Lewis Smith Comps Fall 2015

transcript

Vegeta&on Change: A River Runs Through It

Riparian Successional Change as a Posi&ve Feedback

Loop to Climate Change

By Connor Lewis-‐Smith

Riparian Ecosystem 2

What is the Riparian Ecosystem? •  A biological feedback into

river geomorphology and hydrology

(Bendix and Hubb 2000). 3

•  Riparian vegeta&on succession is an ecological feedback to climate change

CO2 Concentra&ons

Flow Regime Change

Riparian Vegeta&on

Weather PaSerns

Floods

WeSer winters Increased flooding

Projected to con&nue to increase in severity. 5

Projected returns of present 100 year flooding

Hirabayahi et al. 2008

Historic Flooding In South Carolina

“Floodwaters break through a walkway in Columbia, S.C., Monday, Oct. 5, 2015. A]er a week of steady rain, the showers tapered off Monday and an inundated South Carolina turned to surveying a road system shredded by historic flooding” (AP Photo/Chuck Burton)

Far Reaching and Felt

•  On the Skagit River (WA), the magnitude of 50-‐year-‐return flood events is projected to increase 15% by the 2040s (compared to 1916-‐2006) (Tillmann and Siemann 2011).

Vegeta&on's Rela&onship to Floods

•  flood veloci&es may be substan&ally decreased as vegeta&on grows

•  or abruptly increased if the vegeta&on is destroyed (Bendix and Hubb 2000).

•  Shi] plant communi&es towards species with less ability to stabilize sediments

•  More intense, destruc&ve floods

Vegeta&on's Rela&onship to Floods

Basal Area of Three most abundant pioneer trees in semiarid riparian zone

Stromberg et al. 2010 collected data from San Pedro River basin in both wet and dry seasons Younger plants present in areas of higher intensity floods, dry sites have more exo&cs than na&ves. 11

Populus fremon-i Fremont coSonwood

(hSp://www.fireflyforest.com/flowers/2182/populus-‐fremon&i-‐fremont-‐coSonwood/)

Salix gooddingii Goodding Willow

(hSp://www.mswn.com/plants/database/plant/salix-‐gooddingii/)

Tamarix sp. Salt Cedar

(hSp://www.streamwebs.org/invasive-‐species-‐list/saltcedar-‐tamarix-‐ramosissima)

Na&ves to SW USA

Invasive to SW USA

Three Common Woody Species of the Riparian Environments in the SW USA

Shi]s in Vegeta&on Type

Stromberg et al. 2010 13

Droughts

Drier summers Decreased flow

Projected to con&nue to increase in severity.

Future Drought Projec&ons

Hirabayahi et al. 2008 15

•  Stream water sources threatened: – Snow pack dependent – Ground water/runoff dependent

Perry et al. 2013 •  Will posi&ve effects of climate change on riparian vegeta&on offset nega&ve effects?

•  Increased CO2 (+) •  Increased Water Stress (-‐)

Perry et al. 2013 Methods •  five of the most abundant western United States woody species:

•  Two na&ves (Populus deltoides spp. monilifera, Salix exigua)

•  Three exo&c (Elaeagnus angus-folia, Tamarix spp., Ulmus pumila).

•  Grown in a CO2-‐controlled glasshouse •  Different water-‐table decline rates to test the species response to drought under current and increased CO2 concentra&ons.

Results of CO2 and Water Decline

•  Elevated [CO2] increased mean total biomass by 15%

•  faster water-‐table decline rates on seedling biomass (70–97%)

•  Hindered na&ves more than exo&cs

Perry et al. 2013 19

Model of direct and indirect effects of climate change on flow regime

Tillmann and Siemann 2011

CO2 Concentra&ons

Flow Regime Change

Riparian Vegeta&on

Weather PaSerns

Riparian vegeta&on change is occurring, but how will it con&nue?

Modeling 22

Riparian Succession Model

Computer Based Modeling

•  Computer Aided Simula&on Model for In-‐stream Flow and Riparian vegeta&on model: CASiMiR-‐vegeta&on model

•  Modeling Succession Phase vs. Site Specific Features.

