Road network detection based on improved FLICM-MRF method using high resolution SAR images

The automatic detection of road network from satellite and aerial images is highly significant in many actual applications, for instance, urban traffic measurement, military emergency response, and vehicle target tracking. Compared with other high-resolution satellite remote sensing images, high-resolution synthetic aperture radar (SAR) has become a popular research perspective for road detection owing to its insensitivity to the atmosphere and sun-illumination. However, the method of road network detection is still lagging due to the strong multiplicative speckle noise and complex background interference, causing the loss and break in the road segment extraction results. Aiming to solve this problem, a three-step road network detection framework is proposed. In the first step, the road segment candidates are extracted by the Fuzzy Local Information C-Means (FLICM) algorithm based on the gray-level co-occurrence matrix(GLCM) with Markov Random Fields (MRF), and it contains an adaptive parameter selection procedure which is presented for adjusting joint clustering parameters. In order to reduce false segments, we perform the local processing which combines the morphological operation, linearity index, and local Hough transform in the second step. Finally, as for the global road segment connection, we propose an improved region growing algorithm which fully considering the rationality of road elements to gain the road network. Compared with the traditional region growing algorithm, the proposed method can effectively promote the improvement of the integrity of the road network detection. Moreover, the performance of the proposed method is evaluated by comparing the results with the ground truth road map and the evaluation index including the completeness, correctness, and quality factor. In experiments, the algorithm has been verified with the SAR images from the different resolutions of the GF-3 satellite SAR image. The results of the various real images demonstrate that the proposed algorithm has improved considerably the adaptability and efficiency of road detection compared with other methods

Prediction of spatial distribution characteristics of ecosystem functions based on a minimum data set of functional traits of desert plants

The relationship between plant functional traits and ecosystem function is a hot topic in current ecological research, and community-level traits based on individual plant functional traits play important roles in ecosystem function. In temperate desert ecosystems, which functional trait to use to predict ecosystem function is an important scientific question. In this study, the minimum data sets of functional traits of woody (wMDS) and herbaceous (hMDS) plants were constructed and used to predict the spatial distribution of C, N, and P cycling in ecosystems. The results showed that the wMDS included plant height, specific leaf area, leaf dry weight, leaf water content, diameter at breast height (DBH), leaf width, and leaf thickness, and the hMDS included plant height, specific leaf area, leaf fresh weight, leaf length, and leaf width. The linear regression results based on the cross-validations (FTEIW - L, FTEIA - L, FTEIW - NL, and FTEIA - NL) for the MDS and TDS (total data set) showed that the R2 (coefficients of determination) for wMDS were 0.29, 0.34, 0.75, and 0.57, respectively, and those for hMDS were 0.82, 0.75, 0.76, and 0.68, respectively, proving that the MDSs can replace the TDS in predicting ecosystem function. Then, the MDSs were used to predict the C, N, and P cycling in the ecosystem. The results showed that non-linear models RF and BPNN were able to predict the spatial distributions of C, N and P cycling, and the distributions showed inconsistent patterns between different life forms under moisture restrictions. The C, N, and P cycling showed strong spatial autocorrelation and were mainly influenced by structural factors. Based on the non-linear models, the MDSs can be used to accurately predict the C, N, and P cycling, and the predicted values of woody plant functional traits visualized by regression kriging were closer to the kriging results based on raw values. This study provides a new perspective for exploring the relationship between biodiversity and ecosystem function

The Edaphic and Vegetational Properties Controlling Soil Aggregate Stability Vary with Plant Communities in an Arid Desert Region of Northwest China

The stability of soil aggregates is the basis for supporting ecosystem functions and related services provided by the soil. In order to explore the mechanism of the influence of soil and vegetation properties on the stability of soil aggregates in desert communities, the particle size distribution and aggregate in different communities were compared, and the contribution of soil physical and chemical properties (soil salinity, soil water content, soil pH, soil organic carbon, soil total phosphorus, soil total nitrogen, etc.) and vegetation properties (species richness, phylogenetic richness, plant height and coverage, etc.) to the stability of soil aggregates was determined by using a structural equation model. The results show the following: Soil water content, organic carbon, and salt in river bank plant communities have significant direct positive effects on the mean weight diameter of soil, with path coefficients of 0.50, 0.11, and 0.24, respectively (p < 0.01). Water also indirectly affects soil stability by affecting plant height, soil salt, and soil organic carbon; species richness and vegetation coverage have significant direct positive effects on the soil stability index, with path coefficients of 0.13 and 0.11, respectively (p < 0.01). In the desert marginal plant community, the plant coverage and species richness have significant positive effects on soil stability, with path coefficients of 0.43 (p < 0.001) and 0.35 (p < 0.001), respectively. Phylogenetic richness has a significant direct negative effect on soil stability (p < 0.05), with an effect value of −0.27. Phylogenetic richness indirectly affects soil stability by adjusting the coverage, with an indirect effect value of 0.23. Moisture, ammonium nitrogen, and nitrate nitrogen have significant direct positive effects on soil stability, with effect values of 0.12, 0.09, and 0.15, respectively. Our research shows that the process of soil stabilization is mainly controlled by soil factors and vegetation characteristics, but its importance varies with different community types

