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Sap Flow Flux Of Main Forest Types In Eastern Region Of Northeastern China

Posted on:2007-01-19Degree:DoctorType:Dissertation
Country:ChinaCandidate:L SunFull Text:PDF
GTID:1103360185955626Subject:Ecology
Abstract/Summary:PDF Full Text Request
This paper studied on the sap flux density of main tree species in typical forest types in eastern region of northeastern China by using Granier technic. 49 dominant trees, medium trees and suppressed trees separately in artificial korean pine forest, secondary birch forest, natural hard and broadleaved forest (it has no suppressed Juglans mandshurica sample trees and only two dominant and medium Fraxinus mandshurica sample trees) , secondary trembling aspen forest and mongolian oak forest were selected and measured sap flux density. At the same time various environmental factors including air temperatrure, relative humidity, soil temperature, soil moisture, photosynthesis effective radiation and wind speed etc were monitored at intervals of 15min from 5.29 to 10.29 in the whole growing season, we get nearly 5 millions of data. On the basis of these monitoring data, the characters of sap flux density of main tree species including changing rule during day and night, under different weather conditions and different time in growing seasons were studied. The characters of sap flux of different tree species in different diameter calss were brought out. The relations between sap flux and environmental factors were analyzed by using continuous sap flux and environmental factors data. The leading factors which influence the changing of sap flux of different tree species and the responsing rules of sap flux from environmental factors in different seasons were illustrated. The correlation equations between sapwood and diameter at breast height were built by drilling growth ring and getting width of sapwood in sample plots. The sapwood areas of different forest types and canopy transpiration data were estimated.The curves of sap flow density of Pinus koraiensis, Betula platyphylla, Popidus davidiana, Quercus mongolica, Juglans mandshurica, Fraxinus mandshurica etc 6 tree species is mono-peak and has significant diurnal change patterns during clear sky days, their difference is from the duration of peak value. There is weak sap flow fluctuation during final stage of growing season, Betula platyphylla and Popidus davidiana has bigger fluctuation than other tree species. Sap flow density is low and anomalistic, even formed multi-peak curves which has not obvious peak value during rainy days, sap flux density during night is larger than its in sunny days. Popidus davidiana has larger unregular peak value than others during rainy days. The fluctuations of sap flow of Populus davidiana and Quercus mongolica are bigger than others, Pinus koraiensis' fluctuations is smallest.The character of sap flux for dominant, medium and suppressed sample tree in different forest types: peak value of sap flow density for Pinus koraiensis dominant trees is larger than medium, medium's peak value is larger than suppressed sample tree and the difference is obvious. The peak value of dominant's sapflow is obviously larger than medium andsuppressed sample tree, but between medium and suppressed sample trees is closely for Betula platyphylla and Populus davidiana. For Juglans mandshurica sap flow density of medium tree is larger than dominant tree, the curve shape of sap flow of medium tree is nearly trapezium, the curve shape of sap flow of dominant tree is semicircle because of influence of tree age. For Fraxinus mandshurica, its sap flow density is similar to Juglans mandshurica. For Quercus mongolica, sap flow density of dominant tree is obvious larger medium and surppressed trees.Average monthly sap flow density is less and less with the moving of growing season, the sap flow density is weakly fluctuation during last time in growing season(october). The maxium average monthly sap flow density for varied tree species appears from June to august, the difference between dominant, medium and suppressed sample trees for varied tree species is large.Maxium daily sap flux was 2018.7 (dominant tree in June) ,2623.97 (dominant tree inJune) , 2170.26 (medium tree in June) , 2260.91 (medium tree in June) , 2229.29(dominant tree in July) , 3881.17 (dominant tree in June) L.m~2.d~l for Pinus koraiensis,Betula platyphylla, Juglans mandshurica, Fraxinus mandshurica, Quercus mongolica andPopulus davidiana respectively.We get the main influence factors on dominant, medium and suppressed trees byanalyzing all environmental factors. It is vapor deficit pressure(VPD), photosynthesis effective radiation (PAR) , temperature(Ta) and wind speed out of forest(W ?h) for dominant tree , photosynthesis effective radiation (PAR) , vapor deficit pressure(VPD), soil moisture in 25cm(MS25) and soil moisture in 35cm(MS35) for medium tree, vapor deficit pressure(VPD), rain(RAIN)> wind speed in forest (W a) and soil moisture in 35cm(MS35) for suppressed tree. The relation between sapwood and diameter at breast height is in the following order: Betula platyphylla ( R2=0.986 ) > Pinus koraiensis ( R2=0.82 ) > Fraxinus mandshurica (R2=0.786) > Juglans mandshurica ( R2=0.763 ) > Populus davidiana ( R2=0.68 ) > Quercus mongolica (R2=0.63) Daily transpiration rate was 4^ 32.3K 3.36> 11.51 and 4.82t.hm"2.d"'and quantity water use of canopy level was 681.^ 4911.28, 503.39> 1725.85 and 723.56t.hm~2 for artificial korean pine forest , secondary birch forest, natural hard and broadleaved forest, secondary trembling aspen forest and natural mongolian oak forest respectively.
Keywords/Search Tags:Sap flow density, Sap wood, Environmental factors, Thermal dissipation method
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