative of erosion potential would be of value to the forestry industry for management purposes. Consequently, hydraulic threshold data were related by linear regression methods to basic soil properties, including organic content, grain size, bulk density, compression strength and penetration resistance. The investigation concluded that four peat soils are not eroded by clear water velocities up to 5·7 m s−1, although a mineral bedload might induce erosion at lesser current speeds. Penetration resistance is a good field indicator of the degree of humification of the peat soils. Although selected physical parameters contribute resistance to water erosion, an increased organic content is pre-eminent in reducing erosion susceptibility in both organic and mineral soils. Although compressive strength was not indicative of soil erodibility, field measurements of penetration resistance on a variety of soils could be related to hydraulic thresholds of erosion; albeit through the construction of discriminant functions interpolated by eye. Consequently, organic content (laboratory) or penetration resistance (field) might form the basis of classifying upland soils in terms of erodibility. Mineral soils differ widely in terms of their erodibility, so that subject to further consideration, the use of ploughing for forestry cultivation might be appropriate in wider circumstances than presently recommended by the Forests and Water Guidelines. Ploughing should be acceptable on deep peat providing the underlying mineral soil is not exposed in the bottom of the furrow, and furrows are not led from mineral soils on to deep peat. © 1997 John Wiley & Sons, Ltd.

Trace Metal Geochemistry in Spodosols of the Northeastern United States

AbstractLong‐term or postglacial (≈ 12 000‐year) net fluxes of Pb, Cu, Zn, Ni, Cr, and Co through three Spodosols, formed from different parent materials, were calculated using mass‐balance modeling. Metal contents in vegetation and O horizons were also estimated and measured, respectively. Total metal contents in mineral horizons were fractionated into different operationally defined pedogenic phases using a sequential extraction technique. With few exceptions, the three soils had significant leaching losses for all trace metals (from 7–508 kg ha−1), the greatest losses generally occurring in the E and upper horizons. The magnitude of losses by leaching varied with parent material, as a result of differences in weatherabilities of mineral suites. Combined metal contents in vegetation and O horizons, which may originate from anthropogenic additions as well as mineral weathering, are significantly large in some cases; however, these metal amounts are apparently not large enough to offset long‐term leaching losses from the underlying mineral soil profiles. Some B and C horizons had net accumulations of extractable Pb, Cu, and/or Ni‐bearing phases. Based on the sequential extraction procedure used, the extractable metal forms are probably pedogenic Fe oxide‐ and/or organic‐bound phases. One soil apparently gained Cu (≈38 kg ha−1), which may have been from atmospheric deposition.

A litter-bag study of mite densities (Actinedida and Oribatida) in Atriplex litter and soil of a desert site in northern Chile

We tested the seasonal responses of soil mites, particularly Actinedida and Oribatida, in decomposing surface litter of three saltbush species, in the underlying mineral soil, and to the microhabitat conditions (litter and mineral soil together). The numerical changes were monitored in litter bags that enclosed 10 0 g of oven-dried leaf material collected from Atriplex repanda Phil., A. nummularia Lindl. and A. semibaccata R. Br. (Chenopodiaceae). These species have been widely utilized in land reclamation programs in north-central Chile. In terms of total numbers of mites, actinedids and oribatids, Atriplex repanda litter provided a better habitat than A. semibaccata and A. nummularia, an introduced Australian species. We detected seasonal patterns of density that were related to litter species and to soil conditions.

Redistribution of soil nitrogen, carbon and organic matter by mechanical disturbance during whole-tree harvesting in northern hardwoods

To investigate whether mechanical mixing during harvesting could account for losses observed from forest floor, we measured surface disturbance on a 22 ha watershed that was whole-tree harvested. Surface soil on each 10 cm interval along 81, randomly placed transects was classified immediately after harvesting as mineral or organic, and as undisturbed, depressed, rutted, mounded, scarified, or scalped (forest floor scraped away). We quantitatively sampled these surface categories to collect soil in which preharvest forest floor might reside after harvest. Mechanically mixed mineral and organic soil horizons were readily identified. Buried forest floor under mixed mineral soil occurred in 57% of mounds with mineral surface soil. Harvesting disturbed 65% of the watershed surface and removed forest floor from 25% of the area. Mechanically mixed soil under ruts with organic or mineral surface soil, and mounds with mineral surface soil contained organic carbon and nitrogen pools significantly greater than undisturbed forest floor. Mechanical mixing into underlying mineral soil could account for the loss of forest floor observed between the preharvest condition and the second growing season after whole-tree harvesting.

When It's Hot, It's Hot... Or Maybe It's Not! (Surface Flaming May Not Portend Extensive Soil Heating)

Fire effects on aplant community, soil, and air are not apparent when judged only by surface fire intensity. The fire severity or fire impact can be described by the temperatures reached within the forest floor and the duration of heating experienced in the vegetation, forest floor, and underlying mineral soil. Temporal distributions of temperatures illustrate heat flow in duff and mineral soil in three instrumented plots: two with slash fuel over moist duff and one with litter fuel over dry duff. Fires in the two slash fuel plots produced substantial flame lengths but minimal heating in the underlying mineral soil. In contrast, smoldering combustion in the dry duff plot produced long duration heating with nearly complete duff consumption and lethal temperatures at the mineral soil surface. Moisture content of duff and soil were key variables for determining f i e impact on the forest floor.

