# Burned earth... regrowth time? **URL:** \ **Category:** Factual Questions\ **Created:** [August 3, 2002, 11:20am UTC](https://boards.straightdope.com/t/burned-earth-regrowth-time/122162 "2002-08-03T11:20:02Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![Tristan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tristan/32/18058_2.png) [@Tristan](https://boards.straightdope.com/u/Tristan)\ **Post date:** [August 3, 2002, 11:20am UTC](https://boards.straightdope.com/t/burned-earth-regrowth-time/122162/1 "2002-08-03T11:20:02Z")
Alright folks, I have an odd one, inspired that awful crapfest, “Reign of Fire”. Saying something like that happened, and most large plant life and a great majority of land based life was burned/destroyed. How long would it take, after the dragons went away or what have you, to regrow? I imagine within one year we would see grasses and wild grains, but how long for decent sized trees? How badly skewed would the ecosystem be? Would we live? ---
**Author:** ![Fern\_Forest](https://avatars.discourse-cdn.com/v4/letter/f/71c47a/32.png) [@Fern\_Forest](https://boards.straightdope.com/u/Fern_Forest)\ **Post date:** [August 3, 2002, 11:35am UTC](https://boards.straightdope.com/t/burned-earth-regrowth-time/122162/2 "2002-08-03T11:35:36Z")
It depends on how hotly the fire burned (Dragon fire is supposed to be incredibly hot) and whether or not the area experienced strong rainfall shortly after. A lot of rain after a powerful fire can wash away all the topsoil and the important minerals necessary for plant life. I saw a bit on the news recently about a super hot fire that burned over Flagstaff Arizona almost 30 years ago. And was followed by, I believe floods. Only a few small plants grow there and they said it could take 1000s of years before it returns to the way it was. I’ll see if I can find a link. Since that movie was set in England I would say they’re in for some bad times. ---
**Author:** ![Fern\_Forest](https://avatars.discourse-cdn.com/v4/letter/f/71c47a/32.png) [@Fern\_Forest](https://boards.straightdope.com/u/Fern_Forest)\ **Post date:** [August 3, 2002, 11:57am UTC](https://boards.straightdope.com/t/burned-earth-regrowth-time/122162/3 "2002-08-03T11:57:38Z")
[NAU Cline Image Library](http://www.nau.edu/library/speccoll/imagedb.html) Search for Radio Fire. There’s an image from 2001 showing the damage after 24 years. [NAU Alumnai Association Newsletter](http://www.naualumni.com/News/News.cfm?ID=910&c=4) > [@](#): > > Researchers say the ponderosa pine forest that once covered Mount Elden won’t be growing back any time soon because the shallow, thin soils that existed on top of the bedrock took thousands of years to develop and will take that long to come back. Now England has a lot of thick rich soil so they would probably be better off, it depends again on how widespread the fire was. Now Scotland would be in for a lot of trouble. ---
**Author:** ![Muffin](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/muffin/32/4341_2.png) [@Muffin](https://boards.straightdope.com/u/Muffin)\ **Post date:** [August 3, 2002, 3:54pm UTC](https://boards.straightdope.com/t/burned-earth-regrowth-time/122162/4 "2002-08-03T15:54:23Z")
A lot would depend on what happened to the soil. For example, in the Sudbury area at the turn of the century, sulpher dioxide fumes and resulting sulphuric acid rain from open pit roasting killed all the vegetation in many areas of the region (especially Coniston and Murray Mine). With no live roots, the soil erroded away, leaving bedrock. Lichen is about all that grows on bedrock, thus a moonscape remained even after the open pit roasting was stopped. Catch areas where duff could accumulate regenerated on their own, but exposed areas simply did not regenerate at all, leaving dead zones. Regeneration only occurred when sandbags filled with lime were placed on the bedrock, providing something in which seeds could grow roots, and also stabilizing the acidic runoff. ---
**Author:** ![Finagle](https://avatars.discourse-cdn.com/v4/letter/f/b19c9b/32.png) [@Finagle](https://boards.straightdope.com/u/Finagle)\ **Post date:** [August 3, 2002, 4:33pm UTC](https://boards.straightdope.com/t/burned-earth-regrowth-time/122162/5 "2002-08-03T16:33:27Z")
Mt. St. Helens. I first visited it six years or so after the eruption. Pretty much still a moonscape with, as you said, grasses and some wildflowers but _no_ trees. Ten year later, visited it again. It was coming back reasonably well, with lots of small tree growth. So, at a guess, if you have a reasonable soil base, in 15-30 years you will have young forest. In 100 years, you won’t be able to tell. Another anecdote – New England was pretty much deforested 100 years ago due to farming and firewood production. Then they found better farm land out West and all the marginal farmers left. People started cooking and heating with coal and gas. New England is now \* heavily \* forested, once you get away from the strip malls and housing developments. It’s not old growth forest, but there’s a lot of it. ---
**Author:** ![ftg](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ftg/32/2801_2.png) [@ftg](https://boards.straightdope.com/u/ftg)\ **Post date:** [August 3, 2002, 4:51pm UTC](https://boards.straightdope.com/t/burned-earth-regrowth-time/122162/6 "2002-08-03T16:51:27Z")
Leaving aside industrial damage and volcanoes (ash is actually a fertile soil) and sticking to just fire: A really harsh fire can form a nasty crust in the uppermost soil. A mild fire won’t. Standard nearly yearly burnings are mild enough that reqrowth happens quickly. But if a lot of vegation is built up, you can a hot enough fire to leave a crust. And that crust takes many years to break down. In addition, the crust screws up water percolation so flood issues are more serious. This is a problem in areas such as S. Cal. where fires are infrequent and therefore nasty. The next big rain causes a big mudslide problems. Periodic burnings would eliminate a lot of these problems. Oh, well. So: how much vegetation and how hot is the fire? ---
**Author:** ![Bryan\_Ekers](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bryan_ekers/32/183_2.png) [@Bryan\_Ekers](https://boards.straightdope.com/u/Bryan_Ekers)\ **Post date:** [August 3, 2002, 6:40pm UTC](https://boards.straightdope.com/t/burned-earth-regrowth-time/122162/7 "2002-08-03T18:40:01Z")
> [@](#): > > \*Originally posted by Osiris \* > I saw a bit on the news recently about a super hot fire that burned over Flagstaff Arizona almost 30 years ago. And was followed by, I believe floods. Sounds like my last vacation. [sub]Lousy travel agent…[/sub] ---
**Author:** ![Muffin](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/muffin/32/4341_2.png) [@Muffin](https://boards.straightdope.com/u/Muffin)\ **Post date:** [August 3, 2002, 7:44pm UTC](https://boards.straightdope.com/t/burned-earth-regrowth-time/122162/8 "2002-08-03T19:44:12Z")
It also depends on the type of forest which was burned, for some rely on fires. For example, Canada’s boreal forests need fire to add nutrients to the soil, to burn off shade causing scrub, and to help open cones. Want a healthy forest up here? Then once in a while it’s burn baby burn.