Flood, drought and the inter-annual variation to the number and size of ponds and small wetlands in an English lowland landscape over three years of weather extremes

Ponds are biodiversity hotspots, but pond conservation is hampered by problems auditing these small, often temporary, habitats. Data on temporal changes to the number of ponds in response to weather variations are lacking. Annual and seasonal changes to the numbers and area of wetted ponds in a lowland farm in England were surveyed by field walks between November 2010 and November 2013. Plant communities were recorded to identify variations in pond type between land-uses. The study period coincided with severe drought up until April 2012 followed by record breaking precipitation. The wetted areas of ponds in wetlands and dune slacks showed the strongest relationship with rainfall over the preceding 4-6 months, whilst the areas of ponds in arable or pasture fields varied more with rainfall in the previous month. Ponds from different land-uses supported different plant communities and all types added to the overall total site biodiversity. Plant communities of ponds in arable fields benefitted from the extreme wet summer of 2012. The results show that the number and area of ponds varied significantly between years and seasons and that different pond types in different land-uses may vary in their response to extreme weather.