Effects of calcined magnesite,magnesium hydroxide and “geosan” on soil properties in declining spruce stands (NE Bavaria)

The results of pH-stat.-titrations at six pH levels show increasing reactivities of the fertilizers under investigation in the order magnesite < Geosan < Mg-hydroxide. Further differences exist in the acid neutralization capacity of the three samples. By 3 mo after fertilization, Mg concentrations in soil solution down to 70 cm soil depth significantly increased. Differences between the fertilizers reflect their reactivities. Fertilization increases soil nitrate concentrations by 50 to 100% up to 55 ppm. It is unclear why the control plots already show high nitrate contents in soil solution. The top mineral soil shows significant increases of base saturation after fertilization. The highly reactive Mg-hydroxide produces the highest Mg concentrations in the soil solution, whereas the slower soluble magnesite has a stronger effect on the exchange complex.     

Effects of calcined magnesite,magnesium hydroxide and “geosan” on soil properties in declining spruce stands (NE Bavaria)

The results of pH-stat.-titrations at six pH levels show increasing reactivities of the fertilizers under investigation in the order agnesite < Geosan < Mg-hydroxide. Further differences exist in the acid neutralization capacity of the three samples. By 3 mo after fertilization, Mg concentrations in soil solution down to 70 cm soil depth significantly increased. Differences between the fertilizers reflect their reactivities. Fertilization increases soil nitrate concentrations by 50 to 100% up to 55 ppm. It is unclear why the control plots already show high nitrate contents in soil solution. The top mineral soil shows significant increases of base saturation after fertilization. The highly reactive Mg-hydroxide produces the highest Mg concentrations in the soil solution, whereas the slower soluble magnesite has a stronger effect on the exchange complex.     

Amelioration of Magnesium Deficiency in a Norway Spruce Stand (Picea abies) with Calcined Magnesite

Norway spruce has shown needle yellowing and defoliation symptoms on manysites of the Bohemian Forest in north central Austria since theearly 1980s. A forest amelioration experiment was set up toevaluate the response of spruce to magnesite based fertilizerswith different solubilities. Response variables were a crownvigor index, diameter growth, nutrient contents in needles,soil solution chemistry, and soil chemistry. Soil solution atfertilized plots showed an immediate response in base cationconcentrations, nitrate concentrations and pH-values.Fertilization increased the pool of exchangeable cations in theupper 15 cm of the soil and reduced levels of exchangeable Al. Themagnesium and calcium content of the needles of dominant trees wasgreatly improved. Fertilization has increased the mineralizationrate of soil organic matter. Diameter growth, as a measure of treevigor, showed a pronounced positive response with a time delay of5 years. Our results demonstratethat magnesite based fertilizers are a viable option to improvethe nutritional status of spruce forests on granitic bedrock.     

Effects of Serpentinite Fertilization with N,P, and K Fertilizers on Soil Properties and Needle Chemistry

The aim of the present research was to study the long-term effect of serpentinite fertilization with additional nitrogen, phosphorous, and potassium fertilizers on some physicochemical properties and the enzyme activity of acidic soils and needle chemistry in stands of Norway spruce (Picea abies (L.) Karst.). Experimental plots were located in spruce stands in the middle forest zone (900–950 m) on two nappes of the Carpathian flysch: Magura and Silesian. Serpentinite was introduced in autumn 2008 on all plots while the other fertilizers in spring 2009. The effect of fertilization was visible mainly in the humus horizon. No significant changes were found in the deeper mineral soil. The acidity and Al toxicity in the surface horizon were ameliorated through serpentinite fertilization. Five years after fertilization, no significant difference in the fertilization treatments was noted in the chemistry of the spruce needles.     

The influence of Mg fertilization on growth and mineral contents of fine roots in (Picea abies [karst] L.) stands at different stages of decline in NE-Bavaria

