Kooperativer Bibliotheksverbund

Language: English

In: Proceedings of the National Academy of Sciences of the United States of America, 24 November 2015, Vol.112(47), pp.14647-51

Description: The desiccation of upper soil horizons is a common phenomenon, leading to a decrease in soil microbial activity and mineralization. Recent studies have shown that fungal communities and fungal-based food webs are less sensitive and better adapted to soil desiccation than bacterial-based food webs. One reason for a better fungal adaptation to soil desiccation may be hydraulic redistribution of water by mycelia networks. Here we show that a saprotrophic fungus (Agaricus bisporus) redistributes water from moist (-0.03 MPa) into dry (-9.5 MPa) soil at about 0.3 cm ⋅ min(-1) in single hyphae, resulting in an increase in soil water potential after 72 h. The increase in soil moisture by hydraulic redistribution significantly enhanced carbon mineralization by 2,800% and enzymatic activity by 250-350% in the previously dry soil compartment within 168 h. Our results demonstrate that hydraulic redistribution can partly compensate water deficiency if water is available in other zones of the mycelia network. Hydraulic redistribution is likely one of the mechanisms behind higher drought resistance of soil fungi compared with bacteria. Moreover, hydraulic redistribution by saprotrophic fungi is an underrated pathway of water transport in soils and may lead to a transfer of water to zones of high fungal activity.

Keywords: Carbon Mineralization ; Drought ; Hydraulic Redistribution ; Saprotrophic Fungi ; Agaricus -- Metabolism ; Carbon -- Metabolism ; Minerals -- Metabolism ; Soil -- Chemistry ; Water -- Chemistry

ISSN: 00278424

E-ISSN: 1091-6490

DOI: 10.1073/pnas.1514435112

URL: View this record in MEDLINE/PubMed

Language: English

In: Soil Biology and Biochemistry, Feb, 2014, Vol.69, p.320(8)

Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.soilbio.2013.11.014 Byline: Marianne Schutt, Werner Borken, Oliver Spott, Claus Florian Stange, Egbert Matzner Abstract: Climate models predict warmer winter in temperate regions, but little is known about the temperature sensitivity of soil carbon (C) and nitrogen (N) mineralization at low temperatures. Here, we assess the temperature sensitivities of gross ammonification, gross nitrification, C and net N mineralization of top soil horizons, under a European beech and a Norway spruce temperate forest. We tested the hypotheses that (1) substrate quality affects the temperature sensitivity of C and N mineralization and (2) that temperature sensitivity of C mineralization is higher than of gross ammonification. Soil incubations were conducted at constant temperatures of -4, -1, +2, +5 and +8 [degrees]C. Gross ammonification and nitrification were measured by the.sup.15N pool dilution technique. Temperature sensitivities of C, gross and net N mineralization were calculated using the Arrhenius equation and C mineralization was taken as proxy for substrate quality. Gross ammonification and C mineralization was much larger in the beech than in the spruce soil, while gross nitrification was in the same order of magnitude. Gross ammonification, nitrification and C mineralization almost ceased at -4 [degrees]C, but already increased at -1 [degrees]C. Net ammonification in Oi/Oe horizons was low at -4 and -1 [degrees]C and increased strongly between +2 and +8 [degrees]C. Net nitrification was low in both soils, but increased in the spruce soil at temperatures 〉2 [degrees]C whereas no temperature response occurred in the beech soil. Apparent Q.sub.10 values of gross ammonification and C mineralization in the temperature range of -4 to +8 [degrees]C were in the range of 3-18. Q.sub.10 were lowest in soil horizons of low substrate quality. The ratio of C mineralization to gross ammonification varied between 0.5 and 2.9, suggesting preferential mineralization of N rich organic substrates or rapid turnover of the N pool in microbial biomass. Rising winter temperatures might have substantial effects on net N mineralization, but effects decrease with soil depth, likely due to decreasing substrate quality of soil organic matter. Author Affiliation: (a) Department of Soil Ecology, University of Bayreuth, 95448 Bayreuth, Germany (b) Department of Soil Physics, Helmholtz Center for Environmental Research, UFZ, 06120 Halle/Saale, Germany (c) Bundesanstalt fur Geowissenschaften und Rohstoffe, Fachbereich B2.4 "Boden als Ressource - Stoffeigenschaften und -dynamik", 30655 Hannover, Germany Article History: Received 21 June 2013; Revised 7 November 2013; Accepted 14 November 2013

Keywords: Soil Biology -- Analysis ; Nitrification -- Analysis ; Soil Ecology -- Analysis ; Forest Soils -- Analysis ; Soil Carbon -- Analysis

ISSN: 0038-0717

Source: Cengage Learning, Inc.

