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Background: The fertile islands formed by shrubs are major drivers of the structure and function of desert ecosystems, affecting seedling establishment, plant–plant interactions, the diversity and productivity of plant communities, and microbial activity/diversity. Although an increasing number of studies have shown the critical importance of soil microbes in fertile island formation, how soil microbial community structure and function are affected by the different fertile island effect intensities is still unknown. As an endangered and dominant shrub species in the West Ordos Desert, Tetraena mongolica was selected for further exploration of its fertile island effect on the soil microbial community in the present study to test the following two hypotheses: (1) T. mongolica shrubs with different canopy sizes exert fertile island effects of different strengths; (2) the soil microbial community structure and function beneath the T. mongolica canopy are affected by the fertile island, and the strength of these effects varies depending on the shrub canopy size. Results: The contents of soil total nitrogen (TN) and available phosphorus (AVP) were significantly greater beneath T. mongolica shrub canopy than outside the shrub canopy. With increasing shrub canopy size, the enrichment of soil TN and AVP increased, indicating a stronger fertile island effect. The structure and function of soil microbial communities, including fungal, archaeal and bacterial communities, are affected by the fertile island effect. An increase in canopy size increased the relative abundance of Ascomycota (Fungi) and Thaumarchaeota (Archaea). For the soil microbial functional groups, the relative abundance of endophytes in the fungal functional groups; steroid hormone biosynthesis, sphingolipid metabolism, and steroid biosynthesis genes in the bacterial functional groups; and nonhomologous end-joining and bisphenol degradation functional genes in the archaeal functional groups increased significantly with increasing T. mongolica canopy size. Conclusions: These results revealed that T. mongolica had a fertile island effect, which affected the soil microbial community structure and functions, and that the fertile island effect might increase with increasing shrub canopy size. The fertile island effect may strengthen the interaction between T. mongolica shrubs and microbes, which may be beneficial to the growth and maintenance of T. mongolica. [ABSTRACT FROM AUTHOR]

Background: Wind strongly impacts plant growth, leaf traits, biomass allocation, and stem mechanical properties. However, whether there are common whole-plant wind responses among different plant species is still unclear. We tested this null hypothesis by exposing four eudicot steppe species to three different wind treatments in a field experiment: reduced wind velocity using windbreaks, ambient wind velocity, and enhanced wind velocity through a novel methodology using wind-funneling baffles. Results: Across the four species, wind generally decreased plant height, projected crown area, and stepwise bifurcation ratio, and increased root length and stem base diameter. In contrast, the response patterns of shoot traits, especially mechanical properties, to wind velocity were idiosyncratic among species. There was no significant difference in total biomass among different treatments; this might be because the negative effects on heat dissipation and photosynthesis of low wind speed during hot periods, could counteract positive effects during favorable cooler periods. Conclusions: There are common wind response patterns in plant-size-related traits across different steppe species, while the response patterns in shoot traits vary among species. This indicates the species-specific ways by which plants balance growth and mechanical support facing wind stress. Our new field wind manipulation methodology was effective in altering wind speed with the intended magnitude. Especially, our field wind-funneling baffle system showed a great potential for use in future field wind velocity enhancement. Further experiments are needed to reveal how negative and positive effects play out on whole-plant performance in response to different wind regimes, which is important as ongoing global climatic changes involve big changes in wind regimes. [ABSTRACT FROM AUTHOR]

Plant interactions greatly affect plant community structure. Dryland ecosystems are characterized by low amounts of unpredictable precipitation as well as by often having biological soil crusts (BSCs) on the soil surface. In dryland plant communities, plants interact mostly as they compete for water resources, and the direction and intensity of plant interaction varies as a function of the temporal fluctuation in water availability. Since BSCs influence water redistribution to some extent, a greenhouse experiment was conducted to test the hypothesis that the intensity and direction of plant interactions in a dryland plant community can be modified by BSCs. In the experiment, 14 combinations of four plant species (Artemisia ordosica, Artemisia sphaerocephala, Chloris virgata and Setaria viridis) were subjected to three levels of coverage of BSCs and three levels of water supply. The results show that: 1) BSCs affected plant interaction intensity for the four plant species: a 100% coverage of BSCs significantly reduced the intensity of competition between neighboring plants, while it was highest with a 50% coverage of BSCs in combination with the target species of A. sphaerocephala and C. virgata; 2) effects of the coverage of BSCs on plant interactions were modified by water regime when the target species were C. virgata and S. viridis; 3) plant interactions were species-specific. In conclusion, the percent coverage of BSCs affected plant interactions, and the effects were species-specific and could be modified by water regimes. Further studies should focus on effects of the coverage of BSCs on plant-soil hydrological processes. [ABSTRACT FROM AUTHOR]

