Soil texture and carbon dynamics in savannah vegetation patches of Central Argentina

ADRIANA A. GILI; ROMÁN TRUCCO; SELENE NIVEYRO; MÓNICA BALZARINI; DANIEL ESTELRICH; ALBERTO QUIROGA; ELKE NOELLEMEYER

SOIL SCIENCE SOCIETY OF AMERICA JOURNAL

Soil Science Society of America Journal

Año: 2009

0361-5995

The present study was intended to contribute information on the relation between soil texture and plant community composition and the effect of interactions between texture and vegetation patch on soil carbon dynamics. Six sampling sites were chosen and vegetation census and soil sampling were carried out at each site in BC and UC patches, DI was determined for herbaceous species, FS and avoided grasses were calculated. Soil data included texture, BD, TOC, POC, IOC and FOC. Correspondence analysis showed that sandy and loamy sites did not share the same herbaceous species. We also found an interaction between vegetation patches and texture, with distinct vegetation composition in the same type of patch in different textures. DI was lower in UC than BC patches (0.86 vs. 1.7), but no effect of texture was found. TOC showed a positive relation with texture, the extremes were 9.0 vs. 16.3 g kg-1 for a loamy sand and loam respectively. Carbon fractions varied in their response to texture: while POC and IOC showed no clear trend according to texture, FOC contents followed a textural gradient. POC showed higher values in UC than BC (10.8 vs. 4.0 g kg-1). Difference between patches diminished with increasing clay contents. IOC was similar to POC, while FOC showed no effect of patch but was related to texture. The high proportion of POC in sandy soils (50 vs. 35% in a loam) makes these more susceptible to changes in C balance and might thus render them less resilient under grazing.