不同水分处理和密度配置对牛鞭草与狗牙根生长与种间竞争的影响

为合理利用三峡库区消落带优良草本植物进行退化植被恢复,并探索恢复过程中草本植物的最佳混植比例,选取三峡库区消落带适生先锋草本植物牛鞭草(Hemarthria compressa)(H)和狗牙根(Cynodon dactylon)(C)为研究材料,于2016年4月29日在盆栽控制条件下设置3种不同水分条件(对照组——CK组、浅淹组——SF组、全淹组——TF组)、7种配置比例,每盆牛鞭草与狗牙根株数分别按2株进行递增与递减,具体的配比分别为H0C12,H2C10,H4C8,H6C6,H8C4,H10C2、H12C0,比较研究混植条件下牛鞭草与狗牙根在水淹环境中的生长及二者的竞争作用。研究发现:(1)无论在单植还是二者混植条件下,水分胁迫均显著降低狗牙根与牛鞭草生物量,且牛鞭草对水淹胁迫的响应更敏感;(2)狗牙根和牛鞭草的生长均具有明显的密度制约效应,但狗牙根的反应更为强烈;(3)不同水分与密度条件下,混植体系总相对生物量均大于1。在CK组,狗牙根与牛鞭草表现出竞争关系;在SF组和TF组,二者之间的竞争作用减小,表现出一定的促进作用。综合分析本试验不同水分与密度条件下牛鞭草与狗牙根的总生物量、根冠比、竞争系数(相对总生物量),发现常规供水处理下牛鞭草和狗牙根的最佳配置比例为H2C10,而浅水淹和深水淹处理下最佳配置比例为H8C4。研究结果可以为三峡库区消落带不同海拔位草本植被的恢复及管理提供依据,也为生态类型相同或相似地区人工恢复草本植被提供理论参考。

Effects of different water conditions and plant density on the growth and interspecific competition of Hemarthria compressa and Cynodon dactylon

To restore the degraded grass vegetation and reveal the best ratio of grass species for artificial restoration of the riparian zone of the Three Gorges Reservoir area, the local dominant species, Hemarthria compressa (H) and Cynodon dactylon (C) were used to investigate the growth and intraspecific and interspecific competition under different water conditions. On April 29, 2016, a pot experiment was conducted using a replacement series design in which H. compressa and C. dactylon were planted at seven ratios (H0C12, H2C10, H4C8, H6C6, H8C4, H10C2, and H12C0) under three water treatments, including normal growth water condition (CK), flooding at 10 cm above the soil surface (SF) and flooding at 2 m above the soil surface (TF). Results showed that:(1) Regardless of the planting being a monoculture or a combination of the two species, biomass production of both species decreased under water stress. H. compressa was more sensitive to water stress than C. dactylon; (2) There was a density-dependent effect on the growth of both species and this effect was stronger on C. dactylon; (3) Under all three water treatments, the relative yield total (RYT) was greater than 1 when both species were planted. Under CK, the two species showed a competitive relationship, whereas under SF and TF, they were facilitated by each other. Taking maximizing biomass production, the root:shoot ratio, and the competitive ability of the species into consideration, we suggest that under CK, the best ratio for planting of H. compressa and C. dactylon is 2:10, whereas under SF and TF, the best ratio is 8:4. These results provide a baseline reference for vegetation restoration and reconstruction in the riparian zone of the Three Gorges Reservoir area, and provide a theoretical reference for the establishment of artificial grass vegetation in similar areas.