Variation Characteristics of Main Climate Factors in the Upstream of Wei River in Recent 39 Years

Wei River is an important river which affects the industrial and agricultural production,people's life in Guanzhong district of Shaanxi and the east of Gansu.To study the variation characteristics of main climate factors in recent 39 years in the upstream of Wei River,we analyzed the variation characteristics of climate factors by using the data in 11 meteorological stations in the upstream basin of Wei River during 1971-2009.The results showed that the precipitation presented the decline trend in the basin,and the temperature rose in 0.3 ℃/10 a trend.The temperature increase trend was 0.4 ℃/10 a in winter,spring and wasn't obvious in summer,autumn.The potential evapotranspiration presented the yearly increase trend in recent years.The precipitation decreased,and the temperature rose.Moreover,the potential evapotranspiration strengthened.It wasn't favorable for the healthy run of ecological system in the upstream,downstream basins and aggravated the shortage degree of water resources.

Drought Change Trend Using MODIS TVDI and Its Relationship with Climate Factors in China from 2001 to 2010

Changes in drought trends and its relationship with climate change in China were examined in this study. The temperature vegetation drought index （TVDI） datasets recorded during 2001 to 2010 in China were constructed by using the moderate-resolution imaging spectroradiometer （MODIS） data, and the temporal and spatial variations in drought were analyzed. In addition, the mean temperature, mean precipitation, mean relative humidity, and mean sunshine duration data collected from 557 local weather stations in China were analyzed. The relationships between drought and these climate factors were also analyzed by using correlation analysis and partial correlation analysis. Changes in drought tendency were shown to differ among four regions throughout the country. The lfuctuations in climate in the regions of northeastern China, Qinling-Huaihe, and central Qinghai were caused by the increase in soil moisture, and that in southern Tibet was caused by the intensiifcation of drought. Meteorological factors exhibited varied effects on drought among the regions. In southern China, the main inlfuential factor was temperature;other factors only showed minimal effects. That in the northern and northwestern regions was sunshine duration, and those in the Qinghai-Tibet Plateau were relative humidity and temperature.

Impact of climate factors on runoff in the Kaidu River watershed:path analysis of 50-year data

Runoff formation is a complex meteorological-hydrological process impacted by many factors,especially in the inland river basin.Based on the data of daily mean air temperature,precipitation and runoff during the period of 1958-2007 in the Kaidu River watershed,this paper analyzed the changes in air temperature,precipitation and runoff and revealed the direct and indirect impacts of daily air temperature and precipitation on daily runoff by path analysis.The results showed that mean temperature time series of the annual,summer and autumn had a significant fluctuant increase during the last 50 years（P 0.05）.Only winter precipitation increased significantly（P 0.05） with a rate of 1.337 mm/10a.The annual and winter runoff depthes in the last 50 years significantly increased with the rates of 7.11 mm/10a and 1.85 mm/10a,respectively.The driving function of both daily temperature and precipitation on daily runoff in annual and seasonal levels is significant in the Kaidu River watershed by correlation analysis.The result of path analysis showed that the positive effect of daily air temperature on daily runoff depth is much higher than that of daily precipitation in annual,spring,autumn and winter,however,the trend is opposite in summer.

Relative importance of climate factors and human activities in impacting vegetation dynamics during 2000–2015 in the Otindag Sandy Land,northern China

In recent years, there has been increasing research interests in differentiating the relative importance of climate factors and human activities in impacting vegetation dynamics. In this study, based on residual trend method, we used MOD13A3（MODIS vegetation index product）, MCD12Q1（MODIS land cover product） and meteorological datasets to differentiate the relative importance of climate factors and human activities in impacting vegetation dynamics during 2000–2015 in the Otindag Sandy Land, northern China. Results show that during the study period（2000–2015）, the overall vegetation condition had improved in the Otindag Sandy Land. The driving forces of vegetation dynamics differed spatially in the whole study area over the study period. The area with vegetation degradation solely resulted from human activities accounted for 8.23% of the study area, while the area with vegetation degradation resulted from others（including climate factors and combination of climate factors and human activities） occupied 1.53%. The area with vegetation recovery benefitted from human activities occurred over 26.02% of the study area; the area benefitted from climate factors accounted for 23.69%; and the area benefitted from both climate factors and human activities occupied 37.74%. All in all, impacts of climate factors and human activities on vegetation dynamics varied at the county/city/banner scales and locality-specific measures should be adopted to protect the environments.

