A gradsect or gradient-directed transect is a low-input, high-return sampling method where the aim is to maximise information about the distribution of biota in any area of study. Most living things are rarely distributed at random, their placement being largely determined by a hierarchy of environmental factors. For this reason, standard statistical designs based on purely random sampling or systematic (e.g. grid-based) systems tend to be less efficient in recovering information about the distribution of taxa than sample designs that are purposively directed instead along deterministic environmental gradients. Ecologists have long been aware of the significance of environmental gradient based approaches to better understand community dynamics and this is reflected especially in the work of Robert Whittaker (1967) and others. Although in practice, life-scientists intuitively sample gradients, until the early 1980s there was little formal theoretical or empirical support for such an approach, sample design being driven largely by traditional statistical methods based on probability theory incorporating random sampling. Origins Intensively sampled landscape-based surveys in Australia provided a reference platform for developing and testing a less logistically demanding and yet statistically acceptable gradient-based survey design that avoided the need for random or purely grid-based sampling. These initial studies and subsequently developed statistical support for purposive, gradient-based survey provided a formalized, practical alternative to more logistically demanding traditional designs. It was here the term gradsect was coined that coupled purposive, transect sampling with a hierarchical framework of environmental gradients considered to be key determinants of species distribution. Methodology In constructing a gradsect, existing information is initially reviewed in which a hierarchy of environmental gradients is first identified either by visual means (maps, aerial photographs etc..) or through numerical analysis or spatial analysis of institutional or other data sources. A typical regional gradsect for example may be constructed according to a primary climate gradient (temperature, moisture, seasonality) then a secondary gradient (geomorphology, lithology, major and minor drainage systems), a tertiary gradient possibly represented by a local soil catena or local land use farming system or finer scale gradient levels representing local vegetational sequences. Through an inspection of spatial overlays of all gradients, a minimum number of sample locations is then purposively located to reflect, as far as possible, total environmental variation. For logistic and other purposes (such as improving the capacity to locate rare species) the steepest gradients are usually selected. In this way an ideal gradsect is constructed that may then