Spatiotemporal Single-Photon Airy Bullets.

Uninhibited control of the complex spatiotemporal quantum wave function of a single photon has so far remained elusive even though it can dramatically increase the encoding flexibility and thus the information capacity of a photonic quantum link. By fusing temporal waveform generation in an atomic ensemble and spatial single-photon shaping, we hereby demonstrate for the first time complete spatiotemporal control of a propagation invariant (2+1)D Airy single-photon optical bullet. These correlated photons are not only self-accelerating and impervious to spreading as their classical counterparts, but can be concealed and revealed in the presence of strong classical stray light.

First report of Lasiodiplodia pseudotheobromae causing soft rot of plum in China.

Plum (Prunus salicina) is one of the most important fruit tree species worldwide (Valderrama-Soto et al. 2021). In June 2023, the postharvest soft rot symptoms were observed on plum fruits in several fruit markets of Guiyang city, Guizhou province, China. The disease incidence in these markets ranged from 20 to 25% with 70% disease severity. Plum fruits showed rotting, which was characterized by water soaked fruit tissue, softening and presence of whitish mycelia four days post inoculation. In severe conditions, whole fruits become rotted and were covered with white fungal mycelia. Small sections (5 × 3 mm) from 6 diseased plum fruits were surface sterilized by using 75% ethanol for 30 s followed by 0.1% mercuric chloride solution for 5 min, rinsed three times with ddH2O, and then transferred onto potato dextrose agar (PDA) and incubated at 25 ± 2°C for three days. Three pure cultures (GUCC23-0001 to GUCC23-0003) were obtained by transferring a single hyphal tip to new PDA plates. Colonies of these isolates were grayish-white initially, gradually turning to whitish brown with fluffy aerial mycelia and uneven edges and finally turned to a dark gray colony after five days of inoculation. The pseudoparaphyses were hyaline, cylindrical, aseptate, and rounded at apex. Conidia were ellipsoidal, hyaline, unicellular, and 24.2 to 28.6 × 12.3 to 15.5 µm in size (n = 30) (Fig. S1), which were similar to the morphology of Lasiodiplodia pseudotheobromae (Alves et al. 2008). Furthermore, fungal DNA was extracted from fresh mycelia of PDA after seven days by using fungus genomic DNA extraction kit (Biomiga, USA). Partial DNA sequences from four loci including internal transcribed spacer (ITS), translation elongation factor 1-alpha (tef1), beta-tubulin (tub2), and polymerase II second largest subunit (rpb2) were amplified with ITS1 and ITS4 (White et al. 1990), EF1-688F and EF1-1251R (Alves et al. 2008), Bt2a and Bt2b (Glass and Donaldson 1995), and RPB2-LasF and RPB2-LasR, respectively (Cruywagen et al. 2017). GenBank accession numbers are OR361680, OR361681, OR361682 for ITS, OR423394, OR423395, OR423396 for tef1, OR423397, OR423398, OR423399 for tub2, and OR423391, OR423392, OR423393 for rpb2, and gene sequencing showed 99.6 to 100% identity with ex-type strain of L. pseudotheobromae (CBS 116459). Phylogenetic analysis also placed our isolates in a highly supported clade with the reference isolate of L. pseudotheobromae (Fig. S2). Another experiment was designed to confirm the pathogenicity test for additional confirmation. Five mm mycelial plugs of L. pseudotheobromae from a three day old culture on PDA were placed on five surface-sterilized and non-wounded plum fruits for 12 hours and incubated at 25°C ± 2°C for four days. Sterilized fungus free PDA plugs were used as a negative control. Mycelial plugs were removed after 12 hours following which whole fruits were incubated in plastic boxes at 25°C ± 2°C. The experiment was repeated twice. The pathogenicity was evaluated under control conditions in laboratory (relative humidity, 70 ± 5% and temperature 25 ± 5˚C). Plum fruits showed rotting, which was characterized by water soaked fruit tissue, softening and presence of whitish mycelia four days post inoculation. These symptoms and signs were similar to the initially observed symptoms on plums in the markets. No disease symptoms were observed on the control fruits. The re-isolated fungus obtained from inoculated plum fruits was very similar to those isolated from diseased samples in morphology, fulfilling Koch's postulates. To the best of our knowledge, this is the first report of L. pseudotheobromae causing postharvest fruit rot of plum in China. In 2022, the total planting area of plum was 1946.5 thousand hectares, which produces approximately 6626300 tons of plum (Food and Agriculture Organization of the United Nations, 2022). Based on the disease incidence and severity reported in the current study, soft rot of plum may be responsible for nearly 35% of yield losses under severe. Therefore, our study laid a theoretical foundation for the prevention and control of this post-harvest disease of plum.

