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  • 1
    Language: English
    In: Plant and Soil, 2013, Vol.371(1), pp.435-446
    Description: Background and aims: The partitioning of below ground carbon inputs into roots and extramatrical ectomycorrhizal mycelium (ECM) is crucial for the C cycle in forest soils. Here we studied simultaneously the newly grown biomass of ECM and fine roots in a young Norway spruce stand. Methods: Ingrowth mesh bags of 16 cm diameter and 12 cm height were placed in the upper soil and left for 12 to 16 months. The 2 mm mesh size allowed the ingrowth of fungal hyphae and roots whereas a 45 mu m mesh size allowed only the ingrowth of hyphae. The mesh bags were filled with either EA horizon soil, pure quartz sand or crushed granite. Controls without any ingrowth were established for each substrate by solid tubes (2010) and by 1 mu m mesh bags (2011). The fungal biomass in the substrates was estimated by the PLFA 18:2 omega 6,9 and ECM biomass was calculated as difference between fungal biomass in mesh bags and controls. Results: The maximum ECM biomass was 438 kg ha super(-1) in October 2010 in 2 mm mesh bags with EA substrate, and the minimum was close to zero in 2011 in 45 mu m mesh bags with quartz sand. The high P content of the crushed granite did not influence the ECM biomass. Fine root biomass reached a maximum of 2,343 kg ha super(-1) in October 2010 in mesh bags with quartz sand after 16 months exposure. In quartz sand and crushed granite, ECM biomass correlated positively with fine root biomass and the number of root tips, and negatively with specific root length. Conclusion: The ratio of ECM biomass/fine root biomass in October ranged from 0.1 to 0.3 in quartz sand and crushed granite, but from 0.7 to 1.8 in the EA substrate. The results for the EA substrate suggest a large C flux to ECM under field conditions.
    Keywords: Biomass ; Ectomycorrhizal mycelium ; Fine roots ; Ingrowth bags ; Substrate quality ; Norway spruce
    ISSN: 0032-079X
    E-ISSN: 1573-5036
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  • 2
    Language: English
    In: Plant and Soil, 2014, Vol.378(1), pp.73-82
    Description: Background and aims Partitioning of soil respiration is a challenging task when resolving the C cycling in forest ecosystems. Our aim was to partition the respiration of newly grown extramatrical ectomycorrhizal mycelium (ECM) and fine roots (and their associated microorganisms) in a young Norway spruce forest. Methods Ingrowth mesh bags of 16 cm diameter and 12 cm height were placed in the upper soil and left for 12-16 months in 2010 and 2011. The 2 mm mesh size allowed the ingrowth of ECM and fine roots whereas a 45 [micro]m mesh size allowed only the ingrowth of ECM. The mesh bags were filled with either homogenized EA horizon soil, pure quartz sand (QS) or crushed granite (CG, only 2011), each with five replicates. Controls without any ingrowth were established for each substrate by solid plastic tubes (2010) and by 1 [micro]m mesh bags (2011). Fluxes of C[O.sub.2] from the mesh bags and controls were measured biweekly during the growing season by the closed chamber method. Results The contribution of ECM to soil respiration was largest in the QS treatments, reaching cumulatively 1.2 and 2.2 Mg C [ha.sup.-1] 6 [months.sup.-1] in 2010 and 2011, respectively. For EA and CG treatments, the cumulative respiration from ECM was larger than from controls, however the differences being not statistically significant. The respiration of newly grown fine roots in QS amounted to 1.0 Mg C [ha.sup.-1] in 2010, but could not be identified in 2011 since fluxes from 2 mm and 45 [micro]m mesh bags were similar. The correlation of total root length in single QS mesh bags to C[O.sub.2] fluxes was poor. The contribution of fine root respiration was also not detectable in the EA and CG treatment. No correlation was found between the autumnal biomass of newly grown ECM and its cumulative respiration. Conclusion Our results suggest a substantial contribution of newly grown ECM to soil respiration. Respiration of ECM might be larger than respiration of fine roots. Keywords Soil respiration * Carbon allocation * Ectomycorrhiza * Picea abies * Fine roots
