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Root production is determined by radiation flux in a temperate grassland community

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JournalGlobal Change Biology
DatePublished - Feb 2004
Issue number2
Volume10
Number of pages19
Pages (from-to)209-227
Original languageEnglish

Abstract

Accurate knowledge of the response of root turnover to a changing climate is needed to predict growth and produce carbon cycle models. A soil warming system and shading were used to vary soil temperature and received radiation independently in a temperate grassland dominated by Holcus lanatus L. Minirhizotrons allowed root growth and turnover to be examined non-destructively. In two short-term (8 week) experiments, root responses to temperature were seasonally distinct. Root number increased when heating was applied during spring, but root death increased during autumnal heating. An experiment lasting 12 months demonstrated that any positive response to temperature was short-lived and that over a full growing season, soil warming led to a reduction in root number and mass due to increased root death during autumn and winter. Root respiration was also insensitive to soil temperature over much of the year. In contrast, root growth was strongly affected by incident radiation. Root biomass, length, birth rate, number and turnover were all reduced by shading. Photosynthesis in H. lanatus exhibited some acclimation to shading, but assimilation rates at growth irradiance were still lower in shaded plants. The negative effects of shading and soil warming on roots were additive. Comparison of root data with environmental measurements demonstrated a number of positive relationships with photosynthetically active radiation, but not with soil temperature. This was true both across the entire data set and within a shade treatment. These results demonstrate that root growth is unlikely to be directly affected by increased soil temperatures as a result of global warming, at least in temperate areas, and that predictions of net primary productivity should not be based on a positive root growth response to temperature.

Bibliographical note

© 2004 Blackwell Publishing Ltd. This is an electronic version of an article published in Global Change Biology complete citation information for the final version of the paper, as published in the print edition of Global Change Biology, is available on the Blackwell Synergy online delivery service, accessible via the journal's website at www.blackwellpublishing.com/journal.asp?ref=1354-1013 or www.blackwell-synergy.com

    Research areas

  • acclimation, belowground net primary production, grassland, Holcus lanatus, minirhizotrons, Plantago lanceolata, received photosynthetically active radiation, root demography, root respiration, root turnover, shading, soil warming, temperature, NORTHERN HARDWOOD FORESTS, SOIL-TEMPERATURE, CLIMATE-CHANGE, PHOTOSYNTHETIC ACCLIMATION, NITROGEN AVAILABILITY, ZONE TEMPERATURE, NUTRIENT-UPTAKE, CARBON-DIOXIDE, CO2 EXCHANGE, LEAF-AREA

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