Highly-Expressed MiR-221-3p Distinctly Increases the Incidence of Diabetic Retinopathy in Patients With Type 2 Diabetes Mellitus.

Objective: Diabetic retinopathy (DR) is the leading cause of blindness in patients with diabetes mellitus (DM). MiR-221-3p is implicated in microvascular dysfunction in DR, and we explored their relationship. Methods: Patients with type 2 diabetes mellitus (T2DM) were allocated to the non-DR (NDR)/nonproliferative DR (NPDR)/proliferative DR (PDR) groups, with their clinical baseline and pathological data collected. The miR-221-3p and VEGF levels were determined by reverse transcription quantitative polymerase chain reaction (RT-qPCR) and ELISA, respectively. Peripheral blood endothelial progenitor cell (EPC) and endothelial cell (EC) ratios were ascertained by flow cytometry. The correlations between miR-221-3p levels and VEGF/EPCs/ECs, the predictive value of serum miR-221-3p levels in DR, and the independent risk factors for DR occurrence in T2DM were analyzed by Pearson's correlation analysis, receiver operating characteristic (ROC) curve, and multifactorial logistic regression analysis. Results: Serum miR-221-3p was highly expressed in DR. Clinical severity of DR was positively correlated with miR-221-3p levels. Endothelial function was impaired in DR. Serum miR-221-3p levels in DR were favorably correlated with VEGF and ECs and negatively associated with EPCs. The area under the curve of serum miR-221-3p in evaluating DR occurrence in patients with T2DM was 0.8178 (1.235 cutoff value, 69.62% sensitivity, and 82.35% specificity). High expression of miR-221-3p increased DR incidence in patients with T2DM. Diabetes course, VEGF, EPCs, ECs, and miR-221-3p levels were independent risk factors for DR development in patients with T2DM. Conclusions: Serum miR-221-3p levels in patients with DR were positively correlated with VEGF and ECs and negatively linked with EPCs. Highly expressed miR-221-3p distinctly increased DR incidence in patients with T2DM and was an independent risk factor for DR development in patients with T2DM. Translational Relevance: This study assessed serum miR-221-3p level and endothelial function indicators (VEGF, EPCs, and ECs) in patients with DR and analyzed the correlation between each indicator. We found that high serum miR-221-3p expression prominently increased the incidence of DR in patients with T2DM and was an independent risk factor for the development of DR in patients with T2DM. This study provided a scientific basis for further clarification of the pathogenesis of DR, and also provided new ideas for clinical prediction and management of DR.

Effects of grazing intensity on diversity and composition of rhizosphere and non-rhizosphere microbial communities in a desert grassland.

Overgrazing-induced grassland degradation has become a serious ecological problem worldwide. The diversity and composition of soil microbial communities are sensitive to grazing disturbances. However, our understanding is limited with respect to the effects of grazing intensity on bacterial and fungal communities, especially in plant rhizosphere. Using a long-term grazing experiment, we evaluated the diversity and composition of microbial communities in both rhizosphere and non-rhizosphere soils under three grazing intensities (light, moderate, and heavy grazing) in a desert grassland and examined the relative roles of grazing-induced changes in some abiotic and biotic factors in affecting the diversity and composition of microbial communities. Our results showed that soil bacteria differed greatly in diversity and composition between rhizosphere and non-rhizosphere zones, and so did soil fungi. Moderate and heavy grazing significantly reduced the rhizosphere bacterial diversity. Grazing intensity substantially altered the bacterial composition and the fungal composition in both zones but with different mechanisms. While root nitrogen and soil nitrogen played an important role in shaping the rhizosphere bacterial composition, soil-available phosphorus greatly affected the non-rhizosphere bacterial composition and the fungal composition in both soils. This study provides direct experimental evidence that the diversity and composition of microbial communities were severely altered by heavy grazing on a desert grassland. Thus, to restore the grazing-induced, degraded grasslands, we should pay more attention to the conservation of soil microbes in addition to vegetation recovery.

