Management regime and survey timing influence restored urban meadow seedbank composition

Background/Question/Methods

The human influence on urban ecosystems can greatly affect biodiversity loss and gains through highly repetitive disturbances, including human use (e.g. recreation) and management (e.g. mowing). The restoration of meadows and grasslands in urban areas offers the opportunity to rehabilitate wildlife habitat, increase the biodiversity and productivity of formerly degraded spaces, and provide areas to connect people to nature. We investigated the impact of above-ground management regimes (i.e., tilling and mowing) within The Meadoway (www.themeadoway.ca); a 16-km green corridor beneath powerlines that includes numerous restored urban meadows developed using native plant seed mixes designed to promote aesthetic views and pollinator habitats.We monitored the spring and fall emergence of native and non-native spontaneous and native sown plant species from 81 meadow plots across 9 locations, representing three common restoration techniques utilized by conservation managers (seed tilling, maintenance mowing, and undisturbed) in urban meadow ecosystems. We removed 405 field soil core samples which were then frozen to mimic winter dormancy, and transplanted into greenhouse trays under controlled photoperiod and temperature conditions to allow for germination. We evaluated composition and abundance of forb and grasses within the seedbank in response to management regime, spatial distribution, and survey timing (Spring and Fall).

Results/Conclusions

From the greenhouse study, across all plots 96 species representing more than 14,000 germinants were recorded, representing forbs, grasses and trees. Spring and fall sampling indicate management regimes significantly affect community composition, with seed tillage significantly reducing abundance and biodiversity of the seed bank. This is in line with management goals: practitioners often to deplete seedbanks of non-native and invasive species prior to targeted seed mix dispersal. Undisturbed treatments showed the greatest variation in community composition and abundance, with the greatest proportion of rare species. Additionally, maintenance mowing did not significantly differ in abundance of species present in managed plots when compared with undisturbed plots, but showed variation in community composition and diversity. Sampling timing revealed key differences in community composition within the seedbank between seasons. For conservation managers seeking to evaluate the success of targeted sowing initiatives and species inventory efforts, timing of sampling can impact the emergence of seedlings within the seedbank.