Dr. Sara Via, umd.edu 1/4/2018

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1 The effects of climate change on native plants Evidence: 2016 the hottest year ever Difference from historical average temperatures David Inouye Dr. Sara Via Professor & Climate Extension Specialist UMD, College Park Source: NASA, Climate Central of 15 hottest years all since Current CO 2 level way out of pre-industrial range All you need to know: More CO 2 in the atmosphere slows heat loss CO2 concentration from ice cores obser ved dir ectly Year (AD) 2. Temperature tracks CO 2 Most solar radiation is absorbed by the Earth and warms it Some energy is radiated back into space as infrared (heat) waves Greenhouse gas molecules absorb infrared waves and reflect some heat back to Earth, slowing heat loss *more gas molecules, **slower heat loss ***more warming 3. Temperature NOT correlated with solar radiation or volcanic activity Severe Weather Global warming is contributing to an increased incidence of extreme weather because the environment in which all storms form has changed Warmer ocean = more evaporation more water vapor in air Dr. Kevin Trenberth -warmer air -warmer ocean -more water vapor in air -higher sea level National Center for Atmospheric Research June 2011

2 The NEW NORMAL for Plant Communities The NEW NORMAL for Plant Communities 1. More CO 2 in the air 2. Rising temperatures - warmer winters, longer seasons - more extremely hot days, fewer cool nights - heat waves last longer 3. Increased temperature variability 4. Heavier downpours, more severe weather 5. Increased possibility of drought 6. Salination in coastal areas: rising water table, storm surge Effects of higher CO 2 If only CO 2 changes, plants may grow larger, but.. as CO2 increases and plants produce 2-3x more pollen! Poison ivy growth up 149% at Duke CO 2 site, & oil is more allergenic. (Mohan et al Proc. Nat. Acad. Sci. 103(24): ). Source: National Climate Assessment (2014 Yes: No: Isn t more CO 2 good for plants? Plants use CO 2 in photosynthesis, so more should be good, but As CO 2 rises in the atmosphere, - temperature rises, soil moisture decreases - summer droughts more likely, - photosynthesis drops b/c stomates close to prevent water loss Impacts of Climate Change: Temperature Net effect of increased CO 2 is negative for plants 3/27/ Minimum temperature rising faster than maximum - Fewer cold nights for perennials that need chilling

3 Warmer temperature, earlier blooming Cherries bloom 7 days earlier than in 1980 s Warmer winters & earlier flowering Unexpected cold snap è freezing, flower loss Delphinium barbeyi Lilacs bloom 4 days earlier than in the 1950s Source: David Inouye Native Plants: Shifts in flowering time in just 39 years - 69 native species Rocky Mountains - most species flower earlier, extent variable Climate change in Thoreau s woods - plants may flower at smaller size Fr anks & Weis (2008) J. Evol. Biol Long-term studies crucial Source: David Inou Climate change in Thoreau s woods Native plants flower 11 days earlier now (on average) and invasives flower earlier than natives Thoreau s woods and beyond Warmer winters favor invasives - better overwinter survival - earlier flowering time - competitive advantage over natives by taking space, water &nutrients Thoreau Hosney Primack Willis CG, et al. (2010) Favorable Climate Change Response Explains Non-Native Species' Success in Thoreau's Woods. PLoS ONE 5(1): e8878. doi: /journal.pone

4 Invasive plants in US forests Invasives: Oriental bittersweet (Cleastrus orbiculatus) da. gov/ c ompas s/2 01 6/ 01/ 05/ a-bi g -pi cture -vi ew -of -the-i nv asi ve-pla nt-pr oblem / Range expansion: Oriental bittersweet Effects of warmer winters: animals now future distribution (Business as usual, BAU Deer - more food during winter - healthier populations - higher overwinter survival - increase in # offspring & offspring survival. Deer grazing changes plant communities! -Native plants favored by deer decline, ie Trillium. -Plants deer don t like increase: garlic mustard. Effects of warmer winters on animals Insects - better overwinter survival - earlier appearance - more generations/yr - range expansion multiflora rose

5 Warmer winters: range expansions Hemlock wooly adelgid Warmer winters: range expansion Mountain pine beetle Befor e After Dukes et al (2009) Can. J. For. Res 39:231 MPB now ready to spread to eastern Canada -Crossed the Rockies - Shifted onto Jack Pine Mismatched timing in species interactions Plants and pollinators can respond differently to warming - Asynchrony can cause failure to set seed, lack of food for pollinators - Bad for plants AND pollinators Lodgepole Pine Jack Pine 28 Source: David Inouye Trees killed by MPB & 2012 drought èfire èflooding Impacts of California wildfires on forests Water deficits are increasing 2013 Reuters/Rick Wilking Black Forest, Colorado 12 June 2013 It takes a long time to regrow from seedlings Stevens Rumann et al Ecology Letter s

6 Wildfires can change plant communities Heat stress: - reduces growth rate (less photosynthesis) - increases water loss - can impact every stage California: Burned plots more likely to change from northern temperate to southern xeric very hard on forest trees - reduced growth - stress - large trees die first Pathogens feast on stressed trees Water: too little or too much Armillaria root rot And heat stressed trees grow more slowly Dukes et al (2009) Can. J. For. Res 39:231 May stunt or kill plants, increase disease, bring in toxins, change plant community if frequent Climate Resilience Toolkit: Climate Change Atlas Forest Composition will change under BAU NOW 2100 and don t for get the invasive species!

7 Chicago Botanical Garden Which tree species will survive in Chicago under climate change? -20% of species in study won t survive expected 2050 conditions - 80% gone in 2080 Now Climate-friendly landscaping Reduce Lawn!! - 42 million acres of lawn in US - high inputs, runoff - mowing causes emissions - water hungry Autumn Gold Ginkgo: YES American Linden: NO 2080 Climate-friendly landscaping Control erosion -Garden design, raingardens Carbon sequestration in the home landscape - Plant as many trees as practical - Emphasize perennial plants - Build healthy soil Native plants (Bay-Wise) - more drought resistant The Climate-conscious Gardener, 2010 You may not run the world, but you can control your part of it Thank you! me anytime with questions: Dr. Sara Via Professor & Climate Extension Specialist svia@umd.edu