Nitrogen deposition further increases Ambrosia trifida root exudate invasiveness under global warming.

Invasive plants can change the soil ecological environment in the invasion area to adapt to their growth and reproduction through root exudates. Root exudates are the most direct manifestation of plant responses to external environmental changes, but there is a lack of studies on root exudates of invasive plants in the context of inevitable global warming and nitrogen deposition. In this research, we used widely targeted metabolomics to investigate Ambrosia trifida root exudates during seedling and maturity under warming and nitrogen deposition to reveal the possible mechanisms of A. trifida adaptation to climate change. The results showed that the organic acids increased under warming condition but decreased after nitrogen addition in the seedling stage. Phenolic acids increased greatly after nitrogen addition in the mature stage. Most phenolic acids were annotated in the phenylpropane metabolic pathway and tyrosine metabolism. Therefore, nitrogen deposition may increase the adaptability of A. trifida through root exudates, making it more invasive under global warming. The results provide new ideas for preventing and controlling the invasion of A. trifida under climate change.

Mechanism for the restoration of degraded typical steppe by nitrogen and phosphorus co-addition.

The reduction of soil nutrient content is one of the major reasons caused grassland degradation in China. Nutrient addition is thus considered as an effective measure for the restoration of degraded grasslands. However, over-fertilization can lead to decrease in plant diversity. To clarify the appropriate amount of nutrient addition and the underlying mechanism that promotes grassland restoration, we set up a nitrogen and phosphorus co-addition experiment in a degraded typical steppe of Inner Mongolia, and examined the responses at community, functional group and species levels to nutrient addition. The results showed that nutrient addition enhanced biomass while did not reduce species richness at the community level. The biomass showed a saturation response with the increases of nutrient addition, which approached saturation under the 12.0 g N·m-2, 3.8 g P·m-2 treatment. Species richness increased significantly under the lower nutrient treatments (N <9.6 g·m-2, P < 3.0 g·m-2) compared with the control, while the two high nutrient treatments did not alter species richness. At the functional group level, biomass and abundance of perennial rhizome grasses increased significantly with the increases of nutrient addition levels. Biomass and density of annuals increased significantly under high nutrient addition levels. However, the abundance and biomass of perennial bunchgrasses and perennial forbs were rarely affected. At the species level, six target species responded differently to nutrient addition. Biomass of Leymus chinensis was significantly increased due to the increase of population density and individual biomass. Biomass of Stipa grandis, Agropyron cristatum and Cleistogenes squarrosa change little. Biomass of Potentilla acaulis and Carex korshinskyi were reduced due to the decreases in individual biomass and population density, respectively. As a measure of restoring degraded grassland, nutrient addition could significantly increase biomass and species diversity, decrease biomass of the degradation indicator species, and increase biomass of perennial rhizomes grasses.

Positive legacies of severe droughts in the Inner Mongolia grassland.

Global change-induced extreme droughts are increasing in grasslands worldwide, and drought legacies may greatly affect the responses of grassland ecosystems to these changes. However, it remains poorly understood whether and how severe droughts have a positive legacy effect on grassland productivity. By combining a 4-year precipitation manipulation experiment with a 40-year observational study in a semiarid grassland, we showed that extreme droughts could create strong positive legacies on community productivity and that such legacies could last for multiple years. The mechanism behind this was the coupled effect of the drought-induced increase in annuals and the favorable precipitation pattern that facilitated the flourishing of annuals in subsequent years. This study provides experimental and observational evidence for positive drought legacies and reveals their underlying mechanisms. Our findings suggest that positive drought legacies should be incorporated into Earth system models to better predict the impact of extreme droughts on grassland ecosystems.

Mobility loss and its restoration in China grasslands.

