Rubus laciniatus , cutleaf blackberry

This Species Review summarizes the scientific information about fire effects and relevant ecology of cutleaf blackberry in North America that was available as of 2020. Cutleaf blackberry occurs in western and eastern North America. It is invasive in the Pacific Northwest—particularly coastal Washington—although it is not as invasive as Himalayan blackberry. Cutleaf blackberry grows in cool temperate and semiarid climates and is both a facultative wetland and an upland species. It is most common at low elevations, on disturbed, moist to mesic sites. It grows in hardwood and conifer communities; within these communities, it is most invasive in riparian areas. It may also be invasive in riparian shrublands. Cutleaf blackberry reproduces primarily vegetatively via layering and sprouting from its rhizomes and root crown. It also reproduces from seed, which helps it establish on new sites, including burns. Its seeds are primarily dispersed by animals. The seeds have a hard coat, are dormant upon dispersal, and stored in the soil seed bank. Fire or animal ingestion helps break seed dormancy. Cutleaf blackberry is primarily an early-successional species that prefers open, disturbed sites such as streambanks, burns, clearcuts, and recently thinned or logged areas. As of 2020, fire effects on cutleaf blackberry were not documented in the literature, and there were few studies on its postfire response. It is likely that fire top-kills cutleaf blackberry, and that it sprouts after top-kill. Seeds buried in the soil seed bank are probably protected from fire. Cutleaf blackberry occurs on new burns, although its method of regeneration (from sprouts and/or seeds) is not documented. A study in the Willamette Valley of Oregon suggests that in the short term, combined density of cutleaf blackberry and Himalayan blackberry increases after one or two consecutive annual prescribed fires. The study did not distinguish between the two blackberry species. A study in Sierran mixed-conifer forests found no effect of either mastication alone, or mastication followed by prescribed fire, on basal area of cutleaf blackberry. Where cutleaf blackberry is invasive, it displaces native riparian shrubs by overtopping and outcompeting them for space, light, and nutrients. It may be controlled using a combination of treatments over many years. These may include prescribed fire, mechanical treatments, grazing, and/or herbicides. However, few studies had examined the effects of control treatments on cutleaf blackberry.