Casey McCabe Global Change: Biome Perspective

(Illustration by Nicolle Rager Fuller, National Science Foundation.)

 Carbon sink through primary production  Stores less than boreal and tropical  51% in living biomass  37% in dead wood, litter and soil  Important for regional carbon budgets (Bonan 2008, Pan et al. 2011)

 Contribution to global water cycle and cloud formation  Rates vary across forest types  Forests and crops have higher evaporative cooling than grasslands  Forests have l0w albedo compared to grassland/crops  Land use change in past converted large amount of temperate forest to cropland  Highly managed (Bonan 2008, Jackson et al. 2008, Peters et al. 2013)

Physicochemical Changes Indirect Effects & Feedbacks Megadisturbance

(Pautasso et al. 2012)

Temperature Precipitation CO IPCC Report

 Increased evaporation  Biological effects  Changes in phenology  Range shifts  Increased rain vs. snow and snow melt  Heat stress  Changes in growth rate ▪ Increases and decreases (van Mantgem 2009, Keenan et al. 2014)

 Very variable according to region  Increases in eastern U.S., northern Europe, southeast Asia  Decreases in western U.S., southern Europe, northeast Asia, and eastern Australia  Some areas with increased drought or flooding  Flooding can increase or reduce nutrient levels  Drought can cause tree death and increase susceptibility to pests, pathogens, and fire (2013 IPCC Report, Bentz et al. 2010, Millar and Stephenson 2015)

 Atmospheric CO 2 is increasing  Positive for plant growth and water-use efficiency ▪ Response may be limited by water and nutrients (Silva and Anand 2013) 2013 IPCC Report

(Bonan 2008)

 Temp =  Evaporation =  Evaporative Cooling  Transpiration  Drought  Temp =  Snow =  Yearly Soil Moisture  CO 2 =  Transpiration =  Drought Tolerance

 Temp =  Photosynthesis =  Carbon Sink  CO 2 =  Photosynthesis =  Carbon Sink  Water =  Photosynthesis =  Carbon Sink

(Keenan et al. 2014)

(Millar and Stephenson 2015)

 Baseline mortality of trees is increasing  Dead trees release large amounts of carbon  Old-growth forests store more carbon (van Mantgem et al. 2009)

 Overall, increase in large disturbances across the globe related to global change forcings  More intense droughts, fires, biotic outbreaks, and heat waves (Dale et al. 2001, Millar and Stephenson 2015)

 Increasing due to temperature increase  20.4 million hectares of forest in the US impacted by biotic forcing (10 Massachusetts) annually  The most expensive disturbances for humans  Magnitude of disturbance can equal or surpass that of direct climate forcings ( Bentz et al. 2010)

(Flower and Gonzalez-Meler 2015)

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