Loss of mobility in rangeland use has emerged as a dominant theory to explain ecosystem degradation in the research area of rangeland ecology. The loss of mobility in rangeland use in China resulted from multiple interacting natural and social factors as well as policy changes. Re-establi-shing mobility in rangeland use is critical to rangeland restoration and sustainable management in China. However, the recovery of rangeland might be difficult through simply reverting to traditional rotational grazing. Alternatively, we explored various state-of-the-art rangeland management techniques, including smart fence, intelligent wearables for livestock, and rapid forage biomass measurement using drones. Such novel rangeland management techniques could be used in different regions with different climate and vegetation in China to re-establish mobility in rangeland utilization. Paired with these advanced techniques, new rotational high-mobility grazing systems could further integrate with other essential measures of grass-livestock husbandry in China, such as balancing of forage production and livestock grazing, supplemental forage of livestock, and replenishment of soil nutrients in rangeland. All these practices would ensure a more sustainable and effective utilization of rangeland in China.

Spatiotemporal patterns and drivers of methane uptake across a climate transect in Inner Mongolia Steppe.

Steppe soils are important biological sinks for atmospheric methane (CH4), but the strength of CH4 uptake remains uncertain due to large spatiotemporal variation and the lack of in situ measurements at regional scale. Here, we report the seasonal and spatial patterns of CH4 uptake across a 1200 km transect in arid and semi-arid steppe ecosystems in Inner Mongolia, ranging from meadow steppe in the east plain to typical and desert steppes on the west plateau. In general, seasonal patterns of CH4 uptake were site specific, with unimodal seasonal curves in meadow and typical steppes and a decreasing seasonal trend in desert steppe. Soil moisture was the dominant factor explaining the seasonal patterns of CH4 uptake, and CH4 uptake rate decreased with an increase in soil moisture. Across the transect, CH4 uptake showed a skewed unimodal spatial pattern, with the peak rate observed in the typical steppe sites and with generally higher uptake rates in the west plateau than in the east plain. Soil moisture, together with soil temperature, soil total carbon, and aboveground plant biomass, were the main drivers of the regional patterns of CH4 uptake rate. These findings are important for model development to more precisely estimate the soil CH4 sink capacity in arid and semi-arid regions.

Resource Reallocation of Two Grass Species During Regrowth After Defoliation.

Defoliation is widely used for grassland management. Our understanding of how grass species adjust their regrowth and regain balance after defoliation remains limited. In the present study, we examined the regrowth processes of two dominant species after defoliation in grasslands in Inner Mongolia. Our results showed that the aboveground biomass and total biomass of both species significantly decreased and did not completely recover to the control level after 30 days of regrowth. The leaf mass ratio of Leymus chinensis reached the control level at 15 days, but that of Stipa grandis did not recover to the control level. The root mass ratio of these species reached the same levels as that of the control plants within 10 days after defoliation. As indicated by the dynamics of water-soluble carbohydrates (WSCs), protein, and biomass-based shoot: root ratios, both species regained balances of WSCs and protein between above- and below-ground organs at day 10 after defoliation; however, the biomass regained balance 15 days after defoliation. We deduced that the biomass-based shoot:root ratio was regulated by the WSCs and protein concentrations. In conclusion, following defoliation, both grass species first restore their nutrient-based balance between above- and below-ground parts and then regain biomass balance.

Climate variability decreases species richness and community stability in a temperate grassland.

Climate change involves modifications in both the mean and the variability of temperature and precipitation. According to global warming projections, both the magnitude and the frequency of extreme weather events are increasing, thereby increasing climate variability. The previous studies have reported that climate warming tends to decrease biodiversity and the temporal stability of community primary productivity (i.e., community stability), but the effects of the variability of temperature and precipitation on biodiversity, community stability, and their relationship have not been clearly explored. We used a long-term (from 1982 to 2014) field data set from a temperate grassland in northern China to explore the effects of the variability of mean temperature and total precipitation on species richness, community stability, and their relationship. Results showed that species richness promoted community stability through increases in asynchronous dynamics across species (i.e., species asynchrony). Both species richness and species asynchrony were positively associated with the residuals of community stability after controlling for its dependence on the variability of mean temperature and total precipitation. Furthermore, the variability of mean temperature reduced species richness, while the variability of total precipitation decreased species asynchrony and community stability. Overall, the present study revealed that species richness and species asynchrony promoted community stability, but increased climate variability may erode these positive effects and thereby threaten community stability.

