Water and oxygen regimes under conifer plantations and native vegetation on upland peaty gley soil and deep peat soils

Concentrations of oxygen and carbon dioxide were measured in an upland peaty gley soil during two growing seasons and a deep peat during one season. Measurements were compared with the soil water regimes on both soils. Comparison was also made between planted areas of Sitka spruce and Lodgepole pine, and areas of the native vegetation (Molinia grassland on the peaty gley, and Calluna heath on the deep peat). In 13 m tall pure stands of the pine and spruce on the peaty gley soil about 28% of the rainfall was intercepted by the canopy and evaporated without reaching the soil, and the watertable was deeper and matric potentials were lower than under grass. When the matric potential fell below ?5 kPa in the upper soil layers, high oxygen concentrations prevailed. In undisturbed peat, waterlogged conditions produced an anaerobic regime virtually to the surface, but a 1 m deep drainage ditch lowered the watertable and created an aerobic regime within the top 0.3 m of peat. The presence of tree crops on drained plots increased the depth of drying during the summer months, and aerobic conditions reached 0.4 m depth under Sitka spruce and 0.5m under Lodgepole pine. On the peaty gley also, Lodgepole pine dried and aerated the soil to a greater depth than Sitka spruce during the summer, but no difference in water regime was evident in the winter.     

Water and oxygen regimes of four soil types at Newcastleton Forest, south Scotland

The water and oxygen status of four upland soils under Sitka spruce plantations was studied for 2 years. In a brown earth, waterlogging only occurred ephemerally in the subsoil and oxgen concentrations were generally high. In contrast, waterlogged and near-anaerobic conditions persisted for much of the year in stagnogley and stagnohumic gley soils. In a peaty stagnopodzol moist conditions occurred above and below the thin ironpan, but while high oxygen concentrations generally persisted in the subsoil, low concentrations were common in the soil above. In the brown earth, healthy roots of Sitka spruce were present at a depth of 85 cm, but in the gley soils rooting was mainly limited to 25 cm and many roots were dead. In the peaty stagnopodzol, roots penetrated the ironpan and grew in the subsoil to 75 cm depth.     

Estimation of wood density and chemical composition by means of diffuse reflectance mid-infrared Fourier transform (DRIFT-MIR) spectroscopy

Sitka spruce (Picea sitchensis) samples (491) from 50 different clones as well as 24 different tropical hardwoods and 20 Scots pine (Pinus sylvestris) samples were used to construct diffuse reflectance mid-infrared Fourier transform (DRIFT-MIR) based partial least squares (PLS) calibrations on lignin, cellulose, and wood resin contents and densities. Calibrations for density, lignin, and cellulose were established for all wood species combined into one data set as well as for the separate Sitka spruce data set. Relationships between wood resin and MIR data were constructed for the Sitka spruce data set as well as the combined Scots pine and Sitka spruce data sets. Calibrations containing only five wavenumbers instead of spectral ranges 4000-2800 and 1800-700 cm(-1) were also established. In addition, chemical factors contributing to wood density were studied. Chemical composition and density assessed from DRIFT-MIR calibrations had R2 and Q2 values in the ranges of 0.6-0.9 and 0.6-0.8, respectively. The PLS models gave residual mean squares error of prediction (RMSEP) values of 1.6-1.9, 2.8-3.7, and 0.4 for lignin, cellulose, and wood resin contents, respectively. Density test sets had RMSEP values ranging from 50 to 56. Reduced amount of wavenumbers can be utilized to predict the chemical composition and density of a wood, which should allow measurements of these properties using a hand-held device. MIR spectral data indicated that low-density samples had somewhat higher lignin contents than high-density samples. Correspondingly, high-density samples contained slightly more polysaccharides than low-density samples. This observation was consistent with the wet chemical data.     