Litter decomposition in sunny, semi‐arid and arid ecosystems is controlled by both biotic factors including litter traits and abiotic factors including UV light, but for wood decomposition it still remains uncertain which of these environmental factors are the predominant controls among different woody species. In these dry ecosystems, it is likely that the stem diameter and spatial position of the dead wood are of particular importance especially where wood can be buried versus exposed due to substrate displacement by wind. Here we focus on the fact that stem diameter can affect decomposition rates both via the relative surface exposure to sunlight or soil and via higher resource quality of narrower stems to decomposers.In a field manipulation experiment, we investigated the relative importance of litter position (sand burial vs. surface vs. suspended above the surface), UV radiation (block versus pass) and stem diameter class (<2, 2–4, 4–8, 8–13 and 13–20 mm) on the mass loss of woody litters of four shrub species in an inland dune ecosystem in northern China.We found that after 34 months of in situ incubation, the mass loss of buried woody litters was three times faster than those of suspended and surface woody litters (53.5 ± 2.7%, 17.0 ± 1.0% and 14.4 ± 1.2%, respectively). In surface and suspended positions, litter decomposition rates were almost equally low and most mass loss was during the first 2 years, when bark was still attached and UV radiation had no significant effect on woody litter mass loss. These findings suggest that sand burial is the main environmental driver of wood decomposition via its control on microbial activity. Moreover, wood N and diameter class were the predominant factors driving woody litter decomposition. A key finding was that wider stems had slower litter decomposition rates not only directly (presumably via greater relative surface exposure) but also indirectly via their higher wood dry matter content or lower wood N; these effects were modulated by litter position.Our findings highlight a dual role of stem diameter on wood decomposition, that is, via relative surface exposure and via wood traits. The accuracy and confidence of global carbon cycling models would be improved by incorporating the different effects of stem diameter on woody litter decomposition and below‐ground wood decomposition processes in drylands. A free Plain Language Summary can be found within the Supporting Information of this article. [ABSTRACT FROM AUTHOR]

Rhein (RH) has many bioactivities, but the application was limited of its poor solubility. The present study aimed to establish an efficient method for the synthesis of rhein amide derivatives (RAD) to increase the solubility and anti-tumour activity. RAD exhibited stronger anti-tumour activity than RH in MTT assay. The solubility and oil/water partition coefficient results indicated that rhein-phenylalanine and rhein-isoleucine have better absorption effect, which was consolidated in pharmacokinetic study. Then, rhein-phenylalanine and rhein-isoleucine were prepared into nanocrystals via the precipitation high-pressure homogenisation method. Additionally, the nanocrystals both displayed much higher dissolution profiles than the bulk drugs. Pharmacokinetics study indicated that the AUC0-∞ and Cmax of nanocrystals increased markedly (p < 0.01). However, the concentration of RH-Phe-NC was far less than RH-Ile-NC in plasma. Consequently, RH-Ile-NC was validated to be an applicable way to improve the bioavailability of RH, which owns a promising future in clinical application. [ABSTRACT FROM AUTHOR]

Aims Sand burial and precipitation play important roles in vegetation of inland deserts and desertified areas, and both are under strong influence of climate and land-use change. Sand deposition and precipitation both vary greatly in space and time, and different plant species, with diverse adaptations, occupy different niches along spatial gradients in the combination of sand and water availability dynamics. We hypothesized that species specificity in spatial and temporal niche occupation along such gradients is a mechanism for their co-existence and, thereby, a driver and stabilizer of biodiversity in dry, sandy areas. Location Ordos Plateau, China. Methods We conducted a 2-yr field experiment with factorial treatments of precipitation (control, slight enhancement, strong enhancement) and sand addition (control, medium addition, large addition). Plant cover of the six dominant species was followed over different seasons, as we expected different species to benefit from different treatments in different seasons and years with different weather regimes. Results Sand burial alone significantly affected plant cover of all six dominant species, while precipitation enhancement had no significant effect. Effects of sand burial on plant cover changed overall during the two hydrologically contrasting years. Our key finding was that there were multiple significant two- and three-way interactions between species, sand burial and precipitation enhancement on plant cover, while there were also multiple two- and three-way interactions involving species, sand burial or precipitation treatment with year and/or season. Conclusion Our results supported our hypothesis, i.e. the co-existence of species in a semi-arid sand dune can be explained from the different niches they occupy in terms of seasonal and year-to-year variation in precipitation in combination with sand deposition regime. The interactions of these drivers on plant cover with experimental enhancement of precipitation, mimicking a realistic scenario for this region, suggest that shifts in species composition are to be expected this century. More generally, our findings advance our understanding of what drives species co-existence and thereby biodiversity, now and in the future. [ABSTRACT FROM AUTHOR]

Yunnan Province with numerous international rivers has huge impacts on downstream countries such as Burma, Laos and Vietnam. Agricultural expansion in Yunnan has conferred and continues to confer detrimental impacts on environments. In the past 43 years (1960-2003), the increase in crop yield was associated with a 99.1-fold increase in fertilizers, 2.0-fold in pesticides, and 0.4-fold in cultivated lands, respectively. Based on linear regression of the past trend, the next doubling of crop yield in the future would be accompanied by the increase in fertilizer application (from about 1.3×109 kg to 3.6×109 kg), and the increase in application of pesticides (from about 2.7×107kg to 9.6×107 kg). Similarly, the total amount of cultivated lands would increase from about 5.9×106 hato 9.3×106 ha. In the past decades, these changes have caused a series of environmental problems such as agricultural non-point source pollution (ANSP), deforestation, land degradation, and biodiversity loss. If the escalating status continues as our prediction, those problems would get worse and be tough to be dealt with. As for the situation in this region, some practices to minimize the impacts should be implemented in controlling population growth, protecting wetlands, developing tourism, and utilizing fertilizers and pesticides more rationally. [ABSTRACT FROM AUTHOR]