Imperata cylindrica, an alien invasive grass, maintains control over nitrogen availability in an establishing pine forest

Abstract

In a field experiment in Florida, USA, 15 Nlabeled Ammonium Sulfate was used to compare how Pinus taeda seedlings take up and use N in the presence of I. cylindrica and native vegetation using three treatments: 1) vegetation free 2) native competition, and 3) I. cylindrica competition. Imperata cylindrica competition led to smaller pine seedlings with significantly less N content in the pine foliage and roots than those in the native treatment. Competition from I. cylindrica for N contributed to the pine seedlings taking up a greater percentage of the applied fertilizer than the seedlings competing with native vegetation; however, because of their reduced growth they were less efficient in utilizing the fertilizer N. The belowground biomass of I. cylindrica on average was seven times higher than the native species. Despite its lower N concentration in foliage and roots, it retained significantly more N per hectare compared to the native vegetation. While the native species retained more N aboveground, I. cylindrica held significantly more belowground, thus invasion by this grass would lead to a shift of N pools from above to belowground. The fact that we were able to account for 81.5% of the applied fertilizer in the I. cylindrica treatment compared to 62.2% in the native treatment suggests that I. cylindrica tightly retains most of the available N on site making it a particularly good invader.

Simple plant traits explain functional group diversity decline in novel grassland communities of Texas

“…The C:N ratio, which was consistently higher in native than exotic C 3 species, was the most consistent trait across species and functional groups in explaining C 3 plant success in native mixtures, perhaps a reflection of greater resource use efficiency, a slower potential rate of return on investments in leaves and longer leaf lifetimes (Wright et al 2004). Several other studies have compared exotics to natives in their efficiency to utilize resources (Smith and Knapp 2001;Drenovsky et al 2008;Feng and Fu 2008;Daneshgar and Jose 2009;Han et al 2012). Funk and Vitousek (2007) suggested that greater photosynthetic nutrient use efficiency is a functional trait that enhances exotics competitive ability allowing them to invade nutrient poor systems in Hawaii.…”

Invasion success of cogongrass, an alien C4 perennial grass, in the southeastern United States: exploration of the ecological basis

“…3 Decreased pH in areas infested with cogongrass compared to native vegetation in an abandoned agricultural field in northwestern Florida (Holzmueller and Jose, unpublished data) for light, water, and nutrients. When compared to native species in these ecosystems, cogongrass has effectively shown that it is a superior competitor for light (Ramsey et al 2003), water, and nutrients (Daneshgar and Jose 2009a).…”

“…Where found, cogongrass can form stands of up to 10,000 ha and these stands are typically low in plant species diversity (Holm et al 1977). Upon invading a new community, cogongrass has been documented to form large stands that could reduce forest productivity (Daneshgar et al 2008), alter nutrient availability (Daneshgar and Jose 2009a), and decrease native species biodiversity (Collins et al 2007).…”

The invasive alien plants threatened the balance of ecosystem in conservative area in Ontoloe Island, Flores-Indonesia

“…The increase of the I. cylindrica has involved the ecology because this species has the power in killing other plants and resistant to the fire [39]. The changes of nutrient cycle caused by exotic plants will harm seedling in forest regeneration [40] because I. cylindrica can allocated the carbon of soil, and growth rapidly after the wildfire. Large rhizome of I. cylindrica not only results in fast regeneration of leaves, but also produce the exudate allelopathic root which can inhibit the germination and other plants growing [41].…”