1 00:00:00,000 --> 00:00:00,680 2 00:00:00,700 --> 00:00:05,870 Forests are always changing. They're a very dynamic ecosystem. 3 00:00:05,890 --> 00:00:08,020 We've used data from the Landsat satellites 4 00:00:08,040 --> 00:00:10,110 to produce a comprehensive look at forest dynamics 5 00:00:10,130 --> 00:00:13,100 on the scale of human management and natural disturbances. 6 00:00:13,120 --> 00:00:16,890 Dark green pixels had no disturbances in the 25 years studied. 7 00:00:16,910 --> 00:00:20,380 Yellow shows where a disturbance happened in a particular year. 8 00:00:20,400 --> 00:00:24,450 At this scale, what really stands out are the large fires in the West 9 00:00:24,470 --> 00:00:29,320 and timber harvesting in the Pacific Northwest, Maine, and all across the Southeast. 10 00:00:29,340 --> 00:00:32,630 We need to know the rate of disturbance and how that rate is changing 11 00:00:32,650 --> 00:00:36,800 in order to understand how carbon is changing across the landscape. 12 00:00:36,820 --> 00:00:40,350 Here we can see the impact of policy decisions on forest dynamics 13 00:00:40,370 --> 00:00:42,980 The various protected areas around Broken Bow Lake 14 00:00:43,000 --> 00:00:44,140 remain largely undisturbed 15 00:00:44,160 --> 00:00:45,750 compared to the surrounding region, 16 00:00:45,770 --> 00:00:50,330 which flickers with the tell-tale patches of timber harvesting. 17 00:00:50,350 --> 00:00:53,310 Any disturbance, whether from fire or hurricanes, 18 00:00:53,330 --> 00:00:57,390 mining or logging, impacts how much carbon the forest can store. 19 00:00:57,410 --> 00:01:00,980 20 00:01:01,000 --> 00:01:02,940 The southern and central Appalachian Mountains, 21 00:01:02,960 --> 00:01:04,190 from Tennessee to West Virginia, 22 00:01:04,210 --> 00:01:05,910 are home to most of the disturbances 23 00:01:05,930 --> 00:01:09,030 resulting from mountaintop removal mining. 24 00:01:09,050 --> 00:01:12,780 Throughout Appalachia, coal mining has been a big industry since the 1860s, 25 00:01:12,800 --> 00:01:17,580 and mountaintop mining became dominant over the last 30 years. 26 00:01:17,600 --> 00:01:21,700 The Hobet Mine in Boone County, West Virginia, existed before 1986 27 00:01:21,720 --> 00:01:25,000 and has continued to expand throughout the course of this study. 28 00:01:25,020 --> 00:01:28,300 29 00:01:28,320 --> 00:01:30,160 The pattern we see at the Hobet Mine is 30 00:01:30,180 --> 00:01:34,970 replicated across the entire southern Appalachia. 31 00:01:34,990 --> 00:01:37,190 32 00:01:37,210 --> 00:01:39,460 We mostly think of hurricanes wreaking houses, 33 00:01:39,480 --> 00:01:41,930 flooding cities, and endangering lives. 34 00:01:41,950 --> 00:01:43,500 But they can also damage forests, 35 00:01:43,520 --> 00:01:46,080 knocking down wide swaths of trees. 36 00:01:46,100 --> 00:01:48,040 Hurricane Hugo was a category 4 storm 37 00:01:48,060 --> 00:01:51,400 when it struck South Carolina in September of 1989, 38 00:01:51,420 --> 00:01:55,130 and the scale of the disturbance shows in the 1990 data. 39 00:01:55,150 --> 00:01:56,780 Four and a half million acres of forest 40 00:01:56,800 --> 00:02:00,380 were affected by wind gusts and storm surges of salt water. 41 00:02:00,400 --> 00:02:01,680 Disturbances of this magnitude 42 00:02:01,700 --> 00:02:03,580 can release large amounts of carbon dioxide 43 00:02:03,600 --> 00:02:07,500 into the atmosphere as the trees decompose. 