Assessing the Impact of Land Cover Spatial Resolution on Forest Fragmentation Modeling James D. Hurd and Daniel L. Civco Center for Land use Education And Research (CLEAR) Department of Natural Resources Management & Engineering The University of Connecticut U-4087, Room 308, 1376 Storrs Road Storrs, CT James D. Hurd and Daniel L. Civco Center for Land use Education And Research (CLEAR) Department of Natural Resources Management & Engineering The University of Connecticut U-4087, Room 308, 1376 Storrs Road Storrs, CT

Outline The Forest Fragmentation Model Application to land cover of different spatial resolutions Concluding remarks The Forest Fragmentation Model Application to land cover of different spatial resolutions Concluding remarks

Forest Fragmentation Modeling

Developed by Riitters et al. (2000) to assess global forest fragmentation from 1 km land cover data. Adapted for use on Landsat derived land cover information (30-meter spatial resolution). Categorizes forest pixels into 6 types: Core forest Perforated forest Edge forest Transition forest Patch forest Undetermined forest Background Forest Fragmentation Model

9x9 Analysis Window Forest Pixel Non-Forest Pixel Based on Image Convolution. Uses a roving analysis window of fixed size to determine vales of Pf (amount) and Pff (adjacency). Forest Fragmentation Model How It Works

Pf = 57 forest pixels 81 total pixels = x9 Analysis Window Forest Pixel Non-Forest Pixel Pf = proportion of forest pixels in analysis window. Forest Fragmentation Model How It Works

Forest Pixel Non-Forest Pixel Pf = 57 forest pixels 81 total pixels = 0.70Pff = 86 pixel pairs, both forest 119 pixel pairs, at least one forest = pixel pairs in a 9x9 window (72 vertical, 72 horizontal) 9x9 Analysis Window Pff = how connected are those forest pixels. Forest Fragmentation Model How It Works

Core forest, Pf = 1.0 Perforated forest, Pf > 0.6 and Pf – Pff > 0 Edge forest, Pf > 0.6 and Pf – Pff < 0 Transition forest, Pf 0.4 Patch forest, Pf < 0.4 Undetermined forest, Pf > 0.6 and Pf = Pff Forest Fragmentation Model How It Works (Riitters et al., 2000)

Core Forest - all surrounding grid cells are forest. Perforated Forest - the interior edge of a forest tract such as would occur around a small clearing or house lot. Edge Forest - the exterior edge of a forest tract such as would occur along a large agricultural field or urban area. Transitional Forest - about half of the surrounding grid cells are forest. Patch Forest - less than 40% of surrounding grid cells are forest. Definitions Forest Fragmentation Model

Pf = 0.70 Forest Pixel Non-Forest Pixel Forest Fragmentation Model How It Works

Pf = 0.70 Pf - Pff = = How It Works Forest Pixel Non-Forest Pixel EDGE FOREST Forest Fragmentation Model

9x9 analysis window27x27 analysis window 81x81 analysis window Analysis windows of different sizes can be applied. As analysis window size increases, the amount of core forest decreases. Analysis Window Sizes 9x9 27x27 81x81 Forest Fragmentation Model

Three Related Items to Consider 1. Spatial resolution of input land cover. 2. Width of desired edge (i.e. how far from a non- forested feature do you need to be before you are in core forest?). 3. What analysis window size will you use? Forest Fragmentation Model

Core Forest to Non-forest n x n pixel analysis window, where n is odd minimum pixel distance = 1 + [(n – 1) / 2] Minimum distance = minimum pixel distance * pixel resolution A core forest pixel will be at least the minimum distance from a non-forest pixel (pixel center to pixel center).

Core Forest to Non-forest 9x9 analysis window = 1 + [(9 - 1) / 2] = 5 pixels For 30 m pixels = 5 x 30 = 150 m (pixel centers) (5 x 30) – 30 = 120m (pixel edges) 5 pixels (150 m) (120 m)

Three Related Items to Consider 1. Spatial resolution of input land cover. 2. Width of desired edge (i.e. how far from a non- forested feature do you need to be before you are in core forest?). 3. What analysis window size will you use? Forest Fragmentation Model

Application to Land Cover of Different Spatial Resolutions Using Analysis Windows of Same Pixel Dimensions

1 - meter5 - meter10 - meter 30 - meter Larger spatial resolution created by degrading the 1-meter spatial resolution land cover Land Cover

Forest Fragmentation Result 1 - meter5 - meter10 - meter 30 - meter 5 x 5 Analysis Window

Forest Fragmentation Result 1 - meter5 - meter10 - meter 30 - meter 15 x 15 Analysis Window

