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Development of a Remote Sensing-Based Method to Map Likelihood of Common Ragweed (Ambrosia artemisiifolia) Presence in Urban Areas

Figure 1

Figure 1
Ambrosia artemisiifolia illustration in Montreal. (a) Physical appearance of ragweed's leaves. (b) A colony of Common Ragweed in an non-built field. (c) Common Ragweed on roadsides. (d) Common Ragweed in a sport field. (Source: Direction de la Santé Publique Montréal).

Figure 2

Figure 2
(a) Common Ragweed field data sample of Montreal layered on a Worldview 2 image. (b) Field data sample of Valleyfield layered on a Rapid Eye image.

Figure 3

Figure 3
Segmentation and classification of Worldview 2 images of Montréal.

Figure 4

Figure 4
Visual-based sampling process of Common Ragweed using an object-oriented classification. (a) Ragweed's GPS samples transformed into radial buffers and layered on an object-based classified image. (b) Simultaneous visual control of samples on a false color and segmented images.

Figure 5

Figure 5
Monotonically increasing linear membership function.

Figure 6

Figure 6
Mean NDVI and spectral values of Common Ragweed in Near infrared Channels (760–895 nm) for various habitats; (a) in Montreal; (b) in Valleyfield.

Figure 7

Figure 7
Transformed divergence (a) and divergence (a), (b) for spectral samples from Rapid Eye and Worldview 2.

Figure 8

Figure 8
Overall median variances values of common ragweed through various habitats for selected predictive variables for Worldview 2 in Montreal and rapid eye in Valleyfield.

Figure 9

Figure 9
Mean reflectance values of A. artemisiifolia from Worldview 2 imagery of Montreal and from rapid eye imagery of Valleyfield.

Figure 10

Figure 10
Predictive maps of A. artemisiifolia: (a) from the green band of Worldview 2 imagery of Montréal; (b) from the green band of Rapid Eye imagery of Salaberry-de-Valleyfield; (c) From the green band of SPOT 4 imagery of Montreal.

Figure 11

Figure 11
Kappa index of agreement between observed and predicted common ragweed for various habitat: (a) in Montreal; (b) in Valleyfield.