The sap flow method is widely used to estimate forest transpiration.However,at the individual tree level it has spatiotemporal variations due to the impacts of environmental conditions and spatial relationships among ...The sap flow method is widely used to estimate forest transpiration.However,at the individual tree level it has spatiotemporal variations due to the impacts of environmental conditions and spatial relationships among trees.Therefore,an in-depth understanding of the coupling effects of these factors is important for designing sap flow measurement methods and performing accurate assessments of stand scale transpiration.This study is based on observations of sap flux density(SF_(d))of nine sample trees with different Hegyi’s competition indices(HCIs),soil moisture,and meteorological conditions in a pure plantation of Larix gmelinii var.principis-rupprechtii during the 2021 growing season(May to September).A multifactorial model of sap flow was developed and possible errors in the stand scale sap flow estimates associated with sample sizes were determined using model-based predictions of sap flow.Temporal variations are controlled by vapour pressure deficit(VPD),solar radiation(R),and soil moisture,and these relationships can be described by polynomial or saturated exponential functions.Spatial(individual)differences were influenced by the HCI,as shown by the decaying power function.A simple SF_(d)model at the individual tree level was developed to describe the synergistic influences of VPD,R,soil moisture,and HCI.The coefficient of variations(CV)of the sap flow estimates gradually stabilized when the sample size was>10;at least six sample trees were needed if the CV was within 10%.This study improves understanding of the mechanisms of spatiotemporal variations in sap flow at the individual tree level and provides a new methodology for determining the optimal sample size for sap flow measurements.展开更多
The fossil shells on the sedimentary rocks were collected from The Historical Park,Ban Sap Noi Geopark,Phetchabun Province,Thailand.However,the fossils remained in this area were investigated on the characteristic spe...The fossil shells on the sedimentary rocks were collected from The Historical Park,Ban Sap Noi Geopark,Phetchabun Province,Thailand.However,the fossils remained in this area were investigated on the characteristic species only in geological studies with taxonomy for fossil age predicting.To fill up the gap of these studies,the material characterization techniques were used to study the chemical composition and structure of fossil shells I,II and III.The results clearly showed that the morphologies of all fossil shells were Brachiopod fossils with different species.The functional group and elemental composition of all fossil shells showed that the high content of calcium carbonate was a major composition.In addition,the high content of quartz indicated the silica precipitation phenomenon in all fossil shells.The element composition of cross-sectional morphology and energy dispersive spectroscope (EDS mapping) were used to confirm the presence of Si element in each zone of fossil shells.The crystal structures of all fossil shells were investigated and indicated that the calcium carbonate compound was a calcite phase and silicon dioxide compound was a quartz phase.Moreover,the crystal structure of quartz phase was used to calculate the crystallinity index.The crystallinity index values in all fossil shells indicated a well-crystallized quartz.The age of fossil shells was estimated and found to be brachiopod fossil in carboniferous period with the age of about 359.2 to 299.0 million years.展开更多
基金supported by the Fundamental Research Funds of the Chinese Academy of Forestry(CAFYBB2020QB004)the National Natural Science Foundation of China(41971038,32171559,U20A2085,and U21A2005).
文摘The sap flow method is widely used to estimate forest transpiration.However,at the individual tree level it has spatiotemporal variations due to the impacts of environmental conditions and spatial relationships among trees.Therefore,an in-depth understanding of the coupling effects of these factors is important for designing sap flow measurement methods and performing accurate assessments of stand scale transpiration.This study is based on observations of sap flux density(SF_(d))of nine sample trees with different Hegyi’s competition indices(HCIs),soil moisture,and meteorological conditions in a pure plantation of Larix gmelinii var.principis-rupprechtii during the 2021 growing season(May to September).A multifactorial model of sap flow was developed and possible errors in the stand scale sap flow estimates associated with sample sizes were determined using model-based predictions of sap flow.Temporal variations are controlled by vapour pressure deficit(VPD),solar radiation(R),and soil moisture,and these relationships can be described by polynomial or saturated exponential functions.Spatial(individual)differences were influenced by the HCI,as shown by the decaying power function.A simple SF_(d)model at the individual tree level was developed to describe the synergistic influences of VPD,R,soil moisture,and HCI.The coefficient of variations(CV)of the sap flow estimates gradually stabilized when the sample size was>10;at least six sample trees were needed if the CV was within 10%.This study improves understanding of the mechanisms of spatiotemporal variations in sap flow at the individual tree level and provides a new methodology for determining the optimal sample size for sap flow measurements.
基金supported by the Science Achievement Scholarship of Thailand (SAST)the support of Office of Atom for Peace,Thailand and Thailand Institute of Nuclear Technology (a public organization) for providing facilities for some experiment in this work。
文摘The fossil shells on the sedimentary rocks were collected from The Historical Park,Ban Sap Noi Geopark,Phetchabun Province,Thailand.However,the fossils remained in this area were investigated on the characteristic species only in geological studies with taxonomy for fossil age predicting.To fill up the gap of these studies,the material characterization techniques were used to study the chemical composition and structure of fossil shells I,II and III.The results clearly showed that the morphologies of all fossil shells were Brachiopod fossils with different species.The functional group and elemental composition of all fossil shells showed that the high content of calcium carbonate was a major composition.In addition,the high content of quartz indicated the silica precipitation phenomenon in all fossil shells.The element composition of cross-sectional morphology and energy dispersive spectroscope (EDS mapping) were used to confirm the presence of Si element in each zone of fossil shells.The crystal structures of all fossil shells were investigated and indicated that the calcium carbonate compound was a calcite phase and silicon dioxide compound was a quartz phase.Moreover,the crystal structure of quartz phase was used to calculate the crystallinity index.The crystallinity index values in all fossil shells indicated a well-crystallized quartz.The age of fossil shells was estimated and found to be brachiopod fossil in carboniferous period with the age of about 359.2 to 299.0 million years.
