水保所知识产出(1956---)知识库

Aims Alpine ecosystems are important terrestrial
carbon (C) pools, and microbial decomposers play
a key role in cycling soil C. Microbial metabolic
limitations in these ecosystems, however, have
rarely been studied. The objectives of this study
are to reveal the characteristics of microbial nutrientlimitation, and decipher the drivers in the alpine
ecosystems.
Methods Models of extracellular enzymatic stoichi-
ometry were applied to examine and compare the
metabolic limitations of the microbial communities
in bulk and rhizosphere soils along an altitudinal
gradient (2800–3500 m a.s.l.) under the same type
of vegetation (Abies fabri) on Gongga Mountain,
eastern Tibetan Plateau.
Results The soil microbial communities suffered from
relative C and phosphorus (P) limitations in the alpine
ecosystem despite of high soil nutrient contents here.
Partial least squares path modelling (PLS-PM) revealed
that the limitations were directly regulated by soil nutri-
ent stoichiometry, followed by nutrient availability. The
C and P limitations were higher at the high altitudes
(3000–3500 m) than that at the low altitude (2800 m),
which mainly attribute to changes of soil temperature
and moisture along the altitudinal gradient. This sug-
gested that global warming may relieve microbial met-
abolic limitation in the alpine ecosystems, and then is
conducive to the retention of organic C in soil. Further-
more, the C and P limitations varied significantly be-
tweenthebulkandrhizospheresoilsatthehighaltitudes
(3200–3500 m), but not at the low altitudes. This indi-
cated the influences of vegetation on the microbial me-
tabolisms,while the influencescould decreaseunder the
scenario of global warming.
Conclusions Our study suggests that the alpine ecosys-
tems with high organic C storage harbour abundant
microbial populations limited byrelativeCand P, which
have sensitive metabolic characteristics. This could thuspotentially lead to large fluctuations in the soil C turn-
over under climate change. The study provides impor-
tant insights linking microbial metabolisms to the envi-
ronmental gradients, and improvesour understanding of
C cycling in alpine ecosystems.