The effect of various Mg-fertilizers (MgSO₄; calcined dolomite) on root growth and mineral composition of 40 yr old Norway spruce at different sites and stages of decline was studied. Two years after fertilization, density of living fine roots of Mg-deficient trees had significantly increased on fertilized compared to non-fertilized plots. Only fertilization of calcined dolomite appeared to induce new root formation in the upper mineral soil. No such changes were observed for healthy looking trees at a second experimental site, where base saturation of the bulk soil was also low but trees were sufficiently supplied with Mg. At the third experimental site where foliar analyses reflected a luxurious Ca and Mg but an insufficient K nutrition at high Mg and Ca saturation of the bulk soil, calcined dolomite caused an increase of root growth due to a reinforced antagonism between Ca and Mg competing with K uptake. In general, at the experimental sites the fine root necromass decreased when base saturation of the bulk soil increased. The elemental contents of fine roots from the mineral soil of all three sites under investigation indicated that fine root growth in the mineral soil is strongly related to the root Ca and Mg contents. Root Ca contents seemed to be mainly a function of the Ca availability in the soil. Since there was no close relationship between fine root growth and the Ca/AI molar ratio in living fine roots, Al toxicity may not completely account for the differences in root growth and nutrition on the experimental sites.     

施肥深度和用量对华南果园土壤氮磷流失的影响

Fertilizers are heavily applied in orchards of the hilly and mountainous topography of South China and may increase nutrient loadings to receiving waters. A simple runoff collecting system was used to measure the effects of different fertilization treatments on total N and P concentrations of surface runoff in a Chinese chestnut （Castanea mollissima Blume） orchard in Dongyuan County, Guangdong Province, China. In such orchards, fertilizer was typically applied in two short furrows or pits on either side of each tree. Treatments included three application depths （surface, 10 cm and 20 cm）, and three application rates （low, median and high）. Results showed that 90.5% of the runoff water samples had a total N concentration higher than 0.35 mg·L^-1 and 54.2% had a total P concentration higher than 0.1 mg·L^-1. Fertilizer application at all depths and at all but the lowest rate significantly increased total N and P concentrations in runoff water. Fertilization with chemical compound fertilizer at a soil depth of 20 cm produced significantly lower （P 〈 0.05） total N concentration in runoff than both surface and 10-cm depth fertilization, and significantly lower （P 〈 0.05） total P concentration in runoff than surface fertilization. Total N and P concentrations in runoff significantly increased with the application rate of organic fertilizers. With the exception of total P concentrations, which were not significantly different between the control and fertilization at a rate of 119 kg P ha-1 in organic form, all the other fertilization treatments produced significantly higher total N and total P concentrations in runoff than the control. A fertilization depth ≥ 20 cm and an application rate ≤ 72 kg N ha-1 or 119 kg P ha^-1 for compound organic fertilizer was suggested to substantially reduce N and P runoff losses from hillslope orchards and to protect receiving waters in South China.     

The influence of Mg fertilization on growth and mineral contents of fine roots in (Picea abies [Karst] L.) stands at different stages of decline in NE-Bavaria

The effect of various Mg-fertilizers (MgSO₄; calcined dolomite) on root growth and mineral composition of 40 yr old Norway spruce at different sites and stages of decline was studied. Two years after fertilization, density of living fine roots of Mg-deficient trees had significantly increased on fertilized compared to non-fertilized plots. Only fertilization of calcined dolomite appeared to induce new root formation in the upper mineral soil. No such changes were observed for healthy looking trees at a second experimental site, where base saturation of the bulk soil was also low but trees were sufficiently supplied with Mg. At the third experimental site where foliar analyses reflected a luxurious Ca and Mg but an insufficient K nutrition at high Mg and Ca saturation of the bulk soil, calcined dolomite caused an increase of root growth due to a reinforced antagonism between Ca and Mg competing with K uptake. In general, at the experimental sites the fine root necromass decreased when base saturation of the bulk soil increased. The elemental contents of fine roots from the minenal soil of all three sites under investigation indicated that fine root growth in the mineral soil is strongly related to the root Ca and Mg contents. Root Ca contents seemed to be mainly a function of the Ca availability in the soil. Since there was no close relationship between fine root growth and the Ca/Al molar ratio in living fine roots, Al toxicity may not completely account for the differences in root growth and nutrition on the experimental sites.     

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.     

