Vegetation restoration of secondary bare saline-alkali patches in the Songnen plain, China

Questions: What factors limit vegetation restorationof secondary bare saline-alkaline patches (BSAP) inthe Songnen grassland of northeast China? Is thereany adaptive approach to promote revegetation inthe shortest time possible and at a low cost?Location: Northeast China.Methods: Considering the climate, soil saline-alkali-zation and available seed sources, a new approachwas adopted to restore vegetation in BSAP, whichwere formed by the degradation of typical Leymuschinensis grasslands owing to long-term overgrazing.The experimental treatments included no treatment(CK), fencing (F), fencing1inserting cornstalks (FS),fencing1inserting cornstalks1sowing L. chinensis(FSL) and fencing1inserting cornstalks1sowingPuccinellia chinampoensis (FSP). The assumptionsbehind inserting cornstalks were not only that theywould create safe sites for initial revegetation but alsothat they would enhance seed input by trapping andcontaining the seeds from seed movement on theBSAP surface.Results:Seedbankshortagewasanimportantfactorlimiting initial revegetation in BSAP; seed move-ment on the BSAP surface could provide thenecessary seed source if it were contained by effec-tive measures. Vegetation at the sites FS, FSL andFSP was restored well in terms of the above-groundbiomass and coverage. Inserted cornstalks actedas safe sites that enhanced the plant survival ratein BSAP; they also enhanced the ability to containseed movement, thus providing a seed source forinitial revegetation. Along with initial revegetation,tussocks around cornstalks can provide better safesites, which in turn can accelerate subsequent vege-tation restoration in BSAP.Conclusions: Theapproachentailsthestrategicuse ofdiverse seed sources and the construction of safe siteswithagriculturalbyproducts(cornstalks);therefore,itisalow-costmethodandcanbeusedonawidespreadscale.TheresultsprovidevigoroussupportinfavorofvegetationrestorationinBSAPandseverelydegradedgrasslands in the region. In practice, this approachcan be used in degraded ecosystems with compactedsoil surfaces (including arid and salt-affected soils) topromote revegetation in various regions.Keywords: Grassland; Restoration; Safe site; Saline-alkaline patches; Seed bank; Seed movement.Abbreviations:BSAP5baresaline–alkalinepatches;CK5control; F5fencing; FS5fencing1insertingcornstalks; FSL5fencing1inserting cornstalks1sowing L. chinensis; FSP5fencing1inserting corn-stalks1sowing P. chinampoensis.