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In this alternate scenario, five million years ago, a mass extinction hit Earth. Not a massive volcanic eruption or a devastating bolide impact, but a sudden cold snap, a transition from Miocene hothouse to Pleistocene icehouse geologically quicker than a human can say "Hi."

Half of all terrestrial species would perish in this catastrophe, and life confined to the pantropics (strictly tropical, with no other considerations of habitat) would be hit hardest. Five tropical plant species out of eight would become extinct, taking a lot of the most specialized invertebrates, amphibians, reptiles, birds and mammals with them.

The most possible result of this aftermath are plants and animals from the subtropics (like Florida, South Africa, southern China and the Mediterranean coast) migrating to and colonizing the tropics.

Now the only difference I know between tropics and subtropics is that subtropical ecosystems are seasonal (wet/dry cycles), whereas tropical ecosystems usually aren't. But is that the only difference between the two merely similar zones? Or are there other differences that I should look out for?

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  • $\begingroup$ Subtropics flood more and have less guaranteed weather. $\endgroup$ – Bellerophon Jul 11 '16 at 18:39
  • $\begingroup$ Pleistocene temperature in the tropics was only about 5 degrees lower then today. But take a look at Refugia Hypothesis for a (debated) theory on how the life in the Tropical Rainforest regions dealt with the last ice ages. $\endgroup$ – user2448131 Jul 11 '16 at 20:22
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I live in Florida and have spent plenty of time in the woods and the swamps, so I can give a few interesting weather details. I don't know if this will cause you more problems, since you asked for the difference between the two, and problematically, we don't really, actually have real rainforests here, tropical or subtropical, although we do have tropical and subtropical weather ranges in our state. You mentioned Florida specifically, so I can give you an idea of our weather in this area. I have lived in both the tropics here and subtropics.

Basic differences: South Florida: hurricanes, heat. North Florida, Central Florida: Longer dry season, will reach freezing especially in the middle of the state away from the coast.

--monoculture is present in all of Florida. While there is diversity it's not even close to what you'd find in a rainforest environ, there are also miles and miles here where you will see one type of plant, just DOMINATING--like scrub palms.

--Rainforests are rare. I think the fact that we are built on a limestone base prevents us from having the soil needed to have what you would call the strict definition of a rainforest. The conditions needed for a true rainforest are very specific. We don't have them. There are places that bank on the lack of knowledge for tourism and claim we do but, our canopy just isn't high and dense enough, among other reasons. South Florida and Central Florida does support many South American and rainforest-type critters and plants that could adapt. Many of those have found their way to North Florida. Central and North Florida will freeze, about twice a year.

--Because we don't have the kind of canopy you'd find you can see the light from above, you might actually be able to see our weird, weird weather. In a proper rainforest, everything is filtered because of the canopy. When I say weird, I mean that you can be standing in the rain, and then take a step to your left and be standing in the sun. It hails in the summer at random. It's random enough that it can hail over a house and it never makes the weather channel because it didn't hail anywhere else. The further South you get in the state, the more regular the rain gets. During the rainy season it gets unbearably hot and humid, rains by 3 or 4 pm and then clears up again. Most days, it's about 10 minutes worth of rain. It can rain all day, but that doesn't happen often on its own, unless it's a tropical storm, and we have plenty of those, and hurricanes. Waterspouts also happen if you are near the water. About once or twice a year, in Jacksonville (that's in North Florida). The clockwork rain happens more often in the tropical portion of the state, but this weather happens all over the state (even in the subtropical parts).

--Sometimes it doesn't rain. If it doesn't, things brown up pretty quickly. The further you get from the ocean, the more extreme the weather will get (with the exception of hurricanes, those don't hit there as often) but on a day to day basis, away from the coasts, it gets colder, hotter and the rains last longer and are more severe. Cold in Central Florida, away from the coastline, is a wicked bad thing. When it freezes, it feels terrible because it's humid and cold.

--In parts of South Florida, temperatures get too high to qualify for rainforest status (over 100). Ft. Lauderdale, though, actually falls into the weather & temp range of Tropical Rainforest, only none of the other conditions are really right for it.

--And I will throw in a difference that I have noticed, subtropical & tropical Florida vs. everywhere with real seasons. We are green all the time, except in the winter "dry" season, and even then we are certainly greener than the places up north. The upshot of the constant green is a lack of the vibrant green and springtime color I see up North. (Barring unnatural lawns and golf courses). It's like, up North, all the colors happen in one go, so they are brighter during spring. Flowers are brighter as well. And of course, there is no such thing as fall. The most we will get is one sensitive tree changing. Colors change slightly in Central and North Florida, but by then it's no longer tropical at that point.

--If you are looking at adaptive species of plants pushing their normal range, Florida is the place to study. Central and North Florida is an amazing mix of subtropical, tropic, and there are some environs by springs that some call "rainforests" (think there's one in the Keys as well). The canopy there is much lower, lets in more light and features less diversity. Any picture you see of a Florida "rainforest" will nearly always include sky.

