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Litter Decomposition as a Source of Active Phosphates in Spruce and Beech Mountainous Forests Affected by Acidification
Available online at www.sciencedirect.com
ScienceDirect Procedia Earth and Planetary Science 10 (2014) 130 – 132
Geochemistry of the Earth’s Surface meeting, GES-10
Litter decomposition as a source of active phosphates in spruce and beech mountainous forests affected by acidification Václav Tejneckýa*, Naďa Řeřichováa, Monika Bradováa, Karel Němečeka, Hana Šantrůčkováb, Christopher Asha, Ondřej Drábeka a
Department of Soil Science and Soil Protection, Faculty of Agrobiology, Food and Natural Resources, Czech University of Life Sciences Prague, Kamýcká 129, 165 21 Prague 6, Czech Republic b Department of Ecosystem Biology, Faculty of Science, University of South Bohemia, Branišovská 31, 370 05 České Budějovice, Czech Republic
Abstract
In this contribution, results from a short-term litter bag experiment are presented. Beech leaves and spruce needles were placed in polyamide bags, and then inserted between litter and fermentation horizons for the period April to November 2013. Each type of litter was placed under the same corresponding forest type. Three litter bags were sampled each month. Water extractable contents of cations or anions were determined by means of ion chromatography and ICP-OES. Weight loss, pH and total chemical composition of litter were also investigated. We observed a greater release of the majority of water extractable cations and anions from beech litter compared to spruce litter. However, we observed a higher amount of available PO43- from spruce needles in comparison to more nutrient rich beech leaves. We expect that availability of PO43- is controlled mainly by the high amount of major cations (Ca2+ and Mg2+) and probably Al3+. An excess of these cations probably leads to phosphate precipitation under beech forest. In contrast, the production of dissolved ions by spruce litter does not significantly vary during the biologically active period of the year. © 2014 Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license © 2014 The Authors. Published by Elsevier B.V. (http://creativecommons.org/licenses/by-nc-nd/3.0/). Peer-review under responsibility of the Scientific Committee of GES-10. Peer-review under responsibility of the Scientific Committee of GES-10 Keywords: Litter decomposition, phosphate, forest soils, litter bag, beech, spruce
* Corresponding author. Tel.: +420 224 382 759; fax: +420 224 382 756. E-mail address: [email protected]
1878-5220 © 2014 Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/). Peer-review under responsibility of the Scientific Committee of GES-10 doi:10.1016/j.proeps.2014.08.043
Václav Tejnecký et al. / Procedia Earth and Planetary Science 10 (2014) 130 – 132
1. Introduction Litter is an important source of nutrients (e.g. C, N, K, Mg, Ca and P) to soils and has a role in element cycling in the forest ecosystem. The rate of decomposition of litter depends on the chemical quality of the material, availability of energy sources, activities of soil fauna (meso and micro) and the environment condition1. The water soluble/extractable fraction of litter represents an active pool of readily available nutrients in the soil environment to fuel the microbial population2. The aim of this study is to monitor water extractable phosphates during decomposition of beech leaves and spruce needles from spring to late autumn. 2. Material and methods A litter bag experiment was used for the determination of decomposition of spruce needles and beech leaves. New fallen litter (Ln horizons) for the litter bags experiment was sampled quantitatively in the dormant season of 2011 under spruce and beech forest. The experiment was carried out in a mountainous forest region affected by acidification - Jizera Mountains (Czech Republic). Entic and Haplic Podzols under spruce forest and Aluminic Cambisols under beech forest were the prevailing acidic soil type. Soils under spruce forest were more acidic (pH = 3.82±0.29) than beech forest (pH = 4.08±0.27). The sampled locality is described in detail in our previous work3. Litter bags were made from polyamide material with 99 μm mesh size and 50 μm fibre diameter. Bags with 5 g of dry litter were placed between litter (L) and fermentation (F) organic horizons in April 2013. The bags with beech litter were placed under beech forest and spruce litter under spruce forest. Bags were sampled in triplicate every month from May to November 2013. After collection the bags were immediately frozen. Water extracts were made from each defrosted sample (1 g of thawed sample with 30 ml deionised H2O). The