Relationships between vegetation change and geomorphic conditions in suburban forests of Japan: Analysis by means of digital aerial photogrammetry and geographical information systems

金沢大学人間社会研究域人間科学系The relationships between successional vegetation change and geomorphic conditions were analyzed by using a high-resolution digital terrain model (DTM) and a time series of converted digital vegetation maps combined within a geographical information system (GIS). The results of the analysis confirmed that the pattern of vegetation change is a function of geomorphic conditions (measured in terms of spatio-statistical values of various parameters and time series of those values). Current geoecological studies are usually carried out by means of detailed field observations with high spatial resolution, and the results of our study suggest that a GIS can easily deal with such data over a large area and long time period. In the study area, unforested s ites were reforested using Japanese red pine (Pinus densiflora) as part of the forest rehabilitation work that occurred in the early 1950s. After that, two main patterns of vegetation change from pine forest to deciduous broadleaved forest occurred. In one type, the deciduous broadleaved forest reappeared quickly. In the other, the pine forests remained for a long time. Stands that underwent relatively rapid succession were found on north-facing gentle slopes close to large bodies of water. Stands that did not undergo rapid succession were found on steeper, warmer, and drier slopes (often south-facing slopes farther from bodies of water). The rate of forest succession towards deciduous broadleaved forest is a function of these geomorphic conditions. This suggests that forest succession is influenced by intermediate factors controlling by geomorphic conditions of site, such as soil moisture and soil thickness

Molecular dynamics simulation of water droplet in contact with platinum surface

A water droplet in contact with a platinum surface was simulated by the molecular dynamics method. Water molecules were modeled with the well-known SPC/E model and the platinum surface was represented by three layers of harmonic molecules with the constant temperature heat bath model using the phantom molecules. Two types of water-platinum pair potential functions based on extended Hückel calculations were employed, one was developed by Spohr and Heinzinger in 1988 and the other was proposed by Zhu and Philpott in 1994. In the spreading process of a liquid droplet on a platinum surface, the area of contact region between water and platinum expanded just in proportional to the one-third power of time. This spreading rate was clearly in contrast to the case of Lennard-Jones droplet. Even though the water droplet finally spread to a monolayer film on fcc (111) surface with S-H potential, a stable droplet structure on a monolayer film was realized with Z-P potential. The mechanism of the ‘drop on film ’ structure was explained by the very concentrated monolayer film of water. Comparing three different platinum surface structures, (111), (100) and (110), contact angle varied drastic and it was largest on fcc (100) surface. 1

TED-AJ03-183 A MOLECULAR DYNAMICS SIMULATION OF WATER DROPLET IN CONTACT WITH A PLATINUM SURFACE

A water droplet in contact with a platinum surface was simulated by the molecular dynamics method. Water molecules were modeled with the well-known SPC/E model and the platinum surface was represented by three layers of harmonic molecules. The phantom molecules were used beneath the layers of platinum surface in order to mimic the constant temperature heat bath. As the potential function between water and platinum surface, two different models developed by Spohr & Heinzinger (1988) and Zhu & Philpott (1994) were employed. These potential models were derived from the extended Hükel calculations between a water molecule and a platinum cluster. As the initial condition, a water droplet with the density of liquid water at 350 K was placed on the center of the platinum surface. For the initial 100 ps, velocit