Exploring the moderating roles of dispositional mindfulness and body image flexibility in the association between body dissatisfaction and disordered eating in Chinese adolescents.

OBJECTIVES: Previous research suggests potential moderating roles of dispositional mindfulness and body image flexibility in the association between body dissatisfaction and disordered eating. However, relevant research is mainly conducted on adult women from Western countries, and limited evidence exists for adolescent samples, especially from non-Western contexts (e.g., China). Thus, this study aimed to examine the moderating roles of dispositional mindfulness and body image flexibility in the relationship between body dissatisfaction and disordered eating in Chinese adolescents. METHOD: We recruited 545 Chinese adolescents (53.9% boys, aged 12-16 years) who completed measures of body dissatisfaction, dispositional mindfulness, body image flexibility, and disordered eating. Moderation analyses were examined with PROCESS macro on SPSS. RESULTS: In separate models, both higher dispositional mindfulness and body image flexibility weakened relationships between body dissatisfaction and disordered eating. However, when both dispositional mindfulness and body image flexibility were entered into the same moderation model, only body image flexibility showed a significant moderating effect. DISCUSSION: Both dispositional mindfulness and body image flexibility may weaken the association between body dissatisfaction and disordered eating in adolescents. However, body image flexibility might have a stronger effect than dispositional mindfulness. These findings suggest that interventions aimed at reducing body dissatisfaction to prevent disordered eating in adolescents may pay more attention to adolescents' body image flexibility.

Quantum Interference between Photons and Single Quanta of Stored Atomic Coherence.

Essential for building quantum networks over remote independent nodes, the indistinguishability of photons has been extensively studied by observing the coincidence dip in the Hong-Ou-Mandel interferometer. However, indistinguishability is not limited to the same type of bosons. For the first time, we hereby observe quantum interference between flying photons and a single quantum of stored atomic coherence (magnon) in an atom-light beam splitter interface. We demonstrate that the Hermiticity of this interface determines the type of quantum interference between photons and magnons. Consequently, not only the bunching behavior that characterizes bosons is observed, but counterintuitively, fermionlike antibunching as well. The hybrid nature of the demonstrated magnon-photon quantum interface can be applied to versatile quantum memory platforms, and can lead to fundamentally different photon distributions from those occurring in boson sampling.

Differential effects of altered precipitation regimes on soil carbon cycles in arid versus humid terrestrial ecosystems.

Changes in precipitation regimes have significant effects on soil carbon (C) cycles; however, these effects may vary in arid versus humid areas. Additionally, the corresponding details of soil C cycles in response to altered precipitation regimes have not been well documented. Here, a meta-analysis was performed using 845 pairwise observations (control vs. increased or decreased precipitation) from 214 published articles to quantify the responses of the input process of exogenous C, the contents of various forms of C in soil, and the soil-atmosphere C fluxes relative to increased or decreased precipitation. The results showed that the effects of altered precipitation regimes did not differ between rainfall and snowfall. Increased precipitation significantly enhanced the soil C inputs, pools and outputs by 18.17%, 18.50%, and 21.04%, respectively, while decreased precipitation led to a significant decline in these soil C parameters by 10.18%, 9.96%, and 17.98%, respectively. The effects of increased precipitation on soil C cycles were more significant in arid areas (where mean annual precipitation, MAP <500 mm), but the effects of decreased precipitation were more significant in humid areas (where MAP ≥500 mm), indicating that the original MAP partially determined the responses of the soil C cycles to altered precipitation regimes. This study implies that for the same of precipitation variation, soil C cycles respond at different magnitudes: not only should the direction (decrease vs. increase) be counted but also the region (arid vs. humid) should be considered. These results deepened our understanding on regional differentiation in soil C cycles under climate change scenarios.

New Intrinsic Ecological Mechanisms of Leaf Nutrient Resorption in Temperate Deciduous Trees.

