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Zeng W.,Central South University of forestry and Technology | Zeng W.,National Engineering Laboratory of Applied Technology for Forestry and Ecology in Southern China | Zhou B.,Central South University of forestry and Technology | Lei P.,Central South University of forestry and Technology | And 9 more authors.
Frontiers in Plant Science | Year: 2015

Understanding of belowground interactions among tree species and the fine root (≤2 mm in diameter) contribution of a species to forest ecosystem production are mostly restricted by experimental difficulties in the quantification of the species composition. The available approaches have various defects. By contrast, DNA-based methods can avoid these drawbacks. Quantitative real-time polymerase chain reaction (PCR) is an advanced molecular technology, but it is difficult to develop specific primer sets. The method of next-generation sequencing has several limitations, such as inaccurate sequencing of homopolymer regions, as well as being time-consuming, and requiring special knowledge for data analysis. This study evaluated the potential of the DNA-sequence-based method to identify tree species and to quantify the relative proportion of each species in mixed fine root samples. We discriminated the species by isolating DNA from individual fine roots and amplifying the plastid trnL(UAA; i.e., tRNA-Leu-UAA) intron using the PCR. To estimate relative proportions, we extracted DNA from fine root mixtures. After the plastid trnL(UAA) intron amplification and TA-cloning, we sequenced the positive clones from each mixture. Our results indicated that the plastid trnL(UAA) intron spacer successfully distinguished tree species of fine roots in subtropical forests. In addition, the DNA-sequence-based approach could reliably estimate the relative proportion of each species in mixed fine root samples. To our knowledge, this is the first time that the DNA-sequence-based method has been used to quantify tree species proportions in mixed fine root samples in Chinese subtropical forests. As the cost of DNA-sequencing declines and DNA-sequence-based methods improve, the molecular method will be more widely used to determine fine root species and abundance. © 2015 Zeng, Zhou, Lei, Zeng, Liu, Liu and Xiang.


Hu R.-B.,Central South University of forestry and Technology | Fang X.,Central South University of forestry and Technology | Fang X.,National Engineering Laboratory for Applied Forest Ecological Technology in Southern China | Fang X.,Huitong National Field Station for Scientific Observation and Research of Chinese Fir Plantation Ecosystem in Hunan Province | And 13 more authors.
Chinese Journal of Applied Ecology | Year: 2016

In order to investigate spatial variations in soil phosphorus (P) concentration and the influencing factors, one permanent plot of 1 hm2 was established and stand structure was surveyed in Choerospondias axillaries deciduous broadleaved forest in Dashanchong Forest Park in Changsha County, Hunan Province, China. Soil samples were collected with equidistant grid point sampling method and soil P concentration and its spatial variation were analyzed by using geostatistics and geographical information system (GIS) techniques. The results showed that the variations of total P and available P concentrations in humus layer and in the soil profile at depth of 0-10, 10-20 and 20-30 cm were moderate and the available P showed higher variability in a specific soil layer compared with total P. Concentrations of total P and available P in soil decreased, while the variations increased with the increase in soil depth. The total P and available P showed high spatial autocorrelation, primarily resulted from the structural factors. The spatial heterogeneity of available P was stronger than that of total P, and the spatial autocorrelation ranges of total P and available P varied from 92.80 to 168.90 m and from 79.43 to 106.20 m in different soil layers, respectively. At the same soil depth, fractal dimensions of total P were higher than that of available P, with more complex spatial pattern, while available P showed stronger spatial correlation with stronger spatial structure. In humus layer and soil depths of 0-10, 10-20 and 20-30 cm, the spatial variation pattern of total P and available P concentrations showed an apparent beltshaped and spot massive gradient change. The high value appeared at low elevation and valley position, and the low value appeared in the high elevation and ridge area. The total P and available P concentrations showed significantly negative correlation with elevation and litter, but the relationship with convexity, species, numbers and soil pH was not significant. The total P and available P exhibited significant positive correlations with soil organic carbon (SOC), total nitrogen concentration, indicating the leaching characteristics of soil P. Its spatial variability was affected by many interactive factors. © 2016, Science Press. All right reserved.


Xiang W.,Central South University of forestry and Technology | Xiang W.,Huitong National Field Station for Scientific Observation and Research of Chinese Fir Plantation Ecosystem in Hunan Province | Fan G.,Central South University of forestry and Technology | Fan G.,Huitong National Field Station for Scientific Observation and Research of Chinese Fir Plantation Ecosystem in Hunan Province | And 12 more authors.
Plant and Soil | Year: 2015

Background and aims: Belowground interactions can greatly modify fine root (≤2 mm in diameter) traits to increase soil resource acquisition for tree growth. We examined how mixed forests alter fine root traits compared to pure forests. Methods: A pseudo-experimental tree cluster design was used to select small-area plots of single and mixed species in a Pinus massoniana–Lithocarpus glaber (PM–LG) forest and a L. glaber–Cyclobalanopsis glauca (LG–CG) forest. In each plot, soil cores were sampled down to 30 cm at a 0.5 m interval between target and neighbouring trees. Fine roots in soil cores were then divided by species to determine biomass and morphological traits. Results: The mixed PM–LG plots exhibited significantly higher fine root biomass while the mixed LG–CG plots had no significant differences in fine root biomass compared to their respective pure plots. In pure plots, P. massoniana had higher fine root biomass and lower specific root length (SRL) and specific root area (SRA) than L. glaber, whereas fine root traits were similar for L. glaber and C. glauca. Compared with pure plots for a given species, fine root biomass in the entire soil profile decreased for P. massoniana but increased for L. glaber in mixed PM–LG plots. In mixed LG–CG plots, fine root biomass decreased for each species at all soil depths. Conclusions: Whether positive interactions of fine roots occur is dependent on tree species composition. Fine root biomass was greater in mixed forests where tree species showed contrasting growth strategies and root traits, such as PM-LG forests, thus suggesting positive interactions. © 2015 Springer International Publishing Switzerland

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