Griffith Michael B, Perry Sue A, Perry William B
ICF Kaiser Engineers, 4 Gateway Center, 15222-1207, Pittsburgh, PA, USA.
National Biological Service, West Virginia Cooperative Fish and Wildlife Research Unit, West, Virginia University, 26506-6125, Morgantown, WV, USA.
Oecologia. 1995 Jun;102(4):460-466. doi: 10.1007/BF00341358.
We examined microbial colonization, exoenzyme activity, and processing of leaves of yellow poplar (Liriodendron tulipifera), red maple (Acer rubrum), and white oak (Quercus alba) in three streams on the Allegheny Plateau of West Virginia, United States. Leaf packs were placed in streams that varied in their underlying bedrock geology, and therefore in their sensitivity to the high level of acidic precipitation that occurs in this region. The mean pH of the streams was 4.3 in the South Fork of Red Run (SFR), 6.2 in Wilson Hollow Run (WHR), and 7.7 in the North Fork of Hickman Slide Run (HSR). Through time, the patterns of microbial biomass and exoenzyme activity were generally similar among leaf species, but the magnitude of microbial biomass and exoenzyme activity differed among leaf species. Pectinase activity was greatest in HSR, the most alkaline stream, whereas the activity of exocellulase and xylanase was greatest in WHR and SFR, the intermediate and acidic streams. This variation in the activity of different exoenzymes was consistent with published pH optima for these exoenzymes. Variation in processing rates, both among leaf species and among streams, seems to be related to the level of microbial exoenzyme activity on the leaf detritus.
我们在美国西弗吉尼亚州阿勒格尼高原的三条溪流中，研究了黄杨（鹅掌楸）、红枫（红花槭）和白栎（白栎）叶片的微生物定殖、胞外酶活性及分解情况。将叶片包放置在基岩地质不同的溪流中，因此这些溪流对该地区高酸性降水的敏感程度也不同。红径南支流（SFR）的溪流平均pH值为4.3，威尔逊谷溪（WHR）为6.2，希克曼滑坡溪北支流（HSR）为7.7。随着时间推移，不同叶片种类间微生物生物量和胞外酶活性的模式总体相似，但微生物生物量和胞外酶活性的大小在不同叶片种类间存在差异。果胶酶活性在碱性最强的HSR中最高，而外切纤维素酶和木聚糖酶活性在中等酸性的WHR和酸性的SFR中最高。不同胞外酶活性的这种变化与已发表的这些酶的最适pH值一致。叶片种类间和溪流间分解速率的差异，似乎与叶片碎屑上微生物胞外酶活性水平有关。
