Change the way we calculate survival.  Before, age and environment determined health and probability of survival each year was based on health.  That meant that in unhealthy conditions, long lived plants were affected much more than short lived plants.  As conditions worsened, average age oflong-lived plants dropped rapidly until it was the same as medium lived plants.  Then long and medium plants age dropped rapidly until it matched short lived plants.  Then all plants age dropped together. So instead of health directly affecting survival probability in each year, only age affects it directly, but health reduces the maximum lifespan so it has an indirect affect on survival.  This makes changing the environment have an affect on average age that is proportional to species lifespan (reducing health by 50% reduces the average age of all species by about 50%).
Change the way we calculate survival.  Before, age and environment
determined health and probability of survival each year was based on
health.  That meant that in unhealthy conditions, long lived plants
were affected much more than short lived plants.  As conditions worsened,
average age oflong-lived plants dropped rapidly until it was the same
as medium lived plants.  Then long and medium plants age dropped rapidly
until it matched short lived plants.  Then all plants age dropped together.
So instead of health directly affecting survival probability in each year,
only age affects it directly, but health reduces the maximum lifespan so it
has an indirect affect on survival.  This makes changing the environment have
an affect on average age that is proportional to species lifespan (reducing
health by 50% reduces the average age of all species by about 50%).

aduffy70/VPCsim-Unity