Action: Remove tree canopy to reduce pond shading
- One before-and-after study in Denmark found that translocated garlic toads established breeding populations following pond restoration that included canopy removal.
- One before-and-after study in the USA found that canopy removal did not increase hatching success of spotted salamanders.
Shading of ponds by tree canopies reduces water temperature, affects plant communities and can result in chemical changes resulting from the decomposition of increased leaf litter. Such changes can affect amphibian populations. For example, warm ponds are more favourable for amphibian growth and development.
Studies in which tree canopies were removed as one of a combination of interventions for the restoration of ponds are discussed in ‘Restore ponds’.
Supporting evidence from individual studies
A before-and-after study in 1994–1997 of two restored ponds in Jutland, Denmark (Jensen 1997) found that translocated garlic toads Pelobates fuscus established breeding populations of in both ponds. Breeding was recorded in one in 1996 and the other in 1997. Ponds were restored by removing surrounding willows and by levelling the banks of one pond. Forty-three toads were captured from a pond being eliminated by development. Four egg strings were laid and raised in captivity. The 43 adults and 1,000 tadpoles were released into one of the restored ponds in 1994. Toads were monitored by tadpole and call surveys.
A before-and-after study in 2005–2007 of a restored forest pond in Illinois, USA (Sacerdote & King 2009) found that hatching success of spotted salamanders Ambystoma maculatum did not increase following canopy removal. Two egg masses failed in 2005 and 2006 before canopy removal and two failed in 2007 after removal. Restoration started in 2000 and included destruction of drainage tiles, clearing of invasive plants and prescribed burning. Canopy thinning was undertaken in winter 2006–2007. An egg mass was placed in two mesh enclosures (56 x 36 x 36 cm) in the pond. Eggs were monitored every five days until hatching was complete.
- Jensen B.H. (1997) Relocation of a garlic toad (Pelobates fuscus) population. Memoranda Societatis pro Fauna et Flora Fennica, 73, 111-113
- Sacerdote A.B. & King R.B. (2009) Dissolved oxygen requirements for hatching success of two Ambystomatid salamanders in restored ephemeral ponds. Wetlands, 29, 1202-1213