7 @3 ^0 e# y/ W5 Z/ n& aAM真菌在生态系统中的作用- `1 I' L T8 R$ ~3 G! b5 t
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+ }- Z/ [; p' I, h; V) ]$ BForests accumulate and store large amounts of carbon (C), and a sub, F* i4 N, j) }. l+ |. Z
stantial fraction of this stock is contained in deadwood. This transient pool is subject! j2 O. `2 H7 Y& B8 u
to decomposition by deadwood-associated organisms, and in this process it contrib ; @9 { N) ]" T" c+ w y% jutes to CO2 0 ]- t% o, g, \: ~: s, Z. O% Qemissions. Although fungi and bacteria are known to colonize dead2 f4 w# d; k; T7 u2 B
wood, little is known about the microbial processes that mediate carbon and nitro / E6 Y% K/ q2 p+ s# egen (N) cycling in deadwood. In this study, using a combination of metagenomics, - l, f6 \" A" }8 K: xmetatranscriptomics, and nutrient flflux measurements, we demonstrate that the decom+ A& Q+ L/ d5 L. k+ p; `
position of deadwood reflflects the complementary roles played by fungi and bacteria.8 d$ I% @! \2 D$ C2 {0 Q( m$ }" F
Fungi were found to dominate the decomposition of deadwood and particularly its re - z/ n3 I# ~- s8 k$ b& V3 Jcalcitrant fractions, while several bacterial taxa participate in N accumulation in dead1 m ]0 G: k* r$ \& q8 V9 S' n
wood through N fifixation, being dependent on fungal activity with respect to deadwood3 ]9 _2 n4 O5 q0 g
colonization and C supply. Conversely, bacterial N fifixation helps to decrease the con " N. d: H- j) _; {. { b. o" y2 Q+ rstraints of deadwood decomposition for fungi. Both the CO2 efflflux and N accumulation . [0 o# g% H. P( pthat are a result of a joint action of deadwood bacteria and fungi may be signifificant for3 h! I0 }" q1 M' v8 {8 ~; k
nutrient cycling at ecosystem levels. Especially in boreal forests with low N stocks, dead , Q: }4 T5 @. w& K' \* x; [0 gwood retention may help to improve the nutritional status and fertility of soils.0 ^8 x7 Y9 ` u g( O
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