Collar insertion depth effects on soil respiration in afforested peatlands

Using collars for measuring soil respiration and its component fluxes in closed chamber systems relies on two main assumptions. Firstly, it is assumed that shallow collars prevent lateral soil gas leakage beneath the chamber’s walls and the underestimation of soil CO₂ fluxes, and secondly, the insertion of deeper collars excises all living roots and the autotrophic flux is eliminated. It was hypothesised that previous findings on collar insertion impacts on autotrophic and total soil respiration also apply to afforested peatlands. In these ecosystems, a large fraction of fine roots grow close to the soil surface. Therefore, the use of shallow collars may sever some fine roots and hyphae of mycorrhizal fungi, and therefore, it may lead to underestimation of total soil respiration. It was also hypothesised that this underestimation may be greater than a possible CO₂ leakage from lateral diffusion of soil gas as a result of not using collars. In this study, we measured soil CO₂ efflux in a Sitka spruce and a lodgepole pine plantation on blanket peat in southern Ireland. A surface collar (not inserted into the ground) and six insertion depths (5, 10, 15, 25, 35 and 45 cm) were established to assess the effect of the collar insertion depth on autotrophic and total soil respiration. The insertion depth of 5 cm reduced total soil respiration by 47 and 32% in the spruce and pine stands, respectively. Using nonlinear equations, it was estimated that a frequently used shallow insertion of 1.5 cm would have reduced this efflux by 35 and 20% in each stand, respectively. Moreover, it was demonstrated that this reduction was greater than a possible lateral soil gas leakage. These results suggest that the insertion of shallow collars should be avoided and surface collars permanently anchored in the soil should be used instead.     

The variation of soil water regime, oxygen status and rooting pattern with soil type under Sitka spruce

Soil water regime, oxygen status and rooting pattern under Sitka spruce were characterized in five soil types: a waterlogged peaty gley, a peaty gley, a flushed peaty gley, a surface water gley and a brown forest soil during 1982. The waterlogged peaty gley had a high water-table which only dropped below 30 cm depth for 46 d during the summer. Below the water-table the profile was anoxic and rooting was restricted to a depth of 12cm. The peaty gley experienced seasonal waterlogging with a winter water-table around 15cm depth. Roots that grew further down the profile during the summer as the topsoil dried to –100 kPa matric potential were later killed when the water-table rose. The top 30 cm of the flushed peaty gley remained oxygenated even below the water-table. Roots survived below the winter water-table. The top 30 cm of the surface water gley and brown forest soil were freely draining and remained aerated throughout the year. The platinum electrode polarographic method demonstrated that there was a sharp transition to anoxic conditions just above the water-table at the first two sites.     

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 mineralization and water-table height in oligotrophic deep peat

Summary Peat cores, 0–60 cm depth, were taken on 14 occasions from three experimental plots where the water levels in the surrounding ditches had been artificially controlled for 14 years at 0, 20 and 50 cm below the surface. Numbers of aerobic and anaerobic ammonifying bacteria in the profile were significantly increased (P< 0.05) by lowering the water level from 0 to 50 cm. These increases occurred mainly in the surface 20 cm horizon, where 80%–90% of the ammonifying bacteria in the profile occurred. Mineral N in fresh samples, which was present almost entirely as ammonium, decreased sharply with depth below 20 cm, and on two occasions concentrations were significantly greater (P<0.05) in plots with water levels at 20 and 50 cm than in the flooded peat. Readily mineralized N, produced during waterlogged incubation at 30°C for 9 weeks, was significantly greater (P<0.05) on eight occasions in samples from plots with water levels at 20 or 50 cm than in those where the water level was at the surface. Calculations showed that the increases in N availability as a result of lowering the water-table could be attributed mainly to deeper rooting.     

