Soil conditioning affects interactions between native and invasive exotic perennials of semi‐natural grasslands

Abstract

Summary Semi‐natural perennial grasslands are of increasing importance as components of multifunctional agroecosystems, combining biomass production with provision of other ecosystem services. Soil legacies from previous land use or exotic species can hinder their establishment, but might be overcome through a multi‐stage successional strategy, whereby certain species are used to facilitate native grassland species establishment. We tested this strategy via a feedback experiment examining soil‐conditioning effects on interference interactions between native and exotic species. Soils in a former maize–soybean production field in Minnesota, USA, were conditioned for 3 years with native or invasive exotic perennials or a maize–soybean crop rotation. Nitrogen (N) fertilization was an additional treatment in field plots. In a greenhouse, native and invasive exotic perennial grassland seedlings were grown on these soils, in monoculture and in native–exotic species pairs, with and without N fertilization. The impact of soil conditioning and field and greenhouse N fertilization on interactions between native and exotic seedlings in mixture was determined. Neighbouring plants suppressed biomass production in all native and exotic species. The maize–soybean rotation left a soil legacy that enhanced suppression of native species when grown with exotic species, while exotic species suffered no such disadvantage. The strong and specific disadvantage to native species of maize–soybean soils decreased with greenhouse N fertilization, but remained significant, while field N addition did not alter this effect. Synthesis and applications. We found that the negative soil legacy of the maize–soybean rotation for native plant performance in interaction with exotics was greatly diminished in soils conditioned by native or exotic perennial species, irrespective of nitrogen addition. This highlights the potential value of perennial species in conversion from row‐crop agriculture to grasslands, because all perennial species alleviated the enhanced suppression of natives observed on maize–soybean soils. We did not find strong evidence that these perennial species were capable of specifically facilitating native species over exotics, but a broader range of species should be evaluated.

Conservation of species-rich subtropical grasslands: traditional management vs. legal conservation requirements in primary and secondary grasslands

“…For the study region, reestablishment of grasslands after other land uses seems possible, but these secondary grasslands differ from primary grasslands in terms of composition and structure (Koch et al 2016;Torchelsen et al 2018). In general, secondary grasslands on sites with former agricultural use are characterized by nutrient concentrations in the soil that differ from those of primary grasslands, promoting changes in vegetation development (Céspedes-Payret et al 2012;Andrade et al 2015;Vink et al 2016). In our case, secondary grasslands showed lower total species richness and a species composition that differed from that of traditionally managed grasslands.…”

Plant community recovery following Sericea lespedeza (Lespedeza cuneata) removal: testing for a soil legacy effect

“…The importance of site‐specific effects has been well‐documented (e.g. Eviner & Hawkes ; Millikin et al ; Vink et al ) and is reflected in the variable responses found in PSF and legacy literature (Ehrenfeld ; Vilà et al ). Within our own experiment, historical disturbance and fertilization treatments had a significant effect on species cover data 5–6 years after cessation.…”

An exotic plant successfully invaded as a passenger driven by light availability

“…increasing richness and aboveground biomass) by P. kansuensis invasion. Neutral values indicate that the invasion of P. kansuensis has little effect on the native community ( Vink et al., 2017 ). In order to better quantify these impact categories, we divide RII values into three intervals as follows: RII values greater than 0.05 were regarded as positive; RII values less than -0.05 were regarded as negative; RII values between -0.05 and 0.05 were considered as neutral ( Armas et al., 2004 ).…”