Plant species in extreme habitat condition will exhibit physiological responses to the condition. To examine the responses and their seasonal change in different microhabitats, we studied photosynthesis properties of Miscanthus condensatus (a non-N-fixing C4 pioneer grass) growing on a volcanically devastated site.
Methods
Our study was conducted on a Miyake-jima volcanically devastated site (formed by 2000-year eruption) between 2017 and 2018. We determined leaf N, photosynthetic capacity, and photosynthetic N use efficiency (PNUE) in three contrasting microhabitats (bare land, shrub land gap, and shrub land under canopy) at 1-month intervals from July to October 2017, and from May to June 2018.
Result and discussion
There were no significant differences in PNUE among three sites. However, the PNUE values in BL were higher than those in the other two habitats in June and October. Considering the rainfall data before our measurements, the higher PNUE in BL appears to be caused by higher rainfall. This suggest that M. condensatus on BL, the most devastated site, can achieve high PNUE, however it is dependent on the water availability. We considered that due to high PNUE value, M. condensatus can be adaptive to the extremely low soil N conditions in Miyake-jima volcanically devastated area.