不同针叶树混交对水曲柳吸收根和运输根形态与生物量垂直分布的影响

Effects of Mixed Coniferous Tree Plantation on the Morphology of Absorption and Transportation Roots and Vertical Distribution of Biomass in Fraxinus mandshurica

为研究树种之间根系的相互作用,以黑龙江省东北林业大学帽儿山地区的水曲柳(Fraxinus mandshurica)纯林和水曲柳与兴安落叶松(Larix gmelinii)、红松(Pinus koraiensis)、红皮云杉(Picea koraiensis)的混交林为研究对象,采用根钻法,研究了不同针叶树混交对水曲柳吸收根和运输根形态与生物量的垂直分布特征的影响。结果表明:在土壤表层(0<土壤深度(d)≤10 cm)和亚表层(10 cm<d≤20 cm),水曲柳红松混交林、水曲柳兴安落叶松混交林内,水曲柳吸收根生物量显著高于水曲柳纯林。4种林型内,水曲柳吸收根和运输根生物量均随土壤深度加深呈现下降的趋势,其中,45.79%~53.76%的吸收根和39.63%~49.39%的运输根位于土壤表层。在土壤表层,水曲柳云杉混交的运输根比根长显著降低,根平均直径显著增加。在土壤亚表层,水曲柳云杉混交的吸收根和运输根组织密度及吸收根平均直径显著低于纯林,而吸收根比根长显著高于纯林。水曲柳吸收根和运输根平均直径随土壤深度增加整体呈现增加的趋势,且在运输根表现更加明显。吸收根生物量和比根长均与土壤全氮质量分数存在显著正相关。因此,水曲柳与红松、落叶松混交在一定程度上提高了目的树种水曲柳的吸收根生物量,增强了水曲柳对土壤资源的获取能力。

To investigate the interaction among tree species’roots,pure stands of Fraxinus mandshurica and mixed stands of F.mandshurica with Larix gmelinii,Pinus koraiensis,and P.koraiensis in the Ma’ershan region of Northeast Forestry University in Heilongjiang Province were selected as study subjects.Using the root drill method,the influence of different mixed coniferous tree plantations on the morphology of absorption and transportation roots and vertical distribution of biomass in F.mandshurica was studied.The results showed that in the topsoil layer(0<d≤10 cm)and subsoil layer(10 cm<d≤20 cm),the biomass of absorption roots in F.mandshurica-P.koraiensis mixed stands and F.mandshurica-L.gmelinii mixed stands was significantly higher than that in pure F.mandshurica stands.Across all four forest types,the biomass of absorption and transportation roots in F.mandshurica decreased with increasing soil depth,with 45.79%to 53.76%of absorption roots and 39.63%to 49.39%of transportation roots located in the topsoil layer.In the topsoil layer,the transportation roots specific root length significantly decreased,and the average diameter increased in F.mandshurica-P.koraiensis mixed stands.In the subsoil layer,the tissue density of absorption and transportation roots and average diameter of absorption root in F.mandshurica-P.koraiensis mixed stands were significantly lower than in pure stands,while the specific root length of absorptive roots was significantly higher.The average diameter of absorption and transportation roots of F.mandshurica increased with soil depth,with transportation roots showing a more prominent increase.The biomass and specific root length of absorption roots were significantly positively correlated with soil total nitrogen content.Consequently,the mixed planting of F.mandshurica with P.koraiensis and L.gmelinii to some extent increased the absorption root biomass of the target tree species F.mandshurica,enhancing its capability to acquire soil resources.