Supplementary information
A note on measurement scale
All aspects of forest spatial pattern are scale-contingent and there is no single scale that is best for all applications. The first scale parameter in our analysis was window size. We used a 0.9801 km 2 window
(33 pixels X 33 pixels) and refer to that as a 1 km 2 neighborhood. For land cover maps similar to those derived from the global forest change database, smaller neighborhoods tend to identify more forest interior area because it is usually easier to achieve a specified threshold FAD in a smaller neighborhood than in a larger neighborhood (Riitters et al., 2002). For the smallest possible neighborhood size (1 pixel
X 1 pixel), FAD = 1 for all forest, and thus all forest area is by definition forest interior area. To the extent that larger neighborhood sizes identify less forest interior area, the scales of forest fragmentation can be determined by analyzing FAD in progressively larger neighborhood sizes. Results obtained for other reasonable choices of neighborhood size would not change our essential conclusion that elasticity of forest interior area with respect to total forest area was larger than one, even though the absolute values of the forest interior area estimates would naturally be different. The second scale parameter in our analysis was the threshold FAD value chosen to define forest interior. Lower thresholds identify more forest interior area because it is easier to achieve a lower threshold than a higher threshold. For the smallest possible (and trivial) threshold (FAD > 0), all forest area is forest interior area.
A note on the definition of forest
This study adopted the same definition of forest in 2000 as was used by Hansen et al. (2013). Forest was defined as a pixel with non-zero tree cover percentage, where a tree is vegetation taller than 5 m
(Hansen et al., 2013). The effect of that definition on comparisons with area estimates in earlier global assessments (e.g., FAO 2010) has been discussed (Mather 2005; Hansen et al. 2013; Coulston et al.,
2014). That definition was the only parsimonious method to derive a comparable forest map for the year 2012 employing the maps of forest gain and forest loss from the global forest change database, which are said to describe transitions to and from a state of non-zero tree cover (Hansen et al. 2013).
Our definition of forest can include areas not used (or managed) as forest, for example tree cover in agricultural and urban landscapes. We believe that such landscapes contain a small share of the total forest area and an even smaller share of the forest interior area because most forest and almost all forest interior occurs in forest-dominated landscapes (Riitters et al. 2000, 2002). We focused on the change in forest interior area relative to change in total forest area, and it is not likely that the large changes in forest interior area that we observed were due to forest change in agricultural or urban landscapes.
Supplemental table
Table 3 in the main text summarized global statistics within each terrestrial biome. A given biome may appear on different continents, thereby preventing comparisons across continents. For that reason,
Table S.1 was prepared to provide the same summary of global statistics by biome and realm (Olsen et al., 2001).

References
Coulston, J. W., Reams, G. A., Wear, D. N., & Brewer, C., K. (2014) An analysis of forest land use, forest land cover and change at policy-relevant scales. Forestry, 87, 267-276.
FAO (Food and Agriculture Organization of the United Nations) (2010) Global forest resource assessment
2010. Rome: FAO Forestry Paper 163.
Hansen, M. C., Potapov, P. V., Moore, R., Hancher, M., Turubanova, S. A., Tyukavina, A., Thau, D.
Stehman, S. V., Goetz, S. J., Loveland, T. R., Kommareddy, A., Egorov, A., Chini, L., Justice, C. O., &
Townshend, J. R. G. (2013) High-resolution global maps of 21st-century forest cover change. Science,
342, 850-853. (Data available on-line from: http://earthenginepartners.appspot.com/science-2013global-forest Date of access: 05/03/2014).
Mather, A. S. (2005) Assessing the world’s forests. Global Environmental Change, 15, 267-280.
Olson, D. M., Dinerstein, E., Wikramanayake, E. D., Burgess, N. D., Powell, G. V. N., Underwood, E. C.,
D’Amico, J. A., Itoua, I., Strand, H. E., Morrison, J. C., Loucks, C. J., Allnutt, T. F., Ricketts, T. H., Kura, Y.,
Lamoreux, J. F., Wettengel, W. W., Hedao, P., & Kassem, K. R. (2001) Terrestrial ecoregions of the world:
A new map of life on Earth. BioScience, 51, 933-938.