Variation between mite communities in Irish forest types – Importance of bark and moss cover in canopy

Extensive afforestation took place in Ireland during the twentieth century and the forest cover currently represents about 10% of the land area. However, approximately 50% of this forest is Sitka spruce, a non-native species introduced from the North Western United States of America. Little is known about the microarthopods of these forests and the current study examined the mites (Oribatida and Gamasina) occurring in the canopy, moss (both on the soil surface and in the canopy) and soil of oak, ash, Scots pine and Sitka spruce forests in Ireland to compare the mite assemblages in each and to determine the associations between forest type and the form of constituent microhabitats in determining the structure of this fauna. There were significant differences between the diversity and species composition of the assemblages in the different forest types with the largest species richness occurring in oak forest and the smallest in first rotation Sitka spruce forest. Analysis of our data, together with the results from other studies, suggest that the differences arise because the variation between the architecture of the tree species is reflected in the structure of microhabitats such as the form of the bark and the extent of moss cover. Thus while the ultimate factors affecting the variation in the mite fauna may be the form of the microhabitats, these are intrinsic properties of the forests associated directly with the species of tree. Finally, our results do not support the view that exotic species will necessarily have low biodiversity of mites than native forests.     

Die Wirkung von ausgefaultem Klärschlamm auf den Stoffwechsel 3jähriger Fichten und Kiefern

Effect of digested sewage sludge on the metabolism of three year old spruce and pine trees. Three year old Norway spruce and Scots pine trees were grown in mixtures of sand and sewage sludge. The mixtures used were composed of 5 litres of sand and 1.25 or 1.67 litres of digested sewage sludges from municipal waste water treatment plants. A mixture of 5 litres of sand and 1.67 litres of peat was used as a control. In all cases sewage sludge depressed growth as measured by height and the yields of fresh material. The contents of N, Ca, Mg, Zn in the needle dry matter were higher than in control. The P content was only increased in the newly formed needles in the high sewage sludge treatments. However, the corresponding Mn contents were depressed, also the K contents in spruce. The higher rate of nitrogen assimilation, in the sewage sludge treatments especially in spruce, lead to a greater accumulation of the amino acid arginine and also to a reduction in the content of organic acids and polyphenols. These effects do not explain why some plants died. For spruce a lethal factor appears to be the depression of water uptake combined with high transpiration. The ratio of K/Ca in the needles was extremly low, which indicated a possibility of both potassium deficiency and calcium toxicity. The observed enrichment of proline is also associated with water stress. Scot pine was more sensitive than spruce to treatment with sewage sludge. In all treatments with sludge some Scot pine trees died, especially when municipal wastewater sewage sludge was used.     

Modification of soil structural and hydraulic properties after 50 years of imposed chaparral and pine vegetation

Although biotic communities have long been recognized as important factors in soil development, especially of A horizons, few studies have addressed their influence on soil physical properties in nonagricultural settings. A biosequence of 50-year-old soils supporting near monocultures of Coulter pine (Pinus coulteri), scrub oak (Quercus dumosa), and chamise (Adenostoma fasciculatum) was used to determine the relative influence of vegetation type and associated soil organisms on the development of soil structural characteristics and water flow. Total porosity ranged from a high of 51% in the heavily worm-worked A horizon under oak to a low of 39% within the 35- to 50-cm depth under pine, where earthworms were absent. Macroporosity (pores with diameters >300 μm) was highest in the A horizon under oak (15.6%) and lowest under pine (9.5%). Saturated hydraulic conductivity of surface soils ranged from 10.8 cm h⁻¹ under oak to 3.2 cm h⁻¹ under pine. Soil under chamise, which had fewer earthworms than that under oak, had K_sat and bulk density values intermediate between oak and pine. Root and macrofauna distributions suggest that roots are the dominant factor in the development of macroporosity under pine, while earthworms have had the greatest effect under oak. Porosity has increased at an average rate of 0.22% per year in the 0- to 7-cm depth under oak (from 41% to 56%), but has not been significantly altered within the same depth under pine. Below the 7-cm depth, porosity values are similar for each vegetation type and the original parent material. Available water capacity (AWC) within the first 0- to 7-cm depth has increased from the original values (about 0.11 m³ m⁻³) to 0.17 m³ m⁻³ under oak, 0.16 m³ m⁻³ under chamise, and 0.13 m³ m⁻³ under pine. The data show that the presence of burrowing macrofauna, which is determined by litter palatability and therefore indirectly controlled by vegetation, can significantly influence porosity, increasing the water-holding capacity of a soil.     