--The Devil's Millhopper in Gainesville, FL is pretty close to the feel of a rainforest, as is Brick City Park in Ocala, FL. Both of these are in central Florida, both of these feature holes cut in the limestone. Within the hole is a small environment. Millhopper has an obvious spring, but Brick City Park is less so. The springs feed water constantly and the enclosed walls keep the temperatures more constant. Brick City Park has lots of Ferns, bamboo and tends to flood a lot. The weather in the area hits the subtropical range you are looking for, and in this very specific & tiny environment, could actually support tropical species, because the place offers some measure of protection from freezing (although it will freeze).

--You might also want to look at Georgia, as that's also considered subtropical, but it very, very different, mainly because of the soil and elevation in places. I have family in GA and found the weather to be more stable and less strange over all. Does freeze quite a bit more, but much of the state is considered subtropical. Here's a link to plants moving up because of weather changes.

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  • $\begingroup$ Just to clarify: $\endgroup$ – Erin Thursby Jul 20 '16 at 15:14
  • $\begingroup$ tldr: North & Central gets more of a range in daily weather, and it's pretty terrible if we don't get the rain. South Florida has clockwork rain and it's disastrous if it doesn't. South Florida has huge storm events, but otherwise has a very regular schedule for rain. North and Central doesn't have as many of the huge storm events (like hurricanes and tropical storms) but on a day to day basis gets more unpredictable weather. It will freeze at least once a year. $\endgroup$ – Erin Thursby Jul 20 '16 at 15:20
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One of the major differences between other forests and tropical rainforests is the sheer amount of biodiversity the latter can have. While upto a dozen plant species can form 90% of a temperate forest, scientists haven't even finished counting the number of plant, tree and animal groups that can be found in a tropical rainforest. Indeed, it has the largest biodiversity of any given biome, which may be why these forests have managed to survive in the form of refugia through several ice ages. Total loss of tropical rainforests would represent a very severe loss of biodiversity.

Thanks to the stable weather and temperature, the species here do not have to adapt to extreme events such as fire, drought, wind gusts or seasonal extremes. They do not need to adapt to uneven hours of sunlight such as the shorter and cold/colder winter days and very long and hot/hotter summer days. There is less climatic 'stress' on the plants and animals here. Temperate regions have stress factors that may encourage monocultures of plants/animals that have adapted to resisting these stresses. Trees/animals here have marked cycles of activity-dormancy. Some may have made clever use of the stress factors to beat competition - eg. candlenuts, eucalypts and certain pines encourage fires as a necessary component of their propagation; grasses have a short lifecycle and disperse light-weight multitudinous seeds to the winds quickly. Tropical plants have no need for these adaptations, the only 2 resources they need to compete for, and they do fiercely, are floor space and sunlight.

It rains fairly evenly throughout the year. The heat and moisture means tropical rainforests have a very quick nutrient cycle and fairly less biomass available freely - things rot away and are recycled fairly quickly. The amount of tree/plant growth possible in tropical environments given adequate sunlight is astounding. Temperate regions do not have this quick cycle. Trees here grow slower.

Tropical rainforests tend to be 'evergreen' - the trees do not all shed their leaves completely at any given time, the forest does not turn bare, as in, say a temperate forest. The very large swathes of 'green' photosynthetic area play a very important role in maintaining the climatic conditions of the area throughout the year. This further damps down marked seasonal swings to some extent.

You may be very interested in reading what this article has to say: http://www.rainforestconservation.org/rainforest-primer/2-biodiversity/d-why-is-there-so-much-biodiversity-in-tropical-rainforests/

Some resources comparing tropical and temperate rainforests: http://quest.arc.nasa.gov/projects/jason/xv/docs/TempRain.pdf http://w3.marietta.edu/~biol/biomes/temprain.htm

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  • $\begingroup$ I'm looking for differences between tropical and SUBtropical forests, not forests too far away for potential colonization in the equatorial regions. $\endgroup$ – JohnWDailey Jul 15 '16 at 13:29
  • $\begingroup$ The answer above still applies; the further you move away from the tropics the more the seasonal swings. Not too far away means a more equitable ditribution of diurnal light and warm temperatures but it still means a prolonged dry season along with tree leaflessness, fire and drought. Monsoon systems can be uneven, dumping 3-4 months of high daily precipitation dring the la nina years and failing completely during the el nino years. This climatic 'stress' does discourage biodiversity and tree growth. (worldwildlife.org/biomes/…) $\endgroup$ – artemissunshine Jul 18 '16 at 2:52
  • $\begingroup$ Where is Florida? It has a subtropical climate, right? $\endgroup$ – JohnWDailey Jul 18 '16 at 3:45
  • $\begingroup$ Florida is a subtropical/tropical wetland biome, to be specific. Comparable biomes would be the Mekong, Gangetic and other riverine delta, marked by swamps and water logging, the abundant presence of water throughout the year being the key differentiator. South-eastern Africa, southern Mexico, Indochina and central India are dry-leaf subtropical/tropical forests which do not resemble Florida by any means except perhaps during the annual rainy/flood period. $\endgroup$ – artemissunshine Jul 18 '16 at 4:12
  • $\begingroup$ Florida is both subtropical and tropical. Central & North Florida is sub, and that reaches up into Southern GA, although I would argue that the weather and amount of rainfall gets pretty different pretty fast, as does the soil. $\endgroup$ – Erin Thursby Jul 20 '16 at 6:20

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