Language: English

In: Forest Ecology and Management, Dec 15, 2013, Vol.310, p.110(10)

Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.foreco.2013.08.006 Byline: Michael Goisser, Ulrich Zang, Egbert Matzner, Werner Borken, Karl-Heinz Haberle, Rainer Matyssek Abstract: acents Response of juvenile European beech upon transplant to heterogeneous light and water availability. acents Plant response was examined along the gradients of light and water availability. acents High light acclimation exacerbated productivity decline under drought. acents Progressive acclimation to shade and drought mitigated productivity decline within the study period. Article History: Received 18 April 2013; Revised 4 August 2013; Accepted 5 August 2013

Keywords: Water ; Industrial Productivity

ISSN: 0378-1127

Source: Cengage Learning, Inc.

Language: English

In: Soil Biology and Biochemistry, February 2011, Vol.43(2), pp.333-338

Description: Changes in the soil water regime, predicted as a consequence of global climate change, might influence the N cycle in temperate forest soils. We investigated the effect of decreasing soil water potentials on gross ammonification and nitrification in different soil horizons of a Norway spruce forest and tested the hypotheses that i) gross rates are more sensitive to desiccation in the Oa and EA horizon as compared to the uppermost Oi/Oe horizon and ii) that gross nitrification is more sensitive than gross ammonification. Soil samples were adjusted by air drying to water potentials from about field capacity to around −1.0 MPa, a range that is often observed under field conditions at our site. Gross rates were measured using the N pool dilution technique. To ensure that the addition of solute label to dry soils and the local rewetting does not affect the results by re-mineralization or preferential consumption of N, we compared different extraction and incubation times. T times ranging from 10 to 300 min and incubation times of 48 h and 72 h did not influence the rates of gross ammonification and nitrification. Even small changes of water potential decreased gross ammonification and nitrification in the O horizon. In the EA horizon, gross nitrification was below detection limit and the response of the generally low rates of gross ammonification to decreasing water potentials was minor. In the Oi/Oe horizon gross ammonification and nitrification decreased from 37.5 to 18.3 mg N kg  soil d and from 15.4 to 5.6 mg N kg  soil d when the water potential decreased from field capacity to −0.8 MPa. In the Oa horizon gross ammonification decreased from 7.4 to 4.0 mg N kg  soil d when the water potential reached −0.6 MPa. At such water potential nitrification almost ceased, while in the Oi/Oe horizon nitrification continued at a rather high level. Hence, only in the Oa horizon nitrification was more sensitive to desiccation than ammonification. Extended drought periods that might result from climate change will cause a reduction in gross N turnover rates in forest soils even at moderate levels of soil desiccation. ► Even small changes of water potential decreased gross N turnover rates in the O horizon. ► Only in the Oa horizon gross nitrification was more sensitive to desiccation than ammonification. ► A reduction in gross N turnover rates can be expected in forest soils even at moderate desiccation.

Keywords: 15n Pool Dilution Technique ; Norway Spruce ; Forest Soil ; Agriculture ; Chemistry

ISSN: 0038-0717

E-ISSN: 1879-3428

DOI: 10.1016/j.soilbio.2010.10.020

URL: View record in ScienceDirect (Access to full text may be restricted)

