种子所处凋落物位置对杉木幼苗出土和早期生长的影响

Effects of seeds and litter position on seedling emergence and early growth of Chinese fir

以我国南方重要速生造林树种杉木为例,研究杉木种子所处凋落物位置对其幼苗出土及早期生长的影响.试验在温室大棚内进行,依据种子脱落后所处凋落物的可能位置,设置4个播种位置:种子位于1 cm土层下方(对照,无凋落物覆盖);种子位于凋落物表层(简称表层);种子位于凋落物和土壤之间(简称中间);种子位于1 cm土层下方且有凋落物覆盖(简称下方).凋落物覆盖厚度为400 g·m^(-2).结果表明:与对照相比,中间和下方处理对幼苗出苗率和存活率均有促进作用,表层处理对幼苗存活率具有抑制作用;与对照相比,中间和下方处理的幼苗茎、叶生物量和总生物量均有显著增加,表层处理则显著降低;表层处理的幼苗根生物量最大;表层处理的幼苗根生物量比及根冠比显著大于中间和下方处理;而表层处理的幼苗茎生物量比和叶生物量比显著低于中间和下方处理.

To study how relative positions of litter and seed influence the seedling emergence and early growth of plantation,Cunninghamia lanceolata(Lamb.)Hook(Taxodiaceae),the most important fast-growing afforestation species in southern China,was investigated.Four levels of seed position were established in the greenhouse,which included 1 cm beneath the soil surface without litter(control),on the litter surface without soil and seed contact(surface),on the soil surface and covered with litter(between),and 1 cm beneath the soil surface and covered with litter(bottom).Litters were applied at 400 g·m-2.The results showed that seedling emergence and survival rates of Chinese fir were much lower in the’surface’treatment than those in the’between’and’bottom’treatments.Compared with the control,stem biomass,leaf biomass and total biomass were significantly increased in’between’and’bottom’treatments,while significantly reduced in the’surface’treatment.While the largest root biomass was observed in’surface’treatment.Root mass ratio and root∶shoot ratio were significantly higher in’surface’than in’between’and’burial’treatments.Stem mass ratio and leaf mass ratio were significantly lower in’surface’treatment than in’between’and’bottom’treatments.Therefore,seedling emergence and growth were affected by seed position.And the optimum seed position for the emergence and growth of Chinese fir was beneath the litter rather than above it.