Examining Direct and Indirect Impacts of Environmental Change on Alpine Plant CommuniGes in California’s White Mountains Christopher Kopp & Elsa Cleland University of California, San Diego January 13, 2014 Outline •  Study system •  Vegeta1on resurvey •  Compe11on release experiment •  Conclusions Species ranges and climate change •  A species’ bioclima1c envelope helps define its distribu1on •  With rising temperatures, species are predicted to shi@ range margins upward and pole-­‐ward –  Contrac1ons at low eleva1ons and la1tudes •  Novel species interac1ons A+ or  A  B+ B+ C+ Past Future Species ranges and climate change predic1ons for the Great Basin •  For every 1 °C increase, ecological zones may rise 167 m •  3 °C increase  20-­‐50% species loss (Murphy & Weiss 1992) hmc.edu Study system: White Mountains maps.google.com hmc.edu White Mountains ElevaGon PrecipitaGon Temp 4344 m 456 mm/yr -­‐1.7 °C VegetaGon Zones Alpine Sub-­‐alpine Pinyon-­‐juniper woodland 142 mm/yr 13.3 °C 1200 m Desert scrub Outline •  Study system •  VegetaGon resurvey •  Compe11on release experiment •  Conclusions White Mountain Resurvey Mooney et al. 1962 Kopp & Cleland 2014 •  1961 •  2900 m – 4000 m •  Line transects every 150 m of eleva1on •  2010 •  2900 m – 4000 m •  Line transects every 150 m of eleva1on Three cushion species experienced significant declines in abundance 1961 2010 Kopp & Cleland JVS 25 (2014) 135-­‐146 Koeleria macrantha showed declines in abundance at upper eleva1ons calflora.org 1961 2010 Kopp & Cleland JVS 25 (2014) 135-­‐146 Sagebrush’s upper range limit advanced upwards 1961 2010 Kopp & Cleland JVS 25 (2014) 135-­‐146 Sagebrush advance •  3800 m in 1964 •  4102 m in 2012 –  Flowering at 3993 m Sagebrush advance Photo: Steven Travers Kopp & Cleland JVS 25 (2014) 135-­‐146 White Mountains climate shi@s 1961-­‐2010 (3800 m) •  Daily mean temperatures increased 0.98 °C •  Mean annual precipita1on declined 53 mm Kopp & Cleland JVS 25 (2014) 135-­‐146 R2=0.11 p=0.03 R2=0.23 p=0.001 R2=0.12 p=0.01 Strong Abio1c Influence •  Increasing temperatures and declining precipita1on  lengthening of growing season •  Increased temperatures posi1vely affect growth of sagebrush (Harte & Shaw 1995) –  Seed bank is refreshed yearly •  Nega1ve forces on cushion plant popula1ons –  Early snowmelt may subject alpine plants to more frequent early-­‐season frost mortality –  Drought stress Outline •  Study system •  Vegeta1on resurvey •  CompeGGon release experiment •  Conclusions Bio1c interac1ons with sagebrush •  Sagebrush is encroaching into the alpine •  How are alpine species responding to this novel species? Un-­‐encroached Alpine fell field Sagebrush encroachment How do plants respond to sagebrush encroachment? •  Grasses at 3700 m respond nega1vely to sagebrush presence 4.5 4.0 No sagebrush Sagebrush present * Cover (%) 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 Grass Forb How do species respond to release from sagebrush compe11on? •  Three eleva1ons –  2900 m, 3100 m & 3700 m •  Treatments –  No sagebrush present –  Sagebrush •  Le@ intact •  Removed •  2011 -­‐ 2013 Grass responds posi1vely to sagebrush removal in the alpine Change in Cover (%) Grass 1.0 0.8 0.6 0.4 0.2 0.0 -­‐0.2 -­‐0.4 -­‐0.6 -­‐0.8 -­‐1.0 B B B Ba Ba Ba Trifolium andersonii B Aa B 0.0 -­‐2.0 -­‐4.0 A A A -­‐6.0 *no Trifolium andersonii present at 2900 m -­‐8.0 -­‐10.0 -­‐12.0 2900 m 3100 m ElevaGon 3700 m B B B 3100 m 3700 m ElevaGon Control Removal Shrub Outline •  Study system •  Vegeta1on resurvey •  Compe11on release experiment •  Conclusions Abio1c and bio1c impacts may be transforma1ve to this alpine system •  Con1nued warming  –  con1nued declines of cushion plants –  con1nued advancement of sagebrush •  Sagebrush advancement nega1vely impacts grasses •  Taken together, alpine plant communi1es in the White Mountains could be significantly transformed Thank you! Field assistants Rosa Chung Kristen Richardson Melissa S1ne Kendra Ritchie Brianna Goehring (USFS) Funding Na1onal Science Founda1on White Mountain Research Center UC Natural Research System California Na1ve Plant Society Nevada Na1ve Plant Society The American Alpine Club Jean Marie Messier Fund UC San Diego Division of Biological Science ckopp@ucsd.edu
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