Leaf nutrient resorption is a critical process in plant nutrient conservation during leaf senescence. However, the ecological mechanisms underlying the large variability in nitrogen (NRE) and phosphorous (PRE) resorption efficiencies among trees remain poorly understood. We conducted a comprehensive study on NRE and PRE variability using 61 tree individuals of 10 temperate broad-leaved tree species. Three potentially interrelated intrinsic ecological mechanisms (i.e., leaf senescence phenology, leaf pigments, and energy residual) were verified. We found that a delayed leaf senescence date, increased degradation of chlorophylls and carotenoids, biosynthesis of anthocyanins, and reduced nonstructural carbohydrates were all positively correlated with NRE and PRE at the individual tree level. The intrinsic factors affecting resorption efficiency were ranked in decreasing order of importance: leaf pigments > energy residual > senescence phenology. These factors explained more variability in NRE than in PRE. Our findings highlight the significance of these three ecological mechanisms in leaf nutrient resorption and have important implications for understanding how nutrient resorption responds to climate change.

Applicability of the generalized wind profile model over mountainous forests.

The analytical equation based on Monin-Obukhov (M-O) similarity theory (i.e., wind profile equation) has been adopted since 1970s for using in the prediction of wind vertical profile over flat terrains, which is mature and accurate. However, its applicability over complex terrains remains unknown. This applicability signifies the accuracy of the estimations of aerodynamic parameters for the boundary layer of non-flat terrain, such as zero-displacement height (d) and aerodynamic roughness length (z0), which will determine the accuracy of frequency correction and source area analysis in calculating carbon, water, and trace gas fluxes based on vorticity covariance method. Therefore, the validation of wind profile model in non-flat terrain is the first step to test whether the flux model needs improvement. We measured three-dimensional wind speed data by using the Ker Towers (three towers in a watershed) at Qingyuan Forest CERN in the Mountainous Region of east Liaoning Province, and compared them with data from Panjin Agricultural Station in the Liaohe Plain, to evaluate the applicability of a generalized wind profile model based on the Monin-Obukhov similarity theory on non-flat terrain. The results showed that the generalized wind profile model could not predict wind speeds accurately of three flux towers separately located in different sites, indicating that wind profile model was not suitable for predicting wind speeds in complex terrains. In the leaf-off and leaf-on periods, the coefficient of determination (R2) between observed and predicted wind speeds ranged from 0.12 to 0.30. Compared to measured values, the standard error of the predicted wind speeds was high up to 2 m·s-1. The predicted wind speeds were high as twice as field-measured wind speed, indicating substantial overestimation. Nevertheless, this model correctly predicted wind speeds in flat agricultural landscape in Panjin Agricultural Station. The R2 between observed wind speeds and predicted wind speed ranged from 0.90 to 0.93. The standard error between observed and predicted values was only 0.5 m·s-1. Results of the F-test showed that the root-mean-square error of the observed and predicted wind speeds in each secondary forest complex terrain was much greater than that in flat agricultural landscape. Terrain was the primary factor affecting the applicability of wind profile model, followed by seasonality (leaf or leafless canopy). The wind profile model was not applicable to the boundary-layer flows over forest canopies in complex terrains, because the d was underestimated or both the d and z0 were underestimated, resulting in inaccurate estimation of aerodynamic height.

[Temporal variation and influencing factors of albedo in a deciduous broad-leaved forest]. / è½å¶é˜”å¶æž—åç §çŽ‡çš„æ—¶é—´å˜åŒ–ä¸Žå½±å“å› ç´ .

In situ measurement of albedo is important for estimating ecosystem energy budget and its remote sensing application. However, the measurement method of albedo on sloping land is limited and the difference in temporal variation in albedo between visible and near-infrared bands remains unclear. Taking a deciduous broad-leaved forest at the Maoershan Forest Ecological Station in Northeast China as an example, we explored the temporal variation and influencing factors of albedo for three bands: incident and reflected solar radiation (SR, 300-2800 nm), photosynthetically active radiation (PAR, 400-700 nm), and near infrared radiation (NIR, 700-2800 nm). The temporal difference in albedo measurements between the two installation methods of radiometers was analyzed. The results showed that, in sunny days, the diurnal variation in SR and NIR albedo had an asymmetric U-shaped curve around the local noon, while PAR increased from sunrise to sunset. In cloudy days, the albedo decreased sharply and then tended to be stable. The measurement with parallel sensors to the slope increased the daily mean value of albedo, but reduced the daily asymmetry of SR and NIR. For the whole growing season, the maximum albedos of SR, NIR and PAR in horizontal measurement were 0.16, 0.27 and 0.11, respectively, and the minimums were 0.07, 0.11 and 0.03, respectively. Albedo in the SR and NIR wavebands increased first and then decreased (the peak value was in July), while PAR showed a contrasting pattern. SR albedo was mainly controlled by NIR rather than PAR. The contribution of the influencing factors was ranked in the order of normalized difference vegetation index (61.7%-78.5%, representing leaf area index) > solar altitude angle (15.4%-36.9%) > clearness index (0.4%-36.9%).

