Welcome to visit Scientia Silvae Sinicae，Today is

Scientia Silvae Sinicae ›› 2015, Vol. 51 ›› Issue (1): 119-126.doi: 10.11707/j.1001-7488.20150114

Previous Articles     Next Articles

Morphological and Anatomical Traits of Poplar Fine Roots in Successive Rotation Plantations

Xu Tan1, Wang Huatian1,2, Zhu Wanrui1, Wang Yanping1,2, Li Chuanrong1,2, Jiang Yuezhong3   

  1. 1. Silviculture Key Lab of Shandong Province Forestry College of Shandong Agricultural University Tai'an 271018;
    2. Taishan Forest Ecosystem Research Station of State Forestry Administration Tai'an 271018;
    3. Shandong Academy of Forestry Jinan 250014
  • Received:2013-09-27 Revised:2014-12-10 Online:2015-01-25 Published:2015-01-23

PDF (PC)

900

Abstract:

[Objective]The productivity of poplar plantation with successive rotations depleted seriously. Based on morphological and anatomical properties of the fine roots, the inter-rotation difference of fine root growth and its relation to the depletion of plantation productivity were studied to reveal mechanisms of the productivity depletion of plantation with successive rotations. [Method]Sample plots were set up in plantations respectively at the first and second rotations. Using the improved complete-root sampling method, fine roots (< 2 mm) of sample trees were collected and grouped into 1-5 classes according to orders of the roots. WINRHIZO root system analyzer (Canada) and corresponding software were used to determine the morphological properties: length and diameter. Furthermore, permanent paraffin sections of the 1-5 classes of fine roots were prepared to observe the anatomical properties: cross section diameter, cortex thickness and xylem diameter. Finally, several important parameters related to fine root morphology, i.e. specific root length (SRL), root tissue density (RTD), root length density (RLD) and percentage of xylem to cross section area were calculated. Least-significant difference (LSD) multiple comparisons were used to analyze differences of fine root morphological properties among the 1-5 root classes, and one-way ANOVA was used for the analysis of difference of the same class of fine root morphology between first and second rotations of poplar plantation (P<0.05). [Result]There were significant differences of biomass allocation among the fine root classes, and biomass allocation appeared to decrease with increase of root orders. The biomass of fine roots in the second rotation plantation was significantly higher than that in the first rotation, especially for 1,2 root classes (P <0.05). The mean root length was also significantly different among the root classes. The mean root length of 1,2 root classes was decreased and that of 3-5 root classes was increased in the second rotation plantation. Although root diameter showed no significant differences among root classes, it was still larger in the second rotation plantation. Also, the surface area, specific root length and root length density of 1,2 order roots were significantly higher than those of 3,4 order roots (P <0.05), but the specific root length showed no significant difference among orders in second rotation plantation. The surface area and root length density of 1,2 root classes displayed a significant increase in the second rotation, but specific root length was significantly decreased (P <0.05). The anatomical properties showed that the cross section diameter of all fine roots increased with root classes and the same trend was found with the area ratio of stele (or vascular cylinder) to cross section. The anatomical properties of the 1,2 root classes was characterized as primary structure in general, while phellem layer was formed from the 3rd root class and cortex layer started to fall off.[Conclusion]There were significant differences in morphology ad functions among the 1-5 classes of fine roots. Fine roots of the 1,2 root classes were of primary structure, indicating that they serve as absorbing roots, while fine roots of the 3-5 root classes formed the secondary phellem layer, indicating that they act as transporting roots for water and nutrients. Successive rotations led to significant changes of fine root morphology and significant increases of fine roots biomass, indicating that the biomass allocation to underground part was increased in poplar plantation with successive rotations. This conclusion was consistent with the theory of optimal allocation of photosynthetic products under nutrient deficiency conditions. With fine roots mortality and turnover, the allocation pattern of fine root biomass of poplar plantation with successive rotations would have a negative effect on aboveground productivity.

Key words: poplar plantation, seccessive rotation, fine root biomass, specific root length, anatomical traits, productivity decline

CLC Number: