Landscape sensitivity in time and space - an introduction

Landscape sensitivity may be discussed in terms of the response of landscap e systems to perturbation on different time and spatial scales. Unstable sy stems behave chaotically bur may show self organised criticality, while sta ble systems resist change until threshold values of system parameters ale e xceeded. Spatial sensitivity is expressed in different rates of change, bet ween landscape components or elements. This leads to divergence between lan dscape elements, and the inheritance of palaeoforms in present-day landscap e mosaics. Temporal sensitivity reflects the magnitude and frequency of ind ividual events nested within patterns of longer term environmental changes occurring on different timescales. The resulting landscape complexity refle cts the spatio-temporal sensitivity of earth surface systems over ten order s of scale magnitude. The connectivity within landscapes ensures that site instabilities can be propagated within multievent feedback systems. Landsca pes record their own histories in sediments and soils, but interpretation o f event stratigraphy may not be straightforward, while soil profiles can ab sorb individual events without erosion. Although we are increasingly able t o model the present, environmental management is dominantly about conservin g inherited properties of landscapes: forests, soils, floodplains, coastlin es. Landscape sensitivity for landscape management must, therefore, address not only active, largely nonlinear, environmental systems, but also the mo saics and palimpsests that are the inheritance from past environments. (C) 2001 Elsevier Science B.V. All rights reserved.