Evidence for 'critical slowing down' in seagrass:a stress gradient experiment at the southern limit of its range

The theory of critical slowing down, i.e. the increasing recovery times of complex systems close to tipping points, has been proposed as an early warning signal for collapse. Empirical evidence for the reality of such warning signals is still rare in ecology. We studied this on Zostera noltii intertidal seagrass meadows at their southern range limit, the Banc d'Arguin, Mauritania. We analyse the environmental covariates of recovery rates using structural equation modelling (SEM), based on an experiment in which we assessed whether recovery after disturbances (i.e. seagrass & infauna removal) depends on stress intensity (increasing with elevation) and disturbance patch size (1 m(2) vs. 9 m(2)). The SEM analyses revealed that higher biofilm density and sediment accretion best explained seagrass recovery rates. Experimental disturbances were followed by slow rates of recovery, regrowth occurring mainly in the coolest months of the year. Macrofauna recolonisation lagged behind seagrass recovery. Overall, the recovery rate was six times slower in the high intertidal zone than in the low zone. The large disturbances in the low zone recovered faster than the small ones in the high zone. This provides empirical evidence for critical slowing down with increasing desiccation stress in an intertidal seagrass system

Building connectomes using diffusion MRI: why, how and but

Why has diffusion MRI become a principal modality for mapping connectomes in vivo? How do different image acquisition parameters, fiber tracking algorithms and other methodological choices affect connectome estimation? What are the main factors that dictate the success and failure of connectome reconstruction? These are some of the key questions that we aim to address in this review. We provide an overview of the key methods that can be used to estimate the nodes and edges of macroscale connectomes, and we discuss open problems and inherent limitations. We argue that diffusion MRI-based connectome mapping methods are still in their infancy and caution against blind application of deep white matter tractography due to the challenges inherent to connectome reconstruction. We review a number of studies that provide evidence of useful microstructural and network properties that can be extracted in various independent and biologically-relevant contexts. Finally, we highlight some of the key deficiencies of current macroscale connectome mapping methodologies and motivate future developments

De Amazone: ontbossingen, biogeochemische cycli en klimaat

Abstract niet beschikbaarThe biogeochemical cycling of carbon, water, energy, aerosols, and trace gases in the Amazon Basin, and the interactions between deforestation, rainfall and climate were all investigated in this programme as a part of an integrated cluster of inter-linked and complemmentary research projects. These include LBA-EUSTACH (EUropean Studies on Trace gases and Atmospheric CHemistry as a contribution to the Large-scale Biosphere-Atmosphere experiment in Amazonia), LBA TRMM (Tropical Rainfall Measuring Mission), LBA WET AMC (LBA Wet Season Atmospheric Mesoscale Campaign) and LBA Project "The Effects of Tropical Deforestation on Climate" under the The Dutch National Research Programme on Global Air Pollution and Climate Change. All these projects were intregrated under the overall research objective of the LBA (Large Scale Biosphere Atmosphere Experiment in Amazon), and their set up enabled a full research synergy by for example the use of joint field research sites and other collaborative facilities. We present an overview of the design of these projects, the measurement sites and methods, and some preliminary research results.SG-NO

Biosfeer aspecten van de hydrologische cyclus. Synthese van internationaal onderzoek

Abstract niet beschikbaarBiospheric Aspects of the Hydrological Cycle (BAHC) was established as one of core projects of the International Geosphere Biosphere Programme (IGBP) in 1992. Its main focus is to study the role of the terrestrial biosphere in the hydrological cycle. BAHC is an interdisciplinary project combining and integrating expertise from several disciplines, including eco-physiology, biogeochemistry, hydrology and meteorology.The Global Energy and Water Experiment GEWEX was initiated in 1988 by the World Climate Research Programme (WCRP) to observe and model the hydrologic cycle and energy fluxes in the atmosphere, and at the land and ocean surface. GEWEX is an integrated program of research, observations, and science activities ultimately leading to the prediction of global and regional climate change. In this report, we present a brief overview of the synthesis research highlights of both international programmes with the primary focus on the biospheric feedbacks in the hydrological cycle and on interactions with the climate system. A full extended research synthesis book, to production of which this NOP project contributed, is currently in press by Springer Verlag (Kabat et al (eds), 2002: Vegetation, Water, Humans and the Climate: A New Perspective of an Interactive System, 650 pp; ISBN 3-540-42400-8)SG-NO

Integrale analyse van kwetsbaarheid voor klimaatveranderingen en aanpassingsmogelijkheden aan klimaatveranderingen in Nederland

Abstract niet beschikbaarIn recent decades, it has become increasingly clear that the global climate is becoming warmer and that regional climates are changing. This report summarizes the results of an integrated assessment of vulnerability to climate change and adaptation options in the Netherlands carried out between July 2000 and July 2001 within the framework of the Dutch National Research Program on Global Air Pollution and Climate Change (NRP-2). The project's main aims were: - to provide an overview of scientific insights, expert judgements and stakeholders' perceptions of current and future impacts (positive and negative) of climate change for several economic sectors, human health, and natural systems in the Netherlands, considering various cross-sectoral interactions, - to develop a set of adaptation options for these sectors through a participatory process with the main stakeholders, - to perform an integrated assessment of cross-sectoral interactions of climate change impacts and adaptation options. Climate change impacts and adaptation options have been investigated for several important economic sectors (including agriculture, forestry, fisheries, industry, energy, transport, insurance and recreation & tourism), human health and natural systems (including soils, water and biodiversity issues).The results of this study are based on literature survey, a dialogue with experts and stakeholders. We are convinced that the report represents the most essential and relevant aspects of the impacts and adaptation options for climate change in the Netherlands, given the scenario setting of this study, the state of the art of current scientific knowledge, and today's expert and stakeholders' perceptions of the issues at stake.SG-NO