Good points. I guess the arrival of a large population of seasonally migratory birds, or the day the figs simultaneously ripen, could definitely impact a "stable" ecosystem and I'd forgotten that the tropics do seem to have dry and wet seasons to complicate things.

I guess one way to look at this is to think of an ecosystem as an n-dimensional space, with each ecological niche in it being an m-dimensional subspace within it, such that n>m. Every species would be a point in the ecospace limited to one or perhaps multiple niches. To complicate things, the space is changing through time, and the species respond by branching off variants of themselves to abandon old niches as they become inhospitable, or to exploit new ones as they become available. I'm not necessarily talking geography and location here, or individual organisms, I'm referring to an abstract, conceptual space were coordinates represent the list of conditions peculiar to that niche and life forms form geometric shapes within it.

It might help to conceive of this mathematically, but actually modelling it that way far exceeds our capacity to do so. Still, even the simplest life-forms somehow manage to do this subconsciously without even thinking about it...they survive by navigating these n-dimensional manifolds, charting complex paths through them. "Primitive" man used to do this too, adding reason and communication with his fellows along with his memory of past events as tools to help plot his course. The old chief may have looked across the savannah and thought to himself, "I think this is going to be a dry year, perhaps game will be more plentiful further north."

This is all high-level organization arising out of the fundamental structure of matter and the laws and forces of physics, just like the shape of snowflakes is the result of the angle of the bend of the water molecule. I suspect the playing fields on other worlds like Gleise 581 may be very different to what we are used to, but I'd be willing to bet the rules of the game will somehow seem very familiar to us.