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← Nature's internet: how trees talk to each other in a healthy forest | Suzanne Simard | TEDxSeattle

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Showing Revision 17 created 02/27/2017 by Ellen.

  1. The Coast Salish people say, "We are one."
  2. [nə́c̓aʔmat ct]
  3. For thousands of years they lived it.
  4. But we didn't pay any attention.
  5. Most of us have forgotten
    that we're connected to each other,
  6. and to nature,
  7. that we are one.
  8. But nature is not some separate thing,
    but an intimate part of us.
  9. And what we do on this Earth
    ripples through our ecosystems,
  10. our web of connections.
  11. Now, the signs are undeniable:
  12. climate change,
  13. species extinctions,
  14. human suffering.
  15. We have forgotten.
  16. But for their faith, the people
    are connected through spirit to forests,
  17. and oceans and rivers
    and bears and salmon,
  18. the Coast Salish people were ignored.
  19. But truly, it does come down
    to a matter of faith,
  20. to trust and respect the relationships
    that make up the complexity of nature.
  21. But we said that's unscientific.
  22. Western science
    requires exact measurements,
  23. visible proof,
  24. statistics.
  25. But make no mistake,
  26. the Coast Salish people
    were deeply scientific.
  27. How else could they have lived here
    for over 10,000 years in such prosperity?
  28. In fact, they were more
    scientific than we.
  29. For us to look any deeper,
    that would have hampered progress.
  30. "There are trees in those forests,
    and our buildings need wood,
  31. and our printers need paper.
  32. We need to cut down the forests
    and replant those trees."
  33. Now, how do I fit into this?
  34. Well, I come from a family of loggers.
  35. And while my family
    was up on the mountainsides
  36. cutting down trees, one here, one there,
  37. I was playing in the forest below,
  38. in the places that are seen and unseen,
  39. in the trees and the logs
    and the forest floor.
  40. And I believed that fairies lived there.
  41. And their job was to live in
    and protect the forest, just like my job.
  42. But the fairies couldn't save that forest,
  43. and neither could I;
    actually, nobody could.
  44. Because the owner of the patch
    had to cut it down to feed his family.
  45. And that moment changed me forever.
  46. Actually, it motivated me.
  47. And I went to school to study forestry.
  48. I wanted to understand the mystery
    of why forests felt so powerful to me.
  49. I wanted to save forests.
  50. Ironically though, the first job I got
    coming out of forestry school
  51. was to mark old growth trees
    for clearcutting,
  52. and then to replant those clearcuts
    with fast-growing firs and pines,
  53. and to weed out the unwanted species -
    the alders, the birches, the aspens.
  54. And you know what?
  55. Well, it's because
    we considered them competitors,
  56. interfering with our profits.
  57. And I got pretty good at creating
    these shiny new monocultures.
  58. But you know,
    the questions kept piling up.
  59. Why was disease spreading
    through these plantations?
  60. Why was cutting out birch
    making the fir so sick?
  61. And I was also increasingly worried
    about the increasing rate of clearcutting.
  62. You see, I'd learned in school
    that about a century ago,
  63. that in Canada, in British Columbia,
    they developed this cutting plan
  64. to cut down all of the old growth trees
    in the working forest.
  65. I knew about it, I'd learned it in school.
  66. But it took me a long time to realize
    that the cutting was not going to stop.
  67. Nor the attitude that we could convert
    these old growth forests
  68. into nice marketable, neat plantations.
  69. It seemed to me that there was more
    to the forest than meets the eye.
  70. So, I returned to graduate school
  71. and I became fascinated
    with the underground,
  72. I wanted to understand the mystery of why
    these old growth forests were so powerful.
  73. So, I looked at this UK study,
  74. and they were examining seedlings
    growing in the laboratory,
  75. and colonized them with this fungus,
    a mycorrhizal fungus.
  76. The fungus connected
    the seedlings in a web,
  77. and they transmitted carbon
    from one seedling to the other.
