三倍体毛白杨—黑麦草复合模式细根和草根分布与生长特征

Study on the distribution and growth characteristics of the fine root of Triploidpopulus tomentosa and root of Lolium multiflorum under compound pattern in both cultivating land and forest

对退耕还林地三倍体毛白杨-黑麦草复合模式细根和草根分布与生长特征进行的研究结果表明,三倍体毛白杨直径 0～1和1～2 mm细根生物量在垂直分布上存在差异.直径0～1 mm细根在上层(0～20 cm)、中层(20～40 cm)和下层(40 cm以下)生物量分别为0.240 6, 0.325 0和0.241 0 t/hm2;而直径 1～2 mm细根在整个年生长过程中,其上、中和下层生物量分别为0.150 0, 0.125 0和0.027 0 t/hm2,说明直径 0～1 mm细根对根系生物量积累的贡献高于 1～2 mm.黑麦草草根生物量在垂直方向上,0～20 cm层生物量高达0.986 0 t/hm2,20 cm以下层生物量仅有0.117 0 t/hm2,呈现典型的'T'型分布规律.三倍体毛白杨直径 0～1和1～2 mm细根、细根总生物量和黑麦草草根在一个年生长周期均呈单峰型特征.树根和草根0～20 cm层生长在时间动态规律上同步增大或同步减小,但0～20 cm层草根生物量占上层总生物量的68.68%,高于细根生物量;20 cm以下层则细根生物量占下层总生物量的87.68%,高于草根生物量.因此,三倍体毛白杨幼林与黑麦草复合生态系统地下部分空间生物量积累的种间利用关系表现互利优势,适宜性强,在四川盆地西缘退耕还林工程中是较为适宜的推广模式.

This paper discusses the distribution and growth characteristics of fine roots in T. tomentosa and the root of L. multiflorum in both cultivated land and forest. The results from the study showed that there was a difference in the vertical distribution between fine roots with a diameter of 0- 1 mm compared to fine roots with a diameter from 1-2 mm. Over the whole life the biomass of the middle layer,lower layer and upper layers of the fine root（diameter 0-1 mm）were 0. 325 0, 0. 241 0 and 0. 240 6 t/hm^2, respectively, and that of upper lay- er, middle layer and lower layers of the fine root（diameter 1--2 mm）were 0. 150 0, 0. 125 0 and 0. 027 0 t/hm^2, respectively. The annual average biomass of the total fine root （diameter 0-2 mm）of middle layer, upper layer and lower layers were 0. 449 0, 0. 391 0 and 0. 268 0 t/hm^2, respectively. The roots of L. multiflorurn in the vertical direction displayed a ‘T＇ distribution and the biomass of upper layer and lower layers were 0. 986 0 and 0. 117 0 t/hm^2, respectively. During one growth period of T. tomentosa, the biomass, both of fine root and grass root, showed a single-apex line which peaked in summer. There was a synchronous change between fine root and grass root of upper layer, but the grass root accounted for 68.68% of the total biomass in upper layer and the fine root occupied 87.68% of the total biomass of the lower layer. In summary, when T. tomentosa in the young forest had been collocated with L. multiflorum, the compe tition on biomass accumulating underground was not fierce and inter-grown. So in a certain range of the west edge of Sichuan basin, it could be a comparatively suitable popularization model.