Aluminum‐Binding Ability of Soluble Organics in Douglas Fir Litter and Soil

AbstractOrganic matter from litter and soil are important metal‐mobilizing agents. This study was conducted to characterize the Al‐binding abilities of soluble organics from both Douglas fir litter and soil (fine‐loamy, mixed, mesic Ultic Haploxeralf). A modified ion‐pairing chromatographic technique was used to differentiate organics according to their Al‐binding abilities. Further identification with high‐performance liquid chromatography (HPLC) found gallic, catechol, salicylic, and phthalic as the most strongly Al‐binding ligands among the aromatic acids identified. Moderate binding ability was exhibited by 3,4‐dihydroxybenzoic acid; benzoic, vanillic and 4‐hydroxybenzoic acids were the least strongly binding. The identified aliphatic acids (shikimic, oxalic, succinic, fumaric, malic, and citric) were not differentiated, due to their weaker binding to Al and to the fractionation column. For the unidentified organics, suggestions are made on their functional structure that will be useful for more exhaustive studies. Greater amounts of Al‐binding ligands were found in litter than in soil. The effect of different litter types on Al solubilization in underlying mineral soils can be obtained by comparing their Al‐fractionation characteristics.

Alder carr, growth and drowning in the IJsselmeer region, an aspect of the Dutch coastal development

SUMMARY A peat layer and the underlying mineral soil in a section of the Zuidelijke Flevopolder in the central Netherlands has been studied for pollen analysis. The pollen spectra from the mineral soil reflect a Late-Atlantic forest development under relatively dry soil conditions. Podzolizing has started, but as a consequence of a rise of the groundwater table the soil became wetter and an alder carr could develop. A further rise of the water table is thought to be responsible for the decline of the alder carr after 3780 ± 60 bp. Eutrophic peat growth at site OZ-43 is synchronous with the deposits belonging to the ‘Cardium transgression’ phase. The development in the IJsselmeer region was strongly correlated with the coastal development of Noord-Holland. The oldest 'Cardium deposits' are thought to be transported via the Oer-IJ and the youngest via tidal channels in the north near Hoorn. The clay sediments covering the peat belong to the Zuiderzee deposits and indicate a hiatus between the peat and the clay deposits of at least 3500 calendar years.

Soil shear strength measurements and their relevance to windthrow in Sitka spruce

Abstract. The measurement of the shear strength of the root plate/soil interface beneath mature trees is described. Results from this method are given for a total of 77 sample trees from crops of Sitka spruce aged between 24 and 35 years growing on a peaty gley, a deep peat and a brown earth. Shear strength was much higher for the brown earth than for either the peaty gley or the deep peat, mainly because there was a less clear‐cut boundary to the rooting depth compared with the rooting boundary caused by the high water table on the peat sites. There was a slightly higher shear strength for the peaty gley than for the deep peat, but no apparent difference in shear strength between the peat and the underlying mineral soil in the peaty gley. The shear strength measurements were consistent with observed differences in tree stability and the method of measuring shear strength aids the assessment of susceptibility of trees to windthrow.

Nitrogen and Carbon accretion on Ohio coal minesoils: Influence of soil-forming factors

Plantations of white pine ( Pinus strobus L.), tuliptree ( Liriodendron tulipifera L.), white ash ( Fraxinus americana L.) and black locust ( Robinia pseudoacacia L.), established in 1946 on ungraded calcareous, neutral or acid coal spoils, were sampled in 1976 for weight, carbon and nitrogen content of the forest floor, and for total N concentration in 4 depth increments of the underlying mineral soil. Minesoil characteristics were related to the following soil-forming factors: parent material (overburden), organisms (tree species) and relief (aspect and slope position). Forest floor weight was high under white pine on all parent materials and under black locust on acid parent material. Nitrogen content of the forest floor was highest on acid minesoil, as was total weight of N in the forest floor under all species except tuliptree. Although concentration of N in the forest floor was highest under black locust, total weight of forest floor N under pine exceeded that under locust on calcareous and neutral minesoils because of the much greater weight of forest floor under pine. C/N ration of forest floor was lowest under locust and on the acid minesoil. Total N concentration was highest at all depths in soils that formed under black locust: rate of decrease in total N concentration between the 0–5 and 5–15 cm depth increments was also greatest under black locust. Soils formed on calcareous parent material had higher total N concentrations at all depths than those formed on neutral or acid parent materials. We estimate that concentration of total N in the 0–5 cm horizon of calcareous minesoils has increased from 0.04 to 0.23% in the 30 years since tree establishment. The corresponding increase in the acid minesoils has been from 0.03 to 0.18%. Our results show that accretion of carbon and nitrogen on minesoils will be influenced both by overburden strata placed at the surface as parent material of the new soil and by tree species chosen for planting.