Which processes drive fine root elongation in a natural mountain forest ecosystem?

Background: Quantifying the dynamics of root growth is vital when characterising the role of vegetation in carbon cycling. Aims: We examined the temporal dynamics of root growth and responses to spatial (altitude, forest patchiness and soil depth) and biological factors (root diameter and root topology) in mid-montane and upper montane coniferous forest ecosystems. Methods: Using rhizotrons, two indicators were investigated: occurrence, i.e. the proportion of roots which had elongated since the previous measurement of root elongation (%), and daily root elongation speed (mm d−1) once the elongation occurred. Results: Spatial factors had a limited effect on root growth. Roots in the same diameter class possessed different elongation speeds and this was related to topological ranking, reflecting a disparity in physiological activity. Temporally, the occurrence of root elongation reached a peak in May–October (up to 90%) and sharply dropped after October 2010. The maximum root elongation speed (mean: 3.0 mm d−1) was measured in July–August. Root growth was the most inactive in February 2011 but some roots still exhibited positive elongation speeds (mean: 0.5 mm d−1). Occurrence and speed of elongation reacted differently with regard to environmental and biological factors. Conclusions: Temporal and biological factors contributed more towards explaining the variability of root growth than spatial factors. In future studies, both occurrence and speed of elongation should be used to characterise root growth.

[1]  Y. Liu,et al.  Anatomical traits associated with absorption and mycorrhizal colonization are linked to root branch order in twenty-three Chinese temperate tree species. , 2008, The New phytologist.

[2]  O. Björkman.  Responses to Different Quantum Flux Densities , 1981 .

[3]  D. Eissenstat,et al.  Anatomical characteristics of roots of citrus rootstocks that vary in specific root length. , 1999, New Phytologist.

[4]  H. M. Taylor,et al.  The Rhizotron as a Tool for Root Research , 1982 .

[5]  F. Xiong,et al.  Photosynthetic and respiratory acclimation and growth response of Antarctic vascular plants to contrasting temperature regimes. , 2000, American journal of botany.

[6]  P. Hanson,et al.  Factors controlling the timing of root elongation intensity in a mature upland oak stand , 2004, Plant and Soil.

[7]  Carl C. Trettin,et al.  The Response of Belowground Carbon Allocation in Forests to Global Change , 2005 .

[8]  D. Phillips,et al.  Effects of elevated CO2, N-fertilization, and season on survival of ponderosa pine fine roots. , 2000 .

[9]  Takuo Hishi.  Heterogeneity of individual roots within the fine root architecture: causal links between physiological and ecosystem functions , 2007, Journal of Forest Research.

[10]  J. Baldwin.  Competition for plant nutrients in soil; a theoretical approach , 1976, The Journal of Agricultural Science.

[11]  J. Bloomfield,et al.  Analysis of some direct and indirect methods for estimating root biomass and production of forests at an ecosystem level , 1998, Plant and Soil.

[12]  P. Bénichou,et al.  Prix Norbert Gerbier 1986: prise en compte de la topographie pour la cartographie des champs pluviométriques statistiques , 1987 .

[13]  E. Blancaflor,et al.  Functional analysis of the Arabidopsis PHT4 family of intracellular phosphate transporters. , 2008, The New phytologist.

[14]  C. Watson,et al.  Influences of Root Diameter, Tree Age, Soil Depth and Season on Fine Root Survivorship in Prunus avium , 2005, Plant and Soil.

[15]  F. Lebourgeois,et al.  Appréhender le niveau de sécheresse dans le cadre des études stationnelles et de la gestion forestière à partir d'indices bioclimatiques. , 2005 .

[16]  D. Hertel,et al.  Norway Spruce Shows Contrasting Changes in Below- Versus Above-Ground Carbon Partitioning towards the Alpine Treeline: Evidence from a Central European Case Study , 2011 .

[17]  N. Buchmann,et al.  Soil respiration fluxes in a temperate mixed forest: seasonality and temperature sensitivities differ among microbial and root-rhizosphere respiration. , 2010, Tree physiology.

[18]  S. Zechmeister-Boltenstern,et al.  Winter soil respiration from an Austrian mountain forest , 2007 .

