報告書番号

481007

タイトル（和文）

自然環境下におけるアカマツ生長量の変動－赤城山山麓の南向き緩斜面での調査－

タイトル（英文）

GROWTH VARIATION OF PINE TREE IN NATURAL ENVIRONMENT -CASE STUDY AT A SOUTH FACING SLOPE LOCATED ON THE FOOT OF MT.AKAGI-

概要 （図表や脚注は「報告書全文」に掲載しております）

赤城山山麓の南向き緩斜面（傾斜６度）のアカマツ林で毎木調査と土壌および林床植生の調査を行った。１）林分の高木はアカマツ，コナラ，スギから構成されており，その断面積比率は８４％，１３％，３％であった。２）林分の土壌の化学性は良好であり，場所による変動も小さかった。３）林床の植生にはササ型とモミジイチゴ型が存在した。４）アカマツの生長は斜面の上側でよくなる傾向にあり，下側では斜面と直交する方向での変動が大きくなっていた。５）アカマツ個体の生長には隣接樹林との位置関係が影響し，その場合，半径６ｍ以内の立木の影響が大きかった。６）アカマツ個体の生長を土壌の化学性，微地形，半径６ｍ以内の立木量，林床植生など１４個の変数を使って説明を試みたが，全変動量の２３％が説明できるに過ぎなかった。これらの変数のうち，半径６ｍ以内の立木量，表層土壌の炭素含有量，斜面上での位置などは無視できない要因であることが判

概要 （英文）

HEIGHT AND DIAMETER GROWTH WAS COMPARED IN SIDE A 0.3 HECTARE OF PINE STAND AT A SOUTH FACING DULL SLOPE(6 DEGREE)ON THE FOOT OF MT.AKAGI IN CENTRAL JAPAN. 1)PINUS DENSIFLORA,QUERCUS SERRATE,AND CRYPTOMERIA JAPONICA WERE DOMINANT AT TREE AND SHRUB LAYER ANDTHEIR TREE SIZE RANGED IN DBH FROM 10 TO 30CM FOR P.DENSIFLORA,5-15CM FOR Q.SERRATE,AND 5-10CM FOR C.JAPONICA.THE BASAL AREA FOR EACH SPECIESACCOUNTED FOR 84%,13%,AND 3% OF THE TOTAL BASAL AREA. 2)TWO TYPES OF FLOOR VEGETATION WERE RECOGNIZED FROM THE VIEW POINTS OF DOMINANT SPECIES,ONE TYPE WAS DOMINATED BY RUBUSPALAMATUS VAR.ERROMENA AND ANOTHER WASDOMINATED BY ARANDINARIA CHINO. 3)CHEMICAL PROPERTY OF SURFACE LAYER SOIL SHOWED TO BE IN FAVORABLE CONDITIONS COMPARED TO OTHER PINE FORESTS,AND SHOWED NO NOTABLE CHANGES AMONG 30 SUB-PLOTS. 4)COMPARING GROWTH RATE OF THE TREE HEIGHT AMONG SUB-PLOTS AT THE UPPER PARTS OF THE SLOPE AND SUB-PLOTS AT THE LOWER PARTS OF THE SLOPE,THE FORMER SHOWED HIGHER GROWTH RATE THAN THE LATTER.MORE GROWTH RATE VARIATION WAS RECOGNIZED AT THE LOWER PARTS WHERE GROWTH RATE WAS LOW ALONG WITH THE DIRECTION FROM EAST TO WEST. 5)AS FOR THE DIAMETER GROWTH,THE TRENDS ABOVE MENTIONED WERE RECOGNIZED. 6)THE TREES WHICH EFFECT THE GROWTH RATE OF A PINE TREE WERE ESTIMATED TO BE THE TREES STANDING WITHIN A CIRCLE OF 6M RADIUS. 7)RESULTS OF THE EXAMINATION OF GROWTH RATE OF INDIVIDUAL PINE TREE BY 14 FACTORS INCLUDING CHEMICAL PROPERTY OF SURFACE LAYER SOIL,MICRO-TOPOGRAPHY,STANDING POINT OF TREE,STANDING CROP OF NEIGHBOURING TREES WITHIN 6M RADIUS,AND FLOOR VEGETATION SHOWED THAT ONLY 23% OF THE TOTAL VARIATION OF GROWTH RATE WERE POSSIBLE TO EXPLAIN IN RELATION WITH THESESITE CONDITIONS.UNREMOVAL FACTORS WERE STANDING CROP OF NEIGHBOURING PINUS DENSIFLORA AND QUERCUS SERRATE WITHIN 6M RADIUS,STANDING POINT OF SAMPLED TREE MEASURED IN THE DIRECTION FROM SOUTH TO NORTH,AND CARBON CONTENTS OF SURFACE LAYER SOIL.

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