Forest Preserve question

[agentsmith952]

I have my super forest preserve city going with a national park located in the city. In my fat cross, there is a river that separate the three southern most tiles from the rest of the fat cross.

I've had forest preserves in most of my fat cross for some time and the forests have spread all throughout there, but I have yet to have a forest spread across the river. Can forest preserves spread forests across rivers?

 

[ori]

Can forest preserves spread forests across rivers?

forest preserves increase the probability of forest spreading to the tiles N, E, W, S of the forest preserve tile, rivers do not play any role, roads/railroads on the nonforest tile decrease the likelyhood of forest growth.

 

[agentsmith952]

forest preserves increase the probability of forest spreading to the tiles N, E, W, S of the forest preserve tile, rivers do not play any role, roads/railroads on the nonforest tile decrease the likelyhood of forest growth.

Maybe I'll check for rails, but my reserves have been there a LONG time, and the whole fat cross is covered except for across the river...

 

[Stylesrj]

I have a problem with preserves and all that. I try and spread it but to no avail. I have Tundra tiles and preserves next to them. I want to be able to plant forests, like in Civ III

How do you pillage your own railroads, short of nuking them? My troops can't do it for some reason

 

[ori]

Maybe I'll check for rails, but my reserves have been there a LONG time, and the whole fat cross is covered except for across the river...

The thing is that the chance is small to begin with so it is well possible that it will not spread to a particular tile. Also it only works in the cardinal directions...

How do you pillage your own railroads, short of nuking them? My troops can't do it for some reason

Have Barbs do it seriously there is no way - you can pillage your own improvements but not roads/railroads

 

[lulu135]

To quantify:
There is a base chance of 0.1% for forest to spread, per square, per turn. This is cumulative based on the number of adjacent forests, so a square in the middle of a 4 forest cross has a 0.4% chance. If there is a preserve in one direction, the chance increases to 0.8% per square per turn. (or 3.2% if in the middle of a 4 preserve cross) This means, assuming only one adjacent forest with preserve, it will still take on average over 100 turns for the forest to spread to any given square.

Finally, all these probabilities are cut in half if there is a road.

 

[Lord_Zath]

so the moral of the story is don't try to spread forests?

 

[lulu135]

so the moral of the story is don't try to spread forests?

I wouldn't say that. The probabilities I quoted are per-square, per-turn. So if you have a lot of eligible squares the probability of at least some of them growing forests over a few dozen turns is pretty good. The moral I draw is that when you are chopping for , it's best to chop in a checkerboard pattern to maximize the chance of regrowth.

 

[agentsmith952]

Found my problem. It seems I was confused as to which side of the river my watermills were on. Turns out they were on the tiles I wanted to spread forests and not on the other side of the river for my neighboring cities.

Don't I feel like a horse's patoot...

 

[Infantry#14]

it would be great if one can plant forest. Maybe after biology, you can plant seeds on a given tile. After 10 turns, it will grow into a forest, but it wont give you hammers if you chop it.

 

[KrikkitTwo]

To quantify:
There is a base chance of 0.1% for forest to spread, per square, per turn. This is cumulative based on the number of adjacent forests, so a square in the middle of a 4 forest cross has a 0.4% chance. If there is a preserve in one direction, the chance increases to 0.8% per square per turn. (or 3.2% if in the middle of a 4 preserve cross) This means, assuming only one adjacent forest with preserve, it will still take on average over 100 turns for the forest to spread to any given square.

Finally, all these probabilities are cut in half if there is a road.

actually its less than that

Forest spread is 8/10000 =0.08% (up to 0.32%)
With a Preserve it is 64/10000=0.64% (up to 2.56%)

The road affects the odds by subracting 8/10000 from the tile it spreads from
AND it can't spread onto a tile with an improvement.

 

[lulu135]

actually its less than that

Forest spread is 8/10000 =0.08% (up to 0.32%)
With a Preserve it is 64/10000=0.64% (up to 2.56%)

The road affects the odds by subracting 8/10000 from the tile it spreads from
AND it can't spread onto a tile with an improvement.

Yes those are the numbers in the XML/Terrain/ but there is also a +25% global modifier that I baked into my numbers which brings it up to 0.4% and 3.2% respectively. And the road penalty is calculated on the destination square not the source square and it does not subtract from the probability it is applied as a separate multiplication.

Source: CvPlot.cpp line 8087

 

[Peng Qi]

AND it can't spread onto a tile with an improvement.

Can it spread into a tile with a camp on it? If not, that's kind of goofy if you ask me.

 

[Stylesrj]

I can't use Barbarians to pillage my railroads. I'm one of those types who actually build a freaking great wall! Besides, by the time I have forest preserves, there are no more Barbs as there is no more land for them to appear on.
Short of nuking the square with a tactical nuke, I can't get rid of that one railroad!

 

[ori]

Can it spread into a tile with a camp on it? If not, that's kind of goofy if you ask me.

It can spread onto any tile with an improvement that allows forest, i.e. camp, fort, lumbermill, forest preserve (yes I know that you cannot build the latter two without forest, but you can worldbuild those ).

 

[thomson_2001]

im a bit slow...only JUST realised forest preserves give you smiles in nearby cities....thought id post in case anyone else had missed this

 

[lulu135]

It can spread onto any tile with an improvement that allows forest, i.e. camp, fort, lumbermill, forest preserve (yes I know that you cannot build the latter two without forest, but you can worldbuild those ).

I don't think that's the case. There's a line "if (getImprovementType() == NO_IMPROVEMENT)" around the forest spreading code which indicates that it won't spread if there is any improvement at all.

im a bit slow...only JUST realised forest preserves give you smiles in nearby cities....thought id post in case anyone else had missed this

If you switch to environmentalism it also gives you

 

[ori]

I don't think that's the case. There's a line "if (getImprovementType() == NO_IMPROVEMENT)" around the forest spreading code which indicates that it won't spread if there is any improvement at all.

you are right - for some reason I had this code differently in my memory - but I looked at it a couple months ago so I remembered incorrectly

 

[Psyringe]

Hmm, in my last game Boudica had a camp on a tile that also had jungle on it. If building a camp removes the jungle, and jungle can't spread to tiles with improvements, how then could this happen?

 

[agentsmith952]

Hmm, in my last game Boudica had a camp on a tile that also had jungle on it. If building a camp removes the jungle, and jungle can't spread to tiles with improvements, how then could this happen?

If there is a forest/jungle tile on a resource that you can build a camp on, then building the camp will not remove the forest. This is a good strategy with forests to get extra hammers from a camp tile. However, if there is no forest or it is removed before the camp is built, forests will never spread there since there is now an improvement on the tile.

So, if you can wiat to build a camp improvement, try and let a forest spread there before you build the camp to make the improvement more productive.