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Glycophyte biomass − derived biochars have proven to be effective in the amelioration of acidic soil. However, there is scarce information on the characteristics and soil amelioration effects of halophyte-derived biochars. In this study, a typical halophyte Salicornia europaea, which is mainly distributed in the saline soils and salt-lake shores of China, and a glycophyte Zea mays, which is widely planted in the north of China, were selected to produce biochars with a pyrolysis process at 500 °C for 2 h. S. europaea-derived and Z. mays-derived biochars were characterized in elemental content, pores, surface area, and surface functional groups, and then by using a pot experiment their potential utilizable value as acidic soil conditioner was evaluated. The results showed that compared with Z. mays-derived biochar, S. europaea-derived biochar displayed higher pH, ash contents, base cations (K+, Ca2+, Na+, and Mg2+) contents and exhibited more larger surface area and pore volume than Z. mays-derived biochar. Both biochars had abundant oxygen-containing functional groups. Upon treating the acidic soil, the pH of acidic soil was increased by 0.98, 2.76, and 3.36 units after the addition of 1%, 2%, and 4% S. europaea-derived biochar, while it was increased only by 0.10, 0.22, and 0.56 units at 1%, 2%, and 4% Z. mays-derived biochar. High alkalinity in S. europaea-derived biochar was the main reason for the increase of pH value and base cations in acidic soil. Thus, application of halophyte biochar such as S. europaea-derived biochar is an alternative method for the amelioration of acidic soils. [ABSTRACT FROM AUTHOR]

In China, Wedelia trilobata (WT) is among the top most invasive plant species. The prediction of its growth, using different efficient methods under different environmental conditions, is the optimal objective of ecological research. For this purpose, Wedelia trilobata and its native plant species Wedelia chinensis (WC) were grown in mixed cultures under different levels of submergence and eutrophication. The multiple linear regression (MLR) and artificial neural network (ANN) models were constructed, with different morphological traits as the input in order to predict dry weight as the output for both plant species. Correlation and stepwise regression analysis (SWR) were used to find the best input variables for the ANN and MLR models. Plant height, number of nodes, chlorophyll content, leaf nitrogen, number of leaves, photosynthesis, and stomatal conductance were the input variables for WC. The same variables were used for WT, with the addition of root length. A network with the Levenberg–Marquart learning algorithm, back propagation training algorithm, Sigmoid Axon transfer function, and one hidden layer, with four and six neurons for WC and WT, respectively, was created. The best ANN model for WC (7-4-1) has a coefficient of determination (R2) of 0.98, root mean square error (RMSE) of 0.003, and mean absolute error (MAE) of 0.001. On the other hand, the ANN model for WT (8-6-1) has R2 0.98, RMSE 0.018, and MAE 0.004. According to errors and coefficient of determination values, the ANN model was more accurate than the MLR one. According to the sensitivity analysis, plant height and number of nodes are the most important variables that support WT and WC growth under submergence and eutrophication conditions. This study provides us with a new method to control invasive plant species' spread in different habitats. [ABSTRACT FROM AUTHOR]

Background and aims: The encroachment of halophytic shrubs including tamarisk into saline meadows is accelerating with global warming in the northern Tarim Basin, Xinjiang, China. However, the role of tamarisk in the spatial heterogeneity of soil resources in different desertification stages remains unclear. Methods: The influences of tamarisk on soil resources were assessed via soil salinity and soil organic matter (SOM) measurements under tamarisk canopies and in interspaces. Geostatistical methods were applied to compare the spatial heterogeneity of these soil properties in three regions representing different desertification stages: 1) a meadow with shrubs, 2) a shrubland and 3) shrub duneland. Results: The highest coefficient of variation (CVs) of the soil analytes and most developed 'resource islands' were observed in the shrubland. The overall variation of most of the soil variables was lower in the shrub duneland than in the shrubland and similar to that in the meadow with shrubs. The distribution of SOM and most soil salinity ions were moderately spatially dependent in the meadow with shrubs but highly spatially dependent in the shrubland and shrub duneland. The autocorrelation distances of the most of soil salinity ions were approximately 6- to 15- fold and 2- to 4-fold highest than the tamarisk shrub size in the meadow with shrubs and shrubland, respectively. In contrast, the distribution range of total soil salinity (TSS) and soil K, Na and Cl in the shrub duneland were 1/5 ~ 2/3 of the tamarisk size. Conclusions: 1) Compared with the effect of tamarisk on soil resource heterogeneity in the meadow with shrubs, that in the shrubland was enhanced due to the larger shrub size and more open and scattered canopy in the latter.2) Although the largest shrub size were observed in the shrub duneland, the role of tamarisk in redistributing soil resources was overriden by those of physical processes due to the loose canopy. 3) The spatial heterogeneity of soil resources is determined by not only tamarisk but also environmental factors, such as the connectivity of bare areas and topography. [ABSTRACT FROM AUTHOR]

