The rate of reforestation has increased all countries in the Southeast Asia region during the last 15 years. Simultaneously, the rate of forest destruction, forest exploitation, illegal logging, clear-cut forest areas, amended adverse sites, old agricultural lands, mine lands and post-wildfire areas, conversion of natural forests into plantations, resettlement areas, and other uses have also been increasing. There is also increasing concern that the planting stocks of reforestation program are not sufficient to sustain the production of timber and non-timber forest products (NTFPs) and promote forest conservation. Mycorrhizas play an important a role to increase plant growth, nutrient content and survival rates of forest tree species in temperate and sub-tropical region. However no information is available regarding the effect of mycorrhizas on growth of tree species in tropical rain forest forests. The objective of this thesis was to utilize mycorrhizal fungi for rehabilitation of degraded tropical rain forest in Indonesia. Several experiments were carried out to determine whether ectomycorrhizas (ECM) and arbuscular mycorrhizal (AM) fungi enhance mycorrhizal colonization, nutrient content, plant growth and survival rates of some tropical rain forest tree species in Indonesia under greenhouse, nursery and field conditions.

　　The families of tropical tree species used in the experiment were Dipterocarpaceae, Guttiferae, Thymelaeceae, Apocynaceae, and Verbenaceae and these families are important as they provide timber and NTFPs. The tree species were Shorea pinanga, S. seminis, S. balangeran (Dipterocarpaceae), Dyera polyphylla, Alstonia scholaris (Apocynaceae), Calophyllum hosei, Ploiarium alternifolium (Guttiferae), Aquilaria malaccensis, A. filaria, A. crasna, A. microcarpa (Thymelaeaceae) and Tectona grandis (Verbenaceae). ECM species were Pisolithus arhizus and Scleroderma columnare for S. pinanga and S. seminis . Four ECM species were Calvatia sp., Boletus sp., Scleroderma sp., and Strobilomyces sp for S. balangeran. P. arhizus and S. columnare were crushed and pelletized. The mycelium of ECM inoculum was grown in Pachlewski medium and mixed in sodium alginate. The inoculum paste was in calcium chloride solution to obtain a granular alginate inoculum. Inoculation of seedlings was carried out after germination. One tablet or two alginate beads was applied to a seedling of S. pinanga or S. seminis . For S. balangeran experiment, each of ECM fungal species was blended in distilled water. The spore suspension was applied to S. balangeran seedling. For AM inoculum, Glomus clarum, Gigaspora decipiens, Glomus sp. ACA, Entrophospora sp. and Glomus sp. ZEA were propagated in pot cultures. AM inoculation was placed five g of inoculum below seedlings. For ECM experiments, peat soil was sterilized by heating over a wood fire. Seeds of Shorea species were sown in peat soils and grown under shading net. In the field experiment, The S. balangeran seedlings were planted at a line spacing was 1 x 1 m. For AM experiments, an ultisol used was mixed with river sand and sterilized an autoclave. The seedlings were grown in a greenhouse. Shoot height, stem diameter, leaf number, shoot fresh and dry weight, nutrient content, total root lenght, mycorrhizal colonization and survival rates were measured 4-7 months after transplanting. After harvest, shoots and roots were separated. They were oven-dried and weighed. Ground shoots were digested with H₂SO₄ and H₂O₂ solution. N (Nitrogen) and P (phosphorus) concentration in the digested solution were determined by the semi-micro Kjeldahl method and vanadomolybdate-yellow assay, respectively. Survival rates (%) = number of viable seedlings / number of initial seedlings x 100. To calculate ECM colonization (%), the total number of root tips and the number of ECM short roots were counted under a dissecting microscope. To calculate AM colonization (%), the roots were stained and observed under a compound microscope. The percentage of AM fungi was estimated by scoring the presence or absence of AM structures.
