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




/ w2 ^8 d  c4 E# F  ~* n3 s6 }Forests accumulate and store large amounts of carbon (C), and a sub
8 W1 A3 s2 W3 j( D$ A# W( tstantial fraction of this stock is contained in deadwood. This transient pool is subject
7 A; g" E! Z7 Dto decomposition by deadwood-associated organisms, and in this process it contrib
# r' r  l0 [$ Y; K1 z) t& s5 Nutes to CO2
1 b5 o4 B8 i4 k, w+ oemissions. Although fungi and bacteria are known to colonize dead
9 }; G$ A. `" X/ \1 w' K3 kwood, little is known about the microbial processes that mediate carbon and nitro
' F7 T; V1 J7 v# lgen (N) cycling in deadwood. In this study, using a combination of metagenomics,
metatranscriptomics, and nutrient flflux measurements, we demonstrate that the decom
/ G  ^( w0 |* k. e7 xposition of deadwood reflflects the complementary roles played by fungi and bacteria.
Fungi were found to dominate the decomposition of deadwood and particularly its re
. ~% `( R4 ^5 y0 z% M, c, ^calcitrant 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
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
7 X: y9 i! l; Q$ y& snutrient cycling at ecosystem levels. Especially in boreal forests with low N stocks, dead
6 r1 x% T1 A" I# w$ L  J0 h  B$ bwood retention may help to improve the nutritional status and fertility of soils.
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, t  d+ i2 N) [- ~% e
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