A new German study recreated the local 100-year weather extremes of both drought and heavy rainfall. The researchers assessed the impacts of these extreme weather events on plots containing mixtures of grasses, herbs, shrubs and legumes, which represent naturally occurring grassland or heath communities.
For all plant communities, productivity remained broadly stable in the face of drought or heavy rainfall, despite the fact that the rate of plant tissue die-back (percentage of dead plant fibre above ground) significantly increased in response to both weather extremes. Interestingly, more diverse grassland communities (plots with more species) were less prone to die-back, a stress response, than plots that had fewer plant species.
The results show that if legumes were in the plots, overall plant productivity increased, regardless of the weather conditions. Also, in plots that contained a mixture of grasses and dwarf shrubs, productivity increased in response to heavy rainfall. This was attributed to the presence of a grass species that performs better under conditions of increased soil moisture. Other plant species performed better in drought conditions. Overall the contrasting results suggest that the complementary effects of different species in mixed plant communities should be considered in more detail.
ExtremExtreme weather also has an impact on soil and microbial processes, which in turn affects uptake of nutrients and water by plants. Future work should consider the influences of various climate change related weather extremes on these processes, to gain a more complete picture of the impact on plant productivity and ecosystem functioning.