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2008-2009年の芦生研究林上谷流域における11河川 (針広混交林10, スギ人工林1)の底生動物群集構造を報告し, 群集構造と森林環境との関係を考察した. その結果, 底生動物群集は (1)シカ食害・排除区の2次谷河川, (2)シカ食害区の1次谷河川, (3)シカ排除区の1次谷河川, (4)シカ食害区のスギ人工林1次谷河川の4 種類に類型化された. シカ食害区の1次谷河川の群集はスギ人工林1 次谷河川を除く他河川より多様度が低く, 細粒土砂に生息する底生動物に特徴づけられた. これらの結果は, シカ食害による土壌侵食を通じた河床細粒化に起因すると推察された. 一方, 2次谷河川の群集はシカ食害・排除区で類似し, 刈取食者, 捕食者に特徴づけられた. このことから, 2次谷河川は1次谷河川よりも付着藻類, 被食者が豊富な河川環境や, シカ食害による河床細粒化が起こりにくい強力な掃流力を有していると考えられた. また, スギ人工林1次谷河川の群集は破砕食者に特徴づけられた. 上谷流域における底生動物群集は, 河川サイズに応じて異なる河川物理環境や, 森林―渓流生態系のつながりを通じた森林環境の影響を良く反映し, それぞれで異なった構造の底生動物群集が成立していることが判明した., We reported the stream macroinvertebrate community structures in 2008-2009 in 11 streams (mixed forest: 10, Japanese cedar plantation: 1) belonging to Kamitani, Ashiu Research Forest, Kyoto, Japan, and discussed the relationships between the community structures and forest environments. Macroinvertebrate communities were classified into four groups; (1) second-order streams at deer-excluded and deer-grazed sites, (2) first-order streams at deer-grazed site, (3) first-order streams at deer-excluded site, and (4) first-order stream at cedar plantation with deer. Under deer overbrowsing, macroinvertebrate communities in first-order streams showed lower diversity than those in the other streams, and were characterized by a dominance of burrower taxon. These results might be attributed to fine sedimentation via soil erosion caused by deer overbrowsing. On the other hand, in second-order streams, macroinvertebrate community structure was similar between the deer-excluded and deer-grazed sites, and the community was characterized by dominance of grazer and predator taxa. These results suggest that second-order streams have abundant periphyton and prey items, and strong tractive force which might wash out fine particles more effectively compared to those of first-order streams. In cedar plantation, macroinvertebrate community in first-order stream was characterized by dominance of shredder taxa. In conclusion, macroinvertebrate communities in Kamitani showed different structure patterns in relation to physical environment (i.e., stream size), and forest environment through forest-stream ecosystem.