Sap flow of Artemisia ordosica and the influence of environmental factors in a revegetated desert area: Tengger Desert, China

Abstract

Abstract:Artemisia ordosica is considered as an excellent sand-fixing plant in revegetated desert areas, which plays a pertinent role in stabilizing the mobile dunes and sustaining the desert ecosystems. Stem sap flows of about 10-year-old Artemisia ordosica plants were monitored continuously with heat balance method for the entire growing season in order to understand the water requirement and the effects of environmental factors on its transpiration and growth. Environment factors such as solar radiation, air temperatures, relative humidity, wind speed and precipitation were measured by the eddy covariance. Diurnal and seasonal variations of sap flow rate with different stem diameters and their correlation with meteorological factors and reference evapotranspiration were analysed. At the daily time scale, there was a significantly linear relationship between sap flow rate and reference evapotranspiration with a correlation coefficient of R 2 D 0Ð6368. But at the hourly time scale, the relationship of measured sap flow rate and calculated reference evapotranspiration (ET 0 ) was affected by the precipitation. A small precipitation would increase the sap flow and the ET 0 ; however, when the precipitation is large, the sap flow and ET 0 decrease. Leaf area index had a coincident variation with soil water content; both were determined by the precipitation, and meteorological factors were the most significant factors that affected the sap flow of Artemisia ordosica in the following order: solar radiation > vapour pressure deficit > relative humidity > air temperature > wind speed. The close correlation between daily sap flow rate and meteorological factors in the whole growing season would provide us an accurate estimation of the transpiration of Artemisia ordosica and rational water-carrying capacity of sand dunes in the revegetated desert areas.

Seasonal and annual variation in transpiration of a dominant desert species, Haloxylon ammodendron, in Central Asia up‐scaled from sap flow measurement

“…As presented in Table I and Figure 4, J S was more closely correlated with ET 0 and PPFD than with T and VPD. Most studies have focused on the relationship between J S and other environmental factors such as PPFD and VPD alone (Adelman et al, 2008;Yue et al, 2008;Huang et al, 2010), and few on the relationship between J S and ET 0 (Bladon et al, 2006). The current study showed that ET 0 , the lumped variable that is usually used to reflect atmospheric water demand, was highly correlated with J S than did with single environment factor (Table I).…”

“…Previous studies on the response of sap flux-scaled transpiration are largely biased towards humid forest ecosystems, however (Granier et al, 1996(Granier et al, , 2000Loustau et al, 1996;Vertessy et al, 1997;Pataki et al, 1998;Oren et al, 1999a, b;Meinzer et al, 2001;Phillips and Oren, 2001;Wullschleger et al, 2001;Čermák et al, 2004;O'Brien et al, 2004;Schipka et al, 2005;Fiora and Cescatti, 2006;Gazal et al, 2006;Tang et al, 2006;Herbst et al, 2007;McCulloh et al, 2007;Kume et al, 2008;Oishi et al, 2008;Zheng and Wang, 2014). A few field-based studies on sap flux have considered arid and semi-arid ecosystems in the recent past (Pataki et al, 2000;Chang et al, 2006;Yue et al, 2008;O'Grady et al, 2009;Zhao et al, 2009;Huang et al, 2010;Liu et al, 2011;Guan et al, 2012;Naithani et al, 2012;Zheng and Wang, 2014), placing greatest emphasis on the temporal variation of sap flux, its relationship with environmental factors, and the regulation of stomata.…”

Sap flux-scaled transpiration and stomatal conductance response to soil and atmospheric drought in a semi-arid sagebrush ecosystem

“…Sap flux provides species-specific transpiration rates (Cermák et al, 1995;Ewers et al, 2002;Baldocchi, 2005) and can be used for continuous estimation of leaf and canopy g S and its response to environmental variables at sub-daily time scales (Köstner et al, 1992;Phillips and Oren, 1998;Ewers et al, 2007). However, prior studies on response of sap flux-scaled transpiration and g S are heavily biased from forest ecosystems (see Mackay et al, 2010 for a comprehensive list) with few sap flux field studies in arid and semi-arid ecosystems (e.g., Oren et al, 1999;Pataki et al, 2000;Dawson et al, 2007;Qu et al, 2007;Lei et al, 2010). This paucity of sap flux field data for arid and semi-arid shrub ecosystems needs to be addressed to improve current and future prediction of long term ecosystem carbon, water, and energy fluxes.…”

Orchard microclimate, tree water uptake and sweet cherry fruit quality under protected cropping

“…The U-shaped trend at location one is probably due to a lack of data underpinning the model, hence should not be given weight. It is expected that an increase in wind speed results in a reduction in the thickness of the boundary layer surrounding the leaves, subsequently increasing transpiration and therefore sap flows ( Lei et al., 2010 ). This is consistent with the modelled results of trees closer to the boundary than location one.…”