Nitrate leaching under climate change

Climate change may alter the services ecosystems provide by changing ecosystem functioning. As ecosystems can also resist environmental perturbations, it is crucial to consider the different processes that influence resilience.  “Climate proofing” can identify potential climate-related threats to ongoing delivery of ecosystem services. Dr. Katri Rankinen and colleagues have published a new study modelling the potential for increased nitrate(NO3) concentrations in drinking water due to climate change. They analyzed catchment-scale changes in ecosystem services connected to water purification in southern Finland by combining climate change scenarios with process-based forest growth (PREBAS) and eco-hydrological (PERSiST and INCA) models. By using the aforementioned model chain, they improved traditional model calibration by including timing of forest phenology and duration of the snow-covered period from networks of cameras and satellite data. They upscaled the combined modelling results with scenarios of population growth to produce vulnerability maps. Their results show that boreal ecosystems seemed to be strongly buffered against increased NO3 leaching by a combination of increases in evapotranspiration and vegetation NO3 uptake. Societal vulnerability varied greatly between scenarios and municipalities. The most vulnerable areas were agricultural regions on permeable soil types.

INCA-N INCA-P New Papers

Tradeoffs for agri-environmental measure effectiveness

Katri Rankinen and colleagues have published a study of the effectiveness of agri-environmental measures to reduce nitrogen (N) and phosphorus (P) loads to receiving waters in Finland.

In areas with intensive agriculture, excessive nutrient loading causes deterioration of receiving surface waters. A number of measures are used to reduce nutrient loads but there can be tradeoffs. While nitrate and particulate phosphorus load can be efficiently controlled by reducing tillage frequency and increasing vegetation cover, this often leads to increased loading of bioavailable phosphorus. In the latest phase of the EU Rural Programme, measures with the highest potential to reduce the nutrient loading to receiving waters were setting limits for fertilization of arable crops and retaining plant cover on fields with, e.g., no-till methods and uncultivated areas. Due to the latter two measures, the area of vegetation cover Finland has increased since 1995, suggesting clear effects on nutrient loading in the catchment scale as well.

In the new paper, Katri Rankinen and colleagues modeled the effectiveness of agri-environmental measures to reduce N and P loads to receiving waters. They showed that INCA-P was able to simulate both fast (immediate) and slow (non-immediate) processes that influence P loading from catchments. It was also evident that no-till methods had increased bioavailable P load to receiving waters, even though total P and total N loading were reduced.