Mp. Mcclaran et Gr. Mcpherson, CAN SOIL ORGANIC-CARBON ISOTOPES BE USED TO DESCRIBE GRASS-TREE DYNAMICS AT A SAVANNA-GRASSLAND ECOTONE AND WITHIN THE SAVANNA, Journal of vegetation science, 6(6), 1995, pp. 857-862
We evaluated the use of soil organic carbon (SOC) isotopes to describe
grass-tree dynamics at locations at the savanna-C-4 grassland ecotone
and within a temperate semiarid Quercus savanna in southeastern Arizo
na, USA. SOC will not describe grass-tree dynamics at locations within
the savanna because isotope composition near the soil surface does no
t correspond with the overlying vegetation and recent C-3 carbon has b
een deposited at deep soil depths with no C-4 analog. In contrast, SOC
can describe grass-tree dynamics at the savanna-grassland ecotone bec
ause isotope composition near the soil surface corresponds with overly
ing vegetation and significant deep soil deposition of C-3 carbon was
not apparent. At the ecotone, trees became established in the last 700
-1700 years. There is no evidence to suggest an unstable grass-tree mi
xture at the ecotone since that time.