Brant Justin B, Myrold David D, Sulzman Elizabeth W
Department of Crop and Soil Science, Oregon State University, Corvallis, OR 97331-7306, USA.
Oecologia. 2006 Jul;148(4):650-9. doi: 10.1007/s00442-006-0402-7. Epub 2006 Mar 18.
We assessed microbial community composition as a function of altered above- and belowground inputs to soil in forest ecosystems of Oregon, Pennsylvania, and Hungary as part of a larger Detritus Input and Removal Treatment (DIRT) experiment. DIRT plots, which include root trenching, aboveground litter exclusion, and doubling of litter inputs, have been established in forested ecosystems in the US and Europe that vary with respect to dominant tree species, soil C content, N deposition rate, and soil type. This study used phospholipid fatty-acid (PLFA) analysis to examine changes in the soil microbial community size and composition in the mineral soil (0-10 cm) as a result of the DIRT treatments. At all sites, the PLFA profiles from the plots without roots were significantly different from all other treatments. PLFA analysis showed that the rootless plots generally contained larger quantities of actinomycete biomarkers and lower amounts of fungal biomarkers. At one of the sites in an old-growth coniferous forest, seasonal changes in PLFA profiles were also examined. Seasonal differences in soil microbial community composition were greater than treatment differences. Throughout the year, treatments without roots continued to have a different microbial community composition than the treatments with roots, although the specific PLFA biomarkers responsible for these differences varied by season. These data provide direct evidence that root C inputs exert a large control on microbial community composition in the three forested ecosystems studied.
作为一项更大规模的碎屑输入与去除处理（DIRT）实验的一部分，我们评估了俄勒冈州、宾夕法尼亚州和匈牙利森林生态系统中土壤微生物群落组成随地上和地下输入土壤物质变化的情况。DIRT样地包括根系切断、地上凋落物排除以及凋落物输入加倍，已在美国和欧洲的森林生态系统中设立，这些生态系统在优势树种、土壤碳含量、氮沉降速率和土壤类型方面存在差异。本研究采用磷脂脂肪酸（PLFA）分析方法，以检验DIRT处理对矿质土壤（0 - 10厘米）中土壤微生物群落大小和组成的影响。在所有地点，无根样地的PLFA图谱与所有其他处理显著不同。PLFA分析表明，无根样地通常含有更多的放线菌生物标志物和更少的真菌生物标志物。在一片老龄针叶林的一个地点，还研究了PLFA图谱的季节性变化。土壤微生物群落组成的季节差异大于处理差异。全年来看，无根处理的微生物群落组成与有根处理不同，尽管导致这些差异的具体PLFA生物标志物随季节变化。这些数据提供了直接证据，表明根系碳输入对所研究的三个森林生态系统中的微生物群落组成具有很大的控制作用。
