Cao Yuanbo, Wang Baitian, Wei Tingting, Ma Hua
College of Soil and Water Conservation, Beijing Forestry University, Beijing, 100083, People's Republic of China.
China National Gold Group Corporation, Beijing, 100011, People's Republic of China.
Environ Monit Assess. 2016 Feb;188(2):80. doi: 10.1007/s10661-015-5057-6. Epub 2016 Jan 6.
Populus davidiana, Leuchtenbergia principis, and Pinus tabulaeformis are important greening tree species with a cosmopolitan distribution. However, the stoichiometric characteristics and element reserves of stands of these three species are not particularly clear. In this study, we conducted a plot-level investigation of forest stands of these species in the loess area; these have been closed forest stands more than 28 years. Trees were sampled from an area of 50 m × 20 m (in 6, 8, and 9 plots, respectively), which was sufficient for shrub (2 m × 2 m), herbal species, and litter (1 m × 1 m) investigations. The C, N, and P concentrations and the C:N:P stoichiometry in five different soil layers (0-10 cm, 10-20 cm, 20-30 cm, 30-50 cm, and 50-100 cm) and in the leaves, stems, branches, and roots of the plants were examined. The soil element concentrations and density were affected by soil depth. The element content had a significantly negative correlation with soil depth, and element density differed significantly among the soil layers. A particular element in a particular organ differed significantly between the forest stands, and the same element in different organs of the same stand was also significantly different. The C, N, and P element reserves in the soil were considerably higher than in the plants. Our results indicate that there are different stoichiometric characteristics and element reserves of the three stands in a closed forest on the Chinese loess plateau, which may provide a reference when we develop and optimize the structure of forest stands.
山杨、光枝玉、油松是分布广泛的重要绿化树种。然而，这三种树种林分的化学计量特征和元素储量尚不清楚。本研究对黄土地区这三种树种的林分进行了样地调查；这些林分已封育28年以上。从50米×20米的区域（分别在6个、8个和9个样地）采集树木样本，该区域足以进行灌木（2米×2米）、草本植物和凋落物（1米×1米）调查。测定了五个不同土壤层（0 - 10厘米、10 - 20厘米、20 - 30厘米、30 - 50厘米和50 - 100厘米）以及植物的叶、茎、枝和根中的碳、氮、磷浓度及C:N:P化学计量比。土壤元素浓度和密度受土壤深度影响。元素含量与土壤深度呈显著负相关，且各土壤层间元素密度差异显著。不同林分中特定器官的特定元素存在显著差异，同一林分不同器官中的相同元素也有显著差异。土壤中的碳、氮、磷元素储量显著高于植物。我们的研究结果表明，中国黄土高原封闭森林中这三种林分具有不同的化学计量特征和元素储量，可为林分结构的优化和发展提供参考。