Scale dependence of the diversity-stability relationship in a temperate grassland.

A positive relationship between biodiversity and ecosystem stability has been reported in many ecosystems; however, it has yet to be determined whether and how spatial scale affects this relationship. Here, for the first time, we assessed the effects of alpha, beta and gamma diversity on ecosystem stability and the scale dependence of the slope of the diversity-stability relationship.By employing a long-term (33 years) dataset from a temperate grassland, northern China, we calculated the all possible spatial scales with the complete combination from the basic 1-m2 plots.Species richness was positively associated with ecosystem stability through species asynchrony and overyielding at all spatial scales (1, 2, 3, 4 and 5 m2). Both alpha and beta diversity were positively associated with gamma stability.Moreover, the slope of the diversity-area relationship was significantly higher than that of the stability-area relationship, resulting in a decline of the slope of the diversity-stability relationship with increasing area.Synthesis. With the positive species diversity effect on ecosystem stability from small to large spatial scales, our findings demonstrate the need to maintain a high biodiversity and biotic heterogeneity as insurance against the risks incurred by ecosystems in the face of global environmental changes.

Effects of functional diversity loss on ecosystem functions are influenced by compensation.

Understanding the impacts of biodiversity loss on ecosystem functioning and services has been a central issue in ecology. Experiments in synthetic communities suggest that biodiversity loss may erode a set of ecosystem functions, but studies in natural communities indicate that the effects of biodiversity loss are usually weak and that multiple functions can be sustained by relatively few species. Yet, the mechanisms by which natural ecosystems are able to maintain multiple functions in the face of diversity loss remain poorly understood. With a long-term and large-scale removal experiment in the Inner Mongolian grassland, here we showed that losses of plant functional groups (PFGs) can reduce multiple ecosystem functions, including biomass production, soil NO3 -N use, net ecosystem carbon exchange, gross ecosystem productivity, and ecosystem respiration, but the magnitudes of these effects depended largely on which PFGs were removed. Removing the two dominant PFGs (perennial rhizomatous grasses and perennial bunchgrasses) simultaneously resulted in dramatic declines in all examined functions, but such declines were circumvented when either dominant PFG was present. We identify the major mechanism for this as a compensation effect by which each dominant PFG can mitigate the losses of others. This study provides evidence that compensation ensuing from PFG losses can mitigate their negative consequence, and thus natural communities may be more resilient to biodiversity loss than currently thought if the remaining PFGs have strong compensation capabilities. On the other hand, ecosystems without well-developed compensatory functional diversity may be much more vulnerable to biodiversity loss.

Decreased expression of IL-27 and its correlation with Th1 and Th17 cells in progressive multiple sclerosis.

