| As the principal part of terrene ecosystem, forest contributed an important rule for climate accommodating and water resource equilibrium. Grasping the effect of forest individual and colony water transfer characteristic to regional water balance is the importance references to appraising forest ecological effect. For a long time, due to low awareness of water consumption and transportation law for plants, supervising of standing forest in existence was considered blindly. Shortage in forest resource mass and quality can not satisfy the need of ecological environmental and water resource balance for agriculture and industry and other social affairs'sustainable development and cuased a serious conflict between now day's demand and nature state of environment degradation and water resource sparseness. In order to evaluate Quercus acutissima's water transportation and consumption characteristic in the SPAC interface, namely soil-plant-atmosphere continua, and fulfill water consumption scaling-up method form single tree to stand scale, and provide theoretical foundation for forest construction adjustment, the hilly terrain second growth principal species of Quercus acutissima was investigated in this paper.By using pot experiment and on forest spot research, water transportation characteristics and water consumption controlling mechanisms of seedlings and wood trees of Quercus acutissima were researched. Many instrument and equipment was used in this research: CIRAS-2 photosynthesis system and TPS-1 for leaf transpiration and stomatal conductance adjustment measurement, Delta-T auto-moveable climatic station for all-weather forest air and soil environmental eco-factors measurement, Thermal Dissipation Probe (TDP-30) for single tree sapwood flow's temporal-and-spatial fluctuation, PSΨPRO micro-dew point voltage meter for soil and leaf water potential, AQUA-TEL-TDR time and space echo-meter for soil moisture measurement, Flashing Method and a set of developed instrument for branch tissue water conductance measurement and embolism vulnerability analysis, and stem water were measured by these methods. Tree's leaf transpiration and water conductance and its influence factors were measured and analyzed, and tree's self biological water unsteady transportation and consumption mechanisms, such as stomatal adjustment, tissue water capacitance, sapwood water conductance tissue structure, sap flow temporal-and-spatial fluctuation, and sapwood embolism vulnerability, tissue and stem water capacitance and so on was analyzed.With hand control conditions, leaf and soil water potential of potted seedlings in response to drought stress was researched. The results showed that soil and leaf water potential dropped along with drought stress degree. Leaf transpiration velocity ,stomatal conductance, stomatal density, stomatal opening, length and minor axis of stomata daily fluctuation were measured during drought stress period. Correlationship between leaf transpiration velocity, stomatal conductance and environmental factors was analysised.On single tree level, sap flow temporal-and-spatial variation law, daily fluctuation and seasonal variations of Quercus acutissima were researched. The characteristics of sap flow daily fluctuation were curved by"start-up, rose, peak value, descent, trough". Sap flow seasonal variations of Quercus acutissima was expressed by sap flow velocity: Summer > Springtime > Autumn. Sap flow velocity and fluid-in-flux of Quercus acutissima in different trunk height,different stem orientations,different stem diameters were compared. The water delivery dynamic in daily parts of Quercus acutissima was analyzed with statistical methods. Spring trunk poundage fluctuated sharply and extended greatly than that in autumn. The relative trunk water restoring time in spring was about 20 hours, and 10~12 hours longer than that in autumn.The influence of environmental factors to single tree sap flow of Quercus acutissima was analyzed based on the incorporation of dynamic variation environmental factors inside of standing forest. The influence of different depth of soil temperature and relative humidity to sap flow velocity and density of Quercus acutissima differed in seasons. There were a difference between the influence of air temperature and relative humidity to sap flow velocity and fluid-in-flux of Quercus acutissima. In lower wind speed, sap flow velocity increased quickly along with wind speed, but when wind speed reached 1.2 m / s, sap flow velocity augmented slowly. It was significant that the influence of solar radiation and net radiation to sap flow. The correlation between solar radiation, net radiation and sap flow velocity, density were in level of significance, so solar radiation and net radiation were the main effect environmental factors to sap flow. The influence of atmosphere saturation vapor pressure deficient to sap flow was smaller.The daily rhythm of environmental factors such as TBB, TPa, RHa in the stand were