suspension was then centrifuged at 4000 rpm for 15 min; finally, extracts were filtrated through a 0.45 µm nylon membrane filter (Cronus Membrane Filter Nylon). In aqueous extracts, the following chemical parameters were determined: pH, main inorganic (Cl-, NO3-, SO42- and PO43-) and organic (lactate, acetate, formate and oxalate) anions by means of ion chromatography (IC, ICS 1600, Dionex) with suppressed conductivity. Cations (Na+, NH4+, K+, Mg2+, Ca2+) were determined by means of IC (ICS 90, Dionex) and the contents of selected elements (e.g. P, Al, Fe and Mn) by inductively coupled plasma-optical emission spectrometer (ICP-OES, DUO iCap 7000, Thermo Scientific). A part of each sample was oven dried (40°C) then homogenized and digested in Teflon vessels with the addition of HNO3 (0,5 g of samples and 5-10 ml 65 % HNO3). In the obtained solution, the contents of selected elements (P, Ca, Mg, K, Al, Fe and Mn) were determined by means of AAS (280 FS, Varin) or ICP-OES (DUO iCap 7000, Thermo Scientific). Quality of digestion and analysis were controlled using standard reference materials (NIST SRM 1575a Pine Needles and NCS DC 73351 Tea). The contents of elements and substances were calculated from dry mass. Moisture and weight loss of litter was also calculated. Stratigraphics XVI.I Centurion was used for statistical analyses. 3. Results Weight loss was observed for both environments during the entire sampling period from May to November 2013. A relatively linear weight loss of the original material was observed for spruce needles. The highest weight loss of leaves was determined in the second sampling period (June) in beech forest. After this period, we observed a relatively linear loss of litter material. pH was higher in beech leaves compared to spruce needles, however, the difference was not statistically significant. Mean moisture was significantly higher for beech litter. Water extractable species were monitored during the experiment period (Fig. 1.). pH of aqueous extract from beech leaf was the highest at the beginning of the experiment (pH = 6.4) and decreased during the experiment. Generally, Ca2+ and Mg2+ were the most abundant cations under both forests. Most ionic species were released from beech litter in comparison to spruce litter. On the contrary, higher amounts of PO43- and NH4+ were observed in spruce litter extract during the experiment (Fig. 1.). In October, a higher amount of “fresh” released K+ from the new litter of beech forest was observed. The phosphates were unavailable and production of all monitored cations were significantly higher than inorganic anions during autumn (S-N). The Influence of other organic anions (fenolic compounds, amino acids etc) is not included in this
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study; however, it seems to account for the missing pool of negative charge. We expect that availability of PO43- is controlled mainly by a high amount of the main cations (Ca2+ and Mg2+) and probably Al3+. The excess of these cations probably leads to phosphate precipitation under beech forest. In contrast, we suppose that this precipitation does not occur in the same scale under spruce forest, as there is no excess of Ca2+ and Mg2+.
Fig. 1. Water extractable species (meq kg-1) of beech (left) and spruce (right) litter during sampling period (May (M) - November (N) 2013), mean from three replicates in each sampling period. LMMOA - sum of determined low molecular mass organic acid (lactic, acetic, formic, oxalic).
Conclusions It can be stated that beech litter is an important source of active nutrients (e.g. K+, Mg2+, Ca2+ and PO43-); however, the phosphates appear in available form only in the spring and up to midsummer (May-August). In contrast, the production of dissolved ions (notably phosphates) by spruce litter does not significantly vary during the biologically active period of the year. Acknowledgements The research was supported by the projects of Czech University of Life Sciences Prague (internal project No. CIGA 21130/1313/3106) and the Ministry of Agriculture of the Czech Republic (project NAZV no. QI112A201). References 1. Fisher, RF, Binkley D. Ecology and management of forest soil. 3rd ed. New York: John Wiley & Sons; 2000. 2. Sanderman J, Amundson R. 8.07 - Biogeochemistry of Decomposition and Detrital Processing. In: Holland HD, Turekian KK, editors. Treatise on Geochemistry. Oxford: Pergamon; 2003. p. 249-316. 3. Tejnecký V, Bradová M., Borůvka L, Němeček K, Šebek O, Nikodem A, Zenáhlíková J, Rejzek J, Drábek O. Profile distribution and temporal changes of sulphate and nitrate contents and related soil properties under beech and spruce forests. Sci Total Environ 2013;442:165-171.
