COLLABORATIVE RESEARCH: Photodegredation in deserts: litter optical and structural considerations

碳循环模型用于评估未来碳政策情景将如何影响大气碳库和气候。这些模型的准确性取决于我们对碳循环主要途径的理解。其中一种途径，即死亡植物（凋落物）的腐烂，每年向大气中释放的碳比化石燃料的燃烧还要多。森林凋落物的凋落物衰减是相当容易理解的，但凋落物衰减的速度和时间模式在沙漠中是不同的。阳光直射对凋落物的影响可能会增加凋落物的腐烂速度，而缺乏水分会降低微生物的活性，降低凋落物的腐烂速度。该项目将测试荒漠植物凋落物的光学特性是否对凋落物腐烂的不同模式有贡献。实验室和实地试验将用于测试相对于其他机制（如微生物活动），阳光作为凋落物腐烂剂的重要性。这项研究将在索诺兰沙漠进行，将有助于我们了解沙漠和其他生态系统中的碳循环，在这些生态系统中，凋落物暴露在强烈的阳光下（例如草原和农业系统）。调查人员将建立一个网站，为K12学生提供凋落物分解指南，并提供一个辅助教师进行凋落物分解实验的同伴指南，并邀请K12教师参与该实验。该项目将为K12学生和教师、本科生和研究生提供研究经验。

Carbon cycle models are used to assess how future carbon policy scenarios will influence atmospheric carbon pools and climate. The accuracy of those models depends on our understanding of major pathways in the carbon cycle. One such pathway, the decay of dead plant material (litter), is responsible for releasing more carbon into the atmosphere each year than the combustion of fossil fuel. Litter decay in forests is reasonably well understood, but both the rate and temporal pattern of litter decay are different in deserts. The effects of direct sunlight on litter may increase the rate of decay, while the lack of moisture may reduce microbial activity and decrease the decay rate. This project will test whether the optical properties of litter produced by desert plants contribute to the different pattern of litter decay. Laboratory and field experiments will be used to test the importance of sunlight as an agent of litter decay relative to other mechanisms such as microbial activity. This research, which will be conducted in the Sonoran Desert, will contribute to our understanding of carbon cycling in deserts and in other ecosystems where litter is exposed to intense sunlight (e.g. grasslands and agricultural systems).The investigators will develop a website that contains a guide to litter decomposition for K12 students, a companion guide to aid teachers in conducting litter decomposition experiments, and they will solicit K12 teachers to take part in this experiment. This project will provide research experience for K12 students and teachers, and undergraduate and graduate students.