but there comes a tipping point,  但这样就会达到森林承受极限了，

because hub trees are not unlike rivets in an airplane.  因为森林里的中心树就像是飞机里的铆钉。

You can take out one or two and the plane still flies, but you take out one too many, 你卸下一两个铆钉的话飞机还能飞，但是如果你一次卸下太多，

or maybe that one holding on the wings, and the whole system collapses. 或是仅仅卸下固定机翼的那一颗铆钉，整个系统就要崩溃了。

So now how are you thinking about forests? Differently?  那么现在你们对森林的看法是怎样的了？有些改变了吧？

Cool. I'm glad. 真棒。我太高兴了。

So, remember I said earlier that I hoped that my research,  你们还记得吧，我之前说过我希望我的研究，

my discoveries would change the way we practice forestry.  我的探索可以改变一些我们的林业实践的方式。

Well, I want to take a check on that 30 years later here in western Canada.  我想在30年后在西加拿大的这个地方做个检测。

This is about 100 kilometers to the west of us, just on the border of Banff National Park. 这里大概是在西边距我们100公里的地方，就在班夫国家公园的边上。

That's a lot of clear-cuts. It's not so pristine. 在那里到处都发生着皆伐。现在不是原始社会了。

In 2014, the World Resources Institute reported that Canada in the past decade 2014年，据世界资源研究所报道，加拿大在过去十年中的

has had the highest forest disturbance rate of any country worldwide, and I bet you thought it was Brazil. 森林破坏率已经达到了世界最高，比任何一个国家都高，我打赌你现在肯定想到了巴西。

In Canada, it's 3.6 percent per year.  在加拿大，森林破坏率是每年3.6%。

Now, by my estimation, that's about four times the rate that is sustainable.  据我推算，这大概是可持续发展的砍伐率的四倍了。

Now, massive disturbance at this scale is known to affect hydrological cycles, degrade wildlife habitat, 大规模高强度的砍伐已经严重影响到了水循环，破坏了野生动物的栖息地，

and emit greenhouse gases back into the atmosphere, which creates more disturbance and more tree diebacks. 而且又向大气中释放了很多温室气体，这也会使更多的树木枯死，造成更严重的破坏。