Effects of soil temperature on growth and biomass allocation in four boreal tree species

Trembling aspen (Populus tremuloides Michx.), black spruce (Picea mariana (Mill.) B.S.P.), white spruce (Picea glauca (Moench) Voss), and jack pine (Pinus banksiana Lamb.) seedlings were subject to seven soil temperature treatments 5,10, 15,20,25,30 and 35°C. At the beginning and end of the experiment, the height and diameter of all seedlings were measured. Ten seedlings from each treatment combination were harvested at the end of the experiment for the determination of biomass allocation. It was found that soil temperature, species and interaction of soil temperature and species had significant effects on biomass and relative growth rate (RGR) of diameter. The relationship between each parameter and soil temperature was modeled using a 3rd order polynomial function. The model showed that the optimum soil temperatures were 19.4°C, 17.3°C, 15.3°C and 21.8°C, respectively, for aspen, black spruce, white spruce and jack pine. The biomass variables showed nonlinear responses to changes in soil temperatures between 5°C and 30°C in all tree species. All the aspen seedlings, about 40 percent of jack pine, 20percent of white spruce and black spruce seedlings survived the 35°C treatment during the experiment. Among the species, aspen had the largest response in total biomass and biomass of different components to soil temperatures. The maximum total biomass for aspen was about 7 times the minimum value, the corresponding values for black spruce, jack pine and white spruce were 2.2, 2.4 and 2.3 times, respectively. The total biomass and biomass of different organs at soil temperature 5°C were smaller than those at temperature 30°C for aspen, black spruce and jack pine. The results were reversed for white spruce. The total biomass at 5°C was 14.3 percent of the value at the optimum soil temperature for aspen, the corresponding values for black spruce, jack pine and white spruce were 45 percent, 42 percent and 42 percent, respectively. Soil temperature did not significantly affect leaf to root ratio, shoot to root ratio, shoot mass to total mass ratio (SMR), leaf mass to total mass ratio (LMR), or stem mass to total mass ratio (SMR). But there were significant differences between species in all the above ratios and different species responded differently to soil temperature treatments. The relative growth rate (RGR) also varied with species. Soil temperature did not affect RGR in jack pine and white spruce. The RGR of black spruce was sensitive to soil temperatures over the whole range while RGR of aspen was only sensitive to soil temperature below 15°C

Novel models for fatigue life prediction under wideband random loads based on machine learning

Machine learning as a data-driven solution has been widely applied in the field of fatigue lifetime prediction. In this paper, three models for wideband fatigue life prediction are built based on three machine learning models, i.e. support vector machine (SVM), Gaussian process regression (GPR) and artificial neural network (ANN). The generalization ability of the models is enhanced by employing numerous power spectra samples with different bandwidth parameters and a variety of material properties related to fatigue life. Sufficient Monte Carlo numerical simulations demonstrate that the newly developed machine learning models are superior to the traditional frequency-domain models in terms of life prediction accuracy and the ANN model has the best overall performance among the three developed machine learning models

Variations in Litterfall Dynamics, C:N:P Stoichiometry and Associated Nutrient Return in Pure and Mixed Stands of Camphor Tree and Masson Pine Forests

Litterfall, directly and indirectly, affects the soil physicochemical properties, microbial activity, and diversity of soil fauna and flora by adding organic matter and nutrients to the soil. This study explores litterfall dynamics such as litterfall production, litter decomposition rate, and associated nutrient return in three forest types, that is, camphor tree forest (CTF), Masson pine forest (MPF), and camphor tree and Masson pine mixed forest (CMF), in subtropical China. Results showed that CMF had the highest mean annual litterfall production (4.30 ± 0.22 t ha−1), which was significantly higher than that of MPF (3.41 ± 0.25 t ha−1) and CTF (3.26 ± 0.17 t ha−1). Leaf represented the major fraction of litterfall, constituting over 71% of the total litterfall mass in the three forest types. The contribution of branch litter was 16.3, 8.9, and 16.9%, and miscellaneous litter was 12.6, 18.9, and 11.1% in CTF, MPF, and CMF, respectively. The concentration of macronutrients ranked as N > Ca > K > Mg > P in all litter fractions. The total annual macronutrient return to the soil from the litterfall was in order as CTF (74.2 kg ha−1‧yr−1) > CMF (70.7 kg ha−1‧yr−1) > MPF (33.6 kg ha−1‧yr−1). The decomposition rate was higher in leaf litter than in branch litter throughout the three forests. Among the forest types, the leaf and branch decomposition rates were in a pattern: CTF > CMF > MPF. The ratio of C/N in both leaf and branch litters was significantly higher in MPF than in CTF and CMF, while no significant differences in N/P ratio were found in these litters among the three forests. The high N:P ratios in leaf litter (23/30) and the branch (24/32) litter indicated the high N returning and low nutrient returning to the soil. Our results suggested that the broadleaved forests have faster litter decomposition and higher macronutrient returns than conifer forests. Moreover, the litter decomposition rate was mainly associated with litterfall quality and chemical composition. The introduction of broadleaved trees into monoculture coniferous stands could increase litter production nutrients return, and thus, it had advantages in soil nutrients restoration and sustainable forest management

Impacts of changed litter inputs on soil CO2 efflux in three forest types in central south China

We have defined Neutrosophic Over-/Under-/Off-Set and Logic for the first time in 1995 and published in 2007. During 1995-2016 we presented them to various national and international conferences and seminars. These new notions are totally different from other sets/logics/probabilities. We extended the neutrosophic set respectively to Neutrosophic Overset {when some neutrosophic component is > 1}, to Neutrosophic Underset {when some neutrosophic component is < 0}, and to Neutrosophic Offset {when some neutrosophic components are off the interval [0, 1], i.e. some neutrosophic component > 1 and other neutrosophic component < 0}. This is no surprise since our real-world has numerous examples and applications of over-/under-/off-neutrosophic components

