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Snowpack in winter is very sensitive to climate change, and may in turn induce complex effects on terrestrial biochemistry processes. Here we synthesized the results from 49 papers based on snow depth manipulation experiments and conducted a meta-analysis to evaluate the general response of 9 variables related to terrestrial carbon pools and dynamics to the altered snowpack depth. Our meta-analysis results indicated that increasing snowpack depth significantly increased litter biomass (+18.4%), MBC (+18.2%) and CO2 emission (+15.5%), and significantly decreased litter C: N ratio (−5.8%) and total soil carbon (−28.5%) under snow addition manipulation, but did not significantly affect fine root biomass, MBC: MBN ratio and soil dissolved organic carbon (DOC). However, increasing snowpack depth only significantly altered litter C: N ratio (+11.2%) under snow removal manipulation. The different responses between snow addition and removal were possibly related to the higher soil temperature and moisture under snow addition than under snow removal manipulation experiments. In addition, the effect of increasing snowpack depth on CH4 flux was not significant, presumably because all these studies were compiled from snow-removal experiments. These results are useful for a better understanding of the effects of altered snowpack on terrestrial carbon cycling under climate change scenarios.

Improved understanding of the link between photosynthesis and below-ground processes is needed to better understand ecosystem carbon (C) cycling and its feedback to climate change. We conducted a short-term shading and nitrogen (N) addition experiment from June to September 2013 to investigate the effect of photosynthate supply by Manchurian Ash (Fraxinus mandshurica) seedlings on soil respiration (SR). Shading significantly reduced SR in early and middle growing season, but not in late growing season, leading to a decrease in mean SR by 24 % in N-unfertilized treatments. N addition increased mean SR by 42 % in un-shaded treatment. The stimulation of SR was largely attributed to accelerated autotrophic respiration by increasing photosynthesis, leaf area index and belowground biomass. Shading reduced mean SR by 32 % in N addition treatment. The strengthened shading effect on SR resulted from N addition was because of more photosynthates supply at low soil temperature. Our findings highlight the predominance of photosynthates supply in regulating the responses of C cycling to global change.

Bacteria and fungi, representing two major soil microorganism groups, play an important role in global nutrient biogeochemistry. Biogeographic patterns of bacterial and fungal biomass are of fundamental importance for mechanistically understanding nutrient cycling. We synthesized 1323 data points of phospholipid fatty acid-derived fungal biomass C (FBC), bacterial biomass C (BBC), and fungi:bacteria (F:B) ratio in topsoil, spanning 11 major biomes. The FBC, BBC, and F:B ratio display clear biogeographic patterns along latitude and environmental gradients including mean annual temperature, mean annual precipitation, net primary productivity, root C density, soil temperature, soil moisture, and edaphic factors. At the biome level, tundra has the highest FBC and BBC densities at 3684 (95% confidence interval: 1678–8084) mg kg−1 and 428 (237–774) mg kg−1, respectively; desert has the lowest FBC and BBC densities at 16.92 (14.4–19.89) mg kg−1 and 6.83 (6.1–7.65) mg kg−1, respectively. The F:B ratio varies dramatically, ranging from 1.8 (1.6–2.1) in savanna to 8.6 (6.7–11.0) in tundra. An empirical model was developed for the F:B ratio and it is combined with a global dataset of soil microbial biomass C to produce global maps for FBC and BBC in 0–30 cm topsoil. Across the globe, the highest FBC is found in boreal forest and tundra while the highest BBC is in boreal forest and tropical/subtropical forest, the lowest FBC and BBC are in shrub and desert. Global stocks of living microbial biomass C were estimated to be 12.6 (6.6–16.4) Pg C for FBC and 4.3 (0.5–10.3) Pg C for BBC in topsoil. These findings advance our understanding of the global distribution of fungal and bacterial biomass, which facilitates the incorporation of fungi and bacteria into Earth system models. The global maps of bacterial and fungal biomass serve as a benchmark for validating microbial models in simulating the global C cycle under a changing climate.

