Buffelgrass Growth within Urban Sub-Habitats Using High Resolution Aerial Photography

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1 Buffelgrass Growth within Urban Sub-Habitats Using High Resolution Aerial Photography Spencer Padgett The University of Arizona School of Geography and Development

2 Introduction What is buffelgrass? why is it an enemy of the Sonoran Desert? Why map buffelgrass? previous methods used Introduction to Tucson Airport Authority (TAA) study area Selection of sub-habitats Supervised classifications What are the land cover types Accuracy Assessment Georeferencing classified images Isolating the Buffelgrass land cover type Con statements Image differencing sequential year sets Digitizing buffelgrass colony boundaries Results Conclusion

Origin Africa, Southern Asia, semi-arid Europe Life

3 Common Names Buffelgrass, African foxtail grass, pasto buffel, zacate buffel Species Pennisetum ciliare Origin Africa, Southern Asia, semi-arid Europe Life Span Perennial (multiyear) Growth Form Graminoid (grass) Biology

Buffelgrass in the Sonoran Desert Introduced to Tucson as erosion control and livestock forage in 1940 s U.S. Soil Conservation Service Placed on the Arizona noxious weed list 2005, U.

4 Buffelgrass in the Sonoran Desert Introduced to Tucson as erosion control and livestock forage in 1940 s U.S. Soil Conservation Service Placed on the Arizona noxious weed list 2005, U.S Department of Agriculture Highly competitive against native vegetation for water and nutrients Low ignition threshold even during growing season Fine fuel Fills in the bare ground space between native vegetation creating a fire linkage Conversion of a succulentrich desert scrub into a buffelgrass dominated savannah

Invasive Species that requires monitoring Observation Treatment Follow up Fire Hazard/Fire Linkage Ruining Sonoran Desert native vegetation Current field mapping techniques have drawbacks and need

5 Invasive Species that requires monitoring Observation Treatment Follow up Fire Hazard/Fire Linkage Ruining Sonoran Desert native vegetation Current field mapping techniques have drawbacks and need improvement By foot Time Harsh environmental conditions By air Expensive Contracted This project would assess the feasibility of using free, high spatial resolution, orthophotography of a scene to detect and map buffelgrass Need orthophotos with <5 foot spatial resolution to successfully identify buffelgrass from other desert vegetation Why map buffelgrass?

6 8,080 acre parcel located between the I- 10 and I-19 freeways Free high resolution orthophotography available Area included in Southern Arizona Buffelgrass Coordination Center (SABCC) research grant Property contains vast areas of undisturbed desert and urban/aviation infrastructure

Data Year Flight Date(s) Resolution Bands 2002 August/September 1 foot 3-band (RGB) 2005 May 1 foot 3-band (RGB) 2008 April 1 foot 3-band (RGB) 2011 April 6 inch 4-band (RGB and NIR) Pima

7 Data Year Flight Date(s) Resolution Bands 2002 August/September 1 foot 3-band (RGB) 2005 May 1 foot 3-band (RGB) 2008 April 1 foot 3-band (RGB) 2011 April 6 inch 4-band (RGB and NIR) Pima Association of Governments Aerial Orthophotos NAD 1983 Arizona State Plane Central Zone SABCC surveyed buffelgrass vector data (polygon) NAD 1983 UTM Zone 12N Collected December, 2012 February, 2013

Sub- Habitat 1 Supervised classification Accuracy assessments Binary reclassification Image difference Buffelgrass colony digitizing Sub- Habitat 2 Supervised classification Accuracy assessments

11 Sub- Habitat 1 Supervised classification Accuracy assessments Binary reclassification Image difference Buffelgrass colony digitizing Sub- Habitat 2 Supervised classification Accuracy assessments Binary reclassification Image difference Methodology Tucson Airport Authority Sub- Habitat 3 Supervised Classification Accuracy assessments Binary reclassification Image difference Buffelgrass colony digitizing Sub- Habitat 4 Supervised classification Accuracy assessments Binary reclassification Image difference

Interest (AOI) with polygon selection tool to declare a land cover type After all user-specified land

12 Classifications Supervised Classifications are used to group pixels into distinct land cover groups Requires prior knowledge of scene to correctly identify and label land cover classes User selects Areas of Interest (AOI) with polygon selection tool to declare a land cover type After all user-specified land cover types are identified, a computer algorithm reassigns every pixel in the scene to a particular land cover type.

14 Isolating Buffelgrass Con( Statement, True Value, False Value) So for the buffelgrass binary reclassification, the following expression was used: Con(Classification_Raster = = 14, 1, 0)

21 190% Increase

28 155% Increase

30 Percent Change Results All Group Total Growth 25% 20% 15% Group 1 Group 2 Group 3 10% Group 4 5% 0% Year date sets

31 Percent Change Results All Group Total Loss 25% 20% 15% 10% Group 1 Group 2 Group 3 Group 4 5% 0% Year date sets

32 Conclusion There was a strong connection between buffelgrass growth and colony location when looking alongside roadways, tarmac, and urbanized boundaries There was an average growth rate of 19% per year in the digitized subsections of study groups 1 and 3 Locating and monitoring buffelgrass colony locations was much more difficult in a desert scrub scene Successfully integrated tools and techniques commonly found in remote sensing and GIS to produce an analysis for buffelgrass identification and growth habits within an urban setting.

33 References "ArcGIS Help 10.1: Georeferencing Tools." ArcGIS Help 10.1: Resource Center. ESRI, n.d. Web. 05 Dec < Agius, B Forging changes in an American landscape: invasive plant species at the Saugus Iron Works National Historic Site. Technical Report NPS/NER/NRTR 2005/10. National Park Service.Woodstock, VT. Biging, G. and Congalton, R Advances in forest inventory using advanced digital imagery, in Proceedings of Global Natural Research Monitoring and Assessments': Preparing for the 21st Century. Venice, Italy, September, Vol. 3, "Biology." SABCC (Southern Arizona Buffelgrass Coordination Center). SABCC, n.d. Web. 05 Dec < Olsson, A.D., Betancourt, J., McClaran, M.P., Marsh, S.E., Sonoran Desert Ecosytstem transformation by a C4 grass without the grass/fire cycle. Diversity and Distributions 18(1):10-21 The Nature Conservancy Cenchrus ciliaris L. (syn. Pennisetum ciliare) (Buffelgrass, anjangrass, African foxtail grass). The Nature Conservancy, Wildlands Invasive Species Team, Weed Alert. WRCC, Arizona Climate Summaries. Western Regional Climate Center. Accessed: April 19, 2010 Ziegler, A.D., Warren, S.D., Perry, J.L. and T.W. Giambelluca Reassessment of revegetation strategies for Kaho olawe Island, Hawai i. Journal of Range Management 53: Rutman, Sue. "Buffelgrass: Enemy of the Sonoran Desert." Invasive Plant Species - Organ Pipe Cactus National Monument. United States National Park Service, June Web. 5 Dec < Image credit: SABCC

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