Using fire to enhance rewilding when agricultural policies fail

Rewilding has been proposed as an opportunity for biodiversity conservation in abandoned landscapes. However, rewilding is challenged by the increasing fire risk associated with more flammable landscapes, and the loss of open-habitat specialist species. Contrastingly, supporting High Nature Value farmlands (HNVf) has been also highlighted as a valuable option, but the effective implementation of agricultural policies often fails leading to uncertain scenarios wherein the effects of wildfire management remain largely unexplored. Herein, we simulated fire-landscape dynamics to evaluate howfire suppression scenarios affect fire regime and biodiversity (102 species of vertebrates) under rewilding and HNVf policies in the future (2050), in a transnational biosphere reserve (Gerês-Xurés Mountains, Portugal-Spain). Rewilding and HNVf scenarios were modulated by three different levels of fire suppression effectiveness. Then, we quantified scenario effects on fire regime (burned and suppressed areas) and biodiversity (habitat suitability change for 2050). Simulations confirm HNVf as a longterm opportunity for fire suppression (up to 30,000 ha of additional suppressed areas between 2031 and 2050 in comparison to rewilding scenario) and for conservation (benefiting around 60% of species). Rewilding benefits some species (20%), including critically endangered, vulnerable and endemic taxa, while several species (33%) also profit from open habitats created by fire. Although HNVf remains the best scenario, rewilding reinforced by low fire suppression management may provide a nature-based solution when societal support through agricultural policies failsinfo:eu-repo/semantics/acceptedVersio

Incorporating fire-smartness into agricultural policies reduces suppression costs and ecosystem services damages from wildfires

In southern Europe, land abandonment and an unbalanced investment toward fire suppression instead of prevention has gradually increased wildfire risk, which calls for a paradigm change in fire management policies. Here we combined scenario analysis, fire landscape modelling, and economic tools to identify which land-use policies would reduce the expected wildfire-related losses in the Transboundary Biosphere Reserve ‘Gerês-Xurés’ (Spain-Portugal). To do so, we applied the least-cost-plus-net-value-change approach and estimated net changes in wildfire damages based on their implications for the 2010-2050 period and five ecosystem services: agriculture, pasture, timber, recreation and climate regulation. Four land-use scenarios were considered: (1) Business as Usual (BAU); (2) fire-smart, fostering more fire-resistant (less flammable) and/or fire-resilient landscapes (fire-smart); (3) High Nature Value farmlands (HNVf), wherein the abandonment of extensive agriculture is reversed; and (4) a combination of HNVf and fire-smart. HNVf is the best scenario for suppression cost savings, but it generates the lowest net present value of societal benefits from climate regulation. In fact, the most efficient scenario with the lowest societal discounted net suppression costs and change on ecosystem services damages is the HNVf + fire-smart scenario, as it also generates suppression cost savings from agricultural expansion, and lead to a significant reduction in damages on timber and recreational benefits. Therefore, reverting land abandonment through recultivation and promoting fire-resistant tree species is the most efficient way to reduce wildfire hazard. In this sense, payments for ecosystem services should reward farmers and landowners for their role in wildfire prevention. This study improves the understanding of the financial and societal benefits derived from reducing fire suppression spending and ecosystem services damage by undertaking fire-smart land-use strategies, which can be essential to enhance local stakeholders' support for Payments of Ecosystem Services policies for wildfire prevention

Bax Function in the Absence of Mitochondria in the Primitive Protozoan Giardia lamblia

Bax-induced permeabilization of the mitochondrial outer membrane and release of cytochrome c are key events in apoptosis. Although Bax can compromise mitochondria in primitive unicellular organisms that lack a classical apoptotic machinery, it is still unclear if Bax alone is sufficient for this, or whether additional mitochondrial components are required. The protozoan parasite Giardia lamblia is one of the earliest branching eukaryotes and harbors highly degenerated mitochondrial remnant organelles (mitosomes) that lack a genome. Here we tested whether human Bax expressed in Giardia can be used to ablate mitosomes. We demonstrate that these organelles are neither targeted, nor compromised, by Bax. However, specialized compartments of the regulated secretory pathway are completely ablated by Bax. As a consequence, maturing cyst wall proteins that are sorted into these organelles are released into the cytoplasm, causing a developmental arrest and cell death. Interestingly, this ectopic cargo release is dependent on the carboxy-terminal 22 amino acids of Bax, and can be prevented by the Bax-inhibiting peptide Ku70. A C-terminally truncated Bax variant still localizes to secretory organelles, but is unable to permeabilize these membranes, uncoupling membrane targeting and cargo release. Even though mitosomes are too diverged to be recognized by Bax, off-target membrane permeabilization appears to be conserved and leads to cell death completely independently of mitochondria

What do you mean, ‘megafire’?