Forest Fragmentation Result 1 - meter5 - meter10 - meter 30 - meter 27 x 27 Analysis Window

Forest Fragmentation Result 1 - meter5 - meter10 - meter 30 - meter 81 x 81 Analysis Window

Application to Land Cover of Different Spatial Resolutions Using Analysis Windows of Same Areal Extent

Land Cover Larger spatial resolution created by degrading the 1-meter spatial resolution land cover 1 - meter5 - meter10 - meter 30 - meter

271x27155x5527x27 9x9 Analysis Window Area = approx. 7.3 hectares Forest Fragmentation Result 1 - meter5 - meter10 - meter 30 - meter

30 – meter, 9x9 1 – meter, 271x2715 – meter, 55x55 10 – meter, 27x27

Pf = Pff = Pf - Pff = x9 Analysis Window 30 – meter Land Cover 9x9 Analysis Window PERFORATED FOREST

Pf = Pff = Pf - Pff = x27 Analysis Window 10 – meter Land Cover 27x27 Analysis Window EDGE FOREST

Pf = Pff = Pf - Pff = x55 Analysis Window 5 – meter Land Cover 55x55 Analysis Window EDGE FOREST

Pf = Pff = Pf - Pff = x271 Analysis Window 1 – meter Land Cover 271x271 Analysis Window EDGE FOREST

Core forest, Pf = 1.0 Perforated forest, Pf > 0.6 and Pf – Pff > 0 Edge forest, Pf > 0.6 and Pf – Pff < 0 Transition forest, Pf 0.4 Patch forest, Pf < 0.4 Undetermined forest, Pf > 0.6 and Pf = Pff Edge/Perforated Definition

Land Cover 9x9 Analysis Window 9x9 Analysis Window applied to 30-meter spatial resolution land cover Altering Definition of Edge/Perforated

Results of Forest Frag. Model using a 27x27 Analysis Window on 10m Land Cover Riitters Original Definitions Perforated Pf – Pff > 0 Edge Pf – Pff < 0 Altered Definitions Perforated Pf – Pff > Edge Pf – Pff < Altered Definitions Perforated Pf – Pff > -0.1 Edge Pf – Pff < -0.1 NOT SO GOODBETTER MORE LIKE 30m 9x9 FF RESULTS Altering Definition of Edge/Perforated

Riitters Original Definitions Perforated Pf – Pff > 0 Edge Pf – Pff < 0 Altered Definitions Perforated Pf – Pff > Edge Pf – Pff < Altered Definitions Perforated Pf – Pff > Edge Pf – Pff < NOT SO GOODBETTER MORE LIKE 30m 9x9 FF RESULTS Results of Forest Frag. Model using a 55x55 Analysis Window on 5m Land Cover Altering Definition of Edge/Perforated

Riitters Original Definitions Perforated Pf – Pff > 0 Edge Pf – Pff < 0 Altered Definitions Perforated Pf – Pff > -0.1 Edge Pf – Pff < -0.1 Altered Definitions Perforated Pf – Pff > Edge Pf – Pff < NOT SO GOODBETTER MORE LIKE 30m 9x9 FF RESULTS Results of Forest Frag. Model using a 271x271 Analysis Window on 1m Land Cover Altering Definition of Edge/Perforated

30- meter 9x9 (original definitions)10- meter 31x31 (Pf-Pff > OR < -0.1)30 – meter, Pf – Pff threshold = – meter, Pf – Pff threshold = – meter, Pf – Pff threshold = – meter, Pf – Pff threshold = -0.16

Class Edge Bias = * ln(r) Class Edge Bias Curve where r = land cover spatial resolution

CLEAR Website clear.uconn.edu

CLEAR Website

Downloadable Tool for ESRI ArcGIS 9.2

Concluding Remarks

When applying Forest Fragmentation model, three items to consider: - land cover spatial resolution - desired width of edge/perforation - analysis window size The spatial resolution (and landscape pattern) of the land cover impacts the result of the model: - it may be desirable to alter the definition of edge and perforated. Ultimately the results are only an approximation, but: - provide a powerful visual impact - allow for the quantification of forest fragmentation.

Assessing the Impact of Land Cover Spatial Resolution on Forest Fragmentation Modeling Center for Land use Education And Research (CLEAR) Department of Natural Resources Management & Engineering The University of Connecticut U-4087, Room 308, 1376 Storrs Road Storrs, CT Center for Land use Education And Research (CLEAR) Department of Natural Resources Management & Engineering The University of Connecticut U-4087, Room 308, 1376 Storrs Road Storrs, CT