ScienceDirect Procedia Earth and Planetary Science 10 (2014) 130 – 132
Geochemistry of the Earth’s Surface meeting, GES-10
Litter decomposition as a source of active phosphates in spruce and beech mountainous forests affected by acidification Václav Tejneckýa*, Naďa Řeřichováa, Monika Bradováa, Karel Němečeka, Hana Šantrůčkováb, Christopher Asha, Ondřej Drábeka a
Department of Soil Science and Soil Protection, Faculty of Agrobiology, Food and Natural Resources, Czech University of Life Sciences Prague, Kamýcká 129, 165 21 Prague 6, Czech Republic b Department of Ecosystem Biology, Faculty of Science, University of South Bohemia, Branišovská 31, 370 05 České Budějovice, Czech Republic
Abstract
In this contribution, results from a short-term litter bag experiment are presented. Beech leaves and spruce needles were placed in polyamide bags, and then inserted between litter and fermentation horizons for the period April to November 2013. Each type of litter was placed under the same corresponding forest type. Three litter bags were sampled each month. Water extractable contents of cations or anions were determined by means of ion chromatography and ICP-OES. Weight loss, pH and total chemical composition of litter were also investigated. We observed a greater release of the majority of water extractable cations and anions from beech litter compared to spruce litter. However, we observed a higher amount of available PO43- from spruce needles in comparison to more nutrient rich beech leaves. We expect that availability of PO43- is controlled mainly by the high amount of major cations (Ca2+ and Mg2+) and probably Al3+. An excess of these cations probably leads to phosphate precipitation under beech forest. In contrast, the production of dissolved ions by spruce litter does not significantly vary during the biologically active period of the year. © 2014 Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license © 2014 The Authors. Published by Elsevier B.V. (http://creativecommons.org/licenses/by-nc-nd/3.0/). Peer-review under responsibility of the Scientific Committee of GES-10. Peer-review under responsibility of the Scientific Committee of GES-10 Keywords: Litter decomposition, phosphate, forest soils, litter bag, beech, spruce
* Corresponding author. Tel.: +420 224 382 759; fax: +420 224 382 756. E-mail address: [email protected]
1878-5220 © 2014 Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/). Peer-review under responsibility of the Scientific Committee of GES-10 doi:10.1016/j.proeps.2014.08.043
Václav Tejnecký et al. / Procedia Earth and Planetary Science 10 (2014) 130 – 132
1. Introduction Litter is an important source of nutrients (e.g. C, N, K, Mg, Ca and P) to soils and has a role in element cycling in the forest ecosystem. The rate of decomposition of litter depends on the chemical quality of the material, availability of energy sources, activities of soil fauna (meso and micro) and the environment condition1. The water soluble/extractable fraction of litter represents an active pool of readily available nutrients in the soil environment to fuel the microbial population2. The aim of this study is to monitor water extractable phosphates during decomposition of beech leaves and spruce needles from spring to late autumn. 2. Material and methods A litter bag experiment was used for the determination of decomposition of spruce needles and beech leaves. New fallen litter (Ln horizons) for the litter bags experiment was sampled quantitatively in the dormant season of 2011 under spruce and beech forest. The experiment was carried out in a mountainous forest region affected by acidification - Jizera Mountains (Czech Republic). Entic and Haplic Podzols under spruce forest and Aluminic Cambisols under beech forest were the prevailing acidic soil type. Soils under spruce forest were more acidic (pH = 3.82±0.29) than beech forest (pH = 4.08±0.27). The sampled locality is described in detail in our previous work3. Litter bags were made from polyamide material with 99 μm mesh size and 50 μm fibre diameter. Bags with 5 g of dry litter were placed between litter (L) and fermentation (F) organic horizons in April 2013. The bags with beech litter were placed under beech forest and spruce litter under spruce forest. Bags were sampled in triplicate every month from May to November 2013. After collection the bags were immediately frozen. Water extracts were made from each defrosted sample (1 g of thawed sample with 30 ml deionised H2O). The suspension was then centrifuged at 4000 rpm for 15 min; finally, extracts were filtrated through a 0.45 µm nylon membrane filter (Cronus Membrane Filter