Fine root decomposition, nutrient mobilization and fungal communities in a pine forest ecosystemby Ang Li, Timothy J. Fahey, Teresa E. Pawlowska, Melany C. Fisk, James Burtis

Soil Biology and Biochemistry


Microbiology / Soil Science


liz a b 53, nive

Received in revised form 16 January 2015

Accepted 20 January 2015

Available online 30 January 2015

Despite its importance to energy flow and nutrient cycling the process of fine root decomposition has been paid to root decomposition, and only a few principles have been established concerning factors that regulate the root decay process (Berg, 1984; Hobbie et al., 2010; Goebel et al., 2011). In a ratio and Ca conotranspiration are e possible roles of ve not been thortions with rhizoet al., 2004). Root ese pre-mortality robial community at the rhizosphere organisms have a strong impact on root decay patterns following root senescence. In fact, Langley et al. (2006) suggested that fungal colonization, including its effect on root chemistry, could play a key role in regulating fine root decomposition. Studies of saprotrophic fungi on leaf litter indicate that an important component of the decomposition process is the formation of fungal hyphal networks, through which organic C and mineral nutrients are transported, thereby facilitating the utilization of heterogeneous soil organic matter substrates (Tlalka et al., 2008). Hyphal networks also could * Corresponding author. Tel.: þ1 607 255 5470; fax: þ1 607 255 0349.

E-mail addresses: (A. Li), (T.J. Fahey), (T.E. Pawlowska), (M.C. Fisk), jb766@ (J. Burtis). 1

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Soil Biology & Biochemistry 83 (2015) 76e83Present address: 1450 E 55th Pl, Apt 618-S, Chicago, IL, 60637, USA.Root turnover and decomposition is a major pathway of carbon and nutrient flux to soil (Parton et al., 2007; Bird et al., 2008). At the global scale, fine root turnover has been estimated to account for over one-third of net primary productivity (Jackson et al., 1997).

Inputs of organic matter from dead fine roots can result in more C stabilized in soil and more nutrients released than aboveground litter (Vogt et al., 1986). Despite the importance of fine roots to soil

C sequestration and nutrient cycling, relatively little attention has gested that root chemistry indices, such as C:N centration, and climatic factors like actual evap the primary controllers of root decomposition. Th decay microorganisms and soil environment ha oughly evaluated. Roots form complex associa spheremicrobes throughout their life time (Singh decay microorganisms are derived from both th rhizosphere microbes and the wider soil mic (Fisk et al., 2011). Some studies have shown th1. Introduction review of root decomposition data, Silver and Miya (2001) sug-Keywords:





Phosphorus 454 pyrosequencing 0038-0717/© 2015 Elsevier Ltd. All rights reserved.ration of root litterbags for decomposition studies could affect decay rates and nutrient mobilization in part by altering the community of decay organisms. We compared rates of decomposition and nutrient release from fine roots of pine between litterbags and intact cores and characterized the fungal community in the decomposing roots. Fine root decomposition was about twice as fast overall for intact cores than litterbags, and rapid mobilization of N and P was observed for roots in cores whereas nutrients were immobilized in litterbags. Fungal communities characterized using 454 pyrosequencing were considerably different between decaying roots in intact cores and litterbags. Most interesting, taxa from ectomycorrhizal fungal orders such as Boletales, Thelephorales and Cantharellales appeared to be more common in decaying roots from cores than litterbags. Moreover, the rate of N and P mobilization from decaying fine roots was highly correlated with taxa from two orders of ectomycorrhizal fungi (Thelephorales, Cantharellales). Although we caution that DNA identified from the decaying roots cannot be conclusively ascribed to active fungi, the results provide tentative support for a significant role of ectomycorrhizal fungi in decomposition and nutrient mobilization from fine roots of pine. © 2015 Elsevier Ltd. All rights reserved.Article history:

Received 19 November 2014 received comparatively little detailed research. Disruption of the fine root-soil interface during prepa-a r t i c l e i n f o a b s t r a c tFine root decomposition, nutrient mobi communities in a pine forest ecosystem

Ang Li a, 1, Timothy J. Fahey a, *, Teresa E. Pawlowsk a Department of Natural Resources, G16 Fernow Hall, Cornell University, Ithaca, NY 148 b Department of Plant Pathology & Plant-Microbe Biology, 334 Plant Science, Cornell U c Zoology Department, 160 Pearson Hall, Miami University, Oxford, OH 45069, USAation and fungal , Melany C. Fisk c, James Burtis a

USA rsity, NY 14853, USA le at ScienceDirect

Biochemistry evier .com/locate/soi lbio

Biocplay an important role in root decomposition because of the highly heterogeneous distribution of dead fine roots in soil.

The role of soil heterogeneity in root decay has also received little study. In northern forest ecosystems, fine roots are distributed in both organic and mineral soil horizons, which differ in C availability, nutrient status, moisture, faunal abundance, microbial community, and edaphic conditions (Parmelee et al., 1993). Microbes living in surface organic horizons depend primarily on labile

C supply from leaf litter and are often N limited, whereas microbes living in mineral soils derive much of their C and energy from recalcitrant soil organic matter and are limited primarily by C (Fontaine and Barot, 2005). Thus, dead roots of the same individual tree decay in very different physical and biotic environments, as shown previously for conifer needle litter (Osono et al., 2006). Also, fine roots in organic and mineral soil horizons differ significantly in organic matter quality and mineral nutrient concentrations (Fahey et al., 1988). These differences in root chemistry, decomposers, and environment between organic and mineral soils may lead to distinct patterns of fine root decomposition in the two soil horizons.