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Forest death and soil degradation in the Jizera Mountains

Forest death and soil degradation in the Jizera Mountains. Katy Boon, Steven Cave, Madeleine Cobb, Chris Lewis & Jonathan Townrow. Introduction. This presentation will cover: A brief geological overview of the area and history of coal burning

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Forest death and soil degradation in the Jizera Mountains

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  1. Forest death and soil degradation in the Jizera Mountains Katy Boon, Steven Cave, Madeleine Cobb, Chris Lewis & Jonathan Townrow

  2. Introduction • This presentation will cover: • A brief geological overview of the area and history of coal burning • Some facts about soil nutrients and plant growth • Acid rain and its effects on local vegetation • River water chemistry in the Jizera Mountains • Our interpretations of how things could be improved

  3. Geological history of the Jizera mountains • Variscan age  340 Ma - Devonian • Composed of 99% granite

  4. History of coal burning for power generation • 1980 - 18 billion tonnes of coal reserves • 23% - black coal • 77% - brown coal/lignite • North Bohemian lignite basin - 160km2 mined

  5. Important reactions • Formation of SO2 and nitrogen oxides: • N2 + O2 2NO NO + 0.5O2 NO2 • 2FeS2 + 5.5 O2  Fe2 O3 + 4SO2 • Formation of acids: • SO2 + OH + O2  H2SO4 • NOx + sunlight + OH  HNO3

  6. History of coal burning 2 • 1860’s - production started • 1948 - SO2 emissions 2nd worst in the world • 1989 - productivity declined

  7. History of forest decay in the Jizera mountains • The original forest had a multi-species tree cover. 17th century exploitation of the forest for fuel and construction material led to replacement with a near monoculture of Spruce • 1950’s : The new communist regimes emphasis on coal mining, ore smelting and power generation industries led to an ever-increasing level of atmospheric SO2 emissions until the late 1980’s. • 1970’s Tree damage and forest decay began to be noticed, • 1980’s Forest decay now advanced with trees dying in large numbers and at elevations < 1000m and on South-East slopes.

  8. Plant Nutrients • Ca2+ : Al3+ has a much higher affinity for negatively charged surfaces than Ca2+ leading to displacement and consequent loss of Ca2+ when [Al3+ ] is high, i.e. when pH is low. • Mg2+: Important for photosynthesis as it is a vital component of chlorophyll. Mg2+ is also stripped from soil by high [Al3+ ] Mg2+ deficiency leads to yellowing of needles, metabolic stress and ultimately plant death. • Phosphate is also locked up by high [Al3+ ] PO42- is a major plant nutrient and lack of PO42- is a control on vegetative growth.

  9. Plant Nutrients 2 • Lack of clay minerals due to low pH preventing their formation in the rock weathering horizons. Al(OH)3 is formed in preference to sheet silicates (clays). Al(OH)3 has no cation exchange capacity and little water retention, so Al(OH)3 rich soils have very low fertility. • Low pH leads to stressed, stunted trees susceptible to secondary damage by acid rain, frost, wind, and pests.

  10. Composition of the parent rock • Geology of Jizera Mountains is granitic in nature • Geology directly affects soil formation and structure • Weathering of bedrock provides plant nutrients • KAl3Si3O10(OH)2 + H+ + 1.5H2O  K+ + 1.5Al2Si2O5(OH)4

  11. Mineral composition of Jizera Mountain granites

  12. Composition of alteration minerals in 2 soil profiles • 2 main soil profiles in Jizera Mountains • C horizon - Few alteration minerals • B2 horizon - Chlorite and Kaolinite • B1 horizon - Kaolinite and Al-Fe hydroxides • A horizon - No primary minerals except quartz, lots of alteration minerals

  13. Soil composition and acid rain • Little dissolution of Quartz • Si02 + 2H2O  H4SiO4 • Al3+ + 3H2O  Al(OH)3 + 3H+ • 2Al(OH)3 + H4SiO4  Al2SiO5 (OH)2 + 3H2O + 2H+ • 2Al2SiO5 (OH)2 + 0.5Mg2+ + 0.5Na+  Na0.5Mg 0.5Al 1.5Si4O10 (OH)2 + 3H2O + 0.5Al3+

  14. Chemistry of the Jizera Mountain Rivers • Seasonal changes in: • pH -Ranges between 4 and 6. • minimum of 2 • Al3+ - Acid leaching • maximum of 10,000 ppm • SO42- - gradual decline since 90’s • Others - major water-borne cations, anions and heavy metals

  15. Drinking water in the Vodni nádrž souš dam • Al3+ was being leached from basin • Lime added in the Spring of ’96 • Problems • Health and Aluminium

  16. Jizera vs Ore Mountains • Comparisons: • Similar causes of forest decay • Majority of pollution from Germany and Poland • Similar chemical composition of bedrock

  17. Jizera vs Ore Mountains 2 • Contrasts: • Ore Mountains composed of crystalline rock with mica schists and granitic intrusions. • Ore Mountain’s forest decayed before the Jizera Mountain’s forest due to acidic air composition and relief.

  18. Interpretations and Conclusion • Further environmental legislation required • Re-establishment of forest using acid resistant trees • Lime addition and sludge removal in dam • Potential addition of clay minerals to soil • However some environmental recovery is already evident.

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