The percentage of ECM colonization by S. pinanga and S. seminis was 35-86%. The colonization increased N and P content in both Shorea species. There was no difference in the percentage colonization between spore and mycelium inoculum nor between P. arhizus and S. columnare . Survival rates of S. pinanga and S. seminis were greater for inoculated seedlings than in control seedlings. A positive relationship was found between N or P content and shoot dry weight of S. seminis inoculated with both ECM fungi. The percentage of ECM colonization by S. balangeran was 59-67%. Colonization of S. balangeran increased shoot height, fresh and dry weight 6 months after transplanting under nursery conditions. The percentage AM colonization of D. polyphylla, A. filaria, C. hosei, P. alternifolium, A. crasna, A. malaccensis, A. microcarpa (WK), A. microcarpa (EK), A. scholaris and T. grandis ranged from 87-93%, 22-39%, 27-32%, 18-19%, 63-78%, 83-97%, 83-97%, 63-94% and 50-90%, respectively. Colonization by G. clarum and G. decipiens increased shoot height, stem diameter, and shoot and root dry weights of D. polyphylla and A. filaria seedlings. Shoot N and P concentrations of D. polyphylla and A. filaria seedlings were increased by AM colonization by as much as 70-153% and 135-360%, respectively. Colonization by G. clarum and G. aggregatum increased shoot height, stem diameter, leaf number, shoot and root dry weights of P. alternifolium and C. hosei , with the propagation cutting system. Shoot P content of P. alternifolium and C. hosei seedling were increased by AM colonization. Colonization by Entrophospora sp., G. decipiens, G. clarum, Glomus sp. ZEA and Glomus sp. ACA increased shoot height, stem diameter, fresh weight, dry weight, N and P content of A. crasna, A. malaccensis, A. microcarpa (WK) and A. microcarpa (EK) seedlings. Entrophospora sp. was more effective in improving N and P content, shoot height, stem diameter, fresh weight, dry weight of Aquilaria species than G. decipiens, G. clarum, Glomus sp. ZEA and Glomus sp. ACA. Moreover, AM colonization also increased total root length of A. scholaris seedlings 5 months under greenhouse conditions. The survival rates of D. polyphylla, A. filaria, C. hosei, P. alternifolium, A. crasna, A. malaccensis, A. microcarpa (WK), A. microcarpa (EK), A. scholaris and T. grandis ranged from 92-100%, 100%, 100%, 100%, 87-100%, 93-100%, 87-100%, 87-100%, 93-100% and 90-98%, respectively. In the field experiment, colonization by four ECM fungi increased shoot height and stem diameter of S. balangeran 40 months after transplanting in the degraded field. To summarize, the results of this study confirm that utilization of mycorrhizal fungi can increase plant growth, nutrient content and survival rates of some tropical tree members of the family Dipterocarpaceae, Apocynaceae, Guttiferae, Thymelaeaceae, and Verbenaceae under greenhouse, nursery and field conditions. In this study, some effective and suitable isolates of mycorrhizal fungi were found for inoculating in tropical tree seedling species, i.e. P. arhizus, S. columnare, Boletus sp. (ECM), G. clarum, G. decipiens , and Entrophospora sp. (AM). Inoculation is to be a promising way to optimize the production of vigorous seedling stocks species which are economically and ecologically important in the rehabilitation of degraded tropical forest lands in Indonesia.

