Some Thoughts on Shifts in Biome SeasonalityGeoff Henebry, South Dakota State University

We need to unpack this “new” phrase

1) “Shifts” implies an observable baseline against which to quantify a change and further implies that the shift is significant

2) “Biome” implies an emergent vegetation-climate association

3) “Seasonality” implies quasi-periodic abiotic phenomena

What about phenology? GIScCEGIScCE

Phenology has been defined as the study of the timing of recurring biological events, the causes of their timing, their relationship to biotic and abiotic forces, and the inter-relations among phases of the same or different species.

J.Y. Ewusie, 1992

Source: Ewusie, J.Y. 1992. Phenology in Tropical Ecology. Accra: Ghana Universities Press. 109 pp.

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Some Useful Distinctions

Phenology has traditional been linked to species

Land Surface Phenologies (LSPs) are the seasonal spatio-temporal patterns of the vegetated land surface [as observed by synoptic sensors at spatial resolutions and extents relevant to meteorological processes in the

atmospheric boundary layer] (de Beurs and Henebry, 2004 RSE;

2005 GCB; 2005 IJRS; 2008 JClim).

NASA Community White Paper on “Phenology” (Friedl et al.

2006) describes the concept of LSPs and stresses that LSPs are intrinsically mixtures of biotic & abiotic signals

Strong latitudinal & altitudinal controls on LSPs

Various shades of LSPs• Spring-green• Rain-green• Ever-green• Never-green

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What are some aquatic aspects of phenology/seasonality?

Various shades of aquatic: Inland vs. Coastal vs. Bluewater

Inland distinctions: wetlands, lakes, reservoirs, perennial vs. intermittent streams, rivers & their floodplains

Aquatic phenomena: Lake ice on/off, onset of meltwater flows, flood-pulse events, algal/cyanobacterial blooms, ...

What is common to terrestrial & aquatic phenologies and/or seasonalities?

Human modulation (LCLUC, ag mgmt, pollution, invasive & introduced species, etc.)

Atmospheric modulation (ENSO, NAM, PDO, etc.)

Solar modulation? GIScCEGIScCE

Kryjov, VN, and C-K Park. 2007. Solar modulation of the El Niño/Southern Oscillation impact on the Northern Hemisphere annular mode. GRL 34:L101701

What are key challenges?

Multiplicity of Methods + Multiplicity of Targets = Confusion

The nomenclature void must be addressed !

Land Surface Phenology Variable Intercomparison Project initiated by Mike White, USU, and Kirsten de Beurs, VT, at 2007 AGU phenology sessions.

What are appropriate spatial units for characterizing phenology/seasonality? Pixels? Ecoregions? Ad-hoc units? MAUP=modifiable areal unit problem

What are appropriate temporal units for characterizing phenology/seasonality? Calendar time? Compositing periods? Thermal time?

What are appropriate methods to characterize “shifts” and assess their significance? Step changes vs. Trends (accumulations of insignificant changes)

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AGDD

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Changes in LSP following the collapse of the Soviet Union are not uniform across Kazakhstan (de Beurs and Henebry 2004, 2005).

CENTRAL ASIATrends in

MODIS NBAR NDVI (C4 CMG)2001-2006 DOY 65-241

Revealed using theSeasonal Mann-Kendallnonparametrictrend test corrected for autocorrelation (de Beurs and Henebry 2004 GRSL)

Red: |SMK lt 0|Green: SMK gt 0Blue: mean NDVI

White: CountriesBlue: RiversYellow: Coastlines

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White: CountriesBlue: RiversBrown: Coastlines

CENTRAL ASIATrends in

MODIS NBAR NDVI (C4 CMG)2001-2006 DOY 65-241

Revealed using theSeasonal Mann-Kendallnonparametrictrend test corrected for autocorrelation (de Beurs and Henebry 2004 GRSL)

Red: |SMK lt 0|Green: p le 0.01Blue: mean NDVI

CIRCUM-POLAR Trends in

MODIS NBAR NDVI (C4 CMG)

2000-2006 DOY 97-257

Red: 1-(p le 0.01)Green: mean NDVI ge 0.1Blue: SMK trend test gt 0

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Significant opportunities for the research themeShifts in Biome Seasonality

Blending of datastreams from multiple sensors/platforms

• Active microwave • Passive microwave• Thermal and mid-IR (3-5 m)• Geostationary optical• Polar orbiting optical

to develop a comprehensive suite for characterizing land surface phenologies & seasonalities in different biomes/ecoregions.

Useful for monitoring, change analysis, impacts assessment, modeling (carbon, water, nutrients, weather, climate, land use, habitat,…), and ecological forecasting.

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