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三峡水库消落带草本植物的消浪减蚀作用机理
Alternative TitleThe Role of Grasses in Wave attenuation and Erosion Control in the Riparian Zone of Three Gorges Reser
Language中文
钟荣华
Thesis Advisor贺秀斌
2015
Degree Grantor中国科学院大学
Place of Conferral北京
Degree Name博士
Degree Discipline土壤学
Keyword草本植物 根系粘聚力 消浪减蚀 消落带 三峡水库
Abstract三峡水库消落带对库区生态环境健康和水库水质安全起着重要作用。严重的库岸侵蚀是三峡水库消落带的主要环境安全问题之一,而植被恢复是治理消落带的关键措施。研究消落带植物的消浪功能和水土保持效应,对科学合理地制定三峡水库消落带植被恢复和水土保持策略具有重要的现实意义和科学价值。因此,本论文通过野外现场调查、水槽试验、土壤理化特性、根系分布特征与抗拉力学性质等分析,探讨消落带草本植物的消浪减蚀作用机理。论文主要结论如下: (1)对研究区三种人工恢复草-牛鞭草(Hemarthria altissima (Poir.) Stapf et C. E.)、扁穗牛鞭草(Hemarthria compressa (L. f.) R. Br.)和双穗雀稗(Paspalum paspaloides (Michx.) Scribn.)和自然恢复草-狗牙根(Cynodon dactylon (L.) Pers.)的根系进行了采样和提取,并用WinRHIZO根系分析系统进行分析,结果显示三种自然恢复草本70%以上的根系都分布在表层0―5 cm土层中,而狗牙根表层根系(0―5 cm)则占到60%以上。除根径外,三种人工恢复草的各根系指标均要高于狗牙根。四种草本的根直径均小于1 mm,平均根面积比为0.21%,不同土层根长密度介于0.24~20.89 cm/cm3,根表面积密度介于0.22~13.44 cm2/cm3,根体积密度介于0~0.03 cm3/cm3,根尖密度介于0~120 个/cm3。根长密度和根面积比均沿土壤深度程幂函数递减分布;而根直径、根表面积密度、根体积密度和根尖密度均沿土壤深度呈指数递减分布。 (2)以裸地为对照,对四种草地的土壤理化性质进行了测定分析,结果显示植物及其根系的存在对土壤容重、土壤体积磁化率和抗剪强度都有重要影响。其中裸地的土壤容重要显著高于四种草地,而表层土壤体积磁化率则要弱于草地。直剪试验结果显示牛鞭草和狗牙根均可以显著增强土壤抗剪强度,其中牛鞭草地0―10 cm和10―20 cm层土壤粘聚力(分别比裸地增加319.81%和46.89%,而狗牙根草地对比裸地土壤粘聚力的增加幅度分别为17.69%(0―10 cm)和43.13%(10―20 cm)。植被及其根系的存在对土壤养分的剖面分布也有重要影响,裸地的SOC和总N含量要显著低于草地。 (3)采用自组装根系抗拉仪测定了四种消落带草本根系抗拉力学性质,结果显示四种草本单根平均抗拉强度次序为狗牙根(62.26 MPa)>扁穗牛鞭草(51.29 MPa)>牛鞭草(50.66 Mpa)>双穗雀稗(48.81 MPa)。4种草本根系抗拉力随直径增大呈幂函数增大,抗拉强度则随直径增大而呈幂函数减小。应用Wu氏正交模型估算了四种草本根系对土壤粘聚力的增强作用,结果显示四种草本根系均可以显著地增加土壤粘聚力,扁穗牛鞭草、牛鞭草、双穗雀稗、狗牙根平均增加黏聚力分别为4.90、4.69、4.42和3.12 kPa。尽管狗牙根的根系抗拉强度要高于其他三种人工恢复植物,然而由于其根系密度小,因此对土壤黏聚力的增强效应反而要低于三种人工恢复草本。 (4)采用水槽造波试验研究了狗牙根和牛鞭草2种草本植物的消浪减蚀效应,狗牙根和牛鞭草的平均消浪系数分别为0.37、0.30,平均侵蚀模数分别为17.63、57.30 g/(m2·min),而裸地平均侵蚀模数高达799.40 g/(m2·min)。2种草本的减蚀效应均在89%以上,最高可达98.59%,其中牛鞭草根系的固土贡献率高达91.4%~92.6%,而狗牙根根系的固土贡献较牛鞭草小,为71.2%~76.2%。可见,消落带植物是通过其地上部分消浪和地下根系固结土壤来共同发挥减蚀功能。 综上所述,三种人工恢复草本(牛鞭草、扁穗牛鞭草和双穗雀稗)的根系要比自然恢复草本-狗牙根发达,对土壤黏聚力的增强作用也要高于狗牙根,但狗牙根的地上部分消浪效应要强于牛鞭草,因此综合减蚀效应狗牙根与牛鞭草相当。可见,植物在消落带除了发挥传统水土保持功能,其还可以通过地上部分阻挡和削弱库水和波浪对岸坡土体冲刷。消落带植物正是通过植物地上部分的阻挡水流、消能消浪和地下根系的固土作用共同发挥保土护岸功能。为此,在消落带的植被恢复和水土保持工程中,建议兼顾经济效应,选择根系发达,根系抗拉性能好,同时地上部分消浪功能强的植物,如本研究中的狗牙根和牛鞭草,更能发挥强大的保土护岸功能。
Other AbstractSoil erosion and bank degradation is a major post–dam concern regarding the riparian zone of Three Gorges Reservoir. The development and succession of vegetation are the main countermeasures, especially to enhance bank stability and mitigate soil erosion. Determing the role of plants in wave attenuation and erosion control affords an important practical and scientific basis for implementing soil conservation practices and riparian revegetation in the riparian zone of TGR. In the present study, the wave attenuation and erosion control capabilities of several grass species in WLFZ were preliminarily revealed via the flume experiments, the root features were measured using the WinRHIZO image analysis system, and the soil reinforcement due to roots were estimated using the Wu perpendicular model. The main conclusions in this dissertation are as follows: (1) The root distribution characteristics of four grasslands (three artificial restoration herbs, i.e. Hemarthria altissima (Poir.) Stapf et