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Thread: Positions of forests?

  1. #1
      s0meguy is offline
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    Default Positions of forests?

    Hey there. I'm new to cartography and I am trying to create a fictional world.

    I tried to make a map a few times but I am always having trouble deciding on where to put the forests on my map. I gather that they grow along one side of a mountain range, because mountain ranges trap moist air/rainclouds. Also, the soil around rivers tends to be fertile so they can also be along the rivers, but I am always having trouble deciding where exactly along the river. I also have trouble deciding what kind of vegetation there should be around the rivers otherwise. Trees or bushes or just grass? Under what other circumstances is it realistic for there to be forests?

    Thanks for your time. I would appreciate it a lot if somebody addressed these points.

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      Lukc is offline
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    It's realistic for forests to be ... where there is enough rainfall minus evaporation. You need less rainfall in colder and temperate zones than in hot and torrid zones, because there is less evaporation than when it's colder. Also, more wind = more evaporation, so that affects the spread of forests. Large herbivores affect the extent of tree cover as well, for example elephants play an important role in keeping savannas open, and possibly mammoths performed a similar role - interestingly, humans killing off large herbivores in Australia allowed eucalyptus forests to spread. Temperature affects the growth of trees, so remember the tree line (altitude) and the arctic tree line (temperature). Finally, human settlement, fires, cultivation, shifting cultivation and so forth can all affect the extent of forests. Prior to the advent of humans estimates suggest 50% of the Earth's land was covered by forests, now the percentage is about 30%. If you want to make a map realistic-looking (at least at first glance - I'm no forest biologist, so take my advice with some pinches of NaCl), do the following:

    1) determine approximate rainfall and rain shadows, and evaporation
    2) determine where secondary factors would have reduced forests (herbivores, civilizations, etc.)
    3) fill in with forests.

    Remember, green stuff tends to grow back like crazy when it's given half a chance.

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      jbgibson is offline
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    Hey, someguy - welcome to the Guild. Actually I noticed your query in the river placement thread before I noticed this - go figure :-). You're right - the issues are related. Start with everything Lukc said - it's good advice. As for fertility - sure, good soil might make the difference between semibarren scrubland and forest. But trees don't necessarily need really good soil to prosper - at least certain kinds of trees don't. My inlaws own a piece of land "not suited for anything but pine trees". You think of a rain forest as a lush, fertile zone, but I seem to recall in a bunch of the Amazon basin, much of the biomass is tied up *above* the soil surface, and the dirt may be fairly thin. I'm sure like you suspect, right along rivers is a band of great fertility.

    The Fractal Terrains world generation program uses a simplified model for climate zones / land cover. It has to, if it's to run on a generic PC's processing power. But its base assumptions are probably sound - lots and lots of area would be covered by forest of some sort, absent modifying effects like human habitation. I usually have to manually tweak the default FT wetness downward in areas before I can get any extensive grasslands or savannah. To Lukc's "50% down to 30% forest cover", add the anecdotal statement that when Europeans came to the New World a squirrel could probably run from the Atlantic to the Mississippi without touching the ground :-). That makes an important input just what is the density of human habitation in your lands, and what are their activities? Active farmers can denude an area of forests in a few generations. Further, (over) active grazing can turn grasslands into desert in a few more generations. Acute dry seasons can amplify forests' tendency to go up in flames over vast swaths. But contrariwise, some kinds of forest actually NEED periodic fires to prosper <shrug>.

    You're right - if prevailing winds blow across mountain ranges just one way, the upwind side is ripe for rain forests and jungles. Downwind could be thinner trees, or scrublands, or savannah, or pure grasslands. Or of course, desert.

    Tell us more about the topography you have (or want to have), and the human (or other intelligent creature :-) ) part of your equation. Same piece of originally-forested land with a million dwarves might look deserted (if they're underground), with a million elves might be a lush garden of varying canopy, and with a million humans could be one great bare farmland. Your call. Non-humanoid occupants too - a million elephants forced into said forest from elsewhere might trample, eat, and otherwise strip a forest. A million-million pine borer beetles or gypsy moths could strip a lush forest back to stumps and grasses too, or could cause a shift to less-typical but resistant trees.

    Or like Lukc implies - subtract 990,000 of those humans by epidemic, and you could have jungle reclaiming a once-great civilization in fifty to eighty years. With kudzu, the re-blanketing of farmland could be much sooner. Me, I've speculated in storylines about the use of kudzu as a biological weapon :-).

