Net ecosystem CO<sub>2</sub> exchange in Mojave Desert shrublands during the eighth year of exposure to elevated CO<sub>2</sub>

Jasoni, Richard L.; Smith, Stanley D.; Arnone, John A.

doi:10.1111/j.1365-2486.2005.00948.x

Cited by 132 publications

(111 citation statements)

References 24 publications

(35 reference statements)

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“…Phillips et al (2006) likely have the greatest contributions of roots to soil respiration. Thus, root respiration at the NDFF is unlikely the cause of increased soil or ecosystem respiration observed with elevated CO 2 (this report, Jasoni et al 2005). Contrary to the field results, L. tridentata root systems under elevated CO 2 were larger in 10-month old greenhouse seedlings (Table 7).…”

Section: The Nevada Desert Face Facilitymentioning

confidence: 99%

Effects of Elevated Co2 on Root Function and Soil Respiration in a Mojave Desert Ecosystem

Nowak¹

2007

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SUMMARYKey results from our research on responses of plants to elevated atmospheric CO 2 at the Nevada Desert FACE Facility (NDFF) and under controlled environment conditions include: Root Structure and FunctionMeasurements of root physiological characteristics and of arbuscular mycorrhizae indicate that:• Root respiration rates of two Mojave Desert shrubs, Ambrosia dumosa and Larrea tridentata, at the Nevada Desert FACE Facility (NDFF) over five growing seasons and L. tridentata seedlings in a greenhouse experiment were not significantly affected by elevated CO 2 .• The combination of elevated CO 2 and phosphorus reduction in greenhouse studies did not affect root growth or activity.• Specific root length was not significantly affected by CO 2 .• Extraradical hyphae (ERH) of arbuscular mycorrhizal fungi (AMF) varied seasonally, with ERH significantly lower at the end of the year. However, percent root colonization was not affected by sample date. These seasonal patterns of AMF are likely due to greater shrub demands for nutrients early in the year rather than changes in soil moisture.• AMF root colonization or ERH did not vary among soils beneath two shrubs, Ambrosia dumosa and Larrea tridentata, and their associated interspaces.• Beneath L. tridentata, immunoreactive glomalin related soil protein (IRSP) concentrations were significantly greater than all other microsites, and IRSP declined significantly over the year in L. tridentata soils. Significantly higher IRSP concentrations in the spring under L. tridentata may be due to turnover of residual ERH produced in the preceding wet year.• AMF root colonization, ERH lengths, and IRSP concentrations were not different between CO 2 treatments after 9 years of CO 2 treatment for samples collected in the spring and fall from three microsites: beneath Larrea tridentata and Ambrosia dumosa canopies and within shrub interspaces. Thus, our results from both the greenhouse and field experiment suggest that root systems of these species have not altered carbon use for respiration processes on a root length basis, nor have they grown in size to compensate for any nutrient limitations imposed by carbon fertilization. Furthermore, neither species showed increased allocation to arbuscular mycorrhizae under elevated CO 2 . AMF appear to explore all areas of the Mojave Desert equally even though nutrient availability varies considerably among microsites. Stimulated nitrogen cycling by other soil microbes in elevated CO 2 plots may eliminate the need for greater production of AMF by increasing nutrient availability in this system. Root GrowthMinirhizotron measurements of root growth reveal that:• Fine roots accumulate over long time periods in the Mojave Desert.• Elevated CO 2 had transitory effects on the accumulation of fine roots, where standing crop of fine roots accumulated to a larger extent under elevated CO 2 for up to 5 months. 1• The transitory greater accumulation of fine roots under elevated CO 2 was primarily due to lower rates of root loss through time.• After a we...

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Section: The Nevada Desert Face Facilitymentioning

confidence: 99%

Effects of Elevated Co2 on Root Function and Soil Respiration in a Mojave Desert Ecosystem

Nowak¹

2007

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“…SIC in the top 60 cm of soil increased by 5079245(SD) g C/m 2 per year over the 7 years of grazing removal, which is equivalent to a rate of C increase in the plantÁ soil system of 3669229(SD) g C/m 2 per year. Other studies have reported high rates of C uptake: 102Á127 g C/m 2 per year in the Mojave Desert (Jasoni et al 2005;Wohlfahrt et al 2008) and 62Á622 g C/m 2 per year in saline/ alkaline desert soils in China (Xie et al 2009). However, these rates of C increase are unusually large compared with some other studies (29 g C/m 2 per year (Reeder et al 2004) and 0.12Á0.42 g C/m 2 per year (Schlesinger et al 2009)), which are comparable to the rates of C uptake in forests (Waring et al 1998).…”

