Abstract
BackgroundSpace-for-time substitution—that is, the assumption that spatial variations of a system can explain and predict the effect of temporal variations—is widely used in ecology. However, it is questionable whether it can validly be used to explain changes in biodiversity over time in response to land-cover changes.HypothesisHere, we hypothesize that different temporal vs spatial trajectories of landscape composition and configuration may limit space-for-time substitution in landscape ecology. Land-cover conversion changes not just the surface areas given over to particular types of land cover, but also affects isolation, patch size and heterogeneity. This means that a small change in land cover over time may have only minor repercussions on landscape composition but potentially major consequences for landscape configuration.MethodsUsing land-cover maps of the Paris region for 1982 and 2003, we made a holistic description of the landscape disentangling landscape composition from configuration. After controlling for spatial variations, we analyzed and compared the amplitudes of changes in landscape composition and configuration over time.ResultsFor comparable spatial variations, landscape configuration varied more than twice as much as composition over time. Temporal changes in composition and configuration were not always spatially matched.SignificanceThe fact that landscape composition and configuration do not vary equally in space and time calls into question the use of space-for-time substitution in landscape ecology studies. The instability of landscapes over time appears to be attributable to configurational changes in the main. This may go some way to explaining why the landscape variables that account for changes over time in biodiversity are not the same ones that account for the spatial distribution of biodiversity.
Highlights
One of the main goals of landscape ecology is to provide a better understanding of how populations and communities respond to changes in land use and cover [LUC] in space and time [1]
Ecological conservation requires both an understanding of the ecological processes associated with landscape composition and configuration, and a complete understanding of the landscape dynamics of composition and configuration induced by LUC changes which strongly impact biodiversity
The influence of landscape composition and configuration on biodiversity has been widely investigated in the literature based on two strong assumptions: the habitat/matrix paradigm [5,6] and the space-fortime substitution [7] applied to landscape ecology studies to predict future biodiversity dynamics [8]
Summary
Space-for-time substitution—that is, the assumption that spatial variations of a system can explain and predict the effect of temporal variations—is widely used in ecology It is questionable whether it can validly be used to explain changes in biodiversity over time in response to land-cover changes. Landcover conversion changes not just the surface areas given over to particular types of land cover, and affects isolation, patch size and heterogeneity. This means that a small change in land cover over time may have only minor repercussions on landscape composition but potentially major consequences for landscape configuration
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