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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Forests accumulate and store large amounts of carbon (C), and a sub
% ]1 n$ p; J# d, t$ [stantial fraction of this stock is contained in deadwood. This transient pool is subject
( r' O) x- Q# c. lto decomposition by deadwood-associated organisms, and in this process it contrib
) e" {  c; b/ y1 ~8 _: y& Outes to CO2
& Q9 U( F) c% j! F# _emissions. Although fungi and bacteria are known to colonize dead
wood, little is known about the microbial processes that mediate carbon and nitro
/ c+ D( \, l4 ~3 N, }" N1 c5 d3 [$ `gen (N) cycling in deadwood. In this study, using a combination of metagenomics,
metatranscriptomics, and nutrient flflux measurements, we demonstrate that the decom
position of deadwood reflflects the complementary roles played by fungi and bacteria.
2 _. g! k9 \$ U; F3 x+ VFungi were found to dominate the decomposition of deadwood and particularly its re
calcitrant fractions, while several bacterial taxa participate in N accumulation in dead
0 G8 z! v5 e/ }wood through N fifixation, being dependent on fungal activity with respect to deadwood
- B0 {# h" h1 G' p( v' jcolonization and C supply. Conversely, bacterial N fifixation helps to decrease the con
3 R7 b; g% V  Y; }  C) \straints of deadwood decomposition for fungi. Both the CO2 efflflux and N accumulation
# V5 C7 c4 i: w. Z  c8 [that are a result of a joint action of deadwood bacteria and fungi may be signifificant for
0 E/ t, W" x0 V9 @nutrient cycling at ecosystem levels. Especially in boreal forests with low N stocks, dead
, Z1 p, s& d8 v/ t9 Z! j7 Jwood retention may help to improve the nutritional status and fertility of soils.

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