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Nitrogen deposition has increased rapidly in eastern China, which can affect the stoichiometric characteristics of plants. However, the effects of N addition on the nitrogen (N) and phosphorous (P) allocation strategies for various plant life forms (e.g. trees, shrubs, and herbs) have rarely been studied. This study evaluated the effects of N addition on N and P stoichiometry and their scaling exponents in the leaves and fine roots of the different life form groups. N and P concentrations in the leaves of shrubs and herbs increased under N addition treatments, whereas tree leaves exhibited a more stable response. In contrast, N addition has no significant effect on N and P concentrations in the fine roots of the three plant life forms. N addition accelerated the allocation of more N and P to the leaves than to the fine roots in all three life forms. Furthermore, the N-P allocation scaling exponents of the leaves and fine roots of the trees were equal to 1.0, indicating an isometric pattern. In contrast, the N-P allocation scaling exponents of shrubs and herbs were less than 1.0, indicating an allometric pattern. Although high N availability promoted shrubs and herbs to distribute P to leaves at a higher proportion than N, only slight effects were detected in tree leaves. These changes in N-P allocation patterns indicate that life forms and N addition levels work together to modulate plants allocation strategies. This suggests the importance of life form categories when evaluating N-P allocation strategies in forest plants.

Measuring plant heights one by one is an important way to explore the height structure of grassland plant communities, and can be used to analyze the universal rules and regional variations of vegetation growth under environmental change. We chose grasslands in three plateaus, namely Tibetan Plateau (TP), Mongolian Plateau (MP) and Loess Plateau (LP), and set up three grassland transects along the precipitation gradients from meadow, steppe to desert. The mean height of grassland vegetation was 30.38 ± 22.44 cm, and the mean height from TP, MP to LP increased significantly. The aggregation of grassland vegetation exhibited a positive skew distribution (0.91, 3.60), and the community aggregation from TP, MP to LP tended to a normal distribution (0, 3). However, for TP, there was an exponential distribution in community aggregation of meadows, and a uniform distribution in that of desert. The explanatory effect of climate and soil nutrients on the variation of mean height in each region was more than 70%, while the explanatory effect on the community aggregation was the highest at TP, only 29%. From TP, MP to LP, response intensity of mean height to environmental changes increased significantly, and the influence of temperature and precipitation gradually increased, the influence of radiation, wind speed, and nutrients gradually weakened, and the synergy among environmental factors strengthened. Our study shows that normal distribution is a universal rule of grassland height construction, and that the synergy of environmental factors varies from region to region.

BACKGROUND: Acute kidney injury (AKI) and renal replacement therapy (RRT) are common after heart transplantation (HT). The need for RRT has been reported to be one of the most important predictors of a poor prognosis after HT. Therefore, it is important to early identify risk factors of RRT after HT. However, in the heart transplantation setting, the risk factors are less well studied, and some of the conclusions are controversial. This study aimed to identify the clinical predictors of RRT after HT. METHODS: This single-center, retrospective study from January 2010 to June 2021 analyzed risk factors (pre-, intra-, and postoperative characteristics) of 163 patients who underwent HT. The endpoint of the study was RRT within 7 days of HT. Risk factors were analyzed by multivariable logistic regression models. RESULTS: Fifty-five (33.74%) recipients required RRT within 7 days of HT. Factors independently associated with RRT after HT were as follows: a baseline estimated glomerular filtration rate (eGFR) 10 mg/kg (OR =3.197; 95% CI: 1.290–7.923; P=0.012), the use of mechanical circulatory support (MCS) during surgery (OR =4.903; 95% CI: 1.628–14.766; P=0.005), a cardiopulmonary bypass (CPB) time ≥5 hours (OR =3.929; 95% CI: 1.222–12.634; P=0.022), and postoperative serum total bilirubin (TBIL) ≥60 umol/L (OR =5.105; 95% CI: 1.868–13.952; P=0.001). Protective factors were higher postoperative serum albumin (OR =0.907; 95% CI: 0.837–0.983; P=0.017) and higher postoperative left ventricular ejection fraction (LVEF) (OR =0.908; 95% CI: 0.838–0.985; P=0.020). CONCLUSIONS: A low preoperative eGFR, a high intraoperative dose of methylprednisolone, a long CPB time, the use of mechanical circulatory support, and a high postoperative TBIL were risk factors for RRT after HT. While a high postoperative serum albumin level and a high left ventricular ejection fraction were protective factors. Understanding these risk factors may help us identify high-risk patients and intervene early.

