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Islands, which provide multiple ecosystem services, are subject to increasing urbanization pressure due to the ongoing marine development, especially in developing countries. Insights into the island urbanization mechanism and its ecological consequences are essential to sustainable development. In the present paper, the satellite images, nighttime lights, and topographic data were integrated to characterize the spatially explicit urbanization process and mechanism during 1995–2011 in the Zhoushan Island, East China. Furthermore, the corresponding spatially explicit changes in ecosystem services, including net primary productivity (NPP), carbon sequestration and oxygen production (CSOP), nutrient cycling, crop production, and habitat quality, were quantified based on the Carnegie–Ames–Stanford Approach (CASA) and Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) models. The results showed that the Zhoushan Island had experienced a rapid urbanization over the years, with significant urban encroachment on the farmland and tidal flat. Moreover, the urban land expansion was positively correlated with that of the nighttime lights and negatively correlated with the elevation, slope, and the distance to shoreline. These indicated that the urban expansion was resulted from the enhancement of socioeconomic activities, and concentrated in the near-shore areas with low altitude and gentle slope. The urban encroachment on other land use types resulted in a decrease of 3.4 Gg C a−1 NPP, 8.7 Gg a−1 CSOP, 13.2 Gg a−1 nutrient cycling, and 12.3 t a−1 crop production, respectively. In addition, the habitat quality in 11% area of this island degraded substantially. Therefore, to achieve sustainable development of islands, it is urgent to implement more stringent policies, such as island spatial regulation, environmental impact assessment, intensive land use, and urban greening, etc. 相似文献
3.
Michael Kleyer 《植被学杂志》1999,10(5):697-708
Abstract. In this study, plant functional types are understood as groups of plants with similar biological traits displaying significant optima or maxima on a gradient plane of resource supply and disturbance intensity. The biological traits refer to expansion, vegetative regeneration, generative reproduction, dispersal and seed bank longevity. 129 vegetation samples were taken in an agricultural landscape in southwestern Germany, covering a wide range of terrestrial vegetation types – but with the exception of forests and wetlands. For each site, also soil data were recorded. Mean daily soil moisture was estimated with a simple model. Soil moisture, balanced nitrogen supply and available phosphorus were combined into a factor ‘resource supply’. In addition, disturbance intensity was estimated for each site. This factor was based on (1) frequency of disturbance, (2) disturbance depth below or above the soil surface, and (3) proportion of the area affected by a discrete disturbance event. 30 plant groups with similar biological characteristics resulted from a cluster analysis, based on a compilation of 19 biological traits for a regional species pool. Logistic regression on a gradient plane of disturbance intensity and resource supply yielded response curves for 28 groups. The dependent variable was defined as the probability of encountering all members of a group in a sample. 17 groups display a significant response curve on the gradient plane. Plants with a potential for long- range dispersal are concentrated on sites with low or high disturbance intensities (e.g. fallow land, fields, lawns). On sites with medium disturbance intensity (e.g. meadows) and low to medium resource supply, small-range dispersal predominates. There are no distinct trends concerning seed bank longevity. The potential for vertical and lateral expansion increases with decreasing disturbance intensity. Only at medium disturbance intensities does vertical expansion correlate positively with resource supply. Rapid detachment of daughter individuals occurs more often on productive sites than on less productive sites. Diversity of groups with similar biological traits is highest on sites with medium disturbance intensities. 相似文献
4.
Overconfidence and underconfidence: When and why people underestimate (and overestimate) the competition 总被引:5,自引:0,他引:5
Don A. Moore Daylian M. Cain 《Organizational behavior and human decision processes》2007,103(2):197-213
It is commonly held that people believe themselves to be better than others, especially for outcomes under their control. However, such overconfidence is not universal. This paper presents evidence showing that people believe that they are below average on skill-based tasks that are difficult. A simple Bayesian explanation can account for these effects and for their robustness: On skill-based tasks, people generally have better information about themselves than about others, so their beliefs about others’ performances tend to be more regressive (thus less extreme) than their beliefs about their own performances. This explanation is tested in two experiments that examine these effects’ robustness to experience, feedback, and market forces. The discussion explores the implications for strategic planning in general and entrepreneurial entry in particular. 相似文献
5.
免疫细胞浸润对癌症的诊断与预后有着重要意义。文中收集TCGA数据库已收录的非小细胞肺癌肿瘤与正常组织基因表达数据,利用CIBERSORT工具得到22种免疫细胞占比来评估免疫细胞浸润情况。以22种免疫细胞占比为特征,用机器学习方法构建了非小细胞肺癌肿瘤与正常组织的分类模型,其中随机森林方法构建的模型分类效果AUC=0.987、敏感性0.98及特异性0.84。并且用随机森林方法构建的肺腺癌和肺鳞癌肿瘤组织分类模型效果AUC=0.827、敏感性0.75及特异性0.77。用LASSO回归筛选22种免疫细胞特征,保留8种强相关特征组成的免疫细胞评分结合临床特征构建了非小细胞肺癌预后模型。经评估及验证,预后模型C-index=0.71并且3年和5年的校准曲线拟合良好,可以对预后风险度进行准确预测。本研究基于免疫细胞浸润所构建的分类模型与预后模型,旨在对非小细胞肺癌的诊断与预后研究提供新的策略。 相似文献
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9.
Factors influencing the spatial distribution of forest plant species in hedgerows of North-western Germany 总被引:2,自引:0,他引:2
In North-western Germany woodland fragmentation has caused a decline in many forest plant species. Hedgerows partly offer
a similar environment as forests and have been identified as potential habitats for forest plants in various studies from
North America and Western Europe. The objective of this study was to examine whether this applies also to Central Europe and
which variables affect the spatial distribution and abundance of forest plant species in hedgerows on a local scale. Three
hedgerow networks north of the city of Bremen, Germany, were selected as study areas and divided into totally 515 hedgerow
segments. In each segment we recorded all vascular plants and a large number of explanatory variables relating to structure,
spatial configuration, environment and management. Averaged across species there was a predominant effect of environmental
factors on the occurrence of forest species in the hedgerows, followed by spatial configuration and management. Hedgerow structure
was found to be less important. In general, forest species were favored by low nutrient and light availability as well as
high connectivity with other hedgerows or forest; they avoided hedgerows with a west-easterly orientation and an adjacent
land use in the form of fields or grasslands. Forest species found and not found in hedgerows did not differ in their environmental
preferences or life history traits. The number of threatened forest species in the hedgerows, however, was lower than expected
with respect to their overall proportion to the total number of forest species in the region. 相似文献
10.
基于低压氧弹燃烧法研究了充氧压力分别为0.6MPa和0.9MPa时两种无灰型柴油添加剂不同配比对助燃性能的影响。采用均匀实验设计和Matlab回归优化的方法,得到复配体系的最优配方,并对其进行了验证。结果表明,由Matlab回归分析得到的完全二次回归模型最理想,0.6MPa时由该模型得到的最优配方为:添加剂A和B的质量分数分别是0.300‰和0.700‰,并通过实验验证得到的发热量达到最大,变化率为8.697%。0.9MPa时,结合直观分析和回归分析,得到与实际相符的最优配方:添加剂A和B的质量分数分别是0.600‰和0.900‰,此时发热量皮化率为4.453%。 相似文献