**3.1 Measured aboveground and foliage biomass over the Porcupine caribou habitat**

Table 1 summarizes the mean value, standard deviation, and range of aboveground biomass measured at sites within and around the Porcupine caribou winter and summer range along the Dempster Highway, Yukon, during the summer of 2004. Average values of measured aboveground biomass of sparsely treed woodland, low-high shrub lands, and mixed graminoids-dwarf shrub-herb lands were, respectively, 57.3, 11.1, and 2.3 t ha-1. Within each vegetation type, the ranges of measured aboveground biomass were very large. The standard deviations of measured aboveground biomass among sites were often larger than their corresponding mean values, especially for low-high shrubs and mixed graminoidsdwarf shrub-herb, and when all types of vegetation were considered. The measured aboveground biomass ranged from 10 to 100 t ha-1 for sparsely treed woodlands, from 1 to 100 t ha-1 for the low-high shrub sites, from 0.5 to 10 t ha-1 for mixed graminoids-dwarf shrub-herb sites. These measurements indicate that there are significant overlaps in the ranges of aboveground biomass between sparsely treed woodlands and low-high shrub sites, and between low-high shrub sites and mixed graminoids-dwarf shrub-herb sites.

Mapping Aboveground and Foliage Biomass Over the Porcupine Caribou

woodlands and all types mixed, but not for shrub and graminoids lands.

America JERS summer mosaic.

Sparse woodland

Low-high-Shrub

Graminoid s-dwarf shrub

All types

coefficients.

backscatter coefficient (JERS).

**Ln(**

*Ba* **) (t ha-1)**

> 0.5 1 1.5 2 2.5 **Landsat B4/B5**

Fig. 5. Scatter plots between ln(*Ba*) and Landsat B4/B5 as well as JERS-1/SAR backscatter

Habitat in Northern Yukon and Alaska Using Landsat and JERS-1/SAR Data 239

indices, and JESR-1/SAR backscatter coefficients. We used 3 × 3 pixels (i.e., 90 m by 90 m) averaged value in place of single pixel value in order to reduce the effect of erroneous spectral features, e.g., features of adjacent pixels may have been assigned to some field plots of the data due to errors in image registration and the location of sample plots. The Landsat images were re-sampled to 100 m resolution for matching the resolution of the North

For the sites along the Dempster Highway, we found that strong correlations exist between ln(*Ba*) and remote sensing signals (Table 3). When all types were mixed, the strongest correlation was found against the L-band JERS-1/SAR backscatter, followed by the Landat B4/B5 (Fig. 5). The Landsat bands 3 and 5 show strong negative relationships for the sparse

B3 B4 B5 B4/B5 SR NDVI SWVI JERS

*r* **-0.77 -0.18 -0.78 0.40 0.53 0.21 0.44 0.68**  *r*2 0.59 0.03 0.61 0.16 0.28 0.04 0.19 0.46

*r* **-0.17 0.04 -0.39 0.59 0.47 0.26 0.59 0.42**  *r*2 0.03 0.00 0.15 0.35 0.22 0.07 0.35 0.18

*r* **-0.13 0.22 0.01 0.21 0.26 0.31 0.18 0.64**  *r*2 0.02 0.05 0.00 0.04 0.07 0.10 0.03 0.41

*r* **-0.65 -0.02 -0.68 0.70 0.63 0.53 0.68 0.73**  *r*2 0.42 0.00 0.46 0.49 0.40 0.28 0.46 0.53

> -12 -10 -8 -6 **JERS-1 backscatter**

Table 3. Correlation coefficient (*r*) and coefficient of determination (*r*2) between ln(*Ba*) and remote sensing indices for mixed graminoids-dwarf shrub-herb, low-high shrub, sparse woodlands, and all types for aboveground biomass measurements along the Dempster Highway in 2004. Remote sensing indices include Landsat red band reflectance (B3), near infrared band reflectance (B4), shortwave infrared band reflectance (B5), ratio of B4/B5, simple ratio (SR = B4/B3), normalized differential vegetation index (NDVI = (B4 - B3)/(B4 + B3)), shortwave vegetation index (SWVI = (B4 - B5)/(B4 + B5)), and L-band JERS-1/SAR


Table 1. Mean value, standard deviation, and range of aboveground biomass measured at sites within and around the Porcupine caribou winter and summer range along the Dempster Highway, Yukon, during the summer of 2004.


Table 2. Mean value, standard deviation, and range of foliage biomass measured at sites within and around the Porcupine caribou winter and summer ranges along the Dempster Highway, Yukon during the summer of 2006, as well as at sites within and around the Porcupine caribou calving ground and summer range inside the Ivvavik National Park, Yukon during the summer of 2008. Also shown are statistics for the corresponding aboveground biomass measurements.

Similarly, the foliage biomass values measured at sites within a specific dominant vegetation type also varied significantly (Table 2). For example, foliage biomass ranges from 95.3 to 198.4 g m-2 for low-high shrub sites, 37.9–92.3 g m-2 for mixed graminoids-dwarf shrub-herb sites, 63.1–106.1 g m-2 for coastal plain tussock sites, and 0.0–20.0 g m-2 for hilltop rock lichen sites. Consequently, assigning aboveground or foliage biomass value to a site according to its vegetation type can result in substantial error (Gould et al., 2003; Walker et al., 2003).
