The changing patterns of cropland conversion to built-up land in China from 1987 to 2010

Over the past few decades, built-up land in China has increasingly expanded with rapid urbanization, industrialization and rural settlements construction. The expansions encroached upon a large amount of cropland, placing great challenges on national food security. Although the impacts of urban expansion on cropland have been intensively illustrated, few attentions have been paid to differentiating the effects of growing urban areas, rural settlements, and industrial/transportation land. To fill this gap and offer comprehensive implications on framing policies for cropland protection, this study investigates and compares the spatio- temporal patterns of cropland conversion to urban areas, rural settlements, and industrial/ transportation land from 1987 to 2010, based on land use maps interpreted from remote sensing imagery. Five indicators were developed to analyze the impacts of built-up land expansion on cropland in China. We find that 42,822 km² of cropland were converted into built-up land in China, accounting for 43.8% of total cropland loss during 1987–2010. Urban growth showed a greater impact on cropland loss than the expansion of rural settlements and the expansion of industrial/transportation land after 2000. The contribution of rural settlement expansion decreased; however, rural settlement saw the highest percentage of traditional cropland loss which is generally in high quality. The contribution of industrial/transportation land expansion increased dramatically and was mainly distributed in major food production regions. These changes were closely related to the economic restructuring, urban-rural transformation and government policies in China. Future cropland conservation should focus on not only finding a reasonable urbanization mode, but also solving the “hollowing village” problem and balancing the industrial transformations.     

A cyber-enabled spatial decision support system to inventory Mangroves in Mozambique: coupling scientific workflows and cloud computing

Mangroves are an important terrestrial carbon reservoir with numerous ecosystem services. Yet, it is difficult to inventory mangroves because of their low accessibility. A sampling approach that produces accurate assessment while maximizing logistical integrity of inventory operation is often required. Spatial decision support systems (SDSSs) provide support for integrating such a sampling design of fieldwork with operational considerations and evaluation of alternative scenarios. However, this fieldwork design driven by SDSS is often computationally intensive and repetitive. In this study, we develop a cyber-enabled SDSS framework to facilitate the computationally challenging fieldwork design that requires the efficacious selection of base camps and plots for the inventory of mangroves. Our study area is the Zambezi River Delta, Mozambique. Cyber-enabled capabilities, including scientific workflows and cloud computing, are integrated with the SDSS. Scientific workflows enable the automation of data and modeling tasks in the SDSS. Cloud computing offers on-demand computational support for interoperation among stakeholders for collaborative scenario evaluation for the fieldwork design of mangrove inventory. Further, this framework allows for harnessing high-performance computing capabilities for accelerating the fieldwork design. The cyber-enabled framework provides significant merits in terms of effective coordination among science and logistical teams, assurance of meeting inventory objectives, and an objective basis to collectively and efficaciously evaluate alternative scenarios.     

“特色全球城市”目标下的新加坡河滨水空间再生与启示

本文尝试在新加坡经济发展与转型的基本背景下,理解新加坡建设“特色全球城市”的目标;探讨在该目标的驱动下曾一度衰落的新加坡河滨河区如何实现空间功能的转变与再生,成为兼具社会开放性与包容性、全球化与本土化的空间载体,并推动新加坡城市的可持续发展与“特色全球城市”目标的实现;最后总结了其对于“建设美丽中国”目标下中国城市滨水空间开发的借鉴与启示。     

ITS sequence analysis of Artemisia halodendron in different habitat gradients

The aim of the present study is to investigate the difference between ITS sequences of Artemisia halodendron Turcz. from different habitat gradients in Horqin Sandy Land, with Artemisia depauperata Krasch. selected as the outgroup. Results indicate that the total length of A. halodendron ITS is 696 bp, the lengths of unaligned ITS-1 and ITS-2 sequences varied from 253 to 256 bp and 264 to 269 bp, respectively, and GC content of ITS-1 and ITS-2 sequences ranged from 54.02% to 54.77% and 56.75% to 58.64%, respectively. This indicates a high difference of length and composition of sequences in ITS-1 than ITS-2. The genetic identity between ITS sequences of A. halodendron from nine populations ranged from 85.7% to 99.7% which indicates some genetic differentiation between sequences. In the maximum parsimony (MP) tree, most ITS sequences from A. halodendron show two major clades: Clade I and Clade II, with Clade II older than Clade I. The order is subp4 → subp1 → subp2 → subp3 → subp8 → subp6 → subp7 → subp9 → subp5, and corresponding habitat order is: inter-dune lowlands → semi-mobile dune → mobile dune → semi-fixed dune → fixed dune. This indicates a close relation between the evolutionary processes of A. halodendron and desertification forming processes and ecological restoration processes of Horqin Sandy Land.     