Riitters, K., Wickham, J., O’Neill, R., Jones, B., & Smith, E. (2000) Global-scale patterns of forest fragmentation. Ecology and Society, 4(2), 3 [online] URL: http://www.ecologyandsociety.org/vol4/iss2/art3/.
Riitters, K. H., Wickham, J. D., O’Neill, R. V., Jones, K. B., Smith, E. R., Coulston, J. W., Wade, T. G., &
Smith, J. H. (2002) Fragmentation of continental United States forests. Ecosystems, 5, 815–822.

Table S.1. Forest area and net change, forest interior area and net change, and components of net change of forest interior area from 2000 to 2012 summarized by terrestrial biome and realm (Olsen et al., 2001). These statistics are comparable to those shown in Table 3 in the main text.
Biome
Tropical &
Subtropical
Moist
Broadleaf
Forests
Tropical &
Subtropical
Dry Broadleaf
Forests
Tropical &
Subtropical
Coniferous
Forests
Temperate
Broadleaf
& Mixed
Forests
Temperate
Coniferous
Forests
Boreal
Forests &
Taiga
Tropical &
IndoMalay
Nearctic
Neotropics
Biome subtotal
IndoMalay
Nearctic
Neotropics
Biome subtotal
Australasia
IndoMalay
Nearctic
Neotropics
Palearctic
Biome subtotal
IndoMalay
Nearctic
Palearctic
Biome subtotal
Nearctic
Palearctic
Biome subtotal
Afrotropics
Realm
Afrotropics
Australasia
IndoMalay
Neotropics
Palearctic
Biome subtotal
Afrotropics
Australasia
1692.6
55.7
150.4
223.9
430.1
353.6
103.1
1902.7
208.6
3326.7
15956.6
167.0
54.7
311.3
8.8
1150.8
2000
10 3 km 2
3330.4
1072.7
3476.0
7797.2
280.3
5894.8
31.6
1632.2
879.9
2543.7
3692.8
7319.4
11012.2
9021.3
All forest area Forest interior area
-126.5
-0.1
-97.2
-23.2
-120.6
-174.8
-243.7
-418.6
-132.8
-113.7
-0.4
-0.6
-5.3
-6.3
-4.5
-0.8
-68.8
-2.2
-50.3
-582.1
-3.1
-0.9
-16.7
-0.1
-92.9
Change
10 3 km 2 %
-75.8
2000
10 3
km 2
-2.3 3222.2
-17.2
-185.6
-1.6
-5.3
991.9
2423.7
-300.0
-3.4
-3.8 6654.5
-1.2 82.8
-3.6
-1.9
-1.7
-5.4
-0.6
-8.1
13375.1
126.5
24.0
140.5
1.8
749.1
10 3 km 2
Change
-249.9
-52.9
-506.7
-620.7
-6.9
-1437.2
-10.6
-2.2
-25.3 -18.0
0.0
-134.6
%
-7.8
-5.3
-20.9
-9.3
-8.4
-10.7
-8.4
-9.3
-2.1
-18.0
Elasticity
--
3.4
3.3
3.9
2.4
7.0
2.9
4.5
