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Nutrient Regeneration

FIELD BIOLOGY & METHODOLOGY Fall 2013 Althoff. Lecture 08. Nutrient Regeneration. Cycling & Nutrient Regeneration.

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Nutrient Regeneration

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  1. FIELD BIOLOGY & METHODOLOGYFall 2013 Althoff Lecture 08 Nutrient Regeneration

  2. Cycling & Nutrient Regeneration • Elements cycle through ecosystems along paths dictated by their ______________… a) which determine their chemical reactions b) which determine their biological reactions • Processes of nutrient regeneration is different in terrestrial vs. aquatic systems

  3. Terrestrial System: Nutrient • Nutrients primarily regenerated in the ______ • New nutrients source is formation of soil through weathering of bedrock…in the deep layers of the soil. • This weathering process is relatively ______, especially in regard to annual uptake of nutrients by vegetation…so where is the bulk of the nutrients made available to plants coming from????

  4. Root penetration and development Organic horizon Horizon generally lacking significant organic matter _________ ___________ Bedrock

  5. Hubbard Brook Forest –NH study • 1960s and 1970s • Evaluated an entire watershed • Examined “inputs” and “outputs” Rain gauges used To measure nutrient inputs

  6. A watershed

  7. Hubbard Brook study --note the sharp decline in __ in red spruce trees following lowest pH values in precipitation & stream water…and in stream --Ca leached from the watershed --Ca critical to tree growth

  8. Terrestrial System: Nutrient • Weathering estimates: ~10% of what plants annually take up provided by weathering process in soil • The bulk (estimated ~90%) nutrients taken up by plants annually are “regenerated” by the breakdown of detritus and small organic molecules within the soil profile

  9. Detritus • DEFINED: Freshly _______________organic matter • Almost everywhere in terrestrial habitats: a) parts of plants (dead) not consumed by herbivores b) animal excreta (droppings) • This “layer” is the location of the breakdown that results in nutrients transforming into forms that can be reused by plants

  10. “Processing” detritus to regenerate nutrients • Breakdown of this “___________” on the forest floor, for example, occurs in 4 ways: 1) _________ of soluble minerals by ______ 2) consumption by _______________________________ (millipedes, earthworms, wood lice, and other invertebrates) 3) ___________ of woody components of leaves by ________ 4) _____________ of about ‘anything’ by ___________

  11. Leaves of different species …… • Decompose at _________ rates. • Example of first year leaf decomposition rates in eastern Tennessee forests: Weight loss of decaying leaves for…. mulberry was 64% oak was 39% sugar maple was 32% beech was 21% • Decomposition rates also affected by N, P, and other nutrient concentrations required by _______ and ______ for their own growth

  12. Temperate vs. Tropical Ecosystems • Climate effects weathering • Climate effects soil properties • Climate effects the rate of decomposition

  13. Tropical Ecosystems • Deeply weathered, low in clay content means soils have poor ability to _______________ (low cation exchange capacity) • Warmer temperatures year-round means decomposition _______________ • Higher productivity associated with ________ ________________ means nutrient uptake by plants results in retention of nutrients in the _____________.

  14. Tropical forest: turnover is __? • Compared to temperate forest, more nutrients are tied up in living biomass, above ground • If we harvest rainforest, therefore, what are the consequences?

  15. Soil Fertility is Jeopardized Carbon Content of Soil (soil organic matter) Canada Brazil Venezuelan prairieshrub for. rain forest Carbon 8.8 kg m-1 3.4 kg m -1 5.1 kg m -1 Activity farming farming farming Years 65 6 3 Decline 1%/yr 9%/yr 29%

  16. Conclusions • Cultivatedtemperate zone soils retain organic matter _____ longer than tropical soils • Temperate soils provide more _________ store of mineral nutrients that can be released by slower rate of decomposition

  17. Review: • Distribution of mineral nutrients Ricklefs (1995) (Table 8.1, page 168 – handout) compare: ash and oak (temperate) vs. tropical “________________________” • __________ (“well-nourished”) vs. ___________ (“poorly-nourished”) standing crop & fluxes Ricklefs(1995) (Table 8.2 – handout)

  18. Aquatic Systems • Nutrients regenerated __________ • Mostly regenerated in ______ layers of water and sediment • Algae and aquatic plants assimilate nutrients from the water column in the uppermost (sunlight) zones….far removed from sediments at bottom [contrast to plants & soils] • More ___________ conditions in aquatic sediments than in upper horizons of terrestrial soils

  19. Aquatic Systems • Thermal stratification hinders vertical mixing in aquatic ecosystems • Layering created largely by influence of solar radiation warming upper zone(s). • _____________ can also influence O2 concentration levels…thus, affecting bacteria respiration rates and the water chemistry

  20. p175,Fig. 8.16 (Ricklef’s 5th edition)

  21. Shaded area time of O2 depletion (________ _________) Also, note time of “mixing”

  22. Phosphorus & Eutrophication • Often scare (limiting) in otherwise high-quality (O2) lakes • Addition of nutrients, particularly P, in sewage and/or runoff & drainage from fertilized agricultural lands can results in nutrient loading…can be negative if BIOLOGICAL OXYGEN DEMAND (BOD) results

  23. BOD (_______________________) • Oxidative breakdown of the detritus by microorganisms zaps water of dissolved oxygen. • Serious problem, especially in winter when photosynthesis rates are low and little oxygen in water column…results in fish kill and other organisms negatively impacted

  24. In summary… • Nutrient regeneration in terrestrial ecosystems takes place in the _____ with nutrients regenerated from leaf litter • Tropical forest soils differ markedly from temperate forest soils when it comes to nutrient __________ and ________________ • Aquatic sediments are ______________ from sites of nutrient uptake by plants and algae…more so than soil-to-plant distances for terrestrial ecosystems

  25. In summary… • Vertical mixing in aquatic systems is inhibited by _____________________ • Nutrient regeneration in aquatic sediments is by _______________ decomposition of organic matter—often in highly anaerobic conditions

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