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Presume a decade of darkness, after a several months of steadily shortening daylight. Assume that the temperature and weather patterns remain (inexplicably) fairly unchanged.

Ten years later, when the sun comes back: which species of flora and fauna are most likely to be capable of recovering? I know that some plants produce seeds that can sprout after extended period of dormancy, but not which species have seeds for which a decade of unsuitable environment is nothing, and which are likely to die out after a few years of not being able to reproduce/grow. Categories are useful, it doesn't need to be specifics; e.g., pitted fruits or pines or root veggies, or whatever. The internet just wants to tell me how long I can store my seed packets for, and I want to know which types of seeds can actually pull off long-term storage in the wild.

If you've got any idea which plants' survival chances might also suffer more/less from the depradations of desperate starving animals, that would also be helpful, but isn't as critical.

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  • $\begingroup$ Excellently written question on a real world topic. Welcome to the site. $\endgroup$ – James Jul 18 '18 at 15:51
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    $\begingroup$ I know you said the same temperature but if the temperature plummeted and the Earth froze, a lot of the plants might recover once thawed. $\endgroup$ – Tracy Cramer Jul 18 '18 at 17:11
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    $\begingroup$ In the question body you ask about flora and fauna (but mostly focus on flora), in the question title, you only ask about flora. Wouldn't the title fit the question body better if it were changed from "which plant species" to "which species"? (it confused me a bit so my answer only dealt with plants) $\endgroup$ – user42528 Jul 19 '18 at 20:51

11 Answers 11

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which species of flora and fauna are most likely to be capable of recovering?

Though some seeds can still be vital after more than 10 years (see Pink Sweetener's answer), animal's seeds won't generally last that long. Except maybe some tardigrade and bacteria, you will not have much more animal life around.

And that brings a huge problem: you will have some plants sprouting, but then, with no insects or other animals around to do their duties as pollen vectors, only anemophile plants will be able to reproduce (i.e. conifers). You might also have local communities of plants reproducing though root propagation, but that is necessarily limited as form of propagation.

To summarize, you will end up with a rather less diverse word, with many less species, where evolution has to start over again. Cave organisms or the habitats existing around volcanic vents would probably be unaffected, but they represent a small fraction of the entire biome, anyway, and have no known role in plant reproduction.

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  • $\begingroup$ You should add the animals that are adapted to live in a cavern, like the Proteus anguinus, and the extremophiles which are not just bacteria, but it is true that are a very limited number (seen as species number) $\endgroup$ – Gianluca Jul 18 '18 at 6:12
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    $\begingroup$ not really all of them. For example, the Proteus I cited can survive eating his own larvae and little crustaceans (in very little quantity) and it is showed in experiments that can live 10/12 years without eating, They already live like that, so to them nothing change. $\endgroup$ – Gianluca Jul 18 '18 at 8:26
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    $\begingroup$ Some cave animals can now thrive all around the wolrd and fungus will feast for a decade over all that orgnic matter. Of course marine life will be disrupted etc. After a decade all that fungus and the new darkness ecossystem will start to fall apart and again lots of organic matter ling around etc. The only thing I cannot see on the answers is hoe marine life will comeback without fitoplancton $\endgroup$ – jean Jul 18 '18 at 11:31
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    $\begingroup$ I'm not totally convinced all animals would be dead. Flies might survive on rot, some cicada's probably would be fine by being dormant, some scavenger and cannibal species might be able to spiral down for 10 years. $\endgroup$ – user25818 Jul 18 '18 at 16:07
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    $\begingroup$ @notstoreboughtdirt Cicadas would be dead. They don't go totally dormant, but rather bury themselves underground as larvae, where they munch on tree roots. No tree roots, no more cicadas. All animals rely on plants to survive. Unless there is some stimuli to put them in a 10 year dormant state, all dead. As L.Dutch notes, that includes water bears and a few other tiny critters. Some vernal pond animals, like trilobites, might survive. Can't think of much else. $\endgroup$ – Pink Sweetener Jul 19 '18 at 14:09
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Many plants produce seeds which would remain viable after 10 years. A few years ago, a group of students managed to produce a crop from 800 year old squash seeds.

Online, you will find charts indicating that many common garden vegetable seeds are only good for 2-5 years. This is more an indication of "best-by" dates: the majority of a sample of seeds might become spoiled after 10 years, but even delicate nightshades like tomatoes will have a few viable seeds after a decade.

In fact, from personal experience and a bit of online research, a better question might be which plant seeds would not be viable after 10 years. Many would make it! Plants are hardy things.

That said, a ten year blackout would have a devastating ecological effect that would drive many species to extinction, without doubt, but it's hard to count off all of the species that would die because of this. On the one hand you might think plants earlier in ecological succession, better adapted to disruption, might survive better - but on the other hand perhaps later succession plants are better adapted to long dormancy period. There are a lot of hard factors to consider.

Sorry I can't give a clearer answer. Hope someone smarter than me chips in!

