We conducted a field experiment in two
alpine meadows to investigate the short-term effects
of nitrogen enrichment and plant litter biomass on
plant species richness, the percent cover of functional
groups, soil microbial biomass, and enzyme activity
in two alpine meadow communities. The addition of
nitrogen fertilizer to experimental plots over two
growing seasons increased plant production, as
indicated by increases in both the living plant biomass
and litter biomass in the Kobresia humilis meadow
community. In contrast, fertilization had no significant
effect on the amounts of living biomass and litter
biomass in the K. tibetica meadow. The litter
treatment results indicate that litter removal significantly
increased the living biomass and decreased the
litter biomass in the K. humilis meadow; however,
litter-removal and litter-intact treatments had no
impact on the amounts of living biomass and litter
biomass in the K. tibetica meadow. Litter production
depended on the degree of grass cover and was also
influenced by nitrogen enrichment. The increase in
plant biomass reflects a strong positive effect of
nitrogen enrichment and litter removal on grasses in
the K. humilis meadow. Neither fertilization nor litter
removal had any impact on the grass biomass in the
K. tibetica meadow. Sedge biomass was not significantly
affected by either nutrient enrichment or litter
removal in either alpine meadow community. The
plant species richness decreased in the K. humilis
meadow following nitrogen addition. In the K.
humilis meadow, microbial biomass C increased
significantly in response to the nitrogen enrichment
and litter removal treatments. Enzyme activities
differed depending on the enzyme and the different
alpine meadow communities; in general, enzyme
activities were higher in the upper soil layers (0–
10 cm and 10–20 cm) than in the lower soil layers
(20–40 cm). The amounts of living plant biomass and
plant litter biomass in response to the different
treatments of the two alpine meadow communities
affected the soil microbial biomass C, soil organic C,
and soil fertility.
These results suggest that the original soil conditions,
plant community composition,
and community productivity are very important
in regulating plant community productivity and
microbial biomass and activity.
The research has been published on Plant Soil (2010)
331:377–389
DOI 10.1007/s11104-009-0259-8
Changting Wang & Ruijun Long & Qilan Wang &
Wei Liu & Zengchun Jing & Li Zhang