Physiological Plant Ecology

• Japanese

Physiological　Plant　Ecology

Ecological analysis of stand dynamics in forests ecophysiological of water use mechanism in woody species

Staff

Assoc. Prof. Dr. MIKI Naoko 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

• Miki NH, Sasaki S, Yang L, Ogasa MY (2017) Effects of soil nutrient conditions on water transport properties and recovery from severe drought stress in Pinus densiflora saplings. Journal of Forest Research, DOI: 10.1080/13416979.2017.1320207
• Miki NH, Kubori F, Yang L, Matsuo N, Zhang G, Wang L, Yoshikawa K (2016) Effective water use and growth of a prostrate lifeform shrub, Juniperus sabina, in semiarid areas of China. Journal of Arid Land Studies, 26(3): 95-99.
• Murakami Y, Miki NH, Yang L, Zhang G, Wang LH, Yoshikawa K (2016) Water transport properties of seven woody species　from the semi-arid Mu Us Sandy Land, China. Landscape and Ecological Engineering, 12: 209-220.
• Uyanga A, Hamano K, Makimoto T, Kinoshita S, Akaji Y, Miyazaki Y, Hirobe M, Sakamoto K (2016) Temporal and spacial dynamics of an old-growth beech forest in southwestern Japan. Journal of Forest Research, 21: 73-83.
• Ogasa M, Miki NH, Okamoto M, Yamanaka N, Yoshikawa K (2014) Water loss regulation to soil drought associated with xylem vulnerability to cavitation in temperate ring-porous and diffuse-porous tree seedlings. Trees, 28: 461-469.
• Otoda T, Doi T, Sakamoto K, Hirobe M, Baatarbileg N, Yoshikawa K (2013) Frequent fires may alter the future composition of the boreal forest in northern Mongolia. Journal of Forest Research, 18: 246-255.
• Otoda T, Sakamoto K, Hirobe M, Undarmaa J, 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. Journal of Forest Research, 18: 82–92.
• Ogasa M, Miki NH, Murakami Y, Yoshikawa K (2013) Recovery performance in xylem hydraulic conductivity is correlated with cavitation resistance for temperate deciduous tree species. Tree Physiology, 33: 335-344.
• Sakamoto K (2010) Conservation of secondary forests for biodiversity and sustainable bio-resource management in Japan. Proceedings of the 2010 International Conference on Community Forestry, 11-16.