    Keywords: Soil respiration ; Carbon allocation ; Ectomycorrhiza ; Picea abies ; Fine roots
    ISSN: 0032-079X
    E-ISSN: 1573-5036
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  • 3
    Language: English
    In: Plant and Soil, 2007, Vol.292(1), pp.79-93
    Description: Fine root systems may respond to soil chemical conditions, but contrasting results have been obtained from field studies in non-manipulated forests with distinct soil chemical properties. We investigated biomass, necromass, live/dead ratios, morphology and nutrient concentrations of fine roots (〈2 mm) in four mature Norway spruce ( Picea abies [L.] Karst.) stands of south-east Germany, encompassing variations in soil chemical properties and climate. All stands were established on acidic soils (pH (CaCl 2 ) range 2.8–3.8 in the humus layer), two of the four stands had molar ratios in soil solution below 1 and one of the four stands had received a liming treatment 22 years before the study. Soil cores down to 40 cm mineral soil depth were taken in autumn and separated into four fractions: humus layer, 0–10 cm, 10–20 cm and 20–40 cm. We found no indications of negative effects of N availability on fine root properties despite large variations in inorganic N seepage fluxes (4–34 kg N ha −1  yr −1 ), suggesting that the variation in N deposition between 17 and 26 kg N ha −1  yr −1 does not affect the fine root system of Norway spruce. Fine root biomass was largest in the humus layer and increased with the amount of organic matter stored in the humus layer, indicating that the vertical pattern of fine roots is largely affected by the thickness of this horizon. Only two stands showed significant differences in fine root biomass of the mineral soil which can be explained by differences in soil chemical conditions. The stand with the lowest total biomass had the lowest Ca/Al ratio of 0.1 in seepage, however, Al, Ca, Mg and K concentrations of fine roots were not different among the stands. The Ca/Al ratio in seepage might be a less reliable stress parameter because another stand also had Ca/Al ratios in seepage far below the critical value of 1.0 without any signs of fine root damages. Large differences in the live/dead ratio were positively correlated with the Mn concentration of live fine roots from the mineral soil. This relationship was attributed to faster decay of dead fine roots because Mn is known as an essential element of lignin degrading enzymes. It is questionable if the live/dead ratio can be used as a vitality parameter of fine roots since both longevity of fine roots and decay of root litter may affect this parameter. Morphological properties were different in the humus layer of one stand that was limed in 1983, indicating that a single lime dose of 3–4 Mg ha −1 has a long-lasting effect on fine root architecture of Norway spruce. Almost no differences were found in morphological properties in the mineral soil among the stands, but vertical patterns were apparently different. Two stands with high base saturation in the subsoil showed a vertical decrease in specific root length and specific root tip density whereas the other two stands showed an opposite pattern or no effect. Our results suggest that proliferation of fine roots increased with decreasing base saturation in the subsoil of Norway spruce stands.
