匍匐茎草本蛇莓克隆构型对土壤养分的可塑性反应

Plasticity of clonal architecture in response to soil nutrients in the stoloniferous herb Duchesnea indica Focke

克隆植物构型的可塑性可使它在养分斑块性分布的环境中 ,相应地调整对土壤养分的获取对策 ,因而可能具有重要的生态学意义。在一项田间实验中 ,匍匐茎草本蛇莓 (Duchesnea indica Focke)经历了不同土壤养分水平 (高、中、低和对照 )处理 ,以研究土壤养分对蛇莓克隆构型的影响。结果表明 :随着土壤养分水平的增加 ,间隔子的长度和分枝角度均逐渐降低 ,而分枝强度和分株密度增加。在不同养分水平生境中 ,蛇莓克隆构型相关特征的可塑性变化可用动态 Logistic模型进行模拟和预测 ,拟合效果较好。结合植物对环境异质性的利用对策 。

Architectural plasticity of clonal plants may modify their ways of utilization of soil nutrients in their habitats of resource heterogeneity, and therefore be ecologically important. The plasticity of clonal architecture, in terms of space length, branch intensity and branch angle, in response to soil nutrients in the stoloniferous herb, Mock-strawberry (Duchesnea indica Focke), was investigated using the method of experimental ecology. The experimental plant materials were collected from Chinese subtropics (31° 34′ N; 104° 42′ E). The experiment was conducted from Sept. 30, 1999 to June 30, 2000. The soil had 1.02%～1.08% organic matter, 0.093% N, 0.047% P, 1.72% K and pH 7.2. The nutrient experiment was carried out with high, medium, low levels of N, P, K. The high fertilizer level was equivalent to N 150kg hm -2a -1, P 75kg hm -2a -1 and K 150kg hm -2a -1. The medium and low fertilizer levels were 2/3 and 1/3 of the high level, respectively. No fertilizer was supplied under control nutrient level. The experimental plot was 20 m 2, with density of 1 genet·m -2. There were five replicates in each treatment. The spacer length and branch angle decreased with increase of soil nutrients. The average spacer length was 2.8cm, 3.6cm, 6.3cm and 8.5cm under the high, medium, low and control nutrient level, respectively. The average branch angle was 29.1°, 40.7°, 55.1° and 71.3° under the high, medium, low and control nutrient level, respectively. The ramet density and branch intensity increased with increase of soil nutrients. The branch intensity was 11.7, 9.91, 7.90 and 6.12 stolons·genet -1 under the high, medium low and control nutrient level, respectively. The ramet density was 102.7, 85.5, 59.4 and 35.1 under the high, medium, low and control nutrient level, respectively. The model of clonal architecture in relation to different levels of soil nutrients was created using Marquardt in Statistical Analysis System and estimating the parameter of the Logistic model:N spacer=53.5521+exp[1.1152+0.3882f-0.3351(f-3.6686)hazard(f-3.6686)](1) N density=168.80541+exp[1.3806-0.2056f-0.2198(f-10.1215)hazard(f-10.1215)](2) N angle=291.04441+exp[0.0406+0.6329f-0.54(f-2.2843)hazard(f-2.2843)](3) N\-\{\%intensity\%\}=40.561+\%exp\%\[2.44-0.57f+0.5(f-1.65)hazard(f-1.65)\] (4) Simulation of clonal architecture to the spacer length, ramet density, branch angle and branch intensity under the different soil nutrients was conducted according to the equations (1), (2), (3) and (4). The fitting analysis shows a highly significant level. The Logistic Model had good simulation effect on the clonal architecture. We focused on the plasticity changes of clonal architecture of Mock-strawberry in terms of space length, branching intensity, branching angle and ramet density under the different levels of soil nutrients. The changes were expressed, elucidated and simulated using Logistic Model. Previous studies of clonal plant ecology suggest that branch angle of clonal plants is hardly plastic and hardly contributes to selective placement of ramets in the habitats of resource heterogeneity. Therefore little attention was paid to the importance of plasticity of branch angle in response to resource heterogeneity. In this study, however, branch angle of the Mock-strawberry from the Chinese subtropics did change significantly in response to variation in soil nutrients. It decreased with the increase of soil nutrients. This result suggests that the branch angle of clonal plants might have a contribution to the clonal architecture in Mock-strawberry clone growing the heterogeneous environment and plasticity of branch angle should receive attention in future researches. Soil nutrients in a habitat are often distributed heterogeneously. When a plant extends from one patch to another by clonal growth, the change in clonal architecture may have significance of ecological adaptability. The resources and conditions in a patch affect not only the ramets in the patch but also the connected ramets in differen