Functional traits reflecting responses and adaptations of plants to their environment can be used as a bridge between plants and the changes occurring in their environment. The analysis of the relationship between plant functional traits and environmental gradients present on hill slopes can improve our understanding of adaptation mechanisms of plant communities under different microtopographic habitats. In this paper, nine leaf functional traits of Acer mono individuals were studied on eight volcanoes in different historical years in Wudalianchi, China. The main leaf functional traits of volcanic plants on shady and sunny slopes were determined. A change in survival strategy and adaptation mechanisms of shady and sunny slope plants was found. The results were as follows: (1) The change of slope direction is an important reason for the difference of leaf functional characteristics of Acer mono. (2) The difference of leaf functional characteristics in volcanoes reflects their different resource environments. At the same time, the growth of Acer mono is mainly limited by nitrogen. (3) Leaf thickness had a significant positive correlation with leaf area between the north-south slopes and between volcanoes. There was a significant positive correlation between leaf thickness and specific leaf area between volcanoes, which is related to the self-protection of Acer mono under volcanic soil conditions. These results suggest that Acer mono can respond to its environment and adapt to express the best combination of functional traits. Acer mono individuals from volcanoes of different ages have increased carbon sequestration capacity, leaf dry matter content, leaf area, leaf thickness, nitrogen and phosphorus content, while also having reduced specific leaf area and nitrogen to phosphorus ratio as an adaptation to abundant light, low water content and poor soil nutrients.