Suchergebnisse

In drylands, soil surfaces in interplant spaces are usually covered by biocrusts, which consist of communities of heterotrophic and chemoautotrophic bacteria, cyanobacteria, mosses, lichens, microalgae, fungi and other organisms. Cyanobacteria are of special interest because of their capacity to promote biocrust succession or increase soil fertility and stability. Therefore, some studies have analyzed their communities in different ecosystems, focusing on how different factors, such as temperature or altitude, influence their composition. Nevertheless, to our knowledge, the relationship between ecosystem degradation and cyanobacterial community composition has not yet been studied in depth. This could be determinant for the successful development of tools for restoring degraded biocrusts by cyanobacterial inoculation. Thus, the objective of this study was to analyze the effect of the ecosystem degradation level on cyanobacteria composition from topsoil communities, where they are keystone pioneering organisms. To do this, we analyzed the cyanobacterial diversity by molecular sequencing (16S rRNA gene) of the DNA extracted from biocrusts at different developmental stages, which were collected from three ecosystems in southeastern Spain. The selected ecosystems represent different "land-condition" states as a result of degradation processes. In one of them soil was removed by mining (the Gador quarry), the second is a natural badland area (El Cautivo) where water erosion is intense, and the third ecosystem is a well-preserved area (Balsa Blanca). Our findings show that cyanobacterial richness decreases (up to 28 OTUs) as degradation increases and biocrust developmental stage decreases. Also, the relative abundances of most of the species were significantly correlated with the degradation state of the sampling site, either showing a positive or negative trend. Two of the species which increased in abundance with site degradation, and were especially abundant in incipient biocrusts, were Leptolyngbya frigida and Trichocoleus desertorum, while other species, also showing an increase in abundance with degradation, but having a higher relative abundance in most developed biocrusts, were Nostoc commune, Tolypothrix distorta and Scytonema sp. The significant correlation of these species with degradation at different biocrusts developmental stages, suggests an alternative developmental sequence for drylands, at least in more degraded ecosystems. In less degraded ones, the composition of the major cyanobacterial groups followed the common pattern of bundle-forming cyanobacteria (54.7%) pertaining to the Microcoleus genus followed by other non-heterocystous filamentous (17.4%), unicellular/colonial (7.5%) and heterocystous cyanobacteria (1.1%). In comparison, the cyanobacterial groups dominating the most incipient biocrusts, colonizing the most degraded soil, were the filamentous non-heterocystous (50.7%) and the bundleforming cyanobacteria (48.9%). Therefore, our results show that some cyanobacterial species, which do not belong to traditional pioneer genera, are frequent colonizers of degraded soils, and then, they could be potentially used for producing a more efficient inoculum for inducing biocrust formation and restoring degraded soils. Finally, it is also remarkable that L. frigida appears as dominant in some biocrusts from drylands (up to 74.9% of abundance) being therefore demonstrated its wide distribution in nonpolar biomes and its capacity to also inhabit degraded arid soils ; This work was supported by the projects RESUCI (CGL 2014-59946-R), the project REBIOARID (RTI 2018-101921-B-I00), and the GL 2013-44870-R and GL 2017-6258-R projects, all of them founded by the Spanish National Plan for Research and the European Union ERDF funds

This article argues that geographers must study the power of words as integral parts of human–environment relationships, with particular attention to local meanings, to intervene more effectively in the Anthropocene. Words are important tools by which people come to understand environmental changes and develop plans to facilitate mitigation and adaptation or, alternatively, to postpone these responses. This project considers the portion of Texas underlain by the Ogallala aquifer as a system of communication, exploring stakeholder articulations through in-depth interviews. The semiotic concepts of gradients, grading, degradation, and grace are employed to facilitate consideration of how verbal articulations intersect with resource use, conservation, anthropogenic environmental change, and action within a highly conservative political context. ; Office of the VP for Research

Localized flux, production and/or degradation coupled to limited diffusion are well-known to result in stable spatial concentration gradients of biomolecules in the cell. In this study, we demonstrate that this also holds true for small ions, since we found that the close membrane apposition between the membrane of a phagosome and the surface of the cargo particle it encloses, suffices for stable gradients of protons and iron cations within the lumen of the phagosome. Our data show that in phagosomes containing hexapod-shaped silica colloid particles, the phagosomal membrane is ruptured at the positions of the tips of the rods, but not at other positions. This results in the confined leakage at these positions of protons and iron from the lumen of the phagosome into the cytosol. In contrast, acidification and iron accumulation still occur at the positions of the phagosomes of the cores of the particles. Our study strengthens the concept that the coupling of metabolic and signaling reaction cascades can be spatially confined by localized limited diffusion. ; ST, SS and GB are funded by a Young Investigator Grant from the Human Frontier Science Program (HFSP; RGY0080/2018). GB has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program (grant agreement No. 862137) and the Netherlands Organization for Scientific Research (Vidi grant NWO-ALW VIDI 864.14.001). ST further acknowledges support from the Department of Atomic Energy, Government of India, under project no. 12-R&D-TFR-5.04-0800 and 12-D&D-TFR-5.10-1100, the Simons Foundation (Grant No. 287975) and the Max Planck Society through a Max-Planck Partner-Group.

