Giant reed (Arundo donax L.) has great potential for phytoremediation of N balance-disrupted soils due to its large plant biomass production and strong N use efficiency. Soil properties and the artificial modification in agricultural production cause a heterogeneous distribution of N. However, little is known about the differential responses of A. donax at varying N abundances. Herein, giant reed seedlings were grown in solutions with low, moderate and high N supply under hydroponic culture system. We found that both nonoptimal N inhibited the growth and biomass accumulation of A. donax, which was severely repressed by high N. While phytophysiological assays showed that N stress decreased photosynthetic rate and Fv/Fm by increasing reactive oxygen species (ROS) accumulation and lipid peroxidation, the activity of antioxidant enzymes and redox poise in leaves and roots was promoted to minimize excessive ROS accumulation and oxidative stress. High-throughput transcriptomic profiling revealed a total of 19,848 and 16,736 differentially expressed genes (DEGs) under low N and high N conditions, respectively. Based on the results of DEG function annotation and enrichment analyses, varying N abundances up-regulated the expression of a number of genes involved in ROS production and antioxidant defense systems and down-regulated most genes related to photosynthesis, which may contribute to plant response. The expression of 76 and 64 transcription factors (TFs) in leaves, 88 and 110 TFs in roots were up-regulated under low N and high N conditions, respectively, which may contribute to alleviating damage caused by varying N treatment. Our findings would enrich our understanding of the growth and development changes of A. donax plants under low N or high N conditions, and might also provide suitable gene resources and important implications for the genetic improvement of plant N resistance and accumulation through molecular engineering of these genes under varying N abundances in soils.

Daurian Pika ( Ochotona dauurica) are steppe-dwelling burrowing mammals with the potential to have large effects on central Asian grasslands due to their extensive range, propensity to occur at extremely high density, and roles as ecosystem engineers and important prey species. The few studies that have been done are mostly from northern China and Russia, while little research has been done in the majority of their range in Mongolia. We studied a population of Daurian Pika in the Darhad Valley of northern Mongolia, near the southern edge of the permafrost, where climate change is progressing rapidly. We evaluated pika populations at 87 random plots across a large 40 x 125 km area and assessed the impact of factors related to vegetation cover, grazing, and soils that predicted their occupancy and an index of their density (number of active burrows). We found that pikas were more likely to occur in areas with taller grass and higher forb cover, and burrow densities were higher in areas with low or moderate grazing and lower soil moisture. In summer, pikas mainly foraged on grass compared with forbs-while in fall, forbs appeared to be selected for in haypiles. Dense pika burrow systems had taller grasses and forbs in their immediate vicinity, suggesting that in some cases, pika could help promote plant growth for other grazers. Long-tailed Ground Squirrel (Urocitellus undulatus) was the second most abundant small mammal in our study sight and selected for areas with high cover of overgrazing indicator species and for short forbs, providing little evidence for competition with Daurian Pika. Our results suggest that shorter grass (similar to 1 cm) can decrease pika occupancy by 75%, while heavy grazing may decrease burrow density by 66% in dry soils. With grazing pressure in Mongolia increasing dramatically since the 1990s, future research is strongly needed to assess the impacts of grazing on this keystone species.

Restoration involves the recovery and repair of environments because environmental damage is not always irreversible, and communities are not infinitely resilient to such harm. When restoration projects are applied to nature, either directly or indirectly these may take the form of ecological, forestry or hydrological restoration, for example. In the current scenario of global climate change and increasing intensity of disturbances the importance of restoration in all types of ecosystems in order to adapt to the new conditions (so called prestoration) is evident. Whatever the objective of the restoration initiative, there is a lack of consensus as regards common indicators to evaluate the success or failure of the different initiatives implemented. In this study, we have carried out an extensive meta-analysis review of scientific papers aiming to evaluate the outcomes of restoration projects. We have done a review and selected 95 studies implemented in Europe. We explored the main pre-restoration land cover in which restoration initiatives have been implemented, the main causes of degradation, the objective of the restoration action and the indicators selected to analyze the success or failure of the action. We identified a total of 84 indicators in the analyzed papers and compared with the ones proposed for forest in the recent Nature Restoration Law. The analysis revealed five indicators commonly used for the evaluation of restoration initiatives (abundance, coverage, density, Ellenberg indicator, and richness), even where the initial objective has not yet been achieved. Our findings underscore both the benefits and challenges associated with a specific set of harmonized indicators for evaluating the success or failure of restoration initiatives.

