Submitted to: Society for Range Management Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 2/2/2003
Publication Date: 2/2/2003
Citation: DERNER, J.D., TISCHLER, C.R., POLLEY, H.W., JOHNSON, H.B. EFFECTS OF ELEVATED CO2 ON ABOVE- AND BELOW-GROUND GROWTH RESPONSES OF TWO VARIETIES OF MESQUITE. SOCIETY FOR RANGE MANAGEMENT MEETING ABSTRACTS. 2003. Interpretive Summary:
Technical Abstract: Seeds were collected from three individual trees of two different varieties of mesquite in Texas and New Mexico to investigate if atmospheric carbon dioxide (CO2) enrichment exaggerates intraspecific variation. Prosopis glandulosa var. glandulosa occurs in mesic environments as large, tall single-stemmed trees. In contrast, Prosopis glandulosa var. torryana occurs in xeric environments as short, multi-stem shrubs. Seeds of similar mass were planted in 0.05 m X 1.60 m pots filled with sandy loam soil. Seedlings were grown under optimal growth conditions and destructively harvested at 8, 16 and 24 days post-emergence. For all three harvest dates, CO2 X variety interactions were not significant for any growth response. At day 8, CO2 enhanced root mass, volume and surface area by 8-23%. Mass of cotyledons, stem, leaves and total above-ground mass were increased by 33-50% with elevated CO2. Below-ground growth responses to elevated CO2 were similar at day 16 (36-40%) and day 24 (30-40%), but above-ground responses were even more pronounced at day 24 (46-68%) than at day 16 (23-36%). Absence of significant interactions between CO2 and varieties of this invasive woody plant suggests that both varieties will respond in a similar positive manner to CO2 enrichment. It is uncertain, however, if the magnitude of this response will be fully realized under field conditions as prevailing environmental constraints may reduce responses to CO2 enrichment.