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1. chinaXiv:202110.00020 [pdf]

Response of C:N:P in the plant-soil system and stoichiometric homeostasis of Nitraria tangutorum leaves in the oasis-desert ecotone, Northwest China

WEI Yajuan; DANG Xiaohong; WANG Ji; GAO Junliang; GAO Yan
Subjects: Geosciences >> Geography

Nitraria tangutorum nebkhas are widely distributed in the arid and semi-arid desert areas of China. The formation and development of N. tangutorum nebkhas are the result of the interaction between vegetation and the surrounding environment in the process of community succession. Different successional stages of N. tangutorum nebkhas result in differences in the community structure and composition, thereby strongly affecting the distribution of soil nutrients and ecosystem stability. However, the ecological stoichiometry of N. tangutorum nebkhas in different successional stages remains poorly understood. Understanding the stoichiometric homeostasis of N. tangutorum could provide insights into its adaptability to the arid and semi-arid desert environments. Therefore, we analyzed the stoichiometric characteristics of N. tangutorum in four successional stages, i.e., rudimental, developing, stabilizing, and degrading stages using a homeostasis model in an oasis-desert ecotone of Northwest China. The results showed that soil organic carbon (SOC), total nitrogen (TN), and total phosphorus (TP) contents and their ratios in the 0–100 cm soil depth were significantly lower than the averages at regional and global scales and were weakly influenced by successional stages in the oasis-desert ecotone. TN and TP contents and C:N:P in the soil showed similar trends. Total carbon (TC) and TN contents in leaves were 450.69–481.07 and 19.72–29.35 g/kg, respectively, indicating that leaves of N. tangutorum shrubs had a high storage capacity for C and N. Leaf TC and TN contents and N:P ratio increased from the rudimental stage to the stabilizing stage and then decreased in the degrading stage, while the reverse trend was found for leaf C:N. Leaf TP content decreased from the rudimental stage to the degrading stage and changed significantly in late successional stages. N:P ratio was above the theoretical limit of 14, indicating that the growth of N. tangutorum shrubs was limited by P during successional stages. Leaf N, P, and N:P homeostasis in four successional stages was identified as ''strictly homeostasis''. Redundancy analysis (RDA) revealed that soil acidity (pH) and the maximum water holding capacity were the main factors affecting C:N:P stoichiometric characteristics in N. tangutorum leaves. Our study demonstrated that N. tangutorum with a high degree of stoichiometric homeostasis could better cope with the arid desert environment.

submitted time 2021-10-11 From cooperative journals:《Journal of Arid Land》 Hits2447Downloads69 Comment 0

2. chinaXiv:202107.00020 [pdf]

An arthropod community beyond the dry limit of plant life

Benjamin DAVIDSON; Elli GRONER
Subjects: Geosciences >> Geography

Water availability, which enables plant growth and animal activity, regulates dryland ecosystem function. In hyper-arid ecosystems, rain cannot support vascular plant growth. Therefore, hyper-arid vegetation is restricted to the lower topography, where runoff accumulates. Typically, food resources originating from areas of dense vegetation are dispersed across the desert floor, enabling animal life in areas lacking vascular plant growth. However, certain regions, such as the hyper-arid upper topography, may be devoid of plant-derived food resources. The present study examined arthropod activity in the upper topography of a hyper-arid desert, in comparison with arthropod activity in the lower topography. Pitfall traps were utilized to compare arthropod activity along unvegetated ridges with activity in parallel, vegetated riverbeds. Surprisingly, the study revealed dense arthropod communities in the barren upper topography. Arthropods collected in the upper topography represented 26% of total arthropod abundance. In addition, the overlap between arthropod identity in the ridges and wadis (i.e., riverbeds) was low, and certain arthropods were strongly affiliated with the ridges. The upper topographic communities included high numbers of silverfish (Zygentoma: Lepismatidae), malachite beetles (Psiloderes), and predatory mites (Acari: Anystidae), and these arthropods were present at various life stages. It remains unclear how arthropod communities can persist in the unvegetated upper topography of the hyper-arid study area. These results raise the possibility that other food sources, independent from vascular plants, may play a significant role in the life history of hyper-arid arthropods.

submitted time 2021-07-23 From cooperative journals:《Journal of Arid Land》 Hits1161Downloads313 Comment 0

3. chinaXiv:202005.00094 [pdf]

Change features of time-series climate variables from 1962 to 2016 in Inner Mongolia, China

XU Lili; YU Guangming; ZHANG Wenjie; TU Zhenfa; TAN Wenxia
Subjects: Biology >> Botany >> Applied botany

