The study looked at how different families of Liriodendron chinense trees grow in response to different levels of nitrogen. They found that some families grew better with more nitrogen, while others did better with less. Under low nitrogen levels, some families grew taller and had more roots to absorb nitrogen efficiently. Overall, some families were better at using nitrogen efficiently, while others were more sensitive to nitrogen levels. This shows that genetics play a big role in how these trees grow in different nitrogen conditions.