Spatial Distribution Patterns of Regenerating Quercus wutaishanica- Pinus tabulaeformis in Relation to Topographic Factors in the Lingkong Mountain

This study aimed to thoroughly understand the renewal characteristics of dominant species in plant community, and to provide scientif ic basis for natural regeneration of coniferous and broadleaved mixed forest. We studied the spatial distribution patterns of regenerating Quercu wutaishanica and Pinus tabulaeformis and its relation with topographic factors using continuous quadrat method in a 4- hm2 sample plot in the Lingkong Mountain of Shanxi Province. It was found that the diameter-class structure was similar for both Q. wutaishanica and P. tabulaeformis, where most individuals were small and medium in size. Q. wutaishanica showed notable bottleneck phenomena among the individuals of 4-cm DBH, while P. tabulaeformis were all in growth state. For both species the seedlings outnumbered the saplings and the individuals in both age classes clustered only in small scale(0-5 m), but randomly distributed in larger scales. No obvious correlation was observed between the regenerating seedlings and saplings within and between the species. Most renewed seedlings and saplings of Q. wutaishanica grew in shady or semi-shady slopes, but those of P. tabulaeformis grew in semi-sunny slopes. The highest density of young trees was found in the slope of 20-30 degrees for both species. In Q. wutaishanica the altitude was positively correlated to seedling abundance(r = 0.152,P 0.01) but negatively to saplings(r =-0.102,P 0.05). However, no such correlation was observed in P. tabulaeformis. These results showed that the spatial distribution of regeneration of Q. wutaishanica and P. tabulaeformis is mainly of random patterns. The slope-exposure is obviously different between the two species in regeneration. The gradient factor,which is determined by the topographic preference of the species, inf luences the abundance and density of species to a certain degree, but has no obvious stimulative or depressive effects on regeneration of the two species.Fig 5, Tab 3, Ref 29