Functional Diversity Can Predict Ecosystem Functions Better Than Dominant Species: The Case of Desert Plants in the Ebinur Lake Basin

Studying the impact of biodiversity on ecosystem multifunctionality is helpful for clarifying the ecological mechanisms (such as niche complementary effects and selection) of ecosystems providing multiple services. Biodiversity has a significant impact on ecosystem versatility, but the relative importance of functional diversity and dominant species to ecosystem functions needs further evaluation. We studied the desert plant community in Ebinur Lake Basin. Based on field survey data and experimental analysis, the relationship between the richness and functional diversity of dominant species and the single function of ecosystem was analyzed. The relative importance of niche complementary effect and selective effect in explaining the function of plant diversity in arid areas is discussed. There was no significant correlation between desert ecosystem functions (soil available phosphorus, organic matter, nitrate nitrogen, and ammonium nitrogen) and the richness of the dominant species Nitraria tangutorum (p p < 0.05). Functional dispersion (FDis) had a significant effect on soil available phosphorus, while dominant species dominant species richness (SR) had no obvious effect on single ecosystem function. A structural equation model showed that dominant species had no direct effect on plant functional diversity and ecosystem function, but functional diversity had a strong direct effect on ecosystem function, and its direct coefficients of action were 0.226 and 0.422. The results can help to explain the response mechanism of multifunctionality to biodiversity in arid areas, which may provide referential significance for vegetation protection and restoration for other similar areas

Functional Diversity Can Predict Ecosystem Functions Better Than Dominant Species: The Case of Desert Plants in the Ebinur Lake Basin

Studying the impact of biodiversity on ecosystem multifunctionality is helpful for clarifying the ecological mechanisms (such as niche complementary effects and selection) of ecosystems providing multiple services. Biodiversity has a significant impact on ecosystem versatility, but the relative importance of functional diversity and dominant species to ecosystem functions needs further evaluation. We studied the desert plant community in Ebinur Lake Basin. Based on field survey data and experimental analysis, the relationship between the richness and functional diversity of dominant species and the single function of ecosystem was analyzed. The relative importance of niche complementary effect and selective effect in explaining the function of plant diversity in arid areas is discussed. There was no significant correlation between desert ecosystem functions (soil available phosphorus, organic matter, nitrate nitrogen, and ammonium nitrogen) and the richness of the dominant species Nitraria tangutorum (p &lt; 0.05). Soil organic matter and available phosphorus had significant effects on specific leaf area and plant height (p &lt; 0.05). Functional dispersion (FDis) had a significant effect on soil available phosphorus, while dominant species dominant species richness (SR) had no obvious effect on single ecosystem function. A structural equation model showed that dominant species had no direct effect on plant functional diversity and ecosystem function, but functional diversity had a strong direct effect on ecosystem function, and its direct coefficients of action were 0.226 and 0.422. The results can help to explain the response mechanism of multifunctionality to biodiversity in arid areas, which may provide referential significance for vegetation protection and restoration for other similar areas

The Functional Variant in the 3'UTR of IGF1 with the Risk of Gastric Cancer in a Chinese Population

Background/Aims: IGF-1 can act as an endocrine hormone and its signaling server as essential roles in regulating tumorigenesis. Polymorphisms in IGF-1 have been reported associated bad prognosis of with human cancer, but their association with the risk of human gastric cancer (GC) has not been found so far. In this study rs6218 located in the 3'UTR of IGF-1 was selected to evaluate its relationship with the risk of GC among Chinese population. Methods: Questionnaire, SNaPshot genotype assay, real time PCR assay, cell transfection and the dual luciferase reporter assay were used in our study. Results: SNP rs6218 in IGF-1 3'-UTR was involved in the occurrence of GC by acting as a tumor promotion factor while rs6128 acting as a risk factor. SNP rs6128 was also could be regulated by miR-603 which caused an up-regulation of IGF-1 in patients with UC and CC genotype. Furthermore, the carriers of UC and CC genotype presented a big tumor size as well as the high probability of metastasis. Conclusion: In conclusion, our findings have shown that the SNP rs6218 in IGF-1 3'-UTR, through disrupting the regulatory role of miR-603 in IGF-1 expression, rs16128 in IGF-1 might act as a promotion factor in the pathogenesis of GC