•  Inputs: grid-‐based topography, max. annual discharge shear stress, flood dura&on and mean/base water table eleva&on files. Rivaes et al.

2014 24

Rivaes et al. 2014

CASiMiR-‐Vegeta&on Model

Rivaes et al. 2014

Feedback to Climate Change Riparian vegeta&on will sequester

less carbon

No riparian vegeta&on to sequester carbon

Woody Riparian Vegeta&on Stores More CO2

Data from San Pedro River Basin March-‐December (primary growing season) totals of NNE were -‐63, -‐212, and -‐233 g C m-‐2 in the grassland, shrubland, and woodland, respec&vely

Net Ecosystem CO2 exchange based on Vegeta&on Type ScoS et al. 2006

Riparian Vegeta&on's Power as a Sink

•  Restoring and refores&ng such riparian zones to mature forest would increase carbon storage and improve water quality.

•  The carbon deficit along 57,700 km headwater Coastal Plain streams in North Carolina is equivalent to – 25TgC in 30-‐m-‐wide riparian buffer zones – 50TgC in 60-‐m-‐wide buffer zones.

Rheinhardt et al. 2012 31

Biomass of Riparian Vegeta&on in North Carolina

Rheinhardt et al. 2012

Mature Forest Regenera&ng Forest Perennial Herb Shrub/Sapling Annual Rowcrops

MgC/ha

Rivers as Sources of Atmospheric CO2

•  Emiqng 97 (+/-‐32) TgC per year

•  Posi&vely correlated with annual precipita&on

Butman et al. 2011 34

CO2 Concentra&ons

Flow Regime Change

Riparian Vegeta&on

More Floods and Droughts

Stress / destruc&on

Geophysical altera&ons

Butman, D. and P.A. Raymond. 2011. Significant efflux of carbon dioxide from streams and rivers in the United States. Nature Geoscience. 16 October 2011.

Hirabayashi, Y., Kanae, S., Emori, S., Oki, T. and M. Kimoto. 2008. Global projec&ons of changing risks of floods and droughts in a changing climate. Hydrological Sciences Journal 53(4) 754-‐772

Kernan, M. R., R. W. BaSarbee, and Brian Moss. 2010. Climate Change Impacts on Freshwater Ecosystems. Chichester, West Sussex, UK: Wiley-‐Blackwell, 2010.

Perry, L.G., Shafroth, P.B., Blumenthal, D.M., Morgan, J.A. and D.R. LeCain. 2013. Elevated CO2 does not offset greater water stress predicted under climate change for na&ve and exo&c riparian plants. Phytologist 197: 532-‐543

Rheinhardt, R.D., Brinson, M.M., Meyer, G.F. and K.H. Miller. 2012. Carbon storage of headwater riparian zones in an agricultural landscape. Carbon Balance Manag. 7:4

Stromberg, J.C., Lite, S.J. and M.D. Dixon. 2010. Effects of Stream Flow PaSerns on Riparian Vegeta&on of a Semiarid River: Implica&ons for a Changing Climate. River Research and Applica-ons. 26: 712-‐729

Tabacchi, E., Correll, D.L., Hauer, R., Pinay, G., Planly-‐Tabacchi, A.M. and R.C. Wissmar. 1998. Development, Maintenance and role of riparian vegeta&on in the river landscape. Freshwater Biology 40, 497-‐516

Tillmann, P. and D. Siemann. 2011. Climate Change Effects and Adapta&on Approaches in Freshwater Aqua&c and Riparian Ecosystems in the North Pacific Landscape Conserva&on Coopera&ve Region. Na-onal Wildlife Federa-on

Rivaes, R.P., Rodrıguez-‐Gonzalez1, P.M., Ferreira, M.T., Pinheiro, A.N., Poliq, E., Egger G., Garcıa-‐Arias A. and F. Frances. 2014. Modeling the Evolu&on of Riparian Woodlands Facing Climate Change in Three European Rivers with Contras&ng Flow Regimes. Ecohydrology Vol 9. No. 10

Bibliography

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Lewis Smith Comps Fall 2015

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