Detecting change features of climate variables in arid/semi-arid areas is essential for understanding related climate change patterns and the driving and evolution mechanism between climate and arid/semi-arid ecosystems. This paper takes Inner Mongolia of China, a unique arid/semi-arid ecosystem, as the study area. We first detected trend features of climate variables using the linear trend analysis method and then detected their trend-shift features using the breaks for additive seasonal and trend method based on the time-series of monthly precipitation and monthly mean temperature datasets from 1962 to 2016. We analyzed the different change features of precipitation and temperature on a regional scale and in different ecological zones to discover the spatial heterogeneity of change features. The results showed that Inner Mongolia has become warmer-wetter during the past 54 years. The regional annual mean temperature increased 0.4°C per decade with a change rate of 56.2%. The regional annual precipitation increased 0.07 mm per decade with a slightly change rate of about 1.7%, but the trend was not statistically significant. The warmer trend was contributed by the same positive trend in each season, while the wetter trend was contributed by the negative trend of the summer precipitation and the positive trend of the other three seasons. The regional monthly precipitation series had a trend-shift pattern with a structural breakpoint in the year 1999, while the regional monthly mean temperature series showed an increasing trend without a periodical trend-shift. After the year 2000, the warmer-wetter trend of the climate in Inner Mongolia was accelerated. The late 20th century was a key period, because the acceleration of the wetter trend in some local zones (I and II) and the alleviation of the warmer trend in some local zones (VII, VIII and IX) occurred simultaneously. Moreover, the change features had a strong spatial heterogeneity, the southeastern and southwestern of Inner Mongolia went through a warmer-drier trend compared with the other areas. The spatio-temporal heterogeneity of the climate change features is a necessary background for various types of research, such as regional climate change, the evolution of arid/semi-arid ecosystems, and the interaction mechanisms between climate and arid/semi-arid ecosystems based on earth-system models in Inner Mongolia.

submitted time 2020-05-31 From cooperative journals:《Journal of Arid Land》 Hits9374Downloads1187 Comment 0

4. chinaXiv:202004.00046 [pdf]

Change features of time-series climate variables from 1962 to 2016 in Inner Mongolia, China

XU Lili; YU Guangming; ZHANG Wenjie; TU Zhenfa; TAN Wenxia
Subjects: Environmental Sciences, Resource Sciences >> Basic Disciplines of Environmental Science and Technology

Detecting change features of climate variables in arid/semi-arid areas is essential for understanding related climate change patterns and the driving and evolution mechanism between climate and arid/semi-arid ecosystems. This paper takes Inner Mongolia of China, a unique arid/semi-arid ecosystem, as the study area. We first detected trend features of climate variables using the linear trend analysis method and then detected their trend-shift features using the breaks for additive seasonal and trend method based on the time-series of monthly precipitation and monthly mean temperature datasets from 1962 to 2016. We analyzed the different change features of precipitation and temperature on a regional scale and in different ecological zones to discover the spatial heterogeneity of change features. The results showed that Inner Mongolia has become warmer-wetter during the past 54 years. The regional annual mean temperature increased 0.4°C per decade with a change rate of 56.2%. The regional annual precipitation increased 0.07 mm per decade with a slightly change rate of about 1.7%, but the trend was not statistically significant. The warmer trend was contributed by the same positive trend in each season, while the wetter trend was contributed by the negative trend of the summer precipitation and the positive trend of the other three seasons. The regional monthly precipitation series had a trend-shift pattern with a structural breakpoint in the year 1999, while the regional monthly mean temperature series showed an increasing trend without a periodical trend-shift. After the year 2000, the warmer-wetter trend of the climate in Inner Mongolia was accelerated. The late 20th century was a key period, because the acceleration of the wetter trend in some local zones (I and II) and the alleviation of the warmer trend in some local zones (VII, VIII and IX) occurred simultaneously. Moreover, the change features had a strong spatial heterogeneity, the southeastern and southwestern of Inner Mongolia went through a warmer-drier trend compared with the other areas. The spatio-temporal heterogeneity of the climate change features is a necessary background for various types of research, such as regional climate change, the evolution of arid/semi-arid ecosystems, and the interaction mechanisms between climate and arid/semi-arid ecosystems based on earth-system models in Inner Mongolia.

submitted time 2020-04-23 From cooperative journals:《Journal of Arid Land》 Hits1358Downloads689 Comment 0

5. chinaXiv:201906.00043 [pdf]

Low soil temperature reducing the yield of drip irrigated rice in arid area by influencing anther development and pollination

