Synthetic soil crusts against green-desert transitions : a spatial model

Altres ajuts: Botin Foundation (Banco Santander through its Santander Universities Global Division) i CERCA Programme/Generalitat de CatalunyaSemiarid ecosystems are threatened by global warming due to longer dehydration times and increasing soil degradation. Mounting evidence indicates that, given the current trends, drylands are likely to expand and possibly experience catastrophic shifts from vegetated to desert states. Here, we explore a recent suggestion based on the concept of ecosystem terraformation, where a synthetic organism is used to counterbalance some of the nonlinear effects causing the presence of such tipping points. Using an explicit spatial model incorporating facilitation and considering a simplification of states found in semiarid ecosystems including vegetation, fertile and desert soil, we investigate how engineered microorganisms can shape the fate of these ecosystems. Specifically, two different, but complementary, terraformation strategies are proposed: Cooperation -based: C -terraformation; and Dispersion -based: D -terraformation. The first strategy involves the use of soil synthetic microorganisms to introduce cooperative loops (facilitation) with the vegetation. The second one involves the introduction of engineered microorganisms improving their dispersal capacity, thus facilitating the transition from desert to fertile soil. We show that small modifications enhancing cooperative loops can effectively modify the aridity level of the critical transition found at increasing soil degradation rates, also identifying a stronger protection against soil degradation by using the D -terraformation strategy. The same results are found in a mean-field model providing insights into the transitions and dynamics tied to these terraformation strategies. The potential consequences and extensions of these models are discussed

Projections of global and UK bioenergy potential from Miscanthus x giganteus – feedstock yield, carbon cycling and electricity generation in the 21st century

Funding Information Natural Environment Research Council. Grant Numbers:NE/M019691/1, NE/P019951/1 Engineering and Physical Sciences Research CouncilPeer reviewedPublisher PD

World Atlas of Desertification - Introductory Brochure

The brochure introduces the concept of the World Atlas of Desertification which relies on converging evidence of combined human-environment processes pointing out that land degradation cannot be modeled satisfactorily at global scales.The introductory brochure provides a short overview of the main land degradation issues, through illustration of a number key global datasets and some case study examples that reflect the global patterns and pathways to solutions. The brochure start with highlighting the human dominance that drives global environmental changes. The consequences of feeding a growing population include agriculture expansion and intensification, illustrated by maps and data on irrigation and nutrient use. Aridity and drought are important phenomena aggravating the already present human pressures on the environment. Other pressure patterns playing at global scale are illustrated with examples from China, India, S. America and the Sahel, along with a forward view on solutions.JRC.H.5-Land Resources Managemen

Remotely sensed albedo allows the identification of two ecosystem states along aridity gradients in Africa

Empirical verification of multiple states in drylands is scarce, impeding the design of indicators to anticipate the onset of desertification. Remote sensing‐derived indicators of ecosystem states are gaining new ground due to the possibilities they bring to be applied inexpensively over large areas. Remotely sensed albedo has been often used to monitor drylands due to its close relationship with ecosystem status and climate. Here, we used a space‐for‐time‐substitution approach to evaluate whether albedo (averaged from 2000 to 2016) can identify multiple ecosystem states in African drylands spanning from the Saharan desert to tropical Africa. By using latent class analysis, we found that albedo showed two states (low and high; the cut‐off level was 0.22 at the shortwave band). Potential analysis revealed that albedo exhibited an abrupt and discontinuous increase with increased aridity (1 − [precipitation/potential evapotranspiration]). The two albedo states co‐occurred along aridity values ranging from 0.72 to 0.78, during which vegetation cover exhibited a rapid, continuous decrease from ~90% to ~50%. At aridity values of 0.75, the low albedo state started to exhibit less attraction than the high albedo state. Low albedo areas beyond this aridity value were considered as vulnerable regions where abrupt shifts in albedo may occur if aridity increases, as forecasted by current climate change models. Our findings indicate that remotely sensed albedo can identify two ecosystem states in African drylands. They support the suitability of albedo indices to inform us about discontinuous responses to aridity experienced by drylands, which can be linked to the onset of land degradation.This work was supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant XDA19030500), the National Key Research and Development Program of China (Grant 2016YFC0503302), the European Research Council (BIODESERT project, ERC Grant Agreement 647038), the Joint PhD, Training Program of the University of Chinese Academy of Sciences, and the Research Foundation of Henan University of Technology (Grant 31401178)

Structure and agency: understanding water policy changes in West Africa

Ownership of development processes has been high on the international agenda since the Paris Declaration of 2005. There is, however, much discussion about whether highly aid-dependent governments can really ‘own’ policy reforms in their countries. In this paper, we argue that the ownership of policy reforms is the outcome of an interaction between individual agency and structural conditions. Taking the implementation of Integrated Water Resources Management (IWRM) in Burkina Faso (since 1996) and Mali (since 2004) as an entry point, the paper describes the interplay between national policy makers, international organizations and dominant development discourses in the shaping of water policy reforms in both countries over the past 15 years. Despite the apparent uniformity of the global IWRM paradigm, a qualitative comparison of water policy changes in the two countries shows that policy reforms, as well as the extent to which they are ‘owned’ by national policy makers, are significantly distinct. This can be explained by different forms of individual agency and diverse structural conditions at a national level

Modeling sand wave characteristics on the Belgian Continental Shelf and in the Calais-Dover Strait

The capability of the model of Besio et al. (2006) to predict the main geometrical characteristics (crest orientation, wavelength,…) of tidal sand waves is tested by comparing the theoretical predictions with field data. In particular the field observations carried out by Mouchet (1990) and Van Lancker et al. (2005) along the continental shelf of Belgium are used. Additional comparisons are carried out against the field measurements described by Le Bot (2001) and Le Bot and Trenteseaux (2004) which were carried out in an adjacent region. Attention is focused on the prediction of the wavelength of the bottom forms. Indeed, the capability of a linear stability analysis to predict the occurrence of sand waves has been already tested by Hulscher and van den Brink (2001) and more recently by van der Veen et al. (2006). The obtained results show that the theoretical predictions fairly agree with field observations even though some of the comparisons suggest that the accuracy of the predictions depends on the accurate evaluation of the local current and sediment characteristics

Sodium Butyrate Enhancement of Protein Expression

We studied in chimeric EGFP-Photinus luciferase HeLa cells the expression of fluorescence and luminescence in different cell culture conditions (medium with or without Serum, static or dynamic conditions, in suspension or on microcarriers) as a model to follow the productivity of a recombinant protein. By studying the effect of Butyrate known as general but unpredictable stimulating agent for protein expression, we were able to establish the optimal conditions for efficacy ( concentration, time of addition, ...