As stated in the subject line, I'm contemplating the possibilities of a system by which land values for a given domain could change over time, specifically to model the tendency for heavily populated areas to experience degradation when subjected to the needs of a civilization for extended periods of time but also to allow for judicious management to carve out a usable realm from lands nobody else wants (subject to strict limitations on population size and whatnot).
Has anyone else experimented with similar notions? What ideas have you put into practice?
I think a challenge you might face is whether that rate of degradation would be noticable at the time scale of a campaign (presumably the adventuring lifespan of one party). I would imagine it would take at least a few generations to noticably impact the final GP value per family.
That's a feature, not a bug. The intention isn't to deplete the land within a single ruler's lifespan, but over the lifespan of a dynasty or three. If there's a model for how land degrades over generations of heavy use (and at least partially restores itself when left alone), then you've created a framework to guide every empire towards eventual decline, as dwindling resources force unsustainable choices.
Either the rulers tighten their belts and "accept" their shrinking revenues, which leads to fewer resources to weather calamities as well as rulers who lack the personal power of their forebears (thanks to reduced Domain XP), or they rage against the dying of the light and try to bolster their coffers through raised taxes, aggressive expansion, or both.
This is an interesting subject. To do it justice, though, some discussion becomes necessary regarding agricultural practices and technology as well as the impact of magic.
Regarding the last, for example, I have long assumed that a significant number of divine spells have agricultural applications that would influence productivity (e.g. cure spells for livestock, bless for soil fertility, cure disease to counter brights). Maybe this would counter soil degradation?
I was persuaded of the reality of this concept by the book "Dirt: The Erosion of Civilization", which persuasively shows how land degradation over time shifted the agricultural breadbaskets of the world to new frontiers. The demand modifiers for grain, etc. show the impact of this research.
I didn't include them in the rules for domains for a variety of reasons, but mostly because the short time horizon of typical play didn't justify the complexity.
If you haven't read "Dirt", read it; it has the answers to what you need to build this system.
I've read a great deal on this subject, but not that book. Thanks for recommendation. Soil erosion is a seriously underappreciated problem. It is quite severe throughout the US, but when do you hear anyone mention it?
I was curious as to whether or not Demand Modifiers for age took this into account (as agricultural ones go way up for long-civilized locations).
Dirt: The Erosion of Civilization is amazing. It literally changes how you view world history.
It's also vaguely terrifying, as it explains that the US Dust Bowl was actually the result of the complete collapse from erosion of the Midwest's soil, and that if we hadn't figured out industrial agriculture the area would be a wasteland by now. And it further talks about the fact that, unlike the past, there is no longer highly arable land available "in the frontier". There's nothing left.
Both of those are pretty fascinating reads, even if there's a lot of criticism of Diamond. 1491 literally changed my perception of pre-Colombian civilization, as an enormous amount of what I had previously learned is now known to be factually incorrect.
Guns, Germs, and Steel is an enjoyable book, but it offers merely one previously-unseen puzzle piece, not the be-all and end-all explanation for world-historical outcomes that some people hold it out to be.
You should throw Blood: An Epic History of Medicine and Commerce on there. It's not really relevant to ACKS, but it's a really good book. It covers the entire history of transfusions, starting with the guys who thought that pumping cow blood into crazy people would make them calm down like cows and continuing up to modern day. I'm just at the chapter where the AIDS crisis is starting!
In regards to the short time horizon of play, I was looking at this problem from a world-building perspective, and also as a means to tie land values to the age of a civilization and population density, which the Demand Modifiers already seem to do. It's one of those things with which players would never need contend or even consider, but it can drive the larger action of the millieu in fascinating directions.
It's especially intriguing to me, as I've been running games in my homebrew world for over 20 years and more than a millenium of history. Plotting the course of nations and empires over that time has always been a matter of just eyeballing it and making stuff up, but ACKS has potential to actually track this stuff and have it follow an internal logic.
1491 (and its sequel, 1493) are very much worth the read. 1491 goes into what we know about pre-Colombian American cultures, and how both those who disparage and beatify them have tended to remove agency from the people. One example is that there's some tentative evidence that the Mini Ice Age occurred because of the massive die-off of native populations that used fire to clear swathes of land for wild crops to grow in; their lowered populations and smaller burns reduced greenhouse gases by enough to exacerbate a solar minimum. The disparagers would say there weren't enough natives and they were too primitive to have any effect on Europe, while the beatifics would say the natives lived in perfect harmony with the land and wouldn't do anything to harm it. It also discusses how there were large cultures just outside of where the Europeans explored, both geographically and temporally - de Soto missed a city of 40,000 by about a hundred years and fifty miles. The next city in North America with a population of 40,000 was Philadelphia around 1800.
1493 looks at the effects of the Colombian Exchange - new food crops (the potato was responsible for the explosion in the Irish population, while potato blight was responsible for the Irish diaspora), silver (which affected Europe and Asia), and animals (the Plains tribes obviously didn't have horses until after the Spanish arrived, but they quickly became central to their lives). It's worth it just for the section on Potosi.
I didn't even know 1493 existed until a week or two ago, but it's high on my list of books to acquire and read just because of how good I thought 1491 was.
Similar to Dirt, I'm partial to "A Forest Journey: The Role of Wood in the Development of Civilization", which talks about a cycle that I vaguely recall as riverine settlement -> trade -> growth-related deforestation -> erosion -> silting (as well as loss of agricultural productivity) -> collapse of trade -> abandonment of settlement across a number of cultures and epochs.