| Summary: | Climate change is affecting the Arctic faster than anywhere else on the planet, with increases in temperature and precipitation predicted to have significant effects on Arctic ecosystems. Water availability is of key importance to plant growth in the Arctic, and the availability of grazing in the autumn is of particular importance to the winter survival of Arctic herbivores. Despite this, the effects of water availability on the senescence of plants in the Arctic is largely understudied. I experimentally tested how different levels of soil moisture impacted the senescence of a grass, an herb, and a shrub all commonly found on Svalbard, that are also important to the grazing of Svalbard reindeer. Increased soil moisture had a strong positive effect by delaying the timing of senescence of the grass in particular. Meanwhile, senescence was delayed for the herb and forb only under moderate increases in soil moisture, while high increases in soil moisture led to earlier senescence. Flooding events caused by heavy rainfall may have a strong negative impact on some species, such as the herb and forb, while species like the grass may be more resilient. These results indicate that a moderate increase in precipitation in the future may have a positive effect on the length of time with high quality forage available during the autumn, which may ameliorate the negative effects expected from increased icing events during the winter on Arctic herbivores such as the Svalbard reindeer.
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