The rise and fall of turlough typologies

Visser Marjolein, Eugenie Regan, James Moran, Mike Gormally, Micheline Sheehy Skeffington, 2006. The rise and fall of turlough typologies: a call for a continuum concept. Wetlands, in press - to be published in the September edition of Wetlands 26(3). related work

Abstract: Turloughs are seasonal groundwater-dependent wetlands that occur in the karst
landscape of western Ireland. Various typologies based on between-site variation have
been applied to turloughs. However valid in understanding turlough functioning, these
typologies are difficult to relate to one another, tend to overlook within-site variation, and
do not address management issues affecting these priority habitats of the European
Union. Furthermore, typologies have not fully utilized available data and lack the
comprehensive perspective needed to capture processes driving turlough ecology. We use
unpublished and published data on a per-turlough basis to explore the main variables
affecting turlough ecology in Ireland. Multivariate analysis shows that turloughs do not
split into distinct types; rather there is one continuum from dry to wet sites, which affects
all aspects of turlough ecology. This dry-wet continuum arises from various degrees of
karstification of the underlying and surrounding bedrock, which in turn leads to different
water inputs, water chemistries and different deposits on the turlough floor. Few
turloughs can be considered as truly dry or wet; most are intermediate or dry-wet
mosaics. Turloughs or parts of turloughs at extremes of the dry-wet continuum need
different protection measures to prevent water pollution, manage summer grazing or
maintain the hydrological regime. Although turlough typologies seem logical and
straightforward in theory, in practice typing turloughs is difficult. Trying to fit turloughs
within typologies that are weakly supported by the data on which they are based can lead
to problems if inappropriately used. A dry-wet continuum concept not only better fits
these same data but also gives scope for a more flexible approach to turlough