17-1-6 进入森林请小心，科学告诉你“树精姥姥”真的存在！Trees talk to each other

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Suzanne Simard: Howtrees talk to each other

Speaker’s biography:

A professor offorest ecology at the University of British Columbia's Department of Forest andConservation Sciences in Vancouver, Suzanne Simard studies the surprising anddelicate complexity in nature. Her main focus is on the below-ground fungalnetworks that connect trees and facilitate underground inter-tree communicationand interaction. Her team's analysis revealed that the fungi networks movewater, carbon and nutrients such as nitrogen between and among trees as well asacross species.

Section 1:

Imagine you'rewalking through a forest. I'm guessing you're thinking of a collection of trees.Yes, trees are the foundation of forests, but a forest is much more than whatyou see, and today I want to change the way you think about forests. You see,underground there is this other world, a world of infinite biological pathwaysthat connect trees and allow them to communicate and allow the forest to behaveas though it's a single organism. It might remind you of a sort ofintelligence.

Trees in realforests might also share information below ground. It turns out at that time ofthe year, in the summer, that birch was sending more carbon to fir than fir wassending back to birch, especially when the fir was shaded. And then in laterexperiments, we found the opposite, that fir was sending more carbon to birchthan birch was sending to fir, and this was because the fir was still growingwhile the birch was leafless.

So it turns outthe two species were interdependent, like yin and yang. I knew I hadfound something big, something that would change the way we look at how treesinteract in forests, from not just competitors but to cooperators.

Vocabulary:

Organism,interdependent

Section 2:

How were paperbirch and Douglas fir communicating? Well, it turns out they were conversingnot only in the language of carbon but also information. The web is so densethat there can be hundreds of kilometers of mycelium under a singlefootstep. And not only that, that mycelium connects different individuals inthe forest, and it works kind of like the Internet.

You see, likeall networks, mycorrhizalnetworks have nodesand links. The biggest, darkest nodes are the busiest nodes. We call those hubtrees, or more fondly, mother trees, because it turns out that those hub treesnurture their young, the ones growing in the understory. In a single forest, a mother tree canbe connected to hundreds of other trees.

Mother treescolonize their kin with bigger mycorrhizal networks. They send them more carbon below ground.They even reduce their own root competition to make elbow room for theirkids. When mother trees are injured or dying, they also send messages of wisdomon to the next generation of seedlings. So trees talk. Through back and forthconversations, they increase the resilience of the whole community.

Vocabulary:

Mycelium, elbow room, resilience

Section 3:

So let's comeback to the initial point. Forests aren't simply collections of trees, they'recomplex systems with hubs and networks that overlap and connect trees and allowthem to communicate, and they provide avenues for feedbacks and adaptation, andthis makes the forest resilient. You see, you can take out one or two hubtrees, but there comes a tipping point, because hub trees are not unlikerivets in an airplane. You can take out one or two and the plane still flies,but you take out one too many, or maybe that one holding on the wings, and thewhole system collapses.

So I want tocome back to my final question: instead of weakening our forests, how can wereinforce them and help them deal with climate change? First, we all need toget out in the forest. We need to reestablish local involvement in our ownforests. Second, we need to save our old-growth forests. These are the repositories of genes and mother trees and mycorrhizal networks. And third, when we do cut,we need to save the legacies, the mother trees and networks, and the wood, thegenes, so they can pass their wisdom onto the next generation of trees so theycan withstand the future stresses coming down the road. And finally, wehave to give Mother Nature the tools she needs to use her intelligence toself-heal.

Vocabulary:

tipping point,repository, withstand