Spatial variability in soil heat flux at three Inner Mongolia steppe ecosystems
نویسندگان
چکیده
Closing the energy budget at flux measurement sites is problematic, even when the fetch extends over flat, homogeneous surfaces with low vegetation cover. We used the residual energy balance and ordinary least square (OLS) linear regression methods to quantify spatial variability in soil heat flux contributing to energy balance closure (EBC), by deploying a mobile energy system within the footprints of three Eddy-covariance towers located in the steppe of Inner Mongolia, China. The EBC at the study sites had a daily average residual of 8– 19 W m 2 with OLS slopes of 0.83–0.96. The EBC was better achieved at the wet site than at the dry site. The spatial variability in soil heat flux was 48 W m 2 (13% of Rn) during the day and 15 W m 2 (34%) at night, with an average of 29 W m 2 (24%) across the three sites. A 9% OLS slope difference due to this variability was recorded from our eight plot measurements. A large amount of missing energy (110 W m 2 at peak) could occur with decreasing OLS slope of 23% across the three grassland sites when soil heat flux is not taken into account. In particular, heat storage in the top soil layer not only influenced the magnitude of EBC, but also adjusted soil heat flux to match the ‘truth schedule’. Heat storage in the top soil layer comprised half of the soil heat flux when the heat flux plate was deployed at a depth of 30 mm. If this part of heat storage was neglected, the residual of EBC would increase as large as 60 W m 2 with OLS slope decreasing 9%. Comparing them with the multiple-location soil heat flux measurements, the single-location measurements from near the Eddy-covariance towers obtained a slightly better EBC with the OLS slope increasing by 4%. # 2008 Elsevier B.V. All rights reserved. avai lab le at www.sc iencedi rec t .com journal homepage: www.e lsev ier .com/ locate /agr formet
منابع مشابه
Energy balance and partition in Inner Mongolia steppe ecosystems with different land use types
Land use change and grassland degradation are two of the most critical problems ubiquitously found in arid and semi-arid areas in Northern China. Energy fluxes, including net radiation (Rn), latent heat flux (LE), sensible heat flux (H) and soil heat flux (G), were examined over an entire year (December 2005 to November 2006) in different steppe ecosystems – the steppe and cropland in Duolun an...
متن کاملBiophysical regulations of carbon fluxes of a steppe and a cultivated cropland in semiarid Inner Mongolia
An increasing amount of grasslands in Inner Mongolia of Northern China has been converted to cropland. The conversions in this extensive semiarid region have produced adverse ecological consequences at local and regional scales (e.g., dust storms). An important research need is to understand the fundamental ecosystem processes, such as energy and material fluxes, associated with the land conver...
متن کاملEvapotranspiration and soil water relationships in a range of disturbed and undisturbed ecosystems in the semi-arid Inner Mongolia, China
Aims Evapotranspiration (ET) is a key component of water balance and is closely linked to ecosystem productivity. In arid regions, large proportion of precipitation (PPT) is returned to the atmosphere through ET, with only a small amount available to plants. Our objective was to examine the variability in ET–soil water relationship based on a set of ecosystems that are representative for semi-a...
متن کاملEcosystem responses to mowing manipulations in an arid Inner Mongolia steppe: An energy perspective
Mowing for hay is a widely adopted practice for grasslands utilization and management. However, its effects on energy partitioning have not well been studied. Our primary objective was to examine the role of mowing as a disturbance factor acting on energy partitioning and relationships between community composition/structure and energy fluxes in a typical steppe ecosystem through a long-term fi...
متن کاملPrimary production and rain use efficiency across a precipitation gradient on the Mongolia Plateau.
Understanding how the aboveground net primary production (ANPP) of arid and semiarid ecosystems of the world responds to variations in precipitation is crucial for assessing the impacts of climate change on terrestrial ecosystems. Rain-use efficiency (RUE) is an important measure for acquiring this understanding. However, little is known about the response pattern of RUE for the largest contigu...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
دوره شماره
صفحات -
تاریخ انتشار 2008