    Keywords: Ca/Al ratio ; Fine roots ; Fine root biomass ; Fine root morphology ; Liming ; Mn concentration ; Nitrogen deposition ; Norway spruce
    ISSN: 0032-079X
    E-ISSN: 1573-5036
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  • 4
    Language: English
    In: Plant and Soil, 1 November 2007, Vol.300(1/2), pp.21-34
    Description: Forest soils are frequently subjected to dry-wet cycles, but little is known about the effects of repeated drying and wetting and wetting intensity on fluxes of $\mathrm{N}{\mathrm{H}}_{4}^{+}$, $\mathrm{N}{\mathrm{O}}_{3}^{-}$ and DOC. Here, undisturbed soil columns consisting of organic horizons (O columns) and organic horizons plus mineral soil (O+M columns) from a mature Norway spruce stand at the Fichtelgebirge; Germany, were repeatedly desiccated and subsequently wetted by applying different amounts of water (8, 20 and 50 mm day-1) during the initial wetting phase. The constantly moist controls were not desiccated and received 4 mm day-1 during the entire wetting periods. Cumulative inorganic N fluxes of the control were 12.4 g N m-2 (O columns) and 11.4 g N m-2 (O+M columns) over 225 days. Repeated drying and wetting reduced cumulative $\mathrm{N}{\mathrm{H}}_{4}^{+}$ and $\mathrm{N}{\mathrm{O}}_{3}^{-}$ fluxes of the O columns by 47–60 and 76–85%, respectively. Increasing $\mathrm{N}{\mathrm{H}}_{4}^{+}$ (0.6–1.1 g N m-2) and decreasing $\mathrm{N}{\mathrm{O}}_{3}^{-}$ fluxes (7.6–9.6 g N m-2) indicate a reduction in net nitrification in the O+M columns. The negative effect of dry–wet cycles was attributed to reduced net N mineralisation during both the desiccation and wetting periods. The soils subjected to dry–wet cycles were considerably drier at the final wetting period, suggesting that hydrophobicity of soil organic matter may persist for weeks or even months. Based on results from this study and from the literature we hypothesise that N mineralisation is mostly constrained by hydrophobicity in spruce forests during the growing season. Wetting intensity did mostly not alter N and DOC concentrations and fluxes. Mean DOC concentrations increased by the treatment from 45 mg 1-1 to 61–77 mg 1-1 in the O tlsbba columns and from 12 mg 1-1 to 21–25 mg 1-1 in the O+M columns. Spectroscopic properties of DOC from the O columns markedly differed within each wetting period, pointing to enhanced release of rather easily decomposable substrates in the initial wetting phases and the release of more hardly decomposable substrates in the final wetting phases. Our results suggest a small additional DOC input from organic horizons to the mineral soil owing to drying and wetting.
    Keywords: Applied sciences -- Materials science -- Surface science ; Biological sciences -- Agriculture -- Agricultural sciences ; Biological sciences -- Agriculture -- Agricultural sciences ; Applied sciences -- Materials science -- Materials processing ; Biological sciences -- Agriculture -- Agricultural sciences ; Biological sciences -- Agriculture -- Agricultural sciences ; Biological sciences -- Agriculture -- Agricultural sciences ; Biological sciences -- Agriculture -- Agricultural sciences ; Biological sciences -- Biology -- Microbiology ; Biological sciences -- Agriculture -- Agricultural sciences
    ISSN: 0032079X
    E-ISSN: 15735036
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  • 5
    Language: English
    In: Plant and Soil, 2000, Vol.222(1), pp.149-161
    Description: Active tree roots influence the soil chemistry in their immediate vicinity, the rhizosphere. For the first time, the extent and stability of in situ concentration gradients of major cations and anions in the soil solution around tree roots were studied in the field. Micro suction cups were installed in an acidic forest soil using a root window in a 145-year-old Norway spruce stand. Samples were collected once a week during the growing season from the rhizosphere and from the bulk soil of a non-mycorrhizal long root and of a mycorrhizal root net. For comparison, micro suction cups were installed proximal and distal to a long root in a rhizotron under controlled conditions (homogenised soil, constant water potential, nutrient solution) at the same site. Small volumes of soil solutions were analysed for NH 4 + , K + , Na + , Ca 2+ , Mg 2+ , Al 3+ , NO 3 - , Cl - and SO 4 2- by capillary electrophoresis. Total-Al was measured with ICP-AES micro injection, complexed-Al was calculated as the difference between total-Al and Al 3+ . pH values were determined with an ion-sensitive field effect transistor (ISFET) sensor. In both set-ups a significant increase of the K + concentrations was observed in the rhizosphere as compared to the bulk soil solutions of the non-mycorrhizal long roots. The concentrations of Al 3+ , H + and NH 4 + were lower in the rhizosphere. No gradients were observed for Mg 2+ and Ca 2+ at the root window. A significant depletion of these ions was found in the rhizosphere of the long root only in the rhizotron. In the case of the mycorrhizal roots, contrasting results were found with significantly higher concentrations of Al 3+ , Mg 2+ , H + , SO 4 2- and Cl - , and significantly lower K + concentrations in the rhizosphere. The extension of the gradients was estimated at about 2.5 to 5 mm for the long roots and 1 mm for the mycorrhizal roots. The observed gradients varied strongly with time. In conclusion, for Norway spruce, the effect of non-mycorrhizal long roots on the rhizosphere chemistry differs from that of mycorrhizal roots. Evaluating nutrient availability and the risk of Al 3+ toxicity to tree roots from bulk soil analysis can be misleading.
