7 research outputs found
未熟練林業労働者における枝打ち作業の強度と功程(B. 生活科学)
3人の未熟練林業労働者を被験者とし, 実験室でステップテストを行ない, 各人における心拍数と酸素摂取量およびエネルギー消費量の関係を求めた。次に, 山林において一定時間ずつ, 鉈および鋸を用い, 地上から手の届く範囲で枝打ちを行なわせ, 用具別の枝打ち本数を計数するとともに, その間の心拍数を1分ごとに記録し, ステップテストの結果を用いて作業強度を計算した。鉈および鋸を用いた枝打ち作業の酸素摂取量の, 3人の被験者全員における平均値は, それぞれ21.7および23.3ml/kg/min, RMRについては5.34および5.81であった。これは, 熟練者の梯子を用いた作業に匹敵するかまたはそれ以上の強度に相当した。単位時間当たりの酸素摂取量は, 鉈を用いた作業の方が鋸よりも6.9%小さく, 枝打ち1本当たりの酸素摂取量は, 鉈の方が鋸より8.7%大きかった。これは, 未熟練者にとって鉈の方が操作がむずかしく, 思い切って力を込めることができず, 結果として作業に時間がかかるためで, 単位時間当たりの枝打ち本数は, 鉈を用いた作業は鋸に対し14.5%小さかった。作業強度は鋸の方が鉈より大きかったが, その差は酸素摂取量にして1.6ml/kg/min, RMRで0.47と, 生体にとってわずかな差にすぎなかったので, 作業の能率からみて, また, 樹幹に傷をつけたり作業者が怪我をする可能性が鋸において低いこともあわせ, 未熟練者が枝打ちに用いる用具としては, 鉈より鋸の方が適当である。To assess both work intensity and operational efficiency of pruning with hatchets and saws by unskilled forest workers, heart rate of 3 subjects while at pruning with each tool were measured with portable heart rate recorders continuously and the numbers of branches pruned were counted. And to evaluate work rate from heart rate response, relationships between heart rate and O_2 uptake, heart rate and energy expenditure were measured simultaneously applying a step test on each subject, then the intensity of pruning work with each tool was estimated from the relationships. The mean values observed for O_2 uptake during hatchet and saw work were 21.7 and 23.3ml/kg/min, respectively, and for RMR, 5.34 and 5.81,respectively. But pruning speed of hatchet work was 14.5% smaller than that of saw work. The difference in work intensity with each pruning tool was not great, but saws were superior to hatchets for unskilled forest workers from the viewpoint of pruning speed
作業対象物の身体に対する高さと作業強度の関係(B. 生活科学)
4人の被験者に実験室において, 測量用のポールを立木に見立て, 床から40cm, 120cm, 200cmのところにそれぞれ枝があるものと想定し, 鉈および鋸を用いて枝打ち模擬動作を行わせ, その際の酸素摂取量と心拍数を測定した。同じ被験者についてステップテストを実施し, 心拍数に対する酸素摂取量の回帰直線を求めた。枝打ち模擬動作の酸素摂取量と心拍数は, 高さ120cmと40cm, および120cmと200cmにおいていずれも有意差があり, 経験的に作業しやすい高さとそうでない高さの動作間には, 単にそのような感覚の差だけでなく実際の作業強度に差のあることが明らかとなった。実際の枝打ちと異なり模擬動作の強度はかなり低く, このような場合ステップテストによって求めた回帰直線をそのまま適用することはできないという著者の報告があらためて確認された。しかし, 枝打ち模擬動作の際の酸素摂取量と心拍数の間には有意な相関があり, 心拍数によって作業強度を評価できることが明らかとなった。To investigate the difference of work intensity of varied work height, 4 male subjects performed sham pruning in the laboratory with a hatched and a saw. A surveying pole was supposed to be a tree with branches at the height of 40,120,and 200cm. Oxygen uptake and heart rate of each work were measured. Both in 2 measured items, statistically significant difference was observed between the work height of 120 and 40cm, 120 and 200cm, respectively. On the whole, correlation of oxygen uptake and heart rate was significant, too. At the same time, step tests were performed and regression line of oxygen uptake on heart rate of each subject was obtained. Oxygen uptake during sham pruning estimated by these regression lines was significantly larger than the measured value, because oxygen uptake during sham pruning was considerably lower than that of stepping exercise. However, work intensity of these low activities was able to be assessed by heart rate
枝打ち機械を使用する作業の強度(B. 生活科学)
3人の林業労働者について, 枝打ち機械を使用した作業中の心拍数を連続測定し, 同時にステップテストによって心拍数とエネルギー消費量等の関係を測定して作業の強度を求めた。1人1台, 2人3台, 1人2台の機械使用作業それぞれについて, 最大酸素摂取量に対する酸素摂取量の割合は44.2±8.9%, 52.9±9.5%, 62.3±11.4%, エネルギー消費量は5.09±1.23kcal/kg/h, 6.20±1.32kcal/kg/h, 7.36±1.61kcal/kg/h, RMRは4.0±1.3,5.0±1.3,6.2±1.7であった。1人で1台の枝打ち機械を使用した場合の作業強度は手作業より低く, 2人3台で手作業とほぼ等しく, 1人2台では手作業より高く, 無酸素性作業閾値付近を前後する激しい労働であった。枝打ち機械を改良して上昇速度を速くすれば作業功程が改善されるが。労働強度が増加するので, 同時に機械の軽量化が必要である。枝打ち作業に従事すれば, 機械を使用した作業でも手作業でも, その生活は, 第三次改定日本人の栄養所要量による生活活動の強度4段階のうち一番強度の高い, IV(重い)に位置づけられる。