Regeneration just after clear cutting at Sugi(Cryptomeria japonica) and Hinoki(Chamaecyparis obtusa) plantation Seiji Ishibashi, Toshihiro Saito, Kazuya Omura and Haruo Sawada (University Forest in Chichibu, The University of Tokyo) Introduction Result (Number of seedlings) The area of plantation in Japan is about ten million hector and many of them has U = Species which grow upper layer grown thirty to fifty years old that reached the age for cutting. However, many forest SU = Species which grow sub-upper layer owners don't want to cut their forest because low price of timber and difficulty of S = Species which grow shrub layer regeneration by planting. Some of them plan to try naturally regeneration after clear C = Conifer species cutting. In this study, we discuss about possibility of early natural regeneration just CL = Climber species after clear cutting at conifer plantation. 160 160 40 140 140 35 120 120 30 100 100 25 80 Study Site 80 20 60 15 60 40 10 40 number trees of per plot number of trees per plot per trees of number number trees plot of per 20 The study site is located at compertment no.3 at University Forest in Chichibu, 5 20 0 0 0 ～10 11～20 21～30 31～40 41～50 51～60 61～100 101～ ～10 11～20 21～30 31～40 41～50 51～60 61～100 101～ ～10 11～20 21～30 31～40 41～50 51～60 61～100 101～ The University of Tokyo. This site was 87 years Sugi (Cryptomeria japonica) and height class (cm) height class (cm) height class (cm) lower site, after site preparation, Sep. 2002 Hinoki (Chamaecyparis obtusa) plantation and clear cut in 2001. We set 6 plots upper site, after site preparation, Sep. 2002 middle site, after site preparation, Sep. 2002 U SU S C CL (5m×5m) in study site and checked regenerated seedlings in spring and autumn of U SU S C CL U SU S C CL 160 40 2002, 2003 and 2004. Each 2 plots are located at upper, middle and lower site of 160 140 35 140 120 slope and one of each is located at after site preparation and another at no 30 120 100 25 preparation. We got sample of soil from each plot for checking the buried seed and 100 80 20 80 60 set seed traps near each plot for checking the seed from another forest. 15 60 10 40 40 number trees of per plot number trees plot of per number of trees per plot per trees of number 20 20 5 University Forest in 0 0 0 Chichibu ～10 11～20 21～30 31～40 41～50 51～60 61～100 101～ ～10 11～20 21～30 31～40 41～50 51～60 61～100 101～ ～10 11～20 21～30 31～40 41～50 51～60 61～100 101～ height class (cm) height class (cm) height class (cm) lower site, agter site preparation, Jun. 2003 upper site, after site preparation, Jun. 2003 middle site, after site preparation, Jun. 2003 U SU S C CL U SU S C CL U SU S CL 30 60 25 5 50 20 4 40 Location of University Forest in Chichibu 30 15 3 20 10 2 number of trees per plot per trees of number number of trees per plot per trees of number 10 5 number of trees per plot per trees of number 1 0 0 0 ～10 11～20 21～30 31～40 41～50 51～60 61～100 101～ ～10 11～20 21～30 31～40 41～50 51～60 61～100 101～ ～10 11～20 21～30 31～40 41～50 51～60 61～100 101～ height class (cm) height class (cm) height class (cm) upper site, no site preparation, Sep. 2002 middle site, no site preparation, Sep. 2002 lower site, no site preparation, Sep. 2002 U SU S C CL U SU S C CL SU S CL 30 60 5 25 50 4 20 40 3 15 30 2 10 20 number of trees pre plot pre trees of number number of trees per pkot per trees of number number of trees per plot per trees of number 1 5 10 0 0 0 ～10 11～20 21～30 31～40 41～50 51～60 61～100 101～ ～10 11～20 21～30 31～40 41～50 51～60 61～100 101～ ～10 11～20 21～30 31～40 41～50 51～60 61～100 101～ height class (cm) height class (cm) height class (cm) middle site, no site prelaratioon, Jun. 2003 lower site, no site preparation, Jun. 2003 upper site, no site preparation, Jun. 2003 U SU S C CL U SU S CL Location of Study Site U SU S C CL Result 2 (Comparison of species composition) Discussion Species composition of seedling, burried seed and drift seed Seedling Seedling Burried Burried Type Species Drift seed Type Species Drift seed after site no site seed after site no site seed preparation preparation preparation preparation In September 2002, height class distribution showed inverse J shape in every plots. In June 2003, inverse J shape distribution was kept in after site Carpinus laxifolia ・○Pieris japonica ・ Carpinus tschonoskii ○ Schzophragma hydrangeoides ・ Fagus japonica ・ Deutzia crenata ・ preparation plots. However, in no site preparation plots, peak of distribution Betula maximowicziana ◎ Hydrangea ecscanden ・ Prunus grayana ・・ Viburnum dilatatum ・・ moved to upper height class. Betula schmidtii ○ Pourthiaea villosa var. laevis ・ Cersidiphyllum japonicum ○ Clerodendron trichotonum ・・ Phellodendron amurense ・・ Rubus crataegifolius ☆●○ From the results of comparison between September 2002 and June Carpinus japonica ○ Lindera umbellata ● Castanea crenata ・ Hydrangea hirta ・● 2003, in after site preparation plots number of trees were decreased and in Ｓ Zelkova serrata ○ Zanthoxylum piperitum ・・ Ｕ Fraxinus spethiana ○ Enkianthus moctsudai ・ no site preparation plots didn’t change. However, proportion of small sized Betula platyphylla ○ Pertya glabrescens ・ Evodiopanax innovans ・ Hydragea paniculata ・ trees (less than 10cm in height) were decreased in no site preparation plots. Betula ermanii ● Buddleja japonica ●・● Euptelea polyandra ●・○○ Cladrastis platycarpa ・・ Cornus confroversa ・・ Dentzia scabra ・ Most of species that we found in seedlings were quite simuler that we Quercus mongolica var. grosseserrata ・・ ○Lallicarpa japonica ・・ Betula grossa ○● Rubus palmatus var. coptpphyllus ・● found in buried seeds. The effects of drift seeds for regeneration of just after Acer cissifolium ・・ ●Kerria japonica ・ Acer nikoense ・ Cryptomeria japonica ◎・☆○ Alnus firma ○ Ｃ Chamaecyparis obtusa ●・◎○ cutting are not so big. Fraxinus lanuginosa ・ Tsuga sieboldii ○ Ilex macropoda ・・○ Actinidia arguta ・・ Fraxinus lanuginosa var. lanuginosa ・○Celastrus orbiculatus ・・ However, the number of buried seed is not big in conifer plantation, then ＣＬ Meliosma myriantha ・・ Ampelaopsis brevipedunculata ・・ Pterostyrax hispida ・・ ○Vitis coignetiae ・・ regeneration just after clear cutting on conifer plantation is not so easy. ＳＵ Acer micranthum ・・ ☆ Aralia elata ☆・○ Rhus javaniea ◎・○ Styrax obassia ・・ Clethra barbinervis ・●○ note : Symbles meen amout of seeds of seedlings Sedling ☆：n ≧ 50以上, ◎：50 ＞ n ≧ 30, ●：30 ＞ n ≧ 10, ・：10 ＞ n Burried seed ☆：n ≧ 50, ◎：50 ＞ n ≧ 30, ●：30 ＞ n ≧ 10, ○：10 ＞ n Drift seed ☆：n ≧ 200, ◎：200 ＞ n ≧ 100, ●：100 ＞ n ≧ 50, ○：50 ＞ n.