AM真菌在生态系统中的作用

杨利霞

AM真菌在生态系统中的作用




Forests accumulate and store large amounts of carbon (C), and a sub
9 r8 t& A( H0 A( h/ p/ _9 ?stantial fraction of this stock is contained in deadwood. This transient pool is subject
. _; p# W; J9 A& Dto decomposition by deadwood-associated organisms, and in this process it contrib
utes to CO2
emissions. Although fungi and bacteria are known to colonize dead
- O. u, ]) R& N5 i: t2 m/ Vwood, little is known about the microbial processes that mediate carbon and nitro
, w# ^1 m/ }5 Z- zgen (N) cycling in deadwood. In this study, using a combination of metagenomics,
metatranscriptomics, and nutrient flflux measurements, we demonstrate that the decom
: R/ [  s$ C# X* k& y* ]6 jposition of deadwood reflflects the complementary roles played by fungi and bacteria.
Fungi were found to dominate the decomposition of deadwood and particularly its re
) L3 V# ?2 W: I6 P8 Xcalcitrant fractions, while several bacterial taxa participate in N accumulation in dead
wood through N fifixation, being dependent on fungal activity with respect to deadwood
2 `/ d+ B5 L" T" u5 Ucolonization and C supply. Conversely, bacterial N fifixation helps to decrease the con
straints of deadwood decomposition for fungi. Both the CO2 efflflux and N accumulation
% Q$ L% |3 P& R0 f& Bthat are a result of a joint action of deadwood bacteria and fungi may be signifificant for
# h# T8 a3 A* j' `; y1 U' Enutrient cycling at ecosystem levels. Especially in boreal forests with low N stocks, dead
wood retention may help to improve the nutritional status and fertility of soils.
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