Dissertation Research: Impact of Differential Leaf Decomposition Rates and Invertebrate Shredders on Stream Nutrient Uptake Length

养分吸收长度，即营养原子在被生物或非生物从溶液中移除之前所走的距离，提供了溪流保持的指数，因此与产量和效率有关。以往的研究发现，河流中颗粒有机物(CPOM)的数量与养分吸收长度之间存在负相关关系。假设除了CPOM的数量外，微生物的定植模式和CPOM的分解率也是调节摄取长度的重要因素。这一假设将通过建造9条人工溪流和进行两个6-8个月的实验来检验。在实验1中，将使用三种不同微生物定植模式和破碎率的叶片类型。将在每条溪流中放置一种树叶类型(每种树叶类型重复三次)，并将在几个月内每两周测量一次养分吸收长度。在实验2中，将在每条溪流中放置不同类型的树叶。切碎叶子的无脊椎动物将被放置在一些溪流中，并被排除在其他溪流之外，以确定撕碎如何通过影响微生物活动和分解率来影响养分吸收。实验室实验将与实地工作同时进行，以确定生物和非生物吸收的相对重要性。

Nutrient uptake length, the distance traveled by a nutrient atom before being biotically or abiotically removed from solution, provides an index of stream retention and therefore has implications concerning production and efficiency. Previous studies found an inverse relationship between quantity of course particulate organic matter (CPOM) in the stream and nutrient uptake length. It is hypothesized that in addition to CPOM quantity, microbial colonization patterns and breakdown rates of CPOM are also important in regulating uptake length. This hypothesis will be tested by constructing nine artificial streams and conducting two 6-8 month long experiments. In experiment 1, three leaf types with different microbial colonization patterns and breakdown rates will be used. One leaf type will be placed in each stream (three replicates of each leaf type) and nutrient uptake length will be measured biweekly for several months. In experiment 2, a mixture of leaf types will be placed in each stream. Leaf shredding invertebrates will be placed in some streams and excluded from others to determine how shredding affects nutrient uptake through its impact on microbial activity and breakdown rates. A lab experiment will be done concurrent with field work to determine the relative importance of biotic and abiotic uptake.