Language: English

In: Forest Ecology and Management, 15 December 2013, Vol.310, pp.110-119

Description: Climate models predict increasing frequency and intensity of summer drought events for Central Europe. In a field experiment, we investigated the response of young beech ( L.) to extreme and repeated summer drought and the modulation of drought response patterns along the natural gradient of light availability at the study site. In autumn 2008, two-year-old, nursery derived beech – as used for forest conversion practices – was planted under a Norway spruce stand primarily opened through winter storm. Precipitation was manipulated in the growing seasons of 2009 through 2011, inducing a pronounced gradient of water availability. Individual drought-stress doses (DSD) and light doses (LD) were calculated for each beech sapling during the three growing seasons. Plant growth, CO -assimilation rate and stomatal conductance were reduced with increasing drought stress, but facilitated by increasing light availability. Progressive acclimation to water and light limitation during the three years of the experiment led to a decreased drought and shade sensitivity of diameter growth. Water-use efficiency, root/shoot ratio and rooting depth, were increased with decreasing water availability. Mean fine root diameter and specific fine root length correlated positively with both DSD and LD. Proceeding low-light acclimation was indicated by progressively increasing specific leaf area and reduced leaf dark-respiration. Present results suggest that nursery-induced high-light acclimation of the beech saplings, exacerbated light limitation upon transplant and hence productivity decline under co-occurring water limitation.

Keywords: European Beech ; Drought ; Light ; Restoration ; Acclimation ; Forestry ; Biology

ISSN: 0378-1127

E-ISSN: 1872-7042

DOI: 10.1016/j.foreco.2013.08.006

URL: View record in ScienceDirect (Access to full text may be restricted)

Language: English

In: Soil Biology and Biochemistry, December 2016, Vol.103, pp.380-387

Description: Hydraulic redistribution (HR) of water from wet to dry soil compartments by non-differentiated mycelium was recently shown for the saprotrophic fungus . The redistributed water triggered the carbon (C) mineralization in the dry soil. The potential of other saprotrophic fungal species and their mycelia networks for HR in soils is unknown. Here, we tested the potential for HR of the mycelial cord forming species compared it to capillary water transport in a sandy soil and assessed the impact of HR on C mineralization and enzyme activities in mesocosm experiments with dry and wet soil compartments using labeled water ( H) and labeled organic substrate ( C, N). Further, we determined nitrogen (N) translocation between the soil compartments by the mycelium of and . The flow velocity of redistributed water in single hyphae of was about 0.43 cm min which is 1.5–2 times higher than in hyphae of , suggesting that cords enhance fungal HR. The amount of redistributed water was similar to capillary transport in the sterile sandy soil. Despite greater potential for HR, only slightly increased C mineralization and enzyme activity in the dry soil within 7 days. translocated N towards the organic substrate in the dry soil and used it for hyphal growth whereas redistributed N within the mycelial network towards the wet soil. Our results suggest that fungal hyphae have the potential to overcome capillary barriers between dry and wet soil compartments via HR and that the impact of fungal HR on C mineralization and N translocation is related to the foraging strategy and the resource usage of the fungus species.

Keywords: Saprotrophic Fungi ; Hydraulic Redistribution ; Drought ; Carbon Mineralization ; Nitrogen Translocation ; Foraging Strategy ; Agriculture ; Chemistry

ISSN: 0038-0717

E-ISSN: 1879-3428

DOI: 10.1016/j.soilbio.2016.09.009

URL: View record in ScienceDirect (Access to full text may be restricted)

Language: English

In: Soil Biology and Biochemistry, February 2014, Vol.69, pp.320-327

Description: Climate models predict warmer winter in temperate regions, but little is known about the temperature sensitivity of soil carbon (C) and nitrogen (N) mineralization at low temperatures. Here, we assess the temperature sensitivities of gross ammonification, gross nitrification, C and net N mineralization of top soil horizons, under a European beech and a Norway spruce temperate forest. We tested the hypotheses that (1) substrate quality affects the temperature sensitivity of C and N mineralization and (2) that temperature sensitivity of C mineralization is higher than of gross ammonification. Soil incubations were conducted at constant temperatures of −4, −1, +2, +5 and +8 °C. Gross ammonification and nitrification were measured by the N pool dilution technique. Temperature sensitivities of C, gross and net N mineralization were calculated using the Arrhenius equation and C mineralization was taken as proxy for substrate quality. Gross ammonification and C mineralization was much larger in the beech than in the spruce soil, while gross nitrification was in the same order of magnitude. Gross ammonification, nitrification and C mineralization almost ceased at −4 °C, but already increased at −1 °C. Net ammonification in Oi/Oe horizons was low at −4 and −1 °C and increased strongly between +2 and +8 °C. Net nitrification was low in both soils, but increased in the spruce soil at temperatures 〉2 °C whereas no temperature response occurred in the beech soil. Apparent values of gross ammonification and C mineralization in the temperature range of −4 to +8 °C were in the range of 3–18. were lowest in soil horizons of low substrate quality. The ratio of C mineralization to gross ammonification varied between 0.5 and 2.9, suggesting preferential mineralization of N rich organic substrates or rapid turnover of the N pool in microbial biomass. Rising winter temperatures might have substantial effects on net N mineralization, but effects decrease with soil depth, likely due to decreasing substrate quality of soil organic matter.