Carbon (C) isotope discrimination during photosynthetic CO2 assimilation has been extensively studied, but the whole process of fractionation from leaf to soil has been less well investigated. In the present study, we investigated the &delta, 13C signature along the C transfer pathway from air to soil in a coniferous and broad-leaved mixed forest in northeast China and examined the relationship between &delta, 13C of respiratory fluxes (leaf, trunk, soil, and the entire ecosystem) and environmental factors over a full growing season. This study found that the &delta, 13C signal of CO2 from canopy air was strongly imprinted in the organic and respiratory pools throughout C transfer due to the effects of discrimination and isotopic mixing on C assimilation, allocation, and respiration processes. A significant difference in isotopic patterns was found between conifer and broadleaf species in terms of seasonal variations in leaf organic matter. This study also found that &delta, 13C in trunk respiration, compared with that in leaf and soil respiration, was more sensitive to seasonal variations of environmental factors, especially soil temperature and soil moisture. Variation in the &delta, 13C of ecosystem respiration was correlated with air temperature with no time lag and correlated with soil temperature and vapor pressure deficit with a lag time of 10 days, but this correlation was relatively weak, indicating a delayed linkage between above- and belowground processes. The isotopic linkage might be confounded by variations in atmospheric aerodynamic and soil diffusion conditions. These results will help with understanding species differences in isotopic patterns and promoting the incorporation of more influencing factors related to isotopic variation into process-based ecosystem models.

Permafrost play an important role in regulating global climate system. We analyzed the gross primary productivity (GPP), net primary productivity (NPP), and evapotranspiration (ET) derived from MODIS and three earth system models participated in the Coupled Model Inter-comparison Project Phase 6 (CMIP6) in the Asian permafrost region. The water use efficiency (WUE) was further computed. The simulated GPP, NPP, and ET show slightly increasing trends during historical period (1900-2014) and strong increasing trends in projection period (2015-2100), and projected impacts of climate change on all variables are greater under high-emission scenarios than low-emission scenarios. Further analysis revealed higher increases in GPP and NPP than that of ET, indicating that vegetation carbon sequestration governs the growing WUE under historical and projected periods in this region. The GPP, NPP and ET showed higher changing rates in western, central and southeast areas of this region, and WUE (WUEGPP, and WUENPP) shows the similar spatial pattern. Compared to MODIS-derived GPP, NPP, and ET during 2000-2014, Earth system models yield the best estimates for NPP, while slight underestimations for GPP and ET, and thus slight overestimations for WUEGPP and WUENPP. This study highlights the predominant role of vegetation activity in regulating regional WUE in Asian permafrost region under future climate change. Vegetation domination of the growing water use efficiency implies that the permafrost region may continue acting efficiently in sequestrating atmospheric carbon in terms of water consumption throughout the 21st century.

Non-structural carbohydrates (NSC) play a central role in plant functioning as energy carriers and building blocks for primary and secondary metabolism. Many studies have investigated how environmental and anthropogenic changes, like increasingly frequent and severe drought episodes, elevated CO2 and atmospheric nitrogen (N) deposition, influence NSC concentrations in individual trees. However, this wealth of data has not been analyzed yet to identify general trends using a common statistical framework. A thorough understanding of tree responses to global change is required for making realistic predictions of vegetation dynamics. Here we compiled data from 57 experimental studies on 71 tree species and conducted a meta-analysis to evaluate general responses of stored soluble sugars, starch and total NSC (soluble sugars + starch) concentrations in different tree organs (foliage, above-ground wood and roots) to drought, elevated CO2 and N deposition. We found that drought significantly decreased total NSC in roots (-17.3%), but not in foliage and above-ground woody tissues (bole, branch, stem and/or twig). Elevated CO2 significantly increased total NSC in foliage (+26.2%) and roots (+12.8%), but not in above-ground wood. By contrast, total NSC significantly decreased in roots (-17.9%), increased in above-ground wood (+6.1%), but was unaffected in foliage from N fertilization. In addition, the response of NSC to three global change drivers was strongly affected by tree taxonomic type, leaf habit, tree age and treatment intensity. Our results pave the way for a better understanding of general tree function responses to drought, elevated CO2 and N fertilization. The existing data also reveal that more long-term studies on mature trees that allow testing interactions between these factors are urgently needed to provide a basis for forecasting tree responses to environmental change at the global scale.

Water retained on tree leaves after rainfall, dew, or fog impacts transpiration. To determine the impact of leaf retained water (LRW) on the transpiration of trees, the difference between transpiration rates of different species with and without water sprayed on the leaves was measured. Results show that transpiration was inhibited by LRW. Both the inhibition extent and duration of LRW were higher on broadleaf species than on coniferous species. Under conditions of saturated LRW of the tree crown, mean transpiration inhibition rates of the test species were 0.32 (Quercus mongolica Fisch. ex Ledeb.), 0.25 (Acer mono), 0.37 (Tilia amurensis Rupr.), 0.31 (Fraxinus mandshurica Rupr.), 0.22 (Pinus koraiensis Siebold & Zucc.), 0.22 (Abies nephrolepis (Trautv. ex Maxim.) Maxim.), and 0.23 (Picea asperata Mast.). Mean inhibition rate and inhibition time for broadleaf species were 0.31 and 115 min, which were 40% higher and 27 min longer than those for coniferous species, respectively. The transpiration inhibition rate of LRW increased linearly with the LRW amount, and there was a higher transpiration inhibition rate in broadleaf species than in coniferous species for the same amount of LRW. Mean rising velocity of the inhibition with LRW amount for broadleaf species was 0.53%, whereas it was only 0.15% for the coniferous species.

