ENVIRONMENTAL-REGULATION OF NITROGEN-FIXATION IN A HIGH ARCTIC LOWLAND ECOSYSTEM
ENVIRONMENTAL-REGULATION OF NITROGEN-FIXATION IN A HIGH ARCTIC LOWLAND ECOSYSTEM
复制标题
DOI：
10.1139/b91-345
复制
发表时间：
1991-12-01
期刊：
影响因子：
--
通讯作者：
BLEDSOE, LJ
中科院分区：
文献类型：
--
作者：
CHAPIN, DM;BLISS, LC;BLEDSOE, LJ
本研究探讨了蓝藻固氮的时空变化和这种变化的环境调节在Truelove低地，德文郡岛，西北部。在1987年和1988年生长季节，在均匀的光温条件下，测定了不同植物群落土壤-植物芯的乙炔还原速率。同时测量土壤水分和可提取的氮和磷。温度，水分和磷的影响进行了研究，在操纵实验。乙炔还原率最高的半咸水环境中，中间的中位到氢的陆地和水生生物群落，和最低的干旱海滩山脊。价格一般在赛季初上升，然后下降，通过中期到后期。在三个参数检查，利率是最高度相关的土壤水分。固定的最佳温度接近20 ℃。有一个强大的，但可逆的，在乙炔还原实验干燥的抑郁症，每周磷肥固定率有很强的积极影响。最高的固定率沿着海洋海岸线与高磷输入海藻和更大的生物量的蓝藻。由于水分的压倒一切的重要性，氮和磷水平的变化，伴随着生态系统的发展似乎并没有强烈控制固氮在陆地，nonbrackish网站在这个极地沙漠绿洲。
This study examined spatial and temporal variation in cyanobacterial nitrogen fixation and the environmental regulation of this variation at Truelove Lowland, Devon Island, N.W.T. Acetylene reduction rates of soil-plant cores from a variety of plant communities were measured under uniform conditions of light and temperature during the 1987 and 1988 growing seasons. Concurrent measurements of soil moisture and extractable nitrogen and phosphorus were also made. Effects of temperature, moisture, and phosphorus were examined in manipulative experiments. Acetylene reduction rates were highest in brackish environments, intermediate in mesic to hydric terrestrial and in aquatic communities, and lowest on xeric beach ridges. Rates generally increased during early season, then decreased through mid to late season. Among the three parameters examined, rates were most highly correlated to soil moisture. The temperature optimum for fixation was near 20-degrees-C. There was a strong, but reversible, depression in acetylene reduction in response to experimental desiccation, and weekly phosphorus fertilization had a strong positive effect on fixation rates. The highest fixation rates along the marine shoreline were associated with high phosphorus input from marine algae and greater biomass of cyanobacteria. Because of the overriding importance of moisture, changes in nitrogen and phosphorus levels accompanying ecosystem development do not appear to strongly control nitrogen fixation in terrestrial, nonbrackish sites in this polar desert oasis.