Climate change and land-use interactions affect aquatic ecosystems

Transcription

1 Climate change and land-use interactions affect aquatic ecosystems FAFU Dr. John Richardson courses.forestry.ubc.ca/frst386/

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3 Rivers in some of the world s most populous regions are losing water,... "The distribution of the world's fresh water, already an important topic," says Cliff Jacobs of NSF's Division of Atmospheric Sciences, "will occupy front and center stage for years to come in developing adaptation strategies to a changing climate. Of rivers examined, more than 70% were decreasing (period 1948 to 2004) Including: Yellow River (China), Ganges (India), Niger (west Africa), Colorado (SW USA) Rivers that were increasing were largely northern rivers, increased by glacier melt Appear to be related to climate change (consistent with all predictions, but of course there is no way to test this directly) NSF National Science Foundation (USA)

4 Outline Predictions about climate Consequences from different aspects of climate change Responses of aquatic systems photo: courtesy Dr. Mark Wipfli, U of Alaska

5 Surface water is ~0.009% of total Source: US Geological Service (USGS)

6 Change in annual average surface air temperature from to from HadCM2 IS92a Hadley Centre for Climate Prediction and Research, the Met. Office, UK

7 Change in June-July-August average surface air temperature from to from HadCM2 IS92a Hadley Centre for Climate Prediction and Research, UK

8 Change in annual average precipitation from to from HadCM2 IS92a Hadley Centre for Climate Prediction and Research, UK

9 Change in June-July-August average precipitation from to from HadCM2 IS92a Hadley Centre for Climate Prediction and Research, UK

10 Change in annual average soil moisture content from to from HadCM2 IS92a Hadley Centre for Climate Prediction and Research, UK

11 Change in June-July-August average soil moisture content from to from HadCM2 IS92a Biggest effect on aquatic resources will likely be in summer Hadley Centre for Climate Prediction and Research, UK

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13 Predicted change in global river flow between present day and the late 21st century for SRES emissions scenario A1B Hadley Centre for Climate Prediction and Research, UK

14 Potential impacts on: Flows (averages, peaks, lows) Timing of flows Temperatures Water quality (ph, nutrients, etc.) Quality of organic matter Timing of life cycle events 20 th century was the wettest century in the past 1000 years!

15 Interaction of vegetation in H 2 O cycle Transpiration Evaporation stomatal conductance transpiration soil moisture & runoff ~98% of water taken up by roots is lost by transpiration through leaf stomata e.g. 15 m high Silver Maple (Acer saccharinum) can loose 220 litres water per hour through transpiration Hadley Centre for Climate Prediction and Research, UK

16 Stomatal conductance (m/s) Plant response to [CO 2 ] physiological forcing stomatal conductance [CO 2 ] stomatal conductance Precipitation Transpiration Surface evaporation CO 2 concentration inside leaf (ppmv) Surface runoff Infiltration Subsurface runoff Hadley Centre for Climate Prediction and Research, UK

17 Projected global average river flow with & without CO 2 effect on plants business-as-usual scenario Hadley Centre for Climate Prediction and Research, UK

18 Projected changes in river flow with & without CO 2 effects on plants average minus Hadley Centre for Climate Prediction and Research, UK

19 Some predicted consequences of climate change for aquatic systems Summers: warmer temperatures, less rainfall, & higher evapotranspiration less water for aquatic environments (unless reduction in evapotranspiration is sufficient due to increased CO 2 ) Winters: warmer winters mean less storage as snow, so less available during summer Headwater streams will be most impacted by changes (and made worse by water extraction from groundwater, i.e., wells)

20 Some consequences of climate change for aquatic systems More dams and greater extraction less water in lakes, reservoirs and rivers Warmer water and higher concentrations of contaminants The minimal water flows, and not the averages, are the impacts that are most difficult to plan for, and the most damaging for aquatic ecosystems

21 Carnation Creek, BC

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23 Water for Life United Nations International Decade for Action Overexploitation Water pollution Flow modification Habitat degradation Species invasion Dudgeon, D. et al Freshwater biodiversity: importance, threats, status and conservation challenges. Biological Reviews 81:

24 World Resources Institute

25 Threat to biodiversity Human water security threat Vörösmarty CJ et al Global threats to human water security and river biodiversity. Nature 467:

26 Human water security threat Low High Threat to biodiversity Low High Vörösmarty CJ et al Global threats to human water security and river biodiversity. Nature 467:

27 Threats Increasing need for power more dams?

28 Headline Water crisis closes Tofino businesses Resort town is forced to ration drinking water, turn away visitors Vancouver Sun, 30 August 2006

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32 Pacific Ocean Canada km Prairies Rocky Mountains Using up fossil water Schindler, DW & WF Donahue An impending water crisis in Canada s western prairie provinces. Proceedings of the National Academy of Sciences 103:

33 Complex outcomes! + 3 C warming year-round + or Three-spined Sticklebacks Ambient or increased nutrients (N, P) Greig HS, Kratina P, Thompson PL, Palen WJ, Richardson JS & Shurin JB Warming, eutrophication, and predator loss amplify subsidies between aquatic and terrestrial ecosystems. Global Change Biology 18:

34 control Hogg I.D. & Williams D.D Response of stream invertebrates to a global-warming thermal regime: An ecosystem-level manipulation. Ecology 77:

35 Hogg I.D. & Williams D.D Response of stream invertebrates to a global-warming thermal regime: An ecosystem-level manipulation. Ecology 77:

36 Emergence timing of adults of the caddisfly Lepidostoma vernale Adult sizes of Nemoura trispinosa (Plecoptera stoneflies) Hogg I.D. & Williams D.D Response of stream invertebrates to a global-warming thermal regime: An ecosystem-level manipulation. Ecology 77:

37 Biovolume (mm 3 /cm 2 x 10 3 ) Chl a (µg/cm 2 ) 1.5 p = Ambient Elevated p < DOC from poplar leaves grown under ambient CO 2 levels, or 2x ambient (720 ppm) Sampling day DOC from leaves grown under elevated [CO 2 ] had molecules that were harder to break down, and therefore contributed less to biofilm (periphyton) development Kominoski, J.S. et al Elevated CO 2 alters leaf-litter-derived dissolved organic carbon: effects on stream periphyton and crayfish feeding preference. Journal of the North American Benthological Society 26:

38 Time (s) Ambient Elevated p < Crayfish Number Crayfish preferred periphyton (biofilm) produced with ambient DOC (from poplar leaves) over DOC from leaves grown at 2X CO 2 concentrations Kominoski, J.S. et al Elevated CO 2 alters leaf-litter-derived dissolved organic carbon: effects on stream periphyton and crayfish feeding preference. Journal of the North American Benthological Society 26:

39 Hari, R.E. et al Consequences of climatic change for water temperature and brown trout populations in Alpine rivers and streams. Global Change Biology 12:

40 North American Water and Power Alliance (NAWAPA) Ralph M. Parsons Company, California Perhaps increased trade in virtual water instead For additional reading, see Nature 20 March 2008

41 Summary Many dimensions to changes in climate: temperature, rainfall, CO 2, food quality, less storage as snow, seasonality, Some consequences: higher peak flows, lower summer flows, warmer summer temperatures A great deal of uncertainty, however, all predictions are for change, and most changes will be difficult to deal with These changes will result in more and more emphasis on forest management to protect water yield, habitat quality, temperatures, and water quality