EDIT: Just another note. One of the biggest ecological problems would probably be atmospheric. The obvious issue here is no oxygen without plants. When the sun returns, you still wouldn't see plants return because plants need oxygen just as much as animals do. But even if the oxygen supply were somehow sci-fied away, there is also the issue of CO2: after the sun blacks out, virtually all plants on earth will die, and their decaying remains would release vast quantities of carbon dioxide and methane. Runaway greenhouse gas effect, ocean acidification, and probably even asphyxiation (even with oxygen somehow supplied!) follows.

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  • $\begingroup$ I'd take the negative version of the answer too! I'm trying to have an at least slightly ecologically accurate guess at the resulting loss in biodiversity, for which this was my first stab at a question. $\endgroup$ – Hufflehobbit Jul 18 '18 at 3:21
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    $\begingroup$ Interesting about the surrounding ecology. I doubt social insects like bees would make it, which means a lot of flowering plants would suddenly have very few/no pollinators. $\endgroup$ – Ynneadwraith Jul 18 '18 at 9:13
  • $\begingroup$ @Ynneadwraith Very good point. I was tired and completely forgot that animals exist. This sounds like a snarky response to your comment, but I'm being totally sincere. $\endgroup$ – Pink Sweetener Jul 18 '18 at 15:01
  • $\begingroup$ @PinkSweetener Haha no worries ;) didn't get any snark from that. $\endgroup$ – Ynneadwraith Jul 18 '18 at 15:10
  • $\begingroup$ @Hufflehobbit Y.Dutch has a spot-on answer, but I added a little extra info above. $\endgroup$ – Pink Sweetener Jul 18 '18 at 18:35
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In an uncontrolled environment, I'm sure purslane would survive, as well as a number of other noxious weeds. The seeds can be dormant in soil for something like 40+ years. Purslane is edible, however.

Field bindweed seeds can stay viable for 50 years. It's a perennial with rhizomes (so when it sprouts, it won't have to rely on seeds to be around for a really long time).

Lambsquarter and mallow seeds can remain viable in soil for decades.

There are many plants that could survive. You might look at lists of noxious weeds, such as these, to study for those that would suit your purposes.

In a controlled environment, you can store many kinds of vegetable seeds for 10+ years and still grow them afterward (although stores only guarantee them for a shorter period, and germination rates may or may not change), including tomatoes (which don't require insects for pollination per se, since they have perfect flowers with both male and female parts, and wind can cause them to pollinate themselves).

I'd guess life that uses chemosynthesis, including some life in the deepest parts of the ocean, would survive, and potentially go higher in the ocean.

My guess is that a hitherto uncommon set of life-forms would prosper in the dark, and eventually colonize the planet. Given a period of eons, you might get some really interesting things going on, but after just ten years, it's hard to say. You'd still have life, whatever the case, including weeds. Much of the life that would survive afterward would probably be able to reproduce without pollinating insects, whether or not it could also reproduce with their help.

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In terms of the types of plants which will survive best, annuals and biennials have the most resistant seeds, while nuts and larger seeds do not last as long (according to iowa state university http://agron-www.agron.iastate.edu/~weeds/Ag317/bioeco/lifecycle/seedbank.html).

They also note that the depth at which seeds are buried affects their survival - with seeds deeper in the soil lasting longer. Thus plowing the soil could turn up seeds which have not survived as well at the soil surface.

Grass seeds apparently do not survive as well, according to J Lewis (1973).(LEWIS, J. (1973), LONGEVITY OF CROP AND WEED SEEDS: SURVIVAL AFTER 20 YEARS IN SOIL. Weed Research, 13: 179-191. doi:10.1111/j.1365-3180.1973.tb01262.x). I tried to find out if grasses could persist as rhizomes, but I didn't find much data on that.

With regards to the problem of your research only turning up shelf-lives of seed packets, I would recommend researching "the soil seed bank", as it should turn up more results about the survival of seeds in the soil.

Persistence in the soil seed bank refers to how long seeds last in the soil in normal conditions, it takes into account those seeds which germinate. The germination process has a degree of randomness, so while some seeds germinate every year, some remain. Seeds may also be deeply buried, where conditions inhibit germination, and only released later by human actions or natural events.

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https://en.wikipedia.org/wiki/Lantana (in particular, the roots left in soil) is so robust it's almost ineradicable. I've seen it spring back up approx. ten years after being covered by concrete.

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It might not be answering the question, by not suggesting any plants, but if the temperature and weather are staying the same, seeds won't last until there is sunlight.

The first thing that sprang to my mind when reading your question is that most plants in the soil use the seasonal temperature changes and moisture levels to trigger when to start growing/germinate.

They don't know that there is sufficient sunlight above ground (but it is the usual reason for the temperature rise), and expend most of their stored energy growing to the surface. Without sunlight for ten years, I'd expect most of the plants in the ground to surface in spring only to die from lack of sunlight.