DISTRIBUTION AND POPULATION DYNAMICS OF PARACALANUS PARVUS,PRACALANUS CRASSIROSTRIS,AND ACARTIA BIFILOSA（COPEPODA,CALANOIDA）IN THE BOHAI SEA

Paracalanus parvus,Paracalanus crassirostris,and Acartia bifilosa are dominant and widely distributed in the Bohai Sea,and comprise an important part of zooplankton in terms of biomass as well as production rate.In order to understand their seasonal distribution and population dynamics,their stage-specific abundance in different months of the year were analyzed based on the never analyzed yet samples collected in 1959.The three species showed clear and remarkable seasonal variation in abundance,which maximized in spring and summer,when they formed high biomass patches or concentrations in the nearshore area.For Paracalanus parvus,two peaks were observed in the annual circle,one in June and the other in September,For Paracalanus crassirostris,one peak occurred in summer and a small one in December.The seasonal pattern of Acartia bifilosa was different in different regions.In Bohai Bay it had a two-peak pattern,with the first large peak occurring in May and the second one in October.In Laizhou Bay,a winter peak in December and January could be observed besides the spring one.The number of generations during the reproductive season for the three species was estimated based on the annual cycle in abundance and ambient temperature.     

FRACTAL ANALYSIS APPLIED TO SPATIAL STRUCTURE OF CHINA＇S VEGETATION

Based on the fractal theory, the spatial structure of China＇s vegetation has been analyzed quantitatively in this paper. Some conclusions are drawn as the following. 1） The relationships between size and frequency of patch area and patch shape index exist objectively for China＇s vegetation. 2） The relationships between perimeter and area exist objectively for China＇s vegetation. 3） The fractal dimension of evergreen needleleaf forests on mountains in subtropical and tropical zones is the largest, while the smallest for deciduous broadleafand evergreen needleleaf mixed forests in temperate zone, reflecting the most complex spatial structure for evergreen needleleaf forests on mountains in subtropical and tropical zones and the simplest for deciduous broadleaf and evergreen needleleaf mixed forests in temperate zone. 4） The fractal dimensions of China＇s vegetation types tend to decrease from thc subtropics to both sides. 5） The stability of spatial structure of deciduous broadleaf and evergreen needleleaf mixed forests in temperate zone is the largest, while the smallest for double-cropping rice, or double-cropping rice and temperate-like grain, and tropical evergreen economic tree plantations and orchards, reflecting the steadiest for deciduous broadleaf and evergreen needleleaf mixed forests in temperate zone and the most unstable for double-cropping rice, or double-cropping rice and temperate-like grain, and tropical evergreen economic tree plantations and orchards in spatial structure. 6） The stability of spatial structure of China＇s vegetation tends to decrease from the temperate zone to both sides, it is significantly pertinent to understand the formation, evolution, dynamics and complexity rule of ecosystem of vegetation.     

中国冬季积雪特征及欧亚大陆积雪对中国气候影响

该文首先回顾了有关中国冬季积雪的研究进展,包括中国冬季积雪的空间分布气候特征以及季节、年际和年代际变化,中国冬季降雪特征,气象因子对中国冬季积雪水量平衡的影响,外强迫和大气环流系统在积雪形成中的作用等。冬春季欧亚大陆积雪对同期和后期中国气候影响的相关研究说明与欧亚大陆积雪异常相关联的中国气候异常以及积雪通过改变土壤湿度、表面温度和辐射分布,引起大气环流异常,进而对中国气候产生影响的物理过程。应用美国环境预测中心 (NCEP) 第2版气候预测系统 (CFSv2) 的回报试验结果,对CFSv2在欧亚大陆积雪变化及其与中国气候关系的可预报性方面的分析表明,CFSv2能够较好地回报出春季欧亚积雪的年际和年代际变异及其与中国夏季降水之间的联系。文章最后提出了在积雪及其气候效应研究方面一些有待解决的问题。     

Vertical distribution of soil moisture and surface sandy soil wind erosion for different types of sand dune on the southeastern margin of the Mu Us Sandy Land, China

Soil moisture is a critical state affecting a variety of land surface and subsurface processes. We report investigation results of the factors controlling vertical variation of soil moisture and sand transport rate of three types of dunes on the southeastern margin of the Mu Us Sandy Land. Samples were taken from holes drilled to a depth of 4 m at different topographic sites on the dunes, and were analyzed for soil moisture, grain-size distribution and surface sediment discharge. The results show that: (1) The average soil moisture varies in different types of dunes, with the following sequences ordered from highest to lowest: in the shrubs-covered dunes and the trees-covered dunes the sequence is from inter-dunes lowland to windward slope to leeward slope. The average moisture in the bare-migratory sand dunes is sequenced from inter-dunes lowland to leeward slope to windward slope. (2) Vegetation form and surface coverage affect the range of soil moisture of different types of dunes in the same topographic position. The coefficient of variation of soil moisture for shrubs-covered dunes is higher than that of other types of dune. (3) The effect of shrubs on dune soil moisture is explained in terms of the greater ability of shrubs to trap fine-grained atmospheric dust and hold moisture. (4) The estimated sand transport rates over sand dunes with sparse shrubs are less than those over bare-migratory dunes or sand dunes with sparse trees, indicating that shrubs are more effective in inhibiting wind erosion in the sandy land area.     

Problems related to single gully debris flow assessment models

Natural Hazards - In recent years, various models for single gully debris flow assessment have been proposed. Due to various factors affecting the mechanisms of debris flows, these models face many...     

Robust Feature Extraction for Geochemical Anomaly Recognition Using a Stacked Convolutional Denoising Autoencoder

Mathematical Geosciences - Deep neural networks perform very well in learning high-level representations in support of multivariate geochemical anomaly recognition. Geochemical exploration data...