Page 15 - 《高原气象》2022年第5期

高 原 气 象 41 卷
1108

Impact of Soil Organic Matter Content on Soil Moisture and Temperature

at Different Depths in the Central Qinghai-Xizang Plateau

1，3
FU Qing ，YANG Kun ，ZGENG Donghai ，CHEN Yingying 3
2，3
3
（1. College of Atmospheric Sciences，Lanzhou University，Lanzhou 730000，Gansu，China；
2. Department of Earth System Science，Tsinghua University，Beijing 100084，China；
3. National Qinghai-Xizang Plateau Data Center，Institute of Qinghai-Xizang Plateau Research，
Chinese Academy of Sciences，Beijing 100101，China）

Abstract：Soil organic matter content is relatively high in the central and eastern Qinghai-Xizang Plateau，which
may change the soil hydrothermal properties and thus affect the transport of soil water and heat. However，there
is still a lack of systematic quantification on how soil organic matter content affects soil moisture and temperature
profiles as well as their spatial heterogeneity on the Qinghai-Xizang Plateau. In this study，this effect is quanti‐
fied using the in situ soil moisture and temperature data as well as soil organic carbon contents collected at 32 sta‐
tions under similar climatic conditions in Naqu. The soil temperature and moisture dynamics in different depths
（5，10，20 and 40 cm）with different organic matter contents and their spatial heterogeneity during the warm sea‐
son were systematically analyzed. It is found that the soil organic matter content is a key factor determining the
spatial distribution of soil moisture at 5 cm and 10 cm depth and temperature at 5 cm depth. The soil organic mat‐
ter content also significantly affects the profile characteristics and dynamics of soil moisture from the surface to
20 cm depth. A higher organic matter content tends to produce a greater water holding capacity，resulting in high‐
er soil moisture contents from the surface to 20 cm depth. In addition，the profile characteristics and variations of
soil temperature are largely influenced by the soil organic matter content as well. The higher organic matter con‐
tent leads to lower thermal inertia，smaller amplitudes of diurnal soil temperature variation，and thus longer time
lag of heat transfer to the deeper layers. The findings of this study will provide an important reference for improv‐
ing the soil moisture and temperature simulations of land surface models in alpine meadows.
Key words：Qinghai-Xizang Plateau；soil organic matter；soil moisture；soil temperature