Plant–soil relationships of the invasive annual grass Taeniatherum caput-medusae: a reciprocal transplant experiment

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).…”

Resource heterogeneity and persistence of exotic annuals in long-ungrazed Mediterranean-climate woodlands

“…This suite of fast-growing annual grasses and forbs threatens native ecological communities in the USA (Huenneke et al 1990;Seabloom et al 2003;Blank and Sforza 2007;Chambers et al 2007), southern Australia (Prober et al 2002b;Lenz et al 2003;Standish et al 2006), Africa (Vlok 1988), Europe and South America (Groves and Di Castri 1991;Gaertner et al 2009). In regions with a Mediterranean climate they form a prominent component of the exotic flora, for example in Western Australia, 45% of the 1,098 naturalized exotic species are annuals.…”

“…In other cases exotic annuals persist (Prober et al 2005;Standish et al 2006Standish et al , 2007aSmallbone et al 2007;Briggs et al 2008), suggesting they are superior competitors compared with native species (especially in the absence of their natural enemies Keane and Crawley 2002), or that underlying ecological processes have changed (Keane and Crawley 2002;Seabloom et al 2003;Blank and Sforza 2007). Increasingly, the latter hypothesis has been supported, and ecological differences between invaded and non-invaded communities have been associated with factors such as altered propagule availability and/or persistent differences in resource levels (Seabloom et al 2003;Blank and Sforza 2007;Prober et al 2002bStandish et al 2006Standish et al , 2007a. These differences have pointed to promising 'bottom-up' approaches to ecological restoration, that aim to address altered conditions and restore ecological resistance to weed invasion (D'Antonio and Chambers 2006;).…”

Mediterranean annual grasses in western North America: kids in a candy store

“…Smith et al (1994) found that undisturbed sagebrush-steppe plant communities, with diverse herbaceous, woody, and microbial components, have very conservative nutrient cycles with very little net nitrogen mineralization. It follows that relatively high concentrations of mineral nutrients observed by Blank and Sforza (2007) and others signify a shift from conservative to leaky nutrient cycling. Recent research by Davies et al (2007) supports this notion by showing that maintaining high plant functional diversity decreases soil nutrient concentrations in semiarid bunchgrass-dominated plant communities, and that removal of individual functional groups increases mineral nitrogen concentrations.…”

“…In this issue of Plant and Soil, Blank and Sforza (2007) contribute to understanding of how exotic annual grasses invade ecosystems in the western United States. Their findings, that medusahead wildrye (Taeniatherum caput-medusae [L.] Nevski) was most productive on non-invaded US soil and that plants from US-derived seeds may have evolved to utilize higher nutrient concentrations, parallel other results that suggest soils of vulnerable western US ecosystems are functionally different (i.e., more available-nutrient rich) than soils where these weeds are native and noninvasive (Blumenthal 2005;Davis et al 2000).…”