Drought Effects on Soil Solution Chemistry at Bavarian Level-II sites

Transkript

1 Drought Effects on Soil Solution Chemistry at Bavarian Level-II sites Freiburg Christoph Schulz, Stephan Raspe, Bernd Schultze; Bavarian State Institue of Forestry

2 Structure 1. data base and methodical aspects (missing values) 2. possible reactions to drought 3. Drought effects on measured concentrations 4. Drought effects on fluxes (measured concentrations and modelled seepage [LWF-BROOK90]) 5. Conclusions

3 Data base - Sampling 22 sites, 5 tree species forest floor : - 6 lysimeters per plot - 2-weekly samples Soil: - 4 suction cups at 4 depth (220) cm - 4-weekly samples Up to 13 years of sampling

4 Data base - Missing values mean Substitution of missing values with (by) the mean_mv_filled yearly median of the layer mg/l Jan. 95 Jan. 96 Jan. 97 Jan. 98 Jan. 99 Jan. 00 Jan. 01 Jan. 02 Jan. 03 Jan. 04 Spruce site Flossenbürg; depth 120 cm; nitrate concentration (mg/l)

5 Possible effects of drought on soil solution Additional dead organic material by dying fine roots, microbial biomass and ground vegetation Increased mineralization due to increased soil temperatures Reduced seepage, transpiration and plant uptake Increased concentrations during and after drought Increased fluxes after rewetting

6 Time series (µmolc/l): FLO forest floor µmolc/l Ca µmolc/l Mg µmolc/l Na µmolc/l K µmolc/l Al µmolc/l Fe µmolc/l Mn µmolc/l H µmolc/l NH4 µmolc/l NO3_µmolc/l SO4_µmolc/l Cl_µmolc/l HCO3_µmolc/l

7 Time series (µmolc/l): EBE forest floor µmolc/l Ca µmolc/l Mg µmolc/l Na µmolc/l K µmolc/l Al µmolc/l Fe µmolc/l Mn µmolc/l H µmolc/l NH4 µmolc/l NO3_µmolc/l SO4_µmolc/l Cl_µmolc/l HCO3_µmolc/l

8 Time series (µmolc/l): ALT forest floor µmolc/l Ca µmolc/l Mg µmolc/l Na µmolc/l K µmolc/l Al µmolc/l Fe µmolc/l Mn µmolc/l H µmolc/l NH4 µmolc/l NO3_µmolc/l SO4_µmolc/l Cl_µmolc/l HCO3_µmolc/l

9 Time series WUE 30 cm depth µmolc/l Ca µmolc/l Mg µmolc/l Na µmolc/l K µmolc/l Al µmolc/l Fe µmolc/l Mn µmolc/l H µmolc/l NH4 µmolc/l NO3_µmolc/l SO4_µmolc/l Cl_µmolc/l HCO3_µmolc/l

10 Time series AOE 30 cm depth µmolc/l Ca µmolc/l Mg µmolc/l Na µmolc/l K µmolc/l Al µmolc/l Fe µmolc/l Mn µmolc/l H µmolc/l NH4 µmolc/l NO3_µmolc/l SO4_µmolc/l Cl_µmolc/l HCO3_µmolc/l

11 NO 3- concentration at spruce site Goldkronach throughfall humus 20 cm 40 cm 70 cm 120 cm 20 mg/l Jan. 96 Jan. 97 Jan. 98 Jan. 99 Jan. 00 Jan. 01 Jan. 02 Jan. 03 Jan. 04

12 NO 3- concentration at beech site Bad Brückenau throughfall humus 20 cm 40 cm 60 cm 20 mg/l Jan. 98 Jan. 99 Jan. 00 Jan. 01 Jan. 02 Jan. 03 Jan. 04

13 NO 3- concentration (mg/l) in the forest floor: long-term average vs. 7/2003-6/2004 mean 45 oak 40 Mittel beech spruce Mittel_ mg/l pine 5 0 BBR EBR FRE SOG MIT WUE LAN RIE ROT ZUS AOE GOL EBE FLO KRE SON ROK DIN BOD ALT PEG

14 NO 3- concentration (mg/l) of the upper soil layer: long-term average vs. 7/2003-6/2004 mean oak Mittel spruce Mittel_ mg/l beech 10 5 pine 0 BBR EBR SOG MIT FRE LAN WUE RIE ROT ZUS AOE GOL EBE FLO KRE SON ROK ALT DIN PEG BOD

15 NO 3- concentration (mg/l) of the subsoil: long-term average vs. 7/2003-6/2004 mean oak Mittel Mittel_0304 mg/l beech spruce pine BBR SOG EBR MIT FRE LAN RIE WUE ROT ZUS AOE FLO EBE GOL SON KRE ROK ALT BOD DIN PEG

16 Deduction of element fluxes Forest floor: concentration of twoweekly samples and two-weekly modelled seepage sums (LWF- BROOK90) Mineral soil: concentration of 4- weekly samples and four-weekly modelled seepage sums (suction cups with one week of vacuum pressure)

17 Time series NO 3- -N kg/ha AOE throughfall humus 30 cm 60 cm 90 cm 120 cm 1 kg/ha Jan. 93 Jan. 94 Jan. 95 Jan. 96 Jan. 97 Jan. 98 Jan. 99 Jan. 00 Jan. 01 Jan. 02 Jan. 03 Jan. 04

18 Time series NO 3- -N kg/ha DIN throughfall humus 30 cm 60 cm 120 cm 0,5 kg/ha Jan. 92 Jan. 93 Jan. 94 Jan. 95 Jan. 96 Jan. 97 Jan. 98 Jan. 99 Jan. 00 Jan. 01 Jan. 02 Jan. 03 Jan. 04

19 Time series NO 3- -N kg/ha BBR throughfall humus 20 cm 40 cm 60 cm 2 kg/ha Jan. 98 Jan. 99 Jan. 00 Jan. 01 Jan. 02 Jan. 03 Jan. 04

20 12 10 beech NO 3- -N-fluxes in forest floor: sums of 1. and 2. quarter long-term average vs spruce Fracht_Q12 Fracht04_Q12 8 oak kg/ha pine 0 BBR SOG MIT EBR FRE WUE LAN RIE ROT GOL KRE SON AOE EBE FLO ZUS ROK ALT DIN PEG BOD

21 NO 3- -N-fluxes in upper soil layer: sums of 1. and 2. quarter long-term average vs oak spruce Fracht_Q12 Fracht04_Q12 14 kg/ha beech pine 0 BBR EBR SOG MIT FRE LAN WUE ROT RIE GOL SON AOE KRE ZUS EBE FLO ROK ALT PEG DIN BOD

22 beech NO 3- -N-fluxes deeper soil layer: sums of 1. and 2. quarter long-term average vs Fracht_Q12 Fracht04_Q12 kg/ha 8 6 oak spruce 4 2 pine 0 BBR SOG MIT EBR FRE LAN ROT RIE WUE GOL SON FLO AOE EBE KRE ZUS ROK ALT BOD PEG DIN

23 Conclusions Increased concentrations during and after drought Increased fluxes after drought No leaching till June, 2004 Spruce: reactions in all layers Pine: forest floor remains as a sink Oak and beech: indifferent reactions

24 Outlook Linking element concentrations and fluxes with soil temperatures and soil moisture Linking different fluxes (water, litter, uptake, leaching) Comparison of soil solution chemistry and tree nutrition