from these ditches through the soil into the field. On soils with lower rates of
water transmission, movement of water into the field from surrounding ditches
becomes insufficient to replace water lost from the field by evapotranspiration in
late spring and summer. On undamaged peat, a water table of 20–30 cm below
the soil surface is recommended for breeding Snipe (RSPB, EN and ITE 1997).
Again, variation in surface topography is helpful in maintaining high water
levels, especially if shallow ditches help to irrigate areas around them.
14.6 Managing dwarf shrub habitats
Dwarf shrub habitats consist of heathland, moorland, maquis, garrigue, and
other vegetation comprised of dense, predominantly evergreen low shrubs.
Some dwarf-shrub habitats are prevented from succeeding to tall scrub and
woodland by edaphic and/or climatic factors, but most are prevented by periodic
burning, cutting, and/or grazing. Most experience of managing dwarf-shrub
communities to benefit birds stems from management of heather dominated
(ericaceous) upland moorlands and lowland heathlands in the United Kingdom.
A large proportion of upland moorlands in the United Kingdom have been
traditionally managed to encourage high densities of Red Grouse Lagopus
344 |Habitat management
Fig. 14.5Flooding grassland can increase the accessibility of soil invertebrates
to breeding waders such as lapwings by suppressing vegetation growth. If pools remain
into late spring and summer, they are rapidly colonized by aquatic invertebrates and
provide important feeding areas for wader chicks. (Malcolm Ausden and RSPB Images)