Interactive plant-trait and climate effects on soil organic carbon along the Chilean coastal cordillera

有机碳进入土壤是风化和侵蚀的主要驱动力之一。反过来，这种输入主要受植被和气候的相互作用影响。了解气候和植被如何共同决定土壤有机碳，作为微生物的能量来源，作为风化引擎和侵蚀的稳定因素，是EarthShape计划（SPP 1803）的主要科学目标之一。在这个项目中，我们的目标是通过研究有机碳通量来实现这一目标，从植物生产力到凋落物分解和土壤中的碳动态，解开植物和气候的影响。基于我们的假设，气候和植物性状的相对重要性可能是规模依赖的，我们将在多个空间气候尺度上工作。这些规模包括三个生物群落沿着智利沿海科迪勒拉（干旱，地中海和湿温带）和两个对比的研究地点在这些生物群落。在这三个生物群落和六个研究地点的对比植物类型下的土壤有机碳特征的调查，将使我们能够部分解耦植被和气候的影响。此外，亦会研究植物及枯落物多样性对枯落物分解的影响。通过在为期两年的完全互惠实验中将植物凋落物和土壤在三个生物群落和地点之间转移，实现了进一步的脱钩。将从功能的角度来看待植被，碳输入，通过初级生产力，凋落物分解，土壤有机碳转化被描述为植物功能特性（化学，物理和物候）的功能。为了测试植被和气候对底土有机碳的影响，其特征是高持久性和长周转率，我们将把底土转移到温度、湿度和有机碳输入增加的表面。我们将应用创新的实验室设备（HPLC，ICM-PS，EA-IRMS，ANOOG）来描述沿着土壤剖面的叶，凋落物和土壤有机碳（颗粒和溶解）的化学成分（C，N，P，13 C，木质素，单宁，微量元素）。吸收-荧光同步测量技术包括激发发射矩阵荧光（EEM）技术和平行因子分析（PARAFAC）技术，将促进溶解性土壤有机碳化合物分析的发展。联合数据分析是该项目的一个重要组成部分，根据拟议的多尺度方法将植物，凋落物和土壤数据联系起来。我们的研究结果将包括一个基于气候和植被特征预测土壤有机碳含量的统计模型，包括生产力和最终土壤碳含量之间的主要步骤。这种改进的过程知识对于理解和模拟碳循环和与地貌有关的土壤过程非常重要。

The input of organic carbon into the soil is one of the major drivers of weathering and erosion. This input, in turn, is primarily controlled by interactive effects of vegetation and climate. Understanding how climate and vegetation together determine soil organic carbon, as an energy source for microorganisms as weathering engines and as a stabilizing factor in erosion, is one of the major scientific goals of the EarthShape program (SPP 1803). With this project we aim to pursue this goal by studying organic carbon fluxes, from plant productivity to litter decomposition and carbon dynamics in soils, disentangling plant and climate effects. Based on our hypothesis that the relative importance of climate and plant traits may be scale dependent we will work at multiple spatial-climatic scales. These scales encompass three biomes along the Chilean coastal cordillera (arid, mediterranean and wet-temperate) and two contrasting study sites within each of these biomes. The investigation of soil organic carbon characteristics below contrasting plant types within these three biomes and six study sites, will allow us to partially decouple vegetation and climate effects. The effect of plant and litter diversity on litter decomposition will also be studied. A further decoupling is achieved by translocating plant litter and soils between the three biomes and sites in a fully-reciprocal experiment over a period of two years. Vegetation will be regarded from a functional point of view, carbon inputs, via primary productivity, litter decomposition, and soil organic carbon transformations being described as functions of plant functional traits (chemical, physical and phenological). To test impacts of vegetation and climate on subsoil organic carbon characterized by a high persistence and a long turnover rate we will translocate subsoil up to the surface where temperature, moisture and organic carbon inputs increase. We will apply innovative lab devices (HPLC, ICM-PS, EA-IRMS, AQUALOG) to describe the chemical composition (C, N, P, 13C, lignin, tannin, trace elements) of leaf, litter and of soil organic carbon (particulate and dissolved) along the soil profile. Simultaneous absorbance-fluorescence measurement technique will advance the analyses of dissolved soil organic carbon compounds including Excitation Emission Matrix (EEM) Fluorescence and Parallel Factor Analysis (PARAFAC) techniques. The joint data analysis is an essential part of this project to connect the plant, litter and soil data following the proposed multi-scale approach. Our results will include a statistical model predicting soil organic carbon contents based on climate and vegetation traits, including the main steps between productivity and final soil carbon contents. This improved process knowledge is important for understanding and modelling carbon cycles and geomorphology-related soil processes.