New insights into a microvascular invasion prediction model in hepatocellular carcinoma: A retrospective study from the SEER database and China.

Background and Aims: The prognosis of liver cancer is strongly influenced by microvascular infiltration (MVI). Accurate preoperative MVI prediction can aid clinicians in the selection of suitable treatment options. In this study, we constructed a novel, reliable, and adaptable nomogram for predicting MVI. Methods: Using the Surveillance, Epidemiology, and End Results (SEER) database, we extracted the clinical data of 1,063 patients diagnosed with hepatocellular carcinoma (HCC) and divided it into either a training (n = 739) or an internal validation cohort (n = 326). Based on multivariate analysis, the training cohort data were analyzed and a nomogram was generated for MVI prediction. This was further verified using an internal validation cohort and an external validation cohort involving 293 Chinese patients. Furthermore, to evaluate the efficacy, accuracy, and clinical use of the nomogram, we used concordance index (C-index), calibration curve, and decision curve analysis (DCA) techniques. Results: In accordance with the multivariate analysis, tumor size, tumor number, alpha-fetoprotein (AFP), and histological grade were independently associated with MVI. The established model exhibited satisfactory performance in predicting MVI. The C-indices were 0.719, 0.704, and 0.718 in the training, internal validation, and external validation cohorts, respectively. The calibration curves showed an excellent consistency between the predictions and actual observations. Finally, DCA demonstrated that the newly developed nomogram had favorable clinical utility. Conclusions: We established and verified a novel preoperative MVI prediction model in HCC patients. This model can be a beneficial tool for clinicians in selecting an optimal treatment plan for HCC patients.

[Fine root biomass, production, and turnover rate in a temperate deciduous broadleaved forest in the Maoer Mountain, China]. / å¸½å„¿å±±æ¸©å¸¦è½å¶é˜”å¶æž—ç»†æ ¹ç”Ÿç‰©é‡ã€ç”Ÿäº§åŠ›å’Œå‘¨è½¬çŽ‡.

Fine roots play an important role in energy flow and substance cycling in forests. How-ever, the estimates of biomass, production and turnover of fine roots remain large uncertainties, and the mechanism underlying local-scale spatial variation in fine roots is still unclear. In a temperate secondary forest in the Maoer Mountain in Northeast China, we investigated the vertical distribution of fine root biomass and necromass at the 0-100 cm profile and the dynamics, production and turnover rate of fine root in 0-20 cm soil layer. The sequential coring (including the Decision Matrix and the Maximum-Minimum formula) and the ingrowth core (3 cm diameter and 5 cm diameter) were compared in estimating production and turnover rate of fine roots. Forest stand variables that might affect fine roots were also explored. The results showed that 76.8% of fine root biomass and 62.9% of necromass concentrated in the 0-20 cm soil layer, and that both decreased exponentially with increa-sing soil depth. The seasonal variation in both fine root biomass and necromass was not significant in 0-20 cm soil layer, which might be related to the negligible snowfall in winter and the extremely high precipitation in summer. There was no significant difference in the results of the estimated fine root production between two diameter ingrowth cores. After log-transformed, fine root production and turnover rate estimated by the Decision Matrix, the Maximum-Minimum formula and ingrowth cores were significantly different among methods. With the increases of soil nutrient concentrations, fine root biomass/fine root necromass ratio significantly increased, fine root necromass significantly decreased, whereas fine root biomass, productivity, and turnover rate were not related to soil nutrient. There was a significant positive correlation between fine root production and aboveground woody biomass increment in the previous-year but not current-year.

Dynamics of fine roots in five Chinese temperate forests.

