|
Bamboo forest is an important component of China forest resources, and Zhejiang is one of the richest bamboo resources provinces in China. Phyllostachys edulis、Phyllostachys praecox and Bambusa oldhami are important bamboo species used for both economical and ecological purpose in Zhejiang province. With the increasing of bamboo forest planting area, management technology study on bamboo are drawing more and more attention, especially for how to exert slope protection and keep soil of the three bamboo timber while improving economic efficiency in the management process. In this thesis, the underground root system structure and biomechanical characteristics of bamboo was studied, the results are showed as follows:(1) No matter basal root or rhizome root, both of them were "V"-shaped distribution in soil for the studied bamboo species, with 0～40cm soil layer being the main distribution and activities layer, four indicators for Bambusa oldhami basal root:dry weight, length, volume and surface area accounted for 88.31%～93.81%;for Phyllostachys edulis: basal root accounted for 83.45%～85.38%, rhizome root accounted for 82.66%～83.90%;Phyllostachys praecox: basal root accounted for 100%, rhizome root accounted for 85.56%～81.73%.(2) As for diameter class, root with diameter <1mm accounted for the largest in terms of the length. Among them, Bambusa oldhami:<1mm accounted for 78.47%; Phyllostachys edulis:basal root accounted for 70.45%, rhizome root accounted for 75.70%; Phyllostachys praecox:basal root accounted for 80.46%, rhizome root accounted for 83.62%.In terms of the volume,>2mm accounted for the largest, Bambusa oldhami: basal root accounted for 62.40%; Phyllostachys edulis: basal root accounted for 78.73%, rhizome root accounted for 79.23%; Phyllostachys praecox:basal root accounted for 43.61%, but for rhizome root, root with diameter between 1mm-2mm took the the advantage, accounting for 50.78%.(3) Whether saturated moisture or 12% moisture content, the tensile strength of root among diameter classes all showed difference, with the root with diameter <1mm always was the largest (except for Phyllostachys praecox rhizome root under 12% moisture content ); the most tension that root could bear increased as the root diameter increasing. Moisture content could affected root tensile strength, but the impact was different on different bamboos and diameter classes,among them,under 12% content, tensile strength of <1mm was lagerest for Phyllostachys praecox and Bambusa oldhami, respectively was 61.34MPa and 45.63MPa; but for Phyllostachys edulis, <1mm was the largest under saturated moisture ,was 48.02MPa;(4) Both Phyllostachys edulis and Phyllostachys praecox,have a certain variation on tensile strength of different rhizome with different age, grown rhizome > old rhizome > young rhizome. For grown rhizome of Phyllostachys edulis,it is the largest(62.08Mpa), while the young rhizome of Phyllostachys praecox is the smallest(18.86Mpa). However, Phyllostachys edulis and Phyllostachys praecox was different in the disparity level, the disparity among different age for Phyllostachys edulis all was extremely significant, but for Phyllostachys praecox, only the disparity between the old and young rhizome was extremely significant,the disparity between old and grown rhizom was not significant.(5)For Phyllostachys edulis rhizome elastic modulus: the young was the largest, the grown was the smallest,the old was in medium.And the difference between rhizome age was extremely significant. For Phyllostachys praecox elastic modulus: the old was the largest, the young was in medium, and the grown was the smallest. And the difference between the old and the young was not significant, but that between the young and the grown was extremely significant. Among elastic modulus, the old of Phyllostachys praecoxwas was the largest(22452.83Mpa), the young of Phyllostachys edulis was the smallest(9266.67Mpa).That was to say, Phyllostachys praecox rhizome rigidity was bigger than Phyllostachys edulis rhizome.As for one bamboo species,the young and the old rhizome rigidity was bigger than the grown.(6) Shearing strength of soil increased with deepening of soil layers, and shearing strength of root systems not directly related to soil layers, but positively correlated with the dry weight of root in soil, and the correlation was different for different bamboo species.
|