和歌山演習林におけるモミ, ツガ林の生産力調査 : 第1報 主としてモミ林について

Abstract

近年, 各樹種の林分現存量, 生産力などを調査した報告は数多くみられるが, 本報告は, 和歌山演習林のモミ, ツガ林を調査対象として, まず, モミの小径木を主に, その相対生長関係, 現存量, 林況などを調査したものである。調査は1966年8月に, 演習林内9林班, 11林班のモミ, ツガ林で行なわれた。調査結果をまとめるとつぎのようになった。1). 調査地の林況 9林班調査地では, 最上層林冠はシデ類, ヒメシャラが占め, 中層林冠には一部モミが生育し, 他は広葉樹類が占め, 最下層林冠をモミ, ツガが占めている (図-2)。11林班調査地は, スギ造林地内に介在して生育しているモミの純林分で, 小径の落葉広葉樹が数本まじっている (図-3)。モミの平均胸高直径10. 4cm, 平均樹高7. 6m, 樹齢は42 - 47年で, 林冠はうつ閉している。2). 調査林分の地表での相対照度は, 9林班は1. 7％, 11林班は1. 5％であった。3). 直径に対する幹, 枝, 葉の相対生長関係はつぎのようになり, 一部の相対生長関係にモミとツガで樹種差がみられた。logws=1. 37410gD_2_0. 3+1. 380 9林班, モミ, ツガ (図-6) logw_S=1. 014logD_2_0. 3+2. 103 11林班, モミ (図-6) logw_S=1. 117logD_2_1. 3+1. 879 9林班, モミ, ツガ (図-6) 1ogw_S=1. 074logD_2_1. 3+2. 060 11林班, モミ (図-7) logw_S=0. 914logD_2_0. 3+1. 507 9, 11林班, モミ (図-7) logw_S=0. 941logD_2_0. 3+1. 345 9林班, ツガ (図-7) logw_B=1. 255logD_2_0. 3+1. 143 9, 11林班, モミ, ツガ (図-9) logw_L=1. 173logD_2_0. 3+1, 186 9, 11林班, モミ, ツガ (図-10) logw_L=0. 919logD_2_1. 3+1. 625 9林班, モミ, ツガ (図-10) logw_L=1. 135logD_2_1. 3+1. 356 11林班, モミ (図-10) logw_L=1. 117logD_2_B+1. 532 9, 11林班, モミ (図-11) logw_L=1. 117logD_2_B+1. 356 9林班, ツガ (図-11) Iogw_LN=0. 937logD_2_0. 3+0. 277 9林班, モミ, ツガ (図-12) logw_LN=1, 162logD_2_0. 3+0. 385 11林班モミ (図-12) 4). モミ, ツガ林の現存量はha当り11林班では, 76. 9ton (幹乾重), 30. 4ton (枝乾重), 20. 8ton (葉乾重), 9林班では平均して32. 4ton (幹乾重), 14. 0ton (枝幹重), 9. 4ton (葉幹重) となった。5). 葉量と生長量の関係を求めると, 9林班と11林班で明らかな差がみられ, 同量の葉量に対する生長量は後者が3倍にも達している (図-15)。6). 本調査モミ, ツガの葉の平均純同化率 (a') と非同化器官の平均呼吸率 (R) は, a'_1=1. 100 - a'_2=0. 732g/g. year (11林班), a'_3=0. 534 - a'_4=0. 345g/g. year (9林班), R-0. 04g/g. yearとなり, 葉の平均純同化率は9林班と11林班で, 大きな差があらわれた。また, 9林班のモミとツガではとくに差がみられないようである。7). 全葉量に対する新葉量の比を求めると, モミは9林班では2. 5 - 13. 8% (平均7. 6％), 11林班では7. 2 - 14. 9％ (平均11. 5％), ツガは2. 2 - 8. 4％ (平均6. 1％)となった。8). 11林班の調査モミ林の年間の純生産量は乾重量で14. 35ton/ha, 9林班のモミ, ツガ林は0. 87 - 2. 13ton/haとなり, 後者は広葉樹類に被圧されているために, 葉量あたりの生産量は非常にすくない。

In recent years, many investigators have reported studies on the estimation of standing crop and productivity of forest stand. However, the studies on the Abies Juss. and Tsuga Carr. are very few. In this report, the authors deal with some investigations on the forest production of natural Japanese fir (Abies firma Sied. et Zucc.) and Japanese hemlock (Tsuga Sieboldii Carr.) stands in Kyoto University forest in WAKAYAMA (Lat. 30° 04' N, Long. 135° 30' E, Alt. 500~1200m). This investigation was carried out in compartment-9 and 11 of University forest in August, 1966. In sample stand of compartment-9 (9-stand), the crown of Japanese fir and hemlock was overspread with the broad leaved trees (Fig. 2), and sample stand of compartment-11 (11-stand) was pure Japanese fir forest (Fig. 3). The results obtained from this investigation were as follows: 1) In 9-stand, forest crown consisted of three stories. Over story; deciduous trees (Stewartia monadelpha S. et Z. and Carpinus spp.) Middle story; broad leaved trees (Ilex pedunculosa Miq. and Carpinus spp.) Under story; Japanese fir, Japanese hemlock and broad leaved trees And 11-stand was single storied Japanese fir forest. 2) The investigated Japanese fir stand in 11-stand was 42~47 years old and had closed crown. Its mean diameter breast high was 10. 4 cm, and mean tree height was 7.6 m. 3) Relative light intensity under forest crown was 1.7% in average in 9-stand and 1.5% in average in 11-stand. 4) Each allometric relation of weight of stem, branch and leaf to diameter was as follows: [Figure omitted] It seems that there is a difference between Japnese fir and Japanese hemlock in some allometric relations. 5) The estimated standing crop of Japanese fir in 11-stand per hectare was 76.9 ton (stem), 30. 4 ton (branch) and 20.8 ton (leaf) in dry weight, and in 9-stand, the standing crop of Japanese fir and hemlock per hectare was 32.4 ton (stem), 14.0 ton (branch) and 9.4 ton (leaf) in dry weight. 6) There was distinct difference between allometric relation of stem weight increment to leaf weight of Japanese fir in 9-stand and in 11-stand, and the increment per leaf weight in 11-stand was over three times as much as in 9-stand (Fig. 15). 7) In case of this investigation, net-assimilation rate of Japanese fir in 11-stand was estimated 1.100 (a'1)~0.732 (a'2) g/g･year, in Japanese fir and hemlock in 9-stand, its value was 0.534 (a'3)~0.345 (a'4) g/g･year. Mean respiration rate of non-assimilation parts of these species was 0.04 g/g･year in both stands (Fig. 16). 8) The dry weight of new leaf of Japanese fir was 2.5~13.8% (7.6% in average) of total leaf weight in 9-stand and 7.2~14.9% (11.5% in average) in 11-stand. In case of Japanese hemlock, dry weight of new leaf was 2.2~8.4% (6.1% in average) of total leaf weight. 9) The annual net production of Japanese fir in 11-stand was estimated to be 14.35 ton per hectare in dry weight and in Japanese fir and hemlock of 9-stand it was estimated that the value was 0.87~2.13 ton per hectare in dry weight. As Japanese fir and hemlock in 9-stand were suppressed by broad leaved trees, the annual net production per leaf weight was less than in 11-stand.