Fire-Induced Redistribution and Losses of Elements in the Weathering Zone (FIRE)

火是最重要的地貌因素之一--一种极端事件，导致元素形态的巨大变化，并在很短的时间内导致生态系统中营养物质和压舱元素的损失。频繁的火灾（半）干旱，地中海，甚至在森林生态系统中诱导的微生物动员和植被从腐泥土隆起的所有元素的戏剧性的重新分配。在第一阶段-微生物（主要是真菌）动员元素的根碳输入到土壤中，植物从土壤和腐泥土中吸收养分进行了研究。在第二阶段，将调查火灾和火灾后这些元素的损失以及对微生物群落和功能的影响。根据土壤中有效养分和压舱元素含量i）人工燃烧后和ii）自然火灾后生态系统恢复的时间序列，我们将得出短期和中期元素损失的结论。这些损失将被划分为淋溶和侵蚀的基础上的实验与示踪剂的N，K，Ca和Si。火灾对微生物群落和功能的致命影响将通过共生和腐生性真菌门和重氮营养生物，酶活性和PLFA组成的表土中的丰度来跟踪。火灾后恢复过程中的微生物演替将进行研究，特别强调耐应力和矿物风化真菌。真菌和细菌的功能作用将通过qPCR分析与高通量测序数据的比较得到支持。将特别关注真菌，因为在岩石表面和根/土壤界面的有氧条件下，真菌特别重要：应力保护的真菌细胞（i）与矿物质形成广泛的接触，并增强矿物质中营养物质的化学释放，（ii）加速火灾后土壤的酸化。土壤微生物群落的中短期演替与土壤酶活性、PLFA组成、养分迁移和积累的增加有关。从潘德阿苏卡尔到纳韦布塔的干旱梯度将阐明降水对火灾后营养物质和压舱元素的绝对和相对损失以及对生态系统恢复的影响。第一阶段的结果将用于概括稳定状态下的养分循环和风化输入-在依赖于气候的稳定生态系统中。第二阶段的结果将使人们能够概括极端事件-火灾-在微生物和植被演替过程中，在恢复的生态系统中，对元素的损失及其随后的风化积累产生的巨大影响。考虑到世界范围内日益增加的干旱化，因此火灾的频率，预计预测的营养物质和压载元素的生态系统和随后的风化损失具有全球意义。

Fire is one of the most important geomorphological factors – an extreme event leading to huge changes of the element speciation and subsequent losses of nutrients and ballast elements from ecosystems during a very short period. Frequent fires in (semi)arid, Mediterranean and even in forest ecosystems induce dramatic reallocation of all elements that microorganisms mobilized and vegetation uplifted from the saprolite. In the 1st phase – microbial (mainly fungal) mobilization of elements by root carbon input into the soil and uptake of nutrients by plants from the soil and saprolite were investigated. In the 2nd phase the losses of these elements by and after fires will be investigated in parallel with the effects on microbial communities and functions. Based on available nutrient and ballast element contents in soils i) after artificial burning and ii) chronosequences of ecosystems recoveries after natural fires, we will conclude about the element losses over short- and medium-term. These losses will be partitioned for leaching and erosion based on the experiments with tracers for N, K, Ca and Si. The fatal effects of fire on microbial communities and functions will be traced through abundance of symbiotic and saprotrophic fungal phyla and diazotrophic organisms, enzyme activities and PLFA composition in the topsoil. Microbial succession during after-fire-recovery will be studied with a special accent on stress-tolerant and mineral-weathering fungi. The functional role of fungi and bacteria will be supported by comparisons of qPCR analysis to high throughput sequencing data. Special focus will be given to fungi as under aerobic conditions on rock surfaces and at the root/soil interfaces, fungi are of particular importance: Stress-protected fungal cells (i) form extensive contacts with minerals and enhance chemical release of nutrients from minerals and (ii) accelerate the recolonization of soils after fire. Succession of microbial communities over short- and medium-term will be related to the increase of enzyme activities, PLFA composition, nutrient mobilization and accumulation in the topsoil. The aridity gradient from Pan de Azucar to Nahuelbuta will elucidate the effects of precipitation on absolute and relative losses of nutrients and ballast elements after fire as well as on ecosystem recovery. Results of the 1st phase will be used to generalize the nutrient cycling and input by weathering under steady state – in the stable ecosystems depending on climate. The results of the 2nd phase will allow generalization of the dramatic effects of the extreme event – fire – on the losses of the elements and their subsequent accumulation by weathering in recovering ecosystems during microbial and vegetation succession. Considering the worldwide increasing aridization and consequently the fire frequencies, the expected prediction of losses of nutrients and ballast elements from ecosystems and subsequent weathering possess a global relevance.