Species composition and productivity are influenced by water and N availability in semi-arid grasslands. To assess the effects of increased N deposition and water supply on plant species composition and productivity, two field experiments with four N addition treatments, and three N and water combination treatments were conducted in alpine grassland in the mid Tianshan mountains, northwest China. When considering N addition alone, aboveground biomass (AGB) of forbs (F) responded less to N addition than AGB of grasses (G). G increased as an effect of N combined with water addition but F did not show such an effect, reflecting a stronger response of grasses to the interaction of water availability and N than forbs. Under all treatments, N allocation to the aboveground tissue did not change for either forbs or grasses. N deposition and water addition did not alter species richness in the present study. These results suggest that N addition generally promoted AGB but had little effect on species richness in wet years. Snowfall in winter combined with rainfall in the early growing season likely plays a critical role in regulating plant growth of the subsequent year in the alpine grassland. [ABSTRACT FROM AUTHOR]

This paper introduces the concept, status and problems of China's environmental management system at the rural-urban interface. The problems of environmental management are closely related to rapid urbanisation and the traditional rural-urban dual management system. Integrating rural and urban environmental concerns into environmental policy and management remains a challenge at the rural-urban interface because of the institutional mismatch between urban environmental policies and rural environmental issues. From the current management status, management goals, related laws and major measures the problems in terms of management process are (1) lack of clear identification of environmental issues; (2) lack of clearly defined responsibilities; (3) inappropriate policies and regulation systems; (4) ineffective implementation of environmental policies and regulations; and (5) lack of supervision in environmental management. The existing environmental management pattern leads to a lack of environmental awareness in residents and environmental quality deterioration in the rural-urban interface. This paper suggests a new environmental management pattern constituting government-led environmental management committees and environmental organisations of public participation for the rural-urban interface in China. This pattern is aimed at facilitating reform of the current rural-urban interface environmental management and promoting integrated development in China's urban and rural areas. [ABSTRACT FROM AUTHOR]

Phreatic evaporation is a great lose for shallow groundwater in the Taklimakan Desert. Given soil type and groundwater table, the limiting rate of phreatic evaporation is defined as the maximum of water transferred from groundwater to soil surface per unit time, which is a key parameter and control condition for phreatic evaporation model developing. The soil water characteristic curve for the aeolian sandy soil in the Taklimakan Desert was fitted with the least square method based on the formula of soil moisture characteristics curve proposed by Van Genuchten, using observed soil moisture and soil water suction data. The unsaturated hydraulic conductivity was determined by the instantaneous profile method in situ and the calculation formula for unsaturated hydraulic conductivity was established. According to the steady flow theory, the quasi-analytical solution of limiting rate of phreatic evaporation was derived on the basis of generalization of the formula of unsaturated hydraulic conductivity. The results show that the soil moisture characteristics in the Taklimakan Desert can be well described by Van Genuchten's formula, and the limiting rate of phreatic evaporation declines by power function with the descending of groundwater table. [ABSTRACT FROM AUTHOR]

Excessive application of nitrogen fertilizers and improper methods of irrigation under conventional management are common problems in the cotton fields of northwestern China. Efficiency-enhanced management, based on the water and nitrogen dynamics and crop requirements, has been used as a valuable strategy in different crops. The present study aimed to compare efficiency-enhanced management and conventional management of irrigation and nitrogen fertilization in the cotton fields at the Junggar Basin (Shihezi) and Tarim Basin (Cele) of northwestern China. Compared with conventional management, efficiency-enhanced management reduced the amount of N fertilizer by 41% in Cele and 44% in Shihezi, and the irrigation quantity by 35% in Cele and 24% in Shihezi. However, the cotton yield under efficiency-enhanced management was similar to that found under conventional management at both the experimental sites. The efficiency-enhanced management increased the water-use efficiency (WUE) and reduced the residual soil mineralizable N (Nmin) and apparent N losses. This study indicated that efficiency-enhanced management can significantly enhance the utilization efficiency of irrigation water and N fertilizers for cotton production in the fields of northwestern China. [ABSTRACT FROM AUTHOR]

