Karibu Fukuzawa's page
Research content
Elucidation of material cycle processes and environmental functions in forests
​
I am interested in the interaction between living organisms and the environment, and effects of the state of diverse forests, global environmental changes and human activities on carbon and nutrient cycling processes.
In particular, what we have been working on
-
Role of understory vegetation in forest carbon and nitrogen dynamics
-
Fine root dynamics in forests
-
Effects of disturbances such as deforestation on nutrient cycling
-
Effects of geological differences on stream water quality
-
Forest-village (where human is living) -sea connections, etc.
If you look down at your feet, here the ground is covered with dwarf bamboo grass (Sasa spp.).
Sasa grows abundantly as understory vegetation in the forests of Hokkaido, thus Sasa is an important research target in the forests.
​
Tree and undestory vegetation census, observation of the fine roots dynamics, and chemical analysis of samples such as plants, soil and water collected in fields in the lab etc. are conducted.
Half field, half chemical analysis.
Chemical analysis includes nitrogen/phosphorus, carbon, ionic components, metal components, etc.
It feels good to walk into the forest while listening to the chirping of birds, the sound of leaves blowing in the wind, and the sound of the stream.
Also, the task of extracting chemical data from samples in the lab is just as exciting as the science experiments in elementary school.
Specialty: Biogeochemistry, Forest Ecology
​
Introduction to some research projects
In order to investigate the effects of atmospheric nitrogen deposition on forest ecosystems, we are conducting long-term catchment-scale nitrogen fertilization and monitoring stream water quality. Since 2001, we have been fertilizing the entire catchment area of 1.4ha with ammonium nitrate (50kgN/ha per year). It has been found that the concentration of nitrate ions in strem water increases suddenly after 9 years from the start of fertilization. This forest is suggested to have a relatively high ability to retain nitrogen.
​Assuming feeding damage to understory vegetation by deer, we are investigating changes in soil nitrogen dynamcis by artificially removing bamboo grass. It has been found that the short-term impact on soil nitrogen cycling is small. It was also found that the ratio of the above-ground part to the below-ground part of Sasa is almost 1:1, and even if the above-ground part is cut, the fine roots of the below-ground part are maintained. To verify the effect of this experiment, it is necessary to investigate over a longer period of time, and investigations are still ongoing.
We are investigating the impact of forestry operations such as deforestation on strema water quality by conducting forestry operations at the catchment scale.
Long-term monitoring of river water quality is being carried out as a basic research subject for research forests.
​
We also conduct joint research with external researchers.
​
​
​ From the paper
Yanagawa S, Fukuzawa K, Takagi K, Shibata H, Satoh F (2023) Presence of understory dwarf bamboo determines ecosystem fine root production in a cool-temperate forest in northern Japan. Journal of Forest Research (in press) https://www.tandfonline.com/doi/full/10.1080/13416979.2023.2169981
Evaluating fine root production is labor intensive and difficult, so attempts are being made to estimate it from above-ground tree mass. We quantified the production of fine roots separately for trees and bamboo grass in multiple forest stands where Sasa senanensis (hereafter, Sasa) grows in northern Hokkaido., and whether it is possible to predict from the amount of trees in the above-ground part. Although the fine root production of trees increased with the above-ground tree mass, the overall fine root production decreased with the above-ground tree mass. This trend was similar to that of Sasa fine root production. Even in areas where trees do not grow, it has a fine root biomass equivalent to that of a forest with dense trees. These results suggest that whether Sasa grows or not determines the total fine root production.Therefore, in cool-temperate forests where Sasa grows densely on the forest floor, it is difficult to predict fine root production from above-ground tree mass, and it was found that fine root dynamics cannot be discussed without considering undesstory vegetation.
​
In order to investigate the effects of reduced snow cover on fine root dynamics in eastern Hokkaido, we separately investigated the temporal patterns of fine root production and mortality of oak trees (Quercus crippula) and Sasa nipponica (Sasa). In the snow removal area, the timing of the whole fine root production has been advanced. In addition, in terms of plant species, while Sasa was faster, oak was not. In addition, the production of fine roots increased only in Sasa. On the other hand, no effect of snow removal treatment on fine root death (including decomposition) was observed. It was suggested that the decrease in snow cover would work in favor of Sasa through earlier snowmelt, and that the competitive relationship between Sasa and oak would change.
​
Paper publication informationherePlease refer to the.
Visits to the research forest (laboratory) are accepted at any time. Please feel free to contact us!
​
Link
​