ZHANG Jun
Subjects: Biology >> Botany

Drip irrigation can produce high rice yields with significant water savings; therefore, it is widely used in arid area water-scarce northern China. However, high-frequency irrigation of drip irrigation with low temperature well water leads to low root zone temperature and significantly reduce the rice yield compared to normal temperature water irrigated rice, for example, reservoir water. The main purpose of this paper is to investigate the effects of low soil temperature on the yield reduction of drip irrigated rice in the spike differentiation stage. The experiment set the soil temperatures at 18°C, 24°C and 30°C under two irrigation methods (flood and drip irrigation), respectively. The results showed that, at the 30°C soil temperature, drip irrigation increased total root length by 53% but reduced root water conductivity by 9% compared with flood irrigation. Drip irrigation also increased leaf abscisic acid and proline concentrations by 13% and 5%, respectively. These results indicated that drip irrigated rice was under mild water stress. In the 18°C soil temperature, drip irrigation reduced hydraulic conductivity by 58%, leaf water potential by 40% and leaf net photosynthesis by 25% compared with flood irrigation. The starch concentration in male gametes was also 30% less in the drip irrigation treatment than in the flood irrigation treatment at soil temperature 18°C. Therefore, the main reason for the yield reduction of drip irrigated rice was that the low temperature aggravates the physiological drought of rice and leads to the decrease of starch content in male gametes and low pollination fertilization rate. Low temperature aggravates physiological water deficit in drip irrigated rice and leads to lower starch content in male gametes and low pollination fertilization rate, which is the main reason for the reduced yield of drip irrigated rice. Overall, the results indicated that the low soil temperatures aggravated the water stress that rice was under in the drip irrigated environment, causing declines both in the starch content of male gametes and in pollination rate. Low temperature will ultimately affect the rice yield under drip irrigation.

submitted time 2019-06-20 From cooperative journals:《Journal of Arid Land》 Hits7120Downloads1040 Comment 0

6. chinaXiv:201810.00182 [pdf]

Effects of combined drip irrigation and sub-surface pipe drainage on water and salt transport of saline-alkali soil in Xinjiang, China

HENG Tong; LIAO Renkuan; WANG Zhenhua; WU Wenyong; LI Wenhao; ZHANG Jinzhu
Subjects: Geosciences >> History of Geosciences

Developing effective irrigation and drainage strategies to improve the quality of saline-alkali soil is vital for enhancing agricultural production and increasing economic returns. In this study, we explored how irrigation and drainage modes (flood irrigation, drip irrigation, and sub-surface pipe drainage under drip irrigation) improve the saline-alkali soil in Xinjiang, China. We aimed to study the transport characteristics of soil water and salt under different irrigation and drainage modes, and analyze the effects of the combination of irrigation and drainage on soil salt leaching, as well as its impacts on the growth of oil sunflower. Our results show that sub-surface pipe drainage under drip irrigation significantly reduced the soil salt content and soil water content at the 0–200 cm soil depth. Under sub-surface pipe drainage combined with drip irrigation, the mean soil salt content was reduced to below 10 g/kg after the second irrigation, and the soil salt content decreased as sub-surface pipe distance decreased. The mean soil salt content of flood irrigation exceeded 25 g/kg, and the mean soil desalination efficiency was 3.28%, which was lower than that of drip irrigation. The mean soil desalination rate under drip irrigation and sub-surface pipe drainage under drip irrigation was 19.30% and 58.12%, respectively. After sub-surface drainage regulation under drip irrigation, the germination percentage of oil sunflower seedlings was increased to more than 50%, which further confirmed that combined drip irrigation and sub-surface pipe drainage is very effective in improving the quality of saline-alkali soil and increasing the productivity of agricultural crops.

submitted time 2018-10-29 From cooperative journals:《Journal of Arid Land》 Hits4363Downloads1338 Comment 0

7. chinaXiv:201807.00030 [pdf]

Toxic metal enrichment characteristics and sources of arid urban surface soil in Yinchuan City, China

ZHANG, Mingxin; LU, Xinwei; SHI, Dongqi; PAN, Huiyun
Subjects: Geosciences >> Geochemistry

To investigate the environmental quality of the urban surface soil in Yinchuan City, the capital of Ningxia Hui Autonomous Region (Ningxia), China, we sampled surface soil and measured the concentrations of 8 toxic metals (Pb, Cr, Cu, Zn, Co, Bi, Ni and V) using X-ray fluorescence spectrometry. The enrichment characteristics and sources of these toxic metals in the soil were analyzed by the enrichment factor (EF) and multivariate statistical analysis. The results showed that the mean concentrations of these toxic metals in the soil samples were 25.0, 109.1, 16.8, 26.0, 37.2, 2.7, 25.3 and 59.9 mg/kg for Pb, Cr, Cu, Zn, Co, Bi, Ni and V, respectively, which were 1.2, 1.8, 0.8, 0.4, 3.2, 8.7, 0.7 and 0.8 times of the corresponding background values of Ningxia soil, respectively. The variations of Pb, Zn, Co, Bi and Ni concentrations in the surface soil of Yinchuan were larger than those of the other metals. Our results also showed that the toxic metals investigated in the soil had different enrichment levels. Both Co and Bi were significantly enriched, whereas Cr was only moderately enriched in the soil. There was a deficiency or minimal enrichment of the other toxic metals in the soil. Source analysis results based on the concentration, enrichment characteristics and multivariate statistical analysis indicated that Cr, V and Ni originated from a combination of fossil fuel combustion, traffic pollution and natural occurrence. Pb, Cu and Zn were predominantly derived from natural and traffic sources, while Co and Bi primarily originated from construction sources.

submitted time 2018-07-05 From cooperative journals:《Journal of Arid Land》 Hits6863Downloads1095 Comment 0

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