While ecosystems may be bound and individually discussed, they do not exist independently, but interact in a complex web.
The ecological relationships connecting all ecosystems make up the biosphere.
Thus, the "ecosystem" of our field mouse includes plants, and soil, and soil organisms—and of course other field mice to insure that mice will always be a part of that ecosystem.
And perhaps present are Bald eagles (Haliaeetus leucocephalus), dependent upon trees for nesting and roosting and a stream for water (and fish as an alternative food), feeding upon Field mice, recycling those that are caught into baby Bald eagles and droppings that are food for the plants and earthworms.
These are a few ways an ecologist would approach describing ecosystem structure based upon the plants and animals (and others) present in it.
In addition to the organisms themselves, there are components utilized by the organisms that comprise the resources of the ecosystem.
Biotic factors include plants, animals, and micro-organisms.
The non-living components of the environment are known as abiotic factors.
Non-living components include non-living resources, such as space, and the non-living physical characteristics of habitats that differ by location, such as elevation, temperature, and humidity.
We know and can observe that the organisms living in almost any ecosystem are not all identical individuals, but can be categorized into species (discussed previously in Chapter 9); and each species has a unique set of morphological, physiological, and behavioral attributes (see Chapter 3) that will determine how each individual functions within the whole.