AM真菌在生态系统中的作用

杨利霞

" U; o0 W& J  Z: x8 D. GAM真菌在生态系统中的作用
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9 f! Y( T: N& {# m' F3 O) MForests accumulate and store large amounts of carbon (C), and a sub
7 W# H3 U# S4 b  }5 k0 [stantial fraction of this stock is contained in deadwood. This transient pool is subject
5 D+ e9 Y" j+ y. A8 f) f  ^4 Nto decomposition by deadwood-associated organisms, and in this process it contrib
utes to CO2
emissions. Although fungi and bacteria are known to colonize dead
# F- H( q0 }7 [$ I3 u) Twood, little is known about the microbial processes that mediate carbon and nitro
. w3 o1 r1 V) ^# M2 y. Wgen (N) cycling in deadwood. In this study, using a combination of metagenomics,
metatranscriptomics, and nutrient flflux measurements, we demonstrate that the decom
; B& \& K: `- K9 l5 j% ]position of deadwood reflflects the complementary roles played by fungi and bacteria.
6 ?2 y" K; W% z" [. B. VFungi were found to dominate the decomposition of deadwood and particularly its re
+ ]4 w& N1 D/ S1 B: i6 y. ~- ~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
/ F) _( z' o& |' u) ?" n& hnutrient cycling at ecosystem levels. Especially in boreal forests with low N stocks, dead
4 [  }8 ^4 k- qwood retention may help to improve the nutritional status and fertility of soils.
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