[19]  Hervé Rey,et al.  Modelling and simulation of the architecture and development of the oil-palm (Elaeis guineensis Jacq.) root system , 2004, Plant and Soil.

[20]  Alexia Stokes,et al.  Engineering ecological protection against landslides in diverse mountain forests: Choosing cohesion models , 2012 .

[21]  U. Schurr,et al.  Environmental effects on spatial and temporal patterns of leaf and root growth. , 2009, Annual review of plant biology.

[22]  J. Stewart,et al.  Physiology of cotton , 2010 .

[23]  Alexia Stokes,et al.  Modelling root demography in heterogeneous mountain forests and applications for slope stability analysis , 2012, Plant and Soil.

[24]  G. Schwarz.  Estimating the Dimension of a Model , 1978 .

[25]  J. R. Harris,et al.  Root and Shoot Growth Periodicity of Green Ash, Scarlet Oak, Turkish Hazelnut, and Tree Lilac , 1995 .

[26]  R. Q. Cannell.  Methods of Studying Root Systems . By W. Böhm. Berlin: Springer (1979), pp. 200, DM 69, $38.00. , 1980, Experimental Agriculture.

[27]  Christian Piedallu,et al.  Efficient assessment of topographic solar radiation to improve plant distribution models , 2008 .

[28]  Alastair H. Fitter,et al.  Morphometric analysis of root systems: application of the technique and influence of soil fertility on root system development in two herbaceous species , 1982 .

[29]  R. Ruess,et al.  Coupling fine root dynamics with ecosystem carbon cycling in black spruce forests of interior Alaska , 2003 .

[30]  Christina E. Wells,et al.  Beyond the Roots of Young Seedlings: The Influence of Age and Order on Fine Root Physiology , 2002, Journal of Plant Growth Regulation.

[31]  A. Riedacker.  Rythmes de croissance et de régénération des racines des végétaux ligneux , 1976 .

[32]  Julie D. Jastrow,et al.  Impacts of Fine Root Turnover on Forest NPP and Soil C Sequestration Potential , 2003, Science.

[33]  J. Devereux Joslin,et al.  Disturbances During Minirhizotron Installation Can Affect Root Observation Data , 1999 .

[34]  K. Thorup-Kristensen,et al.  Using coloured roots to study root interaction and competition in intercropped legumes and non-legumes , 2010 .

[35]  B. Dell,et al.  Growth of Eucalyptus marginata (Jarrah) seedlings in a greenhouse in response to shade and soil temperature. , 1993, Tree physiology.

[36]  Halin Zhao,et al.  Linking root morphology, longevity and function to root branch order: a case study in three shrubs , 2010, Plant and Soil.

[37]  Ram Oren,et al.  Irreconcilable Differences: Fine-Root Life Spans and Soil Carbon Persistence , 2008, Science.

[38]  R. B. Jackson,et al.  Global patterns of root turnover for terrestrial ecosystems , 2000 .

[39]  D. Hertel,et al.  Below-ground response of Norway spruce to climate conditions at Mt. Brocken (Germany)—A re-assessment of Central Europe's northernmost treeline , 2011 .

[40]  J. Bryant,et al.  REGULATION OF FINE ROOT DYNAMICS BY MAMMALIAN BROWSERS IN EARLY SUCCESSIONAL ALASKAN TAIGA FORESTS , 1998 .

[41]  H. Majdi,et al.  Root sampling methods - applications and limitations of the minirhizotron technique , 1996, Plant and Soil.

[42]  P. B. Tinker,et al.  Solute Movement in the Soil-Root System. , 1978 .

[43]  H. Asbjornsen,et al.  Review of root dynamics in forest ecosystems grouped by climate, climatic forest type and species , 1995, Plant and Soil.

[44]  Philip J. White,et al.  Solute is imported to elongating root cells of barley as a pressure driven-flow of solution. , 2004, Functional plant biology : FPB.

[45]  Hans Lambers,et al.  Plant Physiological Ecology , 1998, Springer New York.

[46]  Jens Hansen,et al.  Conifer carbohydrate physiology : Updating classical views , 1997 .

[47]  Harbin Li,et al.  Fine root heterogeneity by branch order: exploring the discrepancy in root turnover estimates between minirhizotron and carbon isotopic methods. , 2008, The New phytologist.