Water,nutrient and pollutant budgets in damaged Norway spruce stands in NE-Bavaria (F.R.G.) and their changes after different fertilization treatments

Water budgets and ecosystem balances of the main nutrients and pollutants were calculated in two Norway spruce forests at different states of decline in the Fichtelgebirge (F.R.G.) from summer 1984 through summer 1986. For that purpose, samples of precipitation, throughfall, litter seepage and soil solution were gathered weekly. Fluxes of main cations and anions were calculated by multiplying water fluxes through the different compartments with the appropriate ion concentrations. Both spruce stands are characterized by a sufficient water supply throughout the investigation period caused by high annual precipitation. Only in dry periods drastical restriction of plant available water may endanger those spruces growing on very stony podzols and cambisols. The calculation of deposition fluxes differentiates the damaged and the apparently healthy spruce stand. Input of SO₂ and H⁺ as well as canopy buffering and K-leaching of the canopies are significantly higher in the damaged spruce stand than in the healthy one. Additionally, the exchangeable base cation content of the soil on the damaged site is nearly exhausted and therefore buffering capacity in the soil differs from those of the healthy site. There was a low increase of N0₃-leaching with seepage after the fertilization with high amounts of lime.     

Der Einfluß von Fichtennadelwachs auf Nadelzersetzung und Erlenkeimung

The influence of spruce needle wax on the degradation of the needles and the germination of alder seeds 1- and 3-year old needles of Picea abies, each untreated or with the wax layer removed, were burried in a field. Dry-weight of needles without wax decreased faster during an exposition period of 1 to 5 months. Because the wax proved to be a highly selective substrate for microbial colonisation, it retarded the needle degradation. Wax on 1-year old needles slowed degradation down during 2 months, wax on 3-year old needles during 5 months. Degradation time varied for different wax components. The site of wax decomposition was determined by analysing the lipids eluted from different soil layers (depth 0–30 cm) in a natural spruce forest. Lipids forming the wax decreased in depth 1–5 cm and were missing in depth 7–14 cm. Microorganisms isolated from 3 soil layers (depth 1–7 cm) were able to use fatty acids and fatty alcohols out of the wax as a carbon source. But only microorganisms from depth 7–14 cm degraded all wax components. Wax of 1-year old needles delayed seed germination (Alnus glutinosa) for 6 days. Wax of 3-year old needles delayed and inhibited germination for at least 12 days. Pure stearic acid did not influence germination. The different effects show the importance of the chemical wax composition rather than of the water repellent property.     

The use of organic and mineral fertilizers in reforestation and in revitalization of declining protective forests in the Alps

BIOSOL and BACTOSOL, organic fertilizers based on residue from commercial antibiotic production, were tested as an alternative to mineral fertilizers in reforestation and in revitalization of Norway spruce stands (Picea abies) affected by forest decline. Due to its slow release of N and its stimulation of root growth, the organic fertilizer was superior to mineral fertilizer in enhancing growth of spruce planted in nutrient poor soil with low nutrient retention capacity, especially when combined with magnesium carbonate fertilizer. In mature stands, basal area increment responded positively and significantly to both mineral fertilizer and BIOSOL. So far no pronounced effects of fertilizer treatment on seed production and viability were observed. Fertilization in the moderate amounts employed had no adverse effects on microbial activity in the soil and mycorrhizal status and thus seems to be a safe method to increase tree vigor without dramatically changing site parameters.     

Changes in soil ph over a 50-year period under different forest canopies in SW Sweden

Reinvestigation of soil profiles, down to 70 cm depth in mineral soil, sampled for measurements in 1927 revealed a general decrease in pH for spruce and hardwood stands with 0.3 to 0.9 units. The pH-changes in the top soil can partly be explained by biological acidification, increasing with stand age. Stand age and species composition have less influence in deeper soil horizons and much of the acidification there is ascribed to acid deposition.     

Conversion of cropland to forest increases soil CH4 oxidation and abundance of CH4 oxidizing bacteria with stand age

We investigated CH₄ oxidation in afforested soils over a 200-year chronosequence in Denmark including different tree species (Norway spruce, oak and larch) and ages. Samples of the top mineral soil (0–5 cm and 5–15 cm depth) were incubated and analyzed for the abundance of the soil methane-oxidizing bacteria (MOB) and ammonia-oxidizing bacteria (AOB) and archaea (AOA) based on quantitative PCR (qPCR) on pmoA and amoA genes. Our study showed that CH₄ oxidation rates and the abundance of MOB increased simultaneously with time since afforestation, suggesting that the methanotrophic activity is reflected in the abundance of this functional group.The development of forest soils resulted in increased soil organic carbon and reduced bulk density, and these were the two variables that most strongly related to CH₄ oxidation rates in the forest soils. For the top mineral soil layer (0–5 cm) CH₄ oxidation rates did not differ between even aged stands from oak and larch, and were significantly smaller under Norway spruce. Compared to the other tree species Norway spruce caused a decrease in the abundance of MOB over time that could explain the decreased oxidation rates. However, the cause for the lower abundance remains unclear. The abundance of ammonia-oxidizers along the chronosequence decreased over time, oppositely to the MOB. However, our study did not indicate a direct link between CH₄ oxidation rates and ammonia-oxidizers. Here, we provide evidence for a positive impact of afforestation of former cropland on CH₄ oxidation capacity in soils most likely caused by an increased population size and activity of MOB.     

