A multi-scale approach for analyzing landscape service dynamics

Shifting societal needs drive and shape landscapes and the provision of their services. This paper presents a modelling approach to visualize the regional spatial and temporal dynamics in landscape service supply as a function of changing landscapes and societal demand. This changing demand can result from different policy targets. In this paper we conceptualise the system in which these dynamics take place by explicitly addressing (i) the multifunctional character of a landscape, (ii) the different spatial levels at which interactions between landscape service supply, demand, and land management occur, and (iii) trade-offs in service supply as a result of land management actions. Next, we translate the resulting conceptual framework into an operational model. As a demonstration, this model is applied to simulate changes in landscape service supply driven by regional policies in a rural region of the Netherlands. This application demonstrates potential trade-offs, which emerge in a spatially explicit way in the region over time. It illustrates the potential relevance of modelling landscape service dynamics for environmental management and decision makin

Desertification in the Sahel: Towards better accounting for ecosystem dynamics in the interpretation of remote sensing images

To date, the interpretation of remote sensing images has not revealed wide-spread degradation of the vegetation in the Sahel. However, the interpretation of spectral information depends on a range of assumptions regarding the dynamics of the Sahelian vegetation as a function of rainfall variability and human management. Recent papers have presented diverging views on the vegetation dynamics of the Sahel and how these can be analysed with remote sensing images. We present a further analysis of the vegetation dynamics of semi-arid rangelands, in particular the Sahel, and the subsequent implications for the interpretation of remote sensing images. Specifically, the ecological processes driving the response of the Sahelian vegetation to rainfall variation are re-examined, and a regression analysis of NPP versus rainfall data is carried out. It is shown that the relation between the interannual variation in NPP and rainfall in the Sahel is non-linear and that this relation differs between sites with different average annual rainfall. It has been common practise in remote sensing studies for the Sahel to aggregate data from various Sahelian sites in order to obtain an average relation between rainfall, NPP and Rain Use Efficiency, and to assume these relations to be linear. This paper shows that this approach may lead to a bias in the interpretation of remote sensing images and that further work is required to clarify if wide-spread ecosystem degradation has occurred in the Sahel

Concept and valuation of landscape functions at different scales

Natural, semi-natural and cultivated ecosystems and landscapes provide many goods and services to human society that are of great ecological, socio-cultural and economic value (Millennium Ecosystem Assessment 2005). In environmental planning and decision-making, however, these benefits are often not fully taken into account and productive, multifunctional landscapes continue to be converted into more simple, often single-function land use types (e.g. croplands) or turned into wastelands (e.g. eroded land after clear-cut logging or polluted and over-fished shelf-seas). Yet, increasingly studies are showing that the total value of multifunctional use of natural and semi-natural landscapes is often economically more beneficial than the value of the converted systems (Balmford et al. 2002). The question therefore is how to identify and quantify the many benefits of multi-functional landscapes in order to take more balanced decisions regarding trade-offs involved in land use planning in view of the increasing demands for space and resources

The challenge of mapping the human connectome based on diffusion tractography

Tractography based on non-invasive diffusion imaging is central to the study of human brain connectivity. To date, the approach has not been systematically validated in ground truth studies. Based on a simulated human brain data set with ground truth tracts, we organized an open international tractography challenge, which resulted in 96 distinct submissions from 20 research groups. Here, we report the encouraging finding that most state-of-the-art algorithms produce tractograms containing 90% of the ground truth bundles (to at least some extent). However, the same tractograms contain many more invalid than valid bundles, and half of these invalid bundles occur systematically across research groups. Taken together, our results demonstrate and confirm fundamental ambiguities inherent in tract reconstruction based on orientation information alone, which need to be considered when interpreting tractography and connectivity results. Our approach provides a novel framework for estimating reliability of tractography and encourages innovation to address its current limitations

Author Correction: The challenge of mapping the human connectome based on diffusion tractography.

An amendment to this paper has been published and can be accessed via a link at the top of the paper