A drainage experiment on a peaty gley soil at Kershope Forest, Cumbria

Abstract. The effects of ditch spacing (10, 20 and 40 m) and depth (60 and 90 cm) on watertable depth were measured in a Sitka spruce plantation before and after drainage and finally after part of the plantation had been clearfelled. No significant differences in watertable depth were recorded between drainage treatments mainly because the ditch spacings were too large but also because of inadequate calibration of the site before the drainage treatments were applied. By the time of felling, the site had been thoroughly calibrated for the behaviour of the watertable, enabling sensitive comparisons to be made, and a significant rise in the watertable was recorded after felling.     

Laboratory experiments on drought and runoff in blanket peat

Global warming might change the hydrology of upland blanket peats in Britain. We have therefore studied in laboratory experiments the impact of drought on peat from the North Pennines of the UK. Runoff was dominated by surface and near‐surface flow; flow decreased rapidly with depth and differed from one type of cover to another. Infiltration depended on the intensity of rain, and runoff responded rapidly to rain, with around 50% of rainwater emerging as overland flow. Drought changed the structure of the peat and the subsequent behaviour of the peat in response to rain. Surface runoff was reduced, infiltration increased and flow increased within the deeper peat layers. Old and new water produced from the peat during simulated storms was identified by bromide tracing; the amount of old mobile water flushed out of the top few centimetres was small and there was less from deeper peat layers. No significant difference in the old and new water mixing processes could be identified between the control plots and the drought treatment plots. Lissamine staining showed preferential bypass flow through macropores in the peat, though only in the top 5 cm. Following drought, however, macroporosity increased within the upper peat layers, and preferential flow extended deeper than in controls. Peat structure recovered somewhat after drought, but the effects of the drought were long‐lasting. If these effects extend to the field during drier summers then we can expect changes to the hydrology and associated chemistry of blanket peat catchments in the British uplands.     

The effects of forest liming on fertilization on fine-root growth

Results are reported from the investigations of fine-root development in Norway spruce and Scots pine stands in South and Central Sweden, subjected to different liming and fertilization regimes. The growth responses of the fine roots to varying mineral nutrient regimes seem to be dependent on the tree species, the age of the tree population and soil conditions. Nitrogen fertilization in some of the investigated stands had negative effects on the development of fine roots, resulting in a reduction in the amount of fine roots to about 50% of that in the control. However, negative effects were not consistent in all stands, positive growth responses were also obtained. In these stands, the amount of fine roots was increased by 2 to 3 times. Liming in combination with fertilization resulted in a strong decrease in the amount of fine roots to about 30% of that in the control in some of the investigated stands. Liming in high doses is expected to produce a persistent increase in pH (H₂O and base saturation in the soil. However, results from the present study suggest that liming may have a negative effect on the development of tree fine roots, particularly in areas with a high N deposition. The application of crushed dolomite had less negative effects on fine root development than crushed calcitric lime and different types of residue products, such as wood and peat ashes.     

The effects of forest liming on fertilization on fine-root growth

Results are reported from the investigations of fine-root development in Norway spruce and Scots pine stands in South and Central Sweden, subjected to different liming and fertilization regimes. The growth responses of the fine roots to varying mineral nutrient regimes seem to be dependent on the tree species, the age of the tree population and soil conditions. Nitrogen fertilization in some of the investigated stands had negative effects on the development of fine roots, resulting in a reduction in the amount of fine roots to about 50% of that in the control. However, negative effects were not consistent in all stands, positive growth responses were also obtained. In these stands, the amount of fine roots was increased by 2 to 3 times. Liming in combination with fertilization resulted in a strong decrease in the amount of fine roots to about 30% of that in the control in some of the investigated stands. Liming in high doses is expected to produce a persistent increase in pH (H₂O) and base saturation in the soil. However, results from the present study suggest that liming may have a negative effect on the development of tree fine roots, particularly in areas with a high N deposition. The application of crushed dolomite had less negative effects on fine root development than crushed calcitric lime and different types of residue products, such as wood and peat ashes.     

