AM真菌在生态系统中的作用

杨利霞

7 @3 ^0 e# y/ W5 Z/ n& aAM真菌在生态系统中的作用


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+ }- Z/ [; p' I, h; V) ]$ BForests accumulate and store large amounts of carbon (C), and a sub
stantial 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
; @9 {  N) ]" T" c+ w  y% jutes to CO2
0 ]- t% o, g, \: ~: s, Z. O% Qemissions. Although fungi and bacteria are known to colonize dead
wood, little is known about the microbial processes that mediate carbon and nitro
/ E6 Y% K/ q2 p+ s# egen (N) cycling in deadwood. In this study, using a combination of metagenomics,
- l, f6 \" A" }8 K: xmetatranscriptomics, and nutrient flflux measurements, we demonstrate that the decom
position of deadwood reflflects the complementary roles played by fungi and bacteria.
Fungi were found to dominate the decomposition of deadwood and particularly its re
- z/ n3 I# ~- s8 k$ b& V3 Jcalcitrant 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
" N. d: H- j) _; {. {  b. o" y2 Q+ rstraints of deadwood decomposition for fungi. Both the CO2 efflflux and N accumulation
. [0 o# g% H. P( pthat 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
, Q: }4 T5 @. w& K' \* x; [0 gwood retention may help to improve the nutritional status and fertility of soils.