Dissertation Research: Why Does N-Limitation Occur in Some Arctic Lakes? Understanding Controls of N-Fixation

氮是所有动植物必需的营养物质，但它限制了许多北极湖泊的植物生长。北极在过去的30年里已经变暖了2度。这种变暖导致冻土融化，湖泊的氮输入增加。为了预测北极湖泊将如何应对气候变化，了解氮是如何控制植物生长的势在必行。尽管大气中80%的成分是氮，但大多数植物无法获得氮。只有特殊的细菌才能“固定”大气中的氮，并将其转化为植物可以利用的形式。如果这些细菌能足够快地固定氮，植物的生长就不会受到氮的限制。然而，固氮细菌并不能缓解北极湖泊中氮的短缺。这项研究的目的是研究温度、光、营养物质和食草动物如何相互作用来控制这些北极湖泊的固氮。

Nitrogen is an essential nutrient to all plants and animals, yet it limits plant growth in many arctic lakes. The Arctic has warmed 2 degrees in the last 30 years. This warming causes frozen ground to melt and nitrogen inputs to lake increase. It is imperative to understand how nitrogen controls plant growth in order to predict how arctic lakes will respond to climate change. Even though the atmosphere is 80% nitrogen, it is unavailable to most plants. Only specialized bacteria can "fix" atmospheric nitrogen and convert it into forms that are available to plants. If these bacteria can fix nitrogen fast enough, plant growth will not be nitrogen limited. However, nitrogen-fixing bacteria do not alleviate the shortage of nitrogen in arctic lakes. The goal of this study is to examine how temperature, light, nutrients, and grazers interact to control nitrogen fixation in these arctic lakes.