Advanced Materials Research Vols. 726-731

Abstract: An indoor low temperature experiment was conducted to study the variations of membrane permeability, malondialdehyde, soluble protein and soluble sugar contents, superoxide dismutase (SOD) and peroxidase (POD) activities and membrane lipid fatty acid content in leaves and roots of sympodial bamboo seedlings (Dendrocalamus latiflorus) under different levels of cold stress. Results showed that after low temperature pretreatment (8 °C) for 15 days, the soluble protein, soluble sugar contents and POD activities in leaves as well as soluble sugar contents and POD activities in roots were increased obviously. After cold-hardening (-2 °C) for 72 h, the soluble protein, soluble sugar contents and SOD, POD activities in leaves and SOD, POD activities and ratio of membrane lipid unsaturated fatty acid in roots with pretreatment were obviously higher than those without pretreatment. Membrane permeability in leaves with pretreatment was obviously lower than that without pretreatment. But the level of membrane lipid peroxidation in leaves with pretreatment was significantly greater than that before cold-hardening. While the level of membrane permeability and lipid peroxidation in roots with pretreatment had no significant change after cold-hardening. Overall, leaves had higher soluble protein, soluble sugar contents and POD activities to avoid low temperature injuries while roots had higher SOD, POD activities and unsaturated fatty acid to avoid membrane lipid peroxidation and membrane injuries.

Abstract: Litterfall production was shown to have a significant linear relationship with NPP in both natural and planted forests (R² = 0.67, 0.30, P<0.001). Correlation of litterfall production and climatic factors was higher in natural forest than in planted forest. Through correlative and path analyses, it was found that the climatic factors that most affect litterfall production in natural forest are annual mean maximum temperature, annual mean minimum temperature, annual extreme minimum temperature, and relative humidity, but in planted forest, they are annual extreme minimum temperature and annual mean minimum temperature. In both natural and planted forests, climatic factors could not account for the error in litterfall production predicted using the NPP.

Abstract: The relations between the scales and periods of Mexican Hat (Mexh) and Morlet (Morl) wavelets have been deduced. Based on these relations, variances, coefficients, and power spectra of these two wavelets’ original and eco-used wavelets are compared and analyzed theoretically and experimentally for the distribution pattern of Haloxylon ammodendron Bunge population in Gurban Tonggut desert, China. The research shows that: (1) Mexh and Morl eco-used wavelets can be simultaneously used to describe the distribution period of Haloxylon population and to study the same phenomenon by combining these two wavelet advantages. (2) The primary period value identified using Mexh eco-used wavelet than using its original wavelet is closer to the true one, while Morl eco-used wavelet helps find all changes in the period earlier. (3) For the same wavelet function, with its period enlarging, its primary period can be found in a smaller scale, inversely found later.

Abstract: The land cover maps of Hangzhou in 2000、2005 and 2010 are generated based on object-oriented method using multi-temporal TM/ETM+ images for the analysis of the forest distrabution and change detection.. The paper focuses on the method of the extraction of forest information, especialy the analysis of the characteristic variables that can be used for classification. LBV transformation,the K-T transformation and vegetation index are studies for various types of the forests, and the appropriate rules and parameters are derived accordingly to extract the forest information. The paper also illustrates the spatial distribution of the dynamic change of forest resource by analysing the land cover of three years .At last, the type and the proportion of the forests dynamic change are statistical calculated, and the driving forces for the change are analyzed to provide the decision-making basis for the relevant department.

Abstract: In order to investigate the effect of stand age and climate hydrothermic factors on aboveground biomass accumulation (ABA), data from 65 typical Pinus tabulaeformis forest stands were compiled from published literatures. By means of stepwise multiple regression, the variations in ABA were examined across the range of stand age and gradients of mean annual precipitation (MAP) and mean annual temperature (MAT). For comparison, stand age was also used as explaining variable alone. The results show that, stand age and MAP could explain 85.1% of variation in ABA, the predictive power is much better than stand age alone. The explanatory power of stand age and MAP were 70.7% and 15.3% respectively. In comparison with stand age, MAP has a relatively poor but significant effect. ABA is not significantly related to MAT, which implies that water availability is more important than thermal condition for ABA of Pinus tabulaeformis forests.

Abstract: We have carried out three consecutive years of tree growth survey, and studied on afforestation technology, compatibility and high-yielding measures, we conducted two-factor effect analysis of different varieties and different density on seedling height and ground diameter in the annual introduction of fast-growing poplar. The results showed that the influence of different varieties of seedling height and ground diameter was extremely significant, and the influence of different density of seedling height and ground diameter was not significant basically. Based on the above results, it can be preliminarily determined the most suitable fast-growing poplar and planting density for Inner Mongolia Daxinganling Forest Region.

