Soil organic carbon and total nitrogen pools in permafrost zones of the Qinghai-Tibetan Plateau

Abstract

There are several publications related to the soil organic carbon (SOC) on the Qinghai-Tibetan Plateau (QTP). However, most of these reports were from different parts of the plateau with various sampling depth. Here, we present the results from a systematic sampling and analysis of 200 soil pits. Most of the pits were deeper than 2 m from an east-west transect across the plateau. The SOC and total nitrogen (TN) pools of the 148 × 104 km2, the area of the permafrost zone, for the upper 2 m soils calculated from the vegetation map were estimated to be 17.07 Pg (interquartile range: 11.34–25.33 Pg) and 1.72 Pg (interquartile range: 1.08–2.06 Pg), respectively. We also predicted the distribution of land cover types in 2050 and 2070 using decision tree rules and climate scenarios, and then predicted SOC and TN pools of this region. The results suggested that the SOC and TN pools will decrease in the future. The results not only contribute to the carbon and nitrogen storage and stocks in the permafrost regions as a whole but most importantly, to our knowledge of the possible changes of C and N storage on the QTP in the future.

Climate warming accelerates temporal scaling of grassland soil microbial biodiversity

“…This is most likely due to the short experimental period (6 years), which was insufficient to allow rapid phylogenetic change, and/or due to the regional species pool, which has low phylogenetic diversity 2 . Taken together, these results suggest that experimental warming significantly promoted the temporal scaling rates of soil bacterial and fungal diversity, consistent with the MTE prediction that or ganisms have faster rates of ecological and evolutionary processes at higher environmental temperatures 29,30,31 .…”

“…Based on the metabolic theory of ecology (MTE), rising temperature should have profound effects on the temporal scaling of biodiversity. MTE predicts that the metabolism of organisms, population growth rates and species diversity increase exponentially with environmental temperature 29,30,31 . Therefore, it is expected that climate warming will increase the rates of ecological and evolutionary processes 30 , including the rates of genetic mutation, speciation and interactions.…”

Characteristic, changes and impacts of permafrost on Qinghai-Tibet Plateau

“…对青藏高原162.7万km 2 的草地生态系统的土壤有 机碳储量进行估算, 结果表明0.75 m深度的有机碳储量 为33.52 Pg [41] ; 同时有研究结果表明, 青海省和西藏地 区草地生态系统表层1 m的有机碳储量为7.4 Pg [42] ; 此 后关于高原有机碳的储量研究主要集中于多年冻土区, 高原多年冻土区2 m的土壤有机碳储量在28 Pg左右, 而 0~25 m深的土层可能有160 Pg有机碳 [43] ; 在青海省和 西藏地区多年冻土区草地生态系统表层1 m的土壤有 机碳储量为7.44 Pg, 表层2 m的储量为10.68 Pg, 3 m深 为13.39 Pg [44] ; 通过200个土壤探坑资料, 并根据更新后 的植被和土壤资料, 计算得到多年冻土区表层2 m的有 机碳储量为17 Pg左右(表1). 同时该研究发现, 由于土 层分布不均、区域差异大等原因, 高原土壤有机碳的 储量不确定范围很大 [45] . 青藏高原多年冻土区土壤活性有机碳的比例随着 海拔的增加而增加, 到4800~4950 m后则快速下降 [46] , 其中多年冻土区土壤活性碳的含量和比例均高于非多 年冻土区 [47] , 高寒草地下土壤轻组碳比例可占9%2 0%, 计算得活性碳库为0.5%~3.65% [48] .…”

Profile distributions of soil organic carbon fractions in a permafrost region of the Qinghai–Tibet Plateau

“…These three vegetation types are common, representative, and widespread on the QTP. [40][41][42] The plant communities in the ASM and AM were dominated by sedge species (e.g., Kobresia pygmaea); those in the AS, by grasses (mainly consisting of Stipa capillata, Elymus nutans, Poa crymophila, and Festuca ovina) and forbs. 43 locations at each site, two soil pits were excavated to a depth of 200 cm or into permafrost by shovel, spade, and power drill.…”