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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( ^* G! l# r) U8 uForests accumulate and store large amounts of carbon (C), and a sub
4 y  F% p( O, q: Q& estantial fraction of this stock is contained in deadwood. This transient pool is subject
to decomposition by deadwood-associated organisms, and in this process it contrib
, x# ]2 C. S5 C# Z3 {$ \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
2 w4 V0 x6 D3 b% s, [gen (N) cycling in deadwood. In this study, using a combination of metagenomics,
& B- b  x; W  I! E; g4 Xmetatranscriptomics, and nutrient flflux measurements, we demonstrate that the decom
) _% i. r6 E$ z) |2 A: e8 gposition of deadwood reflflects the complementary roles played by fungi and bacteria.
Fungi were found to dominate the decomposition of deadwood and particularly its re
( E% l! d! I0 C: k" 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
% J& p/ S* m5 t1 e' l& Acolonization and C supply. Conversely, bacterial N fifixation helps to decrease the con
straints 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
nutrient cycling at ecosystem levels. Especially in boreal forests with low N stocks, dead
0 P; U  f7 P! c1 y: @wood retention may help to improve the nutritional status and fertility of soils.
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