Forms and extractability of manganese in potting media

Abstract

Sequential extraction of pine bark medium alone and after amendment with either manganese sulfate (MnSO₄), composted rice hulls, or soil showed that at pH 5.5–7.0 most of the manganese (Mn) exists in a form that is extracted by acidic hydroxylamine hydrochloride, and which could therefore be in oxide or strongly‐bound forms. Acidification to pH 4.5–5.0 transferred large amounts of this ‘oxide’ Mn into ‘readily available’ and ‘weakly adsorbed’ fractions. Similar extractions of Sitka spruce bark showed that most of its Mn was extracted by weak cationic reagents ('readily available’ and ‘weakly adsorbed’ fractions). Growth of oats in pine bark, peat, and eucalypt sawdust media, with and without MnSO₄ amendment, lowered the amounts of Mn in ‘readily soluble’ and ‘weakly adsorbed’ fractions and caused some loss of ‘oxide’ Mn. Comparison of data for Mn extracted by 2 mM DTPA (1:1.5 v/v) with Mn in sequential fractions showed that DTPA dissolves some ‘oxide’ Mn. The data further suggest that up to about 36 mg/L DTPA‐extractable Mn would not be toxic to most plants growing in media of pH 6.0, but 60 mg/L DTPA‐extractable Mn may be if the medium pH falls below 5.5.     

Land evaluation for forestry: a study of the land requirements for growing Pinus radiata D. Don in the Basque Country, northern Spain

Land requirements for the growth of Pinus radiata D. Don were studied in 112 plots by comparing site index (SI) values with land characteristics. The SI at the reference age of 20 years ranged from 10.4 to 32.7 m. The growth of Radiata pine increased as soil rootable depth increased, with a mean depth of about 50 cm in plots with an SI higher than 29 m. The results show that soil physical properties had a major influence on growth rates with soils of a loamy texture resulting in higher rates than clay rich soils. Soil nitrogen and phosphorus availability had significant effects on growth on soils developed on non‐volcanic parent material whilst potassium availability was significant in soils on volcanic parent material. There were strong interactions among the land characteristics of each land unit so that the magnitude of the specific effect of a given variable was highly dependent on the values of the others. Results are discussed in relation to land use planning.     

Microbial biomass and activity in soil and litter underPinus sylvestris, Picea abies andBetula pendula at originally similar field afforestation sites

Microbial biomass C and N, and activities related to C and N cycles, were compared in needle and leaf litter, and in the uppermost 10 cm of soil under the litter layer in Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies L.) and silver birch (Betula pendula L.) stands, planted on originally similar field afforestation sites 23–24 years ago. The ground vegetation was differentiated under different tree species, consisting of grasses and herbs under birch and pine, and mosses or no vegetation with a thick layer of needles under spruce. The C:N ratio of the soils was 13–21 and the soil pH_{CaCl 2} 3.8–5.2. Both showed little variation under different tree species. Microbial biomass C and N, C mineralization, net ammonification, reduction) did not differ significantly in soil under different tree species either. Birch leaf litter had a higher pH_{CaCl 2} (5.9) than spruce and pine needle litter (pH 5.0 and 4.8, respectively). The C:N ratio of spruce needles was 30, and was considerably higher in pine needles (69) and birch leaves (54). Birch leaves tended to have the highest microbial biomass C and C mineralization. Spruce needles appeared to have the highest microbial biomass N and net formation of mineral N, whereas formation of mineral N in pine needles and birch leaves was negligible. Microbial biomass C and N were of the same order of magnitude in the soil and litter samples but C mineralization was tenfold higher in the litter samples.     

