Abiotic Lignin Degradation: The Key to Litter Transformation after Forest Disturbance?

非生物木质素降解：森林扰动后凋落物转化的关键？

• 批准号: 501469439
• 负责人: Professor Dr. Bruno Glaser
• 金额: --
• 依托单位: Professur für Bodenökologie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/501469439?language=en
• 关键词: Abiotic; Lignin; Degradation; Key; Litter

Disturbances such as drought and storm events that cause canopy cover loss alter microclimatic conditions that in turn influence litter transformation and carbon cycling in forest ecosystems. A major bottleneck to litter transformation is lignin, which is degraded by abiotic effectors such as light and heat in addition to microorganisms. In disturbed forest ecosystems of Central Europe, the quantity and quality of soil organic matter can be strongly impacted by abiotic degradation of lignin and its synergistic effects on litter decomposition. However, little is known about this so far. To identify and quantify canopy cover controls of litter transformation matter after forest disturbance, we will test the following hypotheses: (H1) Abiotic lignin degradation increases more with light irradiance than heat and moisture deficits. (H2) Abiotic lignin degradation produces compounds more depolymerized than products of brown rot and with less oxygen functional groups than products of white rot. (H3) Abiotic lignin degradation alleviates fungal bottlenecks to bacterial degradation of litter in the forest floor, and thus favors enrichment of dissolved organic matter with depolymerized and de-oxygenated lignin compounds in the forest floor. (H4) Therefore, when canopy cover is lost, enhanced light irradiance and corresponding abiotic depolymerization and de-oxygenation of lignin in the forest floor renders organic matter entering mineral soil less available to microorganisms and less reactive to minerals. We will test these hypotheses first for model substances and litter of Norway spruce and European beech in laboratory incubations under controlled microbial, light, moisture and temperature conditions in order to determine abiotic lignin degradation rates and corresponding byproducts by water extracts, cupric-oxide oxidation and X-ray photoelectron spectroscopy. In the same incubations, fungal and bacterial response to abiotic degradation will be determined through via analysis of decay type, phospholipid fatty acids and microbial carbon, nitrogen and phosphorus. In mixed spruce stands along a disturbance gradient in the Black Forest National Park, we will assess in-situ transformation of 13C-labelled beech litter. During a simultaneous two-year inventory in the same mixed spruce stands, indicators of abiotic degradation as well as the reactivity and stability of soil organic matter will be measured. The combined results of our project will enable abiotic lignin degradation to be quantified and thus deliver essential insights into its relevance to the formation and stability of soil organic matter in disturbed forest stands.

诸如干旱和风暴事件之类的干旱覆盖损失会改变微气候条件，从而影响垃圾转化和森林生态系统中的碳循环。木质素是垃圾转化的主要瓶颈，木质素除了微生物之外，还被光和热量等非生物效应子降解。在中欧的森林生态系统受到干扰，土壤有机物的数量和质量可能会受到木质素的非生物降解及其对垃圾分解的协同作用的影响。但是，到目前为止，对此知之甚少。为了识别和量化森林干扰后垃圾转化物质的控制冠层的控制，我们将测试以下假设：（H1）非生物木质素降解随光辐照度而不是热和水分缺陷而增加。 （H2）与棕色腐烂的产物相比，非生物木质素降解产生的化合物比白色腐烂产物更少，氧官能团更少。 （H3）非生物木质素降解减轻了真菌瓶颈，从而使森林地面中的垃圾降解，因此有利于溶解有机物的富集，并在森林层中使用降低和去氧化的木质素化合物。 （H4）因此，当冠层覆盖层丢失时，林地底木质素的相应的光辐照度和相应的非生物解聚和相应的非生物解聚和脱氧，使有机物有机物进入矿物质土壤，对微生物的可用性较低，对矿物质的反应较低。我们将首先在受控的微生物，光，水分和温度条件下在实验室中孵育的挪威云杉和欧洲山毛榉的模型物质和垃圾，以确定非生物性木质素降解速率以及水提取物，铜氧化物氧化和氧化物氧化和氧化物氧化和氧化物氧化和相应的副产品。 X射线光电子光谱。在相同的孵育中，将通过分析衰减类型，磷脂脂肪酸和微生物碳，氮和磷来确定对非生物降解的真菌和细菌反应。在黑森林国家公园（Black Forest National Park）的干扰梯度上，在混合云杉架上，我们将评估13c标记的山毛榉垫料的原位转换。在同一混合云杉架上同时进行两年库存期间，将测量非生物降解的指标以及土壤有机物的反应性和稳定性。我们项目的综合结果将使非生物木质素降解能够进行量化，从而对其与森林干扰林的土壤有机物的形成和稳定性相关的基本见解。