Ditches biodiversity on Ouse Washes LPA farmland Jonathan Graham

Location of the Ouse Washes

LPA and location of 175 sample drains (8 IDB areas)

175 drains sampled in June/July 2013 and 2014 Plants (within drain and on banks) by Jonathan Graham. Water beetles by Martin Hammond. Other species of interest.

Field drain (1-3m wide)

IDB drains (3-7m wide)

Large drains (7-60m wide)

Findings Plants (118 bank and 120 drain species) – 1 Endangered, 5 Vulnerable and 2 Near Threatened (in England) and 3 Nationally Scarce. Water beetles (120 species) – 1 Vulnerable, 4 Near Threatened and 18 Nationally Scarce. Other noteworthy fauna including common amphibians (Common Frog, Common Toad, Smooth Newt), Odonata and BAP species including Water Vole and Spined Loach.

Plants (11% of samples) (single sample) Whorled Water-milfoil Fringed Heartwort (single sample)

Water beetles Berosus luridus Agabus undulatus (17% of samples)

Other noteworthy species Spined Loach (2 sample points)

Drains of conservation importance 85 samples (48%) qualify as drains of conservation importance 43 (24%) qualify for plant species alone 30 (17%) qualify for both plant and water beetles 12 (7%) qualify for water beetles alone.

Relationship between environmental factors (drain width, water depth, pH, turbidity, conductivity, management, adjacent land use) and drains of conservation importance conservation value correlates closely with drain width (3 -7m wide), early successional stage, open water and good light penetration; these factors appear linked to IDB management (regular weed clearance, mild scraping of the bed and maintenance of high summer water levels for irrigation) grazed pasture important for water beetles alone big drains important for a few specialised species (riffle beetles and larger pondweeds)

Summary Ouse Washes LPA: has a high proportion drains of conservation importance (48% of samples). provides important habitat for several species of aquatic plants and beetles which have their British stronghold in the East Anglian Fens. includes many drains of conservation importance that are managed IDB drains within intensively managed arable farmland.