Wood Core Samples Research Articles

Decomposition rate constants of Picea abies logs in southeastern Norway

Decomposition rate constants were estimated from 384 cross sections of Norway spruce (Picea abies (L.) Karst.) logs with base diameter >7.0 cm collected in open areas at five different study sites in southeastern Norway. Fresh wood core samples were taken from 95 standing trees adjacent to the logs to estimate the initial density of these cross sections. Based on this chronosequence, a simple negative exponential function of time showed an average decomposition rate constant for all cross sections of 0.033 per year. Cross-section diameter, ground contact, soil moisture, and aspect were all found to have significant impacts on the decomposition rate constant. For different combinations of these characteristics the decomposition rate constant ranged from a minimum of 0.0165 per year to a maximum of 0.0488 per year.

Decomposition rate constants of <i>Picea abies</i> logs in southeastern Norway

Decomposition rate constants were estimated from 384 cross sections of Norway spruce (Picea abies (L.) Karst.) logs with base diameter >7.0 cm collected in open areas at five different study sites in southeastern Norway. Fresh wood core samples were taken from 95 standing trees adjacent to the logs to estimate the initial density of these cross sections. Based on this chronosequence, a simple negative exponential function of time showed an average decomposition rate constant for all cross sections of 0.033 per year. Cross-section diameter, ground contact, soil moisture, and aspect were all found to have significant impacts on the decomposition rate constant. For different combinations of these characteristics the decomposition rate constant ranged from a minimum of 0.0165 per year to a maximum of 0.0488 per year.

Temporal and spatial variations in dielectric constant and water status of dominant forest species from New England

Temporal and spatial characteristics of microwave dielectric properties and water status of several forest species were investigated during the 1990 and 1991 growing seasons as part of the NASA FED MAC. Data presented were acquired from, Durham, New Hampshire (white pine, eastern hemlock, and American beech), and Howland, Maine (eastern hemlock and red spruce). Dielectric properties of trunk wood were measured using C-band, L-band, and P-band dielectric probes. For the Durham specimens, electrical resistance was measured using a digital ohmmeter. Water status of the trees studied was determined either by use of a Scholander pressure bomb on branch samples or by fresh weight/dry weight assessment of wood core samples. Results indicate the following: 1) Radial dielectric profiles matched the regions of the functional sapwood such that the sapwood was characterized by a higher dielectric than the bark and heartwood tissues. 2) A hysteresis exists between diurnal variations in branch water potential and trunk sapwood dielectric. 3) The dielectric properties were positively correlated with wood core moisture content, while the electrical resistance was poorly correlated with moisture content. 4) Using categories of electrical resistance measurements as a qualitative assessment of relative ion concentrations, the dielectric measurements were not sensitive to the different ion concentrations within the xylem and phloem exudate. These results support the view that dielectric properties are strongly correlated with moisture status in trunk wood and that diurnal variations in dielectric are related to diurnal fluctuations in water potential. The lag between changes in branch water potential and trunk dielectric varies, depending on the structure, evaporative demand, and water storage capacity of the sapwood.

Production of pig iron in 1912

Temporal and spatial characteristics of microwave dielectric properties and water status of several forest species were investigated during the 1990 and 1991 growing seasons as part of the NASA FED MAC. Data presented were acquired from, Durham, New Hampshire (white pine, eastern hemlock, and American beech), and Howland, Maine (eastern hemlock and red spruce). Dielectric properties of trunk wood were measured using C-band, L-band, and P-band dielectric probes. For the Durham specimens, electrical resistance was measured using a digital ohmmeter. Water status of the trees studied was determined either by use of a Scholander pressure bomb on branch samples or by fresh weight/dry weight assessment of wood core samples. Results indicate the following: 1) Radial dielectric profiles matched the regions of the functional sapwood such that the sapwood was characterized by a higher dielectric than the bark and heartwood tissues. 2) A hysteresis exists between diurnal variations in branch water potential and trunk sapwood dielectric. 3) The dielectric properties were positively correlated with wood core moisture content, while the electrical resistance was poorly correlated with moisture content. 4) Using categories of electrical resistance measurements as a qualitative assessment of relative ion concentrations, the dielectric measurements were not sensitive to the different ion concentrations within the xylem and phloem exudate. These results support the view that dielectric properties are strongly correlated with moisture status in trunk wood and that diurnal variations in dielectric are related to diurnal fluctuations in water potential. The lag between changes in branch water potential and trunk dielectric varies, depending on the structure, evaporative demand, and water storage capacity of the sapwood.