AM真菌在生态系统中的作用

杨利霞

, H$ f, ^' f! m: eAM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
stantial fraction of this stock is contained in deadwood. This transient pool is subject
& [: J. Z: J6 c0 nto decomposition by deadwood-associated organisms, and in this process it contrib
utes to CO2
emissions. Although fungi and bacteria are known to colonize dead
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,
" X: R. Q2 I3 q- t5 emetatranscriptomics, and nutrient flflux measurements, we demonstrate that the decom
7 P4 V2 @. U- ?  A" `position of deadwood reflflects the complementary roles played by fungi and bacteria.
Fungi were found to dominate the decomposition of deadwood and particularly its re
- j: W. v. o( w+ u% u$ Vcalcitrant fractions, while several bacterial taxa participate in N accumulation in dead
8 W. a! i7 p5 W" b2 Bwood through N fifixation, being dependent on fungal activity with respect to deadwood
1 W& v9 ?1 p0 H6 c& ?, z4 u: C) I3 k$ ccolonization and C supply. Conversely, bacterial N fifixation helps to decrease the con
8 u; k/ Z$ o% y- a* h  bstraints of deadwood decomposition for fungi. Both the CO2 efflflux and N accumulation
+ Z) g6 ~$ a3 G8 R" uthat are a result of a joint action of deadwood bacteria and fungi may be signifificant for
( I6 f; b* D1 H& Fnutrient cycling at ecosystem levels. Especially in boreal forests with low N stocks, dead
- l, t% g' n: _. m& W- O2 E8 E& i8 pwood retention may help to improve the nutritional status and fertility of soils.