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

Questions: What factors limit vegetation restoration of secondary bare saline‐alkaline patches (BSAP) in the Songnen grassland of northeast China? Is there any adaptive approach to promote revegetation in the shortest time possible and at a low cost? Location: Northeast China. Methods: Considering the climate, soil saline‐alkalization and available seed sources, a new approach was adopted to restore vegetation in BSAP, which were formed by the degradation of typical Leymus chinensis grasslands owing to long‐term overgrazing. The experimental treatments included no treatment (CK), fencing (F), fencing+inserting cornstalks (FS), fencing+inserting cornstalks+sowing L. chinensis (FSL) and fencing+inserting cornstalks+sowing Puccinellia chinampoensis (FSP). The assumptions behind inserting cornstalks were not only that they would create safe sites for initial revegetation but also that they would enhance seed input by trapping and containing the seeds from seed movement on the BSAP surface. Results: Seed bank shortage was an important factor limiting initial revegetation in BSAP; seed movement on the BSAP surface could provide the necessary seed source if it were contained by effective measures. Vegetation at the sites FS, FSL and FSP was restored well in terms of the above‐ground biomass and coverage. Inserted cornstalks acted as safe sites that enhanced the plant survival rate in BSAP; they also enhanced the ability to contain seed movement, thus providing a seed source for initial revegetation. Along with initial revegetation, tussocks around cornstalks can provide better safe sites, which in turn can accelerate subsequent vegetation restoration in BSAP. Conclusions: The approach entails the strategic use of diverse seed sources and the construction of safe sites with agricultural byproducts (cornstalks); therefore, it is a low‐cost method and can be used on a widespread scale. The results provide vigorous support in favor of vegetation restoration in BSAP and severely degraded grasslands in the region. In practice, this approach can be used in degraded ecosystems with compacted soil surfaces (including arid and salt‐affected soils) to promote revegetation in various regions.