Data from: Leaf meristems: an easily ignored component of the response to human disturbance in alpine grasslands

Grazing and fencing are two important factors that influence productivity and biomass allocation in alpine grasslands. The relationship between root (R) and shoot (S) biomass and the root:shoot ratio (R/S) are critical parameters for estimating the terrestrial carbon stocks and biomass allocation mechanism responses to human activities. Previous studies have often used the belowground:aboveground biomass ratio (Mb/Ma) to replace the R/S in alpine ecosystems. However, these studies may have neglected the leaf meristem biomass, which belongs to the shoot but occurs below the soil surface, leading to a significant overestimation of the R/S ratio. We conducted a comparative study to explore the differences between the R/S and Mb/Ma at both the species (Stipa purpurea, Carex moorcroftii, and Artemisia nanschanica) and community levels on a Tibetan alpine grassland with grazing and fencing management blocks. The results revealed that the use of the Mb/Ma to express the R/S appeared to overestimate the actual value of the R/S, both at species and community levels. For S. purpurea, the Mb/Ma was three times higher than the R/S. The Mb/Ma was approximately two times higher than the R/S for the species of C. moorcroftii and A. nanschanica and at the community level. The relationships between the R-S and Mb-Ma exhibited different slopes for the alpine plants across all the management practices. Compared to the fenced grasslands, the plants in the grazing blocks not only allocated more biomass to the roots but also to the leaf meristems. The present study highlights the contribution of leaf meristems to the accurate assessment of shoot and belowground biomasses. The R/S and Mb/Ma should be cautiously used in combination in the future research. The understanding of the distinction between the R-S and Mb-Ma may help to improve the biomass allocation mechanism response to human disturbances in an alpine area.

放牧与围封是影响高寒草地生产力与生物量分配格局的两大关键驱动因素。根（root, R）与地上部分（shoot, S）生物量的关系，以及根冠比（root:shoot ratio, R/S）是估算陆地碳储量、解析生物量分配机制对人类活动响应的核心参数。既往研究在高寒生态系统中常以地下地上生物量比（belowground:aboveground biomass ratio, Mb/Ma）替代根冠比（R/S），但这类研究往往忽略了隶属于地上部分却分布于土壤表层下的叶分生组织生物量，进而导致根冠比的估算值被显著高估。本研究在青藏高原高寒草地的放牧与围封管理样地中，分别在物种水平（紫花针茅（Stipa purpurea）、青藏薹草（Carex moorcroftii）、南艾蒿（Artemisia nanschanica））与群落水平开展比较研究，探究R/S与Mb/Ma二者的差异。研究结果显示，无论在物种水平还是群落水平，用Mb/Ma替代R/S均会导致根冠比的估算值被高估。其中紫花针茅的Mb/Ma是R/S的3倍；青藏薹草、南艾蒿以及群落整体的Mb/Ma则约为R/S的2倍。在所有管理措施下，高寒植物的根-地上生物量关系与地下-地上生物量关系呈现出不同的斜率。相较于围封草地，放牧样地中的植物不仅会向根系分配更多生物量，同时也会向叶分生组织分配更多生物量。本研究强调了叶分生组织在精准估算地上与地下生物量中的重要作用。未来研究中应谨慎联合使用R/S与Mb/Ma两类指标。明晰根-地上生物量关系与地下-地上生物量关系的差异，有助于深化对高寒区域生物量分配机制响应人类活动的理解。