Global atmospheric nitrogen deposition has increased steadily since the 20th century, and has complex effects on terrestrial ecosystems. This work synthesized results from 54 papers and conducted a meta-analysis to evaluate the general response of 15 variables related to plant root traits to simulated nitrogen deposition. Simulated nitrogen deposition resulted in significantly decreasing fine root biomass (

Land use changes are often considered to be the main factors influencing soil infiltration. But the difference of soil infiltration capacity for different land use type is less clear. In this paper, we conduct a meta-analysis of all 42 papers that could be found associated with the effects of land use changes on soil infiltration capacity. The results showed that soil initial and steady infiltration rates increased after land use changes from grassland to forest (+41.35%, /), shrubland to forest (+42.73%, /) and cropland to agroforestry (+70.28%, +84.17%). Soil infiltration rates declined after land use changes from grassland to cropland (/, -45.23%), shrubland to cropland (-64.24%, /) and forest to cropland (-53.58%, -42.15%). It was evident that soil infiltration rates were negatively related to soil bulk density and initial moisture and positively related to soil total porosity and organic matter content. In sum, establishing agroforestry ecosystem was beneficial to improve soil infiltration capacity compare to cropland and plantation, which has important implications for developing sustainable agriculture and forest from the viewpoint of soil and water conservation.

Understanding the carbon dynamics in grassland is essential to precisely estimate global atmospheric carbon budget in response to climatic change. Eddy flux measurements were carried out during 2011 and 2012 to characterize seasonal and annual variability of carbon exchanges above a temperate meadow in eastern Inner Mongolia, China. The CO2 flux showed obvious diurnal variations and the monthly mean amplitudes of diurnal course followed June/July > August > May > September. The daily maximum NEE reached up to −8.0 and −7.7 g C m−2 for 2011 and 2012, respectively. CO2 uptake was mainly from May to August, with seasonal peaks of −16.0 g C m−2 day−1 in both two years. Gross primary production (GPP) and ecosystem respiration (Re) were −1,084.5, 987.1 g C m−2 year−1 in 2011, and −1,123.3, 1,040.2 g C m−2 year−1 in 2012, respectively. The meadow acted as a stable carbon sink, with integrated net ecosystem exchange (NEE) of −97.4 and −83.1 g C m−2 year−1 for 2011 and 2012, respectively. Compared with 2011, the ecosystem assimilated more carbon and meanwhile respired even more, leading to a less carbon sequestration in 2012. PAR and leaf area index (LAI) dominated the seasonal variations in NEE, with PAR explaining 61–69 % of the variance in NEE as LAI maintaining the plateau during June to July. Harvest significantly decreased ecosystem carbon uptake. The interannual variability in GPP and Re resulted primarily from the variations in temperature and its effect on biomass growth.

The diversity and community structure of arthropods in an organic double-cropped rice ecosystem in Guangdong Province, China was studied. We compared the arthropod communities in the early season (Apr–Jul) crop to those in the late season (Aug–Nov) crop in 2009. The comparisons were undertaken using a combination of community assessment approaches, including morphospecies richness, the Shannon-Weaver diversity index, H', the Pielou-evenness index, J, the Simpson dominance index C, the Jaccard similarity index q and the compositions of the sub communities. We collected 114 species of arthropods, which consisted of including 58 species of spiders, 16 species of predatory insects, 25 species of phytophagous insects, 15 species of neutral/other insects, in early season crop. Subsequently we collected 109 species of arthropods, which consisted of 50 species of spiders, 19 species of predatory insects, 24 species of phytophagous insects, and 16 species of neutral/other insects, in the late season crop....