Abstract: The carbon sequestration ability of different ages of Phyllostachys pubescens was analyzed at three canopy layers with a LI-6400 portable photosynthesis system. Under different photosynthetically active radiation (PAR), the net photosynthetic rate (Pn) of upper and middle layers of 3-year old bamboo were significantly higher than that of lower layer. When the light was greater than 800 umol·m-2·s-1, the Pn of bamboo in middle layer was in the order of 3-year-old > 4-year- old >2-year-old >7-year-old bamboo. When the light was greater than 500 umol·m-2·s-1, Pn of lower layer was in the order of 3-year old > 4-year old >2-year old, while in the order of 3-year-old > 2-year -old >4-year-old bamboo during the low light range (PAR<200 umol·m-2·s-1).The chlorophyll a/b value, maximum net photosynthetic rate, light compensation point and light saturation point values change were reduced gradually with the decrease of canopy height.

Abstract: This article deals with comparison of the behaviour of spruce wood and polyolefins (polyethylene PE and polypropylene PP) during the test on the cone calorimeter. Samples were tested on the cone calorimeter at heat flux of 20 and 40 kW/m². An evaluation of the behaviour of examined materials was based on the determination of the maximum and the average heat release rate, yield of carbon monoxide (CO), and relative comparison of tendency to fire propagation in a flashover phase. The tendency of materials to fire propagation in the flashover phase was evaluated based on the Pearson ́s correlation, the Spearman ́s correlation and the Kendall ́s correlation coefficient of HRR-CO and CO2-CO. Spruce wood showed better properties in comparison with PE and PP in all evaluated parameters (the maximum and the average heat release rate, the yield of CO, and also the resistance to fire propagation in the flashover phase. Additionally, spruce wood showed significantly lower sensitivity of dependence of the maximum and also the average heat release rate on external heat flux.

Abstract: Anthropogenic disturbance measures have complex effects on understory plants. In order to establish a theoretical basis for moso bamboo forest sustainable management, three types of moso bamboo forests with many years not weeding, hilltops weeding and herbicides weeding were choosed. And species names, numbers and coverages of all arbors, shrubs, herbs and vines were recorded in every quadrat. Species composition and α-diversity were analyzed to compare understory vegetation under the three types of moso bamboo forests with consistent stand structure and site conditions. There are four major findings in this study: (1) 74 species belonged to 47 families and 58 generas which are recorded in the three types of moso bamboo forests. Many years not weeding, hilltops weeding and herbicides weeding are respectively 33 families 39 genera 40 species, 33 families 37 genera 41 species and 37 families 43 genera 49 species. (2) Dominant species of arbors and shrubs within hilltops weeding and herbicides weeding moso bamboo forests are less than the ones of many years not weeding moso bamboo forest, whereas dominant species of herbs increased. Meanwhile, co-dominant specie of arbors is Cunninghamia lanceolata, shrubs is Rubus reflexus, and herbs are Melastoma dodecandrum and Dicranopteris dichotoma. (3) Richness of herbicides weeding and hilltops weeding moso bamboo forests is significantly lower than (p<0.05) the one of many years not weeding moso bamboo forest, and Containing absolute abundance diversity index (I) of hilltops weeding moso bamboo forest is also significantly lower than (p<0.01) many years not weeding moso bamboo forest. The differences of Simpson dominance index (C), Simpson diversity index (D),Shannon-Wiener diversity index (H) and Pielou evenness index (J) among the three types of moso bamboo forests are not significant. Considering understory plant diversity and system structure stability analysis, anthropogenic hilltops weeding measure is suggested to be used for understory vegetation interference.

Abstract: Forest ecosystem plays an important role in regulating global carbon cycle and climate change, to estimate its carbon storage, this study selected five major forest types in Northeast and investigated its tree, understory vegetation, forest floor and soil carbon density based on field measurement. Subsequently, we combined with the 7th Forest Resources Statistics of China to calculate forest carbon storage under the natural forest protection program in Northeast on regional scale. Results showed that forest ecosystem carbon storage under the natural forest protection program in Northeast was 4603.8 TgC, in which tree, understory, forest floor and soil carbon storages account for 22.7%, 0.9%, 6.5% and 69.9% respectively. Forest ecosystem carbon density was 180.6 Mg/ha, and tree, understory, and forest floor carbon density all increased with age class, which imply the great forest carbon sequestration potential under the natural forest protection program in Northeast.