The empirical and scientifically documents prove that misuse of natural resource causes
degradation in it. So natural resources conservation is important in approaching sustainable
development aims. In current study, Landsat Thematic Mapper images and grazing gradient
method have been used to map the extent and degree of rangeland degradation. In during
ground-based data measuring, factors such as vegetation cover, litter, plant diversity, bare soil,
and stone & gravels were estimated as biophysical indicators of degradation. The next stage,
after geometric correction and doing some necessary pre-processing practices on the study
area's images; the best and suitable vegetation index has been selected to map rangeland
degradation among the Normalized Difference Vegetation Index (NDVI), Soil Adjusted
Vegetation Index (SAVI), and Perpendicular Vegetation Index (PVI). Then using suitable
vegetation index and distance parameter was produced the rangelands degradation map. The
results of ground-based data analysis reveal that there is a significant relation between
increasing distance from critical points and plant diversity and also percentage of litter. Also
there is significant relation between vegetation cover percent and distance from village, i.e.
the vegetation cover percent increases by increasing distance from villages, while it wasn't the
same around the stock watering points. The result of analysis about bare soil and distance
from critical point was the same to vegetation cover changes manner. Also there wasn't
significant relation between stones & gravels index and distance from critical points. The
results of image processing show that, NDVI appears to be sensitive to vegetation changes
along the grazing gradient and it can be suitable vegetation index to map rangeland
degradation. The degradation map shows that there is high degradation around the critical
points. These areas need urgent attention for soil conservation. Generally, it shows that the
most parts of rangelands in studying area have been degraded. So conservation priorities on
degraded rangelands have been recognized based on current degradation.

Colonial nesting and roosting birds can degrade their habitat by soil salinization, eutrophication, and acidification associated with excessive deposition of avian excreta. We studied the impact of a protected wading bird colony on soil microbial communities from cork oak woodlands in Doñana National Park (SW Spain). Over one year we analyzed soil properties (pH, salinity, soluble N and P forms, extractable organic carbon - EOC -), microbial activity (basal respiration, community-level physiological profile, extracellular enzyme activities) and community structure (fungal, bacterial and archaeal terminal restriction fragments -TRFs-) along a gradient of bird nesting intensity. Bird nesting largely impacted soil chemical environment, with increases from 25 to 500 μS cm−1 in soil salinity, from 6 to 725 mg kg−1 in soil P, from 5 to 22 mg kg−1 in N-NH4, and from 5.4 to 245 mg kg−1 in N-NO3 between the extremes of the nesting intensity gradient in the wet season. Most of these chemical changes were enhanced in the dry season. We observed positive linear or log-linear relationships between the bird nesting footprint on soils (indicated by an integrated soil chemistry index) and microbial biomass, basal respiration and most of the studied enzyme activities. This was likely due to the concurrent increases in EOC along the avian intensity gradient, which counteracted the negative impacts of salinity. Soil P and EOC were the main drivers for fungal, bacterial and archaeal TRFs diversity. Bacterial TRFs richness and diversity index decreased along the avian intensity gradient in the dry season, while archaeal TRFs diversity increased in those soils highly salinized by excess of avian excreta deposition. Our study clearly shows that this oversized bird colony has profound effects on soil chemistry and biological activity, and highlights the need for a re-evaluation of management strategies in this protected area, towards a greater consideration of soil processes in conservation priorities. ; We are grateful to the Consejería de Medio Ambiente (Andalusian Government) and to the Organismo Autónomo Parques Nacionales for financial support, through the DECALDO (091/2009) and the BIOGEOBIRD (P09-RMN-4987) projects, and to the Doñana National Park and Doñana Biological Reserve managers for the use of their facilities and the support to carry out the field work. Rubén Rodríguez and Héctor Garrido from the Doñana Monitoring Team provide us with data of cork oak occupation by the colony. We also thank Adela Moreno fir her work with T-RFLP analysis. MTD was supported by a Juan de la Cierva Postdoctoral fellowship and JMA by a FPU-MEC grant from the Spanish Ministry of Economy and Competitiveness. ; Peer reviewed

Assessing forest changes is the baseline requirement for successful forest management. Measurement, Reporting, and Verification (MRV) are three essential components for achieving such assessments. Community participation in resource monitoring and management is increasingly seen as a scientifically efficient, cost-effective, and equitable way to employ such practices, particularly in the context of REDD+. We developed a multidisciplinary approach to study the feasibility of Participatory MRV (PMRV) across three sites along a forest degradation gradient in Indonesia. We looked at both the local and national level needs of MRV. Our approach combines: (1) social research focusing on the enabling conditions for local participation in MRV; (2) governance analyses of existing MRV systems in forestry and health; and (3) remote sensing work comparing overlaps and gaps between satellite imagery and local assessments of forest changes. We considered in our approach the possible multiple benefits of PMRV (carbon mitigation, biodiversity conservation, livelihood security). Our study helped to identify the multiple stakeholders (communities, NGOs and governments) and what the levels of governance should be to make PMRV design and implementation feasible and sustainable.

The study assessed the causal factors of land degradation in urban areas of Abeokuta and the employed control measures by residents of the communities. A qualitative approach, which encompasses observational techniques – participant/field observation, interactive discussion and photographic capturing, was used for collection of data on land degradation in the study area. Analysis of collected data showed land gradients, rainfall and run-offs, erosion, entrenched foot paths, sand scraping/mining, poor/absence of drainage system and land covers as causal factors of land degradation in the study area. The study though observed that control measures such as filling of drenches with sand bags, wood logs, bricks and stones were employed by residents in the study area, construction of good drainage system was presumed to be the most appropriate and sustainable control measure of water erosion in the study area.