Remote Sensing Grassland Phenology in the Greater

Yellowstone Ecosystem: Biophysical Correlates, Land Use Effects and

Patch Dynamics

November 28th, 2012Nathan Piekielek

Phenology in Ecology• Population dynamics and migration

– Boone et al. 2006; Andreo et al. 2008

• Spatial patterns of plant, bird and other diversity– Phillips et al. 2008; Nightingale et al. 2008

• Fuel accumulation and drying– Westerling 2006; Littell et al. 2009

• Detection of forest insect outbreak and recovery– deBeurs and Townsend 2008; Spruce et al. 2011

• Nutrient cycling– Potter 2001; Risch and Frank 2010

• Biological response to climate change– Myneni et al. 1997; Cleland et al. 2007

• Integrated analyses with hydrologic cycle– Cayan 2001; Sun et al. 2008

Jan 17 Oct 16May 9 Jul 28

Photo credit: Bill Berg, CoolWorks.com

METRIC NAME INTERPRETATION

SOS Start of Season Start of the growing season; green-up

EOS End of Season End of the growing season; senescence

MAX Maximum NDVICombination of peak biomass and

greenness

INDVI Integrated NDVI Estimate of total annual productivity

Research Questions

1. What are the biophysical correlates and likely drivers of grassland LSP in the GYE?

a) How well do correlates predict LSP across the study-area?

2. How does land use modify grassland LSP from its natural biophysical state?

3. What are the seasonal patch-dynamics of green/growing grasslands in the study area?

Biophysical Correlates

• SRAD outer envelope control on timing

• Water or VPD in every model except SOS

• Temp. only in SOS

– Impact of warming mediated by seasonal water-balance

• Influence of snow-dynamics is spatially-variable

• EOS is not captured well by models

SNOWMELT

SO

S

Methods

1. Develop land use map

2. Apply biophysical models of natural LSP

3. Compare modeled natural LSP to observed actual LSP under different land uses

SOS

EOS

MAX

INDVI

Urb (n=9) Suburb (n=20) Exurb (n=39) Rur (n=51) Ag (n=155)

Ecological Implications

(Mckenzie 2001)

Banff, Alberta

• Landscape context for ungulate preference for private lands that has been observed by others (Thompson and Henderson 1998)

• Suggests future wildlife management challenges in GYE?

• Future modification and ecological impacts of land use are highly dependent on aesthetic preferences and values of future residents (Buyantuyev and Wu 2009)

Patch Dynamics

Late-season important time for ungulates to graze green forage

– weight gain, reproduction etc.

EARLY SEPT. CURRENT

Implications

5 degree C growing season temperature increase

EARLY SEPT. FUTURE

15 day earlier EOS on ave.

67% reduction in Sept. green forage area

ImplicationsClimate and land use change

in tandem:– Late-season green patches are

almost exclusively on private lands

– Migration a threatened ecological process in GYE?

– What are the management options?

GREEN FORAGE IN STUDY-AREA EARLY SEPT

Funding

1) NASA Applications Program2) Montana Institute on Ecosystems

Climate Datasets provided by:1) Forrest Melton and the NASA Ecological Forecasting Laboratory:

Landscape Biodiversity Laboratory

http://ecocast.arc.nasa.gov/