Most of the other answers focus on the viability of seeds - but none mention if/how those seeds would not germinate before the arrival of sunlight. If you've got humans (or other) storing the seeds and planting when the sunlight returns, that'd work - but I'm not sure there are any plants that would re-populate without external intervention.

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  • $\begingroup$ This kind of larger ecological observation is tremendously helpful, as someone who kills every plant I try to grow. What naturally-occuring situations might cause seeds/roots/etc to not germinate and promptly die? Being buried deeply? Getting stuck in some poor dead squirrel's den? $\endgroup$ – Hufflehobbit Jul 19 '18 at 14:41
  • $\begingroup$ @Hufflehobbit Most seeds/root/etc will die if exposed to something like too much heat, acid, etc or being drowned in too water water for too long. Being buried too deeply isn't a killer in itself IIUC, unless it is crushed under the weight - and may aid survival (eg avoiding ground frost that only penetrates so deep). Getting stuck in a den may in fact be beneficial - if dry and temperature stable the seed will lay dormant and not attempt to grow. $\endgroup$ – Grhm Jul 19 '18 at 14:51
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Other answers have pointed out that even if seeds can stay technically viable, that doesn't mean they'd survive in the described environment; for example, environmental factors could trigger their germination before the 10 years are out which would kill them.

I'll point out in turn that this is true, but you need to consider the amount of seeds and species involved here. It might seem implausible to hypothesize a seed that happened to be buried too deep to be affected by environmental factors, and then happened to get brought back to the surface by some disturbance or erosion right after the sunlight came back. But they key is, there are trillions of seeds on Earth at any given time. And any seed that does germinate after the decade of darkness will find itself in a world with no competition for light and resources, and abundant nutrients in the soil (because the last other living things in the darkness will have been the decomposers feasting on all the dead matter). Those plants are likely to thrive on an individual level, and some will even be able to reproduce, and once that happens there will be nothing preventing them from spreading as far as the environment, and evolution on the longer term, will let them.

This even affects the question of viability, frankly. A plant for whom 99% of seeds are nonviable after 10 years would qualify "not having viable seeds after 10 years" by most standards, but if the plant is common enough then 99% nonviable still leaves quite a few seeds with a chance to make it in the new world.

(one could counter this point however by pointing out that plants with seeds that are likely to make it through ten years of darkness will be much more numerous, which is relevant to the question of what the overall flora will look like. It is also true however that once X plants have grown back and managed to reproduce, "survival of seeds for 10 years of darkness" is no longer the only factor in how common they'd be another 10 years down the line. At that point being successful in the new environment will be more important.)

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Best chance of survival would be:

Flora: mushrooms

Fauna: ocean floor dwellers

These guys don't require sunlight already, so, in the absence of any other changes they should happily continue during the big dark.

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  • $\begingroup$ Problem is that mushrooms need food provided by green plants (either as symbionts or living from dead plants). Without the reappearance of green plants the mushrooms and fungi are dead sooner or later $\endgroup$ – jknappen Jul 20 '18 at 16:22
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Other answers have established that there are plant seeds that would be viable after 10 years, however, I'm not sure that's entirely relevant.

Consider that if the temperature and everything else stay the same, viable seeds are going to sprout; Seeds can't tell if there's light or not when underground. Given this, most of the viable seeds are going to sprout into a world with no light, then die. Similarly, any perennials are going to grow again in the spring, exhaust their energy reserves, make none of them back, then die.

I imagine 10 years of this will exhaust a vast majority of the viable seeds in the world unless they are specifically preserved by humans or similar until the light comes back.

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    $\begingroup$ Hello, xyfjm nml.j, and welcome to Worldbuilding.SE! Please take our tour and visit the help center to learn more about the way the site works. Have a nice day! $\endgroup$ – Gryphon Jul 19 '18 at 13:04
  • $\begingroup$ Thanks for this answer xyfjm, its prompted me to improve my answer about the soil seed bank, by adding a paragraph on the issue of early germination. $\endgroup$ – user42528 Jul 19 '18 at 20:43
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Bulbs

A common type of house plant are ornamental bulbs which have large energy stores below the surface for their dormancy. Most of the bulb styled plants can reproduce asexually, by creating new bulbs off of the largest one which can be broken off and planted else where.

These kinds of plants would love this new environment and survive the decades of darkness to get there.

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It depends on your technological advancement and/or do they have to survive on there own in the wild.

If you have the technology you can completely nullify the problem. Why be stuck with old seeds when you can have fresh one!

LED lighting to the rescue, using shades of red and blue light you can grow plants. I was just watching a science show where they were growing lettuce or was it cabbage in half the time with LED lighting. They had no soil, but a white Styrofoam like sheets. They pumped in water with nutrients in the water, and grew them just fine. They found 20% of the time darkness was needed for that particular crop.

You can do it indoors with no external light source.

Keep growing, and maintain a fresh stock of seeds.

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