Evidence-based selective cutting at prescribed intervals as part of good forest management can enhance the carbon sequestration capacity of the forest. The effect of forest management on carbon sequestration has, however, not been quantified. Thus, carbon content of various organs was measured for 323 tree species, 247 shrub species, and 233 herb species in seven temperate coniferous and broad-leaved mixed forests that were subjected to selective cutting with restoration durations of 100, 55, 45, 36, 25, 14, and 6 years to explore dynamic changes in carbon storage. The results showed that biomass carbon allocation in different organs followed a pattern: trunk > root > branch > leaf for all forests. With longer restoration durations, more carbon accumulated in different organs and in soils. Interestingly, when the restoration duration exceeded 50 years, carbon storage in ecosystem was larger than that in primary forests with 100-year cutting intervals, suggesting that a reasonable selective cutting interval can increase forest carbon sequestration. Mean diameter at breast height (DBH) and forest carbon storage were significantly positively correlated, and carbon storage of selectively cut forests exceeded that of primary forests when the stand mean DBH exceeded 15.66 cm. Therefore, mean DBH of forests can be an indicator for combining sustainable forest management and forest carbon sequestration. Additionally, the classic coefficients of 0.45 and 0.50 used to estimate carbon sequestration underestimated values by 2.65% and overestimated by 8.16%, respectively, in comparison with the measured carbon content from different plant organs.

Stomata control carbon and water vapor exchange between the leaves and the atmosphere, thus influencing photosynthesis and transpiration. Combinations of forest patches with different stand ages are common in nature, however, information of which stomatal traits vary among these stands and how, remains limited. Here, seven different aged forest stands (6, 14, 25, 36, 45, 55, and 100 years) were selected in typical temperate, mixed broadleaf-conifer forests of northeast China. Stomatal density, size and relative area of 624 species, including the same species in stands of different ages were selected. Stomatal density, size and relative area were distributed log-normally, differing across all species and plant functional groups. Stomatal density ranged from 4.2 to 1276.7 stomata mm–2, stomatal size ranged from 66.6 to 8315.7 μm2, and stomatal relative area 0.1–93.3%. There was a significant negative relationship between density and size at the species and functional group levels, while the relative stomatal area was positively correlated with density and size. Stomatal traits of dominant species were relatively stable across different stand ages but were significantly different for herbs. The results suggest that stomatal traits remain relatively stable for dominant species in natural forests and therefore, spatial variation in stomatal traits across forest patches does not need to be incorporated in future ecological models.

The stomata control carbon and water vapor exchange between the leaves and atmosphere and may reflect plant adaptation to climate change to some extent. However, the spatial variation of stomatal traits on different sides of the leaves’ epidermis and their response to environmental changes remain unclear. Here, we measured stomatal density (SD), stomatal size (SS), and stomatal relative area (SRA) on both leaf surfaces of 181 plant species across an environmental gradient on the Loess Plateau. We calculated the proportion of stomatal traits between different epidermis surfaces of the leaves (abaxial and adaxial) and measured the total SD (SDtot), total SS (SStot), and total SRA (SRAtot) of the leaves as a whole. The SDtot, SStot, and SRAtot showed a log-normal distribution, differing across grassland types and plant functional groups, with a range of 22.57–890.09 stomata mm−2, 84.61–2022.81 μm2, and 0.51–43.71%, respectively. The SDtot, SStot, and SRAtot differed significantly between different grassland types. Meadow plants had larger SDtot, desert plants had larger SStot, and typical grassland plants had relatively larger SRAtot. The abaxial SD and SRA of the woody plants were significantly higher than those of herbaceous plants, but no significant differences were observed at the adaxial surface or for the overall leaf. A higher SDtot was correlated with a larger stomatal density ratio (R.SD) and smaller stomatal size ratio (R.SS). The R.SD, abaxial SD, abaxial SS, and adaxial SS were significantly correlated with environmental factors, but no such correlations were observed for the adaxial SD. These findings highlight the strong associations of stomatal traits with plant functional group and climate at a regional scale, representing the climatic adaptation strategies of stomatal traits across natural grassland communities.

