Our Nature-Study/ Spirituality Flowchart refers a great deal to Nature, but the concept of Naturalist Jim Conrad, who developed the flowchart and this website, may be different from yours.
To Jim, Nature is everything -- all the Universe's phenomena, material and non-material. Therefore, Nature includes new cars, plastic cups, garbage dumps, mentality, emotions, and whatever else is part of the Universe. This is not a particularly strange notion. Throughout most of the history of the human species, probably very few people if any thought that there might be anything "unnatural." Many great philosophers, such as Leibniz, Hegel, Schopenhauer, and Spinoza, have asserted the same idea. For Spinoza, Nature = God, and more and more thinkers who have a need to use the word "God" instead of "Creator," the "One Thing," "Great Spirit," and such, say the same.
Nature being everything means that when we "study Nature" we might be studying anything. In Jim's life, studying Nature meant paying close attention to living things and their ecology. But if the same effort had been made to pay close attention to music, history, the sociology of a community, the growth of a child to maturity, math, astronomy -- any complex system the understanding of which is evolving and can be conceived in different ways -- they all would have led to higher levels of spirituality.
What's important is to pay attention to something, digging ever deeper into it over a long period of time, every day struggling to think and feel in new-to-you ways about it.
But, note: When you choose your topic, you should "know yourself." You should be quite sure that your topic matches your natural predispositions and talents, so that as you pay attention, it'll feel right to you.