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
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- s; _8 `! W( n" v/ U/ r6 FForests 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
. @* F0 @9 R5 D$ Gto decomposition by deadwood-associated organisms, and in this process it contrib
1 j+ t" K5 }! vutes to CO2
7 Q8 K8 M' g7 g: ]8 p) y( uemissions. Although fungi and bacteria are known to colonize dead
2 p5 x$ Z5 v% j: Y2 L! R1 [- Uwood, little is known about the microbial processes that mediate carbon and nitro
% {; C3 R) v: X7 c" |4 Cgen (N) cycling in deadwood. In this study, using a combination of metagenomics,
$ s, M, R7 E: q3 imetatranscriptomics, and nutrient flflux measurements, we demonstrate that the decom
+ M) J. E6 ?+ z$ T/ K+ t9 W, k# x& wposition of deadwood reflflects the complementary roles played by fungi and bacteria.
% U  J3 W/ D. {- a: `& `Fungi were found to dominate the decomposition of deadwood and particularly its re
" V2 D0 @2 I4 T+ [2 y' ]3 I5 scalcitrant fractions, while several bacterial taxa participate in N accumulation in dead
wood 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
. w% A% c9 Y7 I1 E; b2 O8 q/ Fstraints of deadwood decomposition for fungi. Both the CO2 efflflux and N accumulation
that are a result of a joint action of deadwood bacteria and fungi may be signifificant for
/ N( J+ I8 U/ e7 p3 R# D- D0 knutrient cycling at ecosystem levels. Especially in boreal forests with low N stocks, dead
8 U# }+ K8 O1 D, Nwood retention may help to improve the nutritional status and fertility of soils.

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