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

集水区特性、河流过程及其对水生生物的影响密切相关，但关键驱动力、过程和可能的反馈机制之间的相互作用尚不清楚。因此，我们项目的目的是开发一种综合建模方法，以鄱阳湖地区长江流域（6260平方公里）为例，评估快速环境变化对水生生态系统的影响。联合测量和采样活动将是整合三种不同模型的基础：我们的目标是建立一个动态DPSI(R)系统的模型，首次将SWAT（流域过程）、HEC-RAS（流内过程）和MAXENT/BIOMOD（生物响应）模型耦合起来。主要驱动因素（气候、土地利用、河道改造）是模型输入数据，而生态系统的主要压力（水平衡、养分、沉积）则在SWAT和HEC-RAS的模型算法中定义和表示。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、基质）状态的变化。最后，通过分析MAXENT/BIOMOD模型的分布范围变化，以及淡水生态系统中重要的底栖无脊椎动物的生物多样性和生态系统健康指标的变化，评估这种状态对水生生态系统的影响。考虑气候或土地利用变化的联合情景运行将特别增进对以下方面的理解：(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、气候和水文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.