We used a minirhizotron method to investigate spatial and temporal dynamics of fine roots (diameter < or =2 mm) in five Chinese temperate forests: Mongolian oak forest, aspen-birch forest, hardwood forest, Korean pine plantation and Dahurian larch plantation. Fine root dynamics were significantly influenced by forest type, soil layer, and sampling time. The grand mean values varied from 1.99 to 3.21 mm cm(-2) (root length per minirhizotron viewing area) for the fine root standing crop; from 6.7 to 11.6 microm cm(-2) day(-1) for the production; and from 3.2 to 6.1 microm cm(-2) day(-1) for the mortality. All forests had a similar seasonal "sinusoidal" pattern of standing crop, and a "unimodal" pattern of production. However, the seasonal dynamics of the mortality were largely unsynchronized with those of the production. The minimum values of standing crop, production and mortality occurred in March for all forests, whereas the maximum values and occurrence time differed among forest types. The standing crop, production and mortality tended to decrease with soil depth. The different spatiotemporal patterns of fine roots among the forests highlight the need for forest-specific measurements and modeling of fine root dynamics and forest carbon allocation.

[Diurnal variation and light response of net ecosystem carbon exchange in a temperate broadleaved deciduous forest at Maoershan, Northeast China]. / å¸½å„¿å±±æ¸©å¸¦è½å¶é˜”å¶æž—å‡€ç”Ÿæ€ç³»ç»Ÿç¢³äº¤æ¢çš„æ—¥å˜åŒ–åŠå ‰å“åº”ç‰¹å¾.

Photosynthetically active radiation (PAR) is a key environmental factor affecting the change of net ecosystem exchange (NEE) during the daytime. However, the coordinate system of PAR measured by horizontal radiometers over sloping terrain does not match that of NEE after tilt-corrected of the ultrasonic anemometer. Using the temperate deciduous broad-leaved forest at the Maoershan site with an average slope of 9° and a azimuth of 296° as a case, we investigated the diurnal variations in NEE and its driving factors in the growing season (May to September) of 2016. We assessed the differences in estimating light response parameters and the explanations of NEE by other environmental factors between the PAR measured by horizontal and slope-parallel radiometers. The results showed that the diurnal change of NEE in each month of the growing season presented a morning-afternoon asymmetrically unimodal curve: the value was negative (net carbon absorption) about 2.5 h after sunrise, reached the peak around 12:00, then approached zero again at two hours before sunset. The daily net uptake maximized in July and minimized in May. During the whole growing season, the time-lag and difference in the PAR measured by the horizontal versus slope-parallel radiometers led to that the PAR values measured by the horizontal radiometer increased photosynthetic quantum yield (α) and daytime respiration rate (Rd) by 13.3% and 11.5%, respectively, and decreased the maximum photosynthetic efficiency (Amax) by 7.7%. The light response curves of NEE were asymmetrical in the morning and afternoon, with Rd and Amax in the afternoon being greater than that in the morning. Weather conditions affected light response parameters: on cloudy days, Amax was higher than that in sunny days, the α and Rd were lower versus those in sunny days for most conditions. However, the monthly Amax and Rd were generally higher for horizontally measured PAR than for slope-parallelly measured PAR, especially for Amax in the cloudy afternoon. The radiometer-orientation affected the explanation of daytime NEE by air temperature (Ta) and vapor pressure deficit (VPD). The correlation of NEE residual based on the slope-parallel radiometer with Ta and VPD (r ranged: 0.013 to 0.197, 0.098 to 0.224) was tighter than that based on the horizontal radiometer (r ranged: 0.082 to 0.219, 0.162 to 0.282) when the negative correlations with Ta for September was excluded. Our results indicated that the measurements of PAR on the inclined terrains could cause errors in the environmental interpretations of NEE. Such findings had implications for the radiometric measurement of mountain vegetation and the reasonable interpretation of carbon exchange in terrestrial ecosystems.

[Carbon budget estimation based on different methods of CO2 storage flux in forest ecosystems]. / CO2储存通量估算方法对森林生态系统碳收支估测的影响.

