Enhancing plant diversity in a novel grassland using seed addition

Abstract

Abstract1. Restoration of novel ecosystems to a historical benchmark may not always be possible or advisable. Novel ecosystems may be managed by targeting specific components and accepting the novelty of other ecosystem attributes. The feasibility of this component-wise management of novel ecosystems has rarely been tested.2. In a novel grassland, where C 3 grasses have replaced C 4 grasses, nutrients have been elevated, and diversity has been lost due to a history of agricultural land use, we aimed to return diversity using seed addition, without altering the dominant grass matrix or nutrient status. Using direct seeding, with and without soil disturbance, we assessed the ability of 10 species of native forbs to establish.3. Eight of the 10 seeded species established in the first year. Soil disturbance increased establishment success by 50%, while high levels of exotic cover decreased it by 24%. Establishment was inversely related to total plant cover at sowing, with a 10% increase in initial plant cover decreasing establishment by 47%.4. By the third year, six of the eight species persisted and five were flowering. Survival and reproduction in the third year was not associated with the soil disturbance treatment or plant cover. Synthesis and applications.We show that native plant species can be re-established in grasslands where abiotic and biotic conditions are novel relative to their reference state. This suggests that the conservation value of novel ecosystems can be enhanced using simple restoration tools that target specific ecosystem components.

Quantifying Long-Term Urban Grassland Dynamics: Biotic Homogenization and Extinction Debts

“…The removal of dominant grass species allows light availability for intertussock forbs [75,76], however, in their study in Australian grasslands Johnson et al found that seed limitation of forbs was a constraint to the recovery of degraded grasslands as indigenous forb recruitment mostly relied upon seed addition [76]. This finding is also supported by Zamin et al [77]. Another management strategy that could be employed in fragmented natural areas is the collection of forb seeds from nearby natural areas and sowing it in degraded urban open spaces including along road verges and railway embankments [78].…”

Evidence for direct effects of fire‐cues on germination of some perennial forbs common in grassy ecosystems

“…This is consistent with both the timing of natural and prescribed fires in the region, which typically occur in the cooler months following summer and studies which suggest that the interplay between fire, rainfall and temperature influences forb recruitment (Morris & Gibson‐Roy ; Zamin et al . ).…”

“…Although this theory has received criticism (Keeley & Pausas ), it does seem to be supported by some data which suggests that physical disturbance can promote recruitment of forbs in the absence of fire (Zamin et al . ). Responses to smoke but not heat shock may also be symptomatic of cooler burns which often take place in late‐autumn and winter where soil temperature may not exceed those used in this study (Morgan & Williams ).…”

Multivariate drivers of diversity in temperate Australian native grasslands

“…If a grassland has a long history of grazing, it is likely that grazing-sensitive plant species have been lost from the system (Price et al 2010). Hence, reinstating fire or grazing removal is unlikely to recover those species without further management interventions such as seed addition and could lead to loss of species that require some disturbance (Kirkpatrick et al 2005;Johnson et al 2018;Zamin et al 2018). Little is known about the effects of native marsupial grazing on Australian temperate grasslands; a few studies have explored impacts of over abundant native animals, and high selectivity has been observed (Leonard et al 2010).…”