Vegetation and seed bank dynamics highlight the importance of post-restoration management in sown grasslands

Abstract

Sowing grass seeds generally supports the rapid development of a closed perennial vegetation, which makes the method universally suitable for fast and effective landscape-scale restoration of grasslands. However, sustaining the recovered grasslands, and increasing their diversity is a challenging task. Understanding the role of seed bank compositional changes and vegetation dynamics contributes to designating management regimes that support the establishment of target species and suppress weeds. Our aim was to reveal the effect of post-restoration management on the vegetation and seed bank dynamics in grasslands restored in one of the largest European landscape-scale restoration projects. Eight years after restoration we sampled the vegetation and seed bank in a total of 96 plots located in 12 recovered grasslands in the Great Hungarian Plain. In each recovered grassland stand we designated a mown (mown from Year 1 to Year 8) and an abandoned sample site (mown from Year 1 to Year 3 then abandoned from Year 4 to Year 8). Mown and abandoned sites showed divergent vegetation and seed bank development. Abandonment led to the decline of sown grasses and higher cover of weeds, especially in the alkaline grasslands. Our study confirmed that seed bank has a limited contribution to the maintenance of biodiversity in both grassland types. We found that five years of abandonment had a larger effect on the seed bank than on the vegetation. We stress that long-term management is crucial for controlling the emergence of the weeds from their dense seed bank in restored grasslands.Implications for practiceSeed sowing of grass mixtures can be a feasible tool for restoring grasslands at large scales. However, the developed vegetation usually has low biodiversity and a high seed density of weeds is typical in the soil seed bank even several years after the restoration. Therefore, post-restoration management is necessary for suppressing weeds both aboveground and belowground.We recommend to design the long-term management of the sites subjected to grassland restoration already in the planning phase of the restoration projects and ensure that the management plan is ecologically and economically feasible.We recommend to complement the monitoring of vegetation with the analysis of soil seed bank for evaluating restoration success.

Diversity and Variation of Asymbiotic Nitrogen-Fixing Microorganisms in Alpine Grasslands on the Tibetan Plateau

“…In addition, miscellaneous grasses increased the number of OTU species (Figure 4). In agreement with these results, Valkó et al (2020) reported that the planting of gramineous grasses was beneficial to the growth of perennials. This could have occurred by effectively changing the community structure of soil microorganisms (Zhu et al, 2020) and by promoting various species of rhizosphere ANF microbial populations (Minamisawa et al, 2004;Miyamoto et al, 2004;Zhang et al, 2008).…”

Long-term active restoration of degraded grasslands enhances vegetation resilience by altering the soil seed bank

“…Deferred grazing from spring to autumn and rotational grazing increased the soil seed bank of perennial and annual grasses (Nie et al 2015). However, soil seed banks made limited contributions to the maintenance of plant biodiversity in both mown and abandoned sites on the Great Hungarian Plain (Valko et al 2020).…”