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forest fractals

Ke Yi Chen, Hui Ru Zhang, Xiang Dong Lei
Taking Quercus mongolica population in the secondary forest of Q. mongolica as the research object, two plots in different stages of succession (A and B) were set up in Tazigou Forest Farm of Wangqing Forestry Bureau, Jilin Province. By applying the method of adjacent grid survey, each plot was divided into 100 units of 10 m×10 m and the spatial coordinates of each tree in the unit were accurately located to survey all the basic information of trees with diameter at breast height (DBH)≥1 cm. The degree, composition, scale and pattern of spatial heterogeneity of individual tree of Q...
May 2018: Ying Yong Sheng Tai Xue Bao, the Journal of Applied Ecology
Kun Li, Huanxiang Yang, Xu Han, Lingyu Xue, Yang Lv, Jinhua Li, Zhanyong Fu, Chuanrong Li, Weixing Shen, Huiling Guo, Yikun Zhang
To study the fractal dimensions of the soil particle size distributions (PSDs) within different plantations (of Pinus densiflora, Quercus acutissima, Robinia pseudoacacia, and Larix kaempferi) and evaluate PSDs as an indicator of the likelihood of Robinia pseudoacacia invasion, the soil porosity of 0-20 cm soil layers was measured at different plantations in the Yaoxiang Forest Farm, Shandong Province, China. The results showed that the fractal dimension (Dm ) values varied from 2.59 to 2.70 among the different plantations and were significantly negatively correlated to sand content and positively correlated to silt content and clay content...
May 4, 2018: Scientific Reports
Franziska Taubert, Rico Fischer, Jürgen Groeneveld, Sebastian Lehmann, Michael S Müller, Edna Rödig, Thorsten Wiegand, Andreas Huth
Remote sensing enables the quantification of tropical deforestation with high spatial resolution. This in-depth mapping has led to substantial advances in the analysis of continent-wide fragmentation of tropical forests. Here we identified approximately 130 million forest fragments in three continents that show surprisingly similar power-law size and perimeter distributions as well as fractal dimensions. Power-law distributions have been observed in many natural phenomena such as wildfires, landslides and earthquakes...
February 22, 2018: Nature
Dominik Seidel
The three-dimensional forest structure affects many ecosystem functions and services provided by forests. As forests are made of trees it seems reasonable to approach their structure by investigating individual tree structure. Based on three-dimensional point clouds from laser scanning, a newly developed holistic approach is presented that enables to calculate the box dimension as a measure of structural complexity of individual trees using fractal analysis. It was found that the box dimension of trees was significantly different among the tested species, among trees belonging to the same species but exposed to different growing conditions (at gap vs...
January 2018: Ecology and Evolution
Xènia Albà, Karim Lekadir, Marco Pereañez, Pau Medrano-Gracia, Alistair A Young, Alejandro F Frangi
Continuous advances in imaging technologies enable ever more comprehensive phenotyping of human anatomy and physiology. Concomitant reduction of imaging costs has resulted in widespread use of imaging in large clinical trials and population imaging studies. Magnetic Resonance Imaging (MRI), in particular, offers one-stop-shop multidimensional biomarkers of cardiovascular physiology and pathology. A wide range of analysis methods offer sophisticated cardiac image assessment and quantification for clinical and research studies...
January 2018: Medical Image Analysis
Xinping Zhang, Dexiang Wang, Hongke Hao, Fangfang Zhang, Youning Hu
In this study Yan'an City, a typical hilly valley city, was considered as the study area in order to explain the relationships between the surface urban heat island (SUHI) and land use/land cover (LULC) types, the landscape pattern metrics of LULC types and land surface temperature (LST) and remote sensing indexes were retrieved from Landsat data during 1990-2015, and to find factors contributed to the green space cool island intensity (GSCI) through field measurements of 34 green spaces. The results showed that during 1990-2015, because of local anthropogenic activities, SUHI was mainly located in lower vegetation cover areas...
July 26, 2017: International Journal of Environmental Research and Public Health
Laura Marcela Palma Medina, Diana Catalina Ardila, María Mercedes Zambrano, Silvia Restrepo, Andrés Fernando González Barrios
Diversification of raw material for biofuel production is of interest to both academia and industry. One attractive substrate is a renewable lignocellulosic material such as oil palm (Elaeis guineensis Jacq.) empty fruit bunch (OPEFB), which is a byproduct of the palm oil industry. This study aimed to characterize cellulases active against this substrate. Cellulases with activity against OPEFB were identified from a metagenomic library obtained from DNA extracted from a high-Andean forest ecosystem. Our findings show that the highest cellulolytic activities were obtained at pH and temperature ranges of 4-10 and 30 °C-60 °C, respectively...