Plants often adjust their leaf mitochondrial ("dark") respiration (Rd ) measured at a standardized temperature such as 20°C (R20 ) downward after experiencing warmer temperatures and upward after experiencing cooler temperatures. These responses may help leaves maintain advantageous photosynthetic capacity and/or be a response to recent photosynthate accumulation, and can occur within days after a change in thermal regime. It is not clear, however, how the sensitivity and magnitude of this response change over time, or which time period prior to a given measurement best predicts R20 . Nor is it known whether nighttime, daytime, or 24-hour temperatures should be most influential. To address these issues, we used data from 1620 Rd temperature response curves of 10 temperate and boreal tree species in a long-term field experiment in Minnesota, USA to assess how the observed nearly complete acclimation of R20 was related to past temperatures during periods of differing lengths. We hypothesized that R20 would be best related to prior midday temperatures associated with both photosynthetic biochemistry and peak carbon uptake rates that drive carbohydrate accumulation. Inconsistent with this hypothesis, prior night temperatures were the best predictors of R20 for all species. We had also hypothesized that recent (prior 3-10 days) temperatures should best predict R20 because they likely have stronger residual impacts on leaf-level physiology than periods extending further back in time, whereas a prior 1- to 2-day period might be a span shorter than one to which photosynthetic capacity and Rd adjust. There was little to no support for this idea, as for angiosperms, long time windows (prior 30-60 nights) were the best predictors, while for gymnosperms both near-term (prior 3-8 nights for pines, prior 10-14 nights for spruce/fir) and longer-term periods (prior 45 nights) were the best predictors. The importance of nighttime temperatures, the relatively long "time-averaging" that best explained acclimation, and dual peaks of temporal acclimation responsiveness in some species were all results that were unanticipated.

Regional differences and regulatory mechanisms of vegetation productivity response to changing environmental conditions constitute a core issue in macroecological researches. To verify the main limiting factors of different macrosystems [temperature-limited Tibetan Plateau (TP), precipitation-limited Mongolian Plateau (MP), and nutrient-limited Loess Plateau (LP)], we conducted a comparative survey of the east-west grassland transects on the three plateaus and explored the factors limiting regional productivity and their underlying mechanisms. The results showed that aboveground net primary productivity (ANPP) of LP (109.10 ± 16.76 g m-2 yr-1) was significantly higher than that of MP (66.71 ± 11.11 g m-2 yr-1) and TP (57.02 ± 10.59 g m-2 yr-1). The response rate of ANPP with environmental changes was different among different plateaus, being closely related to the main limiting factors. On MP, this was precipitation, on LP it was temperature and nutrients, and on TP, it was non-specific, reflecting restriction by the extremely low temperature. After autocorrelation screening of environmental factors, different regions exhibited different productivity response mechanisms. MP was mainly influenced by temperature and precipitation, LP was influenced by temperature and nutrient, and TP was influenced by nutrient, reflecting the modifying effect of the main limiting factors. The effect of each regional environment on ANPP was 72.56% on average and only 27.18% after simple regional integration. The regional model could optimize the simulation error of the integrated model, and the relative deviations in MP, LP, and TP were reduced by 31.76%, 17.22%, and 2.23%, respectively. These findings indicate that the grasslands on the three plateaus may have different or even the opposite mechanisms to control productivity.