    Keywords: aluminium complexation ; bulk soil ; Norway spruce ; nutrient concentration ; rhizosphere ; soil solution chemistry
    ISSN: 0032-079X
    E-ISSN: 1573-5036
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  • 6
    Language: English
    In: Plant and Soil, March, 2000, Vol.219(1), p.117
    Description: Byline: Shih-Chieh Chang (1), Egbert Matzner (1) Keywords: Fagus sylvatica L.; nitrification; nitrogen mineralization; nitrogen uptake; spatial heterogeneity; stemflow Abstract: In European beech (Fagus sylvatica L.) forests, a large proportion of the water and ion input to the soil results from stemflow which creates a soil microsite of high element fluxes proximal to the tree trunk. The soil proximal to the stem is considered to have different rates of nitrogen turnover which might influence the estimation of N-turnover rates at the stand scale. In a previous study we reported high nitrate fluxes with seepage proximal to the stems in a forest dominated by European beech in Steigerwald, Germany. Here, we investigated the soil nitrogen turnover in the top 15 cm soil in proximal (defined as 1 m.sup.2 around beech stems) and distal stem areas. Laboratory incubations and in situ sequential coring incubations were used to determine the net rates of ammonification, nitrification, and root uptake of mineral nitrogen. In the laboratory incubations higher rates of net nitrogen mineralization and nitrification were found in the forest floor proximal to the stem as compared to distal stem areas. No stem related differences were observed in case of mineral soil samples. In contrast, the in situ incubations revealed higher rates of nitrification in the mineral soil in proximal stem areas, while net nitrogen mineralization was equal in proximal and distal areas. In the in situ incubations the average ratio of nitrification/ammonification was 0.85 in proximal and 0.34 in distal stem areas. The net nitrogen mineralization was 4.4 g N m.sup.-2 90 day.sup.-1 in both areas. Mineralized nitrogen was almost completely taken up by tree roots with ammonium as the dominant nitrogen species. The average ratio of nitrate/ammonium uptake was 0.69 in proximal and 0.20 in distal areas. The higher water content of the soil in proximal stem areas is considered to be the major reason for the increased rates of nitrification. Different nitrogen turnover rates in proximal stem areas had no influence on the nitrogen turnover rates in soil at the stand scale. Consequently, the observed high nitrate fluxes with seepage proximal to stems are attributed to the high nitrogen input by stemflow rather than to soil nitrogen turnover. Author Affiliation: (1) Department of Soil Ecology, BITOK, University of Bayreuth, D-95440, Bayreuth, Germany Article History: Registration Date: 08/10/2004
    ISSN: 0032-079X
    Source: Cengage Learning, Inc.
