BNF = biological nitrogen fixation
N = soil nitrogen availability
C:N = carbon-nitrogen ratio of leaves
G = grazing intensity
B = browsing intensity
Rain = available soil water on a seasonal-annual basis
NPP = herb layer net primary production
L = standing fuel load
F
= frequency and intensity of fires.
Savanna
complexity affecting species composition and structure at continental-to-landscape
scales. Box and arrow sizes indicate relative importance of pool or process.
Solid arrows indicate primary direction of control and dotted arrows indicate
positive feed-back processes that maintain the "fertile" and
"infertile" stable states.