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Title: USING SEASONAL WATER AVAILABILITY TO PREDICT PERCENTAGES OF COOL AND WARM SEASON GRASSES

Author
item WINSLOW, JERRY - TEXAS TECH UNIV
item Hunt Jr, Earle

Submitted to: Society for Range Management Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 10/29/2003
Publication Date: 1/29/2004
Citation: Winslow, J.C., Hunt, E.R. 2004. Using seasonal water availability to predict percentages of cool and warm season grasses [abstract]. 57th Annual Meeting of the Society for Range Management. p. 223.

Interpretive Summary:

Technical Abstract: We hypothesize that the major influence on the distribution of cool season (C3 photosynthetic pathway) and warm season (C4 photosynthetic pathway) grasses may be the seasonal timing of water availability with respect to the different growing seasons. Maximum and minimum air temperatures are used to define the start and end of the growing seasons, determine water lost by transpiration, and estimate water use efficiency. The percentage of cool season grasses is determined by the daily sum of C3 water use efficiency times the amount of water available to be transpired, normalized by the sums for both C3 and C4 plants. At various locations, climatic variations in rainfall and temperature would result the percentage of cool season grasses ranging from about 0 to 100%, therefore the average percentage from 1983 to 1996 was compared to measured data for grasslands throughout the world. The overall R-squared between predictions and all data was 0.71 and the R-squared for just regions that are classified as mixed cool and warm season grasses is 0.54. This model is as good as the best statistical models of cool and warm season grass distributions. However, since this model is based on the physiological differences, this model is more applicable to predicting the effects of global climate change.