High-density marker profiling confirms ancestral genomes of Avena species and identifies D-genome chromosomes of hexaploid oat

We investigated genomic relationships among 27 species of the genus Avena using high-density genetic markers revealed by genotyping-by-sequencing (GBS). Two methods of GBS analysis were used: one based on tag-level haplotypes that were previously mapped in cultivated hexaploid oat (A. sativa), and one intended to sample and enumerate tag-level haplotypes originating from all species under investigation. Qualitatively, both methods gave similar predictions regarding the clustering of species and shared ancestral genomes. Furthermore, results were consistent with previous phylogenies of the genus obtained with conventional approaches, supporting the robustness of whole genome GBS analysis. Evidence is presented to justify the final and definitive classification of the tetraploids A. insularis, A. maroccana (=A. magna), and A. murphyi as containing D-plus-C genomes, and not A-plus-C genomes, as is most often specified in past literature. Through electronic painting of the 21 chromosome representations in the hexaploid oat consensus map, we show how the relative frequency of matches between mapped hexaploid-derived haplotypes and AC (DC)-genome tetraploids vs. A- and C-genome diploids can accurately reveal the genome origin of all hexaploid chromosomes, including the approximate positions of inter-genome translocations. Evidence is provided that supports the continued classification of a diverged B genome in AB tetraploids, and it is confirmed that no extant A-genome diploids, including A. canariensis, are similar enough to the D genome of tetraploid and hexaploid oat to warrant consideration as a D-genome diploid.publishersversionPeer reviewe

Optimal Cable Tension Distribution of the High-Speed Redundant Driven Camera Robots Considering Cable Sag and Inertia Effects

Camera robots are high-speed redundantly cable-driven parallel manipulators that realize the aerial panoramic photographing. When long-span cables and high maneuverability are involved, the effects of cable sags and inertias on the dynamics must be carefully dealt with. This paper is devoted to the optimal cable tension distribution (OCTD for short) of the camera robots. Firstly, each fast varying-length cable is discretized into some nodes for computing the cable inertias. Secondly, the dynamic equation integrated with the cable inertias is set up regarding the large-span cables as catenaries. Thirdly, an iterative optimization algorithm is introduced for the cable tension distribution by using the dynamic equation and sag-to-span ratios as constraint conditions. Finally, numerical examples are presented to demonstrate the effects of cable sags and inertias on determining tensions. The results justify the convergence and effectiveness of the algorithm. In addition, the results show that it is necessary to take the cable sags and inertias into consideration for the large-span manipulators

The Comparison of Microwave Thawing and Ultra-High-Pressure Thawing on the Quality Characteristics of Frozen Mango

As one of the popular tropical fruits, mango has a relatively short shelf life due to its perishability. Therefore, post-harvest losses are always a topic of concern. Currently, freezing is a common approach to extending mango shelf life. In relation, it is also critical to select a proper thawing process to maintain its original quality attributes. In this study, microwave thawing, and ultra-high-pressure thawing were investigated, and traditional thawing methods (air thawing and water thawing) were compared as references. The thawing time, quality attributes, and sensory scores of frozen mangoes were evaluated. Compared to traditional methods, innovative thawing methods can extensively shorten thawing time. These things considered, the thawing time was further decreased with the increase in microwave power. Additionally, microwave thawing enhanced the quality of mangoes in terms of less color change and drip loss and reduced loss of firmness and vitamin C content. Microwave thawing at 300 W is recommended as the best condition for thawing mangoes, with the highest sensory score. Current work provides more data and information for selecting suitable thawing methods and optimum conditions for frozen mango to minimize losses

On the Minimum Cable Tensions for the Cable-Based Parallel Robots

This paper investigates the minimum cable tension distributions in the workspace for cable-based parallel robots to find out more information on the stability. First, the kinematic model of a cable-based parallel robot is derived based on the wrench matrix. Then, a noniterative polynomial-based optimization algorithm with the proper optimal objective function is presented based on the convex optimization theory, in which the minimum cable tension at any pose is determined. Additionally, three performance indices are proposed to show the distributions of the minimum cable tensions in a specified region of the workspace. An important thing is that the three performance indices can be used to evaluate the stability of the cable-based parallel robots. Furthermore, a new workspace, the Specified Minimum Cable Tension Workspace (SMCTW), is introduced, within which all the minimum tensions exceed a specified value, therefore meeting the specified stability requirement. Finally, a camera robot parallel driven by four cables for aerial panoramic photographing is selected to illustrate the distributions of the minimum cable tensions in the workspace and the relationship between the three performance indices and the stability

The Comparison of Microwave Thawing and Ultra-High-Pressure Thawing on the Quality Characteristics of Frozen Mango

As one of the popular tropical fruits, mango has a relatively short shelf life due to its perishability. Therefore, post-harvest losses are always a topic of concern. Currently, freezing is a common approach to extending mango shelf life. In relation, it is also critical to select a proper thawing process to maintain its original quality attributes. In this study, microwave thawing, and ultra-high-pressure thawing were investigated, and traditional thawing methods (air thawing and water thawing) were compared as references. The thawing time, quality attributes, and sensory scores of frozen mangoes were evaluated. Compared to traditional methods, innovative thawing methods can extensively shorten thawing time. These things considered, the thawing time was further decreased with the increase in microwave power. Additionally, microwave thawing enhanced the quality of mangoes in terms of less color change and drip loss and reduced loss of firmness and vitamin C content. Microwave thawing at 300 W is recommended as the best condition for thawing mangoes, with the highest sensory score. Current work provides more data and information for selecting suitable thawing methods and optimum conditions for frozen mango to minimize losses