Plant aboveground biomass data: Traits: Biomass Allocation Trends in Old Field in Relation to Gradients of Succesional Age and Soil Nitrogen

The objective of this experiment is to assess biomass allocation trends in the field in relation to gradients of successional age and soil nitrogen. This objective was approached in three ways: A) 37 old fields of various ages were surveyed for above and below ground biomass, soil N, and light penetration. Five strips (1m x 10cm) were clipped in each field for above ground biomass (sorted to grasses and forbs; then sorted to leaf and stem), and 3 root cores (down to 30cm) taken per strip (rinsed, dried and weighed). Two light measurements and one pooled (3 cores) soil N sample (for available and total N) were taken per strip. B) 35 abundant species of known successional status were harvested from the field (usually 15 individuals per species), including roots contained in a core 20x30cm, dried, sorted to stem, leaf, and root, and weighed. These data can be combined with the old field survey results (E014) to estimate successional trends in allocation. C) Root cores will be taken from microplots in fields A, B, C, and D, all treatments. This will be an estimate of root biomass to be combined with the above ground samples (E001) to assess root-shoot trends in response to manipulation of soil N in fields of different age.本实验旨在探究野外生物量分配（biomass allocation）格局与演替年龄（successional age）梯度及土壤氮素（soil nitrogen）梯度的关联关系。本研究目标通过以下三种途径实现： A) 对37个不同演替年龄的撂荒地开展调查，测定其地上生物量（above ground biomass）、地下生物量（below ground biomass）、土壤氮含量及光照穿透率（light penetration）。每个样地内设置5条1m×10cm的样带以采集地上生物量样本：先将样本划分为禾草（grasses）与非禾草草本（forbs），再进一步区分为叶片与茎秆组分；每条样带采集3个深度达30cm的根芯（root cores），经冲洗、烘干后称重。每条样带同时开展2次光照强度测定，并采集1份由3个根芯混合而成的土壤氮样本，用于检测有效氮（available nitrogen）与全氮（total nitrogen）含量。 B) 采集35个已知演替地位（successional status）的常见野外物种样本（每个物种通常采集15个个体），采集范围包含20cm×30cm根芯（root cores）内的根系；所有样本经烘干后，按茎、叶、根组分分离并称重。该数据集可与撂荒地调查结果（E014）结合，以估算生物量分配的演替趋势。 C) 从A、B、C、D四个样地的微样方中采集根芯（root cores），覆盖所有实验处理组。该样本可用于估算根系生物量，并与地上生物量样本（E001）结合，以评估不同演替年龄样地中，土壤氮素调控下的根冠分配趋势。