Forest Ecology Lecture 21

1. Forest Ecology Lecture 21 Global Change and Forest Ecology

2. I. Greenhouse Gases and Climate Change • Greenhouse gas concept

3. II. Past, Current and Future Climate ? a. evidence for present-day climate change • Air temperature records • ice records (lakes, glaciers, permafrost) • long-term AVHRR records • Bird migration data • Grave digging records

4. II. Past, Current and Future Climate ? a. past climate: Climate has never been constant

7. Ice records: Clues to climate Warming The retreat of alpine and arctic glaciers is well documented (see photos).Other scientists have shown that ice-on is occurring later in the winter and “ice-off” is occurring earlier in spring.Permafrost depth (distance from soil surface to top of permafrost) is increasing and permafrost is completely disappearing in some regions

9. Phenology of high latitude forests appear to be changing: earlier leaf out • Analysis of historical NDVI calculated from AVHRR data shows that high latitude forest are greening up earlier (approx. 10-14 days over the last decade)

10. II. Past, Current and Future Climate ? c. future climate change predictions:temperature A global average of 2°C increase from 1990 to 2100 (representing a 33% decrease in projected temperature in 1990) Temperature increase will range from 1 to 3.5 °C depending on model output used. All global circulation models agree that temperature increase will not be uniform: greatest in high latitude biomes (arctic tundra and boreal forest) and smallest in low latitudes (tropical forest). Greater increases in winter temperatures than summer temperatures Greater increases in temperature in continental regions than coastal regions Precipitation is a BIG unknown, as well as relative humidity, which affects what else????

11. I. Greenhouse Gases (GHG) and Climate Change • greenhouse gases (CO2, NOx, CH4, CFC’s) GHG differ from one another based on: • Rate and source of emission • Effectiveness as a GHG • Longevity in the atmosphere

12. FAQ 2.1, Figure 1

14. GHG characteristics

16. II. Past, Current and Future Climate ? c. future climate change predictions:precipitation Global circulation models agree less on general precipitation patterns

17. II. Past, Current and Future Climate ? c. future climate change predictions:sea level Global circulation models predictions differ with those predicting greater warming also predicting higher rise in sea level. Global sea level has increased 10-25 cm over the past 100 years Most models predict a 50 cm rise in sea level during the next century ( a downward estimate of 25 %). The rising temperatures are likely to cause the melting of at least half the Arctic sea ice by the end of the century. A significant portion of the Greenland ice sheet—which contains enough water to raise the worldwide sea level by about 23 feet. The IPCC's 2001 report projects that sea level could rise between 4 and 35 inches (10 to 89cm) by century's end - 00 million people live within 3 feet (1 meter) of mean sea level.

18. III. GHG Responsible for Climate Change • global carbon budget -

19. III. GHG Responsible for Climate Change Sources CH4 (1012 gCH4/yr) Natural wetlands 115 Open freshwater 5 termites 40 Animals 80 Oceans 10 Anthropogenic Rice paddies 110 Biomass burning 55 Landfills 40 Coal mining 35 Natural gas 45 Methane hydrate 5 • global CH4 budget – natural and anthropogenic forcing factors

20. III. GHG Responsible for Climate Change c. global NOx budget - natural and anthropogenic forcing factors Sources N2O 1012 gN/yr) Natural Oceans 2.0 Tropical soils 3.7 Other soils 2.0 Anthropogenic Agric. Fertilizer 0.7 Cultivation 0.7 Biomass burning 2.0 Fossil fuels 0.0

21. III. GHG Responsible for Climate Change d. global CFC budget - anthropogenic forcing factors 100% anthropogenic !!!!

23. IV. Potential Feedbacks: Terrestrial Biosphere and the Atmosphere Interactions • CO2 fertilization - how will elevated CO2 affect NPP and NEP?

