In addition to producing oxygen, plants also need oxygen in the soil in the purview of their roots’ respiration. The more the soil is saturated with water, the more the oxygen supply to the plant roots will be hampered. Plants need additional oxygen if the soil warms. As a result, severe rainfall may cause oxygen stress, which will worsen as heat increases.
In addition to oxygen stress, rural areas may also be affected by waterlogging, caused by the surface water inundation. This is not reflected on this map.
When does oxygen stress occur?
Oxygen stress can mainly be expected during severe rainfall in very warm time periods. In summer, plant rootage expands significantly. Sudden inundation will suffocate the plant and may even cause it to die off completely.
Vegetation in the natural environment adapts to periods of oxygen stress, e.g., through species featuring aerial roots, such as reeds and marsh marigolds. Their spongy tissue enables them to transport oxygen from the atmosphere to their roots. Another adaptation is very shallow rooting (sundew, butterwort). As mosses do not have roots, many moss species, e.g., various peat mosses, thrive on soaking wet soil.
What does the map show?
The map shows the annual maximum oxygen deficit for a continuous field of grass during a consecutive 10-day period. To provide a univocal picture of the differences in risk of oxygen stress for the whole of the Netherlands, these maps are consistently based on grass fields. In actual practice, many surfaces will be bare or covered by vegetation that is either more or less vulnerable than grass.
This oxygen deficit will directly result in a loss of crop yield. The magnifying glass will tell you that under the WH scenario, oxygen stress will increase considerably by 2050, especially in peat areas and brook valleys.
The current climate map is quite similar to maps combining drought damage and wet damage, as per a report by Hack-Ten Broeke et al. (2008) (see Figures 5.2 and 5.3 in this report). On this basis, the “no to little”, “moderate”, and “much” classes referred to in the table could correspond to <15%, 15%-40%, and >40% yield losses, respectively. The impact on potatoes, onions, and flower bulbs can be expected to be higher.
Concerning the natural environment, oxygen stress can be translated into the proportion of wet species (hygrophytes) in the vegetation. This connection is reflected in the figure below.
What sources were used?
Oxygen stress (gram of O2 per square meter per 10 days) has been calculated using the PROBE model (Witte et al., 2015) based on a national soil map, KNMI weather data, and groundwater levels calculated in a 250-m spatial resolution using the National Hydrological Instruments (De Lange et al. (2014); www.nhi.nu). The stress standard has been developed by Bartholomeus et al. (2011) based on a model (Bartholomeus et al., 2008) that simulates oxygen transport in the soil and oxygen consumption by plant roots.
How can this information be used?
The map provides an indicative, regional-level picture of the occurrence of oxygen stress; the changes in the WH scenario provide a particularly good impression of the regions that can expect the highest impact in terms of agriculture and nature. In the Climate Impact Atlas, the drought stress map can be combined with grassland, farmland, and nature reserves.
The map provides an indicative, regional-level picture of the occurrence of oxygen stress; the changes in the WH scenario provide a particularly good impression of the regions that can expect the highest impact in terms of agriculture and nature. In the Climate Impact Atlas, the drought stress map can be combined with grassland, farmland, and nature reserves.
Provinces, municipalities, district water boards, farmers, and nature management bodies require a higher spatial resolution to conduct studies and take decisions. For many regional studies, a 25-m resolution appears to be the standard nowadays. The Agricultural Water Guide is the most efficient instrument to calculate agricultural effects. This guide is a method that distinguishes multiple crops. It takes account of multiple aspects associated with wet damage, such as problems with nutrient intake and so-called consequential loss. To calculate the impact on the natural environment, the Nature Water Guide can be used. This comprises the PROBE model. This Water Guide also takes account of such factors related to oxygen stress as nutrient content and acidity of the soil, and the increase in both drought stress and oxygen stress under the WH scenario.
