- 6 weeks ago
Forest conservation scientist Dominick DellaSala joins WIRED to answer the internet’s burning questions about trees. What did ancient forests look like? What do tree rings really prove? Do rainforests create rain or does rain create rainforests? Answers to these questions and many more await on Forest Support.
Category
🤖
TechTranscript
00:00I'm Dominic Della Sala, forest ecologist.
00:02Let's answer your questions from the internet.
00:04This is forest support.
00:11At Unruly Obnoxious ask,
00:13I wish there actually was a mother tree
00:15like they showed in Avatar.
00:17I watched that movie too, and I was fascinated by it.
00:20The mother tree was the central tree
00:22that connected everything in ecosystems
00:25in very vivid colors.
00:26And I had a similar experience
00:29when I was in the Borneo rainforest.
00:31The fungi were all lit up in bioluminescent colors.
00:35You didn't need a flashlight
00:36to walk through that rainforest that night
00:39because it was so colorful.
00:41And those trees are very unique to the Borneo rainforest.
00:45When they are cut down, they don't come back
00:47because they have very specific pollinator relationships.
00:51So Gaffer9 asks,
00:53how do forests regenerate after fires naturally?
00:56Seeds blown in from outside the fire zone.
00:58One of the fascinating things about forests is after a severe fire that kills all the trees,
01:04it's not an ecological catastrophe.
01:07In the ashes, they will release cones like the serotonous cones of lodgepole pine
01:13that need intense heat to burst open their seed cones.
01:16There are trees that will sprout after a fire, like a madrone.
01:21They will take advantage of this nutrient-rich environment to release their seeds in a seed rain
01:27so that their progeny will develop into the next forest.
01:31So life and death are both important in a forest and are both needed for the healthy systems to function.
01:39Leo Pei asks, what did ancient forests look like?
01:43If we go back in time to the period of the dinosaurs,
01:46trees were a lot different.
01:48They were gymnosperms.
01:49They weren't angiosperms.
01:50So the flowering plants had not really developed at that time.
01:54The monkey puzzle tree is a good example of that.
01:57It has all kinds of needles on it.
01:59The story is that a monkey looked at the tree and was puzzled by how it was going to climb
02:04that tree
02:05with all those needles on it.
02:06That perfect day to play, how do trees access the internet on a camping trip?
02:11They log into the wood wide web.
02:14Well, there is some reality to that, even though it's a funny corny joke.
02:18Trees are connected through their mycorrhizae networks.
02:22These are fungi that attach themselves to the roots of plants and allow them to communicate through chemical interactions.
02:29There has been some really interesting work done by scientist Susan Cimarrod,
02:33where she actually described connections on the root systems of plants
02:38that allowed them to communicate chemically to one another.
02:42And the closer the relationships between mother and progeny,
02:46the more connected the underground network was in that fungal system.
02:51So trees have a lot of different ways to communicate.
02:54When there is an infestation coming, they will release pitch that will trap insects
03:01that are landing on the surface of the tree trunk.
03:05And that will be a signal to other trees in the forest that they're under attack
03:09so that they can prepare their defenses.
03:12Richard Biss asks,
03:14Why do we have so many forest fires in California?
03:17It seems like we have a lot there.
03:18Fires have been burning in California for millennia.
03:21If you're living in Southern California, chances are you're experiencing fires during high winds,
03:26the Santa Ana winds, that will propagate fires through chaparral, shrubby, grassland areas.
03:33In other areas of the state, you're going to get fires in forests that, by and large,
03:39are very beneficial to these ecosystems.
03:41They need fires to rejuvenate themselves and to allow their seeds to develop into larger trees
03:49and forest vegetation over time.
03:51There are unfortunate consequences when fires spill over into communities.
03:56And there are ways that we can prepare for that.
03:59The way to do that is to make sure that your roof is a composite or metal that's not going
04:04to burn.
04:05Make sure that your open vents for ventilation have proper screens on them.
04:10Make sure that you're clearing a defensible space around the home itself out to 50 to 100 feet
04:17so that your flames will not carry from the wild areas onto the roof and get into the vents.
04:24Zentrier asks,
04:26My tree exploded. What is going on?
04:28There is a tree that sort of explodes.
04:31It's called the sandbox tree and its leaves and its spine are toxic to humans.
04:36And when it releases its seeds, those seeds can be projected at high velocities
04:41and cause a lot of damage to people and animals.
04:45Twitmo Pro says,
04:46What the do you know about forest management?
04:49Trump is exactly right about cleaning up debris and fallen trees from the forest floor.
04:54It's really very simple.
04:56Well, no, it's not simple.
04:58And Trump is not right in cleaning up the forest floor.
