TITLE:
Relevance of Carbon Sequestration to the Physiological and Morphological Traits of Several Green Roof Plants during the First Year after Construction
AUTHORS:
Takanori Kuronuma, Hitoshi Watanabe
KEYWORDS:
Growth Analysis, Inducible Type of CAM, Ophiopogon japonicus, Sedum mexicanum, Zoysia matrella
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.8 No.1,
December
31,
2016
ABSTRACT: Different vegetation types used for the extensive green roofs have characteristic
physiological and morphological traits (e.g., C3, C4, or CAM photosynthesis,
deciduous or evergreen). Several Sedum species are recognized as “inducible
CAM” type plants. These differences in the physiological and morphological
traits have a considerable effect on the carbon sequestration in the green
roofs. The objective of the present study was to quantify the carbon sequestration
in several green roof plants during the first year after the construction of
the green roofs and to clarify the relevance of the physiological and morphological
traits to each plant’s ability to sequester carbon in its body using the
growth analysis method. We used Zoysia matrella , Ophiopogon japonicus ,
and Sedum mexicanum species for the study wherein, S. mexicanum was assigned
to the wet, dry, and non-irrigation treatments, and Z. matrella and O.
japonicus only received the wet treatment. During the first year after the construction,
carbon sequestration in the plants and the substrate of S. mexicanum was in the range of 276 to 364 g-C/m2/year, which was similar to that of O. japonicus and the finding of a previous study. In contrast, Z. matrella exhibited
the highest carbon sequestration (670 g-C/m2/year), which is also expressed
as the relative plant C-sequestration rate per whole-plant C-content
(RGRc), because Z. matrella is a C4 plant and exhibits the highest net assimilation
rate (NARc) of all species. Significant differences were not observed in
RGRc , NARc , and RMF (root mass fraction) in S. mexicanum between the wet
and dry treatments. These results suggest that in countries with high rainfall, a
high frequency of irrigation has an insignificant effect on the physiological
and morphological characteristics, and carbon sequestration in the Sedum green roofs.