Keizo Tabata

Dead forms of canopy trees and regeneration process in Tadasu-No-Mori Forest

ギャップ更新の視点から，下鴨神社糺の森において林冠木の枯死形態と跡地への木本実生の侵入と定着の状態について調査を行い，各樹種の更新状況を検討した。その結果，林冠木の枯死形態はその後の実生の定着に影響をおよぼしてはいなかった。林床で見られた実生のうち，シュロの個体数が最も多く，また高木性樹種ではアラカシの実生が多数みられた。このことから今後アラカシが高木層の優占種となる可能性が高いと考えられた。林冠層での優占種ニレ科樹木では，ムクノキ，ケヤキで実生個体数が少なく，最優占種であるクスノキの実生密度も低い値であった。これは林冠木の枯死跡地であっても，その天空率の平均値が非常に低いことが理由として考えられた。

Simulation Model of Size Frequencies of Saplings in Restored Natural Habitat in Urban Area by Using Exponential Distribution

The population dynamics of saplings taller than 50cm were investigated from 1998 to 2003 in every year in the whole 6048m² area of the restored natural habitat Inochi-No-Mori in Kyoto city. There were 1249 saplings in the area in 2003. Population density was 32.2 individuals / 100m². Celtis sinensis formed 32.3% of the total number of individuals and was dominant species of Inochi-No-Mori. Only 126 saplings had been dead from 1998 to 2003 , so mortality rate was very low. We examined the height growth characteristic of saplings. As a result, there were size dependencies on the height growth of saplings. So we approximated the height distributions of saplings by exponential functions. By using this model, simulation about the height growth of each sapling was conducted in assuming that mortality rate and number of recruitment individuals was constant. We got the calculated size distributions from 1999 to 2003 and compared the calculated size distributions with the observed ones. As a result, differences between the observed size distributions and the calculated ones were very slight. This model predicted that the frequency of saplings taller than 500cm would be highest in 2015. The simulation was very valid for predication dynamics of saplings.