Abstract: The vegetation characteristics and disturbance regime of 40 Larix principisrupprechtii canopy gaps and 40 non-gaps were studied by using the line transect method in Pangquangou National Nature Reserve of Shanxi. In total, 72 species of seed plants, belonging to 53 genera and 22 families were recorded. The species diversity of canopy gaps and nongaps, gaps of various areas, gaps in different stages of development were analyzed through R language. The results showed that: (1) The flora genus and dominant species changed obviously in canopy gaps compared with that in non-gaps. The regeneration of L. principisrupprechtii belonged to the way of canopy gaps. (2) Shannon index (H), Pielou evenness index (J), Patrick richness index (S), ecological dominance (λ) and comprehensive diversity index (Z) in canopy gaps were significantly greater than those in non-gaps (P<0.05). (3) The distribution of H, J and Z followed a unimodal curve with the increase of canopy gap size, and H, J and Z achieved the maximums when the canopy gap sizes were 240-320 m2. (4) In the first 10 years after the formation of gaps in L. principisrupprechtii plantation, the values of H and Z in the tree and shrub layers were low. After approximately 20 years, both H and Z reached their maximums. The H value in the shrub layer achieved its maximum between 10-20 years. (5) H, J, S, λ and Z indexes showed significant differences among different gap sizes and at different developmental stages.

Key words: nutrient uptake, nutrient utilization, intercropping advantage, maize and potato intercropping