Effects of fertilization on Alnus formosana fine root morphological characteristics, biomass and issue content of C, N under A. formosana-Hemarthria compressa compound mode

Abstract

Aims Our objectives were to: 1) examine fine root biomass, morphological characteristics and content of C and N of Alnus formosana in an A. formosana-Hemarthria compressa composite model in Danling, Sichuan Province, China, 2) examine the effects of fertilization on each order of fine roots, and 3) analyze the relationship between soil nutrients and fine root biomass, architecture and content of C and N. Methods In September 2010, we established two subdistricts, eradicated weeds and planted H. compressa. We fertilized one subdistrict with N-P-K fertilizer in April, June, August and October and did not fertilize the other subdistrict. We excavated soil blocks of 20 cm × 20 cm × 10 cm (height) to sample intact fine root branches of at least the first branch orders. We dissected the intact root branches by orders and measured the diameter, specific root length, biomass, and C and N content of each order. Important findings Fertilization reduced fine-root average diameter in soil surface and increased that in soil subsurface. In fine-root orders 1–5, specific root length increased as root order decreased. Fertilization significantly increased specific root length in fine-root orders 1–3 in soil surface and subsurface (p 0.05). Soil surface total N content of fine roots of 1–5 苗宇等: 施肥对台湾桤木-扁穗牛鞭草复合模式下桤木细根形态特征、生物量及组织碳氮含量的影响 675 doi: 10.3724/SP.J.1258.2013.00070 orders was higher than that in subsurface. Fertilization significantly (p 0.05).