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Root dynamics in an artificially constructed regenerating longleaf pine ecosystem are affected by atmospheric CO2 enrichment
Environmental and Experimental Botany ( IF 5.7 ) Pub Date : 2001-08-01 , DOI: 10.1016/s0098-8472(01)00084-3
S G. Pritchard 1 , M A. Davis , R J. Mitchell , S A. Prior , D L. Boykin , H H. Rogers , G B. Runion
Affiliation  

Differential responses to elevated atmospheric CO(2) concentration exhibited by different plant functional types may alter competition for above- and belowground resources in a higher CO(2) world. Because C allocation to roots is often favored over C allocation to shoots in plants grown with CO(2) enrichment, belowground function of forest ecosystems may change significantly. We established an outdoor facility to examine the effects of elevated CO(2) on root dynamics in artificially constructed communities of five early successional forest species: (1) a C(3) evergreen conifer (longleaf pine, Pinus palustris Mill.); (2) a C(4) monocotyledonous bunch grass (wiregrass, Aristida stricta Michx.); (3) a C(3) broadleaf tree (sand post oak, Quercus margaretta); (4) a C(3) perennial herbaceous legume (rattlebox, Crotalaria rotundifolia Walt. ex Gemel); and (5) an herbaceous C(3) dicotyledonous perennial (butterfly weed, Asclepias tuberosa L.). These species are common associates in early successional longleaf pine savannahs throughout the southeastern USA and represent species that differ in life-form, growth habit, physiology, and symbiotic relationships. A combination of minirhizotrons and soil coring was used to examine temporal and spatial rooting dynamics from October 1998 to October 1999. CO(2)-enriched plots exhibited 35% higher standing root crop length, 37% greater root length production per day, and 47% greater root length mortality per day. These variables, however, were enhanced by CO(2) enrichment only at the 10-30 cm depth. Relative root turnover (flux/standing crop) was unchanged by elevated CO(2). Sixteen months after planting, root biomass of pine was 62% higher in elevated compared to ambient CO(2) plots. Conversely, the combined biomass of rattlebox, wiregrass, and butterfly weed was 28% greater in ambient compared to high CO(2) plots. There was no difference in root biomass of oaks after 16 months of exposure to elevated CO(2). Using root and shoot biomass as a metric, longleaf pine realized the greatest and most consistent benefit from exposure to elevated CO(2). This finding suggests that the ability of longleaf pine to compete with sand post oak, a common deciduous tree competitor, and wiregrass, the dominant understory herbaceous species, in regenerating ecosystems may be significantly enhanced by rising atmospheric CO(2) concentrations.

中文翻译:

人工构建的再生长叶松生态系统中的根系动态受大气 CO2 富集的影响

不同植物功能类型对大气 CO(2) 浓度升高的不同反应可能会改变在较高 CO(2) 世界中对地上和地下资源的竞争。由于 C 分配到根部通常比 C 分配到 CO(2) 富集生长的植物中的枝条更受青睐,因此森林生态系统的地下功能可能会发生显着变化。我们建立了一个室外设施,以检查升高的 CO(2) 对五种早期演替森林物种的人工构建群落中根系动态的影响:(1) C(3) 常绿针叶树(长叶松、沼泽松);(2) C(4) 单子叶束草(wiregrass, Aristida stricta Michx.);(3) C(3)阔叶树(沙柱橡树,Quercus margaretta);(4) C(3) 多年生草本豆科植物 (rattlebox, Crotalaria rotundifolia Walt. ex Gemel);(5) 一种草本 C(3) 双子叶多年生植物(蝴蝶杂草,Asclepias tuberosa L.)。这些物种是整个美国东南部早期演替长叶松稀树草原的常见伙伴,代表了生命形式、生长习性、生理学和共生关系不同的物种。从 1998 年 10 月到 1999 年 10 月,使用微根管和土壤取芯的组合来检查时间和空间生根动态。富含 CO(2) 的地块表现出 35% 的直立根作物长度,37% 的每天根长产量和 47每天更高的根长死亡率。然而,这些变量仅在 10-30 厘米深度由 CO(2) 富集增强。相对根周转率(通量/立作物) 升高的 CO(2) 没有变化。种植后十六个月,与环境 CO(2) 地块相比,高架松树的根生物量高 62%。相反,与高 CO(2) 地块相比,响尾蛇、线草和蝴蝶杂草的组合生物量在环境中高 28%。暴露于升高的 CO(2) 16 个月后,橡树的根生物量没有差异。使用根和芽生物量作为度量标准,长叶松从暴露于升高的 CO(2) 中实现了最大和最一致的好处。这一发现表明,长叶松在再生生态系统中与沙柱橡树(一种常见的落叶树竞争者)和铁丝草(主要的林下草本植物物种)竞争的能力可能会因大气 CO(2) 浓度上升而显着增强。与高 CO(2) 地块相比,蝴蝶杂草在环境中高 28%。暴露于升高的 CO(2) 16 个月后,橡树的根生物量没有差异。使用根和芽生物量作为衡量标准,长叶松实现了暴露于升高的 CO(2) 中最大和最一致的好处。这一发现表明,长叶松在再生生态系统中与沙柱橡树(一种常见的落叶树竞争者)和铁丝草(主要的林下草本植物物种)竞争的能力可能会因大气 CO(2) 浓度上升而显着增强。与高 CO(2) 地块相比,蝴蝶杂草在环境中高 28%。暴露于升高的 CO(2) 16 个月后,橡树的根生物量没有差异。使用根和芽生物量作为度量标准,长叶松从暴露于升高的 CO(2) 中实现了最大和最一致的好处。这一发现表明,长叶松在再生生态系统中与沙柱橡树(一种常见的落叶树竞争者)和铁丝草(主要的林下草本植物物种)竞争的能力可能会因大气 CO(2) 浓度上升而显着增强。长叶松从暴露于升高的 CO(2) 中实现了最大和最一致的好处。这一发现表明,长叶松在再生生态系统中与沙柱橡树(一种常见的落叶树竞争者)和铁丝草(主要的林下草本植物物种)竞争的能力可能会因大气 CO(2) 浓度上升而显着增强。长叶松从暴露于升高的 CO(2) 中实现了最大和最一致的好处。这一发现表明,长叶松在再生生态系统中与沙柱橡树(一种常见的落叶树竞争者)和铁丝草(主要的林下草本植物物种)竞争的能力可能会因大气 CO(2) 浓度上升而显着增强。
更新日期:2001-08-01
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