Evapotranspiration over artificially planted shrub communities in the shifting sand dune area of the Tengger Desert, north central China

Abstract

Revegetation is a common method to combat desertification in arid and semi-arid areas worldwide. The objective of this study was to characterize the evapotranspiration (ET) of a 20-year-old revegetated area of the Tengger Desert. During the measurement period from 2009 to 2012, ET was measured by the eddy covariance technique. The result showed that the values for mean daily ET were 0.43, 0.39, 0.43 and 0.59 mm d À1 in 2009-2012, respectively. In the non-growing season, the diurnal ET variation showed a normal distribution with a maximum value occurring at noon, while it showed multimodal distribution trend occurred in a dry day and a unimodal trend in a wet day with a maximum value occurring at noon in the growing season. During the 4-year measurements, despite the large inter-annual variation of precipitation (annual mean precipitation of 164.4 ± 33.5 mm), the water loss through ET (667.5 mm) was almost equal to rainfall (657.8 mm), and the mean of ET/P was 1.01.The annual ET amounts were 153.6, 143.3, 156.2 and 214.4 mm y À1 in 2009-2012, respectively, with corresponding ratio between accumulated ET and precipitation (ET/P) of 1.03, 1.14, 0.82 and 1.12. This indicated that the annual ET amounts can be modified by the soil water storage, which led to water loss through ET exceeding the water input by precipitation in a drier year, and soil water can be replenished in a wetter year. Thus, the vegetation protection system using plantations of xerophyte shrubs in the present study area is a success with a trade-off of acceptable hydrological consequences that deserve to be popularized.

Vegetation restoration in dryland with shrub serves as a carbon sink: Evidence from a 13‐year observation at the Tengger Desert of Northern China

“…The 10 Hz raw data (concentrations of CO 2 and H 2 O, three‐dimensional wind vector and sonic virtual temperature) were collected with a data logger (CR3000, Campbell Scientific, Logan). The energy closure ratio of the EC system was above 79% (Gao et al, 2016), which indicated flux measurements reached a moderate level of robustness (Wilson et al, 2002).…”

Vegetation restoration in dryland with shrub serves as a carbon sink: evidence from a 13-year observation at the Tengger Desert of Northern China

“…The system energy closure ratio (defined as the ratio between the sums of turbulent and soil heat fluxes against radiant fluxes) was above 79% (Gao, et al, 2016), which indicated that flux measurements were reached moderate level of robustness (Wilson et al, 2002).…”

“…Piao et al (2009) found that it is also a very important carbon sink in China, with an average carbon sequestration of 10+-5gC.m -2 .y -1 . The saline shrub community in the Gurbantunggut desert (in arid land) were showed a small carbon sink with the annual carbon sequestration 26+-13gC.m -2 .y -1 (Liu et al, 2012(Liu et al, , 2016 and the arid shrub ecosystem near Baja California, Mexico was found a carbon source from measured results in 2002-2008 and annual carbon sequestration -79+-117 gC.m -2 .y -1 (Bell et al, 2012). Sites in the Mojave Desert in the USA and the scrub deserts of Mexico show net carbon uptake, with carbon sink rates of 40-120 gC.m -2 .y -1 , which is relatively close to the range of carbon sink intensities in our desert shrub artificial systems which mainly due to the switch between functioning as carbon sinks or sources in wet or dry years (Bell et al, 2012;Biederman et al, 2017;Liu et al, 2016, Xie et al, 2016.…”