Dongxiang wild rice, Oryza rufipogon Griff. (Poales: Poaceae), has many excellent traits that are of interest to botanists and plant breeders. However, arthropod biodiversity and community structure for this rare species are not well known. Therefore, we investigated the arthropod communities in natural plots of Dongxiang wild rice at three locations in Jiangxi Province, China. The diversity and dominance indices of the arthropod communities within wild rice plots fluctuated only slightly over time. However, the diversity and dominance indices differed significantly among actively growing plots. The vegetation complex surrounding the wild rice plots affected the similarity coefficients of the arthropod communities within them. The surrounding vegetation also significantly affected the diversity and dominance indices of arthropod functional groups, except for the parasitoid group. The dominance of phytophagous groups, such as planthoppers, also was suppressed in more diverse arthropod communities...

Laboratory assays were conducted to assess the potential of pymetrozine, a novel azomethine pyridine insecticide, against the brown planthopper, Nilaparvata lugens (Stal) (Homoptera: Delphacidae). All nymphal instars were treated with the pymetrozine concentrations of 400, 200, 100, 50, 25 mg/l, and then maintained in incubators at 26 ± 1°C on a photoperiod of 16:8 h (L: D). At 24, 48, 72, and 120 h after treatment, mortality was recorded. Greater numbers of nymphs were killed at a faster rate with the higher concentrations (mortality of 70.7% with 400 mg/l and 63.8% with 200 mg/l at 24 h, first -second) than at the median concentrations (mortality of 51.7% with 100 mg/l and 50% with 50 mg/l at 24 h, first -second) and the lower concentration (mortality of 25.9% with 25 mg/l at 24 h, first -second), whereas mortality in the control remained low (3.3% with distilled water at 24 h, first -second). The first and second instars were the most susceptible with median lethal concentrations [LC50] of 76....

Soil respiration is the largest terrestrial carbon flux into the atmosphere, and different tree species could directly influence root derived respiration and indirectly regulate soil respiration rates by altering soil chemical and microbial properties. In this study, we assessed the small scale spatial heterogeneity of soil respiration and the microbial community below the canopy of three dominant tree species (Korean pine (Pinus koraiensis), Mongolian oak (Quercus mongolica), and Manchuria ash (Fraxinus mandshurica)) in a temperate mixed forest in Northeast China. Soil respiration differed significantly during several months and increased in the order of oak

To develop an empirical model for ground snow sublimation beneath canopy, a weighing measurement experiment was conducted using snow samples with different density in the broadleaved Koreanpine mixed forest in Changbai Mountains, Northeastern China. Eddy covariance measurement for water vapor flux was used to evaluate the model performance. Eddy covariance data showed that the daytime sublimation was much larger than the nighttime sublimation, and 94.3% of daily sublimation occurred within the 8 h from 8:00 to 16:00. Daytime sublimation showed a linear relationship with snow density, and the regression coefficients between them varied with meteorological variables. The regression slope was closely correlated to solar radiation (R2=0.92) and water vapor pressure (R2=0.79), whereas the regression intercept was closely correlated to air temperature (R2=0.92). Based on the regression relationships among sublimation, snow density, and meteorological variables, a nonlinear empirical sublimation model wi...

Frost heave, which is the volumetric expansion of frozen soil, has great ecological significance, since it creates water storage spaces in soils at the beginning of the growing season in cold temperate forests. To understand the characteristics of frost heave in seasonally frozen soil and the factors that impact its extent, we investigated the frost heave rates of forest soil from different depths and with different soil moisture contents, using both lab-based simulation and in situ measurementin a broadleaved Korean pine forest in the Changbai Mountains (northeastern China). We found that frost heave was mainly affected by soil moisture content, soil type, and gravitational pressure. Frost heave rate increased linearly with soil moisture content, andfor each 100% increase in soil moisture content, the frost heave rate increased by 41.6% (loam, upper layer), 17.2% (albic soil, middle layer), and 4.6% (loess, lower layer). Under the same soil moisture content,the frost heave rate of loam was highest, whereas that of loess was lowest, and the frost heave of the uppermost 15 cm, which is the biologicallyenrichedlayer, accounted for ~55% of the frost heave. As a result, we determined the empirical relationship between frost heave and freezing depth, which is important for interpreting the effects of frost heave on increases in the storage space of forest soils and for calculating changes in soil porosity.

