Advanced Materials Research Vols. 518-523

Abstract: We studied a ramet population of switchgrass, caespitose in appearance, and proved the absence of density-dependent mortality. We present a deviation of mass-density allometry based on spatially explicit densities along the vertical space of the population. The number of ramets in the mean-ramet-height space explains the variation in the average weight of whole ramets (M) more accurately, with an asymptote towards critical self-thinning trajectory for such a mass-density relationship. With the development of size heterogeneity, a ‘vertical packing’ process appears in the population. We define the process as a similar ‘self-thinning’ trajectory, through the initial crowding of ramets in the mean-ramet-height space and continued transferring into the upper space and the lower space. The process presents a possibly competitive mechanism of self-thinning, local-competition-driving size deviation and vertical space packing. Here, log10 (M) = 2.91 - 1.25 log10 (N_L). Local crowding degree (N_L) is the number of ramets per unit area (m₂) in the mean-ramet-height space class. Similar ‘self-thinning’ occurs in the ramet population, but it just indicates how those ramets escape out of the mean-ramet-height space class, and therefore how the mean weight of whole ramets increases. Self-thinning should be the result of local competition among effective number of individuals in a population, rather than apparent crowding degree presented by whole individuals. The critical mass-density allometry based on whole individuals should be only a special case.

Abstract: In this paper, the effects of different LiDAR point density on individual tree parameters including tree height and crown diameter were investigated for the coniferous tree species in the Qilian Mountain area within Gansu province, western China. 10 different density data were acquired in field survey area, with the minimum density of 0.234 points/m2 and the maximum density of 0.6941 points/m2 for per flight. By summing up the different flight data, the different density LIDAR data from 0.234 points/m2 to 5.226 points/m2 for extracting tree height and crown diameter can be analyzed. The result showed that the number of extraction points and the extraction accuracy of tree height and crown width arrived at relative high level in point density of about 2.5 points per m2. When the point density increased, the increased extraction points and the extraction accuracy of tree height and crown width became slow. It means that about 2.5 points per m2 of LiDAR data density may provide relative high accurate individual tree parameters estimation.

Abstract: Distribution pattern of 1148 indigenous tree species in Guangdong province and their relations to the environment were investigated based on the 0.5°×0.5° latitude-longitude grid system. The results showed that indigenous tree species richness increased with increasing latitude. Richness peaked in the middle of the study area with longitudinal gradient. Four ecological areas for indigenous tree species distribution were delimited using cluster analysis and TWINSPAN (two-way indicator species analysis). Indicator Species Analysis showed a significant difference was found in indicator species distribution across latitude gradient and the 4 ecological areas. Northern mountain areas and southern coastal areas possessed most of the indicator species (IV ≥ 0.7), among which Celtis philippensis, Gironniera cuspidata and Symplocos chunii were strongly indicative of the environmental characteristics. The study of distribution patterns and classification of ecological areas, which reflects different geographical and climatic characteristics, will be of significant implications for introduction of indigenous tree species from natural ecological areas.

Abstract: In order to explore the effects of salt stress on root configuration. This research take the root of Jatropha curcas L as object, a method was proposed that was to statistically analysis root space distribution by Otsu and based on it's morphological and growing characteristic after partitioning root image. Using image processing library to obtain the spatial distribution statistical matrix by the Python language programming, 3D visualization root model was established for Jatropha curcas L with SimRoot root structure model as geometric prototype by using the Visual C++ and OpenAlea model under different salt levels. The results show that this method can scientifically simulate the influence salt stress on Jatropha curcas L root topological.

Abstract: Biomass density and carbon density were estimated for the forest stands along the Dongjiang River basin of eastern Guandong, China. Total biomass density and carbon density for the Huangtian, Longcun, and Yihe plots were 191.5606 Mg ha^-1 and 95.7803 Mg ha^-1, 229.6908 Mg ha^-1 and 114.8454 Mg ha^-1, and 321.1667 Mg ha^-1 and 160.5834 Mg ha^-1, respectively; while the economic value of forest carbon stock for the three forest stands (1 ha each) was 30699.50 CNY, 51470.19 CNY, and 36810.25 CNY calculated using silviculture cost model, and 108062.21 CNY, 181175.01 CNY, and 129572.02 CNY using carbon tax model, respectively. The results revealed that the forest carbon density of Dongjiang River basin was much higher than the average value of Guangdong province and the carbon density was closely related to stand structure, forest age, and wood type.

