According to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC 2013), the chance of heavy rains and flooding is increasing globally, as precipitations will be “concentrated into more intense events, with longer periods of little precipitation in between”. We also observed that altered precipitation patterns can modify earthworm burrowing behaviour, as earthworms had produced more burrows under the intense regime.Ĭlimate change does not only entail shifts in long-term trends, but also variations in the frequency and magnitude of intense weather events (IPCC 2013). Underlying mechanisms, such as macropore formation and enhanced nutrient cycling, are discussed. We found that anecic earthworms can offset negative effects of intense rainfall on plant growth aboveground. The number of such macropores was 2.4 times higher under the intense precipitation regime, despite similar earthworm survival.
Continuous vertical macropores were found only in the mesocosms to which earthworms had been added. Waterlogging duration aboveground was not affected, whereas soil moisture contents after intense rainfall tended to drop faster with earthworms present. Intense rains reduced ryegrass shoot biomass (by 16–21 % on average) only in the absence of earthworms. Short-term response of soil moisture and lagged response of plant growth were measured, and soil macroporosity was quantified. In a field experiment, intact soil mesocosms with ryegrass ( Lolium multiflorum), with or without introduced adult Lumbricus terrestris, underwent either a precipitation regime with two intense rain events (36 mm, at beginning and end of spring), or a control regime with the same cumulative rainfall but no intense events. Since anecic earthworms make vertical burrows that improve water infiltration, we hypothesised that they can counteract such disturbance. By causing waterlogging, they may increase soil erosion and soil surface compaction, hamper seedling establishment, and reduce plant growth. Intense rains are becoming more frequent.
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