Ecosystem evapotranspiration links surface energy and water balance, which is very important to the forming and evolution of regional climate. To understand the evapotranspiration dynamic over the temperate meadow in Inner Mongolia grassland, a long-term continuous measurement of water vapour flux was conducted using eddy covariance technique from 2008 to 2013. The results showed that the seasonal variation of daily evapotranspiration displayed a unimodal pattern with maximum value of 6.45 mm day−1. The mean value of annual evapotranspiration (ET) was 650 mm with 72 % occurring during the growing season from May to September. The annual evapotranspiration was larger than the annual precipitation (P), while less than the annual evaporation (E). The ET/P reached up to 1.91, while the ET/E was only 0.60. The evapotranspiration was not limited by precipitation due to additional water supply from surrounding dunes. The daily evapotranspiration was mainly driven by atmospheric moisture demand in the growing season with high Priestley–Taylor parameter, averaged 1.04. The daily evapotranspiration presented positive correlation with net radiation, and the correlation was affected by water vapour pressure deficit. The net radiation and water vapour pressure deficit controlled the evapotranspiration process together. The study site had the largest annual evapotranspiration and ET/P compared with the other ecosystems along the transection of Northeast China Transect, International Geosphere Biosphere Programme. The harvest activity could increase the albedo and then decrease the available energy of the surface, eventually reducing the monthly evapotranspiration as much as 33.98 % in September.

Hydrological processes change from the impacts of climate variability and human activities. Runoff in the upper reaches of the Hun-Taizi River basin, which is mainly covered by forests in northeast China, decreased from 1960 to 2006. The data used in this study were based on runoff records from six hydrological stations in the upper reaches of the Hun-Taizi River basin. Nonparametric Mann–Kendall statistic was used to identify change trends and abrupt change points and consequently analyze the change characteristics in hydrological processes. The abrupt change in the annual runoff in most subcatchments appeared after 1975. Finally, the effects of climate change and land cover change on water resources were identified using regression analysis and a hydrology model. Results of the regression analysis suggest that the correlation coefficients between precipitation and runoff prior to the abrupt change were higher compared with those after the abrupt change. Moreover, using hydrology model analysis, the water yield was found to increase because of the decrease in forest land. Copyright © 2012 John Wiley & Sons, Ltd.

Laboratory assays explored the potential of paichongding, a novel neonicotinoid insecticide, against the brown planthopper, Nilaparvata lugens(Stal) (Homoptera: Delphacidae). Cumulative mortality of N. lugensfollowing exposure was concentration and time dependent. Nilaparvata lugensnymphs were more sensitive to paichongding compared with the adults, and the first and second instars were the most susceptible. Median lethal concentration (LC50) values to instars I–II at 24, 48, and 72 h after treatment were 7.00, 0.46, and 0.13 mg/L, respectively. Brachypterous adults were more susceptible than macropterous adults, and the macropterous females were the least susceptible with LC50 values at 24, 48, and 72 h after treatment of 97.05, 58.70, and 1.26 mg/L, respectively. The median lethal time (LT50) significantly decreased with increasing concentration of paichongding. The LT50 for instars I–II decreased from 62.38 h at 0.2 mg/L to 25.13 h at 3.2 mg/L, whereas the LT50 values for macropterous females ...

On the basis of eddy covariance measurements, the results of three years (2005–2007) of direct evapotranspiration (ET) measurements over a mixed temperate forest in Northeast China are presented. The diurnal and seasonal variations in ET and its main driving factors were analyzed. Annual ET values for the forest were 437, 506, and 632 mm in 2005, 2006, and 2007, respectively. The contribution of ET during the dormant season was not negligible, ranging from 17 to 23% of the annual ET for the study years. On an annual course, the increase in ET is associated with the increasing air temperature (Ta) and plant growth in late April and early May, peaking in July or August with monthly mean rates of 2.9 mm day−1 (July 2005), 3.4 mm day−1 (July 2006), and 3.8 mm day−1 (August 2007). Priestley-Taylor parameter α also varied seasonally, with its minimum and maximum values occurring in the dormant and growth seasons, respectively. During the growth season, the values of α were generally between 0.6 and 0...

Summary Hydrological processes in river systems have been changing under the impacts of both climate variability and human activities. The non-parametric Mann–Kendall statistic was used to identify change trends and points in the annual streamflow in the Hun–Tai River basin in northeast China. The identifications were based on streamflow records from six hydrological stations during 1961–2006, and the purpose was to analyze the change characteristics of the hydrological processes. The results indicated that all hydrological stations presented downward trends in annual streamflows. Abrupt changes in the annual streamflow occurred around 1978 in the Hun River basin, and around 1998 in the Taizi River basin. The impact of climate variability on the mean annual streamflow was also analyzed based on the relationships among streamflow, precipitation, and potential evapotranspiration. Precipitation and meteorological data from 22 rainfall stations and 10 weather stations within the basin were employed in the analysis. Daily potential evapotranspiration was calculated using the Penman–Monteith equation. Climate variability was estimated to account for 43% of the reduction in the annual streamflow, and human activities accounted for about 57%.