（日本語訳）
森林減少の速度はここ１５年で東南アジアのすべての国で上昇している。 同時に森林破壊の速度、森林拡大、不法伐採、皆伐された森林の面積、不毛な地帯、古い農耕地、鉱山及び自然火災地域、 天然林の植林地への転換、再植民地域も増加している。 木材および非木材の生産を支え、森林の保全を進めるための森林再生プログラムの苗木が不十分であることにも関心が集まっている。 菌根は温帯及び亜熱帯の樹木種の成育、養分吸収及び生存において重要な役割を果たしている。
本研究の目的はインドネシアの荒廃した熱帯雨林の再生に菌根菌を用いることである。 苗床及び圃場条件下で外生菌根(ECM)及びアーバスキュラー菌根(AM)菌が熱帯雨林の樹種の菌根形成、養分吸収、 成育及び生存率を促進するかどうかを測定するために実験を行なった。

　供試した樹木の種は Shorea pinanga, S. seminis (フタバガキ科), Dyera polyphylla, Alstonia scholaris (キョウチクトウ科), Calophyllum hosei, Ploiarium alternifolium (フクギ科), Aquilaria malaccensis, A. filaria, A. crasna, A. microcarpa (ジンチョウゲ科) 及び Tectona grandis (クマツヅラ科)であった。 供試した外生菌根菌種はPisolithus arhizus と Scleroderma columnare . であった。 P. arhizus 及びS. columnare の子実体は粉砕し、小球にした。 外生菌根菌４種は、Calvatia sp., Boletus sp., Scleroderma sp., 及び Strobilomyces sp.であった。 外生菌根菌の菌糸体はPachlewski液体培地で成育させ、アルギン酸ナトリウム中と混合された。 発芽１０日目に苗への接種を行なった。 外生菌根菌接種源を苗に与えた。 アーバスキュラー菌根菌 Glomus clarum, Gigaspora decipiens, Glomus sp. ACA, Entrophospora sp. 及び Glomus sp. ZEA をトラップ培養により分離した。 アーバスキュラー菌根菌の接種源は苗の下に5 g与えた。 外生菌根の実験では泥炭土壌は火炎滅菌した。 滅菌した泥炭土壌500 gを含むポットに種子をまいた。 Shorea の種は遮光下で生育させた。 アーバスキュラー菌根菌の実験に使用した土壌はオキシソルで、川砂と3:1(v/v)で混合した。 ガラス室で１２０-１８０日間生育させた。気温は２６-３５℃で相対湿度は80-90%、明期は１２時間であった。 地上部の高さ、茎の直径、葉数、地上部新鮮重及び乾物重、生存率、菌根系率、根長及び養分吸収を移植１５０-２１０日目に測定した。

　外生菌根形成率はby S. pinanga と S. seminis で35-86%であった。 外生菌根形成は両Shorea種の窒素及びリン吸収を増加させた。 P. arhizus と S. columnare の間または胞子接種源と菌糸体接種源との間で菌根形成率に差はなかった。 S. pinanga と S. seminis の生存率は接種区で非接種区より高かった。 両外生菌根菌種で S. seminis の窒素またはリン吸収と地上部乾物重との間に正の相関関係が認められた。 D. polyphylla, A. filaria, C. hosei, P. alternifolium, A. crasna, A. malaccensis, A. microcarpa (WK), A. microcarpa (EK), A. scholaris 及び T. grandis のアーバスキュラー菌根菌形成率 それぞれ87-93%, 22-39%, 27-32%, 18-19%, 63-78%, 83-97%, 83-97%, 63-94% 及び50-90%であった。 G. clarum 及び G. decipiens の菌根形成は D. polyphylla 及び A. filaria の地上部の高さ、 茎の直径、地上部と根部の乾物重を増加させた。 D. polyphylla 及び A. filaria の地上部の窒素及びリン含有率はアーバスキュラー菌根形成により それぞれ70-153% 及び 135-360%増加した。 G. clarum 及び G. aggregatum の菌根形成は P. alternifolium 及び C. hosei の地上部の高さ、 茎の直径、葉数、及び地上部と根部の乾物重を増加させた。 P. alternifolium 及び C. hosei の地上部リン吸収はアーバスキュラー菌根形成により増加した。 Entrophospora sp., G. decipiens, G. clarum, Glomus sp. ZEA 及び Glomus sp. ACAによる アーバスキュラー菌根形成は A. crasna, A. malaccensis, A. microcarpa (WK) 及び A. microcarpa (EK)の生育と 養分吸収を増加させた。 Aquilaria の養分吸収と生育の改善において Entrophospora sp.は G. decipiens, G. clarum, Glomus sp. ZEA及び Glomus sp. ACAより効果が大きかった。 A. scholaris ではアーバスキュラー菌根菌は苗の窒素、リン、カリウム、カルシウム及びマグネシウム吸収を促進した。 アーバスキュラー菌根形成はガラス室条件で１５０日目に A. scholaris の根長を増加させた。 D. polyphylla, A. filaria, C. hosei, P. alternifolium, A. crasna, A. malaccensis, A. microcarpa (WK), A. microcarpa (EK), A. scholaris 及び T. grandis の生存率は それぞれ 92-100%, 100%, 100%, 100%, 87-100%, 93-100%, 87-100%, 87-100%, 93-100%及び 90-98%であった。 圃場では、外生菌根菌４種による菌根形成が移植４０ヶ月目にS. balangeran の樹高及び幹の直径を増加させた。 これらの結果はガラス室、苗床及び圃場において菌根菌がフタバガキ科、キョウチクトウ科、フクギ科、ジンチョウゲ科、 及びクマツヅラ科の熱帯樹種の生育と養分吸収を促進することを確認した。 本研究では P. arhizus, S. columnare, Boletus sp., G. clarum, G. decipiens , 及び Entrophospora sp. が効果のある最適な菌根菌の分離株であった。 接種はインドネシアの荒廃した熱帯林の再生において経済的及び生態学的に重要な樹種の生産を最適化する方法である。