The rise and fall of turlough typologies: A call for a continuum concept

Turloughs are seasonal ground-water-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 We used unpublished and published data on a per-turlough basis to explore the main variables affecting turlough ecology in Ireland.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 hydrologic 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 conservation.