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Zhuang J.-J.,Chinese Academy of Forestry | Zhuang J.-J.,Nanjing Forestry University | Zhang J.-S.,Chinese Academy of Forestry | Zhang J.-S.,Nanjing Forestry University | And 5 more authors.
Forest Research | Year: 2016

Objective: To investigate the diurnal and seasonal variation of CH4 fluxes in different weather conditions, and explore the effects of soil and meteorological factor on CH4 fluxes in black locust forest soil. Method: The automatic observation system with the near infrared laser and infrared laser analysis composite technology was used to measure the CH4 fluxes of soil in Robinia pseudoacacia L. plantation in low hilly land of north China from October 2014 to April 2015. Meanwhile, the atmospheric temperature and relative humidity, soil temperature and soil water content (5 cm), global radiation and precipitation were concurrently measured. The principal component analysis and stepwise regression analysis were used to analyze the relationship among the factors and determine the main factor of soil CH4 flux. Result: (1) The soil of R. pseudoacacia plantation was the important atmospheric CH4 sink during the non-growing season with the range from-0.15 to-2.34 nmol·m-2·s-1. The diurnal variation of CH4 fluxes showed diurnal characteristics of "V-shape",and had higher absorption capacity in a clear day (-0.78 nmol·m-2·s-1) but lower in cloudy (-0.61 nmol·m-2·s-1), rainy or snowy day (-0.58 nmol·m-2·s-1). From November 2014 to January 2015, a gradual decline in the absorption capacity of soil was found. The remained fairly low until the spring when the soil started thawing. The soil CH4 absorption capacity reached the maximum (-2.34 nmol·m-2·s-1) in March 2015. (2) There was a significant negative correlation relationship between soil CH4 fluxes and atmospheric temperature, soil temperature.The soil CH4 fluxes was positively correlated with atmospheric relative humidity. In March and April 2015, the most significant positively correlation was observed between CH4 fluxes and global radiation. (3) The factors of atmospheric temperature and relative humidity became the leading elements in terminal growth and winter while the atmospheric temperature and soil temperature (5 cm in depth) were the primary factors of soil CH4 fluxes in early growing season. Conclusion: The R. pseudoacacia forest soil was the sinks of atmospheric CH4 during non-growing season. The absorption capacity of CH4 was the weakest in early non-growing season, while the absorption capacity of the soil gradually increased at the end of non-growing season. In the early period, the soil CH4 fluxes were mainly affected by atmospheric temperature and relative humidity. In the latter period, the soil CH4 fluxes were influenced by air temperature and soil temperature. © 2016, Chinese Academy of Forestry. All right reserved. Source


Liu Q.-X.,Chinese Academy of Forestry | Meng P.,Chinese Academy of Forestry | Meng P.,Key Laboratory of Tree Breeding and Cultivation | Zhang J.-S.,Chinese Academy of Forestry | And 6 more authors.
Chinese Journal of Applied Ecology | Year: 2012

In order to understand the accuracy of Granier's thermal dissipation method in measuring tree water consumption, a comparative study was made from May to June, 2010. The sap flow density of potted Platycladus orientalis was measured with thermal dissipation probe, which was compared with the whole-plant gravimetric measurement. There were significant linear relationships (R2 >0.825) between the sap flow velocity in both north and south directions of P. orientalis measured by thermal dissipation probe and the transpiration rate measured by gravimetric method. The average daily sap flux in the north and south directions of P. orientalis were 10.6% and 15.1% lower than the daily average transpiration of P. orientalis, respectively, but the differences were not significant. Therefore, Granier's method had high reliability in the measurement of P. orientalis transpiration at daily scale, though the large temperature fluctuation between day and night could result in a lower daily sap flux than daily transpiration. Source


Sun S.-J.,Chinese Academy of Forestry | Meng P.,Chinese Academy of Forestry | Zhang J.-S.,Chinese Academy of Forestry | Jia C.-R.,Dagouhe National Forest Farm | Ren Y.-F.,Dagouhe National Forest Farm
Chinese Journal of Applied Ecology | Year: 2012