Progressive multiple sclerosis (MS) is an immune-mediated demyelinating disease in which both imbalanced T helper (Th) subsets and aberrant cytokine profiles have been found. Interleukin-27 (IL-27), a cytokine with pro-inflammatory and anti-inflammatory effects, plays pleiotropic roles in immunomodulation. In the present study, plasma levels of IL-27, interferon-gamma (IFN-γ), IL-17 and frequencies of peripheral Th1, Th17 cells were determined by enzyme-linked immunosorbent assay (ELISA) and flow cytometry in 45 progressive MS and 25 healthy controls. mRNA expression levels of IL-27, IFN-γ, T-bet, IL-17 and RAR-related orphan receptor gamma t (RORγt) in peripheral blood mononuclear cells (PBMCs) were also quantified by real-time polymerase chain reaction. Plasma and mRNA levels of IL-27 in progressive MS patients were significantly lower than those in healthy controls, while plasma concentrations of IL-17, frequencies of circulating Th17, and mRNA expression levels of IL-17 as well as RORγt were all increased remarkably compared with healthy controls. No statistical significance was observed in IFN-γ and T-bet mRNA expression or plasma IFN-γ levels between progressive MS patients and healthy controls. Moreover, plasma levels of IL-27 were found to be negatively correlated to the percentages of circulating Th17 or plasma IL-17 concentrations in patients with progressive MS. Our data showed that progressive MS patients had decreased plasma and mRNA expression levels of IL-27, suggesting that it might be involved in the pathophysiological process of MS.

Hierarchical reproductive allocation and allometry within a perennial bunchgrass after 11 years of nutrient addition.

Bunchgrasses are one of the most important plant functional groups in grassland ecosystems. Reproductive allocation (RA) for a bunchgrass is a hierarchical process; however, how bunchgrasses adjust their RAs along hierarchical levels in response to nutrient addition has never been addressed. Here, utilizing an 11-year nutrient addition experiment, we examined the patterns and variations in RA of Agropyron cristatum at the individual, tiller and spike levels. We evaluated the reproductive allometric relationship at each level by type II regression analysis to determine size-dependent and size-independent effects on plant RA variations. Our results indicate that the proportion of reproductive individuals in A. cristatum increased significantly after 11 years of nutrient addition. Adjustments in RA in A. cristatum were mainly occurred at the individual and tiller levels but not at the spike level. A size-dependent effect was a dominant mechanism underlying the changes in plant RA at both individual and tiller levels. Likewise, the distribution of plant size was markedly changed with large individuals increasing after nutrient addition. Tiller-level RA may be a limiting factor for the adjustment of RA in A. cristatum. To the best of our knowledge, this study is the first to examine plant responses in terms of reproductive allocation and allometry to nutrient enrichment within a bunchgrass population from a hierarchical view. Our findings have important implications for understanding the mechanisms underlying bunchgrass responses in RA to future eutrophication due to human activities. In addition, we developed a hierarchical analysis method for disentangling the mechanisms that lead to variation in RA for perennial bunchgrasses.

Nitrogen and water availability interact to affect leaf stoichiometry in a semi-arid grassland.

The effects of global change factors on the stoichiometric composition of green and senesced plant tissues are critical determinants of ecosystem feedbacks to anthropogenic-driven global change. So far, little is known about species stoichiometric responses to these changes. We conducted a manipulative field experiment with nitrogen (N; 17.5 g m(-2) year(-1)) and water addition (180 mm per growing season) in a temperate steppe of northern China that is potentially highly vulnerable to global change. A unique and important outcome of our study is that water availability modulated plant nutritional and stoichiometric responses to increased N availability. N addition significantly reduced C:N ratios and increased N:P ratios but only under ambient water conditions. Under increased water supply, N addition had no effect on C:N ratios in green and senesced leaves and N:P ratios in senesced leaves, and significantly decreased C:P ratios in both green and senesced leaves and N:P ratios in green leaves. Stoichiometric ratios varied greatly among species. Our results suggest that N and water addition and species identity can affect stoichiometric ratios of both green and senesced tissues through direct and interactive means. Our findings highlight the importance of water availability in modulating stoichiometric responses of plants to potentially increased N availability in semi-arid grasslands.

Hierarchical plant responses and diversity loss after nitrogen addition: testing three functionally-based hypotheses in the Inner Mongolia grassland.