05:02This is not just going out there with some rake on the forest floor to get the leaves off the
05:07ground.
05:07What Trump is doing is clear-cut logging that actually will make fire more prevalent in those forests.
05:14There's about 760 million acres of forest in the United States, most of which are under private ownership.
05:21There's about 190 million plus acres of the national forest system.
05:25They are not all protected like national parks.
05:28Most of them are open for a whole variety of uses, including logging.
05:32When you log a forest, a lot of that logging slash, the twigs, the leaves are left on the ground.
05:38Some of it's treated, but a lot of it's left on the ground.
05:41And that provides the kindling for these fast-moving fires.
05:45So the Trump executive logging orders, which is directing the federal agencies to do more logging,
05:52is actually going to make them more prone to forest fires by taking out the big old trees
05:57that are the most fire-resistant parts of the forest and leaving a lot of flammable logging slash behind.
06:04Eric Hoven asked, what do tree rings really prove?
06:08Well, tree rings are a living record of the tree's growth patterns.
06:12So this tree is about 30 years old when I count up all the rings.
06:16The tighter the rings are on this, it means that the conditions for growth during that year weren't as good.
06:22It might have been a drought.
06:24The wider the rings means that the tree was doing better, the conditions were more favorable,
06:29and the living part is the outermost section that has the xylem and the flolum,
06:35which is the tree's circulatory system that is passing nutrients to different parts of the tree and water.
06:42The other thing we can note from this is the bark of the tree.
06:45So the bigger the tree, the more bark it will lay down, the more insulated it is from most forest
06:51fires.
06:52If there was a forest fire, there will be scars that have been laid down across the ring
06:57so that you can actually determine what year the fire was occurring in that affected this tree.
07:04So Puntit Review asks, is Smokey the Bear full of ?
07:08Nine out of ten wildfires are caused by humans.
07:11Hashtag smoke this.
07:12When you add up all the fires across the nation, roughly nine out of ten have a human cause to
07:19them,
07:19and that's associated with high road densities, population centers that have access to wild areas
07:25that can cause a fire accidentally.
07:27Let me address the second part of this question.
07:29Smokey Bear would appear in posters and logos,
07:33and his motto was, only you can prevent forest fires.
07:38And it was really targeting campfires, but then it got blown out of proportion
07:42and became the symbol for the forest service policy to put out every fire start by 10 a.m. the
07:48next day,
07:49which is destructive and catastrophic to ecosystems that need fire
07:53to balance out their growth and rejuvenation and aging processes.
07:59Harry Awareness asks, how much of a dent in climate change will Mr. Beast's 20 million trees project make?
08:06Planting trees is a good idea in the right places, but it is not going to make as big of
08:11a dent
08:12in the climate crisis as protecting our existing forests, especially the old growth forest.
08:19So an old growth forest is a biological cathedral.
08:23The tall, wide, big trees in those forests are really important habitat,
08:28and they also represent the accumulation of atmospheric carbon that you see in their trunks.
08:35There's no replacing those trees by planting the little seedlings that will take hundreds of years
08:40to start accumulating that carbon.
08:43At Oliver Hangout asks, I have to do a presentation in biology,
08:47and I have to present nine slides about the boreal forest.
08:52Like, what the is a boreal forest?
08:54They are cool forests found in places that are very cold.
08:59As you can see, the green area on this illustration, just below the Arctic Circle,
09:04is where these forests occur.
09:06They have all kinds of different tree species growing in some extreme conditions,
09:11where we get a lot of snowfall.
09:12You'll get conifer trees, like pines, and you'll get some hardwoods, like aspens.
09:18They are the places where most of our migratory birds wind up during the breeding season.
09:24The boreal will support up to a billion birds during the summertime.
09:28There are other kinds of forests that exist around the planet.
09:31The next latitudinal zone are the temperate regions.
09:34In the United States, most of our forests are temperate.
09:38If you go to the Appalachian Trail or the Pacific Crest Trail,
09:42and you're hiking through those areas in the forest, you're in a temperate zone.
09:46The temperate forests have all kinds of really interesting tree species.
09:50They're a mixture of oaks, conifers, and aspens.
09:54It's really quite biodiverse.
09:57And there's a sub-portion of the world's temperate forests that are actually temperate rainforest.
10:03An example would be the Olympic Peninsula in Washington or the Tongass rainforest in Alaska.
10:09The trees are enormous.
10:11They grow to over 200 feet tall.
10:13They are as wide as this table.
10:15Those rainforests are absorbing so much carbon and giving so much habitat to the salmon
10:21that will use those rainforests.
10:24They'll come up the streams and spawn, and then their carcasses will be eaten by eagles.
10:29The eagles will poop out their remains, and that will be fertilizer for the rainforest trees.
