Fertilization effects on fineroot biomass, rhizosphere microbes and respiratory fluxes in hardwood forest soils.
Fertilization effects on fineroot biomass, rhizosphere microbes and respiratory fluxes in hardwood forest soils.
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DOI：
10.1111/j.1469-8137.2007.02204.x
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发表时间：
2007-11
期刊：
影响因子：
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通讯作者：
Richard P Phillips;T. Fahey
中科院分区：
文献类型：
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作者：
Richard P Phillips;T. Fahey
施肥引起的森林土壤中CO（2）通量（（F）CO（2））的减少以前被归因于根系碳分配的减少，以及由于氮抑制真菌活性而导致的分解减少。在这里，我们提出的证据表明，减少根际微生物呼吸也可能有助于（F）CO（2）减少施肥森林土壤。在65年生的北方红橡（Quercus rubra）和糖枫（Acer saccharum）人工林以及85年生的天然黄桦（Betula allegheniensis）林分中，施肥使（F）CO（2）降低了16-19%。在橡树小区中，施肥对细根生物量没有影响，但使菌根定殖降低了18%，微生物呼吸降低了43%。在枫树小区，施肥减少根生物量，菌根定植和微生物呼吸分别为22%，16%和46%。在白桦地块，施肥减少了36%的微生物呼吸，但根生物量和菌根定殖变量的影响。在所有三个物种的地块，施肥对微生物呼吸的影响是更大的根际比散装土壤，可能是由于这些物种在肥沃的土壤根际碳通量减少。由于根际过程可能会影响森林生态系统中的养分有效性和碳储存，因此需要进一步的研究来更好地量化根际微生物对（F）CO（2）的贡献。
Fertilizer-induced reductions in CO(2) flux from soil ((F)CO(2)) in forests have previously been attributed to decreased carbon allocation to roots, and decreased decomposition as a result of nitrogen suppression of fungal activity. Here, we present evidence that decreased microbial respiration in the rhizosphere may also contribute to (F)CO(2) reductions in fertilized forest soils. Fertilization reduced (F)CO(2) by 16-19% in 65-yr-old plantations of northern red oak (Quercus rubra) and sugar maple (Acer saccharum), and in a natural 85-yr-old yellow birch (Betula allegheniensis) stand. In oak plots, fertilization had no effects on fine root biomass but reduced mycorrhizal colonization by 18% and microbial respiration by 43%. In maple plots, fertilization reduced root biomass, mycorrhizal colonization and microbial respiration by 22, 16 and 46%, respectively. In birch plots, fertilization reduced microbial respiration by 36%, but had variable effects on root biomass and mycorrhizal colonization. In plots of all three species, fertilization effects on microbial respiration were greater in rhizosphere than in bulk soil, possibly as a result of decreased rhizosphere carbon flux from these species in fertile soils. Because rhizosphere processes may influence nutrient availability and carbon storage in forest ecosystems, future research is needed to better quantify rhizo-microbial contributions to (F)CO(2).