• Apocynum is widely distributed and geographically diverse plant species. • Apocynum exhibits several medical and economic benefits. • Salt tolerance in Apocynum is associated with better redox- and osmo-regulation. • Apocynum can be used to remediate saline area due to its better ability to remove salts from soil and sequester in leaves. • Both sexual and asexual propagation methods make Apocynum cultivation a great opportunity for the vegetation restoration on saline soils Apocynum belongs to Apocynaceae family, is known as highly stress tolerant plant genus. Apocynum venetum L. and Apocynum pictum Schrenk, locally known as luobuma in China, are used as traditional medical plants and cash crops, and used for the phytoremediation of degraded saline lands. This review was aimed to critically analyzed the biological uses, salt tolerance mechanisms, and propagation methods of both Apocynum species to highlight the significance of the cultivation of Apocynum as a great opportunity for the vegetation restoration in saline soils in the arid region. In saline area, where arable crop production is nearly impossible due to high salt toxicity in soil, cultivation of Apocynum can reduce the levels of salt in soils and can also provide livelihood in the form of high-quality fibre. Critical literature analysis showed that overall salinity tolerance in Apocynum is associated with the regulation of redox regulation and ionic homeostasis, however their molecular regulation has not been identified yet. Findings such as removal of Na+ from soils and enhanced accumulation of flavonoids and antioxidants in leaves under saline environment, are useful in understanding the complex network of salt tolerance in Apocynum. Moreover, the practical adoption and application of different sexual and asexual propagation methods also play an important role in the successful cultivation of Apocynum in saline soils. To sum up, there are broad prospects for vigorously developing Apocynum industry by utilizing saline-alkali lands and carrying out research on cultivation technology and conservation strategy of Apocynum resources in arid lands. [ABSTRACT FROM AUTHOR]

Soil salinization threatens agricultural sustainability, especially for arid and semiarid regions. Planting euhalophytes with drip irrigation is proposed to be a feasible solution for the reclamation of saline soils. Thus, by planting an annual halophyte Suaeda salsa with drip irrigation, we assessed the potential of S. salsa to accumulate high amount of salt from soil and change in soil salinity levels in a three-year field study in arid northwestern China. The aboveground parts of S. salsa contained >20% ash salt on a dry weight basis and Na+ and Cl− were the main components. For each year, salt extraction by the aboveground part of S. salsa was ranged from 3749 to 3911 kg ha−1. Soil salinity dramatically decreased year by year by the cultivation of S. salsa , especially in the topsoil layer (0–40 cm). Our study suggested that consecutive cultivation of S. salsa with drip-irrigation is an efficient method to reclaim saline soil in arid and semiarid regions. [ABSTRACT FROM AUTHOR]

• Bacterial communities were geographically distributed along the longitude gradient. • Salinity affected bacterial diversity but not bacterial abundance. • Salinity was the main environmental driver of bacterial communities. • Salinity levels altered the modularity in the bacterial co-occurrence network. Saline soils suppress plant growth and reduce yield worldwide, thereby pose a serious threat to agriculture. Although microbes drive major biogeochemical cycles and play an integral role in agricultural production, understanding of the microbial distribution patterns in saline agricultural systems remains limited. Here we investigated the co-occurrence and biogeographical patterns of bacterial communities in saline agricultural soils at a regional scale in north-west China. Our results revealed a trend towards increasing bacterial abundance at higher longitudes. By contrast, bacterial diversity exhibited different spatial patterns and declined with increasing salinity. Bacteroidetes , Gammaproteobacteria , Alphaproteobacteria and Gemmatimonadetes were the dominant groups across all soil samples (>5% of all sequences). Additionally, members belonging to Flavobacteriaceae , Cytophagaceae , Halomonadaceae , Acidobacteria and Gemmatimonadetes were identified as indicators across the salinity gradient. Salinity levels also affected the modularity of bacterial co-occurrence networks, with module composition differing between soil salinity levels. Bacteria belonging to Acidobacteria subgroup 4, Acidobacteria subgroup 6, Gemmatimonadetes and Rhodospirillales were statistically identified as the keystone taxa. Geographical distance explained 5.08% of the community variation, whereas soil parameters explained 27.26% variation, with salinity as a major driver explaining 15.18% of the variation. Therefore, bacterial communities were geographically distributed along the longitude gradient, and soil salinity was more important than geographical isolation in shaping soil bacterial communities. Taken together, our results indicate that salinity alters bacterial network modularity and drives spatial distribution in saline agricultural soils. [ABSTRACT FROM AUTHOR]