ROA/RUI: Use of Stable Isotopes of Carbon in Vegetation and Soil Organic Matter to Assess Vegetation Change in North American Prairies

北方C_3和C_4禾草生产有机质的研究 美洲大草原拥有独特的同位素特征。 这些 标签显示基于遗传和环境的变异 这在理论上是很好理解的，但 具有良好的生态性。 标签以 以定量可预测的方式向更高的营养级发展， 土壤有机质（SOM）的变化。 将研究由C4和C3系统组成的草原， 建立成分之间定量关系， 比例生产力，生物量δ 13 C，生物化学 组成，和SOM δ 13 C。 分析粒度 组分和土壤团聚体将表明是否SOM和 植被处于稳定状态或演替。 比较 在许多大草原中， 在最近的过去和过去的一段时间里， 一千年 短草中的细粒土和粗粒土， 将比较高草系统，并确定 植硅体是否可以用来区分 短草和高草组分。 自然的范围 植物和隔室中发生的δ 13 C值将是 记录并与生长形式和环境因素有关。 研究已知土地使用历史的大草原和老田地 将允许估计颗粒尺寸的周转率 级分和土壤团聚体。 分析了几个迟到的 将开展更新世和全新世古土壤研究。

Organic matter produced by C3 and C4 grasses in North American prairies possesses distinct isotopic signatures. These labels show genetically and environmentally based variation which is fairly well understood theoretically but not characterized well ecologically. The labels are transmitted in a quantitatively predictable manner to higher trophic levels and, in a less understood manner, to soil organic matter (SOM). Prairies comprising C4 and C3 systems will be studied to establish quantitative relationships among composition, proportional productivity, biomass delta 13C, biochemical composition, and SOM delta 13C. Analysis of particle size fractions and soil aggregates will indicate whether SOM and vegetation are in a steady state or successional. Comparisons among many prairies may show the presence of any consistent directional change in composition during the recent past and last 1,000 years. Fine and course grained soils in shortgrass and tallgrass systems will be compared and it will be determined whether or not phytoliths can be used to distinguish between shortgrass and tallgrass components. The range of naturally occurring delta 13C values in plants and compartments will be documented and related to growth forms and environmental factors. Studies of prairies and old fields with known land use histories will allow an estimation of rates of turnover of particle size fractions and soil aggregates. An analysis of several late Pleistocene and Holocene paleosols will be undertaken.