To study the response of Pinus tabulaeformis Carrière, an endemic species in China, to N deposition and the adaptive mechanisms involved, the leaves and fine roots functional traits and N:P stoichiometry of Beijing provenances seeding (BY), Shanxi provenances seeding (SY), and Inner Mongolia provenances seeding (NY) were investigated in the this study. Five levels of artificial N addition were applied to seedlings of different provenance for 3 years. Our results showed that, at high-N levels, the specific leaf area of SY plants decreased significantly, while leaf weight ratio increased, which indicated that SY plants have higher light and nutrient absorption capacity under high-N deposition. Leaf total N, leaf N:P ratio, root total N, and root N:P ratio of BY plants increased at medium-N levels, indicating that properly N addition promoted the accumulation of N in BY plants, while N absorption in SY and NY plants was inhibited. Furthermore, N addition promoted the accumulation of P in SY leaves and fine roots. From the adaptation mechanism of P. tabulaeformis, N addition promoted the utilization of nutrients in BY fine roots, which was conducive to the growth of underground parts and the accumulation of biomass. These results also showed that BY plants had adapted to low-N environments. At the same time, P investment in SY leaves and fine roots increased in high-N environments to meet the demands of growth, which also demonstrated adaptation to high-N environments. Owing to the differences in the adaptation mechanism of plants to the environment, the adaptation strategies of P. tabulaeformis of different provenances was significantly different under different nitrogen depositions. This study further provides theoretical foundation for plantation management and vegetation restoration. Keywords: Pinus tabulaeformis Carrière, N addition, Leaves, Fine roots, N:P stoichiometry

Leaf chlorophyll is essential to harvest light energy to drive photosynthesis. Yet, most of studies of leaf chlorophyll concentration (Chl) have typically been limited to few species or sites, and there has been little understanding of its variation among species of contrasting environments, or across forests differing in gross primary productivity (GPP). We measured mass-based foliar Chl concentrations (Chl a, Chl b, and total Chl) for 937 species of nine Chinese forests ranging from tropical to cold-temperate regions. Total Chl varied by over ten-fold from 1.45 to 19.2 mg g−1 (mean: 5.54 mg g−1), and differed among plant functional groups. At the community level, total Chl decreased with increasing latitude. The ratio of Chl a/b decreased from trees to shrubs to herbs, consistent with adaptation to contrasting irradiance, i.e., overstory vs. understory. Total Chl was positively related to leaf N and P concentrations, as would be expected to optimize photosynthesis and carbon fixation. Across forests, GPP was positively correlated with community-averaged Chl (r = 0.57; P

The emerging concept of plant community traits offers a promising tool for explaining the variations in forest productivity. We measured the leaf thickness (LT), leaf area (LA), specific leaf area (SLA), and leaf dry matter content (LDMC) of 234 plant species from seven adjacent Korean pine and broad-leaved mixed forests in Northeast China, which varied in restoration time after selective logging (6, 14, 25, 36, 45, 55, and 100 years). Four leaf traits varied significantly at the species, plant functional group, and community scales. At the community level, LA, SLA, and LDMC followed a significant quadratic trend along the chronological sequence of restoration after selective logging, whereas LT showed no significant variation with time. Interestingly, plant community traits (LT, LA, and SLA) were significantly positively correlated with aboveground net primary productivity (ANPP). Furthermore, plant community traits, restoration time, species diversity, and soil nutrients could jointly explain 78% of the ANPP variation. These findings highlight that the variation in community traits of leaves may play an important role in determining the spatial variation of ANPP in temperate broadleaf-conifer mixed forests. These findings further demonstrate the close linkages between plant community traits and productivity and offer a theoretical basis for incorporating these community traits into future ecological models.

Leaf anatomical traits may reflect plants adaption to environmental changes and influence ecosystem functions, as they regulate light absorption and gas exchange to some extent. Here, we hypothesized that leaf anatomical traits were closely related to gross primary productivity (GPP) because photosynthesis commonly occurs in the chloroplasts of palisade and spongy tissues in leaf. Eight leaf anatomical traits were measured in 916 plant species inhabiting from tropical to cold-temperate forests in eastern China: adaxial epidermis thickness (AD), abaxial epidermis thickness (AB), leaf thickness (LT), palisade tissue thickness (PT), and spongy tissue thickness (ST), palisade–spongy tissue ratio (PT/ST), palisade tissue–leaf thickness ratio (PT/LT), and spongy tissue–leaf thickness ratio (ST/LT). Leaf anatomical traits showed significant latitudinal patterns at species, plant functional group (PFG), and community levels (p

