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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5 u" Q1 ?" }* sForests 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
9 P6 h. q2 ?. o7 \5 k# f3 j* ^to decomposition by deadwood-associated organisms, and in this process it contrib
utes to CO2
emissions. Although fungi and bacteria are known to colonize dead
# i$ Q  R) C& v2 j; Qwood, little is known about the microbial processes that mediate carbon and nitro
gen (N) cycling in deadwood. In this study, using a combination of metagenomics,
7 |; ~% V' B+ Z6 @6 e" rmetatranscriptomics, and nutrient flflux measurements, we demonstrate that the decom
: d5 G! O# U/ s3 \/ oposition of deadwood reflflects the complementary roles played by fungi and bacteria.
' @. J" U9 o" s$ v; mFungi were found to dominate the decomposition of deadwood and particularly its re
- E8 k4 {  c# W+ r: W0 Y6 |calcitrant fractions, while several bacterial taxa participate in N accumulation in dead
# k5 q9 W3 M% A4 J: X0 awood 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
& B! N+ Q; u7 I) h$ fthat 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
wood retention may help to improve the nutritional status and fertility of soils.


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