  78. A mycorrhiza is literally a fungus-root.
  79. In this symbiotic association
    the fungus grows through the soil
  80. picking up nutrients and water,
    and bringing them back to the plant,
  81. and trading them
    for photosynthetic carbon.
  82. It's a symbiotic, mutualistic,
    reciprocal relationship.
  83. And most fascinating to me,
  84. these fungi could
    connect plants below ground.
  85. So, I wondered, I thought back
    to my fir forests, and I wondered,
  86. could the fungi colonizing birch
  87. actually connect with fir and protect it?
  88. So, I did some research,
    I wanted to find out.
  89. My first question
    came back to that faith thing again.
  90. Even though we can't see it,
  91. could these mycorrhizal fungi
    be connecting trees below ground?
  92. Well, it turns out
    that they can in real forests.
  93. Using DNA microsatellites,
    we uncovered this network
  94. in an old growth Douglas fir forest.
  95. In this picture, these circles
    represent Douglas fir trees.
  96. And the bigger and darker the circle,
    the bigger and older the tree.
  97. And those small,
    light circles in the middle,
  98. those are the seedlings
    growing in the understory.
  99. And these lines
    that are linking the circles,
  100. those are the interlinking
    mycorrhizal fungal highways.
  101. And you'll notice
    that the biggest, darkest circles,
  102. the biggest, oldest trees,
    are the most highly connected.
  103. So, we call these 'hub trees.'
  104. and later, more fondly,
    we started to call them 'mother trees.'
  105. Because as it turns out,
    those mother trees
  106. are nurturing the young
    seedlings in the understory.
  107. Now, this map is of only two
  108. of what we think are
    100 fungal species in the forest.
  109. Could you imagine if we'd been able
    to map all 100 species?
  110. Next I wanted to know, what might be
    flowing through this network?
  111. Well, it turns out, the very things
    that plants need to survive and grow.
  112. Things like carbon,
    and nutrients, and water.
  113. So, we use isotopes, carbon isotopes,
    and we label plants,
  114. and we were able to see the carbon
  115. transmix back and forth
    through this network,
  116. like messages transmitting
    through the internet.
  117. And when one seedling is under stress,
    if it's small, or shaded,
  118. or nutrient poor, or senescing,
    the other plant sends more carbon.
  119. We figured out that it follows
    what's called a source-sink gradient.
  120. From a robust source plant
    like an illuminated birch tree
  121. to a needful sink plant
    like an understory fir tree,
  122. and all this without
    harming the source plants.
  123. The next thing we wanted to know was,
  124. so this happens, but what does
    it really matter in forests?
  125. Well, it turns out
    if you shade one of the plants,
  126. if Douglas fir's shaded in the understory,
    birch will send ten percent of its carbon,
  127. and that's a lot of carbon.
  128. That's enough for Douglas fir
    actually to make seeds.
  129. Now, we haven't figured out
    precisely what the amounts mean,
  130. but we do know that this transfer
    increases their survival and growth,
  131. and health of the seedlings
    growing in the understory.
  132. Now, I published this work
    in some pretty good journals.
  133. This particular article struck a chord.
  134. Lots of people were enthused.
  135. In fact, there is a whole bunch
    of new research all around the world
  136. that was inspired by this paper.
  137. But there were also critics
    who tried to discredit my work.
  138. In fact, there were
    a lot of papers written,
  139. keynote addresses given,
  140. press releases.
  141. And back home,
  142. a professional ethics letter
    was actually put on my file.
  143. And my work was called
    "a dog's breakfast."
  144. Now, I know that you know
    that this kind of intimidation
  145. is actually not that uncommon
    with breakthrough science,
  146. especially if it challenges
    the status quo.
  147. Knowing this, this didn't stop me.
  148. I knew that my science
    was sound and rigorous,
  149. and I knew that one day it could change
    the way we view the environment.
  150. So, really motivated,
    I returned to my original question,
  151. because I still
    hadn't quite answered it yet.
  152. And I wondered,
    could these webs, these networks,
  153. serve as more than just avenues
    of exchange of carbon and nutrients
  154. and water.
