Abstract:

The effects of gap size, gap age and canopy openness on Pinus yannanensis regenration were investigated with 65 gaps in virgin old\|growth P. yunnanensis forest in Panzhihua, Sichuan Province. The results showed that gap disturbance promoted P. yunnanensis regeneration. Regeneration densities of seedlings peaked in small gap, while saplings and mature trees peaked in large gaps. The gap age also played a role, that is, seedlings and saplings density peaked in young gaps, and mature trees peaked in mature gaps. Canopy openness had significant effects on P. yunnanensis regeneration. Seedling regeneration density decreased with an increase of canopy openness, while saplings and mature trees increased with canopy openness broadened. P. yunnanensis of natural regeneration was stronger in gaps with large canopy openness, whereas it was difficult for P. yunnanensis to regenerate in gaps with low canopy openness (<0.6). The P. yunnanensis were listed as the most importance value both in gaps and nongap, indicating P. yunnanensis will be the dominant species in this area in the future. 

Key words: gap regeneration, Pinus yunnanensis, canopy openness, mountainous area of southwestern Sichuan