By using Circumference Dendrometer 2 (DC2), this paper studied the diurnal variation of trunk diameter in Quercus variabilis plantation at the south aspect of Taihang Mountains. During seasonal drought, the diurnal variation of Q. variabilis trunk diameter was quite evident. The time of the diameter shrinkage followed the start-up time of sap flow, but the appearance of the minimum trunk diameter lagged behind the maximum sap flow flux about 3-4 h. The maximum daily shrinkage (MDS) value of the trunk diameter presented a trend low-high-low, being significantly correlated with the diurnal differences of cumulative sap flow flux and leaf water potential and having a siGnificant quadratic relationship with soil moisture content. The MDS value was affected by the varia- tions of meteorological factors, being significantly correlated with the diurnal variations of air temperature, vapor pressure deficit, and relative humidity, but less correlated with the diurnal variation of solar radiation. After successive precipitation, soil moisture content was no longer the limiting factor of the diurnal variation of Q. variabilis trunk diameter. The MDS value had less correlations with the diurnal differences of cumulative sap flow flux, leaf water potential, soil moisture content, and other meteorological factors. Stepwise regression analysis indicated that the soil moisture content and air temperature in seasonal drought and rain seasons were the key factors affecting the diurnal variation of Q. variabilis trunk diameter. Source


Tian C.,Chinese Academy of Forestry | Tian C.,Nanjing Forestry University | Meng P.,Chinese Academy of Forestry | Meng P.,Nanjing Forestry University | And 8 more authors.
Chinese Journal of Applied Ecology | Year: 2015

The seasonal characteristics of δD and δ18O in precipitation and the influence factors were studied in the Xiaolangdi Reservoir area at the eastern monsoon region of China. The precipitation samples and the corresponding meteorological data were collected between April and October from the year 2011 to 2014. The local meteoric water lines (LMWL) of different seasons were established, and the water vapor sources in different seasons were investigated. The results showed that the δD and δ18O in precipitation exhibited an extremely wide range and a distinct seasonal variation, and they were enriched in the spring, and depleted in the fall. The δD and δ18O values showed negative correlations with the amount of precipitation from April to October and the fall, respectively. The δD values and the mean air temperature showed a negative correlation from April to October, but showed no correlation in seasonal precipitation. Both the slopes of LMWL and excess deuterium (d values) of precipitation were the smallest in the summer, and the largest in the fall. The results of air mass back trajectories of seasonal precipitation using the HYSPLIT model indicated a dominant effect of southeast and southwest maritime monsoon air masses in the summer and the coinfluence of continental and oceanic monsoons air masses in the spring and fall in the study area. © 2015, Editorial Board of Chinese Journal of Applied Ecology. All right reserved. Source


Chen P.,Chinese Academy of Forestry | Meng P.,Chinese Academy of Forestry | Zhang J.-S.,Chinese Academy of Forestry | He C.-X.,Chinese Academy of Forestry | And 2 more authors.
Chinese Journal of Applied Ecology | Year: 2014

Growth characteristics, stable carbon isotope discrimination (Δ13C), water use efficiency (WUE), and their correlation of Cassia obtusifolia and Isatis indigotica were measured at three soil water levels, i. e., 30%, 50% and 75% of field water holding capacity (FWHC), and at three growth stages. The growth indices of the two medicinal plants at 75% of FWHC were higher than those at 30% and 50% of FWHC, suggesting that the two medicinal plants could obtain high production under sufficient moisture condition. The Δ13CA(aboveground biomass-based Δ13C) and Δ13CT (total biomass-based Δ13C) decreased, and the WUEA (aboveground biomass-based WUE) and WUET (total biomass-based WUE) of C. obtusifolia and I. indigotica increased with the increasing degree of drought stress. The growth indices of the two medicinal plants had little difference in the different water treatments, which indicated that the two medicinal plants were insensitive to drought stress. Water use efficiency of I. indigotica had significant negative relationships with aboveground biomass and total biomass, while that of C. obtusifolia had a significant positive correlation with the root/shoot ratio. Source

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