BACKGROUND: Numerous studies have shown that nitrogen (N) deposition decreases biodiversity in terrestrial ecosystems. To explain the N-induced species loss, three functionally based hypotheses have been proposed: the aboveground competition hypothesis, the belowground competition hypothesis, and the total competition hypothesis. However, none of them is supported sufficiently by field experiments. A main challenge to testing these hypotheses is to ascertain the role of shoot and root competition in controlling plant responses to N enrichment. Simultaneously examining both aboveground and belowground responses in natural ecosystems is logistically complex, and has rarely been done. METHODOLOGY/PRINCIPAL FINDINGS: In a two-year N addition experiment conducted in a natural grassland ecosystem, we investigated both above- and belowground responses of plants at the individual, species, and community levels. Plants differed significantly in their responses to N addition across the different organizational levels. The community-level species loss was mainly due to the loss of perennial grasses and forbs, while the relative abundance of plant species was dependent mainly on individual-level responses. Plasticity in biomass allocation was much smaller within a species than between species, providing a biological basis for explaining the functionally based species loss. All species increased biomass allocation to aboveground parts, but species with high belowground allocations were replaced by those with high aboveground allocations, indicating that the increased aboveground competition was the key process responsible for the observed diversity loss after N addition in this grassland ecosystem. CONCLUSIONS/SIGNIFICANCE: Our findings shed new light on the validity of the three competing hypotheses concerning species loss in response to N enrichment. They also have important implications for predicting the future impacts of N deposition on the structure and functioning of terrestrial ecosystems. In addition, we have developed a new technique for ascertaining the roles of aboveground and belowground competition in determining plant responses to N fertilization.

Overaccumulation of transforming growth factor-beta1 and basic fibroblast growth factor in lens epithelial cells of congenital cataract.

OBJECTIVE: The aim of this study was to evaluate the accumulation of transforming growth factor (TGF)-beta1 and basic fibroblast growth factor (bFGF) at gene and protein levels in lens epithelial cells of anterior subcapsular congenital cataracts (ASCC). DESIGN: Case-control study and analysis. PARTICIPANTS: Twenty-six eyes with ASCC were studied, and 14 eyes with transparent lenses were used as controls. METHODS: Anterior epithelium capsules with ASCC were obtained from patients who had undergone extracapsular cataract extraction. The accumulation of TGF-beta1 and bFGF gene and protein was determined by reverse transcription-real time polymerase chain reaction (RT-PCR) and Western blotting. RESULTS: The results from RT-PCR showed that the accumulation of TGF-beta1 and bFGF mRNA in lens epithelial cells of ASCC was significantly higher compared with controls in both male and female samples. Furthermore, there was a positive correlation between the accumulation of bFGF mRNA and TGF-beta1 mRNA. Western blotting results demonstrated that the accumulation of TGFbeta1 and bFGF proteins in lens epithelial cells with ASCC was also highly elevated. CONCLUSIONS: The overaccumulation of TGF-beta1 and bFGF in lens epithelial cells may play an important role in the formation of subcapsular congenital cataract.

Primary production and rain use efficiency across a precipitation gradient on the Mongolia Plateau.

Understanding how the aboveground net primary production (ANPP) of arid and semiarid ecosystems of the world responds to variations in precipitation is crucial for assessing the impacts of climate change on terrestrial ecosystems. Rain-use efficiency (RUE) is an important measure for acquiring this understanding. However, little is known about the response pattern of RUE for the largest contiguous natural grassland region of the world, the Eurasian Steppe. Here we investigated the spatial and temporal patterns of ANPP and RUE and their key driving factors based on a long-term data set from 21 natural arid and semiarid ecosystem sites across the Inner Mongolia steppe region in northern China. Our results showed that, with increasing mean annual precipitation (MAP), (1) ANPP increased while the interannual variability of ANPP declined, (2) plant species richness increased and the relative abundance of key functional groups shifted predictably, and (3) RUE increased in space across different ecosystems but decreased with increasing annual precipitation within a given ecosystem. These results clearly indicate that the patterns of both ANPP and RUE are scale dependent, and the seemingly conflicting patterns of RUE in space vs. time suggest distinctive underlying mechanisms, involving interactions among precipitation, soil N, and biotic factors. Also, while our results supported the existence of a common maximum RUE, they also indicated that its value could be substantially increased by altering resource availability, such as adding nitrogen. Our findings have important implications for understanding and predicting ecological impacts of global climate change and for management practices in arid and semiarid ecosystems in the Inner Mongolia steppe region and beyond.

