Soil DIC uptake and fixation in Pinus taeda seedlings and its C contribution to plant tissues and ectomycorrhizal fungi

摘要: Plants can acquire carbon from sources other than atmospheric dioxide (CO(2)), including soil-dissolved inorganic (DIC). Although the net flux of CO(2) is out root, soil DIC be taken up by transported within plant, and fixed either photosynthetically or anaplerotically plant tissues. We tested ability Pinus taeda L. seedlings exposed to (13)C-labeled two NH(4)(+) availability regimes take fix DIC. also measured concentration distribution mycorrhizal tissues, quantified contribution whole-plant (C) gain. Seedlings labeled were significantly enriched in (13)C compared with unlabeled (6.7 versus -31.7 per thousand). Fixed was almost evenly distributed between above- belowground biomass (55 45%, respectively), but unevenly among Aboveground, stem tissue contained 65% represented only 27% aboveground biomass, suggesting corticular photosynthesis preferential allocation. Belowground, had greatest effect (measured as enrichment) on C pool rapidly growing nonmycorrhizal roots. Soil contributed approximately 0.8% gain, 1.6% observed a slight nonsignificant increase both relative gain NH(4)(+)-fertilized seedlings. Increased altered types increased amount ectomycorrhizal roots 130% unfertilized did not fixation roots, that assimilation may concentrated fungal reflecting greater anaplerotic demands. likely contribute small forest trees, it important processes specific such newly formed stems fine assimilating NH(4)(+).