10:35Now, if we get further south into the Southern Hemisphere, now we're talking tropical rainforests,
10:40which have all kinds of unique tropical species in a very wet and hot environment.
10:46If we go over to Europe, where there are only small fragments of rainforests, like in the UK,
10:53the trees are much shorter.
10:54They only grow to maybe 30 feet tall instead of 300 feet tall, but they're still rainforests
11:01because they're blanketed by rainy conditions.
11:04They're just different in terms of the height of trees and the type of tree species there.
11:09Here's a question from Quora.
11:11Is it true that there is a forest that is a single living organism?
11:15Arguably, forests are interconnected superorganisms.
11:19If you look at an aspen forest, it could have originated from a single aspen tree
11:24that would send out its below-ground runners, its suckers, that would then come up through the soil
11:31and be an entire group of trees from the single organism.
11:36Spontaneously Peaked asked, how do forests return so quickly to the Northeastern United States,
11:41which had been almost completely deforested?
11:44The Northeastern forests were almost completely deforested over a hundred years ago,
11:49and that led to almost the entire elimination of old-growth virgin ancient forests.
11:55However, there's been a century or so of no logging activity in some of those forests that are now
12:01maturing and returning to older characteristics.
12:05So most of the forests that you get in the Adirondacks or the Appalachia region
12:10had been logged over a century ago.
12:13So they're really secondary forests, and that's the beauty of forests.
12:17If we allow them to recover, if we don't log them the second time through,
12:21they will develop those attributes that make them uniquely old.
12:26Private Tumbleweed asked, is it bull that there are more trees on the planet right now
12:31than there has ever been in all of history?
12:34Well, yeah, it is bull .
12:36We've been deforesting the planet for thousands of years.
12:39The scale of that deforestation has increased, and so currently we're down to about a third of what
12:45the forests were on the planet before all of this widespread deforestation had taken place.
12:50And of that group, only about 28% are considered primary forests.
12:56Those are forests that have never been logged.
12:59So that's why you can't just say we're planting trees and just counting that there are more trees
13:04we planted now than ever in history.
13:07It's because the quality is really important.
13:10You can't plant an old-growth forest.
13:12It takes centuries for those forests to develop.
13:16Matthew E. Gunter asks, do rainforests create rain or does rain create rainforests?
13:23It's actually both.
13:24Trees are remarkable because they take in rain and use it, and then they go through evapotranspiration,
13:32where water evaporates, returns to the atmosphere, and becomes the water cycle again.
13:38So the two are connected.
13:40And so when rainforests are cut down, they can actually change the regional climate.
13:45So when that rainforest is removed, we see more droughts.
13:49C. Hayes 55 asked, are they still burning the Amazon rainforest down?
13:54So this is a pretty general map of the Amazon rainforest.
13:58You can see in green color areas that are still intact.
14:02They haven't been logged.
14:03And then you see these other areas in orange that represent deforestation that has occurred.
14:09Rainforests are being cut down, burned, and cattle are then grazed over the area.
14:14And that then triggers these droughts that we're now seeing in the Amazon basin
14:19because we don't have the return of water to the hydrosphere and the atmosphere.
14:23So if that keeps happening, the Amazon will eventually flip into a drought-stricken savanna
14:30and lose all the rainforest benefits.
14:32That could happen within the next couple of decades,
14:35depending on the speed at which climate change progresses across the planet.
14:40At JamesRuss42, without cheating, in what country is the oldest forest in the world?
14:46Approximately 180 million years old.
14:49Well, I think of the Danum Valley, which has trees that are hundreds of millions of years old.
14:56The trees are called diptocarps.
14:58They can be over 300 feet tall.
15:00They're also the home of the orangutan, which is an endangered animal that will raise its family
15:06in the upper canopies of these rainforests.
15:12WYA42wallabyway asks,
15:13Trees suck in CO2, right?
15:16So where does it go?
15:17Do they just hold their breath?
15:19Through the miracle of photosynthesis, they will absorb carbon dioxide.
15:23When it's absorbed by the tree, it makes its food.
15:27And like us, when we have too much food, we store it.
15:31A tree that is 300 years old, like a Sitka spruce in Alaska's rainforest,
15:36has been out there absorbing carbon for centuries.
15:39That carbon has been stored in its trunk and in its roots,
15:43and it's really important for cooling down the planet during the current climate crisis.
15:49At Macabre Salmon, I've always wondered why do pine forests smell of air freshener?
15:54Actually, air freshener smells like pine forest.
15:58So trees will produce a terpene when they're under stress.
16:01It's a chemical that you smell in the forest when it's at a certain level.