Section: Grassland Restoration Following Grazer Removalmentioning

confidence: 99%

Grazing exclusion alters ecosystem carbon pools in Alxa desert steppe

Niu

Hall

et al. 2011

New Zealand Journal of Agricultural Research

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The Alxa desert steppe has been strongly degraded by overgrazing, contributing c. 22% of the total springtime dust originating from Asia. Previous work in this region has focused on the impacts of grazer exclusion on restoration of vegetation and soil fertility, yet carbon dynamics are not well known. The effects of 7 years of grazer exclusion on carbon dynamics were studied and related to changes in vegetation and soil properties. Removal of grazing resulted in a significantly greater plant cover and aboveground plant biomass compared with areas that had been subject to grazing, but this had no effects on belowground plant biomass. Removal of grazing resulted in significantly decreased soil bulk density in the 0Á10 cm layer, increased soil water content (7% cf. 40%) and greater soil microbial biomass C (6% cf. 73%) compared with soils in the grazed area. Soil organic carbon (SOC) pools were lower and soil inorganic carbon (SIC) pools were higher in areas that were excluded from grazing. After 7 years of grazer exclusion, the total C pool in the plantÁsoil system was 10% greater (primarily due to 21% greater in SIC) than that in the area that had been grazed over that time period.

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“…Only the data for the last 120 sec were used to calculate SCE as Eq. (1) (Jasoni et al, 2005;Chen et al, 2009):…”

Section: Measurement Of Sce and Soil Temperature And Moisturementioning

confidence: 99%

Response of soil CO2 efflux to precipitation manipulation in a semiarid grassland

Wei

Zhang

Liu

et al. 2016

Journal of Environmental Sciences

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Soil CO 2 efflux (SCE) is an important component of ecosystem CO 2 exchange and is largely temperature and moisture dependent, providing feedback between C cycling and the climate system. We used a precipitation manipulation experiment to examine the effects of precipitation treatment on SCE and its dependences on soil temperature and moisture in a semiarid grassland. Precipitation manipulation included ambient precipitation, decreased precipitation (− 43%), or increased precipitation (+ 17%). The SCE was measured from July 2013 to December 2014, and CO 2 emission during the experimental period was assessed.The response curves of SCE to soil temperature and moisture were analyzed to determine whether the dependence of SCE on soil temperature or moisture varied with precipitation manipulation. The SCE significantly varied seasonally but was not affected by precipitation treatments regardless of season. Increasing precipitation resulted in an upward shift of SCE-temperature response curves and rightward shift of SCE-moisture response curves, while decreasing precipitation resulted in opposite shifts of such response curves. These shifts in the SCE response curves suggested that increasing precipitation strengthened the dependence of SCE on temperature or moisture, and decreasing precipitation weakened such dependences. Such shifts affected the predictions in soil CO 2 emissions for different precipitation treatments. When considering such shifts, decreasing or increasing precipitation resulted in 43 or 75% less change, respectively, in CO 2 emission compared with changes in emissions predicted without considering such shifts. Furthermore, the effects of shifts in SCE response curves on CO 2 emission prediction were greater during the growing than the non-growing season.

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Net ecosystem CO₂ exchange in Mojave Desert shrublands during the eighth year of exposure to elevated CO₂

Cited by 132 publications

References 24 publications

Effects of Elevated Co2 on Root Function and Soil Respiration in a Mojave Desert Ecosystem

Effects of Elevated Co2 on Root Function and Soil Respiration in a Mojave Desert Ecosystem

Grazing exclusion alters ecosystem carbon pools in Alxa desert steppe

Response of soil CO2 efflux to precipitation manipulation in a semiarid grassland

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Net ecosystem CO2 exchange in Mojave Desert shrublands during the eighth year of exposure to elevated CO2

Cited by 132 publications

References 24 publications

Effects of Elevated Co2 on Root Function and Soil Respiration in a Mojave Desert Ecosystem

Effects of Elevated Co2 on Root Function and Soil Respiration in a Mojave Desert Ecosystem

Grazing exclusion alters ecosystem carbon pools in Alxa desert steppe

Response of soil CO2 efflux to precipitation manipulation in a semiarid grassland

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Net ecosystem CO₂ exchange in Mojave Desert shrublands during the eighth year of exposure to elevated CO₂