MODERATE RESOLUTION IMAGAINING SPECTROMETER (MODIS) SATELLITE DATASETS IN MONITORING

LANDSCAPE SCALE FIRE EVENTS ON THE REFUGIO-GOLIAD PRAIRIE CONSERVATION AREA, TEXAS

Acknowledgments We thank the Fire Learning Network for challenging us and funding our more innovative projects on this landscape. We would also like to thank Steven Gilbert,

GIS Manager TNC, Texas for transforming the MODIS datasets into usable formats and providing technical support. Rich Kostecke Assoc. Director of

Conservation - Research & Planning provided advice on data analysis, and provided a technical review of results from this project.

Introduction The Refugio-Goliad Prairie (RGP) Fire Learning Network (FLN)

Demonstration Landscape (664,000 acres) is located on the Texas

Gulf Coast within the Gulf Coast Prairies and Marshes Ecoregion

(Map 1). To maintain and restore prairie we must reinvigorate the

vanishing culture of fire in private landowners to meet conservation

and socio-economic goals. This study is an attempt to quantify and

set a baseline for monitoring landowner burning, and other fire

events since 2001.

Materials and methods Two MODIS datasets were acquired; one depicting burned areas and the other

depicting point fire detections (hot spots), and the two datasets were compared

against each other. The MODIS Burned Area (BA) product (Roy et al. 2002, 2005,

2008) detects the approximate date of burning at 500 m by locating the

occurrence of rapid changes in daily surface reflectance time series data. The

algorithm maps the spatial extent of recent fires and not of fires that occurred in

previous seasons or years. The dataset was obtained from: http://modis-

fire.umd.edu/Publications.html#3. The Fire Detection (FD) product identifies fires

and other thermal anomalies detected at a spatial resolution of 1km. Each 1km fire

detection represents the geographic location of a detected fire, but not the actual

fire size and often more than one detection for a single fire. The actual size of a

detected fire can be much smaller than the 1km spatial resolution of the data. FD

datasets for 2001 – 2003 were obtained from USDA Forest Service Remote

Sensing Applications Center (RSAC): http://activefiremaps.fs.fed.us/gisdata.php.

Analysis of these datasets was investigated to see if they could validate the

questionable S2 aerial survey, and if MODIS could provide a surrogate for fixed-

wing aerial surveys.

Results: Season 1 December 2007 – March 2008 We are confident the S1 aerial survey and prescribed burns conducted by

TNC comprise all fire events on RGP providing a solid foundation for

determining the likelihood of MODIS datasets identifying these

occurrences. In the aerial survey, 23 fire events covering 19,858 acres

were identified, of that 26% (N = 6) were detected by BA, and 57% by FD

(N = 13 fires, 45 individual detections). The two datasets combined

detected 69.5% of the fires (Fig. 3, Map 2).

Figure 3: Percentage Landowner prescribed Burns and Wildfires

(Fire Events) Detected in S1 (March 2008 Aerial Survey)

Conclusions To monitor and measure conservation progress on this landscape it is imperative that we have data

on the frequency and spatial extent of all fire events on the landscape. It is realized that these are

small sample sizes, and although initially promising the BA dataset only detected an average of 27 %

of the three sets of known burn events in the two seasons. The BA product failed to detect 5 fires

more than 1,000 acres in size so in this analysis it is incapable of providing the needed information.

The FD dataset appears to be more useful by detecting an average. Although FD detected 46.5% of

the same three sets known fire events it can only inform us of trends. When we combined all the FD

datasets from 2001 – 2011 (Fig. 7, Map 4), the years conducive for burning are clearly identifiable

along with the dramatic increase in the number of non-TNC implemented fire events. We can attribute

this trend to landowners once again embracing fire management. Continuing to track these trends

using the FD datasets can be a valuable metric for guiding conservation efforts.

References Pereira, J. M. C., Chuvieco, E., Beaudoin, A., & Desbois, N. (1997). Remote sensing of burned areas: a review. A review of remote sensing methods for the study

of large wildland fires. In E. Chuvieco (Ed.), (1997). Report of the Megafires Project ENV-CT96-0256, August 1997, ( pp. 127–183). Alcala de Henares,

Spain: Universidad de Alcala.