September 2017: Biotechnology Reports
Jinxiang Xi, Weizhong Zhao, Jiayao Eddie Yuan, Biwei Cao, Linlin Zhao
Exhaled aerosol patterns have been used to detect obstructive respiratory diseases in the upper airways. Signals from small airway diseases are weak and may not manifest themselves in the exhaled aerosol patterns. Therefore, it will be more challenging to detect abnormalities in small airways. The objective of this study is to develop a simulation-based classification model that can accurately classify small airway diseases. The model performance was evaluated in five obstructed models that are located in lung bifurcations G7-9...
August 1, 2017: Computers in Biology and Medicine
Qian Xu, Yuxiang Dong, Ren Yang
This study analyzed carbon fixation across different land use types in the Pearl River Delta to identify the influence of different geographical factors on carbon fixation ability. The methodology was based on interpreting land use data from TM imagery, MODIS13Q1 data, and climate data, using the improved CASA and GeogDetector models. The results show that: (1) From 2000 to 2013, the total carbon sink increased slightly, from 15.58 × 106 t to 17.52 × 106 t, being spatially low at the center and increasing outwards; (2) Proxy variables (topography and landform characteristics), influencing urbanization, significantly affect the carbon sink function of the Pearl River Delta region...
March 8, 2017: Scientific Reports
Maria Rosário Fernandes, Pedro Segurado, Eduardo Jauch, Maria Teresa Ferreira
Climate change will induce alterations in the hydrological and landscape patterns with effects on riparian ecotones. In this study we assess the combined effect of an extreme climate and land-use change scenario on riparian woody structure and how this will translate into a future risk of riparian functionality loss. The study was conducted in the Tâmega catchment of the Douro basin. Boosted Regression Trees (BRTs) were used to model two riparian landscape indicators related with the degree of connectivity (Mean Width) and complexity (Area Weighted Mean Patch Fractal Dimension)...
November 1, 2016: Science of the Total Environment
Wei-jun Zhao, Xian-de Liu, Wen-mao Jing, Li-heng Xu, Yun Niu, Peng Qi, Yong-hong Zhao
We selected the grid of 5 m x 5 m in a dynamic monitoring plot (340 m x 300 m) as the sampling unites and chose 5 structural characteristics (density, average crown breadth, coverage, conspicuousness and average height) to study the spatial heterogeneity of community structure of Picea crassifolia forest in Dayekou Basin of Qilian Mountains by the fractal geometry and geostatistics methods. The results showed that the order of spatial variation in these characteristics was: density > average crown breadth > conspicuousness > coverage > average height, with the variation coefficient ranging from 43...
September 2015: Ying Yong Sheng Tai Xue Bao, the Journal of Applied Ecology
Luping Ye, Linchuan Fang, Wenfeng Tan, Yunqiang Wang, Yu Huang
A GIS approach and HJ-1B images were employed to determine the effect of landscape structure on aerosol optical depth (AOD) patterns. Landscape metrics, fractal analysis and contribution analysis were proposed to quantitatively illustrate the impact of land use on AOD patterns. The high correlation between the mean AOD and landscape metrics indicates that both the landscape composition and spatial structure affect the AOD pattern. Additionally, the fractal analysis demonstrated that the densities of built-up areas and bare land decreased from the high AOD centers to the outer boundary, but those of water and forest increased...
February 2016: Environmental Science. Processes & Impacts
Georgios Leontidis, Bashir Al-Diri, Jeffrey Wigdahl, Andrew Hunter
Diabetic retinopathy (DR) has been widely studied and characterized. However, until now, it is unclear how different features, extracted from the retinal vasculature, can be associated with the progression of diabetes and therefore become biomarkers of DR. In this study, a comprehensive analysis is presented, in which four groups were created, using eighty fundus images from twenty patients, who have progressed to DR and they had no history of any other diseases (e.g. hypertension or glaucoma). The significance of the following features was evaluated: widths, angles, branching coefficient (BC), angle-to-BC ratio, standard deviations, means and medians of widths and angles, fractal dimension (FD), lacunarity and FD-to-lacunarity ratio, using a mixed model analysis of variance (ANOVA) design...
2015: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
Xiang Niu, Peng Gao, Bing Wang, Yu Liu
Based on fractal theory, the fractal characteristics of soil particle size distribution (PSD) and soil water retention curve (WRC) under the five vegetation types were studied in the mountainous land of Northern China. Results showed that: (1) the fractal parameters of soil PSD and soil WRC varied greatly under each different vegetation type, with Quercus acutissima Carr. and Robina pseudoacacia Linn. mixed plantation (QRM) > Pinus thunbergii Parl. and Pistacia chinensis Bunge mixed plantation (PPM) > Pinus thunbergii Parl...