Summary Based on the eddy flux and meteorological measurements, we analyzed variation of the components of energy balance before, during and after the snow coverage in dormant season over temperate meadow. The results showed that the energy balance ratio EBR was 0.76, lowest in the fresh snow phase and positively correlated with friction velocity u∗. Furthermore, the energy balance closure error had a diurnal cycle. The radiation partition and energy balance changed in the presence of the snow cover. The surface albedo was high during snow coverage (maximum in the fresh snow phase) and low in the snow-free period (including pre-snow and snow-melted phases). The ratio of net radiation Rn to solar radiation Q was higher in the snow-melted phase, and lower in the fresh snow phase, so did the peaks in diurnal courses of the energy fluxes (Rn, latent heat flux LE, sensible heat flux H, and soil and storage heat flux G + S). The daily-integrated value of H increased followed by Rn in the snow-melting phase, LE and G + S increased quickly followed by Rn in the snow-melted phase. Daily average Bowen ratio β was large in the snow-melting phase and low in the snow-melted phase, indicating that more energy partitioning of Rn into H in the snow-melting phase but LE in the snow-melted phase.

Bioassay of nitenpyram was conducted on the planthopper Nilaparvata lugens (Stål) (Hemiptera: Delphacidae) in the laboratory by using the rice-stem dipping method. The resulting data were analyzed using the complementary log-log time-concentration-mortality modeling technique, yielding the parameters for time and concentration effects of nitenpyram against N. lugens instars. The LC50 values to instars I and II estimated for 24, 48, and 72 h after treatment were 1.03, 0.27, and 0.11 mg/liter, respectively. These values were lower than those for instars III and IV and instars V at the same times. The estimates of LT50 for instars I and II were decreased from 69.06 to 16.22 h with the increasing concentration from 0.125 to 2 mg/liter; the same estimates for both instars III and IV and instars V at the concentrations of 1-2 mg/liter were close to each other, ranging from 33.11 to 44.16 h, much higher than the values of instars I and II at the same concentration. Based on the time-concentration-mortality relationships fitted and the virulence indices (LC50 and LT50) estimated, nitenpyram is a promising pesticide for N. lugens control.

The Nilaparvata lugens (Stal) is a major rice pest in Asia. Nitenpyram is a novel neonicotinoid insecticide developed by Takeda Chemical Industry Co., Ltd. The effects of sublethal concentration (LC30) of this insecticide on life-table parameters and wing formation of N. lugens were studied in the laboratory. The results showed that nitenpyram could reduce the fecundity of N. lugens to a great extent and demonstrated further activity against this pest in addition to direct toxicity. The fecundity (eggs per female) of N. lugens treated with a sublethal concentration of nitenpyram was 75.4% of the control in macropterous cohorts, and 69.8% in brachypterous cohorts. A sublethal concentration of nitenpyram showed the significant induction of macropterous adults in both macropterous and brachypterous cohorts, which are important in the control of N. lugens, particularly in the prediction of emigrating populations in newly colonized areas.

This review describes the effects of ultraviolet-B (UV-B) radiation on plant growth and development, photosynthesis and photosynthetic pigments and UV-B absorbing compounds. Moreover, plant ecosystem level responses to elevated UV-B radiation and interactions of UV-B radiation with abiotic and biotic factors were also involved. Results collected in this review suggest that approximately two-thirds terrestrial plant species are significantly affected by increase in UV-B radiation. The majority of evidences indicate that elevated UV-B radiation is usually detrimental but there exists tremendous variability in the sensitivity of species to UV-B radiation, and sensitivity also differs among cultivars of the same species.

