Nutrient input and carbon and microbial dynamics in an ombrotrophic bog
Nutrient input and carbon and microbial dynamics in an ombrotrophic bog
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DOI：
10.1080/01490450600897278
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发表时间：
2006-10-01
影响因子：
2.3
通讯作者：
Bubier, Jill L.
中科院分区：
文献类型：
--
作者：
Basiliko, Nathan;Moore, Tim R.;Bubier, Jill L.
营养丰富的沼泽中植物生产和分解的缓慢速度被认为部分是由于养分利用率低造成的。为了测试养分有效性对分解、二氧化碳(CO2)通量动态、微生物生物量和养分的影响，我们在加拿大安大略省Mer Bleue泥炭地的两个生长季节内，添加了氮(N)、磷(P)和钾(K)，以防止后两种养分的限制。在第一个生长季节后，增加氮肥(在固定P和K的情况下)降低了泥炭上层用氯仿熏蒸-提取技术测得的体外CO2产生潜力，增加了微生物生物量，而到第二个生长季节结束时，CO2产生潜力随着N+PK处理的增加而增加，这可能是由于更容易分解的新形成的植物物质所致。在第二年使用小室技术测量的现场二氧化碳通量证实了这一假设，在高N+PK处理期间，光合作用CO2吸收和生态系统呼吸(ER)更大。第一年后，更有效的微生物群落具有更慢的二氧化碳产生潜力和更大的生物量，其特征是用标志性磷脂脂肪酸测量的真菌生物量更大。大部分N可能被植被迅速隔离并转移到泥炭剖面上部的溶解有机形态和微生物生物量中，而相对于对照的额外P分布在整个剖面上，这意味着该地点的植被N是有限的。然而，现场的CO2通量数据表明了P或NPK限制的可能性。我们假设，营养沉积可能通过改变微生物群落和分解导致碳吸收增强，但这种模式随着植被和更容易分解的植物组织的产生的随后变化而消失。
Slow rates of plant production and decomposition in ombrotrophic bogs are believed to be partially the result of low nutrient availability. To test the effect of nutrient availability on decomposition, carbon dioxide ( CO2) flux dynamics, microbial biomass, and nutrients, we added nitrogen ( N) with phosphorus ( P) and potassium ( K), to prevent limitation of the latter 2 nutrients, over 2 growing seasons to plots at Mer Bleue peatland, Ontario, Canada. After the first growing season, increasing N fertilization ( with constant P and K) decreased in vitro CO2 production potential and increased microbial biomass measured with a chloroform fumigation- extraction technique in the upper peat profile, while by the end of the second season, CO2 production potential was increased in response to N plus PK treatment, presumably due to more easily decomposable newly formed plant material. In situ CO2 fluxes measured using chamber-techniques over the second year corroborated this presumption, with greater photosynthetic CO2 uptake and ecosystem respiration ( ER) during high N plus PK treatments. The more efficient microbial community, with slower CO2 production potential and larger biomass, after the first year was characterized by larger fungal biomass measured with signature phospholipid fatty acids. The majority of N was likely quickly sequestered by the vegetation and transferred to dissolved organic forms and microbial biomass in the upper parts of the peat profile, while additional P relative to controls was distributed throughout the profile, implying that the vegetation at the site was N limited. However, in situ CO2 flux data suggested the possibility of P or NPK limitation. We hypothesize that nutrient deposition may lead to enhanced C uptake by altering the microbial community and decomposition, however this pattern disappears through subsequent changes in the vegetation and production of more readily decomposable plant tissues.