Map indicating the distribution of <i>Fritillaria</i> in China.

<p>The distribution area of each species is drawn according to the records in the FOC and Flora Xinjiangensis. Photographs of the species are also provided.</p

Comparison of 13 <i>Fritillaria</i> cp genomes with <i>F</i>. <i>cirrhosa</i> as the reference.

<p>LSC: long single copy region; SSC: short single copy region; IRa and IRb: inverted regions. Gray arrow: gene and translation direction; blue block: exon of the gene; red block: conserved non-coding sequences (CNS). Sequence identities are labeled at the right side and range between 50%-100%.</p

Gene map of the <i>Fritillaria</i> cp genome.

<p>Genes belonging to different functional groups are color-coded. The dashed area in the inner circle indicates the GC content. Cp genome size ranges are provided for the seven Xinjiang <i>Fritillaria</i> species.</p

Complete chloroplast genome of seven <i>Fritillaria</i> species, variable DNA markers identification and phylogenetic relationships within the genus

<div><p><i>Fritillaria</i> spp. constitute important traditional Chinese medicinal plants. Xinjiang is one of two diversity hotspots in China in which eight <i>Fritillaria</i> species occur, two of which are endemic to the region. Furthermore, the phylogenetic relationships of Xinjiang <i>Fritillaria</i> species (including <i>F</i>. <i>yuminensis</i>) within the genus are unclear. In the present study, we sequenced the chloroplast (cp) genomes of seven <i>Fritillaria</i> species in Xinjiang using the Illumina HiSeq platform, with the aim of assessing the global structural patterns of the seven cp genomes and identifying highly variable cp DNA sequences. These were compared to previously sequenced <i>Fritillaria</i> cp genomes. Phylogenetic analysis was then used to evaluate the relationships of the Xinjiang species and assess the evolution of an undivided stigma. The seven cp genomes ranged from 151,764 to 152,112 bp, presenting a traditional quadripartite structure. The gene order and gene content of the seven cp genomes were identical. A comparison of the 13 cp genomes indicated that the structure is highly conserved. Ten highly divergent regions were identified that could be valuable in phylogenetic and population genetic studies. The phylogenetic relationships of the 13 <i>Fritillaria</i> species inferred from the protein-coding genes, large single-copy, small single-copy, and inverted repeat regions were identical and highly resolved. The phylogenetic relationships of the species corresponded with their geographic distribution patterns, in that the north group (consisting of eight species from Xinjiang and Heilongjiang in North China) and the south group (including six species from South China) were basically divided at 40°N. Species with an undivided stigma were not monophyletic, suggesting that this trait might have evolved several times in the genus.</p></div

The evolutionary progression of stigmatic traits within the genus.

<p>The evolutionary progression of stigmatic traits within the genus.</p

Comparison of LSC, SSC, and IR border regions among the 13 <i>Fritillaria</i> cp genomes.

<p>Colored boxes for genes represent the gene position. ψ: pseudogenes. *: these six species were redrawn according to Park et al. [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0194613#pone.0194613.ref021" target="_blank">21</a>].</p

Variable site analyses in <i>Fritillaria</i> chloroplast genomes.

<p>Variable site analyses in <i>Fritillaria</i> chloroplast genomes.</p

Table1_Fertile Island Effect by Three Typical Woody Plants on Wetlands of Ebinur Lake, northwestern China.DOCX

Desertification poses a permanent threat to the security of arid ecosystems. Perennial arid vegetation plays a crucial role in maintaining the structure and function of arid ecosystems and slowing the process of desertification by forming “fertile islands” under the tree canopy. However, the process of formation and development of these fertile islands remains uncertain. Here, we explored how three typical woody plants (i.e., Populus euphratica, Haloxylon ammodendron, and Nitraria tangutorum) in the Ebinur Lake Basin of northwestern China differed in their soil nitrogen and phosphorus. 1) Significant differences of organic carbon and total and available nitrogen/phosphorus were observed in the soil among the three typical woody plant-dominated ecosystems. Populus euphratica had significant differences of N and P contents between the canopy and bare soils, except for ammonium nitrogen. 2) Our RDA analysis revealed that the major factors that influenced the soil nutrient differences among the three vegetations were plant crown width, soil water content, salinity, and pH. 3) The organic carbon content of bare soil was significantly correlated with N and P in all the three vegetations. This study contributes to our understanding of the factors that influence the fertile island effect in arid ecosystems, which may contribute to soil conservation in arid areas.</p

