Root morphology and mycorrhizal type strongly influence root production in nutrient hot spots of mixed forests

Journal Article · Thu May 25 00:00:00 EDT 2017 · Journal of Ecology

DOI:https://doi.org/10.1111/1365-2745.12800· OSTI ID:1419620

Chen, Weile ^[1]; Koide, Roger T. ^[2]; Eissenstat, David M.  ^[1]

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1. Pennsylvania State Univ., University Park, PA (United States)
2. Pennsylvania State Univ., University Park, PA (United States); Brigham Young Univ., Provo, UT (United States)

Plants compete for nutrients using a range of strategies. We investigated nutrient foraging within nutrient hot-spots simultaneously available to plant species with diverse root traits. We hypothesized that there would be more root proliferation by thin-root species than by thick-root species, and that root proliferation by thin-root species would limit root proliferation by thick-root species. We conducted a root ingrowth experiment in a temperate forest in eastern USA where root systems of different tree species could interact. Tree species varied in the thickness of their absorptive roots, and were associated with either ectomycorrhizal (EM) or arbuscular mycorrhizal (AM) fungi. Thus, there were thin- and thick-root AM and thin- and thick-root EM plant functional groups. Half the ingrowth cores were amended with organic nutrients (dried green leaves). Relative root length abundance, the proportion of total root length in a given soil volume occupied by a particular plant functional group, was calculated for the original root population and ingrowth roots after 6 months. The shift in relative root length abundance from original to ingrowth roots was positive in thin-root species but negative in thick-root species (p < .001), especially in unamended patches (AM: +6% vs. -7%; EM: +8% vs. -9%). Being thin-rooted may thus allow a species to more rapidly recolonize soil after a disturbance, which may influence competition for nutrients. Moreover, we observed that nutrient additions amplified the shift in root length abundance of thin over thick roots in AM trees (+13% vs. -14%), but not in EM trees (+1% vs -3%). In contrast, phospholipid fatty acid biomarkers suggested that EM fungal hyphae strongly proliferated in nutrient hot-spots whereas AM fungal hyphae exhibited only modest proliferation. We found no evidence that when growing in the shared patch, the proliferation of thin roots inhibited the growth of thick roots. As a result, knowledge of root morphology and mycorrhizal type of co-existing tree species may improve prediction of patch exploitation and nutrient acquisition in heterogeneous soils.

• Research Organization: Pennsylvania State Univ., University Park, PA (United States)
• Sponsoring Organization: Office of Science (SC), Biological and Environmental Research (BER). Earth and Environmental Systems Science Division
• Contributing Organization: NSF
• Grant/Contract Number: SC0012003
• OSTI ID: 1419620
• Alternate ID(s): OSTI ID: 1411152
• Journal Information: Journal of Ecology, Vol. 106, Issue 1; ISSN 0022-0477
• Publisher: Wiley
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
arbuscular mycorrhiza
ectomycorrhiza
ingrowth
nutrient foraging
plant–soil interactions
resource exploitation
root competition
root length density
root proliferation
soil heterogeneity