TY - JOUR

T1 - High turnover of fungal hyphae in incubation experiments

AU - De Vries, Franciska

AU - Bååth, Erland

AU - Kuyper, Thom W.

AU - Bloem, Jaap

PY - 2009/3

Y1 - 2009/3

N2 - Soil biological studies are often conducted on sieved soils without the presence of plants. However, soil fungi build delicate mycelial networks, often symbiotically associated with plant roots (mycorrhizal fungi). We hypothesized that as a result of sieving and incubating without plants, the total fungal biomass decreases. To test this, we conducted three incubation experiments. We expected total and arbuscular mycorrhizal (AM) fungal biomass to be higher in less fertilized soils than in fertilized soils, and thus to decrease more during incubation. Indeed, we found that fungal biomass decreased rapidly in the less fertilized soils. A shift towards thicker hyphae occurred, and the fraction of septate hyphae increased. However, analyses of phospholipid fatty acids (PLFAs) and neutral lipid fatty acids could not clarify which fungal groups were decreasing. We propose that in our soils, there was a fraction of fungal biomass that was sensitive to fertilization and disturbance (sieving, followed by incubation without plants) with a very high turnover (possibly composed of fine hyphae of AM and saprotrophic fungi), and a fraction that was much less vulnerable with a low turnover (composed of saprotrophic fungi and runner hyphae of AMF). Furthermore, PLFAs might not be as sensitive in detecting changes in fungal biomass as previously thought.

AB - Soil biological studies are often conducted on sieved soils without the presence of plants. However, soil fungi build delicate mycelial networks, often symbiotically associated with plant roots (mycorrhizal fungi). We hypothesized that as a result of sieving and incubating without plants, the total fungal biomass decreases. To test this, we conducted three incubation experiments. We expected total and arbuscular mycorrhizal (AM) fungal biomass to be higher in less fertilized soils than in fertilized soils, and thus to decrease more during incubation. Indeed, we found that fungal biomass decreased rapidly in the less fertilized soils. A shift towards thicker hyphae occurred, and the fraction of septate hyphae increased. However, analyses of phospholipid fatty acids (PLFAs) and neutral lipid fatty acids could not clarify which fungal groups were decreasing. We propose that in our soils, there was a fraction of fungal biomass that was sensitive to fertilization and disturbance (sieving, followed by incubation without plants) with a very high turnover (possibly composed of fine hyphae of AM and saprotrophic fungi), and a fraction that was much less vulnerable with a low turnover (composed of saprotrophic fungi and runner hyphae of AMF). Furthermore, PLFAs might not be as sensitive in detecting changes in fungal biomass as previously thought.

KW - saprotrophic fungi

KW - arbuscular mycorrhizal fungi (AMF)

KW - phospholipid fatty acid (PLFA)

KW - neutral lipid fatty acid (NLFA)

KW - microscopic counting

U2 - 10.1111/j.1574-6941.2008.00643.x

DO - 10.1111/j.1574-6941.2008.00643.x

M3 - Journal article

VL - 67

SP - 389

EP - 396

JO - FEMS Microbiology Ecology

JF - FEMS Microbiology Ecology

SN - 0168-6496

IS - 3

ER -