regularly and similar to sap flow significantly, not like the TPs, RHs which had no significant correlations to sap flow during measuring period. TBB showed positive and highest respond to the SFV. The influence of TPa and RHa to SFV was smaller than TBB, with positive and negative correlation to SFV respectively.Based on the curve estimate of sap flow characteristic of Quercus acutissima using manifold curve model, the simulation curvilinear equation of environmental factors to sap flow were founded, but the availability of these equations differed each other. The models of relative humidity of air and net radiation to sap flow were tested and verified. We build prediction cubic equation to fit the relationship of air relative humidity to sap flow velocity and density. Their expressions were: y = 0. 0045-8.0E-05×RHa+3.3E-09×RHa~3, y = 0. 0045-8.0E-05×RHa+3.3E-09×RHa~3.There was a certainty error existed the relationship between air relative humidity and sap flow velocity. The effect of the simulation of air relative humidity to sap flow density was creditable. The simulation equation of net radiation with sap flow velocity and sap flow density was adopted as follows: y = 0 .0002+2.2E-06×TBB-3.0E-09×TBB2 +3.1E-12×TBB~3, y = 21 .7665+0.2030×TBB-0.0003×TBB2 +2.7E-07×TBB3. The predictor based on cubic equation agreed with reasonably measured value very well.The unsteady sap flow velocity and density were existed in different seasons and different trunk height. In different seasons, the acute fluctuation and relative stabilization phase of sap flow velocity and density were different. The amplitude and frequency of fluctuation of sap flow differed greatly by comparing the postponed step-out time analysis. But on the whole, the unsteady state course of sap flow characteristics of Quercus acutissima was a type curve of reverse"V"in days and"V"at night.The microstructural difference of Quercus acutissima root, twig and leaf were compared, including vessel diameter, vessel density, distribution and relatively conduction area. Twigs' hydraulic conductivity and xylem embolism vulnerability of Quercus acutissima was researched and compared during the period of water potential of twigs dropping in different seasons. Twig's water capacitance characteristics of Quercus acutissima seedling in different seasons, trunk water capacitance, daily fluctuation of hydraulic transportation resistance and it's influence factors were researched. The correlation of sap flow characteristics and transpiration velocity of Quercus acutissima stem to water potential in the interface of SPAC were smaller. The influence of water potential in the SPAC interface to system resistance was very bigger. The correlation index of soil water potential to system resistance was the biggest with -0.709 in level of significance. The influence of root system water potential taken second place, with correlation index of -0.634. The correlation index only to -0.583 was the least influence of leaf water potential to system resistance.The diurnal variation of trunk hydraulic capacitance of Q. acutissima assumed uni-model curve in unsteady environment. In early morning, the time average of trunk hydraulic capacitance was smaller, with 0.41 kg·MPa-1. Subsequently, the trunk hydraulic capacitance was increasing and mounted up to maxima 1.64 kg·MPa-1 all day along at 10:00~11:00 o'clock. In afternoon, the time average of trunk hydraulic capacitance was decreasing slowly. At 17:00~18:00 pm, the trunk hydraulic capacitance went down 0.83 kg·MPa-1. The effect of trunk hydraulic capacitance on sap flow velocity and density was significant, with the correlation coefficient of 0.925, 0.924 respectively. The correlation between trunk hydraulic capacitance and leaf transpiration taken second place compared to the correlation of trunk hydraulic capacitance to sap flow, with correlation coefficient of 0.802.The temporal dynamic response of measured stem flow to main climatic forcing was exploited using the cross-correlation analysis, Correlations over a range of time lag -100 min to +180 min. For TBB versus SFV, correlation ranged from 0.265 to 0.944; whereas from 0.409 to 0.869 and form -0.406 to -0.159 for TPa versus SFV and RHa versus SFV, respectively. The lag time about 80 min,20 min,30 min was detected between SFV versus TBB ;whereas, TPa lags SFV by 60 min,130 min,110 min and RHa lags SFV by 170 min,160 min,90 min in upper trunk, mid-trunk, lower trunk, respectively. Studies suggested that patterns of daily and diurnal SFV fluctuation were different in three height of trunk. The main environmental factors affected sap flow were TBB, TPa, RHa, with positive and negative correlation to SFV, although their effect were not similar to each other. The correlation of sap flow respond to environmental factors indicated substantially that there were lag effect between SFV and synchronization data of TBB, TPa, RHa by cross-correlation analysis.
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