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AM真菌在生态系统中的作用 # k E/ d3 P$ u& {# j* b! N3 m' ?; d# l/ }0 i& G6 C" X
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Forests accumulate and store large amounts of carbon (C), and a sub 2 M; M& q+ m2 G) U' c/ B- rstantial fraction of this stock is contained in deadwood. This transient pool is subject ; r2 c* \( q6 W; T, z. K- Gto decomposition by deadwood-associated organisms, and in this process it contrib( w" g& l; H7 G4 [2 Y u
utes to CO2 : T9 ~9 j" ^7 j$ ]& K+ Y
emissions. Although fungi and bacteria are known to colonize dead- t" B$ R2 C, P( p- K, W
wood, little is known about the microbial processes that mediate carbon and nitro 1 d) W5 L0 t# m2 Fgen (N) cycling in deadwood. In this study, using a combination of metagenomics, ' U. a( n# \% P* {% Y9 ]metatranscriptomics, and nutrient flflux measurements, we demonstrate that the decom 4 ^5 E K* w" y9 tposition of deadwood reflflects the complementary roles played by fungi and bacteria.& |6 ^, W% R8 R
Fungi were found to dominate the decomposition of deadwood and particularly its re5 s8 m, A* A; L W2 I1 b. f
calcitrant fractions, while several bacterial taxa participate in N accumulation in dead ) B( U6 Q9 l6 a0 B7 X% c# n1 cwood through N fifixation, being dependent on fungal activity with respect to deadwood; ]- i& q6 Y8 A9 E3 o9 e; |2 i
colonization and C supply. Conversely, bacterial N fifixation helps to decrease the con + S P" ^/ O" L: |% b- p2 P3 f5 qstraints of deadwood decomposition for fungi. Both the CO2 efflflux and N accumulation 2 M0 S3 C9 x3 t4 Gthat are a result of a joint action of deadwood bacteria and fungi may be signifificant for 0 t# S/ Q+ l- b, y9 s$ e% Dnutrient cycling at ecosystem levels. Especially in boreal forests with low N stocks, dead 6 X/ M1 ]0 a4 Hwood retention may help to improve the nutritional status and fertility of soils. . U$ [! j) U9 ^6 x) [0 c) S$ ]1 y+ @' Q+ {
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