16:06The really interesting thing about this is that there are certain beetles that can detect those terpenes,
16:12and they will continue the process, accelerate it towards the tree's death,
16:17which is not a bad thing in the forest because as that tree dies,
16:20it's creating habitat for all this wildlife.
16:24And as it dies and falls over, it is being recycled into the nutrients in the soil.
16:30At Carter KR, I'm writing an essay on anthropogenic natural disturbances on a forest ecosystem,
16:36which is a fancy way of saying things that up trees.
16:40Well, things that really are not good for trees are clear-cut logging.
16:45When we go in there with chainsaws and we kill all the trees,
16:48that causes a major unnatural disturbance to the forest ecosystem,
16:53which causes all kinds of problems for wildlife habitat,
16:56which releases carbon to the atmosphere because the trees are no longer storing it.
17:01And it also can damage water supplies because you need to have a road system
17:06for most of these places that are doing logging.
17:08And those roads are funneling all kinds of sediment pollution into streams.
17:13And when there's a lot of trees dying in the forest, like is happening in the Rockies,
17:18that release of chemicals will trigger an outbreak of insects,
17:22like in this case the beetle outbreaks, that then kill the trees and turn the forest
17:27a kind of red coloration as the needles are dying in those forests.
17:31Trees also will experience natural mortality agents.
17:35The American chestnut is functionally extinct in the wild.
17:39There's a fungal pathogen that is very specific to American chestnut trees
17:44and kills them before they can mature and become part of the old-growth forest.
17:50At Matt Powers Soil asks, do you know the layers of a forest?
17:56Yes, I do know the layers.
17:57Let me walk you through the different layers of a tropical rainforest.
18:01So if you can imagine yourself on an elevator and you start at the top level,
18:05the penthouse, the emergent trees, then you move down a couple of floors
18:10and you're in the canopy of the forest.
18:12And that is where most of the trees are.
18:15Below the canopy, you can get into the younger trees.
18:18They're the trees that have been suppressed below the dominant canopy.
18:22Sometimes there's a tree that dies, creating a gap that will then result in a race to the top
18:28as plants try to fill that gap in, taking advantage of the nutrients and the light levels.
18:34And then we've got even more complexity on the forest floor.
18:37You kind of think of that as the basement of the forest.
18:40There's all kinds of different species and mycorrhizae fungi in some of these forests
18:45that add to a layering effect that we see in these older forests.
18:51At Mental Symphony asks,
18:53Quick question, why do trees stop growing at the same height?
18:56Me, what kind of high-ask question is that?
18:59Trees will stop growing at a certain height.
19:02Really good example in California is the coast redwoods.
19:06Those trees can get to over 300 feet tall.
19:09And they stop growing because they can't get all the nutrients and the water
19:13up to the top of the tree canopy.
19:16So they will compensate for that by living in the fog belt.
19:20And that fog belt surrounds them in moisture so that they don't have to figure out how to
19:25get all that water up to their top because they've already got water there from fog.
19:30And so the way plants get water and nutrients all the way up to their stem is they have what's
19:35called the xylem and phlolem tissue. It's like a series of tubes that allows them to get that
19:41water up all the way to their stems and out to their twigs and their branches.
19:46And it's remarkable. It's like the tree's circulatory system.
19:50Here's a question from Cora.
19:52What is the difference between a tree farm and a forest?
19:55I consider a tree farm where all the trees are planted in rows like a crop,
20:01a monoculture, a frankenforest that are grown mostly for timber yield.
20:07A forest is a living ecosystem.
20:10It's trees interacting with other vegetation, with the soils, with wildlife.
20:16The trees are different ages. They're different sizes.
20:20When you go into a frankenforest, the trees are all the same age.
20:24There's hardly any structure. There's very little habitat.
20:27So you lose all of those special benefits that we get from the natural forest.
20:34Jay SuperSwan asked, how do control burns work?
20:38Well, they're not really control burns. We like to call them prescribed fires.
20:43And so what managers of a forest might do is they might light a fire under certain conditions
20:49so that they can clear the understory in a low intensity burn and reintroduce fire to ecosystems
20:55that need frequent fire in a low intensity way.
20:59Ryder Fang Fang is asking, do trees compete with each other in nature?
21:04The trees will compete within and across species.
21:07When trees come back after like a natural disturbance, the seed rain that happens will give you a lot of
21:14tightly spaced trees that are all competing for the same limited nutrients and light levels in a forest.
21:21And they'll eventually sort it out because there are winners and losers in competition battles like this,
21:28eliminating those that are less fit and less adapted to that site.
21:33Some plants will release a chemical called an allelopath and that will kill surrounding vegetation.
21:39So that plant will prosper and outcompete its competitors.
21:44So those are all the questions for today. Thank you for watching for support.
Comments