Contrasting effects of land use legacies on grassland restoration in burnt pine plantations

Abstract

Legacies of previous land use may affect ecosystem recovery after the specific land use has ceased. Determining which legacies do limit ecosystem recovery is critical to perform effective ecological restoration. Pine (Pinus spp.) plantations have replaced various natural habitats including woodlands, shrublands and grasslands worldwide. Following pine tree removal, the restoration of these habitats may be complicated by pine plantation legacies. In this study, we tested three factors that may constrain grassland recovery in a former pine plantation following burning in an inland sand dune region in Hungary. We evaluated the effects of pine litter removal, native grass seeding and the presence of invasive Asclepias syriaca on vegetation composition during seven years of recovery using generalised linear mixed effect models and non-metric multidimensional scaling. We found that litter removal did not facilitate grassland regeneration. Grass seeding led to a fast recovery of grass cover, but negatively affected the abundance of unseeded target species. The presence of Asclepias had only transient effects on seeded grasses but positively affected unseeded target species richness. We conclude that sand grasslands have high restoration potential in burnt pine plantations despite the presence of several land use legacies. We found no evidence that pine litter or the presence of Asclepias would negatively influence grassland recovery, which implies that their removal is not necessary for a successful restoration. We suggest that moderate seeding densities of native grasses need to be applied to avoid the suppression of other target species.

Barriers to ecosystem restoration presented by soil legacy effects of invasive alien N2‐fixing woody species: implications for ecological restoration

“…Secondary invaders and weedy native species that establish can be manually weeded, mowed, selectively grazed (Maron & Jefferies ; Gooden et al ; Milchunas et al ), or controlled through herbicide or graminicide application (Szitár et al ). For example, mowing followed by biomass removal during restoration of coastal prairie grasslands reduced the abundance of secondary invaders (Maron & Jefferies ).…”

“…For example, seeding with native species during restoration of coastal sandplain grassland in the United States increased native species diversity (Neill et al ). There is need for careful planning and clearly defined restoration goals before conducting native species reintroduction (Honnay et al ; Szitár et al ). For example, some restoration programs might focus on rehabilitation of functional groups or clusters of focal species, whereas others might focus on particular endangered species (Palmer et al ).…”

Invasive Asclepias syriaca can have facilitative effects on native grass establishment in a water‐stressed ecosystem

“…In the same study site, Szitár et al. () conducted a grass seeding experiment where they did not find any difference in seeded grass cover between plots previously invaded and uninvaded by Asclepias 6 years after seed sowing. However, in the above studies, the abundance of Asclepias was not set experimentally, thus causal conclusions for its impact could not be drawn.…”

“…(), changing the character, form, condition and nature of ecosystems in Hungary (Török et al., ). Nevertheless, it is a transformer invasive species and has reached high abundance in the invaded regions, only a few studies have assessed milkweed impact on native species and these arrived at different conclusions (Gallé, Erdélyi, Szpisjak, Tölgyesi, & Maák, ; Kelemen et al., ; Somogyi, Lőrinczi, G., Kovács, J., & Maák, ; Szitár et al., , ).…”

“…The dominance of correlational studies and their contrasting results call for further research to elucidate the effects of Asclepias on the regeneration and persistence of native vegetation. This would also have great practical importance for the management of Asclepias because mowing and chemical control, the two widely used control methods, can have low efficacy and large non‐target impact under some special abiotic and biotic circumstances (Szitár et al., , ).…”