Dune-interdune is the main landscape pattern of desert areas, such as the Horqin sandy land of Northeastern China. Exploring the temporal and spatial variation of the water balance is crucial for efficient vegetation restoration at the micro-landform scale. The SWMS-2D model was used to estimate the seasonal variations of the water balance including evapotranspiration, soil water storage changes, lateral flow and drainage, and to examine the effects of micro-landforms (i.e., the top, upper, down, and bottom positions of the dune slope, and the interdune lowland area) on these components from May to October 2013 and 2015. Results showed that the soil water content was sensitive to rainfall pulses, particularly large precipitation events. Over 70% of the total evapotranspiration occurred from June to August, with a maximum daily value of 6.56 mm. At a monthly scale, evapotranspiration was not synchronous with precipitation. The ratio of evapotranspiration to precipitation was 1.84, 0.39, 2.49, 0.93, 2.26, and 1.14 in May, June, July, August, September, and October 2013 (a wet year), respectively; and 2.40, 1.11, 0.69, 2.14, 1.07, and 1.11 in 2015 (a dry year), respectively. The components of the water balance were significantly different among different micro-landforms. Evapotranspiration of a lowland area was greater than that in other micro-landforms, and the value in the wet year (2013) was significantly greater than that in the dry year (2015). However, water consumption in the lowland area was similar in both years. At the top, upper, down, and bottom positions of the dune slope, the ratio of evapotranspiration to precipitation in the wet year (2013) was 96%, 97%, 86%, and 96%, respectively; while in the dry year (2015), the ratio was 103%, 103%, 88%, and 104%. Therefore, in the dry year, evapotranspiration was generally larger than precipitation, indicating that almost all water from precipitation was evaporated. The lateral flow of the root zone from top to bottom accounted for only a small portion of water budget at the growing season scale. The results could be generalized to other similar region with corresponding model calibration, and would help to reveal seasonal variations of water balance components under the local topography, climate, soil, and vegetation conditions.

Based on the hydrological data from the Beikouqian and Nandianyu stations in the upstream of Hun River and Taizi River as well as the meteorological data from the Qingyuan, Xinbin, and Benxi County stations, Northeast China in 1998-2007, a distributed hydrological model (DHS-VM) was applied to simulate the hydrological process in Hun-Tai basin. The scientific applicability of the model was validated, and the reference values of the most sensitive model parameters were provided. The simulated monthly runoff Nash-Suttclife coefficient (E value) for the source region of Hun River in calibration period (1998-2002) and validation period (2003-2007) was 0.9675 and 0. 8957, respectively, which could better reappear the monthly runoff process in this source region. The simulated monthly and annual runoff E values for the upstream of Taizi River were greater than 0.6, indicating that this model had good applicability in Hun-Tai basin, and the calibrated parameter scheme had a good reliability. This paper established a solid framework for the hydrological study over ungauged basin, and constructed a reasonable parameter scheme.

Leaf respiration is an important component of carbon exchange in terrestrial ecosystems, and estimates of leaf respiration directly affect the accuracy of ecosystem carbon budgets. Leaf respiration is inhibited by light; therefore, gross primary production (GPP) will be overestimated if the reduction in leaf respiration by light is ignored. However, few studies have quantified GPP overestimation with respect to the degree of light inhibition in forest ecosystems. To determine the effect of light inhibition of leaf respiration on GPP estimation, we assessed the variation in leaf respiration of seedlings of the dominant tree species in an old mixed temperate forest with different photosynthetically active radiation levels using the Laisk method. Canopy respiration was estimated by combining the effect of light inhibition on leaf respiration of these species with within-canopy radiation. Leaf respiration decreased exponentially with an increase in light intensity. Canopy respiration and GPP were overestimated by approximately 20.4% and 4.6%, respectively, when leaf respiration reduction in light was ignored compared with the values obtained when light inhibition of leaf respiration was considered. This study indicates that accurate estimates of daytime ecosystem respiration are needed for the accurate evaluation of carbon budgets in temperate forests. In addition, this study provides a valuable approach to accurately estimate GPP by considering leaf respiration reduction in light in other ecosystems.

[1] We tested a multilayered model that simulated half-hour canopy CO2 and H2O exchange of a temperate forest mixed with broadleaved trees and Korean pine. The variables input to the model for scaling the fluxes from leaf to canopy included the vertical profiles of height, canopy thickness, and leaf biomass of the five dominant tree species. The diurnal and seasonal patterns of modeled CO2 and H2O fluxes agreed with measured values well during the nonstressed periods, while the model showed overestimation during the water-stressed and high-temperature periods, which appeared infrequently in our study site. We showed a strong correlation between 20-layer daily modeled fluxes and eddy covariance measurements for CO2 (r2 = 0.734) and H2O (r2 = 0.785), during May to September 2003–2007. Different layered methods exerted influence on the radiation absorption within the canopy sublayers and hence on the CO2 and H2O flux outputs. CO2 and H2O fluxes based on the Gaussian 5-layered method were 8% and 1% lower than those based on the 20-layered method.

