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

微元素锰对针叶原木碳氮长期动态的控制本研究将验证针叶原木碳氮长期动态受微量元素锰有效性控制的假说。最近的研究表明，木质素的一个主要降解途径是由涉及锰的氧化反应控制的。先前的研究表明，针叶树木材中的初始锰浓度存在显著差异，这些差异对应于易受褐腐病(木质素很少降解)和易受白腐病(木质素和纤维素分解)影响的树种。由于木质素约占原始针叶木材的三分之一，因此所遵循的分解途径类型控制着长期碳贮量。因此，这项研究对于理解粗木质碎屑(CWD)在全球碳储存中的作用具有直接意义。Harmon，Jarrell和Caldwell假设：1)碳和氮动态的早期变化受分解者定植模式的控制，2)长期碳动态受微量元素锰的有效性控制，而锰在一定程度上决定了木质素是否分解，3)氮动态受有效碳的丰度而不是总碳的控制。为了验证这些假说，研究人员将进行一项为期三年的碳和氮动态研究，检查木材细胞壁化学、锰的有效性、微生物生理和生化、氮动态以及来自不同针叶生态系统的原木分解过程中质量损失的变化。他们还将继续开发一种分解模型，预测许多种类和大小的原木的长期碳和氮动态。Harmon、Jarrell和Caldwell是木质碎片在森林生态系统中的作用的创新和富有成效的调查人员。他们是俄勒冈州立大学杰出的林业研究团队的一部分。

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.