Micromorphological Features of Old Cultivated and Modern Soils in Guanzhong Areas, Shaanxi Province, China

Using the data obtained from the LGT soil profile, this article attempts to illustrate the process of modem soil formation in the Guanzhong areas and its micromorphological features. The micromorphology is observed under a petrographic microscope, and its image is quantitatively measured by LEICAL Qwin 2.6 software. Micromorphological observations of the thin sections show that the assemblage of minerals in different horizons is very similar, which is mainly composed of Q and P1. However, there are obvious differences in C/F15μm ratio, mineral content, and coarse features. The pedofeatures is mainly composed of clay, calcite, and amorphous Fe. Ap horizon is characterized by abundant needleshaped secondary calcite, secondary clay, and earthworm fecal pellet. BC horizon is characterized by a large quantity of secondary calcite with various shapes. Bt1and Bt2 horizons are characterized by abundant clay hypocoatings and a small quantity of secondary calcite. All the results of this research suggest that Earth-cumulic Orthic Anthrosols consist of both the upper Ap horizon, which cause loessal dung and eolian dust deposition, and cultivation occurs simultaneously during the process of Ap horizon-formation, and the lower BC horizon, which is aeolian sedimentary at the time of relative aridity during late Holocene.

Comparison of Micromorphological Features of Two Agricultural Cultivated Soils in Guanzhong Areas, Shaanxi Province, China

By comparing micromorphological features of irrigated and non-irrigated soils in Guanzhong areas, China, this paper tries to illustrate the influences of farming management methods on the soil-forming process. The micromorphology was observed under a petrographic microscope and its image was quantificationally measured by Nikon NISBR 2.2 software. Both irrigated and non-irrigated soils have the same soil profile pattern, Ap1- AP2- BC, but the former has a more obvious profile dissimilation. The minerals assemblage of soil profiles A and B are very similar, which is mainly composed of Q and P1. Compared with non-irrigated soil, grains of irrigated soil remarkably decrease in length, area, eqdiameter, perimeter, elongation, roundness, and C/F10μm ratio; voids are characterized by more regular void shape and more smooth void wall; there is more abundant residual clay and small amount of illuvial clay. All results in this study suggest that the farming management method has influences on soil profile dissimilation and micromorphology. Agricultural irrigation could strengthen the degree of weathering, make smaller and rounder soil grains, cause a significant increase of residual clay and appearance of illuvial clay. But no significant change has been observed in the minerals assemblage of coarse grains.

Three-dimensional crustal deformation before and after the Wenchuan earthquake in Guanzhong and adjacent regions

The recent plethora of GPS observations compensates for the 20-year-old lack in vertical displacement data for the Guanzhong region. The 2001—2007 three-dimensional（3D） crustal deformation data suggest regional movement with a horizontal velocity of 3—7 mm/a,predominantly from SSE in the west to SE in the east, and vertical inherited movement with velocity of -7 mm/a to 4 mm/a. After the Wenchuan earthquake, the GPS data suggest that the effect of the earthquake on the regional deformation is greater in the west than the east.The horizontal displacement increased during 2007—2008; however, the reverse was observed in 2008—2009. The vertical displacement in the western part of the region increased in 2008 and has been gradually returning to normal since 2009; however, in the eastern part,the effect of the earthquake remains.

A Preliminary Study on the Main Ridge Decoration of Buildings in Yuan,Ming,and Qing Dynasties in Guanzhong Area

The function of roof ridge ornament is irreplaceable in the facade modeling of traditional Chinese architecture.Taking the ornament in the Ming and Qing Dynasties in Guanzhong area as an example,this paper summarizes and analyzes the appearance characteristics,and internal cultural connotation of the ornament that is currently present in the Guanzhong area from the aspects of its decorative content,color,and grade indication.Further,make relevant discussions,hoping to supplement the research of ancient ornament.

Phenological records in Guanzhong Area in central China between 600 and 902 AD as proxy for winter half-year temperature reconstruction

Phenological data obtained from historical documents constitute highly important ecological evidence for the pre-instrumental period, and can be used in analyzing climatic change in history. In this study, 87 phenological records about seasonality of non-biological events （e.g., first frost date）, agriculture and ornamental plants （e.g., first flowering date） over 77 years were extracted from historical documents from the Sui and Tang dynasties in China to reconstruct the winter half-year （from October to next April） temperatures in the Guanzhong Area （located in central China） from 600 to 902 AD. Transfer functions between temperature and phenophases with significant correlations were established by using modem observation data. Temperatures from the study period were reconstructed by applying the transfer functions to historical phenological data. The reconstruction indicates that the winter half-year temperatures during 600-902 AD were 0.23~C higher than the reference period （1961-1990）. The temperature changed with two distinct stages. During the 600s-800s, temperatures were approxi- mately 0.38~C higher than at present but then temperatures decreased in the subsequent period （800-902 AD）. These results are similar to ones from previous studies on the mean temperature and the divisions between warm and cold periods during the study period, though differences were found in the degree of warmness/coldness. This reconstruction provides a valuable contribution to a better understanding of climatic variability during the Sui and Tang dynasties in China.

Spatio-temporal analysis of cropland change in the Guanzhong area, China, from 1650 to 2016

As one of the most critical impact factors of global change,historical land-use change is an indispensable input in climate and environment simulations.To better understand the cropland change in the Guanzhong area,gazetteers,statistics,and survey data were collected as data sources.Methods of registered tax-paying cropland data collection,selection of time points,and data interpolation and calibration were used to reconstruct changes in the cropland area.The cropland area data at the county level were allocated to 1 km×1 km grid cells.The total cropland area in the Guanzhong area was influenced by changes in population,wars,natural disasters,and land-use types,and it fluctuated from 1650 to 2016.From 1780 to 1830,the cropland expanded in the northern and western parts of Guanzhong area,and the cropland in the north of Qinling Mountains increased slightly.The spatial pattern of cropland reached its maximum range in 1980,and the cropland area declined in the whole study area,especially in the cities of Xi’an and Xianyang in 2016.The comparison between HYDE 3.2 and the data obtained in this study showed that the grid cells of HYDE 3.2 exhibit lower values of cropland area fractions in the Guanzhong Basin and higher values in high-altitude areas around the Guanzhong Basin as compared to those in this study.