  155. Could a tree
    that's under stress, diseased,
  156. actually benefit
    from the health of its neighbors?
  157. Could birch be helping fir?
  158. So, I did some more experiments,
    and it turns out, it does.
  159. When Douglas fir
    is under stress or disease,
  160. it sends warning signals to its neighbors,
  161. and the neighbors respond by increasing
    production of their defense enzymes,
  162. and they're more resistant to disease.
  163. And if that neighbor is a birch tree,
  164. the fir benefits from
    the antibiotic-producing bacteria
  165. that are associated
    with this shared network.
  166. It's like a public immunization system.
  167. And I wondered, could there be more
    than defense signals moving?
  168. Well, it turns out that trees
    can actually recognize,
  169. transmit messages to their relatives.
  170. A mother tree can recognize
    whether seedlings in her neighborhood
  171. are her kin or strangers.
  172. She sends more carbon
    to kin seedlings than to strangers.
  173. And if the mother tree is injured,
  174. she sends even more carbon
    to her kin seedlings.
  175. It's as though she's passing her energy,
    her legacy, to the next generation.
  176. Now, when I look at all this together,
  177. it's as though these trees
    are sharing their deepest secrets.
  178. This is breakthrough stuff.
  179. It's pretty exciting.
  180. You know, at the time,
    there were actually many articles written,
  181. Popular Science,
  182. documentary films,
  183. the word was getting out,
    and I was really, really excited.
  184. But I got cancer.
  185. And that was really awful.
  186. But you know,
    the beautiful thing about this
  187. is that it re-connected me with my people.
  188. My people, my family, looked after me.
  189. They held me.
  190. They helped me up the stairs.
  191. They cooked my meals.
  192. They looked after my children.
  193. They saved me.
  194. And back in the hospital,
    I made even more connections,
  195. strong ones,
  196. with other women fighting breast cancer.
  197. And we were really afraid,
  198. and we cried.
  199. But we also laughed.
  200. We still do every day.
  201. We've become so tight,
    we're like this tapestry
  202. that's knit together in a tight weave.
  203. When one of us stumbles or bends,
    the others are right there to pick her up.
  204. What I've learned through all this,
  205. is what my forests
    have been trying to tell me all along -
  206. that these connections
    are crucial to our well-being.
  207. They're not easily seen,
  208. but they're real.
  209. And you know what? I'm living proof.
  210. And I'm really grateful.
  211. (Applause)
  212. Thank you.
  213. Now that I'm strong and healthy again,
    I've returned to my science,
  214. and I'm asking other questions.
  215. My first, and the most important
    question to me is,
  216. what can our discoveries tell us
    about how to deal with our biggest threat?
  217. Climate change.
  218. Yeah, climate change is no hoax.
  219. In fact, we can't kid ourselves,
  220. there is no fancy engineering
    that's going to get us out of this mess.
  221. What my discoveries have shown me,
    is that the answer, the solution,
  222. lies in our relationship with nature.
  223. And in doing this research,
    I went to the Aboriginal people.
  224. I'm doing my research
    with Aboriginal people
  225. who are, as you know,
    dependent on the salmon,
  226. have a long relationship
    of stewardship of the salmon
  227. which then helps with their livelihood,
    it is crucial to their livelihood.
  228. So, in the fall, when the salmon
    are spawning in the rivers,
  229. the bears come down to the river,
  230. and the wolves, and they feed
    on the salmon in the spawning rivers,
  231. and they carry the salmon
    up into the forest.
  232. And underneath the big, old mother trees,
  233. under the sheltering crowns
    of the mother trees,
  234. they feed on the salmon.
  235. And in the fall, the leftovers decay
    and seep into the ground.
  236. And we think
  237. that the big mycorrhizal networks
    of those mother trees
  238. soak up that nitrogen.
  239. And scientists have discovered
    traces of salmon nitrogen
  240. in the tree rings,
    stored there for centuries.
  241. And what we're going to do this summer
    is go back to these forests,
  242. and we're going to trace whether nitrogen
    - and we think this is happening -
  243. moves from mother trees
    to their neighbors,
  244. from tree to tree to tree,
    deep into the forest.
