.林草间作系统根系结构研究.docVIP

桉树林草间作系统根层结构的研究 白昌军 虞道耿 陈志权 刘国道 (中国热带农业科学院热带作物品种资源研究所/ 农业部华南作物基因资源与种质创制重点实验室，海南儋州 571737) 摘要：我国桉树人工林面积超过150万hm2，为世界第二植桉大国，但桉树人工林单一种植和连栽引起的人工林植被多样性降低、土地退化等环境问题普遍存在，桉树人工林间作成为恢复与重建桉树林下植被多样性的重要途径。采用壕沟法开展6a龄桉树人工林12个牧草间作3a后间作系统根层结构研究，结果表明：间作牧草3a后桉树根系主要分布在距树基50cm～100cm的行间，分布了桉树75.95%的根系，距树基越远根量越少，间作禾本科牧草限制了桉树根系向行间(4m) 伸展，而间作豆科牧草促进了桉树根系向行间伸展。桉树根系主要集中在10cm～50cm的土层，占总根量的74.81%，间作禾本科牧草抑制了桉树根系向浅层分布的可能，而间作豆科牧草后桉树根系向土壤中上层扩展，且更加集中在20cm～40cm土层。间作牧草与桉树根系在水平分布和垂直空间上不重叠、呈互补性分布有利于充分利用林间土地资源而减少对水分和养分的竞争，有利于植被多样性的形成。 关键词：刚果12号桉；林草间作系统；根系结构；豆科牧草；禾本科牧草 A Study of Root Structure for Eucalyptus Silvopastoral Systems BAI Chang-jun, YU Do-geng, Chen Zhi-quan, LIU Guo-dao (Tropical Crops Genetic Resources Institute, CATAS/Key Laboratory of Crop Gene Resources and Germplasm Enhancement in Southern China, Ministry of Agriculture,Danzhou,Hainan 571737) Abstract: Eycalyptus plantation has been planted morn than 1,500,000ha and China has be coming the second biggest Eucalyptus plantation country in the world, but poor biodiversity of understory vegetation and land degradation has become a teething problem for its sigle and continuous-planting rotations in Eucalyptus plantation and intercropping is the important way to retorate and reconstruct biodiversity of Eucalyptus plantation. The foss moat were adapted to measure root systems structure of silvopastoral after intercropping with 12 varieties forages 3 years later under Eucalyptus plantation, which planted morn than 6 years. The preliminary results show that pure Eucalyptus roots distribute the most root biomass at 50cm～100cm apart from Eucalyptus basal in horizontal distribution and 75.95% of total root from 0-80cm soil layer in pure plantation, the distribution rate changed after intcropping, intercropping grasses limit Eucalyptus root extent to interval of Eucalyptus rows and legumes promote the Eucalyptus root extent to the interval of Eucalyptus rows. Eucalyptus roots mainly concentrated in 10～50cm deepth soil layer in vertical structur