1 Mon. Tues. Wed. Thurs. Fri. Week of Oct. 13 Week of Oct. 20 Wet, muddy outdoor lab – wear closed-toed shoes Week of Oct. 27 Independent project set-up Class in Library Multimedia Room Get back to us on Lemna experiments if necessary Week of Nov. 3 Forest ecology lab – dress for weather Exam 2 T lab switch?

2 Mistake on exam Key – #15 should be b.

3 Outline for ecosystems Introduction How does energy move through an ecosystem? How does matter move through an ecosystem?

4 All organisms participate in element cycling. Each group will be assigned one of the following element cycles (C, N, P, S). Describe 5 ways that your everyday activities contribute to the element cycles (hint: think about the indirect effects of your activities). In your answer, include 1 process that transforms an element from inorganic to organic form, 1 process that transforms an element from organic form to inorganic form, and 1 non-biological transformation.

5 Carbon cycle Driving a car, smoking a cigarette, burning oil Respiration Growing plants for food Compost pile in back yard Carbon from fossil fuel burning dissolves into ocean and precipitates as limestonec

6 Nitrogen cycle Driving a car Growing plants for food – N fertilizer Eating plants and excreting excess N Planting soybeans and clover Using excess N fertilizer that runs off into streams

7 Sulfur cycle Driving a car Burning coal produces acid rain Eating plants and excreting excess S Planting vegetation Walking on dirt paths rather than sidewalk

8 Phosphorus cycle Growing plants for food – P fertilizer Sedimentation and burial of P in lakes Eating plants and excreting excess P P in sewage discharged to water stimulates algal growth Tilling land for agriculture releases P into air

9 How does matter move through an ecosystem? Nutrient recycling in terrestrial and aquatic ecosystems

10 Nutrient recycling in terrestrial systems - where is it happening?

11 Nutrient recycling in terrestrial systems - new weathering of bedrock provides small amount of nutrients taken up by vegetation each year (~10%) - how do we know that?

12 -mass balance -inputs = outputs -weathering + precipitation =loss in streams measure calculate by difference

13 Figure 8.2

14 Figure 8.3

15 Organic matter decomposition 1.Leaching of soluble compounds by water 2.Consumption by detritus-feeding orgs. -e.g., earthworms, millipedes, etc. 3.Breakdown of rest by fungi and bacteria - how do they decompose? What factors affect rate of decomposition?

16 Effect of rainfall on rate of leaf decomposition

17 Litter/living leaf Soil P/plant P Soil N/plant N %of total org C Tropical Temperate Which column is larger?

18 Land use affects phosphorus retention in a system

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20 Nitrogen fixation can increase nitrogen avail. Litter quality (nitrogen content) of different tree species

21 Mychorrhizae increase nutrient content of plants Fig. 8.7

22 Nutrient recycling in aquatic systems - where is it happening?

23 -sediments not in contact with pelagic zone - most sediments are anaerobic - reactions are slower Pelagic zone

24 Figure 8.12

25 Cool (dense) water Warm (low density) water Water below the thermocline may become depleted of oxygen in summertime Why?

26 Fig. 8.16

27 Low oxygen in facilitates recycling of some nutrients (P and Fe) When oxygen is present, P and Fe combine to form insoluble compounds which remain in the sediments When oxygen is absent, P and Fe are soluble and remain in water – can be mixed up into pelagic zone and taken up by algae

28 Fig. 8.17

29 Which nutrient is most limiting to aquatic systems?? What do I mean by most limiting?

30 P - limitation N-limitation LIS Housatonic Where does P-limitation switch to N-limitation? How will changes in nutrient loading affect species composition and frequency of algal blooms? Goal to decrease N input to LIS by 55% in 15 years

31 Example of using properties of nutrient recycling in aquatic systems to reduce algal blooms in freshwater systems

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33 Thermocline  Fountain  oxygen How could this reduce algal blooms?

34 Nutrient recycling - Terrestrial systems - soil - weathering of rock - decomposition of organic matter - Aquatic systems - sediments and deep water - reactions slow (anaerobic) - decomposition not near uptake