Premium
Seasonal water availability predicts the relative abundance of C 3 and C 4 grasses in Australia
Author(s) -
Murphy Brett P.,
Bowman David M. J. S.
Publication year - 2007
Publication title -
global ecology and biogeography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.164
H-Index - 152
eISSN - 1466-8238
pISSN - 1466-822X
DOI - 10.1111/j.1466-8238.2006.00285.x
Subject(s) - relative species abundance , abundance (ecology) , species richness , ecology , relative humidity , biology , geography , meteorology
Aim Numerous studies have examined the climatic factors that influence the abundance of C 4 species within the grass flora (C 4 relative species richness) in various regions throughout the world, but very few have examined the relative abundance of C 4 vs. C 3 grasses (C 4 relative abundance). We sought to determine the climatic factors that influence C 4 relative abundance throughout Australia. Location Australia (including Tasmania). Methods We measured C 4 relative abundance at 168 locations and measured δ 13 C (the abundance of 13 C relative to 12 C) of the bone collagen of 779 kangaroos collected throughout Australia, as bone collagen δ 13 C was assumed to be proportional to the relative abundance of C 4 grasses in the diet. Results Both C 4 relative abundance and kangaroo bone collagen δ 13 C were found to have a strong positive relationship with seasonal water availability, i.e. the distribution of rainfall in the C 4 vs. C 3 growing seasons (76% and 69% of deviance explained, respectively). There was clear evidence that seasonal water availability was a better predictor of both C 4 relative abundance and bone collagen δ 13 C than other climate variables such as mean annual temperature and January daily minimum temperature. However, seasonal water availability appeared to be a relatively poor predictor of C 4 relative species richness, which was most closely related to January daily minimum temperature (90% of deviance explained). Main conclusions Our results highlight the relatively poor relationship between C 4 relative abundance and C 4 relative species richness, and suggest that these two variables may be related to different climatic factors. They also suggest that caution is required when using C 4 relative species richness to infer the relative biomass and productivity of C 4 grasses on a global scale.