Dagou he National Forest Farm

Shuangqiao, China

Dagou he National Forest Farm

Shuangqiao, China
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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.
Forest Research | Year: 2015

By using stable isotope techniques, the Platycladus orientalis grown on the rocky hilly area of North China were chosen to investigate air temperature, soil temperature, moisture and δD value in order to discuss the effect of seasonal rainfall on soil temperature, moisture and water movement. The results indicated that: the soil temperature following rainfal decreased first and then increased in the rainy season, and decreased with the increases of depths, whereas in the early dry season the temperature continued to decrease but increased with the depth. No matter in the rain or dry season, the soil moisture increased at first and then decreased after the rain, but dropped with the depth of soil. In rain season, when the early soil moisture was low, the low intensity rainfall could further increase the moisture of surface and deep soil and made the water δD value deplete, which showed rainfall could recharge the surface and middle soil. However, in prior plentiful rainfall period, low intensity rainfall could further increased the deep soil moisture, and all the soil water δD value were depleted, which indicated that rainfall could rapidly infiltrate into the deep soil. High intensity rainfall increased all the soil moisture and the increments had small differences, meanwhile all the water δD value were depleted, which showed that rainfall could quickly infiltrate into all the soil. In the early dry season, low intensity rainfall may further increase the surface soil moisture. Even if the prior soil moisture were low, the soil water δD value were all depleted, which pointed that rainfall could rapidly infiltrate into the deep soil and further recharged groundwater. Directly affected by rainfall δD value, the litter water δD value were depleted at first and then enriched. The δD value of spring and groundwater were not affected by short-term rainfall, so they could supply water for plant in the dry season. ©, 2015, Chinese Academy of Forestry. All right reserved.


Sun S.,Chinese Academy of Forestry | Meng P.,Chinese Academy of Forestry | Zhang J.,Chinese Academy of Forestry | Jia C.,Dagou he National Forest Farm | Ren Y.,Dagou he National Forest Farm
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2012

Trees, especially big ones, have huge and complicated vascular systems which make the long-distance water transport difficult to study. We used the heat dissipation method and deuterated water as tracers to characterize water transport and storage properties of Quercus variabilis trees under the different water stress treatment. The transit time for D2O transport from the trunk base to the upper branches and the tracer residence time were determined by measuring hydrogen isotope ratios in water extracted from branches sampled in regular intervals. The result indicated that the maxima δD of full irrigation (FI), mild water stress (LWS) and severe water stress (SWS) respectively increased to 586. 67‰997. 33‰and 1364. 89‰after injecting deuterium tracer. There were significant differences in maxima δD among the three treatments. The tracer velocities with LWS and SWS were significantly lower than FI treatment but the tracer half-life and residence time were longer than FI treatment. The branch PLC, sap flow rate, water potential and transpiration rate were also observed. The branch PLC treated with LWS and SWS was significantly higher than FI treatment and the sap flow rate, water potential and transpiration rate were lower. There significantly positive correlations between tracer velocity and leaf transpiration rate (P<0. 01,n =27), and between tracer velocity and sap flow rate (P<0. 01,n =9). The results indicated that water transport was determined by transpiration rate. The PLC and branch water potential were inversely correlated with tracer velocity (P<0. 01,n = 27), suggesting that drought stress-induced embolism and lower water potential should increase resistance to water transport. Tracer half-life and residence time increased as water stress increased. Tracer half-life and residence time were significant exponential functions with the branch PLC (P<0. 01,n =27), but power functions with the leaf transpiration rate. The times needed for transporting the same volume tracer were increased, indicating that water transport efficiencies were reduced because of PLC, transpiration and storage water variations under water-stress condition. Analyses of sap flow showed that the calculative fluxes of drought treatments within tracer half-life and residence time were significantly higher than FI treatment. The amounts of water carrying the same volume tracer were increased as stress degree increased. The results indicated that the increased water was possibly stored in the sapwood and re-exchanged to transpiration stream when transpiration was strong in the daytime. Quercus variabilis trees should reduce the water transport velocity and efficiency to adapt water stress environment by xylem embolism and storage-water exchange.


Chen P.,Chinese Academy of Forestry | Zhang J.,Chinese Academy of Forestry | Meng P.,Chinese Academy of Forestry | Jia C.R.,Dagou he National Forest Farm | And 2 more authors.
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2014

Stable carbon isotope composition (б13 C value) was one of the effective methods for measuring the plant water use efficiency (WUE),and was already applied in many plants. At present, the study on estimation of the WUE of Cassia obtusifolia L.. by б13 C was a few. In order to prove the reliability of б13 C on measuring WUE for Cassia obtusifolia L., б13 C、 stable carbon isotope discrimination (Δ13 C) 、WUE and the relationship among them are measured in different organs (root, steam, leaf) and different growth stages by pot experiment and б13 C. The results showed that, the б13 C value and Δ13 C of roots were highest, the next were stems, leaves were minimum, there were significant level in the б13 C value and б13 C in roots in different growth stages, positive relationship were found between the Δ13C value and WUE in stems and leaves, negative relationship were found between the Δ13C and WUE in stems and leaves. It showed significant positive correlation level among WUE (Potted method) and WUEL、WUES、WUER (Carbon isotope method), related coefficient were 0. 86、 0. 82、0.80 respectively, those showed carbon isotope technology was reliable to determine the WUE of Cassia obtusifolia L. © 2014 Science Press. All rights reserved.


Sun S.J.,Chinese Academy of Forestry | Meng P.,Chinese Academy of Forestry | Zhang J.S.,Chinese Academy of Forestry | Jia C.R.,Dagou he National Forest Farm | Ren Y.F.,Dagou he National Forest Farm
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2014

This study analyzed the hydrogen and oxygen isotope characteristics of waters from rain, spring, ground and soil, and xylem water of Quercus variabilis and Grewia biloba in the southern lithoid hilly area of the Taihang Mountains, China. Water use patterns of Q. variabilis and G. biloba were determined with the IsoSource model and leaf transpiration strategyof the two species was analyzed. The results indicated significant difference between δ18O and δ D values of the xylem water of the two species in the same ecosystem. Q.variabilis and G. biloba mainly used shallow water from 0—20 cm soil layer during the wet season, while both species uptook deep soil water during the dry season. In the dry season, Q.variabilis mainly used water from 40—60 cm soil layer, while G. biloba mainly used water from 20—40 cm soil layer. Other than that, Q.variabilis used more spring water than G. biloba, accounting for 19.6% of its total water usage during the dry season. So, Q.variabilis and G. biloba could avoid water competition due to the different water sources for the two species in the dry season. Q. variabilis, which occupied the upper canopy layer in the ecosystem, showed midday depression of transpiration that was caused by partially closed stomata at noon during the dry season. Meanwhile, the transpiration rate and stomatal conductance of shaded G. biloba were 46.94% and 30.58% lower than that of Q. variabilis, respectively. With different strategies, Q.variabilis by using deep soil water and partially closed stomata, and G. biloba by using shallow soil water and decreasing transpiration, the two species used the limited water sources reasonably during the dry season, as the result the ecosystem composed of these two species showed strong ecological adaptability to the fragile environment in the southern lithoid hilly area of the Taihang Mountains. © 2014, Science Press. All rights reserved.

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