Mining has led to dramatic ecosystem degradation, the destruction of vegetation and irreversible damage to soil structure and nutrient cycling; additionally, heavy metal (HM) contamination has affected soil nitrogen (N) cycle-associated microorganisms and disrupted soil aggregate structure. To explore the mechanism of soil N recovery in mining areas, we investigated the effects of two N fertilizers (urea (U) and ammonium chloride (AC)) and nine different fertilization patterns on the nitrification process and ammonia oxidizers in soil aggregates via incubation experiments. The results showed that different N treatments had different influences on the distribution of AOA and AOB amoA gene abundance and microbial community structure in soil aggregates. The AOB amoA gene abundance was significantly greater than the AOA amoA gene abundance in aggregates. The dominant species of AOA and AOB were Nitrososphaera and Nitrosospira , respectively, which were mainly found in microaggregates and accounted for 10.3 % to 25.0 % and 31.5 % to 60.1 %, respectively, of the microaggregates. Dissolved organic nitrogen (DON) can be used as an important variable to explain variations in AOA communities, and microbial nitrogen (MBN) content, tartaric acid content, cellulase activity and AOB amoA gene abundance can be used as important variables to explain variations in AOB communities. N fertilizer addition resulted in potential ammonia oxidation (PAO) values ranging from 0.079 to 0.236, 0.100 to 0.5953 and 0.146 to 0.905 mu g.NO2--N d(-1) g(-1) in mega-, macro- and microaggregates, respectively, which suggested that PAO values increased with decreasing aggregate size. In addition, the total nitrification potential (TNP) in macroaggregates was greater than that in mega- and microaggregates, which was the main reason for the increase in the NO3 content in macroaggregates. AOB amoA gene abundance was significantly positively correlated with TNP, and AOB amoA gene abundance was more significantly positively correlated with PAO values than was AOA gene abundance, which suggests that AOB dominated ammonia oxidation and nitrification processes in aggregates. Our research contributes to an understanding of the mechanisms underlying the effects of different types of N fertilizers on nitrification processes and ammonia oxidizers in soil aggregates and provides insights into N management in contaminated soils in mining areas.

1. Factors shaping arthropod and plant community structure at fine spatial scales are poorly understood. This includes microclimate, which likely plays a large role in shaping local community patterns, especially in heterogeneous landscapes characterised by high microclimatic variability in space and in time.2. We explored differences in local microclimatic conditions and regional species pools in two subarctic regions: Kilpisj & auml;rvi in north-west Finland and Varanger in north-east Norway. We then investigated the relationship between fine-scale climatic variation and local community characteristics (species richness and abundance) among plants and arthropods, differentiating the latter into two groups: flying and ground-dwelling arthropods collected by Malaise and pitfall traps, respectively. Arthropod taxa were identified through DNA metabarcoding. Finally, we examined if plant richness can be used to predict patterns in arthropod communities.3. Variation in soil temperature, moisture and snow depth proved similar between regions, despite differences in absolute elevation. For each group of organisms, we found that about half of the species were shared between Kilpisj & auml;rvi and Varanger, with a quarter unique to each region.4. Plants and arthropods responded largely to the same drivers. The richness and abun-dance of both groups decreased as elevation increased and were positively correlated with higher soil moisture and temperature values. Plant species richness was a poor predictor of local arthropod richness, in particular for ground-dwelling arthropods.5. Our results reveal how microclimatic variation within each region carves pro-nounced, yet consistent patterns in local community richness and abundance out of a joint species pool.