Abstract: Pseudolarix amabilis is a rare and endangered tree species in China. With the method of spatial sere substituting for time sere, by the size structure in place of age structure, using life stable, survival analysis, the structure and dynamics of P. amabilis population at Yaoluoping Natural reserve of Anhui Province was studied. Based on the life table of population and the theory of survival analysis, we worked out the life table of P. amabilis population drew the curves of mortality density function, hazard rate function and survival, and analyzed the population dynamics. The resulted showed that, along the altitude, the population density increased, distribution range of size class decreased. It indicated that the survival curve of the population trended to the type of Deevey Ⅱ.

Abstract: The successful cultivation of aerobic granular sludge used for simultaneous nitrogen and phosphorus removal in sequencing batch reactor (SBR) was performed using a synthetic domestic wastewater and conventional flocculent activated sludge as seeding sludge. The removal efficiency of sludge for chemical oxygen demand (COD),ammonia nitrogen and phosphate was 92.4%,88.1% and 95.9%, respectively. After screening, a strain was obtained with high efficient in nitrogen and phosphorus removal. By analyzing, the strain was identified as Raoultella ornithinolytica. After strain accumulation, the strain cultured at 30°C for 24h. The ammonia nitrogen and phosphate removal efficiency were 78.3% and 92%, respectively.

Abstract: Due to human factors, plant introduction that makes the introduced plants cross over insurmountable space boundary under the natural brings benefits to people, but it may give rise to biodiversity decrease, genetic pollution, and habitat destruction and so on. In addition, the exotic plants may also become invasive species, leading to the ecological disaster in new habitat. It is more effective to avoid the risks of plant introduction by taking such following actions: enhancing ecological safety consciousness, strengthening the study on risk mechanism about plant introduction, establishing the introduction risk assessment system suitable for their own national characteristics, strengthening the effective supervision of the plant introduction and making the introduced plants and the local native plants realize the reproductive isolation in space-time and so on.

Abstract: The aim of this experiment was to determine the responses of reed canary grass (Phalaris arundinacea L.) to salt stress during germination and vegetative growth. Therefore, effects of salinity (0, 50, 100,150, 200,250mMNaCl) on germination, changes in the percentage of germination, abnormal seedling and un-germinated seeds of two germplasms (Zxy06p-2449 and Zxy06p-2653) during germination under stress were determined. Moreover, during vegetative growth(40d old plants), changes in superoxide dismutase(SOD), peroxidase(POD), catalase (CAT), electrolyte leakage were also investigated after salt treatment for 5,10 and 15d. Salt stress decreased the germination percentage. Few seeds germinated at 200mMNaCl, abnormal seedlings and un-germinated seeds increased significantly under the higher salt concentration. During vegetative growth, increased activities of SOD, in 50,100 and 150mMNaCl treated-plants may help to avoid oxidative damage. Differential responses of antioxidant enzymes to salt stress during germination and vegetative growth suggested different antioxidant metabolism in reed canary grass. From the results obtained in present study, it can be suggested that reed canary grass is a moderately salt-tolerant specie with considerable germplasm differences. Zxy06p-2449 and Zxy06p-2653 will not be survive in long-term (>15d) salt treatment under 150mMNaCl, especially Zxy06p-2653 which shown more sensitive under higher salt concentrations

Abstract: In order to ascertain the allelopathy of Reed on Alligator Weed, the water culture experiments were performed to investigate the effects of aqueous extract on the growth, physiological and biochemical mechanism in Alligator Weed. The results showed that aqueous extract of Reed inhibited the growth of Alligator Weed, and the inhibition became stronger as the concentration of the extract increased. Some results from physiological and biochemical mechanism of treated Alligator Weed indicated that with the increase of extract concentration, photosynthetic pigment contents, root activity and CAT activity decreased, while P and MDA contents increased; N content decreased first and then up to normal. The results showed that aqueous extract of Reed inhibited the photosynthesis, CAT activities of Alligator Weed but increased the MDA content of Alligator Weed.