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Wang R.,Henan Forest Aviation Fire Station | Wang R.,South China Agricultural University | He Q.,South China Agricultural University | Ding X.-G.,Guangdong Forest Research Institute | And 4 more authors.
Beijing Linye Daxue Xuebao/Journal of Beijing Forestry University

Exponential nutrient delivery accelerating seedling growth could bring about a steady state of nutrition in the plant and improve nutrient uptake. An exponential fertilization trial was conducted with six nitrogen dose levels(applying a total of 0, 1000, 2000, 3000, 4000, 5000 mg/seedling in this experiment) of nitrogen to research the effects of different nitrogen levels on growth and photosynthetic physiology of Aquilaria malaccensis and Aquilaria sinensis seedlings. It was indicated that nitrogen fertilization could bring a significant impact on growth and photosynthetic physiology of seedlings. Ground diameter, height and biomass of seedlings increased with the increase of nitrogen supply up to 3000 mg/seedling, after then growth performance and biomass were unchanged. The total leaf area of A. malaccensis (1995.33 cm 2) and A. sinensis (1366.57 cm 2) fertilized by 3000 mg/seedling achieved maximum, and the lamina mass per unit area (LMA) of A. seedlings was high at mid-growth. The nitrogen exponential fertilizations played an important role in the adjustment of net photosynthetic rate, transpiration rate and light response curves of Aquilaria seedlings. Under the nitrogen fertilization level (3000 mg/seedling), the photosynthetic physiology characters of Aquilarias seedlings reached the maximums. Source

Wang R.,Beijing Forestry University | Wang R.,Guangdong Forest Research Institute | Li J.,South China Agricultural University | Zhang F.,Guangdong Forest Research Institute | And 2 more authors.
Shengtai Xuebao/ Acta Ecologica Sinica

Nitrogen is one of the most important limiting nutrients during tree growth. In this paper, the effects of nitrogen treatments with the exponential fertilization method, traditional fertilization method (mean fertilization) and non-fertilization on the total biomass and morphology parameters in roots of one-year-old Aquilaria malaccensis and Aquilaria sinensis seedlings were studied during a five-month period. The results suggested that N supply could significantly increase the root total biomass and root morphology parameter such as root length, root surface-area, root diameter, root volume and specific root length (P < 0. 0 5). The root total biomass and root morphology parameter of the two Aquilaria seedlings from the exponential fertilization treatment were higher than those showed from the mean fertilization treatment. The conclusion is that the plants of Aquilaria malaccensis and Aquilaria sinensis treated with exponential fertilization can reach the highest growth rate. The Lorentzian model as a multi-variable nonlinear model was firstly applied to the simulations using both base diameter and height, and performed the best fit to total root biomass in the two species with the highest correlation coefficients (R2, 0. 95-0.99) and smallest root mean squared deviations (RMSD,0.538-2.352) among all the examined models. The Paraboloid model accurately simulated base diameter, height, and performed the best fit to specific root length in the two species with the highest correlation coefficients (R 2, 0. 92-0.99) and smallest root mean squared deviations (RMSD,3. 218-6.692) among all the examined models. Source

Wei S.G.,Guilin University of Electronic Technology | Li L.,Guilin University of Electronic Technology | Chen Z.C.,Guilin University of Electronic Technology | Lian J.Y.,CAS South China Botanical Garden | And 3 more authors.

The species-area relationship is one of the most important topic in the study of species diversity, conservation biology and landscape ecology. The species-area relationship curves describe the increase of species number with increasing area, and have been modeled by various equations. In this paper, we used detailed data from six 1-ha subtropical forest communities to fit three species-area relationship models. The coefficient of determination and F ratio of ANOVA showed all the three models fitted well to the species-area relationship data in the subtropical communities, with the logarithm model performing better than the other two models. We also used the three species-abundance distributions, namely the lognormal, logcauchy and logseries model, to fit them to the species-abundance data of six communities. In this case, the logcauchy model had the better fit based on the coefficient of determination. Our research reveals that the rare species always exist in the six communities, corroborating the neutral theory of Hubbell. Furthermore, we explained why all species-abundance figures appeared to be left-side truncated. This was due to subtropical forests have high diversity, and their large species number includes many rare species. © 2014 Wei et al. Source

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