報告書番号

U01020

タイトル（和文）

イヌワシを頂点とする生態系の解明 -－秋田駒ヶ岳のイヌワシ行動圏におけるノウサギの植生利用と生息密度の予測－-

タイトル（英文）

Study on the ecosystem sustaining a pair of Golden Eagles.-Vegetation usage and density forecast of Japanese hare Lepus brachyurus in the home range of a pair of Golden Eagle on Mt. Akita-Komagatake-

概要 （図表や脚注は「報告書全文」に掲載しております）

秋田駒ヶ岳山麓のイヌワシを頂点とする生態系のなかで，ノウサギの生息に必要な群落の属性（林床植生や森林構造）を明らかにすることを試みた．あわせて，植生環境からノウサギの生息密度をどの程度予測できるかを検討すした．その結果，ブナ林，スギ林など異なる様々な植生タイプを含んだデータでは，林床植生によるノウサギ生息密度の予測は困難なことがわかった．そこで，林冠構造の均質なスギ植林のみで解析を行ったところ，草本植物のVI（VI: Volume Index =Σ被度(％)×平均高(cm)）と全天写真で解析した林冠閉鎖度によってノウサギ生息密度を予測できることがわかった．また，スギ植林の森林属性（群落高，幹の平均直径など）との対応でも，スギの密度，直径，胸高断面積合計，林冠閉鎖度でノウサギの生息密度を予測できる可能性が確かめられた．以上の結果から，異なる群落タイプにわたってノウサギの生息密度と相関のある属性は見いだせなかったものの，森林ごとに林冠構造の均質なスギ林においては林冠閉鎖度や草本の体積を指標するVIなどでノウサギの密度を予測できる可能性があることがわかった．

概要 （英文）

This study aims to clarify how can Japanese hare (Lepus brachyurus) densities be forecasted in some vegetation types.It was clarified that hare densities were higher in open canopy habitats like a cleared section of artificial forest with pellet count method. When we examined the relationships between hare density and various attributions of forest floor vegetation, however, no vegetation factors had statistically significant correlation with hare density. Multi correlation analysis also showed low multiple correlation coefficient. Thus it seemed to be difficult to predict hare density with forest floor vegetation including various forest types.Only in seven planted Cryptomeria japonica forests, on the other hand, herbs' volume index and canopy cover degree calculated from fisheye lens photographs had significant correlation with hare density. In the planted forests, hare density was higher in young forests from examination of the relationship among some forests' attributions as stand height, density, mean DBH, basal area and hare density. There were much volume of herb and/or shrub biomass, which mean hares' food and shelter from predators, in younger forests with low stand height, mean DBH, and basal area. It would be reason why there were high densities of hare in younger forests.

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