Keywords: Winter Soil Temperatures ; Gross and Net N Mineralization ; Co2 Production ; Forest Soil ; Q10 ; Substrate Quality ; Substrate Availability ; Agriculture ; Chemistry

ISSN: 0038-0717

E-ISSN: 1879-3428

DOI: 10.1016/j.soilbio.2013.11.014

URL: View record in ScienceDirect (Access to full text may be restricted)

Language: English

In: Soil Biology and Biochemistry, October 2014, Vol.77, pp.315-315

Keywords: Agriculture ; Chemistry

ISSN: 0038-0717

E-ISSN: 1879-3428

DOI: 10.1016/j.soilbio.2014.06.001

Source: ScienceDirect Journals (Elsevier)

URL: View record in ScienceDirect (Access to full text may be restricted)

Language: English

In: Biogeochemistry, 2011, Vol.106(3), pp.461-473

Description: Dissolved organic carbon (DOC) is an important component of the C cycle in forest ecosystems, but dynamics and origin of DOC in throughfall and soil solution are yet poorly understood. In a 2-year study, we analyzed the radiocarbon signature of DOC in throughfall and soil solution beneath the Oa horizon and at 90 cm depth in a Norway spruce forest on a Podzol soil. A two-pool mixing model revealed that throughfall DOC comprised mainly biogenic C, i.e. recently fixed C, from canopy leaching and possibly other sources. The contribution of fossil DOC from atmospheric deposition to throughfall DOC was on average 6% with maxima of 8–11% during the dormant season. In soil solution from the Oa horizon, DO 14 C signature was highly dynamic (range from −8‰ to +103‰), but not correlated with DOC concentration. Radiocarbon signatures suggest that DOC beneath the Oa horizon originated mainly from occluded and mineral associated organic matter fractions of the Oa horizon rather than from the Oi or Oe horizon. Relatively old C was released in the rewetting phase following a drought period in the late summer of 2006. In contrast, the DO 14 C signature indicated the release of younger C throughout the humid year 2007. In soil solutions from 90 cm depth, DO 14 C signatures were also highly dynamic (−127‰ to +3‰) despite constantly low DOC concentrations. Similar to the Oa horizon, the lowest DO 14 C signature at 90 cm depth was found after the rewetting phase in the late summer of 2006. Because of the variation in the DO 14 C signatures at this depth, we conclude that DOC was not equilibrated with the surrounding soil, but also originated from overlaying soil horizons. The dynamics of DO 14 C in throughfall and soil solution suggest that the sources of DOC are highly variable in time. Extended drought periods likely have a strong influence on release and translocation of DOC from relatively old and possibly stabilized soil organic matter fractions. Temporal variations as well as the input of fossil DOC needs to be considered when calibrating DOC models based on DO 14 C signatures.

Keywords: Dissolved organic carbon ; Forest soils ; Norway spruce ; Throughfall ; Radiocarbon ; C

ISSN: 0168-2563

E-ISSN: 1573-515X

DOI: 10.1007/s10533-010-9526-2

URL: View full text in Springer (Subscribers only)

In: Global Change Biology, April 2009, Vol.15(4), pp.781-781

Description: To authenticate to the full-text of this article, please visit this link: http://dx.doi.org/10.1111/j.1365-2486.2009.01893.x Byline: WERNER BORKEN (*), EGBERT MATZNER (*) Author Affiliation: (*)Department of Soil Ecology, University of Bayreuth, 95440 Bayreuth, Germany Article note: Correspondence: Werner Borken, tel. +49 921 555 741, fax +49 921 555 799, e-mail: werner.borken@uni-bayreuth.de

Keywords: Soil Ecology ; Soils;

ISSN: 1354-1013

E-ISSN: 1365-2486

DOI: 10.1111/j.1365-2486.2009.01893.x