Comparative assessment of satellite- and drone-based vegetation indices to predict arthropod biomass in shrub-steppes.

Arthropod biomass is a key element in ecosystem functionality and a basic food item for many species. It must be estimated through traditional costly field sampling, normally at just a few sampling points. Arthropod biomass and plant productivity should be narrowly related because a large majority of arthropods are herbivorous, and others depend on these. Quantifying plant productivity with satellite or aerial vehicle imagery is an easy and fast procedure already tested and implemented in agriculture and field ecology. However, the capability of satellite or aerial vehicle imagery for quantifying arthropod biomass and its relationship with plant productivity has been scarcely addressed. Here, we used unmanned aerial vehicle (UAV) and satellite Sentinel-2 (S2) imagery to establish a relationship between plant productivity and arthropod biomass estimated through ground-truth field sampling in shrub steppes. We UAV-sampled seven plots of 47.6-72.3 ha at a 4-cm pixel resolution, subsequently downscaling spatial resolution to 50 cm resolution. In parallel, we used S2 imagery from the same and other dates and locations at 10-m spatial resolution. We related several vegetation indices (VIs) with arthropod biomass (epigeous, coprophagous, and four functional consumer groups: predatory, detritivore, phytophagous, and diverse) estimated at 41-48 sampling stations for UAV flying plots and in 67-79 sampling stations for S2. VIs derived from UAV were consistently and positively related to all arthropod biomass groups. Three out of seven and six out of seven S2-derived VIs were positively related to epigeous and coprophagous arthropod biomass, respectively. The blue normalized difference VI (BNDVI) and enhanced normalized difference VI (ENDVI) showed consistent and positive relationships with arthropod biomass, regardless of the arthropod group or spatial resolution. Our results showed that UAV and S2-VI imagery data may be viable and cost-efficient alternatives for quantifying arthropod biomass at large scales in shrub steppes. The relationship between VI and arthropod biomass is probably habitat-dependent, so future research should address this relationship and include several habitats to validate VIs as proxies of arthropod biomass.

Reconciling livestock production and wild herbivore conservation: challenges and opportunities.

Increasing food security and preventing further loss of biodiversity are two of humanity's most pressing challenges. Yet, efforts to address these challenges often lead to situations of conflict between the interests of agricultural production and those of biodiversity conservation. Here, we focus on conflicts between livestock production and the conservation of wild herbivores, which have received little attention in the scientific literature. We identify four key socio-ecological challenges underlying such conflicts, which we illustrate using a range of case studies. We argue that addressing these challenges will require the implementation of co-management approaches that promote the participation of relevant stakeholders in processes of ecological monitoring, impact assessment, decision-making, and active knowledge sharing.

Avoiding over-implementation of agri-environmental schemes for steppe bird conservation: a species-focused proposal based on expert criteria.

This study presents an assessment, resulting from consultation with experts in steppe-bird conservation (scientists, officers and conservationists) using the Delphi method, of a broad range of agri-environmental measures (AEMs) which have been applied in agricultural areas in Spain, with particular reference to four threatened steppe bird species. The measures which experts have valued most highly relate to the maintenance of fallow land, the prohibition of agrochemicals and the suspension of certain agricultural practices when the species are nesting. Other AEMs which have frequently been mentioned as beneficial for steppe birds, including the maintenance of straw-mulched fallows and the abandonment of farmland, were rejected by the experts. The assessment showed a high degree of consensus between experts, although differences between the four studied species were detected. Delphi assessment indicated that different birds need different AEMs. In addition, expert evaluation showed that different AEMs can cause the same effect on the target species, which could generate an over-implementation of measures. Finally, we evaluated the financial implementation of the AEMs selected by the Delphi using a Special Protection Area for birds (SPA) in the Madrid region as a case study. All the hypothetical scenarios used yielded assumable costs, oscillating between 1 and 2 times the current AEMs expenditure. In conclusion, in extensive agrarian systems with already high conservation merits, the implementation of AEMS could be improved using species-specific assessments, thus avoiding over-implementation and improving the fit between costs and benefits for conservation.

SCaMC-1 promotes cancer cell survival by desensitizing mitochondrial permeability transition via ATP/ADP-mediated matrix Ca(2+) buffering.

Ca(2+)-mediated mitochondrial permeability transition (mPT) is the final common pathway of stress-induced cell death in many major pathologies, but its regulation in intact cells is poorly understood. Here we report that the mitochondrial carrier SCaMC-1/SLC25A24 mediates ATP-Mg(2-)/Pi(2-) and/or HADP(2-)/Pi(2-) uptake into the mitochondria after an increase in cytosolic [Ca(2+)]. ATP and ADP contribute to Ca(2+) buffering in the mitochondrial matrix, resulting in desensitization of the mPT. Comprehensive gene expression analysis showed that SCaMC-1 overexpression is a general feature of transformed and cancer cells. Knockdown of the transporter led to vast reduction of mitochondrial Ca(2+) buffering capacity and sensitized cells to mPT-mediated necrotic death triggered by oxidative stress and Ca(2+) overload. These findings revealed that SCaMC-1 exerts a negative feedback control between cellular Ca(2+) overload and mPT-dependent cell death, suggesting that the carrier might represent a novel target for cancer therapy.