44 00:02:07,520 --> 00:02:11,390 Tornadoes leave long tracks of damaged forests in their wake 45 00:02:11,410 --> 00:02:14,190 showing as a bright line in the satellite imagery. 46 00:02:14,210 --> 00:02:18,540 These long straight tracks are extremely distinctive of this type of disturbance. 47 00:02:18,560 --> 00:02:20,060 On Mother's Day in 2008, 48 00:02:20,080 --> 00:02:23,840 several tornadoes in Georgia left a track 150 kilometers long 49 00:02:23,860 --> 00:02:27,990 and about 2 kilometers wide. 50 00:02:28,010 --> 00:02:30,320 For many tree species in the Rocky Mountain West, 51 00:02:30,340 --> 00:02:32,240 fire is a natural part of their life cycle, 52 00:02:32,260 --> 00:02:34,780 clearing space for new growth on the forest floor 53 00:02:34,800 --> 00:02:37,320 and releasing seeds from their pinecones. 54 00:02:37,340 --> 00:02:39,100 But climate change is projected to increase 55 00:02:39,120 --> 00:02:41,480 the intensity and frequency of wildfires. 56 00:02:41,500 --> 00:02:43,320 In 1988, Yellowstone National Park 57 00:02:43,340 --> 00:02:45,760 endured the largest fire ever recorded there. 58 00:02:45,780 --> 00:02:49,040 Many individual fires combined to damage 36% of the park, 59 00:02:49,060 --> 00:02:50,720 burning for several months. 60 00:02:50,740 --> 00:02:52,020 The scale of the disturbance 61 00:02:52,040 --> 00:02:55,520 is apparent in the following year's disturbance map. 62 00:02:55,540 --> 00:02:59,280 Less than 30% of the burned area re-gained forest cover by 2008. 63 00:02:59,300 --> 00:03:01,250 and the rate of recovery across Yellowstone 64 00:03:01,270 --> 00:03:02,710 has been quite variable, 65 00:03:02,730 --> 00:03:06,360 depending on the fire intensity and local conditions. 66 00:03:06,380 --> 00:03:07,600 Forests have always dealt with 67 00:03:07,620 --> 00:03:10,250 outbreaks of insects that can damage trees. 68 00:03:10,270 --> 00:03:12,680 Northern Colorado, near Rocky Mountain National Park, 69 00:03:12,700 --> 00:03:13,890 did not have severe damage 70 00:03:13,910 --> 00:03:16,710 from Mountain Pine Beetle before 2003. 71 00:03:16,730 --> 00:03:19,180 But the damage starts appearing in 2004 72 00:03:19,200 --> 00:03:20,500 in low areas, 73 00:03:20,520 --> 00:03:23,810 and spreads to higher elevations over the next few years. 74 00:03:23,830 --> 00:03:25,920 Climage change might result in more frequent episodes 75 00:03:25,940 --> 00:03:28,430 and trees less able to withstand the stress, 76 00:03:28,450 --> 00:03:30,980 but this will vary from region to region. 77 00:03:31,000 --> 00:03:32,040 78 00:03:32,060 --> 00:03:34,190 Forests are a dynamic ecosystem. 79 00:03:34,210 --> 00:03:35,910 And we need to know how fast they change 80 00:03:35,930 --> 00:03:37,740 and what is driving those changes if we ever hope 81 00:03:37,760 --> 00:03:38,830 to track how much carbon 82 00:03:38,850 --> 00:03:40,380 they're pulling out of the atmosphere 83 00:03:40,400 --> 00:03:41,920 and storing for us. 84 00:03:41,940 --> 00:03:44,730 The Landsat archive, and other remote sensing systems, 85 00:03:44,750 --> 00:03:46,230 provide the means to map and measure 86 00:03:46,250 --> 00:03:50,280 disturbance rates over the last 40 years. 87 00:03:50,300 --> 00:03:57,885