Changes in Climate Factors and Extreme Climate Events in South China during 1961-2010

Daily climate data at 110 stations during 1961-2010 were selected to examine the changing characteristics of climate factors and extreme climate events in South China. The annual mean surface air temperature has increased significantly by 0.16℃ per decade, most notably in the Pearl River Delta and in winter. The increase rate of the annual extreme minimum temperature (0.48℃ per decade) is over twice that of the annual extreme maximum temperature (0.20℃ per decade), and the increase of the mean temperature is mainly the result of the increase of the extreme minimum temperature. The increase rate of high-temperature days (1.1 d per decade) is close to the decrease rate of low-temperature days (-1.3 d per decade). The rainfall has not shown any significant trend, but the number of rainy days has decreased and the rain intensity has increased. The regional mean sunshine duration has a significant decreasing trend of -40.9 h per decade, and the number of hazy days has a significant increasing trend of 6.3 d per decade. The decrease of sunshine duration is mainly caused by the increase of total cloud, not by the increase of hazy days in South China. Both the regional mean pan evaporation and mean wind speed have significant decreasing trends of -65.9 mm per decade and -0.11 m s-1 per decade, respectively. The decrease of both sunshine duration and mean wind speed plays an important role in the decrease of pan evaporation. The number of landing tropical cyclones has an insignificant decreasing trend of -0.6 per decade, but their intensities show a weak increasing trend. The formation location of tropical cyclones landing in South China has converged towards 10-19°N, and the landing position has shown a northward trend. The date of the first landfall tropical cyclone postpones 1.8 d per decade, and the date of the last landfall advances 3.6 d per decade, resulting in reduction of the typhoon season by 5.4 d per decade.

Characteristics of Accumulative Potato Biomass in Different Sowing Dates and Their Relationships with the Climate Factors in Tianshui City

[Objective] The aim was to study the characteristics of accumulative potato biomass in different sowing dates and their relationships with the climate factors in Tianshui City.[Method] Based on the potato sowing experiment by installments in Tianshui agrometeorological experiment station in 2009,the potato's growth periods in every sowing date were contrasted with the average sowing period.Moreover,the climate resources' occupied amounts,the accumulative progresses of tuber's fresh biomass in every growth period were contrasted with the average sowing period.[Result] The results showed that the days of whole growth period in every sowing date tended to be same with the average period.The accumulative temperature's occupied amounts of every critical temperature had little difference,but the solar radiation and precipitation had great difference.The nonlinearity correlation between tuber's fresh biomass accumulation and the accumulative temperature (≥10℃) was obvious.When the accumulative temperature(≥10℃) was about 1 100℃,it was the turning point which the accumulative velocity of tuber's fresh biomass changed.The accumulation of tuber's fresh biomass in every sowing date had little difference before the inflorescence formation period.After the inflorescence formation period,the accumulative velocity of potato tuber's fresh biomass in the sowing date which was 7 days later than the average sowing period was greater than other sowing dates.[Conclusion] The optimum sowing date of potato should be in the end of early April.It had the negative effects to promote potato's yield by sowing early and too late.

Effects of climate factors on the height increment of poplar protec-tion forest in the riverbank field

Based on the data of stand investigation and stem analysis, the effects of climate factors on the poplar protection forest increment in the riverbank field of the Dalinghe and Xiaolinghe rivers of Liaoning Province, China were studied by step-wise regression procedure and grey system theories and methods. A regression model reflecting the correlation between the height increment of poplar protection forest and climatic factors was developed. The order of grey relevance for the effect of climatic factors on the height increment of poplar protection forest is: light>water>heat, and it could be interpreted that the poplar increment was mainly influenced by light factor, water factor, and heat factor. This result will provide scientific basis for the in-tensive cultivation and regeneration of the poplar protection forest in riverbank field in similar regions in China.

