Very nice Bubbub!
I have some formal training in drawing, drafting and design, I can say I really appreciate your attention to the layering of the branches especially. It is clear you thought this out well and payed attention to having shadows and darker shading for the branches that appear in the background, as well as lighter shading to those in the foreground. You gave it a great natural complexity that trees tend to have, so great instincts with these! Great shading! It is captivating and interesting to look at. If I could improve upon anything, it would be to pay close attention to the natural tapering that happens with most trees branches where they generally start thicker at the base and then thin as they travel outwards/upwards (you've done fantastic with this on almost all of them, though there is one or two that gets a bit thicker in the middle. Because your composition is good, I really don't notice it much though, it is well executed, nice work! And keep going, you're doing great!
).
One thing we can tend to do as we continue to build drawing skill, is to be a bit reliant on outlines, so I wonder what would happen if you tried drawing several trees that had
no outlines? Yikes right? Lol. That was my reaction when asked to do that. Drawing instructors sometimes throw weird exercises like this at us, to get us to experiment, think, draw, and "see" in new and interesting ways. It feels a bit painful at first sometimes, but usually I learn an unexpected skill to add to my collection. Sometimes sketching shapes via shading and non-connected lines can bring a very organic flair to drawings (just as an experiment and fun practice more than anything else). The goal when trying experimenting like that is not to create an ideal or good outcome, it is just to put in extra hours of training our hands, brains, and eyes to coordinate beautifully and in new and different ways. They say that people's drawing skill improves incrementally with continued hours of practice and ive always found that to be true. So, that's generally what the goal is. Suddenly after putting in a certain amount of extra time and exploring new drawing strategies, our ability just clicks and goes up a notch and we experience an "Aha! This is awesome!" moment. You're already doing excellent with this, and making fantastic progress, keep up the good work and keep having fun with it!
Everyone brings such a fun and interesting style to their own work, it is a pleasure and an honor to have it shared with us. Thanks for sharing!