Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, China.
College of Life Sciences, Sichuan University, Chengdu, China.
PLoS One. 2020 Oct 22;15(10):e0240861. doi: 10.1371/journal.pone.0240861. eCollection 2020.
Shrubs play an important role in the global carbon cycle and are particularly sensitive to climate change. However, the altitudinal pattern of biomass allocation in mountainous shrubs and its responses to climate change are still unclear. In this study, biomass accumulation and allocation of the shrub community and their relationships with climatic factors were investigated in 331 sampling sites along an extensive altitudinal gradient (311-4911 m) in Southwest China. The results showed that the above-ground biomass (AGB) and the total biomass (TB) of the shrub community decreased quadratically (R2 = 0.107) and linearly (R2 = 0.024) from 9.86 to 0.15 kg·m-2 and 15.61 to 0.26 kg·m-2 with increasing altitude, respectively. However, the below-ground biomass (BGB) and TB of the herb layer increased quadratically with increasing altitudes (R2 = 0.136 and 0.122, respectively. P<0.001). The root/shoot ratio (R/S) of the community and its component synusiae increased gradually with increasing altitudes (P<0.001). The standardized major axis (SMA) indicated an isometric relationship between AGB and BGB for the whole shrub community, but allometric relationships were found for the shrub and herb layer. Redundancy analysis and Pearson correlation analysis showed that the biomass and R/S were significantly correlated with mean annual temperature (MAT), mean annual precipitation (MAP) and reconnaissance drought index (RDI). These findings indicate that shrub biomass allocation is strongly affected by the altitude, MAT and MAP and support the isometric relationship of AGB and BGB partitioning at the community level on mountainous shrub biomes.
灌木在全球碳循环中起着重要作用，对气候变化尤其敏感。然而，山地灌木生物量分配的海拔格局及其对气候变化的响应仍不清楚。本研究在 331 个采样点沿中国西南广泛的海拔梯度（311-4911 m）调查了灌木群落的生物量积累和分配及其与气候因子的关系。结果表明，灌木群落的地上生物量（AGB）和总生物量（TB）随海拔升高呈二次（R2 = 0.107）和线性（R2 = 0.024）减少，分别从 9.86 至 0.15 kg·m-2 和 15.61 至 0.26 kg·m-2。然而，草本层的地下生物量（BGB）和 TB 随海拔升高呈二次增加（R2 = 0.136 和 0.122，P<0.001）。群落和其组成丛的根/茎比（R/S）随海拔升高逐渐增加（P<0.001）。标准主轴分析（SMA）表明，整个灌木群落的 AGB 与 BGB 呈等比关系，但灌木层和草本层呈异速关系。冗余分析和 Pearson 相关分析表明，生物量和 R/S 与年平均温度（MAT）、年平均降水量（MAP）和探测干旱指数（RDI）显著相关。这些发现表明，灌木生物量分配受海拔、MAT 和 MAP 的强烈影响，并支持山地灌木生物群落中 AGB 和 BGB 分配的等比关系。