December 2015: International Journal of Environmental Research and Public Health
Dalu Yang, Ganesh Rao, Juan Martinez, Ashok Veeraraghavan, Arvind Rao
PURPOSE: Glioblastoma multiforme (GBM) is the most common and aggressive primary brain cancer. Four molecular subtypes of GBM have been described but can only be determined by an invasive brain biopsy. The goal of this study is to evaluate the utility of texture features extracted from magnetic resonance imaging (MRI) scans as a potential noninvasive method to characterize molecular subtypes of GBM and to predict 12-month overall survival status for GBM patients. METHODS: The authors manually segmented the tumor regions from postcontrast T1 weighted and T2 fluid-attenuated inversion recovery (FLAIR) MRI scans of 82 patients with de novo GBM...
November 2015: Medical Physics
Changge Guan, Xiaohui Niu, Feng Shi, Kun Yang, Nana Li
DNA-binding proteins are involved and play a crucial role in a lot of important biological processes. Hence, the identification of the DNA-binding proteins is a challenging and significant problem. In order to reveal the intrinsic information correlated to DNA-binding, nine classes of candidate features based on different mathematical fields are applied to construct the prediction model with random forest. They are fractal dimension, conjoint triad feature, Hilbert-Huang Transformation, amino acid composition, dipeptide composition, chaos game representation, and the corresponding information entropies...
2015: Bio-medical Materials and Engineering
Jun-xia Yan, Hong-jian Li, Jun-jian Li, Jiang-xing Wu
Based on the data from a planted larch forest in Panquangou Natural Reserve of Shanxi Province, at three sampling scales (4, 2, and 1 m, respectively), soil respiration (Rs) and its affecting factors including soil temperature at 5 cm (T5), 10 cm (T10), and 15 cm (T15) depths, soil water content (Ws), litter mass (Lw), litter moisture (Lm), soil total carbon (C), and soil total nitrogen ( N) were determined. The spatial heterogeneities of Rs and the environmental factors were further analyzed and their intrinsic correlations were established...
May 2015: Huan Jing Ke Xue= Huanjing Kexue
Mahla Hosseini Vardei, Abdolrasoul Salmanmahiny, Seyed Masoud Monavari, Mir Masoud Kheirkhah Zarkesh
Population growth, during the twentieth century, has increased demand for new farmlands. Accordingly, road networks have rapidly been developed to facilitate and accelerate human access to the essential resources resulted in extensive land use changes. The present study aims at assessing cumulative effects of developed road network on tree cover of Golestan Province in northern Iran. In order to detect changes over the study period of 1987-2002, the LULC map of the study area was initially prepared from the satellite images of Landsat TM (1987) and ETM+ (2002) using maximum likelihood supervised classification method...
November 2014: Environmental Monitoring and Assessment
Qiu-Jin Tan, Tong-Qing Song, Wan-Xi Peng, Fu-Ping Zeng, Hu Du, Gai-Ren Yang, Fu-Jing Fan
Soil aggregates and their organic carbon distributions were studied under six ecosystems, i. e., farmland (short for ST), dry land (HD), grassland (CD), shrubbery (GC), plantation (RGL) and secondary forest (CSL), in a karst canyon region of China by a combination of field investigation and laboratory analysis. The result showed that, soil aggregates were dominated by particles with sizes>8 mm in the ecosystems except HD under dry sieving, and basically presented a trend of decreasing firstly, then increasing and finally decreasing along with particle sizes decreasing; while soil aggregates were dominated by particles with sizes > 5 mm in the ecosystems except HD under wet sieving and decreased with decreasing of particle sizes...
March 2014: Ying Yong Sheng Tai Xue Bao, the Journal of Applied Ecology
Yan-Li Li, Hua Yang, Xin-Gang Kang, Yan Wang, Gang Yue, Lin Shen
Based on fieldwork on a plot of 60 m x 60 m in the Changbai Mountain area of Northeast China in August 2012, the spatial distribution pattern and heterogeneity of natural regeneration in the spruce-fir mixed broadleaf-conifer forest were analyzed using semi-variograms, fractal dimensions and Kriging interpolation methods. The results showed that Abies nephrolepis and Acer mono were the most common regeneration species, accounting for 87.4% of the total. The regeneration seedlings and saplings presented an aggregate distribution pattern with the biggest radius of 9...
February 2014: Ying Yong Sheng Tai Xue Bao, the Journal of Applied Ecology
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