Accurate measurement of CO2 storage flux (Fs) in forest ecosystems is of great significance for estimating ecosystem carbon budget by eddy covariance (EC). The errors in the estimation of ecosystem carbon budget caused by different methods for calculating Fs has yet not been comprehensively assessed. Using data from an open-path EC system and an eight-level CO2/H2O profile system (AP100, Campbell Scientific Inc., USA) in a broadleaved deciduous forest at the Maoer-shan in 2018, we evaluated the methodological effect of Fs[2-min mean profile (P2 min), 30-min mean profile (P30 min) and 30-min mean EC single point (Ps)] on the estimation of net ecosystem exchange (NEE), ecosystem respiration (Re), and gross primary productivity (GPP). The results showed that the impact of Fs methods on forest carbon flux generally increased with the increases of time scale, indicating that gap-filling of flux data would further amplify the impacts of Fs estimation methods. At the annual scale, NEE based on P2 min and Ps methods were 36.3% and 29.4% lower than that based on P30 min, while Re based on P2 min was higher than that based on P30 min and Ps by 8.7%. The GPP based on P2 min was 5.4% higher, while that based on Ps was 2.1% lower than that based on P30 min. The traditional P30 min ignored the instantaneous changes in CO2 concentration, Ps missed the changes of CO2 concentration within canopy, and thus both underestimated the actual Re. The approximately instantaneous profile (2-min mean profile) had higher temporal and spatial resolution and could more accurately estimate forest carbon budget with non-flat terrain and complex canopy structure. Our findings had great implications for solving the underestimation of forest Re and GPP as well as the overestimation of net carbon sink on complex conditions with the EC method.

[Functions and applications of Multi-Tower Platform of Qingyuan Forest Ecosystem Research Station of Chinese Academy of Sciences]. / ä¸­å›½ç§‘å­¦é™¢æ¸ åŽŸæ£®æž—ç”Ÿæ€ç³»ç»Ÿè§‚æµ‹ç ”ç©¶ç«™å¡”ç¾¤å¹³å°çš„åŠŸèƒ½å’Œåº”ç”¨.

The relationship between the structure and function of forest ecosystems is the main intere-sts in the research area of forest ecology and management. However, over complex terrains in particular, these studies had been challenged as uneasy tasks due to the limitations in the forest survey and measurement techniques and other supporting technologies. Chinese Academy of Sciences (CAS) funded "Multi-Tower LiDAR/ECFlux Platform for Monitoring the Structure and Function of Secondary Forest Ecosystems" (Multi-Tower Platform, MTP) as a field station network corner-stone research infrastructure project, which was completed by Qingyuan Forest CERN (Chinese Ecosystem Research Network). In a distinctively-bounded and monitored-outlet watershed, the MTP was integrated by light detection and ranging (LiDAR) scanners, eddy covariance (EC) flux instrument systems, whole- and sub-watershed hydrology station network, long-term forest plot arrays, and live data center. Using LiDAR scanning, the MTP can get cloud data for holographic information on canopy structure. The EC-flux instrument system and hydrology station network along with forest plot arrays could ensure the reliability of water and carbon observations over this complex terrain, which allows to verify the studies on flux measurement technologies and methods, as well as to understand the processes of ecohydrology and CO2 exchange between forest ecosystem and the atmosphere. Further, we can also assess the primary ecosystem services, including water conservation and carbon sequestration. All the data from "tower-station" were streamed through wireless network, which would facilitate data monitoring, management, and sharing. There are three tasks of MTP team: 1) defining innovative methods and descriptors to quantify three-dimensional forest structure; 2) developing theories and techniques to measure CO2/H2O fluxes and other trace gases over complex terrains; 3) understanding the relationship between structure and function of forest ecosystems, providing information and rationales for forest management practices to assure broad and sustainable benefits from forests.

Proteolysis of endomorphin-1 by brain synaptic membrane-associated peptidases.

The biotransformation of endomorphin-1 (EM-1) by brain synaptic membranes has been studied. Peptide fragments of EM-1 that were formed during incubation with membrane preparations in vitro were isolated by High-performance liquid chromatography (HPLC) and characterized using determination of amino acid composition. At pH 7.4, two degradation products, EM-1(1-3) and EM-1(1-2), were identified. EM-1 was degraded 77.5% at 30 min incubation with synaptic membranes. The time course of the experiments and the effect of carboxypeptidase inhibitor (CPI) demonstrated that the proteolysis reaction involves the participation of carboxypeptidase activity.

[Error analysis of CO2 storage flux in a temperate deciduous broadleaved forest based on different scalar variables].

