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.

放牧与围栏封育是影响高寒草原生产力与生物量分配格局的两大核心调控因素。根（R）与地上部（S）生物量的相关关系，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关键参数。以往针对高寒生态系统的研究常以地下-地上生物量比（belowground:aboveground biomass ratio, Mb/Ma）替代根冠比，但此类研究往往忽略了隶属于地上部却分布于地下土层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原的放牧与围栏封育样地中，分别在物种水平（紫花针茅*Stipa purpurea*、青藏薹草*Carex moorcroftii*、南艾蒿*Artemisia nanschanica*）与群落水平开展对比研究，以解析根冠比与地下-地上生物量比的差异。研究结果显示，无论在物种还是群落水平，用地下-地上生物量比替代根冠比均会高估根冠比的真实值：其中紫花针茅的地下-地上生物量比为根冠比的3倍；青藏薹草、南艾蒿以及群落整体的地下-地上生物量比约为根冠比的2倍。不同管理措施下的高寒植物，其根冠比与地下-地上生物量比的相关关系斜率存在显著差异。相较于围栏封育样地，放牧样地中的植物不仅会将更多生物量分配至地下根系，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对于精准估算地上部与地下生物量的重要意义，未来相关研究应谨慎联合使用根冠比与地下-地上生物量比。明晰根冠比与地下-地上生物量比的差异，有助于深化对高寒区域生物量分配机制响应人类干扰的认知。