AM真菌在生态系统中的作用

杨利霞

2 O  n2 h# `( h6 y. |AM真菌在生态系统中的作用

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Forests accumulate and store large amounts of carbon (C), and a sub
8 m" t/ g4 e( c5 {- ~$ t( zstantial fraction of this stock is contained in deadwood. This transient pool is subject
5 k! {# ^4 }$ Vto decomposition by deadwood-associated organisms, and in this process it contrib
utes to CO2
emissions. Although fungi and bacteria are known to colonize dead
( a  E" A6 z- W& m8 |wood, little is known about the microbial processes that mediate carbon and nitro
gen (N) cycling in deadwood. In this study, using a combination of metagenomics,
& q2 U* |: [1 l' G4 m4 s; \; wmetatranscriptomics, and nutrient flflux measurements, we demonstrate that the decom
" C, c! Q, c. X/ E8 bposition of deadwood reflflects the complementary roles played by fungi and bacteria.
Fungi were found to dominate the decomposition of deadwood and particularly its re
. k7 ?, e9 A. E) E- s3 S' Ecalcitrant fractions, while several bacterial taxa participate in N accumulation in dead
# q/ ]+ i  H% m0 U& U0 Y0 Rwood through N fifixation, being dependent on fungal activity with respect to deadwood
colonization and C supply. Conversely, bacterial N fifixation helps to decrease the con
" b  L4 i7 |% g0 rstraints of deadwood decomposition for fungi. Both the CO2 efflflux and N accumulation
: W) \& A, P8 S1 ]5 i; j8 C7 Lthat are a result of a joint action of deadwood bacteria and fungi may be signifificant for
nutrient 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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