Effects of pine roots on microorganisms, fauna, and nitrogen availability in two soil horizons of a coniferous forest spodosol

Parmelee, Robert W.; Ehrenfeld, Joan G.; Tate, Robert L.

doi:10.1007/bf00336428

Cited by 73 publications

(31 citation statements)

References 25 publications

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“…The impact of soil fauna on decomposition has been related to their stimulatory effect on soil saprobic fungi and bacteria (Anderson, 1988;Elliott et al, 1988;Seastedt, 1984). In both this experiment and a previous study , we found, however, no change in microbial biomass with respect to live root inputs, although an increased microbial growth rate was detected by Parmelee et al (1993). Our results are also consistent with the findings of Coleman et al (1984), who showed that nematodes increased carbon and nitrogen mineralization while decreasing bacterial densities.…”

Section: Discussionsupporting

confidence: 83%

“…This result is consistent with our previous greenhouse experiments, where live pitch pine roots stimulated an 8-fold increase in nematode densities (Parrrielee et al, 1993(Parrrielee et al, , 1995. Higher decomposition rates, coupled with higher nematode abundances in soils containing live roots, are consistent with the suggestions that mycorrhizal roots could change the pattern of decomposition by stimulating and sustaining higher densities of soil fauna (Cromack et al, 1988;Ingham et al, 1985;Parmelee et al, 1993). The impact of soil fauna on decomposition has been related to their stimulatory effect on soil saprobic fungi and bacteria (Anderson, 1988;Elliott et al, 1988;Seastedt, 1984).…”

Section: Discussionsupporting

confidence: 68%

“…The numerous studies of the effects of roots on decomposition and related processes in the soil have, however, produced contradictory results. Many studies (Faber and Verhoef, 1991;Fisher and Gosz, 1986a;Gadgil, 1971, 1975;Parmelee et al, 1993;Staaf, 1988) have shown that in forest soils, roots often retard decomposition rates, and decrease soil moisture, extractable inorganic N, and N mineralization rates. Such effects could reflect competitive withdrawals of nutrients from the litter by the roots, as well as changes in soil moisture and soil nutrient levels.…”

Section: Introductionmentioning

confidence: 99%

“…In C-and N-rich organic horizons, roots depressed total microbial biomass (Parmelee et al, 1993;Tate et al, 1991) and fungal biomass ; soil moisture and extractable inorganic N were decreased concurrently in these microcosms. In the C-and N-poor mineral soil material from the E horizon of a spodosolic soil, however, the presence of tree roots was associated with greater microbial growth rates and greatly increased microfaunal populations (Parmelee et al, 1993;Tate et al, 1991).…”

Section: Introductionmentioning

confidence: 99%

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The effects of mycorrhizal roots on litter decomposition, soil biota, and nutrients in a spodosolic soil

Zhu

Ehrenfeld

1996

Plant Soil

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We studied the effects of mycorrhizal pitch pine (Pinus rigida) roots on litter decomposition, microbial biomass, nematode abundance and inorganic nutrients in the E horizon material of a spodosolic soil, using field microcosms created in a regenerating pitch pine stand in the New Jersey Pinelands. Pine roots stimulated litter decomposition by 18.7% by the end of the 29 month study. Both mass loss and N and P release from the litter were always higher in the presence of roots than in their absence. Nutrient concentrations in decomposing litter were similar, however, in the presence and absence of roots, which suggests that the roots present in the with-root treatment did not withdraw nutrients directly from the litter. The soil was slightly drier in the presence of roots, but there was no discernible effect on soil microbial biomass. The effects of roots on soil extractable inorganic nutrients were inconsistent. Roots, however, were consistently associated with higher numbers of soil nematodes. These results suggest that, in soils with low total C and N contents, roots stimulate greater activity of the soil biota, which contribute, in turn, to faster litter decomposition and nutrient release.

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Section: Discussionsupporting

confidence: 83%

Section: Discussionsupporting

confidence: 68%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

The effects of mycorrhizal roots on litter decomposition, soil biota, and nutrients in a spodosolic soil

Zhu

Ehrenfeld

1996

Plant Soil

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“…Microbial biomass has been shown to correlate with aboveground primary production (Wardle 1992;Zak et al 1994;Wardle and Barker 1997), and to be responsive to those aboveground trophic interactions, such as herbivory, that aect root exudation (reviewed by Bardgett et al 1998). Since soil microbes are consumed by microbivorous animals, changes in microbial biomass and production can be re¯ected in the biomasses of upper trophic groups of soil food webs (Sohlenius 1990;Christensen et al 1992;Griths et al 1992;Parmelee et al 1993;Griths 1994). Mikola and SetaÈ laÈ (1998b) found that in simple heterotrophic food webs containing microbes and nematodes, increased microbial production led to increases in the biomass of microbes and microbivores, and to a marginal increase in the biomass of top predators (i.e., consumers of microbivores).…”

Section: Introductionmentioning

confidence: 98%

Effects of microbivore species composition and basal resource enrichment on trophic-level biomasses in an experimental microbial-based soil food web

Mikola

1998

Oecologia

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Previous theoretical and empirical evidence suggests that species composition within trophic levels may profoundly affect the response of trophic-level biomasses to enhanced basal resources. To test whether species composition of microbivorous nematodes has such an effect in microbial-based soil food webs, I created three microcosm food webs, consisting of bacteria, fungi, bacterial-feeding nematodes (Acrobeloides tricornus, Caenorhabditis elegans), fungal-feeding nematodes (Aphelenchus avenae, Aphelenchoides sp.) and a predatory nematode (Prionchulus punctatus). The food webs differed in species composition at the second trophic level: food web A included A. tricornus and Aph. avenae, food web B included C. elegans and Aphelenchoides sp., and food web AB included all four species. I increased basal resources by adding glucose to half of the replicates of each food web, and sampled microcosms destructively four times during a 22-week experiment to estimate the biomass of organisms at each trophic level. Microbivore species composition significantly affected bacterivore and fungivore biomass but not bacterial, fungal or predator biomass. Greatest bacterivore and fungivore biomass was found in food web A, intermediate biomass in food web AB, and smallest biomass in food web B. Basal resource addition increased the biomass of microbes and microbivores but did not affect predator biomass. Importantly, microbivore species composition did not significantly modify the effect of additional resources on trophic-level biomasses. The presence of a competitor reduced the biomass of A. tricornus and Aph. avenae, in that the biomass of these species was less in food web AB than in food web A, whereas the biomass of C. elegans and Aphelenchoides sp. was not affected by their potential competitors. The biomass of Aph. avenae increased with additional resources in the absence of the competitor only, while the biomass of A. tricornus and Aphelenchoides sp. increased also in the presence of their competitors. The results imply that microbivore species composition may determine the second-level biomass in simple microbe-nematode food webs, but may not significantly affect biomass at other levels or modify the response of trophic-level biomasses to enhanced basal resources. The study also shows that even if the role of predation in a food web is diminished, the positive response of organisms to increased resource availability may still be hindered by competition.

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Mycorrhizosphere: Strategies and Functions

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Effects of pine roots on microorganisms, fauna, and nitrogen availability in two soil horizons of a coniferous forest spodosol

Cited by 73 publications

References 25 publications

The effects of mycorrhizal roots on litter decomposition, soil biota, and nutrients in a spodosolic soil

The effects of mycorrhizal roots on litter decomposition, soil biota, and nutrients in a spodosolic soil

Effects of microbivore species composition and basal resource enrichment on trophic-level biomasses in an experimental microbial-based soil food web

Mycorrhizosphere: Strategies and Functions

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