Nylon). In aqueous extracts, the following chemical parameters were determined: pH, main inorganic (Cl-, NO3-, SO42- and PO43-) and organic (lactate, acetate, formate and oxalate) anions by means of ion chromatography (IC, ICS 1600, Dionex) with suppressed conductivity. Cations (Na+, NH4+, K+, Mg2+, Ca2+) were determined by means of IC (ICS 90, Dionex) and the contents of selected elements (e.g. P, Al, Fe and Mn) by inductively coupled plasma-optical emission spectrometer (ICP-OES, DUO iCap 7000, Thermo Scientific). A part of each sample was oven dried (40°C) then homogenized and digested in Teflon vessels with the addition of HNO3 (0,5 g of samples and 5-10 ml 65 % HNO3). In the obtained solution, the contents of selected elements (P, Ca, Mg, K, Al, Fe and Mn) were determined by means of AAS (280 FS, Varin) or ICP-OES (DUO iCap 7000, Thermo Scientific). Quality of digestion and analysis were controlled using standard reference materials (NIST SRM 1575a Pine Needles and NCS DC 73351 Tea). The contents of elements and substances were calculated from dry mass. Moisture and weight loss of litter was also calculated. Stratigraphics XVI.I Centurion was used for statistical analyses. 3. Results Weight loss was observed for both environments during the entire sampling period from May to November 2013. A relatively linear weight loss of the original material was observed for spruce needles. The highest weight loss of leaves was determined in the second sampling period (June) in beech forest. After this period, we observed a relatively linear loss of litter material. pH was higher in beech leaves compared to spruce needles, however, the difference was not statistically significant. Mean moisture was significantly higher for beech litter. Water extractable species were monitored during the experiment period (Fig. 1.). pH of aqueous extract from beech leaf was the highest at the beginning of the experiment (pH = 6.4) and decreased during the experiment. Generally, Ca2+ and Mg2+ were the most abundant cations under both forests. Most ionic species were released from beech litter in comparison to spruce litter. On the contrary, higher amounts of PO43- and NH4+ were observed in spruce litter extract during the experiment (Fig. 1.). In October, a higher amount of “fresh” released K+ from the new litter of beech forest was observed. The phosphates were unavailable and production of all monitored cations were significantly higher than inorganic anions during autumn (S-N). The Influence of other organic anions (fenolic compounds, amino acids etc) is not included in this
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Václav Tejnecký et al. / Procedia Earth and Planetary Science 10 (2014) 130 – 132
study; however, it seems to account for the missing pool of negative charge. We expect that availability of PO43- is controlled mainly by a high amount of the main cations (Ca2+ and Mg2+) and probably Al3+. The excess of these cations probably leads to phosphate precipitation under beech forest. In contrast, we suppose that this precipitation does not occur in the same scale under spruce forest, as there is no excess of Ca2+ and Mg2+.
Fig. 1. Water extractable species (meq kg-1) of beech (left) and spruce (right) litter during sampling period (May (M) - November (N) 2013), mean from three replicates in each sampling period. LMMOA - sum of determined low molecular mass organic acid (lactic, acetic, formic, oxalic).
Conclusions It can be stated that beech litter is an important source of active nutrients (e.g. K+, Mg2+, Ca2+ and PO43-); however, the phosphates appear in available form only in the spring and up to midsummer (May-August). In contrast, the production of dissolved ions (notably phosphates) by spruce litter does not significantly vary during the biologically active period of the year. Acknowledgements The research was supported by the projects of Czech University of Life Sciences Prague (internal project No. CIGA 21130/1313/3106) and the Ministry of Agriculture of the Czech Republic (project NAZV no. QI112A201). References 1. Fisher, RF, Binkley D. Ecology and management of forest soil. 3rd ed. New York: John Wiley & Sons; 2000. 2. Sanderman J, Amundson R. 8.07 - Biogeochemistry of Decomposition and Detrital Processing. In: Holland HD, Turekian KK, editors. Treatise on Geochemistry. Oxford: Pergamon; 2003. p. 249-316. 3. Tejnecký V, Bradová M., Borůvka L, Němeček K, Šebek O, Nikodem A, Zenáhlíková J, Rejzek J, Drábek O. Profile distribution and temporal changes of sulphate and nitrate contents and related soil properties under beech and spruce forests. Sci Total Environ 2013;442:165-171.