AM真菌在生态系统中的作用

杨利霞

6 g' I+ J$ n. \4 ^' ]0 t; q9 H, X! JAM真菌在生态系统中的作用
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Forests 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
: l6 V, J0 j7 b( f, g& tto decomposition by deadwood-associated organisms, and in this process it contrib
& }! {  F  f+ A, g( xutes to CO2
$ }: g( n4 N3 C# H2 {# [' Demissions. Although fungi and bacteria are known to colonize dead
) \5 o/ _. [  p/ o0 E) jwood, little is known about the microbial processes that mediate carbon and nitro
/ Y. \- X* X7 c! s" Cgen (N) cycling in deadwood. In this study, using a combination of metagenomics,
metatranscriptomics, and nutrient flflux measurements, we demonstrate that the decom
position of deadwood reflflects the complementary roles played by fungi and bacteria.
# d+ E* R5 |$ ?4 Z: l; T6 m+ U, J5 OFungi were found to dominate the decomposition of deadwood and particularly its re
calcitrant fractions, while several bacterial taxa participate in N accumulation in dead
' q3 q3 P5 {, ]5 Swood through N fifixation, being dependent on fungal activity with respect to deadwood
/ _: c5 ?  M, K, B' ?, K3 Kcolonization 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
wood retention may help to improve the nutritional status and fertility of soils.
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