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      Veldehar is offline
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    Another interesting note with human infestation is that we tend to destroy trees and spread trees, as they are so useful. In open plains human settlement will tend to bring trees with it, if adequately advanced to do so, to use for wind breaks and other things. Hardy fast growing non-indigenous trees can spread to aid in the destruction of natural prairie. Cutting little cedar trees is often necessary to preserve natural prairie, as an example. A tree can become a weed... and spread that elven empire, heh heh.

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      s0meguy is offline
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    Thanks a lot for all the elaborate answers. I'll take everything here in consideration when designing my world map, and then regional maps.

    The world is the first in a universe that I'm designing - the world from where humans originate. It is supposed to be a huge garden world (a super-earth) with different sentient species that split off from the human evolutionary line that spread across different continents that are isolated for a long time until advanced shipbuilding is invented. I would design the world and its inhabitants in various stages, starting with when its sentients inhabitants are still relatively primitive and sparsely populated, but advanced enough to create a wide array of civilizations that are diverse in itself - think 3000-6000 years ago on Earth. The world should be green in general, but I would like all different types of landscape to have a place; barren desert to deciduous and evergreen forests, rainforests, jungle, tundra and savannah and grasslands, marshes, ice, everything. I would like to design the world in different stages, until they become spacefaring and start colonizing other worlds.

    It's a world, ultimately universe, building exercise for it's own sake for now, and also to set stories in. It's proving a lot more complicated than I thought. Ecosystems are complicated things. I have been delving into wikipedia for a few weeks now and reading at the local library. It's overwhelming to think of all the theory involved in creating a realistic, diverse landscape.

    The most advanced world making utility that I have found, Fractal Terrains, creates unconvincing worlds to me. They are too monotone in climate (rainfall is the same just about everywhere, except extremely high altitude, and temperatures are also not varied enough for me by far), and the shapes of the continents don't make sense compared to those on Earth that sort of fit together like a jigsaw puzzle. It also does not seem to take into account that some parts of the planet receive a lot more starlight and how the atmosphere and ocean currents influence climates. Those are just a few of the major considerations. Also, all landmasses always rise above the sea for hundreds of meters right at the coast and have a tendency to rise to thousands of meters shortly. I don't want that. A lot of the lands should be relatively close to the sea altitude-wise.

    So I will have to use my truly most advanced available utility to design my worlds: my brains, and design my world by hand in Photoshop. I am glad to have found this place though. There are some awesome photoshop tutorials here, and there seem to be a lot of great, passionate people that don't mind helping out.

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      Veldehar is offline
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    And Fractal Terrains is a bit crude when creating a world from scratch, which is annoying. The amount of knowledge that would go into creating a truly realistic world would be staggering. Even taking Earth and altering it a bit, say making the Sahara green rather than desert would have affects that we simply do not know about. It would affect tropical storms/hurricanes on the east coast of the US, potentially diminish them, but what else might it do? Would southern Europe grow cooler? for instance.

    In the case of the world I am creating, there is way more land at and near the equator than Earth... how would this affect the evaporation and moisture carried by the ITCZ? Could it have massive effect on the climate of the world? You bet. Greater % of land overall and much more in the southern hemisphere? all things that would mess with untold things. I have finally put in enough study to be able to make guesses that will undoubtedly be incorrect, and yet, they should more less be a potential reality or at least close enough to make it real to casual observation.

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      s0meguy is offline
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    Quote Originally Posted by Veldehar View Post
    And Fractal Terrains is a bit crude when creating a world from scratch, which is annoying. The amount of knowledge that would go into creating a truly realistic world would be staggering. Even taking Earth and altering it a bit, say making the Sahara green rather than desert would have affects that we simply do not know about. It would affect tropical storms/hurricanes on the east coast of the US, potentially diminish them, but what else might it do? Would southern Europe grow cooler? for instance.

    In the case of the world I am creating, there is way more land at and near the equator than Earth... how would this affect the evaporation and moisture carried by the ITCZ? Could it have massive effect on the climate of the world? You bet. Greater % of land overall and much more in the southern hemisphere? all things that would mess with untold things. I have finally put in enough study to be able to make guesses that will undoubtedly be incorrect, and yet, they should more less be a potential reality or at least close enough to make it real to casual observation.
    So did you end up using FT to make your world map anyway, or are you using photoshop?

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      Veldehar is offline
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    I am doing both... I used FT to jot out the basic landforms without a concern for mountains etc, and then I am taking those shapes into PS, filling in details etc. This gives me a quick way to bring that map back in as an overlay in FT for (hopefully) easy transitions from the various map projections, primarily for orthographic views, and to allow easier measurement of distance at various places on the globe. Both FT and CC3 will serve some practical purposes, but all terrain and climate will come from grunt labor, heh heh.

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