5.6
3.4
3.6
2.2
-6.7
-0.7
-0.4
-2.4
-1.5
1041.9
18.5
52.3
116.7
187.5
-1.3
-0.7
235.9
65.3
-3.6 1117.1
-1.1 106.1
-1.5 1560.3
-172.7
-1.1
-1.4
-13.7
-2.3
-16.6
-6.0
-2.6
-15.8 -13.5
-18.3 -9.7
-5.8
-3.6
-203.2 -18.2
-5.7 -5.4
-168.9 -10.8
2.5
8.5
6.8
5.7
6.7
4.6
4.9
5.0
5.1
7.2
-2.1 3084.7
-0.4 13.2
-6.0 1013.2
-2.6 522.9
-4.7 1549.3
-4.7 2716.3
-3.3 4841.3
-3.8 7557.7
-1.5 8138.9
-393.8 -12.8
-0.2 -1.3
-208.7 -20.6
-55.4 -10.6
-264.2 -17.1
-291.4 -10.7
-493.2 -10.2
-784.6 -10.4
-407.8 -5.0
3.6
2.3
3.1
2.7
3.4
5.9
3.6
3.5
4.0
Components of interior area change
Net direct
10 3 km 2
Net indirect
10 3
km 2
Direct
%
-75.5 -174.4 69.8
-15.4 -37.5
-155.5 -351.2
70.8
69.3
-213.7 -407.0
-1.2 -5.7
65.6
81.9
-461.5 -975.7
-2.9
-0.4
-9.4
0.0
-60.6
-7.7
-1.8
-16.0
0.0
-74.0
32.1
72.9
80.9
63.0
90.9
45.0
-73.3
-0.2
-0.2
-3.0
-99.5
-0.9
-1.1
-12.8
-3.5 -14.8
-4.7
-0.5
-9.0
-1.9
-50.7 -152.5
-2.0 -3.7
-39.4 -129.5
42.4
82.3
83.0
80.7
19.0
66.0
79.3
75.0
64.9
76.7
-97.3 -296.6
0.0 -0.1
-72.6 -136.0
-17.0 -38.4
-89.6 -174.6
-160.3 -131.1
-197.0 -296.2
-357.3 -427.3
-129.6 -278.2
33.9
45.0
60.1
45.5
68.2
24.7
88.6
65.2
69.3

Subtropical
Grasslands,
Savannas &
Shrublands
Temperate
Grasslands,
Savannas &
Shrublands
Flooded
Grasslands &
Savannas
Montane
Grasslands &
Shrublands
Tundra
Mediterranean
Forests,
Woodlands &
Scrub
Deserts &
Xeric
Shrublands
Mangroves
Australasia
Nearctic
Neotropics
Palearctic
Biome subtotal
Afrotropics
Australasia
IndoMalay
Nearctic
Neotropics
Palearctic
Biome subtotal
Afrotropics
Australasia
IndoMalay
Neotropics
Palearctic
Biome subtotal
Nearctic
Palearctic
Biome subtotal
Afrotropics
Australasia
IndoMalay
Nearctic
Neotropics
Biome subtotal
Afrotropics
Australasia
Nearctic
Neotropics
Palearctic
Biome subtotal
Afrotropics
IndoMalay
Neotropics
Palearctic
Biome subtotal
Afrotropics
538.5
623.9
37.5
4.2
26.4
117.2
809.1
952.3
345.2
0.0
133.3
60.0
402.5
705.5
575.6
10.3
21.3
1267.6
10896.1
0.0
82.7
375.5
38.3
455.8
748.6
136.6
17.0
14.2
120.5
309.5
29.8
1108.0
42.5
239.5
47.5
20.7
398.5
627.6
65.8
-3.7
-0.2
-1.1
-3.0