D.P. Roy, L. Boschetti, C.O. Justice, J. Ju, The Collection 5 MODIS Burned Area Product - Global Evaluation by Comparison with the MODIS Active Fire Product,

2008. Remote Sensing of Environment, 112, 3690-3707. (PDF File, 4.5 MB)

Roy, D.P., Jin, Y., Lewis, P.E., Justice, C.O. 2005. Prototyping a global algorithm for systematic fire-affected area mapping using MODIS time series data. Remote

Sensing of Environment, 97:137-162. (PDF File, 4 MB)

Roy D.P., Lewis P.E., Justice C.O. 2002. Burned area mapping using multi-temporal moderate spatial resolution data – a bi-directional feflectance model-based

expectation approach. Remote Sensing of Environment, 83:263-286. (PDF File, 2.3 MB)

Roy, D. P., Giglio, L., Kendall, J. D., & Justice, C. O. (1999). Multitemporal active-fire based burn scar detection algorithm. International Journal of Remote Sensing,

20, 1031– 1038.

Fig. 1. A MODIS satellite

(Aqua or Terra) imaging the globe

Fig. 2. Fires detected by a MODIS satellite

over a 6-day period (January 17 – 23, 2012)

Season 2 (December 2010 – March 2011) Aerial surveys conducted in April 2011 for S2 yielded questionable results

since green-up allowed little contrast in burned vs. unburned areas and they

were difficult to distinguish. The technicians believed they identified 32 fire

events covering 16,907 acres. BA confirmed 18.7% (N = 6) of those events

and FD confirmed 37.5% (N = 12 fires, 67 individual detections). The two

datasets combined confirmed 43.8% ((N = 14) (Fig. 5, Map 3)).

Figure 5: Percentage Landowner prescribed Burns and Wildfires

(Fire Events) Detected in S2 (April 2011 Aerial Survey)

Map 1. The RGP Landscape is the largest

remnant of coastal prairie that once extended

from Louisiana to Tamaulipas, Mexico

spanning 24,000,000 acres. It is the last place

the Attwater’s prairie chicken survived and is

now being repatriated on private ranches

through safe harbor agreements administered

through the USFWS.

Figure 4: Percentage of TNC Burns Detected in S1 (December 2007 –

March 2008)

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Burned Area Detections Hot Spot Detections Combined

During S1, TNC conducted 17 prescribed fires on the landscape covering 8,762

acres. MODIS BA detected 47% of fires (N = 8), and FD detected 35% (N = 6,

21 individual detections). The two datasets combined detected 64.7% of these

fires (Figure 4, Map 2).

Figure 6: Percentage of TNC Burns Detected in S1 (December 2007 –

March 2008)

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Burned Area Product Hot Spot Detection Combined

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Burned Area Product Hot Spot Detection Combined

During S2 TNC conducted 21 prescribed fires on the landscape covering

8,579. BA detected 9.5% of these fires (N = 2) and FD detected 47.6%

(N = 10, 26 individual detections). The two datasets combined detected

52.3% of these burns (Figure 4, Table 4, Map 3).

All Fire Detections 2001 – 2011 FD datasets are readily obtainable back to 2001; all fire event records were

collected and analyzed through 2011 ((N = 808 (some fires log multiple

detections)). Few fire events occurred on the landscape prior to 2003, but we

see a dramatic increase after TNC established a presence on the landscape

and began demonstrating, and supporting education and outreach (Fig. 7).

Map 4 demonstrates that these events are well distributed throughout the

landscape. However, it is worrisome that much of the remnant prairie areas

do not appear to have been experiencing the frequent fire return intervals

needed to maintain them.

Figure 7: All MODIS Hot Spot Fire Detections 2003-3011 (does not

include Burned Area product datasets)

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TNC Prescribed Burns

Fire Events (landowner Rx and wildfire

Total Detections

Ray Guse and Kirk Feuerbacher – The Nature Conservancy, Victoria, TX

Wade Harrell, PhD - US Fish and Wildlife Service, Austin, TX

For further information contact Ray Guse: phone 361-220-1200; email: rguse@tnc.org Background Photo © Jeff Adams, USFWS

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Burned Area Product Hot Spot Detections Combined

Results: Season 2 Results: Fire Detections