The relationship between plants and the environment is a core area of research in ecology. Owing to differences in plant sensitivity to the environment at different life history stages, the adaptive strategies of plants are a cumulative result of both their life history and environment. Previous research on plant adaptation strategies has focused on adult plants, neglecting saplings or seedlings, which are more sensitive to the environment and largely affect the growth strategy of subsequent life stages. We compared leaf N and P stoichiometric traits of the seedlings, saplings, and adult trees of Acer mono Maxim and different altitudes and found significant linear trends for both life history stages and altitude. Leaf N and P content by unit mass were greatly affected by environmental change, and the leaf N and P content by unit area varied greatly by life history stage. Acer mono leaf N‐P utilization showed a significant allometric growth trend in all life history stages and at low altitudes. The adult stage had higher N‐use efficiency than the seedling stage and exhibited an isometric growth trend at high altitudes. The N‐P utilization strategies of A. mono leaves are affected by changing environmental conditions, but their response is further dependent upon the life history stage of the plant. Thus, this study provides novel insights into the nutrient use strategies of A. mono and how they respond to the environmental temperature, soil moisture content along altitude and how these changes differ among different life history stages, which further provide the scientific basis for the study of plant nutrient utilization strategy on regional scale., The researchers investigated leaf nutrient utilization strategies during the seedling, sapling, and adult stages of A. mono under different moisture and temperature conditions.

BACKGROUND: The objective of this study was to assess postintervention patency and analyze the predictive factors associated with early and late restenosis after intervention in hemodialysis arteriovenous fistulas (AVF) and arteriovenous grafts (AVG). METHODS: This study retrospectively analyzed 284 hemodialysis patients who underwent percutaneous transluminal angioplasty (PTA) due to AVF and AVG stenosis. A total of 350 PTA procedures were performed. Clinical, anatomical, biochemical, and technical variables were analyzed. Using univariate and multivariate analyses, we assessed the postintervention patency of PTA by follow-up, and identified the predictive factors taking into account competing risks. RESULTS: Postintervention patency rates at 3, 6, 12, and 24 months were 86.5%, 66.4%, 42.6%, and 29.8%, respectively, with a median patency duration of 11±0.71 months. Kaplan-Meier analysis showed that the patency rate of the AVF group (n=271) was dramatically higher than the AVG group (n=79) at 3, 6, and 12 months after PTA, respectively (88.9% vs. 78.5%, 69.0% vs. 57.4%, 48.8% vs. 20.0%, P

Most vascular plants acclimate respiration to changes in ambient temperature, but explicit tests of these responses in field settings are rare, and how acclimation responses vary in space and time is relatively unstudied, hindering our ability to predict respiratory release of carbon under future climatic conditions. We measured temperature response curves of leaf respiration for three deciduous tree species from 2009 to 2012 in a field warming experiment (+3.4 °C above ambient) in both open and understory conditions at two sites in the southern boreal forest in Minnesota, USA. We analyzed the effects of warming on leaf respiration, and how the effects varied among species, times of season (early, middle and late parts of the growing season), sites, habitats (understory, open) and years. We hypothesized that the respiration exponent (Q10) of the short-term temperature response curve and the degree of acclimation would be smaller under conditions where plants were more likely to be substrate limited, such as in the understory or the margins of the growing season. However, in contrast to these predictions, stable Q10 and strong respiratory acclimation were consistently observed. For each species, the Q10 did not vary with experimental warming, nor was its response to warming influenced by time of season, year, site or habitat. Strong leaf respiratory acclimation to warming occurred in each species and was consistent across most sources of variation. Most of the leaf traits studied were not affected by warming, while the Q10-leaf nitrogen and R25-soluble carbohydrate relationships were observed, and shifted with warming, implying that acclimation may be associated with the adjustment in respiratory capacity and its relation to leaf nitrogen and soluble carbohydrate content. Consistent Q10 and acclimation across habitats, sites, times of season and years suggest that modeling of temperature acclimation may be possible with relatively simple functions.