Changes in Climate Factors and Their Impacts on Wind Erosion Climatic Erosivity in Farming-pastoral Zone of Northern China

Climate change can affect wind erosion power and hence induce changes in wind erosion rates.In this study,the wind erosion climate factor(C-factor),proposed by the Food and Agriculture Organization of the United Nations,was used to assess the impact of changes in climate on wind erosion climatic erosivity.The Mann-Kendall test was employed to detect trends in the C-factor during the period of 1961–2017 in the farming-pastoral zone of northern China.Sensitivity analysis was used to determine the sensitivity of the C-factor to changes in key climate factors.Furthermore,a comparison of the contributions of different climate factors was carried out to understand their impact on changes in the C-factor.The results indicated that most of the surveyed region exhibited decreasing trends in wind speed at a confidence level of 90%,while maximum and minimum temperatures showed increasing trends throughout the study area.As a consequence of decreasing wind speed,the annual C-factor exhibited significant decreasing trends,with a mean slope of–0.58/yr.Seasonal analysis revealed that in most regions,the changes in the C-factor had significant decreasing trends in spring,winter,and autumn,while in more than two-thirds of the study area,no significant change trends in the C-factor were detected in summer at a confidence level of 90%.Sensitivity analysis showed that the C-factor was most sensitive to wind speed,and that the sensitivity coefficients from July to September were much higher than those in other months.Contribution analysis revealed that,for most stations,wind speed(with greater values of sensitivity coefficients)was the dominant factor in the change of C-factor,while for some stations,the minimum temperature made the most contribution to the C-factor’s change due to its dramatic changes during the study period.Although the minimum temperature sensitivity coefficient was the lowest of all the sensitivity coefficients,it is urgent to evaluate the expected impact of minimum temperature due to its possible changes in the future.

Assessing the Effect of Climate Factors on Dengue Incidence via a Generalized Linear Model

Changes in climate factors such as temperature, rainfall, humidity, and wind speed are natural processes that could significantly impact the incidence of infectious diseases. Dengue is a widespread disease that has often been documented when it comes to the impact of climate change. It has become a significant concern, especially for the Malaysian health authorities, due to its rapid spread and serious effects, leading to loss of life. Several statistical models were performed to identify climatic factors associated with infectious diseases. However, because of the complex and nonlinear interactions between climate variables and disease components, modelling their relationships have become the main challenge in climate-health studies. Hence, this study proposed a Generalized Linear Model (GLM) via Poisson and Negative Binomial to examine the effects of the climate factors on dengue incidence by considering the collinearity between variables. This study focuses on the dengue hot spots in Malaysia for the year 2014. Since there exists collinearity between climate factors, the analysis was done separately using three different models. The study revealed that rainfall, temperature, humidity, and wind speed were statistically significant with dengue incidence, and most of them shown a negative effect. Of all variables, wind speed has the most significant impact on dengue incidence. Having this kind of relationships, policymakers should formulate better plans such that precautionary steps can be taken to reduce the spread of dengue diseases.

Solanum lycopersicum: Novelties for Climate Factors and Its Agronomic Management for High Yields

The intensive production of vegetables such as tomatoes depends on various strategies to achieve high yields.Purpose of this manuscript is to provide scientific and technological strategies for the intensive production of tomato or other vegetables in mega-production factories. However, with the advancement of knowledge, new improvements in the strategies will be incorporated. We have carried out research related to growth and yield variables in S. Lycopersicum. From this research we have worked on the intensive production of this noble vegetable at an industrial level. The results obtained are improvements in the production system. The improvements include the selection of the appropriate variety, germination and development of seedlings in a certified nursery. Trans-plantation in soil or hydroponics. The conditions of nutrient applications from the irrigation head system. The ventilation system and monitoring of climatic factors both day and night (temperature and relative humidity). Monitoring of macro- and micronutrients in the plant system, including Ca, K, Fe, and Zn. Soil fertility analyzes should include: primary and secondary macronutrients (ppm), organic matter (OM), EC, pH, bulk density (BD), and cation exchange capacity (CEC). The nutritional diagnosis to confirm ranges of sufficiency. As a tool in plant nutrition programs, foliar application can include biostimulants and growth regulators. The foregoing can be considered strategies for the integral management of the tomato crop.

Effects of soil nutrients and climate factors on belowground biomass in an alpine meadow in the source region of the Yangtze-Yellow rivers, Tibetan Plateau of China

