Seeding, mowing and carbon amendment in old-field restoration
Cropland abandonment is an opportunity for semi-natural biodiverse ecosystems to develop through spontaneous succession or active restoration. Spontaneous recovery is limited by the dispersal and capacity of species to establish under the given environmental circumstances.
The aim of the study was to manipulate the dispersal, abiotic and biotic filters separately and in combinations in order to restore the endemic Pannonian sand grassland on abandoned fields. Treatments included seeding of five species characteristic to the target grassland, carbon amendment to reduce excess nitrogen caused by cultivation and mowing with subsequent hay removal in 1 m by 1 m plots in three old-fields from 2003 to 2008.
Seeding was the most important treatment increasing species richness, vascular cover and enhancing target species composition. Mowing played a secondary role, acting primarily in interaction with the other treatments. Carbon amendment significantly reduced soil mineral nitrogen, but played a subordinate role in determining vegetation composition. Significant interactions were found between the biotic and dispersal and the biotic and abiotic filters determining primarily the structural characteristics of the vegetation in terms of vascular cover, moss cover, litter and bare ground. Regarding species composition, synergistic links between the dispersal and biotic filters for seeded species and long-lived forbs, and antagonistic interaction between the dispersal and abiotic filters for seeded species were found.
Dispersal limitation proved to be the most important barrier to rapid vegetation development in the short term. The spread of seeded species into non-seeded plots on the long term did not allow for the causal analysis of single factors such as mowing or carbon addition in the long term, but it has optimised the restoration process. Based on our results we suggest that restoration of old fields can be triggered with the use of small seed introduction units, also referred to as "establishment windows".
Llumiquinga, Y.B., Reis, B.P., Sáradi, N., Török, K., Szitár, K., Halassy, M., (2021): Long-term results of initial seeding, mowing and carbon amendment on the restoration of Pannonian sand grassland on old fields. Tuexenia 41: 361-379.
Halassy, M., Botta-Dukát Z., Csecserits, A., Szitár, K. (2019): Trait based approach confirms the importance of propagule limitation and assembly rules in old‐field restoration. Restoration ecology 27(4): pp. 840-849.
Halassy, M, Singh, A.N., Szabó, R., Szili-Kovács, T., Szitár, K., Török K. (2016): The application of a filter-based assembly model to develop best practices for Pannonian sand grassland restoration. Journal of Applied Ecology, 53: 765-773.