1 2 3 4 5 6 7 8 9 10 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 992 996 1017 1000 1000 995 999 998 930 1023 1013 1002 1000 1031 1003 1000 1007 1009 1016 1012 1011 1013 1015 999 1018 1017 1004 1016 1010 1008 1011 1024 1013 1008 1000 998 1018 1008 997 996 1017 1014 1020 1016 1013 1017 69.7 69.7 72.3 37.4 11.0 59.0 62.0 3.6 19.0 71.9 11.1 8.4 15.9 33.8 34.7 16.1 9.0 42.8 20.7 41.0 8.2 17.5 13.6 14.9 9.6 8.3 49.5 10.1 1.7 4.4 24.1 1.6 8.3 18.2 27.5 56.9 6.2 2.4 4.4 53.8 9.8 21.4 59.9 23.0 70.1 44.9 SE 1.3 1.1 1.2 1.3 1.0 1.4 1.4 0.6 1.3 1.3 1.0 0.9 1.1 1.5 1.5 1.1 0.9 1.3 1.2 1.4 0.9 1.2 1.1 1.1 0.9 0.8 1.4 0.9 0.4 0.6 1.1 0.4 0.8 1.2 1.3 1.2 0.6 0.4 0.6 1.2 0.6 1.0 1.0 0.8 1.2 1.1 58.1 53.0 43.9 11.5 5.5 35.6 40.7 1.3 12.6 47.8 5.9 0.7 1.0 23.4 27.5 6.8 2.2 31.0 3.9 34.3 1.8 11.2 11.4 6.2 0.8 3.3 38.0 6.3 1.1 1.9 13.4 0.3 1.2 13.2 10.8 43.4 3.3 0.7 2.5 50.1 7.8 12.8 50.0 17.8 55.9 30.5 11.6** 16.7** 28.4** 25.9** 5.5** 23.4** 21.3** 2.3** 6.4** 24.1** 5.2** 7.7** 14.9** 10.4** 7.2** 9.3** 6.8** 11.8** 16.8** 6.7** 6.4** 6.3** 2.2* 8.7** 8.8** 5.0** 11.5** 3.8** 0.6** 2.5** 10.7** 1.3** 7.1** 5.0** 16.7** 13.5** 2.9** 1.7** 1.9** 3.7** 2.0** 8.6** 9.9** 5.2** 14.2** 14.4** Environmental Management (2010) 46:378–390 Table 3 Difference between photo-interpreted and NLCD 2001 derived tree canopy cover values by mapping zone Zone n Overall percent tree canopy cover Table 3 continued Zone n Photo NLCD Difference Overall percent tree canopy cover NLCD Difference 14.5** 3.7** 11.4** 16.8** 6.0** 12.3** 14.7** 14.8** 17.6** 8.1** 19.0** 14.9** 14.6** 17.3** 11.4** 9.4** 6.5** 7.5** 15.1** 385 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 1015 1017 999 1000 1016 1019 1012 1000 997 1020 1000 1020 998 1014 1015 1013 986 1003 1009 Photo 59.5 15.8 47.5 58.6 15.3 79.1 70.4 65.9 40.4 75.0 58.9 67.4 52.1 72.3 61.4 62.6 75.0 70.1 84.7 SE 1.2 0.8 1.1 1.2 0.8 1.0 1.2 1.2 1.4 0.9 1.2 1.2 1.3 1.0 1.2 1.1 1.1 1.2 1.0 45.0 12.1 36.1 41.8 9.3 66.8 55.7 51.1 22.8 66.9 39.9 52.5 37.5 55.0 50.0 53.2 68.5 62.6 69.6 n Number of photo interpreted points, Photo photo-interpreted value, SE standard error of photo-interpretation estimate, NLCD NLCD derived cover value, Difference Photo value minus NLCD value * Signiﬁcant difference at 95% conﬁdence level; ** Signiﬁcant dif- ference at 99% conﬁdence level In comparing NLCD tree canopy cover data with vari- ous other estimates of tree canopy cover in Syracuse, NY, NLCD produced the lowest tree cover estimate (12.7%), which was much lower than the other canopy estimates that ranged between 21.4 and 26.6% tree cover (Walton and others 2008). Contrasting NLCD impervious and canopy estimates with cover estimates derived from higher resolution imagery within a sampled sub-watershed in urban and suburban Baltimore, MD, revealed that NLCD-derived tree canopy and impervious cover estimates were 10 and 7%, respectively, below the higher resolution estimates (Smith and others 2010). This difference was attributed to ﬁne- scale variations in canopy (small patches of trees) and impervious cover (smaller buildings and noncontiguous pavement) that were not detected by the NLCD method. Smoothing of ﬁne scale variation within a coarser resolu- tion datasets has been noted in many other studies (Wickham and others 2010; Maxwell and others 2008). The limitations of photo-interpretation methods can contribute to the differences found between NLCD and photo-interpreted estimates of tree canopy and impervious cover. One limitation is the date of photo-interpreted 123