Rapid decomposition of maize detritus in agricultural headwater streams
Rapid decomposition of maize detritus in agricultural headwater streams
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DOI：
10.1890/07-1876.1
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发表时间：
2009-01-01
影响因子：
5
通讯作者：
Evans-White, Michelle A.
中科院分区：
文献类型：
--
作者：
Griffiths, Natalie A.;Tank, Jennifer L.;Evans-White, Michelle A.
源头流排水农业景观接收玉米叶（玉米L.）玉米碎屑通过风和地表径流进入农田，但玉米碎屑对农业溪流中有机物加工的贡献在很大程度上是未知的。我们量化的分解和微生物呼吸速率对常规（非Bt）和转基因（Bt）玉米在三个低阶农业流在西北印第安纳州，美国。我们还研究了基质质量和流中营养浓度如何影响玉米上的微生物呼吸作用，通过比较三个营养丰富的农业流和三个低营养森林流中的玉米和红枫叶（红槭）的呼吸作用。我们发现玉米上的微生物呼吸速率显著高于红枫叶，农业溪流中的微生物呼吸速率高于森林溪流。因此，农业河流的营养状况和玉米碎屑的不稳定性（e。例如，在一个实施例中，低碳氮比和低木质素含量）导致玉米叶快速并入水生微生物食物网。我们发现，Bt玉米有一个更快的分解速度比非Bt玉米，而微生物呼吸速率之间没有差异。分解率没有受到基因工程的负面影响，也许是因为Bt毒素不会对参与玉米分解的水生微生物组合产生不利影响。此外，粉碎石蛾，这是已知的抑制生长速度时，喂养Bt玉米，在这些农业流depaerated，可能没有发挥主要作用，玉米分解。总体而言，原生植被的中耕农业的转换似乎已经改变了数量，质量和可预测性的外来碳输入源流，流生态系统的结构和功能的未开发的影响。
Headwater streams draining agricultural landscapes receive maize leaves (Zea mays L.) via wind and surface runoff, yet the contribution of maize detritus to organic-matter processing in agricultural streams is largely unknown. We quantified decomposition and microbial respiration rates on conventional (non-Bt) and genetically engineered (Bt) maize in three low-order agricultural streams in northwestern Indiana, USA. We also examined how substrate quality and in-stream nutrient concentrations influenced microbial respiration on maize by comparing respiration on maize and red maple leaves (Acer rubrum) in three nutrient-rich agricultural streams and three low-nutrient forested streams. We found significantly higher rates of microbial respiration on maize vs. red maple leaves and higher rates in agricultural vs. forested streams. Thus both the elevated nutrient status of agricultural streams and the lability of maize detritus (e. g., low carbon-to-nitrogen ratio and low lignin content) result in a rapid incorporation of maize leaves into the aquatic microbial food web. We found that Bt maize had a faster decomposition rate than non-Bt maize, while microbial respiration rates did not differ between Bt and non-Bt maize. Decomposition rates were not negatively affected by genetic engineering, perhaps because the Bt toxin does not adversely affect the aquatic microbial assemblage involved in maize decomposition. Additionally, shredding caddisflies, which are known to have suppressed growth rates when fed Bt maize, were depauperate in these agricultural streams, and likely did not play a major role in maize decomposition. Overall, the conversion of native vegetation to row-crop agriculture appears to have altered the quantity, quality, and predictability of allochthonous carbon inputs to headwater streams, with unexplored effects on stream ecosystem structure and function.