Improving our knowledge of the effects of environmental factors （e.g. soil conditions, precipitation and temperature） on belowground biomass in an alpine grassland is essential for understanding the consequences of carbon storage in this biome. The object of this study is to investigate the relative importance of soil nutrients and climate factors on belowground biomass in an alpine meadow in the source region of the Yangtze and Yellow rivers, Tibetan Plateau. Soil organic carbon （SOC）, total nitrogen （TN） and total phosphorous （TP） contents and belowground biomass were measured at 22 sampling sites across an alpine meadow on the Tibetan Plateau. We analyzed the data by using the redundancy analysis to determine the main environmental factors affecting the belowground biomass and the contribution of each factor. The results showed that SOC, TN and TP were the main factors that influenced belowground biomass, and the contribution of SOC, TN and TP on biomass was in the range of 47.87%-72.06% at soil depths of 0-30 cm. Moreover, the combined contribution of annual mean temperature （AMT） and mean annual precipitation （MAP） on belowground biomass ranged from 0.92% to 4.10%. A potential mechanism for the differences in belowground biomass was caused by the variations in soil nitrogen and phosphorous, which were coupled with SOC. A significant correlation was observed between MAP and soil nutrients （SOC, TN and TP） at the soil depth of 0-10 cm （P〈0.05）. We concluded that precipitation is an important driving force in regulating ecosystem functioning as reflected in variations of soil nutrients （SOC, TN and TP） and dynamics of belowground biomass in alpine grassland ecosystems.

The role of climate factors in geographic variation in body mass and wing length in a passerine bird

Background: Geographic variation in body size is assumed to reflect adaptation to local environmental conditions. Although Bergmann's rule is usually sufficient to explain such variation in homeotherms, some exceptions have been documented. The relationship between altitude, latitude and body size, has been well documented for some vertebrate taxa during the past decades. However, relatively little information is available on the effects of climate variables on body size in birds.Methods: We collected the data of 267 adult Eurasian Tree Sparrow(Passer montanus) specimens sampled at 48 localities in China's mainland, and further investigated the relationships between two response variables, body mass and wing length, as well as a suit of explanatory variables, i.e. altitude, latitude, mean annual temperature(MAT), annual precipitation(PRC), annual sunshine hours(SUN), average annual wind speed(WS), air pressure(AP) and relative humidity(RH).Results: Our study showed that(1) although the sexes did not differ significantly in body mass, males had longer wings than females;(2) body mass and wing length were positively correlated with altitude but not with latitude;(3) body mass and wing length were negatively correlated with AP and RH, but not significantly correlated with WS. Body mass was positively correlated with SUN and inversely correlated with MAT. Wing length was not correlated with MAT in either sex, but was positively correlated with SUN and negatively correlated with PRC in male sparrows;(4) variation in body mass could be best explained by AP and SUN, whereas variation in wing length could be explained by RH and AP in both sexes. In addition, variation in male sparrows can be explained by SUN, WS and PRC but not in females.Conclusions: Two different proxies of body size, body mass and wing length, correlated with same geographic factors and different climate factors. These differences may reflect selection for heat conservation in the case of body mass, and for efficient flight in the case of wing length.

Relationship between multi-scale climate factors and performance of ecological engineering on the Loess Plateau, China

The long-term “Grain-to-Green Program” (GGP) on China’s Loess Plateau is a major global ecological engineering project which has significantly boosted vegetation renewal. Some studies have found that the rate of restoration is quite rapid during the implementation of ecological engineering, however, the influence of multi-scale climatic conditions on the performance of ecological engineering is unclear. In this study, multiple sources of remote sensing data were used to estimate the dynamics of vegetation structural and functional indicators, water-related local climatic factors, and atmospheric circulation factors. These datasets were also used to detect possible causes for vegetation restoration on the Loess Plateau over the past 20 years. The results show that widespread increases in rates of normalized difference vegetation indexes (NDVI), leaf area indexes (LAI), gross primary production (GPP), and aboveground biomass carbon (ABC) during 2000–2016 were significantly higher than before 2000. GPP was significantly correlated with rainfall and surface runoff on a monthly scale, and there were significant positive correlations between GPP and atmospheric circulation. Our results demonstrate that both vegetation structural and functional indicators rapidly increase, and ecological engineering greatly accelerated vegetation restoration after 2000. Local climatic conditions and atmospheric circulation patterns enhance vegetation growth and impact of ecological engineering.

Effects of Climate Factors in Greenhouses on the Growth Development and Quality of Houttuynia cordata Thunb.

[Objectives]This study was conducted to demonstrate whether greenhouse planting can solve the problem of insufficient supply of fresh H.cordata Thunb.in winter and spring.[Methods]The effects of meteorological factors on the growth and quality of H.cordata Thunb.were analyzed.[Results]The highest temperature and lowest temperature in greenhouses were 6-12℃and 5-10℃higher than those in the open fields,respectively,and the average temperature difference between the greenhouses and the open fields was large in the early stage,but small in the late stage.The effective accumulated temperature≥10℃was 3463℃in the greenhouses and 2046℃in the open fields.Although the humidity in the open fields was higher than that in the greenhouses,the humidity in the greenhouses was relatively stable and that in the open field changed greatly.The light intensity of the greenhouses was lower than that of the open fields.In terms of the periods from film covering day to seedling emergence,seedling emergence to full emergence,and full emergence to crop closure,greenhouse planting was shortened by 47,11,and 5 d,respectively,compared with open field planting,but the period from crop closure to flowering was extended by 40 d.The plant height of the plants planted in the greenhouses reached 0.1 cm on January 7,while those planted in the open fields did not have seedlings until February 25,and the plant height,daily growth rate,yield and effective components in volatile oil of the plants planted in the greenhouses were significantly higher than those planted in the open fields.The growth,development and quality of H.cordata Thunb.reached the extremely significant or significant level with temperature,but had no significant correlation with humidity and light intensity,indicating that temperature had the greatest impact on the growth,development and quality of H.cordata Thunb.when planted in the greenhouses.[Conclusions]This study provides a theoretical basis for protected cultivation and explores new planting methods for the further development of its industry.

Modeling the Influence of Climate Factors on Malaria Transmission Dynamics in North Kordofan State, Sudan

Background: Despite great efforts by the government to control malaria in Sudan, the disease is the most significant human disease and was widespread in North Kordofan State. Morbidity and mortality of the disease are increasing in the State. Usually, the disease reached its peak after rainy season. This study aims to estimate the role of climate factors on malaria transmission dynamic by modeling the relationship between malaria cases and climatic variables, such as rainfall, relative humidity, and temperature, in Kordofan State. Methods: We used Pearson correlation coefficient and an ordinary least square method to assess this relationship. Results: The results show that there are statistically significant associations between malaria cases and rainfall, relative humidity, and minimum temperature (P-value < 0.001). The regression analysis results suggest that the appropriate model for predicting malaria incidence includes malaria cases lagged by one month, maximum temperature, and minimum temperature. This model explained 72% of the variance in monthly malaria incidence. Conclusion: The results of this study suggest that climatic factors have potential use for malaria prediction in the State.

Response of vegetation phenology to climate factors in the source region of the Yangtze and Yellow Rivers

Exploring the impact of climate factors on vegetation phenology is crucial to understanding climate–vegetation interactions as well as carbon and water cycles in ecosystems in the context of climate change.In this article,we extracted the vegetation phenology data from 2002 to 2021 based on the dynamic threshold method in the source region of the Yangtze and Yellow Rivers.Trend and correlation analyses were used to investigate the relationship between vegetation phenology and temperature,precipitation and their spatial evolution characteristics.The results showed that:(i)From 2002 to 2021,the multi-year average start of growing season(SOS),end of growing season(EOS)and length of growing season(LOS)for plants were concentrated in May,October and 4–6 months,with a trend of 4.9 days(earlier),1.5 days(later),6.3 days/10 a(longer),respectively.(ii)For every 100 m increase in elevation,SOS,EOS and LOS were correspondingly delayed by 1.8 days,advanced by 0.8 days and shortened by 2.6 days,respectively.(iii)The impacts of temperature and precipitation on vegetation phenology varied at different stages of vegetation growth.Influencing factors of spring phenology experienced a shift from temperature to precipitation,while autumn phenology experienced precipitation followed by temperature.(iv)The climate factors in the previous period significantly affected the vegetation phenology in the study area and the spatial variability was obvious.Specifically,the temperature in April significantly affected the spring phenology and precipitation in August widely affected the autumn phenology.

Response Differences of MODIS-NDVI and MODIS-EVI to Climate Factors

To evaluate and provide an appropriate theoretical direction for research into climate-vegetation interactions using meteorological station data at different time scales,we examined differences between the Normalized Difference Vegetation Index (NDVI)and Enhanced Vegetation Index (EVI)and their responses to climate factors. We looked for correlations between'data extracted from MOD13Q1 remote sensing images and meteorological station data for the two indexes.The results showed that even though NDVI and EVI are derived from the same remote sensing image,their response to climate factors was significantly different.In the same meteorological station,the correlation coefficients for NDVI,EVI and climate factors were different;correlation coefficients between NDVI,EVI and climate factors varied with meteorological station.In addition,there was a lag effect for responses of NDVI to average minimum temperature,average temperature,average vapor pressure,minimum relative humidity, extreme wind speed,maximum wind speed,average wind speed and average station air-pressure.EVI had a lag only for average minimum temperature,average vapor pressure,extreme wind speed,maximum wind speed and average station air-pressure.The lag period was variable,but most were in the -3 period.Different vegetation types had different sensitivities to climate.The correlation between meteorological stations and vegetation requires more attention in future research.

Impact of climate factors on contact rate of vector-borne diseases： Case study of malaria

Climate change influences more and more of our activities. These changes led to envi- ronmental changes which has in turn affected the spatial and temporal distribution of the incidence of vector-borne diseases. To establish the impact of climate on contact rate of vector-borne diseases, we examine the variation of prevalence of diseases according to season. In this paper, the goal is to establish that the basic reproductive number R0 depends on the duration of transmission period and the date of the first conta- mination case that was declared （to） in the specific ease of malaria. We described the dynamics of transmission of malaria by using non-autonomous differential equations. We analyzed the stability of endemic equilibrium （EE） and disease-free equilibrium （DFE）. We prove that the persistence of disease depends on minimum and maximum values of contact rate of vector-borne diseases.

Changes in Climatic Factors and Extreme Climate Events in Northeast China during 1961-2010

This study focuses on examining the characteristics of climate factors and extreme climate events in Northeast China during 1961- 2010 by using daily data from 104 stations, including surface air temperature, precipitation, wind speed, sunshine duration, and snow depth. Results show that annual mean temperature increased at a significant rate of 0.35℃ per decade, most notably in the Lesser Khingan Mountains and in winter. Annual rainfall had no obvious linear trend, while rainy days had a significant decreasing trend. So, the rain intensity increased. High-temperature days had a weak increasing trend, and low-temperature days and cold wave showed significant decreasing trends with rates of 3.9 d per decade and -0.64 times per decade, respectively. Frequency and spatial scope of low-temperature hazard reduced significantly. Warm days and warm nights significantly increased at 1.0 and 2.4 d per decade, while cold days and cold nights decreased significantly at -1.8 and -4.1 d per decade, respectively. The nighttime warming rate was much higher than that for daytime, indicating that nighttime warming had a greater contribution to the overall warming trend than daytime warming. The annual mean wind speed, gale days, and sunshine duration had significant decreasing trends at rates of-0.21 m s-1 per decade, -4.0 d per decade and -43.3 h per decade, respectively. The snow cover onset dates postponed at a rate of 1.2 d per decade, and the snow cover end date advanced at 1.5 d per decade, which leads to shorter snow cover duration by -2.7 d per decade. Meanwhile, the maximum snow depth decreased at -0.52 cm per decade. In addition, the snow cover duration shows a higher correlation with precipitation than with temperature, which suggests that precipitation plays a more important role in maintaining snow cover duration than temperature.

Diurnal and Seasonal Variations of CO2Fluxes and Their Climate Controlling Factors for a Subtropical Forest in Ningxiang

In this study, the diurnal and seasonal variations of CO2 fluxes in a subtropical mixed evergreen forest in Ningxiang of Hunan Province, part of the East Asian monsoon region, were quantified for the first time. The fluxes were based on eddy covariance measurements from a newly initiated flux tower. The relationship between the CO2 fluxes and climate factors was also analyzed. The results showed that the target ecosystem appeared to be a clear carbon sink in 2013, with integrated net ecosystem CO2exchange（NEE）, ecosystem respiration（RE）, and gross ecosystem productivity（GEP） of-428.8, 1534.8 and1963.6 g C m^-2yr^-1, respectively. The net carbon uptake（i.e. the-NEE）, RE and GEP showed obvious seasonal variability,and were lower in winter and under drought conditions and higher in the growing season. The minimum NEE occurred on12 June（-7.4 g C m^-2d^-1）, due mainly to strong radiation, adequate moisture, and moderate temperature; while a very low net CO2 uptake occurred in August（9 g C m^-2month^-1）, attributable to extreme summer drought. In addition, the NEE and GEP showed obvious diurnal variability that changed with the seasons. In winter, solar radiation and temperature were the main controlling factors for GEP, while the soil water content and vapor pressure deficit were the controlling factors in summer. Furthermore, the daytime NEE was mainly limited by the water-stress effect under dry and warm atmospheric conditions, rather than by the direct temperature-stress effect.