Dragonriders of Pern/Headscratchers: Difference between revisions

*** Sooner or later? Dragons have only ''existed'' for a few thousand years! There hasn't been ''time'' for their suicides to take away any significant amount of Pern's biomass.

** In Dragondrums, Piemur notices that huge schools of fish come to surface after Threadfall to eat drowned Thread. I wouldn't be surprised if the ashes from burning it made really good ''plant'' food, so it probably ''does'' makes up really well for the dragons going ''between'' to die.

*** It's not about planetary mass, it's about ''biomass''. Which is much, much smaller, see below. Even further than that, if the biology is anything like Earth's, the major limiting factor would be fixed (plant-available) nitrogen. I don't know how much of this there is, but it's small enough on Earth that our planet could not support our current population if someone hadn't [http://www.radiolab.org/2012/jan/09/how-do-you-solve-problem-fritz-haber/ invented a process] to chemically fix nitrogen sometime in the past 100 years. But as someone said above, no doubt drowned Thread and Thread ash return nitrogen & other elements of fertility to the soil and seas.

** On the other hand, as Mike pointed out in "The Moon Is A Harsh Mistress", there is a world of difference (pun intended) between the mass of a planet and the portion of that mass that is involved in the life cycle. It's not just the dragons themselves - according to the Dragonlover's Guide, they also excrete wastes between, and 3000 dragons at a time for 2500 years adds up to a big pile of...well, you know what I mean.