Marx’s insights for ecology are many. The four “informal laws of ecology,” as Levi Bryant points out in his post on John Bellamy Foster’s Marx’s Ecology, are not one of them (let alone four). These “laws” have been making their rounds ever since biologist and eco-socialist (and one-time Citizens Party candidate for the U.S. presidency) Barry Commoner proposed them around 1970. Numerous iterations afterward have suggested three, four, or five such laws, with Greenpeace’s Declaration of Interdependence being particularly influential. I’m not aware of any scientific ecologists today who think of them as actual scientific laws, though others have been proposed for the science of ecology (see, e.g., here or Pierre Dansereau’s 27 laws of ecology). Foster’s point is that they are “informal,” and therefore intended to provoke thought, not to serve as a foundation for a science.
But let’s look at them, and then at Marx. The first of Foster’s (Commoner’s) “laws,” that “everything is connected to everything else”, is (as Levi points out) a platitude. It’s not wrong, but it doesn’t take us very far. (Except in the mystical experience, which has its place, and an inspirationally important one for many environmentalists; but let’s leave that aside.) The point it makes is intended as a corrective to the common-sense notion that things are simply what they are (people, animals, possessions, units of one thing or another, etc.) and that’s all. The law says that they aren’t just that: everything arises out of its own set of originating conditions, and passes away into other conditions, affecting other things in the process. Not everything directly affects everything else — that would be impossible, since two things that arise simultaneously but in different places don’t normally affect each other (unless by way of some “holographic universe” or superstring-like mechanism that scientists haven’t figured out yet). But if you traced the lines of causal connection from any thing in the universe, you could, in principle, trace it back/forward/across to anything else. That’s what the theory of evolution and the Big Bang both propose, and the science of ecology shares the supposition (though theoretical physicists may not): there is a single universe that has unfolded along a single (branching/diversifying/multiplying/expanding) trajectory, and everything in it is connected through this shared ancestry/descent/line of development. That’s all. The more pragmatic point (which was Commoner’s point) is that our actions have effects and that we normally don’t give them enough thought.