Taj. Van Der Krift et al., Plant species and nutritional-mediated control over rhizodeposition and root decomposition, PLANT SOIL, 228(2), 2001, pp. 191-200
This study focuses on the influence of nitrogen (N) availability and specie
s on rhizodeposition and on decomposition of rhizodeposits, roots and soil
organic matter. Four perennial grass species were studied that are characte
ristic of grassland habitats that differ in nutrient availability. These pe
rennial grass species, Holcus lanatus L., Festuca rubra L., Anthoxanthum od
oratum L. and Festuca ovina L., were homogeneously labeled with (CO2)-C-14.
Plants were grown on soil without N addition and with N addition (14 g N m
(-2)). After 8 weeks, plants were harvested and root production and the rem
aining amount of rhizodeposits in the soil were measured. C-14-labelled roo
ts were incubated in fresh soil. Decomposition was measured of 1) the label
ed rhizodeposits in the soil in which the plants had been growing and 2) th
e labeled dead roots incubated in fresh soil, by trapping the evolved (CO2)
-C-14, over 69 days.
In general, decomposability of both roots and rhizodeposits increased when
nitrogen availability increased. Moreover, the species differed in their re
sponse to N. Higher N supply increased total rhizodeposition of H. lanatus
and the decomposability of rhizodeposited carbon compounds of this high fer
tility species was greater than of the low fertility species F. ovina, but
lower than of A. odoratum. The presented study gives no evidence for a rela
tion between root decomposition rate and the nutrient availability of the h
abitat of the four species. Overall, we suggest on the basis of the results
that species can affect nutrient cycling by differences in rates of rhizod
eposition and litter production. This offers a mechanism whereby species ca
n influence species replacement during succession.