水保所知识产出(1956---)知识库

Purpose Knowledge of soil N cycling and the associated functional microbial groups of N 2 O production under different
management measures could provide clues for the restoration of degraded meadows in alpine ecosystems.
Materials and methods We investigated soil N 2 O emissions, the genes related to N 2 O production and reduction (AOA-amoA,
AOB-amoA, nirK, nirS, and nosZ), and associated microbial communities in four meadows (continuous grazing, grazing
exclusion by fencing, grazing exclusion by combined fencing and reseeding, and undisturbed meadow) in the Tibetan Plateau
to reveal the mechanism underlying potential N 2 O emissions in alpine meadows.
Results and discussion Compared to the grazing meadow, fencing and fencing + reseeding meadows had lower N 2 O emis-
sions and lower abundances of AOA-amoA, AOB-amoA, nirK, nirS, and nosZ genes, suggesting that grazing exclusion
could decrease the soil N-turnover potential. However, the higher N 2 O emissions compared to those of undisturbed mead-
ows indicated that longer restoration periods were necessary. Seeding the fenced meadow did not alter soil N 2 O emission
or the abundance of AOA-amoA, AOB-amoA, nirK, nirS, and nosZ genes, possibly owing to the similar soil nutrient status
compared to that of the fencing meadow. Grazing exclusion also resulted in significant changes in the community diversity
and composition of microbes harboring these functional genes, especially nirK and nosZ communities. N 2 O emissions
were significantly associated with microbial communities involved in N 2 O production and reduction but not with the gene
abundance of AOA-amoA, AOB-amoA, nirK, nirS, and nosZ. Soil dissolved organic nutrients, including C and N, and soil
moisture were the controlling factors for N 2 O production by altering the community composition of nirK- and nosZ-type
denitrifiers, such as Bradyrhizobiaceae, Rhizobiaceae, Brucellaceae, Ochrobactrum, and Proteobacteria.
Conclusions Our results indicated that grazing-induced elevation of potential N 2 O emissions from meadow soil could be
alleviated by grazing exclusion, including sole fencing and a combination of fencing and reseeding, by changing soil dis-
solved organic nutrients and moisture thus regulating the microbial communities.