Coarse Roots and Rock Content in Oak, Hemlock, and Ash Stands at Harvard Forest 2020

When collecting soil samples in the very rocky soils of the Harvard Forest, researchers are forced to core the soil away from rocks. Thus, the resulting samples tend to underestimate the rock content of the soil and overestimate the sand, silt, and other fine particles content. When scaling the results to a spatial area larger than the sample’s (e.g., m2, hectare) it is important to know the actual rock content of the soil to apply the right correction factor. Therefore, we dug pits in three different stands at the Harvard Forest to determine the rock content. At the same time we also collected coarse roots (>2mm diameter) to measure their biomass, which can’t be easily done using the usual soil coring techniques.

在哈佛森林（Harvard Forest）的多岩土壤中采集土壤样品时，研究人员需避开石块开展土壤钻取操作。由此得到的样品往往会低估土壤的石块含量，同时高估砂土、粉粒及其他细颗粒的占比。当将研究结果外推至大于样品尺度的空间区域（例如平方米、公顷）时，明确土壤的实际石块含量以选取适配的校正因子至关重要。为此，研究团队在哈佛森林的三个不同林分中开挖土壤剖面坑，用以测定土壤石块含量。与此同时，我们还采集了直径大于2毫米的粗根以测定其生物量——该环节难以通过常规土壤钻取技术完成。