关键词: 叶片损伤, 植物功能性状, 植物防御性状, 植物生存策略, 植物性状权衡

Abstract: Aims Forest ecosystems are important barriers to global ecological safety. Leaf is the core organ for plant photosynthesis, its growth and damage directly affect forest ecological functions. This study explores the variations and trade-off strategies of traits by simulating leaf damage, revealing the different survival mechanisms of tree species. Methods This study focused on typical broad-leaved tree species in Northeast China, including the ashtree (Fraxinus mandshurica) and the Mongolian oak (Quercus mongolica Fisch. ex Ledeb.). By performing surgical cutting along the edge of the leaf, we simulated leaf damage to different degrees, namely no damage, mild damage, and severe damage under different growth stages (leaf expansion stage, leaf flourish stage, leaf falling stage), and systematically analyzed the response patterns of leaf growth traits, focusing on specific leaf area (SLA), chlorophyll content (Chl), and leaf nitrogen content (LNC), and leaf defensive traits, focusing on total phenols (TP), tannins (TA), and flavonoids (FLA) in leaf functional traits. And the trade-off relationships between traits and stress resistance strategies were explored. Important findings The results showed that: (1) The two tree species exhibit differences in their responses to mild damage: Fraxinus mandshurica can achieve compensatory growth by adjusting leaf growth traits such as SLA and Chl under mild damage, while Quercus mongolica shows no significant changes; Both tree species showed consistent performance under severe damage that choose the defense priority strategy, significantly reducing SLA content and increasing TP and TA content, supporting the growth defense trade-off theory; (2) During the leaf expansion stage, two tree species are more sensitive to damage manifested by significant fluctuations in Chl and SLA; During the leaf flourish stage, leaves mainly focuses on the accumulation of defensive substances, reflecting the resource allocation strategies of different growth stages; (3) There is a negative correlation between leaf functional traits (SLA, Chl, LNC) and leaf defense traits (TP, TA, FLA) in two tree species under damage, indicating that resource allocation mechanisms play a key role in the process of damage adaptation; (4) The Fraxinus mandshurica mainly promotes functional repair after damage by increasing Chl, while Quercus mongolica relies on the accumulation of chemical defense substances, reflecting the differences in growth defense trade-off strategies between the two species. This study provides a theoretical basis for revealing the survival strategies and stress resistance mechanisms of woody plants, and has some reference value for the prevention and control of leaf-fed pests and animals, as well as improving the ecological benefits of forests.

Key words: Leaf damage, Plant functional traits, Plant defense traits, Plant survival strategies, Plant trait trade-off