Wx. Zhu et al., THE EFFECTS OF LIVE AND DEAD ROOTS ON SOIL FUNGI IN SPODOSOLIC SOILS OF THE NEW-JERSEY PINELANDS, Biology and fertility of soils, 21(3), 1996, pp. 215-226
The effects of live and dead roots on soil fungi were investigated exp
erimentally in a spodosolic soil of the New Jersey Pinelands. Field me
socosm plots were constructed to have a layer of either C- and N-rich
organic soil or a vermiculite substitute overlying a layer of sandy mi
neral soil with a very low organic content. The plots were also suppli
ed with live pitch pine and blueberry roots or dead pitch pine roots i
n varying quantities based on naturally occurring densities (half, sam
e, and double the ambient quantities). All plots were sampled 1 year a
fter construction (June 1991), and three more times in two subsequent
years (November 1991, June 1992, June 1993). In the presence of live r
oots, fluorescein diacetate-determined (FDA-active) fungal hyphae, tot
al fungal hyphae, and soil moisture decreased significantly in the org
anic material, while no change was associated with the dead roots. The
FDA-active fungal length in the live-root plots ranged from 40 to 165
mg(-1) soil, and from 55 to 335 mg(-1) soil in the dead-root plots. W
hile the total fungal length in live-root plots remained constant over
time (similar to 3000 m g(-1) soil), the total fungal length in the d
ead-root plots increased from an initial value of 3000 to > 4000 m g(-
1) soil at the conclusion of the study. Fungal lengths in mineral soil
were higher under organic material than under the vermiculite substit
ute. Soil moisture was higher in the presence of live roots in mineral
soils, but this did not increase the fungal abundance. Inputs of dead
roots did not alter the fungal abundance. Overall, we demonstrated th
at live and dead roots had different effects on fungal abundance in so
ils with contrasting qualities, and in a spodosolic forest soil, roots
could have ecosystem effects very different from those in agricultura
l soils.