Influence of climate variability on plant production and N-mineralization in Central US grasslands

Publication Type:

Journal Article

Source:

JOURNAL OF VEGETATION SCIENCE, OPULUS PRESS UPPSALA AB, Volume 13, Number 3, MALMEN, S-740 11 LANNA, SWEDEN, p.383-394 (2002)

Keywords:

annual variation, ANPP, central grasslands region, environmental gradient, IGBP transect, mineralization, nitrogen flux, seasonal variation

Abstract:

We assessed the influence of annual and seasonal climate variability over soil organic matter (SOM), above-ground net primary production (ANPP) and in situ net nitrogen (N) mineralization in a regional field study across the International Geosphere Biosphere Programme (IGBP) North American mid-latitude transect (Koch et a]. 1995). We hypothesized that while trends in SOM are strongly correlated with mean climatic parameters, ANPP and net N-mineralization are more strongly influenced by annual and seasonal climate because they are dynamic processes sensitive to short-term variation in temperature and water availability. Seasonal and monthly deviations from long-term climatic means, particularly precipitation, were greatest at the semi-arid end of the transect. ANPP is sensitive to this climatic variability, but is also strongly correlated with mean annual climate parameters. In situ net N-mineralization and nitrification were weakly influenced by soil water content and temperature during the incubation and were less sensitive to seasonal climatic variables than ANPP, probably because microbial transformations of N in the soil are mediated over even finer temporal scales. We found no relationship between ANPP and in situ net N-mineralization. These results suggests that methods used to estimate in situ net N-mineralization are inadequate to represent N-availability across gradients where microbial biomass, N-immobilization or competition among plants and microbes vary.

Notes:

IGBP Terrestrial Transects Workshop, DARWIN, AUSTRALIA, JUL 12-16, 1999