  245. And we think this is tied
    to the health of the forest,
  246. which of course is tied
    to the health of the rivers,
  247. which of course is linked to the salmon,
    and the health of the salmon populations,
  248. which of course, feeds back to the oceans,
    and comes back to us, the people.
  249. Now, this circle of life,
  250. what our Aboriginal ancestors
    have called 'reciprocity,'
  251. is the trading of mutual respect.
  252. And this is a really good example
    of what scientists are calling
  253. 'complex adaptive systems.'
  254. Now look, forests
    are built on relationships.
  255. In a healthy forest, everything
    is connected, and communicating.
  256. Here, these nodes represent the species.
  257. And they're constantly
    relating to each other.
  258. And it's out of their interactions
    that emerges what scientists are calling
  259. 'complex adaptive behaviors,'
  260. or higher system level properties.
  261. Things like resilience and health,
  262. the cycling of clean air and clean water.
  263. But you know, in modern society,
    we view ourselves separate from this,
  264. somehow entitled, or superior,
  265. or at the minimum, we take it for granted.
  266. But the thing is,
    when we take out key parts,
  267. like the grizzly bears,
  268. and we trash the salmon populations,
  269. these systems rapidly degrade
  270. into what we're calling
    'wicked stable states.'
  271. Now, this is not somewhere we want to go.
  272. Wicked stable states are unpredictable,
  273. they're contradictory.
  274. When you try to fix one problem,
    another problem shows up over here.
  275. And the way things are going, right now,
  276. with our forests
    dying from climate change,
  277. which feeds back to more climate change,
  278. this is happening really fast.
  279. But here's the beautiful thing:
  280. It's precisely because
    they're complex adaptive systems
  281. poised for change,
  282. that we can change this trajectory
    from negative to positive.
  283. Here's how we do this.
  284. First, we've got to re-imagine ourselves
    as part of this network.
  285. Imagine yourself listening
    to all the other creatures.
  286. We can tap into that below-ground network
    and become part of the conversation.
  287. If we'd done this, we would never
    have cut birch out of those forests,
  288. the Douglas fir forests,
  289. because we would have known it undermines
    the resilience of the forest.
  290. But we're still doing that.
  291. But I'm still very hopeful,
  292. because I know that once we tap into
    this complex adaptive system,
  293. into our role in it,
  294. we can change our thinking,
    we can change our behavior.
  295. We can become part of this great system.
  296. Remember when birch
    was sending nutrients to fir,
  297. and fir was sending them
    back to birch, remember that?
  298. Well, this just proves
    that in ecosystems, there is no bigotry,
  299. there's only reciprocity,
  300. only mutual respect.
  301. Just like in my cancer support network.
  302. That's what we practice.
  303. So finally, thirdly,
  304. I know that once we understand
  305. that we are deeply part of nature,
  306. really part of nature,
  307. not separate,
  308. that we can become
    part of the great strengthening,
  309. that positive trajectory.
  310. We have to stop treating nature
    as our shopping mall,
  311. and once we do that,
    we can change the arc of the future.
  312. Once, I thought that fairies
    connected and protected the forest,
  313. and now with my science,
    I know I wasn't that far off.
  314. (Laughter)
  315. Using science, I've shown that precisely,
    these unseen connections exist,
  316. just like the Coast Salish
    have been telling us all along.
  317. They've shown, the science has shown,
    that everything is connected
  318. and communicating,
  319. with respect and reciprocity.
  320. And out of this comes balance
    in our communities and our ecosystems.
  321. And it's based on principles like kinship,
  322. respect of elders,
  323. and this gives rise
    to complexity and adaptability.
  324. And out of this, of course,
    we have resilience.
  325. Resilience to deal with things
    like climate change.
  326. So, I want to leave you
    with one final, hopeful message.
  327. I know, based on my experience,
    and in my science,
  328. that you, too, can own this,
  329. that we are one.
  330. Thank you very much.
  331. (Applause)