Changes in soil CO2 and N2O emissions due to climate change and nitrogen input will result in increased levels of atmospheric CO2 and N2O, thereby feeding back into Earth's climate. Understanding the responses of soil carbon and nitrogen emissions mediated by microbe from permafrost peatland to temperature rising is important for modeling the regional carbon and nitrogen balance. This study conducted a laboratory incubation experiment at 15 and 20 degrees C to observe the impact of increasing temperature on soil CO2 and N2O emissions and soil microbial abundances in permafrost peatland. An NH4NO3 solution was added to soil at a concentration of 50 mg N kg(-1) to investigate the effect of nitrogen addition. The results indicated that elevated temperature, available nitrogen, and their combined effects significantly increased CO2 and N2O emissions in permafrost peatland. However, the temperature sensitivities of soil CO2 and N2O emissions were not affected by nitrogen addition. Warming significantly increased the abundances of methanogens, methanotrophs, and nirK-type denitrifiers, and the contents of soil dissolved organic carbon (DOC) and ammonia nitrogen, whereas nirS-type denitrifiers, beta-1,4-glucosidase (beta G), cellobiohydrolase (CBH), and acid phosphatase (AP) activities significantly decreased. Nitrogen addition significantly increased soil nirS-type denitrifiers abundances, beta-1,4-N- acetylglucosaminidase (NAG) activities, and ammonia nitrogen and nitrate nitrogen contents, but significantly reduced bacterial, methanogen abundances, CBH, and AP activities. A rising temperature and nitrogen addition had synergistic effects on soil fungal and methanotroph abundances, NAG activities, and DOC and DON contents. Soil CO2 emissions showed a significantly positive correlation with soil fungal abundances, NAG activities, and ammonia nitrogen and nitrate nitrogen contents. Soil N2O emissions showed positive correlations with soil fungal, methanotroph, and nirK-type denitrifiers abundances, and DOC, ammonia nitrogen, and nitrate contents. These results demonstrate the importance of soil microbes, labile carbon, and nitrogen for regulating soil carbon and nitrogen emissions. The results of this study can assist simulating the effects of global climate change on carbon and nitrogen cycling in permafrost peatlands.

The Moon can have elevated chlorine (Cl) isotope ratios, much higher than any other Solar System objects. Deciphering the Cl isotope compositions of volcanic lunar samples is critical for unraveling the volcanic processes and volatile inventory of the Moon's interior. However, the processes and mechanisms of Cl isotope fractionation are not yet fully understood through previous studies on lunar samples. The China's Chang'e-5 (CE5) basalt samples were collected far from the Apollo and Luna landing sites, and dated at about 2.0 billion years ago (Ga), approximately 1 Ga younger than previously reported lunar basalts. The CE5 samples, therefore, provide an opportunity to investigate Cl isotope characteristics and fractionation mechanisms during a younger lunar volcanism. In this study, we performed systematic petrography, mineral chemistry, volatile abundances and distribution, and Cl isotopic studies on the CE5 apatite via a combination of scanning electron microscopy, electron probe microanalyser, and nanoscale secondary ion mass spectrometry. The CE5 apatite grains from basalt clasts and fragments have subhedral to euhedral shapes with grains sizes mostly less than 10 mu m, mainly coexisting with the mesostasis, fayalite olivine, and the margins of pyroxene. These apatites are F-dominated (0.91-3.93 wt%) with a Cl abundance range of 820 to 11989 mu g.g(-1) and a water abundance range of 134 to 6564 mu g.g-1, similar to those in the mare samples previously reported. Chlorine displays notable zoning distributions in some CE5 apatite grains with higher abundance at the rims gradually decrease towards the cores. Chlorine isotopic compositions of CE5 apatite vary from 4.5 to 18.9%o, positively correlated with the Cl abundances. These lines of evidence suggest that magmatic degassing of Cl-bearing species during the crystallisation of apatite at or near the lunar surface could have resulted in a large Cl isotope fractionation. Our new findings highlight a significant role of magmatic fractionation of Cl isotopes during crystallisation of mare lavas and provide clues for determining the primordial Cl isotopic signature of the Moon.(c) 2022 Elsevier B.V. All rights reserved.

Substantial amounts of topsoil organic matter (OM) in Arctic Cryosols have been translocated by the process of cryoturbation into deeper soil horizons (cryoOM), reducing its decomposition. Recent Arctic warming deepens the Cryosols' active layer, making more topsoil and cryoOM carbon accessible for microbial transformation. To quantify bacteria, archaea and selected microbial groups (methanogens - mcrA gene and diazotrophs - nifH gene) and to investigate bacterial and archaeal diversity, we collected 83 soil samples from four different soil horizons of three distinct tundra types located in Qikiqtaruk (Hershel Island, Western Canada). In general, the abundance of bacteria and diazotrophs decreased from topsoil to permafrost, but not for cryoOM. No such difference was observed for archaea and methanogens. CryoOM was enriched with oligotrophic (slow-growing microorganism) taxa capable of recalcitrant OM degradation. We found distinct microbial patterns in each tundra type: topsoil from wet-polygonal tundra had the lowest abundance of bacteria and diazotrophs, but the highest abundance of methanogens. Wet-polygonal tundra, therefore, represented a hotspot for methanogenesis. Oligotrophic and copiotrophic (fast-growing microorganism) genera of methanogens and diazotrophs were distinctly distributed in topsoil and cryoOM, resulting in different rates of nitrogen flux into these horizons affecting OM vulnerability and potential CO2 and CH4 release.