C. E., Hemarthria compressa (L. f.) R. Br. and Paspalum paspaloides (Michx.) Scribn.) and one natural restoration grass (Cynodon dactylon (L.) Pers.) were investigated in the riparian zone of TG. Root length density and root area ratio were measured using the WinRHIZO image analysis system. The results showed that roots mainly distributing in 0―10 cm soil depth, root length density (RLD), root diameter (RD) (except for C. dactylon), root surface area density (RSAD), root bulk density (RBD) and root tips density (RTD) were decreased exponentially with soil depth. RD for all species were less than 1 mm. RLD values of the studied plants ranged from 0.24 to 20.89 cm/cm3, RSAD were ranged from 0.22~13.44 cm2/cm3, RTD were ranged from 0~0.03 cm3/cm3, RTD were between 0~120 per cm3, and these values are significantly higher for the topsoil (0–10 cm) compared to the subsoil (<10 cm). Root area ratio estimates showed that on average plant roots occupy 0.21% of the area under the crown of the selected species. Excluding the relationships between RD and other root indicators of P. paspaeoides, relationships between RLD and RBD, RD and other roots features of natural recovery grasses were not significantly correlation, other roots features were significantly correlated. Generally, root features of three artificial restoration herbs for the soil profiles (0―30 cm) were considerably higher than natural recovery grasses. From the perspective of roots, herbs artificial restoration herbs have good adaptability when under the similarity long submerged stress conditions, which provides a more fully evidence for artificial recovery vegetation in the riparian zone of TGR. (2) Soil properties of these mentioned grass species with bare area as the control also were studiedR. The results showed no significant differences were found among the studied grasslands for soil bulk density, soil particle composition and soil volume magnetic susceptibility. However, the bulk density and soil shear strength in bare land were significantly higher compared to grasslands. Meanwhile, the plant and its root systems have a significant impact on the distribution of soil nutrient in soil profiles. Soil organic carbon (SOC) and total N contents in bare land was significantly lower than the grass land. Total nutrients in H.compressa land and natural recovery land were higher than other grasslands. The RLD and RAR were significantly correlated with SOC and total N contents for four studied grasslands. (3) Root tensile strength was performed using a manual dynamometer. Root cohesion values were calculated using a simple perpendicular model. Results showed that the measured mean tensile force for C. dactylon, H. altissima, H. compressa and P. paspaloides were 5.86, 5.55 5.50 and 4.14 N, respectively. Also, the mean root tensile strength was 62.26 MPa for C. dactylon followed by H. compressa (51.49 MPa), H. altissima (50.66 MPa) and P. paspaloides (48.81 MPa).
Document Type学位论文
Identifierhttp://ir.imde.ac.cn/handle/131551/14182
Collection山地表生过程与生态调控重点实验室
Affiliation中国科学院成都山地灾害与环境研究所
Recommended Citation
GB/T 7714
钟荣华. 三峡水库消落带草本植物的消浪减蚀作用机理[D]. 北京. 中国科学院大学,2015.
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