Phytoremediation using hyperaccumulators is a promising technique of removing soil pollutants. In the study, growth responses, cadmium (Cd) accumulation capability and physiological mechanisms of Lonicera japonica Thunb. under Cd stress were investigated. Exposed to 5 and 10 mg L(-1) Cd, the plants did not show any visual symptoms, furthermore, the height, dry biomass of leaves, roots and total and the chlorophyll (CHL) content were obtained different grade increase. When the concentration of Cd was up to 50 mg L(-1), the height, dry biomass of leaves and roots had not significant differences compared with the control. The indexes of tolerance (IT) were all above 0.8. The maintenance of high superoxide dismutase (SOD) and catalase (CAT) activities was observed along with the increased Cd concentration, suggesting strong internal detoxification mechanisms inside plant cells. After 21 days exposure to 25 mg L(-1) Cd, stem and shoot Cd concentrations reached 344.49+/-0.71 and 286.12+/-9.38 microg g(-1) DW, respectively and the plant had higher bioaccumulation coefficient (BC) and translocation factor (TF). According to these results, it was shown L. japonica had strong tolerance and accumulation capability to Cd, therefore it is a potential Cd-hyperaccumulator.

To improve the accuracy of the moderate resolution imaging spectroradiometer (MODIS) gross primary production (GPP) algorithm, it is critical to evaluate MODIS GPP production for different land cover types using ground-based measurements. In this paper the MODIS primary production products (MOD17) is evaluated by using site-specific input parameters to the algorithm and compared to the results of eddy covariance measurements over an old-growth forest. Direct comparisons suggest that 8-day GPP predicted by the standard MODIS algorithm was highly correlated with flux tower based GPP (r2 = 0.77, P

By using Granier's thermal dissipation probe, the sap flow velocity of the poplars in agroforestry system in west Liaoning was continuously measured, and the microclimate factors were measured synchronously. Dislocation contrast method was applied to analyze the sap flow velocity and corresponding air temperature, air humidity, net radiation, and vapor pressure deficit to discuss the time lag effect between poplar' s sap flow velocity and microclimate factors on sunny days. It was found that the poplar's sap flow velocity advanced of air temperature, air humidity, and vapor pressure deficit, and lagged behind net radiation. The sap flow velocity in June, July, August, and September was advanced of 70, 30, 50, and 90 min to air temperature, of 80, 30, 40, and 90 min to air humidity, and of 90, 50, 70, and 120 min to vapor pressure deficit, but lagged behind 10, 10, 40, and 40 min to net radiation, respectively. The time lag time of net radiation was shorter than that of air temperature, air humidity, and vapor pressure. The regression analysis showed that in the cases the time lag effect was contained and not, the determination coefficients between comprehensive microclimate factor and poplar's sap flow velocity were 0.903 and 0.855, respectively, indicating that when the time lag effect was contained, the determination coefficient was ascended by 2.04%, and thus, the simulation accuracy of poplar's sap flow velocity was improved.

Based on the measurements of eddy flux and micrometeorological factors, this paper analyzed the diurnal and seasonal variations of energy balance over Horqin meadow. The results showed that annual energy balance ratio (EBR) of the eddy covariance system was 0.77, and EBR was biggest in growing season, middle in bare soil period and smallest in snow-covered period. Diurnal variations of energy components all presented bell-shaped curves. The peak of net radiation appeared around 12:00 and peaks of other components slightly lagged. Seasonal variation of net radiation presented a single-peak curve, and the annual average was 5.71 MJ x m(-2) x d(-1). Seasonal variation of latent heat flux was similar to that of net radiation, and the annual average was 2.84 MJ x m(-2) x d(-1). Seasonal variation of sensible heat flux presented a double-peak curve, and the peaks appeared in April and September, respectively. Annual averaged sensible heat flux was 1.87 MJ x m(-2) x d(-1). Maximum soil heat flux (3.47 MJ x m(-2) x d(-1)) appeared in April, and the soil heat flux became negative after September. Annual budget ratios of energy components presented a decreasing order of latent heat flux, sensible heat flux and soil heat flux, which accounted for 49.8%, 35.8% and 3.1% of net radiation, respectively. Seasonal variation of Bowen ratio (beta) presented a 'U' shape, and the annual average was 1.61. beta was small (0.18) and relatively stable in growing season, while it was large (2.39) and fluctuated severely in non-growing season.

To understand the mechanisms of soil respiration and accurately estimate its magnitude are the crucial basis of evaluating global carbon balance. However, the previously built soil respiration forecast models usually neglect the physiological processes that photosynthesis supplies substrates for rhizospheric respiration, leading to the defect in evaluating the mechanisms of soil respiration. This paper summarized the research progress on the mechanisms of photosynthetic regulation and control of soil respiration, introduced the related main research methods, and discussed the existing problems and research hotspots.