BBC.The.Green.Planet.3of5.Seasonal.Worlds.1080p.HDTV.x265.AAC.MVGroup.org.eng Movie Subtitles

1 00:00:50,200 --> 00:00:53,320 This is the boreal forest... 2 00:00:58,440 --> 00:01:01,000 ..the largest forest on Earth. 3 00:01:02,680 --> 00:01:06,320 750 billion trees... 4 00:01:09,160 --> 00:01:12,520 ..smothered by snow throughout the winter. 5 00:01:17,640 --> 00:01:22,360 This is the northernmost boundary of an extraordinary world. 6 00:01:26,200 --> 00:01:30,840 I'm standing at the edge of the Arctic Circle. 7 00:01:30,840 --> 00:01:35,320 To the north of me lies a land dominated for most of the year 8 00:01:35,320 --> 00:01:37,600 by snow and ice. 9 00:01:37,600 --> 00:01:41,280 3,000 miles to the south - the tropics, 10 00:01:41,280 --> 00:01:45,320 bathed the year round in warm sunshine. 11 00:01:45,320 --> 00:01:48,960 And in between, a very different world, 12 00:01:48,960 --> 00:01:52,400 dominated by relentless change. 13 00:01:58,320 --> 00:02:02,320 An endless cycle of four distinct seasons, 14 00:02:02,320 --> 00:02:04,720 each with its own challenges. 15 00:02:06,200 --> 00:02:09,000 The short, freezing days of winter 16 00:02:09,000 --> 00:02:12,880 give way to the urgent awakening of spring. 17 00:02:15,720 --> 00:02:19,280 And the long, hot days of summer 18 00:02:19,280 --> 00:02:22,440 yield to the cooling of autumn. 19 00:02:26,920 --> 00:02:29,760 Opportunities will be brief. 20 00:02:37,280 --> 00:02:39,360 To survive these extremes, 21 00:02:39,360 --> 00:02:43,600 plants have not only g***t to be hardy and resilient, 22 00:02:43,600 --> 00:02:47,080 but many of them have developed special strategies 23 00:02:47,080 --> 00:02:51,320 in order to meet the demands of this seasonal world. 24 00:02:53,560 --> 00:02:57,840 To succeed, they must get their timing just right. 25 00:03:00,880 --> 00:03:04,480 For months now, this world has been asleep. 26 00:03:05,720 --> 00:03:08,160 But change is coming. 27 00:03:23,400 --> 00:03:26,400 Spring is on its way. 28 00:03:49,400 --> 00:03:53,640 In Canada, the forests are starting to stir. 29 00:03:55,920 --> 00:03:59,360 Throughout the winter, the sugar maples here 30 00:03:59,360 --> 00:04:03,600 have kept stores of nutrients ready for this moment. 31 00:04:06,440 --> 00:04:09,720 Now, as temperatures start to rise, 32 00:04:09,720 --> 00:04:13,280 those nutrients must be brought up from the roots. 33 00:04:20,880 --> 00:04:23,280 Sap is on the rise. 34 00:04:28,800 --> 00:04:31,640 Fuel for new green growth. 35 00:04:42,840 --> 00:04:45,440 But just as growth reaches full speed... 36 00:04:47,000 --> 00:04:49,080 ..robbers arrive. 37 00:05:08,880 --> 00:05:11,440 A sap sucker. 38 00:05:11,440 --> 00:05:15,720 A thief in search of maple syrup. 39 00:05:33,560 --> 00:05:36,440 The tree can tolerate hundreds of wounds. 40 00:05:43,840 --> 00:05:47,600 But if they completely encircle the trunk, 41 00:05:47,600 --> 00:05:50,880 the tree will eventually die. 42 00:05:58,080 --> 00:06:01,880 The sap sucker's break-in hasn't gone unnoticed. 43 00:06:11,000 --> 00:06:17,480 Hummingbirds, squirrels and insects 44 00:06:17,480 --> 00:06:20,720 all invade the sap sucker's territory, 45 00:06:20,720 --> 00:06:22,840 trying to steal a meal. 46 00:06:27,000 --> 00:06:30,040 But unwittingly, they help the tree. 47 00:06:36,000 --> 00:06:38,480 Time spent chasing the competition... 48 00:06:40,280 --> 00:06:43,520 ..means less time to drill new holes. 49 00:07:13,360 --> 00:07:17,160 The tree gets a chance to repair its wounds. 50 00:07:19,400 --> 00:07:22,280 And the sap can rise freely again. 51 00:07:29,800 --> 00:07:34,880 So this year, at least, the tree will once more produce its leaves. 52 00:07:39,360 --> 00:07:42,200 Hundreds of miniature solar panels 53 00:07:42,200 --> 00:07:44,400 that collect energy from the sunlight. 54 00:07:48,080 --> 00:07:52,320 Each leaf is covered by millions of microscopic pores. 55 00:07:53,520 --> 00:07:55,360 Stomata. 56 00:07:58,120 --> 00:08:00,960 They take in carbon dioxide... 57 00:08:02,720 --> 00:08:05,600 ..and release oxygen and water vapour 58 00:08:05,600 --> 00:08:09,160 in a process that produces high-energy fuel. 59 00:08:21,640 --> 00:08:24,600 All the trees here can now use that fuel 60 00:08:24,600 --> 00:08:27,120 to grow over the coming months. 61 00:08:46,440 --> 00:08:51,440 As spring proceeds, the power of the sun increases. 62 00:08:55,120 --> 00:08:57,360 On river banks across Europe, 63 00:08:57,360 --> 00:09:02,800 many plants have been lying dormant underground, 64 00:09:02,800 --> 00:09:05,440 waiting for the earth to warm. 65 00:09:11,920 --> 00:09:14,560 And now a race begins. 