Identifying Sustainable Grassland Management Approaches in Response to the Invasive Legume Lespedeza cuneata: A Functional Group Approach

Erin M Garrett,David J Gibson

doi:10.3390/su12155951

Abstract

We propose combining the filter framework model of community assembly with the passenger-driver model of non-native species behavior to help clarify the impacts of invasive species in the communities they invade and to guide sustainable management protocols. Observational field surveys and a greenhouse experiment explored the role of the invasive legume Lespedeza cuneata in the communities it invades and how natives in three functional groups—grasses, forbs, and legumes—respond to its presence. Within-site analyses from the field survey revealed differences in invaded and uninvaded areas in half of the sites, suggesting that site-specific characteristics influences whether L. cuneata’s presence corresponds to local differences in species composition. The greenhouse experiment found higher levels of saprophytic and arbuscular mycorrhizal fungi in soil conditioned by L. cuneata than in unconditioned soil. However, competition between L. cuneata or the native congener L. capitata and nine native species illustrated stronger aboveground competitive effects than belowground soil effects due to soil conditioning, with impacts differing among functional groups. The response of L. cuneata was reduced in the presence of grasses and other legumes but not forbs. Assessing the impact of L. cuneata with the combined community assembly model revealed this invasive plant acts as a driver because it alters abiotic and biotic filters to impact species composition. Managing for high grass abundance and planting native legumes will help sustain grasslands from L. cuneata invasion.

Highlights

Studies of non-native invasive species dynamics need to include invasive impacts on community assembly, especially when the control of the invasive species through management cannot keep pace with its spread
Legume growth was only slightly reduced under competition with L. cuneata, while among the functional groups, legumes suppressed the growth of L. cuneata to the greatest degree in the majority of traits. Because these results suggest that competition between grasses/legumes and L. cuneata results in the facilitation of native grasses [91], limiting similarity of other legumes, and detrimental effects to L. cuneata, these functional groups act in order to filter the establishment of L. cuneata
Lespedeza cuneata acts as a driver in the ecosystems it invades by altering the abiotic and biotic filters to affect native species on a functional group basis, providing support for a combined filter-driver framework as a useful tool for studying invasive impacts (Figure 1)

Summary

Introduction

Studies of non-native invasive species dynamics need to include invasive impacts on community assembly, especially when the control of the invasive species through management cannot keep pace with its spread. A relevant model of community assembly for studying plant invasions is the filter framework model, in which biotic and abiotic filters determine the species composition of an ecosystem by only allowing species able to “pass through” the filters to establish and thrive [1,2,3,4,5]. The passenger-driver model of community assembly differentiates between two types of non-native species: drivers, which are able to establish and dominate in an ecosystem, and passengers, which establish themselves but do not adversely affect other species [6,7]. We propose to integrdWaitseetupdrrrboiavpneocrseeasntobduinpt taaersgesreanntoegtdecrraistvapelreycsatinesdsodpf aymsnsaaejomnrgicechrsasinpngetoceisethsinedeyficnlotaesmyr sfitcresamminebtowiotdohirevkfei(rlFtseiitrgyfuroraremf1ue)wn. cIotnrioktnh(Fi[si7ga,1ud1ra,e1p21t])a.. tion, non-nIanttihvies apdaaspsteantigoenr, naonnd-ndartiivveepr asspseencigeesr abnodthdrpivaesrsstphercoieusgbhotthhpeafisslttehrrsouagnhdthesetfailbtelirsshanadt ewsthaibclhishpoint passenatgwerhsicehxipstoiinnttphaescseonmgmersuenxitisyt winitthhemcoinmimmaulnbitryowaditehrmiminpimacatls,bwrohadileerdimrivpearcstsa, lwtehriltehderfiivlteerrssa, lttherereby affectitnhge ftihlteress, tahberliesbhymafefnecttainngdthsue revstiavballisohfmoetnhtearnsdpseucrievsiv. aHl oofwoethveerr,spaecchieasl.lHenogweetvoeru, nadcherasllteanngdeitnog the role ouf nadneirnstvaansdiivneg stpheecireosleanodf iatns binrovasdiveer esffpecitessthaantdwitisll barllooawderfoerftfhecetsdethvaetlowpimll eanlltoowf sfuorsttahine able manadgeevmeleonptmpernottofcosulsstiasindaebtleermainianggemtheentmperocthoacnolissmis sdethterromuignhinwg thhiechmietcahffaneicstms sththersoeufiglhtewrshi[c1h3]it. affects these filters [13]

Objectives

Methods

Results

Conclusion