Canadian Forest Service Publications

Fine root response to soil resource heterogeneity differs between grassland and forest. 2013. Pinno, B.D; Wilson, S.D. Plant Ecology 214(6):821-829.

Year: 2013

Issued by: Northern Forestry Centre

Catalog ID: 34790

Language: English

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Available from the Journal's Web site.
DOI: 10.1007/s11258-013-0210-1

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Abstract Soil resource heterogeneity has clear effects on plant root development and overall plant performance. Here we test whether contrasting vegetation types have similar or different responses to soil patches of differing resource availability. We examined the fine root responses of grassland and forest vegetation at the northern edge of the Great Plains to transplanted patches of resource-poor and resourcerich soils, using rhizotron imaging. Every aspect of measured root behavior, including root length, production, mortality, turnover, variability and size distribution, varied significantly between patch types, and most aspects also varied between vegetation types. Most importantly, differential responses to patches between grassland and forest were shown by significant interactions between patch type and vegetation for two response variables. First, root length variability was significantly lower in resource-rich compared to resource-poor patches in forest but not grassland. Second, the proportion of very fine roots was significantly greater in resource-rich than resource-poor patches in forests but not grassland. Thus, compared to grassland, forest more fully occupied resource-rich patches relative to resource-poor patches by allocating more growth to very fine roots. We report the first example of significant differences between vegetation types (grassland and forest) in root responses to soil resource heterogeneity measured in a field experiment. The relatively high ability of forest roots to more fully occupy resource-rich patches is consistent with the global expansion of woody vegetation and associated increases in soil heterogeneity.

Plain Language Summary

The goal of this study was to measure how soil properties affect roots in grasslands and aspen forests. All measured root behaviour differed between soil types and most differed between vegetation types. The main finding of our work is that aspen forests adjusted more of their rooting behaviours compared to grasslands, which may contribute to the expansion of trees into surrounding grasslands.