66 00:09:21,760 --> 00:09:26,600 Among the first to start are nettles - the sprinters. 67 00:09:32,280 --> 00:09:36,120 Then, only just behind, come the brambles. 68 00:09:37,560 --> 00:09:41,240 They're much more aggressive and have backward-pointed hooks 69 00:09:41,240 --> 00:09:44,040 with which to scramble over their rivals. 70 00:09:46,880 --> 00:09:49,920 Last to come - the climbers. 71 00:09:53,200 --> 00:09:55,520 Hops... 72 00:09:55,520 --> 00:09:57,480 ..and bryony. 73 00:10:01,200 --> 00:10:04,160 They lasso their way towards the light. 74 00:10:33,440 --> 00:10:38,160 Soon, every inch of space and every patch of light has been claimed. 75 00:10:41,600 --> 00:10:43,480 But hidden in the shadows, 76 00:10:43,480 --> 00:10:47,320 another plant has been waiting to make its move. 77 00:10:56,800 --> 00:10:59,920 This... 78 00:10:59,920 --> 00:11:01,920 ..is dodder. 79 00:11:08,160 --> 00:11:10,120 A hunter... 80 00:11:11,840 --> 00:11:14,280 ..with an exceptional sense of smell. 81 00:11:21,480 --> 00:11:24,920 Moving swiftly, it searches for its prey. 82 00:11:28,280 --> 00:11:31,120 It detects the scent of a young nettle. 83 00:11:50,440 --> 00:11:53,880 The dodder punctures the nettle's stem 84 00:11:53,880 --> 00:11:56,440 and s***s out the nutritious sap. 85 00:12:00,320 --> 00:12:03,120 And it doesn't stop at just one victim. 86 00:12:06,280 --> 00:12:09,080 With its energy supply assured, 87 00:12:09,080 --> 00:12:11,120 it multiplies. 88 00:12:20,080 --> 00:12:23,680 It's a parasite with an insatiable appetite. 89 00:13:25,920 --> 00:13:31,520 But remarkably, its victims can now exploit the dodder... 90 00:13:33,720 --> 00:13:36,440 ..when other springtime enemies appear. 91 00:13:40,480 --> 00:13:42,520 Caterpillars. 92 00:13:53,760 --> 00:13:57,360 When under attack, a leaf sends out a signal 93 00:13:57,360 --> 00:14:01,080 telling the rest of the plant to start building defences... 94 00:14:04,080 --> 00:14:07,960 ..foul-tasting toxins that deter the caterpillars. 95 00:14:10,960 --> 00:14:13,440 In an extraordinary twist, 96 00:14:13,440 --> 00:14:16,720 the stems of the dodder interconnecting the plants 97 00:14:16,720 --> 00:14:20,520 are now being used as lines of communication 98 00:14:20,520 --> 00:14:24,960 to relay these warning signals from plant to plant. 99 00:14:31,520 --> 00:14:35,560 They respond by producing their own protective chemicals. 100 00:14:39,640 --> 00:14:44,880 Eventually, the whole river bank becomes one huge defensive network. 101 00:14:46,400 --> 00:14:50,360 And the one-time rivals are now better off together. 102 00:15:11,920 --> 00:15:17,360 The first warm days of spring encourage some plants to flower 103 00:15:17,360 --> 00:15:19,800 and get ahead of the competition... 104 00:15:21,480 --> 00:15:25,920 ..creating beautiful displays throughout the seasonal world. 105 00:15:28,800 --> 00:15:32,000 From the spectacular cherry blossoms of Japan... 106 00:15:35,280 --> 00:15:39,080 ..to the goldfield flowers of California. 107 00:15:43,400 --> 00:15:46,160 But spring flowering is risky. 108 00:15:46,160 --> 00:15:48,880 If they flower too early, it may not be warm enough 109 00:15:48,880 --> 00:15:51,280 for pollinating insects to be active. 110 00:15:53,320 --> 00:15:57,400 But the common daisy gives them every opportunity. 111 00:16:01,280 --> 00:16:05,160 The warmer the flowers are, the more attractive they are - 112 00:16:05,160 --> 00:16:09,560 and they have a remarkable strategy in order to maximise this. 113 00:16:11,640 --> 00:16:15,120 They were closed up tightly throughout the night 114 00:16:15,120 --> 00:16:17,520 as a protection against the elements. 115 00:16:17,520 --> 00:16:21,160 But once they feel the warmth and the light of the sun, 116 00:16:21,160 --> 00:16:23,200 they spring into action. 117 00:16:37,640 --> 00:16:40,280 It's a behaviour called heliotropism. 118 00:16:42,280 --> 00:16:46,160 They turn to keep facing the sun, 119 00:16:46,160 --> 00:16:48,960 absorbing as much heat as they can. 120 00:17:05,680 --> 00:17:09,360 This is a thermal camera, 121 00:17:09,360 --> 00:17:14,720 and it will tell me the difference between the surrounding temperature 122 00:17:14,720 --> 00:17:18,840 and the temperature in the centre of a daisy flower. 123 00:17:18,840 --> 00:17:22,080 The surroundings - 12 degrees. 124 00:17:23,840 --> 00:17:25,960 In the centre of a flower... 125 00:17:27,600 --> 00:17:29,800 ..21. 126 00:17:31,840 --> 00:17:37,280 Pollinators such as bees and wasps prefer the warmed-up flowers 127 00:17:37,280 --> 00:17:40,160 because they can get a share of the heat for themselves. 128 00:17:42,080 --> 00:17:46,240 As a...