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  • 7
    Language: English
    In: Plant and Soil, 2007, Vol.300(1), pp.21-34
    Description: Forest soils are frequently subjected to dry–wet cycles, but little is known about the effects of repeated drying and wetting and wetting intensity on fluxes of $${\text{NH}}^{{\text{ + }}}_{{\text{4}}} $$ , $${\text{NO}}^{ - }_{3} $$ and DOC. Here, undisturbed soil columns consisting of organic horizons (O columns) and organic horizons plus mineral soil (O + M columns) from a mature Norway spruce stand at the Fichtelgebirge; Germany, were repeatedly desiccated and subsequently wetted by applying different amounts of water (8, 20 and 50 mm day −1 ) during the initial wetting phase. The constantly moist controls were not desiccated and received 4 mm day −1 during the entire wetting periods. Cumulative inorganic N fluxes of the control were 12.4 g N m −2 (O columns) and 11.4 g N m −2 (O + M columns) over 225 days. Repeated drying and wetting reduced cumulative $${\text{NH}}^{{\text{ + }}}_{{\text{4}}} $$ and $${\text{NO}}^{ - }_{3} $$ fluxes of the O columns by 47–60 and 76–85%, respectively. Increasing $${\text{NH}}^{{\text{ + }}}_{{\text{4}}} $$ (0.6–1.1 g N m −2 ) and decreasing $${\text{NO}}^{ - }_{3} $$ fluxes (7.6–9.6 g N m −2 ) indicate a reduction in net nitrification in the O + M columns. The negative effect of dry–wet cycles was attributed to reduced net N mineralisation during both the desiccation and wetting periods. The soils subjected to dry–wet cycles were considerably drier at the final wetting period, suggesting that hydrophobicity of soil organic matter may persist for weeks or even months. Based on results from this study and from the literature we hypothesise that N mineralisation is mostly constrained by hydrophobicity in spruce forests during the growing season. Wetting intensity did mostly not alter N and DOC concentrations and fluxes. Mean DOC concentrations increased by the treatment from 45 mg l −1 to 61–77 mg l −1 in the O tlsbba columns and from 12 mg l −1 to 21–25 mg l −1 in the O + M columns. Spectroscopic properties of DOC from the O columns markedly differed within each wetting period, pointing to enhanced release of rather easily decomposable substrates in the initial wetting phases and the release of more hardly decomposable substrates in the final wetting phases. Our results suggest a small additional DOC input from organic horizons to the mineral soil owing to drying and wetting.
    Keywords: Dissolved organic carbon ; DOC properties ; Dry–wet cycles ; Forest soil ; Inorganic nitrogen ; Soil solution
    ISSN: 0032-079X
    E-ISSN: 1573-5036
    Source: Springer Science & Business Media B.V.
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  • 8
    Language: English
    In: Plant and Soil, 2000, Vol.218(1), pp.117-125
    Description: In European beech ( Fagus sylvatica L.) forests, a large proportion of the water and ion input to the soil results from stemflow which creates a soil microsite of high element fluxes proximal to the tree trunk. The soil proximal to the stem is considered to have different rates of nitrogen turnover which might influence the estimation of N-turnover rates at the stand scale. In a previous study we reported high nitrate fluxes with seepage proximal to the stems in a forest dominated by European beech in Steigerwald, Germany. Here, we investigated the soil nitrogen turnover in the top 15 cm soil in proximal (defined as 1 m 2 around beech stems) and distal stem areas. Laboratory incubations and in situ sequential coring incubations were used to determine the net rates of ammonification, nitrification, and root uptake of mineral nitrogen. In the laboratory incubations higher rates of net nitrogen mineralization and nitrification were found in the forest floor proximal to the stem as compared to distal stem areas. No stem related differences were observed in case of mineral soil samples. In contrast, the in situ incubations revealed higher rates of nitrification in the mineral soil in proximal stem areas, while net nitrogen mineralization was equal in proximal and distal areas. In the in situ incubations the average ratio of nitrification/ammonification was 0.85 in proximal and 0.34 in distal stem areas. The net nitrogen mineralization was 4.4 g N m -2 90 day -1 in both areas. Mineralized nitrogen was almost completely taken up by tree roots with ammonium as the dominant nitrogen species. The average ratio of nitrate/ammonium uptake was 0.69 in proximal and 0.20 in distal areas. The higher water content of the soil in proximal stem areas is considered to be the major reason for the increased rates of nitrification. Different nitrogen turnover rates in proximal stem areas had no influence on the nitrogen turnover rates in soil at the stand scale. Consequently, the observed high nitrate fluxes with seepage proximal to stems are attributed to the high nitrogen input by stemflow rather than to soil nitrogen turnover.
    Keywords: L. ; nitrification ; nitrogen mineralization ; nitrogen uptake ; spatial heterogeneity ; stemflow
    ISSN: 0032-079X
    E-ISSN: 1573-5036
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