24. Consequences of Climate Change on terrestrial ecosystems - elevated CO2

25. Free Air CO2 Exchange (FACE) Sites

26. Effects of elevated CO2 on tree growth Interactive effects of elevated CO2 & ozone (O3) on tree growth DeLucia et al. 1999 Loblolly pine - 21% Sweetgum - 25% Kruger, unpublished data Norby et al. 2002

27. Effects of Elevated CO2: General Conclusions • In most natural systems, the effects of elevated CO2 on carbon uptake are modest, and short-lived. Why???? • Increased atmospheric CO2 concentration does appear to result in sustained increased carbon uptake in water limited ecosystems and fertile (agriculture, tidal marshes) ecosystems. Why??? • Beneficial effects of elevated atmospheric CO2 concentration on carbon uptake by terrestrial ecosystems can also be limited by the adverse effects of atmospheric pollutants

28. IV. Potential Feedbacks: Terrestrial Biosphere and the Atmosphere Interactions d. Climate warming - how will elevated CO2 driven temperature increases affect NPP and NEP?

29. Boreal Forest Warming Experiment: A case study

30. Experimental Design of the Warming Study Treatment nomenclature: Heated Inside Chamber (HI), Heated Outside Chamber (HO) Control Inside Chamber (CI), Control Outside Chamber (CO)

31. Summary of System Performance H = Heated Plot; HI=Heated, Inside Chamber C = Control Plot; CO= Control, Outside Chamber

33. Present day Future Conceptual Model of Effect of Warming on Respiration, Assuming a Q10 Respiration Temperature

34. ilh June IL June ilh July il July ilh Aug. il Aug. ilh Sept. il Sept. ilh Oct. il Oct. Comparison of monthly soil surface CO2 flux vs. soil temperature for the control and warmed plots Soil respiration 10 9 8 Control 7 -1 6 5 4 Heated 3 2 1 1 0 0 2 4 6 8 10 12 14 16 18 20 Soil temperature (°C) at 10 cm

35. 1995 1996 1997 1998 1999

36. 1998 1995 1989 1981 50 km - Disturbances are an important component of any forest ecosystem - Disturbances have no effect on the C budget if the system is in steady state Climate Warming, Wildfire, & the C Cycle Fire frequency and extent has increased 270% in recent decades In Saskatchewan and Manitoba

37. IV. Potential Feedbacks: Terrestrial Biosphere and the Atmosphere Interactions b. climate warming – how will warming affect C and Water Cycle?

40. Projected agriculture commodity prices and quantity trends for a future climate based on two GCM simulations

41. Projected percent changes in irrigated crop water use requirements and supply based on two GCM simulations

42. IV. Potential Feedbacks: Terrestrial Biosphere and the Atmosphere Interactions c. How will global change affect vegetation distribution

43. Consequences of Climate Change on Northern Latitude Forests - species composition 14,000 years ago 11,000 years ago Present

44. FIA-current model-current GCM-model prediction GCM-model predicted shifts Sugar Maple

45. FIA-current model-current GCM-model prediction GCM-model predicted shifts Paper Birch

46. IV. Potential Feedbacks: Terrestrial Biosphere and the Atmosphere Interactions c. How will global change affect vegetation distribution There are huge uncertainties surrounding these types of analyses, such as: • Migration routes and rates • Inadequate soil development • Physical barriers (mountains, rivers, land use, etc.) • Disruption of critical symbiotic relationships

47. V. Mitigation Options to Offset Rising Atmospheric Greenhouse Gas Concentrations • afforestation and reforestation • others

48. C Sequestration Afforestation Prairie restoration Gower and Barger 2002 Brye, Gower, & Norman 2002 • Carbon accumulation rates in the soil ranged from 0 to 0.65 tc/ha/yr for forest plantations established on marginal agriculture land. Most of the accumulation was in the forest floor. C accumulation rates in vegetation ranged from0.5 to 3.3 tC/ha/hr. • The 25-year-old “restored” prairie at Goose Pond, adjacent to corn agroecosystems, showed no C accumulation, although the C loss rates were lower than for the agroecosystems.

49. Wisconsin area

50. Comparison of CO2 emissions from generation of electricity for different geographic regions in the United States - why the difference??