The Control of Long-term Carbon and Nitrogen Dynamics in Conifer Logs by the Microelement Manganese

微量元素锰对针叶树原木长期碳氮动态的控制本研究将验证微量元素锰的有效性控制针叶树原木长期碳氮动态的假设。近年来的研究表明木质素降解的一个主要途径是受锰氧化反应的控制。先前的研究揭示了针叶树木材中初始Mn浓度的显著差异，这些差异对应于易患褐腐病（木质素降解少）和易患白腐病（木质素和纤维素分解）的物种。由于木质素约占原始针叶树木材的三分之一，因此所遵循的分解途径类型控制了长期碳储存量。因此，本研究将对理解粗木屑（CWD）在全球碳储量中的作用具有直接意义。哈蒙、贾雷尔和考德威尔假设：1)早期碳氮动态变化受分解者定殖模式控制；2)长期碳动态受微量元素Mn的有效性控制，Mn在一定程度上决定木质素是否被分解；3)氮动态受有效碳丰度而非总碳丰度控制。为了验证这些假设，研究人员将进行一项为期三年的碳氮动力学研究，研究木材细胞壁化学、锰可用性、微生物生理学和生物化学、氮动力学和不同针叶生态系统中分解原木的质量损失的变化。他们还将继续开发分解模型，以预测许多物种和大小的原木的长期碳和氮动态。哈蒙、贾雷尔和考德威尔是研究森林生态系统中木质碎片作用的创新和富有成效的研究者。他们是俄勒冈州立大学杰出林业研究团队的成员。

THE CONTROL OF LONG-TERM CARBON AND NITROGEN DYNAMICS IN CONIFER LOGS BY THE MICROELEMENT MANGANESE This research will test the hypothesis that the long-term carbon and nitrogen dynamics of conifer logs is controlled by the availability of the microelement manganese. Recent research has revealed that a major lignin degradative pathway is controlled by oxidative reactions involving Mn. Prior research has revealed marked differences in the initial Mn concentrations in conifer wood, and these differences correspond to species susceptible to brown-rot (little lignin degraded) versus those susceptible to white-rot (lignin and cellulose breakdown). Since lignin comprises approximately one-third of the original conifer wood, the type of decomposition pathway followed controls the amount of long-term carbon storage. Therefore, this research will have direct implications for understanding the role of coarse woody debris (CWD) in global carbon storage. Harmon, Jarrell and Caldwell hypothesize that: 1) early changes in carbon and nitrogen dynamics are controlled by decomposer colonization patterns, 2) long-term carbon dynamics are controlled by the availability of the microelement Mn which determines, in part, whether lignin is decomposed, and 3) nitrogen dynamics are controlled by the abundance of available carbon and not total carbon. To test these hypotheses the investigators will conduct a three year study of carbon and nitrogen dynamics that examines changes in wood cell wall chemistry, manganese availability, microbial physiology and biochemistry, nitrogen dynamics and mass losses in decomposing logs from different coniferous ecosystems. They will also continue development of a decomposition model that predicts long- term carbon and nitrogen dynamics for many species and sizes of logs. Harmon, Jarrell and Caldwell are innovative and productive investigators of the role of woody debris in forested ecosystems. The are part of the outstanding team of forestry researchers at Oregon State University.