Canadian Forest Service Publications
Different root and shoot responses to mowing and fertility in native and invaded grassland. 2014. Balogianni, V.G.; Wilson, S.D.; Vaness, B.M.; MacDougall, A.S.; Pinno, B.D. Rangeland Ecology and Management 67(1):39-45.
Issued by: Northern Forestry Centre
Catalog ID: 35390
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Grassland root responses to mowing and fertility are less well known than shoot responses, even though as much as 90% of productivity in semiarid grasslands occurs belowground. Thus, understanding root responses may aid the management of invasive grassland species such as Agropyron cristatum (L.) Gaerth (crested wheatgrass). We asked whether root responses reflect shoot responses to mowing and fertility in native grassland with and without a major component of crested wheatgrass. We subjected grasslands in northern Montana to 5 yr of mowing at two nitrogen (N) levels and followed root responses with minirhizotrons. Surprisingly, the roots of both native and invaded grasslands were unaffected by mowing and N addition, despite significant changes in shoot mass across both vegetation types. Root length was significantly greater beneath areas heavily occupied by crested wheatgrass (363 m·m-2 image ± 200, mean ± standard deviation [SD]) than areas comprising largely native grassland (168 m·m-2 image ± 128 SD). Also, no interactions occurred between year and any other factor, indicating that there were no changes in belowground responses over the 5 yr examined. In contrast, shoot mass was significantly reduced by mowing (not mowed, 612 g·m-2 ± 235 SD; mowed, 239 g·m-2 ±81 SD) and was significantly increased by N addition (no added N, 380 g·m-2 ± 215 SD; added N, 488 g·m-2 ± 287 SD). In conclusion, 5 yr of mowing decreased shoot mass, but not root mass. On the other hand, 5 yr of N addition increased shoot mass, but not root mass. Given that most production and competition in grasslands occurs belowground, this suggests that mowing may not be a successful tool for reducing crested wheatgrass root length, regardless of soil fertility.
Plain Language Summary
Grassland root responses to mowing and fertilization are less well-known than shoot responses, even though as much as 90% of total plant productivity in semiarid grasslands occurs belowground. Understanding root responses may aid in the management of invasive grassland species and ecosystem restoration. We asked whether root responses reflect shoot responses to mowing and fertilization in crested wheatgrass. For 5 years, we fertilized (at 2 nitrogen levels) and mowed grasslands and monitored root responses. We found that mowing and fertilization had no effect on roots in either native or invaded grasslands, suggesting that these ecosystem restoration tools may not be effective for managing invasive species.