Dissertation > Agricultural Sciences > Forestry > Forest tree species > Coniferous > Larch

Transpiration Characteristic of Dahurian Larch Trees Transplanted from a Latitudinal Gradient

Author ZhangYanQun
Tutor WangChuanKuan
School Northeast Forestry University
Course Ecology
Keywords Larix gmelinii Transpiration rate Flow flux Water use efficiency Scale conversion
CLC S791.22
Type Master's thesis
Year 2008
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The boreal forest is located in a sensitive climate change in high latitudes, understanding of the spatial and temporal dynamics of water consumption by transpiration process and its control factor is the basis of the evaluation and prediction of the role of forests in the climate system. Xing'an larch (Larix gmeliniiRupr.) Dominant tree species in the forests of northern China, study the water physiological variation, have important practical value for the evaluation and prediction of this important species distribution patterns and functional process dynamics under climate change conditions and theoretical significance. In this study, four latitudes (the Daxinganling Tahe TH, the Daxinganling Songling SL, the Heihe Sunwu SW, Yichun Dailing DL) Xing'an larch plantation ecosystem (trees Litters soil layer A and B layers ) transplanted to the southern edge of its distribution area constitutes the four experimental treatments, in order to explore the spatial and temporal changes in the pattern of trees on Transpiration Characteristics and its influencing factors. 5-year-old experimental trees transplanted measured 9 students carried their water consumption by transpiration factor parameters the same period in the two scales coniferous and individual determination and analysis found that transplanting L. gmelinii transpiration from different latitudes Water consumption characteristics in coniferous and individuals scale there are significantly different. The coniferous scale the Larix gmelinii SL, SW, and DL transpiration rate (E) in the 0.47 ~ 8.31 mmol m -2 s -1 fluctuated between growing season an average of 3.11 mmol m -2 s -1 , close to the northern and temperate forest broadleaf E. The difference E treatment significantly, SL (3.95 mmol m -2 the s -1 )> DL (2.97 mmol m -2 s s -1 ); very significant difference between growing season in January and August (6.08 mmol m <> -1 ) ≈ SW (2.73 mmolm sup > -2 s -1 )> 9 (2.99 mmol m -2 s -1 )> 7 months (1.65 mmol m -2 s -1 ) ≈ June (1.50 mmol m -2 s -1 ). Fluctuations in the growing season E comes from the determination of the the period air vapor pressure deficit (VPD), soil volumetric water content (VWC), environmental factors, and specific leaf area (SLA), stomatal conductance degree (g s ) morning sprig water potential and hydraulic conductance variation of physiological parameters, including environmental factors is the main cause of the monthly variations, while the biological factor is the source of the differences between the provenances. Individual scales, four processing units sapwood area flow flux (J s ) Daily Progress Usually a single peak curve is different because of the different stages of growth. The difference in the performance of different growth stages on the length of the peak level and duration. Fluctuations between the daily averages of four processing larch growing season J s 0.67-19.32 g cm -2 h -1 , with the North and temperate forest broadleaf species are similar. 4 of each stage of processing the J s daily mean different size relationship due on stage, but no significant difference between treatments, mainly caused by processing huge variability (coefficient of variation of up to 70%). Paired T-test showed that repeated treatments to different test day: the differences between the treatments significantly throughout the growing season J s average SL (11.19 g cm -2 h -1 ) ≈ DL (10.82g cm -2 h -1 )> TH (9.60g cm -2 h -1 )> SW (8.86 g cm -2 h -1 ). The difference between growing season, water consumption and the growth of the amount of processing and transplanting the latitude and body size, significant differences between the treatments, the descending order: SW ≈ DL> SL ≈ TH. Non-growing season, there is still liquid flow can be measured, but thermal equilibrium at low temperatures requires further study. Environmental factors affect J s and growth stage, the dominant influence factor PAR, VPD and the role played by Wind in a different stage of tree growth and experimental treatments ranging. With the increase of the time scale, the meteorological factors decisive role becomes small, sunny growing season J s was significantly related to the changes and VWC. , VWC will the impact J s and meteorological factors sensitivity correlation of the VWC low, J s and meteorological factors weakened. The two scale water use efficiency (WUE) differences in the pattern of differences in the processing. Blade scales, growing season WUE leaf differences between treatments are not significant, in decreasing order of SW (1.2pμmolCO 2 / mmolH 2 O ), DL (1.28μmolCO 2 / mmolH 2 O), SL (1.19μmolCO 2 / mmolH 2 O ), WUE leaf in the whole growing season fluctuations in the 0.24-1.89μmolCO 2 / mmolH 2 O between the change in June The lowest extreme drought, 7,9 month moderate drought in August in the middle. Individual scale to on (WUE) tree treatments a significant difference (P <0.001), with increasing latitude transplanting ground VCUE tree descending the four processing order DL> SW ≈ SL ≈ TH. The average WUE tree 2.403 g kg -1 . Leaves and individual scale comparative study found that: individual scale transpiration water consumption rate (J s ) start and peak lag the blade scales measuring value (E), the presence of water capacity of 9 students Xing'an larch crown night existence supplement the water content of the liquid flow. The trees leaves to the individual scale conversion process is complex, individual scale projections needles with long sticks top E conversion after spatial scales and time scales integrated water consumption is greater than the measured value. Not consider E variation within the canopy leaf measurement results directly applied to the canopy, the kind of the representative branches selected external push results enormous impact. The results of this study, the long-term climate the domestication will affect Larch water physiological characteristics, climate warming may indirectly affect water consumption per plant, significantly improve growth by accelerating the trees, the water consumption rate and water use efficiency can also occur significant change, but the degree of change in soil moisture conditions significantly affect future climate prediction model, which should be given full consideration.

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