Integrated modelling of the response of aquatic ecosystems to land use and climate change in the Poyang lake region, China

流域特性、内流过程及其对水生生物的影响是密切相关的，但关键驱动力、过程和可能的反馈机制之间的相互作用尚未得到很好的了解。因此，我们项目的目的是开发一种综合模拟方法，以评估快速环境变化对水生生态系统的影响，并以长江(6260平方公里)的鄱阳湖区(中国)流域为例。联合测量和采样活动将是整合三种不同模型的基础：我们的目标是对动态DPSI(R)系统进行建模，首次将SWAT(集水过程)、HEC-RAS(在流过程)和MAXENT/BIOMOD(生物响应)模型结合起来。主要驱动因素(气候、土地利用、河道变化)是模型输入数据，而对生态系统的主要压力(水平衡、养分、沉积)是在SWAT和HEC-RAS的模型算法中定义和表示的。基于多重压力，我们的目标是动态评估模型输出中栖息地参数(如流量、深度、底物)状态的变化。最后，将通过分析MAXENT/BIOMOD模拟的分布范围的变化以及底栖无脊椎动物的生物多样性或生态系统健康指标的变化来评估状态对水生生态系统的影响，底栖无脊椎动物是淡水生态系统中的一个重要群体。考虑气候或土地利用变化的联合情景运行将特别增强对以下方面的理解：(1)景观过程和营养循环如何与生态水文和水生系统特性相互作用；(2)如何评估土地利用、气候和水形态变化对水生生态系统特性的影响。

Catchment properties, instream processes and their effects on aquatic organisms are closely linked, but the interaction of key driving forces, processes and possible feedback mechanism are yet not well understood. The aim of our project is thus the development of an integrated modelling methodology to assess the impact of fast environmental changes on aquatic ecosystems in the example catchment of the Changjiang (6260 km²) in the Poyang lake area (China). Joint measurement and sampling campaigns will be the basis for integrating three different models: we aim to model a dynamic DPSI(R)-system, for the first time coupling the models SWAT (catchment processes), HEC-RAS (in-stream processes) and MAXENT/BIOMOD (biological responses). Major drivers (climate, land use, channel alteration) are model input data, while the main pressures on the ecosystem (water balance, nutrients, sedimentation) are defined and represented in the model algorithms of SWAT and HEC-RAS. Based on the multiple pressures, we aim to dynamically assess the changes of the state of habitat parameters (e.g. flow, depth, substrate) in the model output. Finally, the impact of the state on the aquatic ecosystems will be evaluated by analysing shift of distribution ranges modelled by MAXENT/BIOMOD and changes in biodiversity or ecosystem health indicators of benthic invertebrates, an important group in freshwater ecosystems. Joint scenario runs considering climate or land use changes will particularly enhance understanding (1) how landscape processes and nutrient cycles interact with ecohydrological and aquatic system properties and (2) how the impact of land use, climate and hydromorphological change on aquatic ecosystem properties can be assessed.