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Variations in the foliar δ 13 C and C 3 /C 4 species richness in the Japanese flora of Poaceae among climates and habitat types under human activity
Author(s) -
Hanba Yuko T.,
Kobayashi Tsuyoshi,
Enomoto Takashi
Publication year - 2010
Publication title -
ecological research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.628
H-Index - 68
eISSN - 1440-1703
pISSN - 0912-3814
DOI - 10.1007/s11284-009-0652-z
Subject(s) - species richness , poaceae , habitat , herbarium , panicum , ecology , biology , photosynthesis , botany
For 383 Poaceae species harvested over the Japanese islands and stored as herbarium specimens along several decades, we determined C 3 and C 4 types of photosynthesis from leaf stable carbon isotope ratio (δ 13 C). Then, we sought the relationships between C 4 species richness and climatic factors or habitat types. Except for the two Panicum species ( P. lanuginosum and P. scoparium ) having the possibility of C 3 –C 4 intermediate, 227 and 154 species were classified into C 3 and C 4 . The C 4 species richness increased from northern to southern islands in Japan, positively correlated with mean annual air temperature. Greater C 4 species richness in the seashore habitats, and smaller C 4 species richness in the shaded, wet and highland habitats would be related to the photosynthetic responses to local environmental factors such as irradiance level and temperature regime. No difference of leaf δ‐value of C 3 Poaceae was obtained between the habitats with different soil water availability, suggesting the less importance of soil water availability on leaf water‐use efficiency in C 3 Poaceae species in Japan having humid climate. Additionally, possible effects of human activity around the harvested time or site on leaf δ‐value were estimated, because the habitat includes the sites with high human activity. Leaf δ‐value was decreased with sampling year, and it was higher in the densely inhabited district for both C 3 and C 4 . They are probably due to a historical decrease in the atmospheric δ‐value via increasing human activity, and high gas emission at the districts of high human density.