Leaf caloric value (LCV) is a useful index to represent the conversion efficiency of leaves for solar energy. We investigated the spatial pattern of LCV and explored the factors (phylogeny, climate, and soil) that influence them at a large scale by determining LCV standardized by leaf area in 920 plant species from nine forest communities along the 3700 km North-South Transect of Eastern China. LCV ranged from 0.024 to 1.056 kJ cm−2 with an average of 0.151 kJ cm−2. LCV declined linearly with increasing latitude along the transect. Altogether, 57.29% of the total variation in LCV was explained by phylogenetic group (44.03% of variation), climate (1.27%), soil (0.02%) and their interacting effects. Significant phylogenetic signals in LCV were observed not only within forest communities but also across the whole transect. This phylogenetic signal was higher at higher latitudes, reflecting latitudinal change in the species composition of forest communities from complex to simple. We inferred that climate influences the spatial pattern of LCV through directly regulating the species composition of plant communities, since most plant species might tolerate only a limited temperature range. Our findings provide new insights into the adaptive mechanisms in plant traits in future studies.

Leaf caloric value (LCV) reflects the capacity of a leaf to fix and accumulate solar energy through photosynthesis. We systematically investigated the LCV of 745 plant species in 9 forests, representing a range of tropical to cold-temperate forests along the 4700-km North-South Transect of Eastern China. The goals were to explore the latitudinal patterns of LCV at the levels of species, plant functional group, and community and to establish the relationship between LCV and gross primary productivity (GPP). Our results showed that LCV for all species ranged from 12.85 to 22.15 KJ g–1 with an average of 18.46 KJ g–1. Plant functional groups had a significant influence on LCV, with trees > shrubs > herbs, conifers > broadleaved trees, and evergreens > deciduous trees. The different values of LCV represented the long-term evolution and adaptation of plant species to different environments. Unexpectedly, no apparent latitudinal trends of LCV at community level were observed, although LCV at the species level clearly decreased with increasing latitude. Use efficiency of LCV (CUE, gC KJ–1), defined as the ratio of GPP to total LCV at the community level, varied quadratic with latitude and was lower in the middle latitudes. Climate (temperature and precipitation) may explain 52.9% of the variation in spatial patterns of CUE, which was positively correlated with aridity. Our findings are the first large-scale report of the latitudinal patterns of LCV in forests at the species, plant functional group, and community levels and provide new insights into the relationship between LCV and ecosystem functions in forest communities.

Leaf traits may reflect the adaptation mechanisms of plants to the environment. In this study, we investigated leaf morphological and anatomical traits in nine cold-temperate to tropical forests along a 4,200-km transect to test how they vary across latitudinal gradients. The results showed that leaf dry weight decreased (P P P P P P

This paper introduces the two-dimensional (2D) wavelet analysis as a general interrogative technique for the detection of spatial structure in lattice data. The 2D wavelet analysis detects components of hierarchical structure and displays the locational information of the components. Patches and gaps of different spatial scales in graphical presentation of wavelet coefficients can be linked to the local ecological processes that determine patterns at stand or landscape scales. Derived from the 2D wavelet transform function, the calculation of wavelet variance can reduce the four-dimensional data of wavelet coefficients to a two-dimensional wavelet variance function and quantify the contribution of the given scale to the overall pattern. We illustrate the use of the 2D wavelet analysis by analyzing two simulated patterns and identifying the regeneration pattern of the Quercus liaotungensis in a warm temperate forest in north China. Our results indicate that the recruitment of Q. liaotungensis occurs in an overlapping area between the patch of adult and canopy gap at scales of 45 m×45 m–70 m×70 m and 20 m×20 m–30 m×30 m. The regeneration pattern of Q. liaotungensis can be mainly ascribed to a trade-off between two ecological processes: recruitment around parent trees and the physiological light requirements of seedlings and saplings. Our results provide a general portrayal of the regeneration pattern for the dispersal-limited and shade-intolerant Quercus species. We find that the two-dimensional wavelet analysis efficiently characterizes the scale-specific pattern of Q. liaotungensis at different life-history stages.