Table_1_Impact of meteorological variability on diurnal and seasonal net ecosystem productivity in a desert riparian forest ecosystem.xlsx

The desert riparian forests are susceptible to meteorological changes and contribute significantly to the net ecosystem productivity (NEP) variations of arid ecosystems. However, the responsive patterns of their NEP variations to the meteorological variabilities remain inadequately comprehended. To address this gap, we utilized seven years of eddy covariance flux measurements in a representative desert riparian forest to investigate the NEP variations and its response to changing meteorological factors across diverse temporal scales. The results revealed significant periodic variations in half-hourly NEP, with dominant cycles spanning from five hours to one year, with a principal oscillation period of one day. Key meteorological factors including global solar radiation (Rg), relative humidity (RH), air temperature (Ta), soil temperature (Ts), and vapor pressure deficit (VPD) exhibited synchronization with NEP on daily scales. This synchronization, coupled with the observed one-day periodic NEP variations, provides robust evidence supporting the existence of a circadian rhythm in the ecosystem carbon exchange of desert riparian forest regulated by meteorological conditions. Seasonal patterns were significant in the impact of Rg phase, Ta diurnal amplitude, and VPD diurnal amplitude on NEP diurnal amplitude and phase. The NEP diurnal amplitude significantly, directly, and positively affected daily NEP in both the dormant and growing seasons, whereas its phase yielded significant negative effects (P< 0.05). The averages, amplitudes, and phases of diurnal meteorological conditions controlled the daily NEP by regulating NEP diurnal amplitude and phase. These findings provide evidence that the variability in circadian rhythms, caused by the increase in diurnal Ta and VPD, significantly impact the daily NEP at an ecosystem scale. This study enriches our comprehension of the meteorological mechanisms governing diurnal and seasonal carbon uptake dynamics within desert riparian forests, providing fresh insights into the direct and indirect roles of climate change in shaping patterns of ecosystem carbon exchange.</p

Effects of Simulated Nitrogen Deposition on Soil Respiration in a <i>Populus euphratica</i> Community in the Ebinur Lake Area, a Desert Ecosystem of Northwestern China

<div><p>One of the primary limiting factors for biological activities in desert ecosystems is nitrogen (N). This study therefore examined the effects of N and investigated the responses of an arid ecosystem to global change. We selected the typical desert plant <i>Populus euphratica</i> in a desert ecosystem in the Ebinur Lake area to evaluate the effects of N deposition on desert soil respiration. Three levels of N deposition (0, 37.5 and 112.5 kg·N·ha^-1·yr^-1) were randomly artificially provided to simulate natural N deposition. Changes in the soil respiration rates were measured from July to September in both 2010 and 2013, after N deposition in April 2010. The different levels of N deposition affected the total soil N, soil organic matter, soil C/N ratio, microorganism number, and microbial community structure and function. However, variable effects were observed over time in relation to changes in the magnitude of N deposition. Simulated high N deposition significantly reduced the soil respiration rate by approximately 23.6±2.5% (P<0.05), whereas low N deposition significantly increased the soil respiration rate by approximately 66.7±2.7% (P<0.05). These differences were clearer in the final growth stage (September). The different levels of N deposition had little effect on soil moisture, whereas N deposition significantly increased the soil temperature in the 0–5 cm layer (P<0.05). These results suggest that in the desert ecosystem of the Ebinur Lake area, N deposition indirectly changes the soil respiration rate by altering soil properties.</p></div