Replanting agricultural landscapes: how well do plants survive after habitat restoration?

Landscape-scale habitat restoration has the potential to return ecosystem functions and services and mitigate the loss of native flora and fauna. However, restoration projects rarely monitor the effectiveness of restoration efforts, such as quantifying the establishment success (survival) of the planted species. We monitored a landscape-scale revegetation program in south-eastern Australia that planted 5 million plants representing 35 native species over a 4-year period (2012-2015). We assessed the restoration effectiveness across years to evaluate how different lifeforms survived over time and the factors that influenced the differential survival of lifeforms and individual plant species 3 months (spring) and 9 months (after summer) post-planting. Establishment success varied across years with survival lowest in the 2015 planting season. Survival of different lifeforms after summer were associated with site-level variables (e.g. mean maximum temperature, rainfall, and soil type) with survival generally declining due to high temperatures, low rainfall, and for species planted on sandy or saline soils. Maximum temperature, rainfall, and soil type were the most important predictors of compositional change in the 20 species commonly planted across years, with two saltbush species (Atriplex paludosa) and one eucalypt species (Eucalyptus fasciculosa) having the highest survival, while one sedge species (Juncus kraussii) and two grass species (Poa poiformisandPuccinellia stricta) had among the lowest observed survival. These results highlight the importance of monitoring establishment success through survival to detect changes in the composition of lifeforms and species to guide future re-plantings aimed at returning the desired plant diversity.