Work intensity of 3 forest workers during work with pruning machines were measured with portable heart rate recorders continuously under 3 levels of work load, i. e. 1 machine per 1 person, 3 machines per 2 persons and 2 machines per 1 person. To assess work rate from heart rate response, relationships between heart rate and 0_2 uptake and energy expenditure were measured simultaneously applying a step test on each subject. Then work intensity of each subject was estimated from the relationship between heart rate and 0_2 uptake. The work intensities observed during 1 machine per 1 person, 3 machines per 2 persons and 2 machines per 1 person, were 44.2±8.9,52.9±9.5 and 62.3±11.4% of VO_2 max, respectively. Energy expenditures of those groups were 5.09±1.23,6.20±1.32 and 7.36±1.61 kcal/kg/h, and those of RMR were 4.0±1.3,5.0±1.3 and 6.2±1.7. The work intensity of forest workers engaging in pruning work, both with machines and manually, corresponds to IV (heavy) in the Japanese Recomended Dietary Allowances, i. e. grade of the most highest class
Boom and bust of a moose population – a call for integrated forest management
This is the postprint version of the article. The published article can be located at www.springerlink.comThere is increasing pressure to manage forests
for multiple objectives, including ecosystem services and
biodiversity, alongside timber production. However, few
forests are currently co-managed for timber and wildlife,
despite potential economic and conservation benefits. We
present empirical data from a commercial Norway spruce
(
Picea abies
) and Scots pine (
Pinus sylvestris
) production
system in southern Norway in which moose (
Alces alces
)
are an important secondary product. Combining long-term
hunting and forestry records, we identified temporal vari-
ation in clear-felling over the past five decades, peaking in
the 1970s. Herbicide treatment of regenerating stands and a
fivefold increase in moose harvest has lead to a reduction in
availability of successional forest per moose of
[
90 %
since the 1960s. Field estimates showed that spraying with
the herbicide glyphosate reduced forage availability by 60
and 96 % in summer and winter, respectively, 4 years after
treatment. It also reduced moose use and habitat selection
of young spruce stands compared with unsprayed stands.
Together these lines of evidence suggest that forest man-
agement led to an increase in moose carrying capacity
during the 1970s and a subsequent decline thereafter. This
is likely to have contributed to observed reductions in moose population productivity in southern Norway and is
counter to sustainable resource management. We therefore
call for better integration and long-term planning between
forestry and wildlife management to minimise forest
damage and the development of large fluctuations in
ungulate populations
立木に直登する機械のマイクロプロセッサによる制御(B. 生活科学)
A microprocessor assisted automatic control equipment for the machine which climbs up a tree in a straight line was developed. The machine consists of 2 grasp units and 1 expansion and contraction unit, and operates by 3 motors and is controlled by 4 switches. To control this machine, it is essential that grasp and opening, expansion and contraction should be repeated systematically, as a man climbs controlling his upper and lower limbs. Accordingly, to execute the routines of the controller one after another, termination of above-mentioned 4 actions were detected by the intensity of electric current, the time elasped or the state of microswitches. The developed control equipment was copmosed of a very simple circuit, but by only one stroke of its function switch, the climbing machine could automatically perform the function, i.e. ascent, stop, descent or grasp units opening, reliably. Consequently, the machine which climbs up a tree in a straight line approached almost the stage of practical use