23 research outputs found
Nutrient loaded seedlings reduce the need for field fertilization and vegetation management on boreal forest reclamation sites
Fine Root Dynamics of Trembling Aspen in Boreal Forest and Aspen Parkland in Central Canada
Fine roots constitute a relatively small component of ecosystem carbon pools but they are vitally important in carbon and nutrient cycles because of their role in water and nutrient uptake and high turnover rates. The objective of this study was to compare trembling aspen fine root (\u3c2mm) dynamics, including standing crop, productivity, and turnover rates, between two forest regions. Sites were located in boreal forest near Prince Albert in central Saskatchewan and 500 km south in aspen parkland near Regina. The parkland site is a proxy for the expected future climate of the boreal site. Mini-rhizotrons were established in mature trembling aspen stands at both sites to a depth of 40 cm and were monitored throughout the 2004 growing season. The parkland site had significantly greater fine root biomass (23.2 vs 5.4 Mg/ha, p=0.018) and root length productivity (234.9 vs 29.8 m/m2 image/year, p=0.004) than the boreal site. Fine roots in the parkland site also made up a larger component of total tree biomass than in the boreal site and accounted for a larger percentage of the total net biomass production (50% vs 38%). Root size distribution differed between sites with the parkland site having significantly more standing crop and yearly production of the smallest root sizes (\u3c0.2 mm). Fine root length turnover was similar between sites (41 vs 49 %/year, p=0.385). This study indicates that there are significant differences in trembling aspen fine root dynamics between these forest regions which raise questions about future C cycling and tree productivity in the boreal forest depending on how the fine roots respond to the future climate
Maximizing Natural Trembling Aspen Seedling Establishment on a Reclaimed Boreal Oil Sands Site
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Different root and shoot responses to mowing and fertility in native and invaded grassland
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. © 2014 The Society for Range Management.The Rangeland Ecology & Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information