Plant recruitment and survival as indicators of ecological restoration success in abandoned pasture land in Nurcoung, Victoria, Australia

摘要

Introduction One of the major impediments to developing better restoration strategies is the inadequate documentation of past restoration efforts. In 2008, Greening Australia commenced ecological restoration on the Nurcoung property in Victoria to enhance local biodiversity, and in this paper we report on the habitat restoration outcomes in the three Ecological Vegetation Classes (EVC) found on this property. Methods Permanent sample plots (12?×?20?m) were randomly established in July 2010 in each of the restoration areas, with 9, 10, and 24 plots demarcated in Shallow Sands Woodland (SSW), Heathy Woodland (HW), and Sandstone Ridge Woodlands (SRW), respectively. Individual plots were prepared to include three seeded rows. Plots were assessed for seedling recruitment and survival in May 2010, April 2011, and May 2012. Records of individual seedling development included their height and cover, and their location within the plot. Results Our study shows that interaction between the age of the planted and direct-seeded vegetation and the nature of the EVC significantly affects the composition of plants and the soil surface in that species and, further, that soil cover parameters develop in different ways in the different experimental plots. A SIMPER analysis of soil cover parameters shows that most of the variation over the years of restoration is attributable to differences in the amount of bare soil recorded, rather than the amount of leaf-litter cover, and that these changes in soil cover parameters differ between EVCs over the sampling periods. The direct-seeding study shows that whilst most of the broadcast species were recruited, some species used in the Shallow Sands Woodland, the Heathy Woodland, and the Sandstone Ridge Shrubland did not show evidence of recruitment during the three sampling periods. Although the density of most seedlings increased in subsequent sampling years, the planted species Callitris gracilis, Callitris rhomboidea, Hakea muelleriana , and Melaleuca lanceolata did not survive. Conclusions As a result of the land use change, new assemblages of abiotic and biotic system components appear to lead to the development of stable alternative ecological states. These ‘novel’ ecosystems now play an important part of the natural resource base, requiring careful characterization to better understand current development trajectories and future states, and to inform management strategies to meet desired restoration outcomes. Although the study sites have been abandoned for a long time, broadcast seeds and plant seedlings show they can overcome internal resilience.