Long-term impacts of land-use change on dynamics of tropical soil carbon and nitrogen pools.

Land-use changes, especially the conversion of native forest vegetation to cropland and plantations in tropical region, can alter soil C and N pools and N availability for plant uptake. Deforestation, followed by shifting cultivation and establishment of rubber tree plantation, is a common land-use change in Xishuangbanna, southwest China. However the influence of this kind of land-use change on soil C and N dynamics in this region remains poorly understood. This study was conducted to assess the effects of land-use change on soil C and N pools. Soil samples were collected on five adjacent plots, which belong to three land-use types including secondary forest-an acuminate banana (Musa itinerans) secondary forest and a male bamboo (Dendrocalamus membranaceae) secondary forest, shifting cultivation, and rubber tree (Hevea brasiliensis (H. B. K.) Muell. Arg.) plantation (one plot is 3-year-old, and another is 7-year-old). We measured soil bulk density (BD), pH value, moisture content and concentrations of soil organic carbon (SOC), total soil nitrogen (TSN), and inorganic N (NO3- -N and NH4+ -N) at 0-3, 3-20, 20-40 and 40-60 cm depths, and calculated C and N pools in 0-20, 20-40, 40-60, and 0-60 cm soil layers. Compared with the adjacent secondary forests, shifting cultivation and establishment of rubber tree plantations resulted in significant decline in concentrations and stocks of SOC and TSN in 0-20 and 0-60 cm soil layers, and increase in pH and bulk density at 0-3, 3-20, and 20-40 cm depths. Soil moisture content decreased only in 0-20 cm surface soils in shifting cultivation and plantations. The dynamics of mineral N was much more complex, which had different trends among depths and ecosystems. Compared with the secondary forests, SOC stocks in 0-20 cm surface soils in shifting cultivation and rubber tree plantations (3-year-old plantation and 7-year-old plantation) decreased by 34.0%, 33%, and 23%; and TSN stocks decreased by 32.2%, 20.4%, and 20.4%, respectively, whereas the decreases of SOC and TSN stocks in 0-60 cm soil layers were much less. The results indicated that C and N losses were mainly occurred in 0-20 cm surface soil, followed by 20-40 cm layer.

Biogenic VOCs emission inventory development of temperate grassland vegetation in Xilin River basin, Inner Mongolia, China.

Given the key role of biogenic volatile organic compounds (VOCs) to tropospheric chemistry and regional air quality, it is important to generate accurate VOCs emission inventories. However, only a less fraction of plant species, in temperate grassland of Inner Mongolia, has been characterized by quantitative measurements. A taxonomic methodology, which assigns VOCs measurements to unmeasured species, is an applicable and inexpensive alternation for extensive VOCs emission survey, although data are needed for additional plant families and genera to further validate the taxonomic approach in grassland vegetation. In this experiment, VOCs emission rates of 178 plant species were measured with a portable photoionization detector (PID). The results showed the most of genera and some families have consistent feature of their VOCs emission, especially for isoprene, and provide the basic premise of taxonomic methodology to develop VOCs emission inventories for temperate grassland. Then, the taxonomic methodology was introduced into assigning emission rate to other 96 species, which no measured emission rates available here. A systematical emission inventory of temperate grassland vegetation in Inner Mongolia was provided and further evidence that taxonomy relationship can serve as a useful guide for generalizing the emissions behavior of many, but not all, plant families and genera to grassland vegetation.