[48]  P. Hallett,et al.  Root elongation, water stress, and mechanical impedance: a review of limiting stresses and beneficial root tip traits. , 2011, Journal of experimental botany.

[49]  H. Lyr.  Effect of the root temperature on growth parameters of various European tree species , 1996 .

[50]  K. Pregitzer,et al.  Responses of tree fine roots to temperature , 2000 .

[51]  David Fletcher,et al.  Modelling skewed data with many zeros: A simple approach combining ordinary and logistic regression , 2005, Environmental and Ecological Statistics.

[52]  Christina E. Wells,et al.  MARKED DIFFERENCES IN SURVIVORSHIP AMONG APPLE ROOTS OF DIFFERENT DIAMETERS , 2001 .

[53]  M. Dhanoa,et al.  Effects of temperature on parameters of root growth relevant to nutrient uptake: Measurements on oilseed rape and barley grown in flowing nutrient solution , 1986, Plant and Soil.

[54]  T. Hinckley,et al.  Influence of temperature and water potential on root growth of white oak , 1981 .

[55]  M. Arbez.  Croissance des racines du Pin Laricio de Corse (Pinus nigra Arn, ssp Laricio), au stade juvénile : relation avec la croissance des parties aériennes et les facteurs du milieu , 1971 .

[56]  R. Delaune,et al.  Root studies under variable redox potential in soil or soil suspensions using laboratory rhizotrons , 1991, Vegetatio.

[57]  C. Piedallu,et al.  Multiscale computation of solar radiation for predictive vegetation modelling , 2007, Annals of Forest Science.

[58]  M. Kazda,et al.  Fine root dynamics in 60-year-old stands of Fagus sylvatica and Picea abies growing on haplic luvisol soil , 2010, European Journal of Forest Research.

[59]  Ross Ihaka,et al.  Gentleman R: R: A language for data analysis and graphics , 1996 .

[60]  H. M. Taylor,et al.  ROOT ELONGATION RATES OF COTTON AND PEANUTS AS A FUNCTION OF SOIL STRENGTH AND SOIL WATER CONTENT , 1969 .

[61]  Michael F. Allen,et al.  FINE ROOT ARCHITECTURE OF NINE NORTH AMERICAN TREES , 2002 .

[62]  Todd N. Rosenstiel,et al.  Climatic influences on net ecosystem CO2 exchange during the transition from wintertime carbon source to springtime carbon sink in a high-elevation, subalpine forest , 2005, Oecologia.

[63]  K. Pregitzer,et al.  Patterns of fine root mortality in two sugar maple forests , 1993, Nature.

[64]  D. Eissenstat,et al.  Root anatomy, morphology, and longevity among root orders in Vaccinium corymbosum (Ericaceae). , 2008, American journal of botany.

[65]  Christina E. Wells,et al.  Changes in the risk of fine-root mortality with age: a case study in peach, Prunus persica (Rosaceae). , 2002, American journal of botany.

[66]  D. Binkley,et al.  Tree Species Effects on Soils: Implications for Global Change , 2005 .

[67]  J. Farrar.  Respiration Rate of Barley Roots: its Relation to Growth, Substrate Supply and the Illumination of the Shoot , 1981 .

[68]  F. Boone,et al.  A case study on the effect of soil compaction on potato growth in a loamy sand soil; 1. physical measurements and rooting patterns , 1978 .

[69]  K. Pregitzer,et al.  Spatial variation in tree root distribution and growth associated with minirhizotrons , 1992, Plant and Soil.

[70]  P. Nye,et al.  The effect of temperature variation over the root system on root extension and phosphate uptake by rape , 1984, Plant and Soil.

[71]  D. Hertel,et al.  Fine root dynamics along a 2,000-m elevation transect in South Ecuadorian mountain rainforests , 2008, Plant and Soil.

[72]  J. Jansson,et al.  Interactions between arbuscular mycorrhizal fungi and bacteria and their potential for stimulating plant growth. , 2006, Environmental microbiology.

[73]  Christian Körner,et al.  A re-assessment of high elevation treeline positions and their explanation , 1998, Oecologia.

[74]  R. E. Dickson,et al.  Contrasting fine-root production, survival and soil CO2 efflux in pine and poplar plantations , 2000, Plant and Soil.