Physiological　Plant　Ecology

Ecological analysis of forest maintenance mechanism and physiological analysis of water use and matter production by tree species

Staff

	Prof. Dr. Keiji SAKAMOTO E-mail：skmtelm＠（@okayama-u.ac.jp） Applied plant ecology
	Assoc. Prof. Dr. Naoko MIKI E-mail：miki＠（@okayama-u.ac.jp） Plant physiological ecology

Research Subjects

The stand structure and dynamics of forests are researched to demonstrate the mechanism of regeneration in forests. The eco-physiological characteristics of invasion, establishment, survival, and growth in relationship to whole-plant water use and matter production of tree species are analyzed to determine the strategies of different species. Based on these research results, an optimal model in the management of forests is constructed for the sustainable conservation of the forests.

Analysis of forest dynamics

Recruitment and death in tree species have been repeated in forest communities, and we need to understand the dynamics for forest conservation. For this purpose, we analyze the ecological and eco-physiological characteristics of forest tree species in order to elucidate the survival strategies of tree species under different environments, the dynamics of forest communities, and the regeneration process. Target species are various forest trees growing in semi-arid regions and humid regions, and we me

Analysis of satoyama forests and development of conservation techniques for the forests

Satoyama forests, which were artificially maintained in Japan, have been abandoned and changed. The abandonment and changes have caused degradation of the forests from the aspects of biodiversity and environmental conservation. For reduction of the degradation in satoyama forests, it is necessary to clarify the processes of changes, and it is also necessary to restore and conserve satoyama forests. For the purpose, we analyze the ecological and eco-physiological characteristics of pine forests, deciduous forests, and bamboo forests in urban fringe areas. Based on the knowledge gained from these analyses, we intend to develop conservation techniques for those satoyama forests.

Study on water use characteristics in woody species

Plants lose more or less water from the leaves in the process of matter production. Therefore, it is essential to develop various characteristics such as suppression and rapid compensation for lost water for growth and survival. Based on the evaluation of various characteristics such as transpiration suppression, water transport, and water absorption, we are trying to clarify the water use characteristics and survival strategies on an individual organ level and a whole-plant level.

A study of the maintenance mechanism of water transport in woody species

Plants take CO2 from stomata on leaves for photosynthesis, and simultaneously lose H2O via stomata in the process of transpiration. Maintenance of the integrity of the root-to-leaf water transport pathway is essential for sustaining photosynthetic gas exchange and growth. The driving force of water transport is the water potential gradient between leaves and roots or soil, so a large water potential gradient is required. On the other hand, the gradient leads to an increase of the tension in the pathway and an increase of the risk of tension-induced xylem embolism (cavitation). Since the impact of this water flow inhibition give to trees mortality associated with drying is very large, it has been one of the most important factors that determine the survival and distribution of trees. As a target a variety of woody species in various regions, we are trying to clarify the maintenance mechanism of water transport function from the evaluation of response to hydraulic failure.

Publications

• Sakamoto, K., Miki, N., Tsuzuki, T., Nishimoto, T. and Yoshikawa, K. (2003) Comparison of stand dynamics after dieback caused by pine wilt disease among pine forests with different management regimes in western Japan. J. For. Res. 8, 303-309
• Miki, N., Otsuki, K., Sakamoto, K., Nishimoto, T. and Yoshikawa, K. (2003) Leaf water relations in Pinus densiflora Sieb. et Zucc. on different soil moisture conditions. J. For. Res. 8, 153-161
• Yang L., Miki N., Harada N., Hirobe M., Sakamoto K. and Yoshikawa K.(2008) Response of water-use properties and growth of Sabina vulgaris Ant. in different water conditions.Journal of Environmental Science for Sustainable Society. 2, 27-34
• Saroinsong, F.B., Sakamoto, K., Miki, N. and Yosikawa, K.（2006） Stand dynamics of a bamboo forest adjacent to a secondary deciduous broad-leaved forest. J. Jpn. Soc. Reveget. Tech. 32, 15-20
• Ogasa M., Miki N. and Yoshikawa K.(2010) Changes of hydraulicconductivity during dehydration and rehydration in Quercus serrata Thunb.and Betula platyphylla var. japonica Hara: the effect of xylem structures. Tree Physiol. 30:608-617.
• Ogasa, M., Miki, N. H., Murakami, Y. and Yoshikawa, K.(2013) Recovery performance in xylem hydraulic conductivity is correlated with cavitation resistance for temperate deciduous tree species. Tree Physiol. 33:335-344.
• Ishii, Y., Sakamoto, K., Yamanaka, N., Wang, L., and Yoshikawa, K. (2006) Light acclimation of needle pigment composition in Sabina vulgaris seedlings under nurse plant canopy. J. Arid Environ., 67, 403-415.
• Otoda T, Sakamoto K, Hirobe M, Undarmaa J and Yoshikawa K (2013) Influences of anthropogenic disturbances on the dynamics of white birch (Betula platyphylla) forests at the southern boundary of the Mongolian forest-steppe. J. For. Res. 18:82–92, 2013