Very good question! I've often wondered how to differentiate between shadow and color in a black and white drawing -- hope someone has an answer. Your log is beautifully rendered, and I think you could have gone even darker in some sections.
Nature journaling combines many of the activities I enjoy most -- birding, being in nature, walking, and drawing. But it was the intense sense of engagement that caused me to fall in love.
I am comfortable drawing from a photo, but prefer the experience of nature journaling in person because of the profound connection I feel to a place and object when I am directly observing.
I was happy with the drawing, but didn't know how to differentiate the colors when it came to watercolors.