Changes in the temperature regime of podzolic soils in the course of natural forest restoration after clearcutting

The results of temperature monitoring in podzolic soils under the middle-taiga bilberry spruce forest and secondary mixed forest of the Komi Republic performed in 2008–2014 are presented. The changes in characteristics of soil temperature in the litter horizon and in the mineral horizons at the depths of 20 and 50 cm are outlined. It is shown that soil temperature regimes differ under the native spruce forest, young growth, and middle-aged secondary mixed forest. The soils of secondary phytocenoses are warmed up to a greater depth and are characterized by the higher heat supply. The differences are seen in a number of temperature parameters, such as the accumulated temperatures above 5°C and above 10°C at the depths of 20 and 50 cm. The most significant differences between the studied plots manifest themselves in the values of temperature amplitudes during the warm season. Maximum values of daily temperature amplitudes were obtained on the plot under young growth, whereas the soil under the middle-aged mixed forest was characterized by minimum values of daily temperature amplitudes.     

Effects of forest vegetation on spatial variability of surface mineral soil pH,soluble aluminum and carbon

The purpose of this study was to examine spatial variability in forest soils at several levels including variability due to soil structure, to the presence of individual trees and to populations of different species of trees. Both classic statistical and geostatistical methods were used. Soil chemical properties measured include pH and Al and C in solution which was in equilibrium with the surface mineral soil. Results indicated that soil cores 1.8 cm in diameter were as effective as larger cores in incorporating variability in surface mineral soil pH. There was no spatial correlation in soil pH in samples separated by a distance of 20 to 360 cm. The presence of individual Norway spruce and red pine trees affected soil in their vicinity. Soil pH was depressed and soluble Al elevated. in soil near the base of the tree compared to soil 120 cm from the tree, independent of direction. In addition, in soil sampled at least 100 cm from the base of trees, pH was lower in Norway spruce compared to sugar maple plantations and soluble C was greater in red pine compared to Norway spruce plantations. It is concluded that in less than 50 yr the presence of individual trees and populations of different tree species can affect chemical properties of surface mineral soils. These effects should be considered in the design and interpretation of experiments.     

Are Indicators for Critical Load Exceedance Related to Forest Condition?

The aim of this study was to evaluate the suitability of the (Ca?+?Mg?+?K)/Al and the Ca/Al ratios in soil solution as chemical criteria for forest condition in critical load calculations for forest ecosystems. The tree species Norway spruce, Sitka spruce and beech were studied in an area with high deposition of sea salt and nitrogen in the south-western part of Jutland, Denmark. Throughfall and soil water were collected monthly and analysed for pH, NO₃-N, NH₄-N, K, Ca, Mg, DOC and Al_tot. Organic Al was estimated using DOC concentrations. Increment and defoliation were determined annually, and foliar element concentrations were determined every other year. The throughfall deposition was highest in the Sitka spruce stand (maximum of 40 kg N ha^?1yr^?1) and lowest in the beech stand (maximum of 11 kg N ha^?1yr^?1). The Sitka spruce stand leached on average 12 kg N ha^?1yr^?1 during the period 1988–1997 and leaching increased throughout the period. Only small amounts of N were leached from the Norway spruce stand whereas almost no N was leached from the beech stand. For all tree species, both (Ca?+?Mg?+?K)/Al and Ca/Al ratios decreased in soil solution at 90 cm depth between 1989 and 1999, which was mainly caused by a decrease in concentrations of base cations. The toxic inorganic Al species were by far the most abundant Al species at 90 cm depth. At the end of the measurement period, the (Ca?+?Mg?+?K)/Al ratio was approximately 1 for all species while the Ca/Al ratio was approximately 0.2. The lack of a trend in the increment rates, a decrease in defoliation as well as sufficient levels of Mg and Ca in foliage suggested an unchanged or even slightly improved health condition, despite the decreasing and very low (Ca?+?Mg?+?K)/Al and Ca/Al ratios. The suitability of these soil solution element ratios is questioned as the chemical criteria for soil acidification under field conditions in areas with elevated deposition rates of sea salts, in particular Mg.