Using the measurement data from an 8-level vertical profile of CO2/H2 0 in a temperate deciduous broadleaved forest at the Maoershan Forest Ecosystem Research Station, Northeast China, this paper quantified the errors of CO2 storage flux (Fs ) calculated with three scalar variables, i. e. , CO2 density (rho c), molar fraction (cc), and molar mixing ratio relative to dry air (Xc). The dry air storage in the control volume of flux measurement was not a constant, and thus, the fluctuation of the dry air storage could cause the CO2 molecules transporting out of or into the control volume, i. e. , the variation of the dry air storage adjustment term (Fsd). During nighttime and day-night transition periods, the relative magnitude of Fsd to eddy flux was larger, and ignoring the Fsd could introduce errors in calculating the net CO2 exchange between the forest ecosystem and the atmosphere. Three error sources in the Fs calculation could be introduced from the atmospheric hydrothermal processes, i. e. , 1) air temperature fluctuation, which could cause the largest error, with one order of magnitude larger than that caused by atmospheric pressure (P) , 2) water vapor, its effect being larger than that of P in warm and moist summer but smaller in cold and dry winter, and 3) P, whose effect was generally smaller throughout the year. In estimating the effective CO2 storage (Fs_E) , the Fs value calculated with rho c, cc, and Xc was overestimated averagely by 8. 5%, suggested that in the calculation of Fs, adopting the Xc conservation to atmospheric hydrothermal processes could be more appropriate to minimize the potential errors.

[Spatial variation of non-structural carbohydrates in Betula platyphylla and Tilia amurensis stems].

Taking the two diffuse-porous tree species Betula platyphylla and Tilia amurensis in a temperate forest in Northeast China as test objects, this paper studied the spatial variation of the non-structural carbohydrates (NSC) concentrations in the stem xylem after leaf-fall. For the two tree species, the concentrations of total non-structural carbohydrate (TNC, soluble sugars plus starch) and soluble sugars in the stem xylem decreased gradually with the increasing depth from cambium to pith, whereas the starch concentration showed little radial variation. There was still a substantial amount of NSC in the inner wood close to pith. The concentrations of the NSC in the two species stems decreased gradually from the stump to the breast height, and then increased vertically. The maximum concentrations of the TNC, soluble sugars, and starch occurred at different heights, depending on the species and the TNC components. The ratio of sugar to starch showed a contrasting vertical trend for the two species, i. e., increasing from the stump to the top for B. platyphylla, but decreasing for T. amurensis. The estimation error of the stem NSC storage was mainly from the axial variation, and then, from the radial variation of NSC concentration. The TNC concentration (1.0% dry mass) in the stem of shade-intolerant species B. platyphylla was significantly lower than that (4.3% dry mass) of shade-tolerant species T. amurensis, which could be related to their different life-history strategies. Applying the sampling protocols considering the axial and radial variations of NSC could effectively reduce the potential uncertainty in estimating the NSC storage at tree or stand level.

[Soil nitrous oxide emission in four temperate forests in northeastern China].

Seasonal dynamics of N2O flux and its controlling factors for four representative temperate forests in northeastern China were examined with a static closed chamber-gas chromatograph technique. These forests were Korean pine (Pinus koraiensis) plantation, Dahurian larch (Larix gmelinii) plantation, Mongolian oak ( Quercus mongolica) forest and hardwood broadleaved forest (dominated by Fraxinus mandshurica, Juglans mandshurica, and Phellodendron amurense). The results showed that all ecosystems were overall atmospheric N2O source during the growing season. The N2O flux (microg x m(-2) x h(-1)) decreased in order of the hardwood broadleaved forest (21.0 +/- 4.9) > the pine plantation (17.6 +/- 4. 6) > the larch plantation (9.8 +/- 5.9) > the oak forest (1.6 +/- 12.6). Overall, there was no consistent seasonal pattern in N2O flux for the four ecosystems. The N2O flux was significantly positively correlated to soil gravimetric water content (0-10 cm depth) consistently for all ecosystems, but significantly negatively correlated to NO3(-)-N content for each ecosystem. However, the responses of N2O flux to soil temperature and NH4(+)-N differed among the ecosystems. The N2O fluxes for the coniferous plantations were positively correlated to NH4(+)-N, but not correlated to the soil temperature at 5 cm depth; while those for the broadleaved forests displayed an opposite trend. The soil water content was the dominator of soil N2O emission for the forests in 2007 perhaps resulting from relative drought in the year. Interactions of vegetation type, environmental factor, and nitrogen availability to soil N2O emission should be further studied in the future.