Spartina alterniflora invasion increases soil inorganic nitrogen pools through interactions with tidal subsidies in the Yangtze Estuary, China

Abstract

Invasive alien plants increase both plant N and soil inorganic N pools in many terrestrial ecosystems. This is believed to be the result of altered plant-soil-microbe feedbacks that accelerate N cycling. However, it may also be due to the greater ability of invasive species to uptake lateral N subsidies that can modify ecosystem N dynamics. We conducted manipulative field experiments to determine the impact of smooth cordgrass (Spartina alterniflora) invasion on the N cycling of salt marsh ecosystems in the Yangtze Estuary, China. The results showed that the aboveground plant N and soil inorganic N pools in S. alterniflora marshes, 14.39 and 3.16 g N m(-2), were significantly higher than those in native common reed (Phragmites australis) marshes, 11.61 and 2.29 g N m(-2). These increases after invasion were explained by a significantly higher uptake of dissolved inorganic N (DIN) from tidal subsidies in S. alterniflora marshes (6.59 g N m(-2)) than from those in P. australis marshes (1.61 g N m(-2)), and not by soil organic N mineralization, which was not significantly different between S. alterniflora (6.45 g N m(-2)) and P. australis marshes (6.84 g N m(-2)) during the growing season. Our study indicated that the ecosystem engineering effects of S. alterniflora, which increases the interception of external N input, can be an alternative mechanism that increases plant N and soil inorganic N pools--especially in ecosystems with ample anthropogenic N subsidies, such as the coastal wetlands of China.

Effects of semi-lunar tidal cycling on soil CO2 and CH4 emissions: a case study in the Yangtze River estuary, China

“…6 Regression analyses of soil CO 2 emissions with soil moisture (a), Eh (b), salinity (c) and sulfate (d), within a semi-lunar tidal cycle Wetlands Ecol Manage was absorbed and utilized by plants because the wetland had high plant productivity, especially in S. alterniflora stands (Liao et al 2007). The content of soil sulfate in our study was more than ten times higher than the nitrate content reported in Peng et al (2011), so nitrate may not be a major inhibitor of methanogenesis. Several studies have demonstrated that high soil salinity and sulfate were the most important inhibitors of CH 4 production in coastal wetlands Purvaja and Ramesh 2001;Poffenbarger et al 2011).…”

“…on CH 4 production were insignificant or nonexistent in STP. Peng et al (2011) reported that tides imported inorganic nitrogen including nitrate to wetlands of the Yangtze River estuary. However, most inorganic nitrogen y = 11.50 -0.07x R 2 = 0.11, P = 0.01 y = 5.45 + 0.02x R 2 = 0.37, P < 0.0001 y = -9.05x + 14.87 R 2 = 0.24, P < 0.001 y = 12.92 -7.32x R 2 = 0.33, P < 0.0001 Fig.…”

Potassium: a neglected nutrient in global change

“…By examining the impacts of seven widespread invasive plant species in northern Europe, Dassonville et al (2008) observed that invasive species reduced soil K availability in K-rich soils, but increased soil K availability in K-poor soils. The success of alien plants thus appears to depend on high K availability in productive environments and on low K availability in less productive environments; however, the small number of studies precludes formulation of a definitive conclusion about this dependence (Funk & Vitousek, 2007;Peng et al, 2011;. Alien plants with a more efficient use of K may be able to increase their spread in arid areas.…”

The Role of Plants in the Effects of Global Change on Nutrient Availability and Stoichiometry in the Plant-Soil System

“…2). Alien invasion in nutrient-rich environments also frequently favors plant species with high rates of photosynthesis and growth (Baruch and Goldstein, 1999;Leishman et al, 2007;Feng et al, 2008;Schumacher et al, 2009;González et al, 2010;Mozdzer and Zieman, 2010;Feng et al, 2011), high reproductive outputs (González et al, 2010), large size (van Kleunen et al, 2010), low C-nutrient ratios in tissues (Monaco et al, 2003;Agrawal et al, 2005;Reed et al, 2005;Packett and Chambers, 2006;Schumacher et al, 2009;González et al, 2010;Peñuelas et al, 2010), low costs of foliar construction (Nagel and Griffin, 2001;Feng et al, 2007;González et al, 2010), large investments of N in photosynthetic production (Ehrenfeld, 2003;Xu et al, 2007;Shen et al, 2011), higher capacities of nutrient uptake (Zabinsky et al, 2002;Harrington et al, 2004;Blank and Sforza, 2007;Feng, 2008;Blank, 2010;Hewins and Hyatt, 2010;Leffler et al, 2011;Peng et al, 2011), and high levels of plasticity in the acquisition of resources as a function of pulses in nutrient availability (Leffler et al, 2011). These factors indicate that nutrient uptake and all foliar traits enabling rapid rates of growth (Zabinsky et al, 2002;Leishman et al, 2007) will help invading species to succeed when resources are not limited (Bray et al, 2003;Shah et al, 2009).…”