Homogenisation of ECosystem functioning between Temperate and Neotropical streams due to AgRicultural land usE (HECTARE)

农业面积的扩大和集约化以及与之相关的森林砍伐、富营养化和生境异质性的改变仍然是影响世界范围内河流生态系统功能的最重要的压力源。关键环境特征的改变可能导致不同气候带河流特有的功能属性的丧失，并最终导致河流生态系统功能的分化。以往的研究大多局限于特定生物群系的单一功能，缺乏对气候区间河流生态系统的农业驱动功能同质化潜力的透彻理解。公顷项目分析了位于德国哈茨、巴西塞拉多和大西洋森林的原始和农业溪流的生态系统功能。通过食物网量化和生态系统生产力和呼吸测量的新组合，公顷提供了对温带和新热带河流的能量和物质通量的机制理解，包括它们与流域的营养耦合。在此基础上，将确定受农业土地利用影响的整个生态系统物质和能量通量的关键途径。与公顷一起提出的生物群落间方法将允许综合与农业土地利用相关的影响模式，并分析河流生态系统的功能同质化程度。

The expansion and intensification of agricultural areas and the associated deforestation, eutrophica-tion and modification of habitat heterogeneity remain the most important stressors to stream ecosys-tem functioning worldwide. The alteration of key environmental characteristics may cause the loss of functional attributes specific for streams in different climate zones and may ultimately lead to a ho-mogenisation of stream ecosystem functioning. Previous studies were mostly restricted to a single function in a particular biome and a thorough understanding on the potential for an agriculturally driven functional homogenisation of stream ecosystems among climate zones is lacking. The project HECTARE analyses ecosystem functioning of pristine and agricultural streams situated in the German Harz and in the Brazilian Cerrado and Atlantic forest. By the novel combination of quantification of food webs and measurements of ecosystem productivity and respiration, HECTARE delivers a mech-anistic understanding on energy- and matter fluxes in temperate and Neotropical streams including their trophic coupling to the catchments. Building on that, key pathways of whole-ecosystem matter and energy fluxes that are impacted by agricultural land use will be identified. The inter-biome ap-proach proposed with HECTARE will allow for a synthesis of impact patterns associated with agricul-tural land use and an analysis of the degree of functional homogenisation of stream ecosystems.