-0.7 -16.3
-82.8 -18.8
-495.1 -5.6
0.0
-2.4
--
-9.7
-9.2 -11.9
-0.4 -10.1
-15.6 -12.6
-27.5 -12.0
-9.5
0.0
-4.7
-1.0
-3.0
--
-7.6
-4.2
-15.2 -3.8
-20.7 -4.6
-1.8 -6.7
-0.5 -13.8
-0.3 -3.2
-1.3 -4.1
-24.7 -4.7
-24.4 -14.0
-10.0 -5.7
-34.4 -9.8
-2.7 -12.4
-31.8 -24.4
-3.1 -19.8
-0.4 -9.4
-11.5 -12.9
-49.3 -19.0
-9.7 -16.0
0.0 -0.4
0.0
-1.2
-1.1
-7.0
-11.7 -12.6
-0.3 -10.4
-22.9 -13.0
-3.5 -5.9
-7.1
-6.7
-0.8
-0.1
-0.1
-1.2
-8.9
-20.8
-3.1
0.0
-3.6
-0.4
-17.4
-12.9
-2.0
-0.1
-0.6
-70.3
-205.8
0.0
-2.3
-8.5
-1.1
-8.9
-41.6
-3.0
-0.1
0.0
-2.9
-15.2
-0.9
-30.3 -2.7
-0.8 -1.8
-28.5 -11.9
-4.2 -8.8
0.2
-8.4
1.0
-2.1
-22.2
-1.1
-3.5
-1.7
-5.6
-2.2
-0.8
-0.3
-2.4
-4.9
-2.9
-1.3
-1.1
-2.1
-3.0
-0.5
-1.0
-1.1
-2.2
-0.9
-0.2
-2.7
-0.6
-4.3
-1.8
0.0
-2.8
-2.3
-2.8
-2.0
-0.3
-1.4
-2.8
-5.5
323.9
5.7
4.1
440.2
-1.9 8912.8
0.0
24.8
77.4
3.9
123.2
398.6
448.4
26.9
3.9
9.2
33.1
521.4
229.3
312.4
0.0
62.2
24.0
173.9
177.0
259.9
60.5
1.6
1.4
16.9
92.7
2.7
350.9
21.6
130.1
15.4
3.8
88.9
175.8
59.8
-4.4
-6.3
-0.6
-0.1
-0.1
-0.4
-7.6
-8.6
-3.0
--
-1.2
-0.2
-14.3
-4.4
-0.9
0.0
-0.1
-30.0
-2.8
-0.1
-0.5
-52.9
-160.6 -334.6
--
-1.0
-2.4
-0.1
-5.0
--
-1.4
-6.8
-0.3
-10.6
-10.8
-14.3
-1.2
-0.4
-0.2
-0.9
-17.1
-19.0
-6.5
--
-3.5
-0.8
-10.0
-5.6
-25.7
-2.7
0.0
0.0
-0.4
-2.1
-0.1
-18.8
-0.6
-21.2
-1.5
-0.1
-2.3
-5.3
-1.1
-23.6
-7.0
0.0
0.0
-0.8
-9.6
-0.1
-15.6
-2.1
-10.6
-1.5
-0.3
-9.1
-17.6
-2.4
2.9
4.3
3.3
4.6
6.4
3.9
4.3
5.5
3.4
--
2.8
6.9
3.2
3.1
3.3
2.2
5.8
3.4
2.9
--
3.4
5.2
3.7
6.4
3.4
7.2
0.5
3.6
2.9
2.6
3.6
3.6
6.7
2.1
2.3
-9.5
6.1
3.7
3.4
29.0
69.3
64.3
77.3
80.9
67.1
30.8
31.1
68.5
--
74.3
78.6
41.2
55.9
76.5
81.4
79.9
36.2
32.4
--
56.9
73.8
68.9
67.8
52.1
72.4
88.6
86.8
70.2
82.1
52.7
54.5
77.2
33.3
50.7
77.0
79.8
23.0
69.1

Australasia
IndoMalay
Neotropics
Biome subtotal
Global total
22.8
49.5
63.0
-0.1
-3.9
-1.3
201.1 -6.5
53411.2 -1711.0
-0.4
-7.9
-2.1
22.0
29.3
35.5
-0.3 -1.3
-8.8 -30.0
-3.6 -10.1
-3.2 146.6 -16.1 -11.0
-3.2 37791.4 -3756.2 -9.9
2.9
3.8
4.8
-0.1
-3.1
-0.8
-0.2
-5.7
-2.8
3.4 -5.0 -11.1
3.1 -1318.3 -2437.9
70.1
64.9
78.3
31.1
35.1