Long‐term development of nitrogen fluxes in a coniferous ecosystem: Does soil freezing trigger nitrate leaching?

In many forest ecosystems chronically large atmospheric deposition of N has caused considerable losses of inorganic N by seepage. Freezing and thawing of soil may alter the N turnover in soils and thereby the interannual variation of N seepage fluxes, which in turn makes it difficult to evaluate the N status of forest ecosystems. Here, we analyzed long‐term monitoring data of concentrations and fluxes of dissolved inorganic N (DIN) in throughfall and seepage from a Norway spruce stand at the Fichtelgebirge (SE Germany) between 1993 and 2004. Despite constant or even slightly increasing N inputs in throughfall, N losses with seepage at 90 cm declined from 15–32 kg N ha^–1 y^–1 in the first years of the study period (1993–1999) to 3–10 kg N ha^–1 y^–1 in 2000 to 2004. The large N losses in the first years coincided with extreme soil frost in the winter of 1995/96, ranging from –3.3°C to –1.0°C at 35 cm soil depth. Over the entire observation period, maximum fluxes of nitrate and ammonium were observed in the mineral soil following thawing of the soil. The elevated ammonium and nitrate fluxes resulted apparently from increased net ammonification and nitrification rates in the mineral soil, whereas mineral‐N fluxes in the O horizon were less affected by frost. Our data suggest that (1) extreme soil frost may cause substantial annual variations of nitrate losses with seepage and that (2) the assessment of the N status of forest ecosystems requires long periods of monitoring. Time series of biogeochemical data collected over the last 20–30 y include years with extreme cold winters and warm summers as well as unusual precipitation patterns. Analysis of such long‐term monitoring data should address climate extremes as a cause of variation in N outputs via leaching. The mean loss of 14.7 kg N with seepage water during 12 y of observation suggests that the forest ecosystem was saturated with N.     

Heavy Metal Concentrations in Soil Solution, Soil and Needles in a Norway Spruce Stand on an Acid Sulphate Forest Soil

The effects of soil processes, related to the oxidation of sulphide sediments, on heavy metal concentrations in the soil and soil solution were investigated in a Norway spruce stand on a fine-textured, acidic soil rich in sulphates located on the isostatic land-uplift western coast of Finland. The age of the soil is ca. 300–400 years, and the soil texture is silt and till. The chemical properties of the soil and soil solution clearly reflected the formation of acid sulphate (AS) soil. Compared to background reference values for podzolic coniferous forest soil, the pH of the soil solution in the mineral soil (20–40 cm depth) was very low, and the Al, Fe and S concentrations extremely high. The Zn and Ni concentrations in the soil solution were also strongly elevated, and similar to the concentrations reported close to anthropogenic heavy-metal emission sources. The concentrations of Cd and Cu were also frequently elevated. In contrast, the acidity and metal concentrations of the soil solution sampled in the organic layer were not elevated. Similarly, exchangeable Zn and Ni concentrations were also elevated in the mineral soil, but not in the organic layer. Because Norway spruce has a very superficial rooting system and the zone with exceptionally high metal concentrations did not extend up to the topmost soil layers, sulphide-oxidation derived soil acidification is not likely to pose a serious threat to forest ecosystems growing on this type of site. Despite the elevated concentrations of protons and many metals in the mineral soil and soil solution (20–40 cm), the nutrient status of the spruce stand was satisfactory and the general health of the stand has been reported to be relatively good.     

Acid deposition in the German solling area: Effects on soil solution chemistry and Al mobilization

The Al chemistry of soil solutions was evaluated in two forest ecosystems in the North-German Solling area which is heavily impacted by acidic deposition. The principal H⁺ buffering process in these soils is the release of Al ions. Within the stand of Norway spruce, Al concentrations increase with soil depth up to 370 umol/L. Ca/Al ratios of the soil solution decrease with depth and suggest high risk of Al toxicity to tree roots and potential antagonistic effects for ion uptake. The Al concentrations of the soil solution in the upper horizons do not appear to be in equilibrium with mineral phases of Gibbsite, Alunite and Jurbanite as suggested by the depth gradients and temporal patterns in ion activity products. Depletion of extractable soil Al in the upper horizons is occuring. The release of Al to the soil solution under these conditions seems to be restricted by kinetic constraints.     