Response of Morphological Characters and Photosynthetic Characteristics of Haloxylon ammodendron to Water and Salt Stress

In arid desert areas, Haloxylon ammodendron plays an important role in maintaining the ecological balance of desert oases. However, there are few studies on the physiological characteristics of Haloxylon ammodendron under an environmental gradient. Here, we studied the changes in the morphological and photosynthetic characteristics and their correlations in Haloxylon ammodendron in the four habitats of the Ebinur Lake wetland. Our results show that in high-water and high-salt habitats, photosynthesis is affected by &ldquo;stomata restriction,&rdquo; while in other habitats, photosynthesis is mainly affected by &ldquo;non-stomata restriction.&rdquo; In addition, when the soil conditions were good, Haloxylon ammodendron chose leaf construction featuring high specific leaf area, while when the soil conditions were worse, it chose an opposite leaf construction model to ensure the optimal allocation of carbon assimilation products in heterogeneous habitats. This study will deepen our understanding of the trade-off strategy between the accumulation and distribution of plant photosynthate in special habitats in arid areas. The results are of theoretical value for analysis of the ecological adaptation mechanisms of plants in arid desert areas

Effects of Water Control and Nitrogen Addition on Functional Traits and Rhizosphere Microbial Community Diversity of <i>Haloxylon ammodendron</i> Seedlings

Water and nitrogen sources have always been the primary limiting factors for vegetation growth in arid and semi-arid regions and play an important role in the physiological ecology of vegetation. In this work, we studied the effects of water deficit and nitrogen addition on the physiological traits and rhizosphere bacterial microbial community of Haloxylon ammodendron seedlings in sterilized and non-sterilized soil habitats. A pot experiment was conducted to control the water and nitrogen sources of H. ammodendron seedlings. The water deficit treatment was divided into two groups based on gradient: a normal water group (CK, 70% field water holding capacity) and water deficit group (D, 30% field water holding capacity). The nitrogen addition treatment was divided into a no addition group (CK, 2.8 mg·kg−1) and addition group (N, 22.4 mg·kg−1). At the end of the growing season, the biochemical indexes of H. ammodendron seedlings were measured, and the rhizosphere soil was subjected to 16S rDNA-high-throughput sequencing to determine the rhizosphere bacterial community composition of H. ammodendron seedlings under different treatments. The results showed that the root-to-crown ratio of H. ammodendron seedlings increased significantly (p H. ammodendron seedlings preferred to allocate biological carbon to the lower part of the ground. In contrast, plant height and root length were significantly lower (p H. ammodendron seedlings and nitrogen addition mitigated the effect of water deficit on the growth of H. ammodendron seedlings. Under sterilized soil conditions, both water deficit and nitrogen addition significantly increased the abundance and diversity of bacterial communities in H. ammodendron seedlings (p H. ammodendron seedlings were affected by water deficit and allocated greater quantities of biomass to the underground part, especially in the non-sterile microbial environment; different initial soil conditions resulted in divergent responses of rhizosphere bacterial communities to water deficit and nitrogen addition. Under different initial soil conditions, the same water deficit and nitrogen addition treatment will lead to the development of distinct differences in rhizosphere bacterial community composition

Characteristics and driving mechanisms of species beta diversity in desert plant communities.

Species dissimilarity (beta diversity) primarily reflects the spatio-temporal changes in the species composition of a plant community. The correlations between β diversity and environmental factors and spatial distance can be used to explain the magnitudes of environmental filtering and dispersal. However, little is known about the relative roles and importance of neutral and niche-related factors in the assemblage of plant communities with different life forms in deserts. We found that in desert ecosystems, the β diversity of herbaceous plants was the highest, followed by that of shrubs and trees. The changes in the β diversity of herbs and shrubs had stronger correlations with the environment, indicating that community aggregation was strongly affected by niche processes. The soil water content and salt content were the key environmental factors affecting species distributions of the herb and shrub layers, respectively. Spatial distance explained a larger amount of the variation in tree composition, indicating that dispersal limitation was the main factor affecting the construction of the tree layer community. The results suggest that different life forms may determine the association between organisms and the environment. These findings suggest that the spatial patterns of plant community species in the Ebinur Lake desert ecosystem are the result of the combined effects of environmental filtering and dispersal limitation