Background: Permafrost degradation may develop thermokarst landforms, which substantially change physicochemical characteristics in the soil as well as the soil carbon stock. However, little is known about changes of bacterial community among the microfeatures within thermokarst area. Results: We investigated bacterial communities using the Illumina sequencing method and examined their relationships with soil parameters in a thermokarst feature on the northern Qinghai-Tibetan Plateau. We categorized the ground surface into three different micro-relief patches based on the type and extent of permafrost collapse (control, collapsing and subsided areas). Permafrost collapse significantly decreased the soil carbon density and moisture content in the upper 10 cm samples in the collapsing areas. The highest loading factors for the first principal component (PC) extracted from the soil parameters were soil carbon and nitrogen contents, while soil moisture content and C:N ratios were the highest loading factors for the second PC. The relative abundance of Acidobacteria decreased with depth. Bacterial diversity in subsided areas was higher than that in control areas. Conclusions: Bacterial community structure was significantly affected by pH and depth. The relative abundance of Gemmatimonadetes and Firmicutes were significantly correlated with the first and second PCs extracted from multiple soil parameters, suggesting these phyla could be used as indicators for the soil parameters in the thermokarst terrain.

Moderately volatile elements (MVE) are key tracers of volatile depletion in planetary bodies. Zinc is an especially useful MVE because of its generally elevated abundances in planetary basalts, relative to other MVE, and limited evidence for mass-dependent isotopic fractionation under high-temperature igneous processes. Compared with terrestrial basalts, which have delta Zn-66 values (per mille deviation of the Zn-66/Zn-64 ratio from the JMC-Lyon standard) similar to some chondrite meteorites (similar to+0.3 parts per thousand), lunar mare basalts yield a mean delta Zn-66 value of +1.4 +/- 0.5 parts per thousand (2 st. dev.). Furthermore, mare basalts have average Zn concentrations similar to 50 times lower than in typical terrestrial basaltic rocks. Late-stage lunar magmatic products, including ferroan anorthosite, Mg- and Alkali-suite rocks have even higher delta Zn-66 values (+3 to +6 parts per thousand). Differences in Zn abundance and isotopic compositions between lunar and terrestrial rocks have previously been interpreted to reflect evaporative loss of Zn, either during the Earth-Moon forming Giant Impact, or in a lunar magma ocean (LMO) phase. To explore the mechanisms and processes under which volatile element loss may have occurred during a LMO phase, we developed models of Zn isotopic fractionation that are generally applicable to planetary magma oceans. Our objective was to identify conditions that would yield a delta Zn-66 signature of similar to+1.4%0 within the lunar mantle. For the sake of simplicity, we neglect possible Zn isotopic fractionation during the Giant Impact, and assumed a starting composition equal to the composition of the present-day terrestrial mantle, assuming both the Earth and Moon had zinc 'consanguinity' following their formation. We developed two models: the first simulates evaporative fractionation of Zn only prior to LMO mixing and crystallization; the second simulates continued evaporative fractionation of Zn that persists until similar to 75% LMO crystallization. The first model yields a relatively homogenous bulk solid LMO delta Zn-66 value, while the second results in a stratification of delta Zn-66 values within the LMO sequence. Loss and/or isolation mechanisms for volatiles are critical to these models; hydrodynamic escape was not a dominant process, but loss of a nascent lunar atmosphere or separation of condensates into a proto-lunar crust are possible mechanisms by which volatiles could be separated from the lunar interior. The results do not preclude models that suggest a lunar volatile depletion episode related to the Giant Impact. Conversely, LMO models for volatile loss do not require loss of volatiles prior to lunar formation. Outgassing during planetary magma ocean phases likely played a profound role in setting the volatile inventories of planets, particularly for low mass bodies that experienced the greatest volatile loss. In turn, our results suggest that the initial compositions of planets that accreted from smaller, highly differentiated planetesimals were likely to be severely volatile depleted. (C) 2017 Elsevier Inc. All rights reserved.