Landform effects on tree size in reestablished forests after fires

The spatial heterogeneity of tree size in stands recovered after fires was examined in a 5m×110m belt transect and 150 plots in the Teshio Experiment Forest situated in northern Japan. Tree growth in the reestablished stands was affected by topographic conditions. Canopy height and maximum DBH varied with slope aspect, topographic position, and elevation as well as stand age. They were found to be small 1) on southeast-, south-, southwest-, and west-facing slopes, 2) on ridges, upper parts of slopes, and terrace surfaces, and 3) within high-elevation zones. The effects of ultramafic soil from serpentinized rock on tree size were smaller than those of the topographic conditions. It follows from these findings on reestablished communities that prevailing southwesterly winds are importantly involved in regeneration

Growth and Photosynthetic Performance of Seedlings of Two Larch Species Grown in Shaded Conditions

Article

Relationship between the riverine nitrate-nitrogen concentration and the land use in the Teshio River watershed, North Japan

The present research investigated the relationship between nitrate-nitrogen (NO3-N) in river water and the land use/land cover (hereafter, land use) in the Teshio River watershed located in northern Hokkaido island to understand the effect of human activities such as agriculture, forestry, industry, and urbanization in the drainage basin on the river ecosystem quality and services. River water was sampled at nine points seasonally during a two-year period and the nutrients concentration was measured. Land use profiles were estimated at two spatial scales-riparian and sub-catchment for each sampling station. The spatial pattern of water quality in the Teshio River showed increased NO3-N levels associated with agriculture and urban expansion, and forest reduction in the watershed. Land use at the riparian scale closely reflected that at the sub-catchment scale, which masked the unique riparian buffer effect on the river water condition. The high agricultural and reduced forest area in the riparian zone, especially in the upper middle reach, could be a possible reason for a decline of ecosystem service for the provisioning of clean water and habitat for aquatic organisms. Measures towards sustainable and more nature-friendly agricultural management are necessary in the area to protect the Teshio River ecosystem and its ecosystem services

Micro-Environmental Analysis of the Natural Regeneration of Larch Forests in Northern Japan

Research Material

Plant Biomass and Productivity of Larix gmelinii Forest Ecosystems in Northeast China：Intra- and Inter- species Comparison

Article

Roles of dominant understorySasabamboo in carbon and nitrogen dynamics following canopy tree removal in a cool-temperate forest in northern Japan

To clarify the role of dense understory vegetation in the stand structure, and in carbon (C) and nitrogen (N) dynamics of forest ecosystems with various conditions of overstory trees, we: (i) quantified the above- and below-ground biomasses of understory dwarf bamboo (Sasa senanensis) at the old canopy-gap area and the closed-canopy area and compared the stand-level biomasses of S. senanensis with that of overstory trees; (ii) determined the N leaching, soil respiration rates, fine-root dynamics, plant area index (PAI) of S. senanensis, and soil temperature and moisture at the tree-cut patches (cut) and the intact closed-canopy patches (control). The biomass of S. senanensis in the canopy-gap area was twice that at the closed-canopy area. It equated to 12% of total biomass above ground but 41% below ground in the stand. The concentrations of NO3− and NH4+ in the soil solution and soil respiration rates did not significantly change between cut and control plots, indicating that gap creation did not affect the C or N dynamics in the soil. Root-length density and PAI of S. senanensis were significantly greater at the cut plots, suggesting the promotion of S. senanensis growth following tree cutting. The levels of soil temperature and soil moisture were not changed following tree cutting. These results show that S. senanensis is a key component species in this cool-temperate forest ecosystem and plays significant roles in mitigating the loss of N and C from the soil following tree cutting by increasing its leaf and root biomass and stabilizing the soil environment