Short-Term Influence of Clinker Dust and Wood Ash on Macronutrients and Growth in Norway Spruce (Picea abies) and Scots Pine (Pinus sylvestris) Seedlings

The effects of clinker dust and wood ash on Norway spruce and Scots pine seedlings were compared in buried pots. Clinker dust (0.5 kg m^?2) and wood ash (0.5 kg m^?2) were applied to the surface of a nutrient-poor mineral soil. In the second year, the increase in soil pH by the dust and ash were larger than in the first year. Both alkaline treatments caused a large increase in the needle potassium (K) concentration. An excess of soil K relative to magnesium (Mg) was observed by decreased Mg concentration in needles shortly after treatment. However, Mg concentration in needles stayed in the sufficiency range. Current results confirmed earlier findings that despite a positive effect on base cation nutrition, wood ash has a low potential for increasing the biomass of forest stands on mineral soils due to the N limitation in these soils.     

Effects of air pollutants on mineral nutrition of Norway spruce and revitalization of declining stands in Austria

The vigor of Norway spruce stands in the Bohemian Forest of Austria was correlated with site factors, informations on historic land use, and chemical properties of the soils and spruce needles. The study confirmed that trees on west exposed slopes and plateaus in higher elevation have lower crown densities. The soils in the area are generally low in base saturation. Historical land use, such as litter raking, grazing and burning of biomass for potash led to nutrient depletion. Increasing deposition of atmospheric N during the last decades alleviated N stress, but increased Ca and Mg stress. N∶Mg ratios in needles of declining stands are wide, indicating N induced nutritional imbalances. PH values in the mineral topsoil are very low on W-slopes and plateaus. Measurements of pollutant deposition at three different sites indicate a strong influence of aspect and elevation on input rates. In a southwest exposed stand and a stand on a hilltop, facing the prevailing winds, substantially more S and N was recovered in the throughfall than in northeast exposed stand. Deposition rates in the open did not differ significantly. High NO₃ ^? concentrations in the soil solution of the southwest exposed site indicate N saturation of the system. In order to test the hypothesis that mineral deficiency and nutritional disorders contribute to the poor vigor of these stands, fertilizer experiments were established. Fertilization with a combination of an organic fertilizer (BACTOSOL^**)) and a magnesite fertilizer (BIOMAG^*)) significantly improved crown density, growth, seed viability, and mineral nutrition as inferred from foliar analysis. NO₃ ^? leaching in the combined BACTOSOL+BIOMAG treatment increased during the first and second growing season after fertilization but leveled off to values typical for the control plots after three years. Mg content of the soil solution increased both in the BIOMAG and the combined BACTOSOL+BIOMAG treatment. These experiments show that the nutritional status and the resilience of declining forests in the Bohemian Forests of Austria can be easily improved by proper fertilizer treatment.     

Vertical transport of decomposing spruce needles during nine years in a raw humus soil profile in southern Norway

In a podsol profile, the amount of time passed after spruce (Picea abies) needles fall from the trees is correlated with their depth position in the organic soil layer. This relationship was examined by dropping marked needles in small patches on the ground and collecting them at various intervals during the following nine years. Needles dropped in moss-covered patches mostly reached the dense needle mat at the bottom of the green moss (“zero depth”) after about one year. After two years, it was estimated that about 60% of the initial dry mass was lost. After three years, the needles had an average depth position of 1 cm below “zero”, corresponding to the transition between the O_l and O_f layer. Needles of the same age were situated at varying depths, mainly because of variation between individual patches, but also because not all needles were caught by the moss vegetation at the start. The downward transport rate slowed down with time. After nine years, the mean needle depth was 3.1 cm below “zero”, about halfway to the bleached mineral layer and in the upper part of the fine root layer. Needles situated close to roots were often almost completely disintegrated. The total vertical transport through the organic layer evidently takes many decades. Needles dropped on bare needle mats underneath large trees had a mean depth position of 1.6 cm after nine years.     

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.