| Abstract: | The encroachment of woody plants into grasslands, woodland, and savanna has increased markedly over the past century, prompting the use of different physical methods to remove woody plants and restore grasses. Roller‐chopping is used extensively in the Americas, but little is known about its long‐term effectiveness for restoration, and whether its effectiveness varies with the intensity of encroachment. We compared the effects of roller‐chopping, under three treatment intensities (control, single treatment, double treatment), on woody plant density, ground cover, and groundstorey plants at sites of low, moderate, and high woody plant density in a semi‐arid eastern Australian woodland over 10 years. Both single and double treatment significantly altered the size distribution of Dodonaea viscosa, which comprised more than 85% of woody plants at all sites. Thus, roller‐chopping changed the size distribution of the community from an even‐size distribution to one dominated by shorter plants, irrespective of initial encroachment level. The effectiveness of roller‐chopping was strongly site‐specific, with significant reductions in density at low‐ and high‐density sites, but no clear trend in relation to the intensity of treatment (i.e. single cf. double treatment). The effectiveness of roller‐chopping was unsustained over the long term, with the suppressive effect on woody density diminishing over time. Grass cover increased with increasing intensity of woody removal, but only at the low‐density site and with some ill‐defined, variable, and short‐term effects on plant composition. Managers should consider that the short‐term effects may not adequately reflect the long‐term results of woody plant removal using the roller‐chopper. |
