分解程度の異なる樹種別リターの炭素および窒素無機化特性  [in Japanese] Nitrogen and Carbon Mineralization Characteristics of Different Decomposition Stages in Forest Floor of Some Tree Species  [in Japanese]

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Abstract

ケヤキ,ミズナラ,スギ,ヒノキ,アカマツの優占する林地においてA_0層(L-F_1,F_2,F_3,HA画分)および鉱物土壌層0〜5cm(A(0-5))の化学的性質,微生物バイオマスおよび炭素(C),窒素(N)の無機化量(25℃,30日間培養)を調査し,リターの分解に伴う化学的性質およびCとNの無機化パターンの変化と,それらを担う微生物との関わりについて考察した.1)A_0層の全N濃度はケヤキ>ミズナラ>スギ>ヒノキ>アカマツの順に高く,リターフォールの全N濃度の傾向と同じであった.2)水溶性有機態C(WSOC)濃度はL-F_1画分で最も高く,広葉樹のケヤキとミズナラでは針葉樹である他の3試験区の3倍であった.WSOC濃度は,分解の進行に伴い急速に低下した.3)微生物バイオマスC(MBC)濃度および微生物バイオマスN(MBN)濃度は,F_2画分またはF_3画分で最も高かった.4)C無機化量の最大となる画分は樹種によって異なり,L-F_1〜F_3画分であった.WSOC濃度とC無機化量との間に,HA画分およびA(0-5)では強い正の相関性が認められた.5)N無機化量は,F_3画分以降で最大となった.ミズナラでは硝化活性が著しく低かった.適潤性土壌のケヤキとスギでは,他の試験区より高いC/Nで純N無機化が生じた.6)分解の進行に伴うMBN濃度の増減が,全N濃度やN無機化量の増減よりも先行するヒステリシスが認められた.

Five experimental plots were set up in forest dominated by keyaki (Zelkova serrata), mizunara (Quercus mongolica var. grosseserrata), sugi (Cryptomeria japonica), hinoki (Chmaecyparis obutsa), and akamatsu (Pinusdensiflora) tree species. Forest floor samples were divided into L-F_1, F_2, F_3 and HA classes depending on the decomposition stages. Chemical properties and microbial biomass of carbon and nitrogen (MBC and MBN) in each class and mineral soil at the depth of 0-5 cm (A(0-5)) were measured. Mineralized carbon (C) and nitrogen (N) content of them for a 30-d incubation period at 25℃ were investigated. From these results, we discussed the relationships among them and the role of microbes in C and N mineralization in different decomposition stages in forest floor. 1) The order of total N concentration in forest floor was keyaki>mizunara>sugi>hinoki>akamatsu. It showed the same tendency as in litterfall. 2) Water soluble organic C (WSOC) concentration was the highest in L-F_1 class, and in keyaki and mizunara, it was three times as high as that of other three plots. It sharply decreased as decomposition of litter advanced. 3) In every plot, MBC and MBN concentrations were higher in F_2 and F_2 classes than in HA class and A(0-5). 4) The amounts of mineralized C were the greatest in L-F_1, F_2 or F_3 classes, with the ranking differing from plot to plot. The relationships between WSOC and mineralized C had a strong positive correlation in HA class and A(0-5). 5) The amounts of mineralized N were the greatest in F_3, HA classes or A(0-5) in every plot. In the mizunara plot, the nitrification rate was lower than in other plots. The net N mineralization in keyaki and sugi plots of moderately moist soil started under a higher C/N ratio than in other plots with dry soil. 6) Histerisis was shown, in which the increase or decrease of MBN concentration with the advancement of decomposition stage of litter preceded the increase or decrease of total N concentration and the amount of mineralized N.

Journal

  • Japanese Journal of Soil Science and Plant Nutrition

    Japanese Journal of Soil Science and Plant Nutrition 73(4), 363-372, 2002

    Japanese Society of Soil Science and Plant Nutrition

References:  30

Cited by:  6

Codes

  • NII Article ID (NAID)
    110001746619
  • NII NACSIS-CAT ID (NCID)
    AN00195767
  • Text Lang
    JPN
  • Article Type
    Journal Article
  • ISSN
    0029-0610
  • NDL Article ID
    6254776
  • NDL Source Classification
    ZR7(科学技術--農林水産--農産)
  • NDL Call No.
    Z18-331
  • Data Source
    CJP  CJPref  NDL  NII-ELS  J-STAGE  JASI 
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