Data from: Estimating soil pCO2 using paleosol carbonates: implications for the relationship between primary productivity and faunal richness in ancient terrestrial ecosystems

In this paper we present a method for estimating soil pCO2 in ancient environments using the measured carbon-isotope values of pedogenic carbonates and plant-derived organic matter. The validity of soil pCO2 estimates proves to be highly dependent on the organic δ13C values used in the calculations. Organic matter should be sourced from the same paleosol profiles as sampled carbonates to yield the most reliable estimates of soil pCO2. In order to demonstrate the potential use of soil pCO2 estimates in paleoecological and paleoenvironmental studies, we compare samples from three Upper Jurassic localities. Soil pCO2 estimates, interpreted as a qualitative indicator of primary paleoproductivity, are used to rank the Late Jurassic terrestrial environments represented by the Morrison Formation in western North America, the informally named Lourinhã formation in Western Europe, and the Stanleyville Group in Central Africa. Because modern terrestrial environments show a positive correlation between primary productivity and faunal richness, a similar relationship is expected in ancient ecosystems. When the relative paleoproductivity levels inferred for each study area are compared with estimates of dinosaur generic richness, a positive correlation emerges. Both the Morrison and Lourinhã formations have high inferred productivity levels and high estimated faunal richness. In contrast, the Stanleyville Group appears to have had low primary productivity and low faunal richness. Paleoclimatic data available for each study area indicate that both productivity and faunal richness are positively linked to water availability, as observed in modern terrestrial ecosystems.

本研究提出了一种利用成土碳酸盐（pedogenic carbonates）与植物源有机质（plant-derived organic matter）的实测碳同位素值，估算古环境土壤pCO₂的方法。研究表明，土壤pCO₂估算结果的可靠性高度依赖于计算中所采用的有机质δ¹³C值。为获得最可靠的土壤pCO₂估算结果，有机质样品应与碳酸盐样品采自同一古土壤剖面。
为展示土壤pCO₂估算在古生态与古环境研究中的应用潜力，本研究对三处晚侏罗世（Upper Jurassic）地层的样品进行了对比分析。将土壤pCO₂估算值作为古初级生产力的定性指示指标，我们对三个研究区所代表的晚侏罗世陆相环境进行了排序：北美西部的莫里逊组（Morrison Formation）、西欧非正式命名的洛里尼亚组（Lourinhã Formation）以及中非的斯坦利维尔群（Stanleyville Group）。
由于现代陆相环境中初级生产力与动物群丰富度呈正相关关系，因此推测古生态系统中也存在类似关联。将各研究区推断的相对古初级生产力水平与恐龙属多样性估算值进行对比后，二者呈现出显著正相关。莫里逊组与洛里尼亚组均被推断为高生产力水平，且对应较高的动物群丰富度；与之相反，斯坦利维尔群的初级生产力与动物群丰富度均较低。各研究区已有的古气候数据显示，正如现代陆相生态系统所见，古初级生产力与动物群丰富度均与水资源可获得性呈正相关关系。