BACKGROUND : ‘Megafire’ is an emerging concept commonly used to describe fires that are extreme in terms of size, behaviour, and/or impacts, but the term’s meaning remains ambiguous. APPROACH : We sought to resolve ambiguity surrounding the meaning of ‘megafire’ by conducting a structured review of the use and definition of the term in several languages in the peer-reviewed scientific literature. We collated definitions and descriptions of megafire and identified criteria frequently invoked to define megafire. We recorded the size and location of megafires and mapped them to reveal global variation in the size of fires described as megafires. RESULTS : We identified 109 studies that define the term ‘megafire’ or identify a megafire, with the term first appearing in the peer-reviewed literature in 2005. Seventy-one (~65%) of these studies attempted to describe or define the term. There was considerable variability in the criteria used to define megafire, although definitions of megafire based on fire size were most common. Megafire size thresholds varied geographically from > 100–100,000 ha, with fires > 10,000 ha the most common size threshold (41%, 18/44 studies). Definitions of megafire were most common from studies led by authors from North America (52%, 37/71). We recorded 137 instances from 84 studies where fires were reported as megafires, the vast majority (94%, 129/137) of which exceed 10,000 ha in size. Megafires occurred in a range of biomes, but were most frequently described in forested biomes (112/137, 82%), and usually described single ignition fires (59% 81/137). CONCLUSION : As Earth’s climate and ecosystems change, it is important that scientists can communicate trends in the occurrence of larger and more extreme fires with clarity. To overcome ambiguity, we suggest a definition of megafire as fires > 10,000 ha arising from single or multiple related ignition events. We introduce two additional terms – gigafire (> 100,000 ha) and terafire (> 1,000,000 ha) – for fires of an even larger scale than megafires.DATA AVAILABILITY STATEMENT: A list of the references from which the data were extracted can be found in the Appendix A: Data sources. The data used in this study are openly available at zenodo.org: https://doi.org/10.5281/zenodo.6252145.Threatened Species Recovery Hub; NSW Bushfire Risk Management Research Hub; Australian Wildlife Society; World Wildlife Fund.http://wileyonlinelibrary.com/journal/gebZoology and Entomolog

CWP release from ESVs is Bax specific.

<p>A) ESVs in encysting Bax-expressing cells treated with the membrane-permeable Bax-inhibiting peptide Ku70 are at least partially protected. Note the co-localization of Bax (green) with (partially intact) ESVs and significantly less cytoplasmic or nucleoplasmic CWP signal than in untreated cells (compare with <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0000488#pone-0000488-g002" target="_blank">FIG. 2C</a>).16-May B) Deletion of the Bax C-terminus uncouples Bax targeting to ESV membranes and CWP release. BaxΔ22 lacks the C-terminal 22 amino acids of Bax and localizes to membranes of intact ESV. C, D) Electron micrographs of representative cells expressing Bax or BaxΔ22 at four hours post induction. C) Encysting trophozoite from the population expressing BaxΔ22 showing numerous ESVs with electron dense material (arrowheads). ESV and general compartment morphology are indistinguishable from wild type cells (not shown). Enlarged region shows an individual ESV. Peripheral vesicles underlying the plasma membrane are clearly visible. D) ESVs or organelle remnants are not present in surviving cell expressing Bax. Nuclei, and parts of the microtubule structures of the anterior flagella and significantly enlarged PVs are visible. N, nuclei. Scale bars: 2 µm.</p

Expression of human Bax in induced <i>Giardia</i> trophozoites does not affect mitosomes.

<p>A) Confocal microscopy analysis of the subcellular distribution of Bax in transgenic cells. Recombinant Bax (left panel, green) does not localize to mitosomes (middle panel, red) labeled with an anti-IscS rabbit antiserum as a mitosome marker. The signature central mitosome structure is indicated with an arrowhead. The merged images show a clear lack of co-localization. Nuclear DNA is stained with DAPI (blue). Inset: differential interference contrast (DIC) image. Scale bar: 5 µm. B) The central mitosome structure (Cm, arrowhead) is resolved as a tightly packed array of spherical organelles in electron microscopy of adherent cells. The subunits are indistinguishable from individual peripheral mitosomes (Pm, arrow). This organelle structure is unchanged in transgenic trophozoites expressing Bax. N, nucleus; Bb, basal bodies; Ax, axonemes; Vd, ventral disk.</p

Expression of Bax is lethal for <i>Giardia.</i>

<p>A) Induced cells expressing Bax stop dividing and die in the course of 6 hours. Inset: semi-quantitative RT-PCR analysis of Bax mRNA levels in transgenic cells pre induction (PI) and 4 hours after induction. B) Subcellular localization of CWPs in ESVs of encysting wild type cells labeled by a monoclonal anti-CWP antibody at 4 h post induction. C) Bax abolishes ESV formation in encysting cells and causes accumulation of CWPs in the cytoplasm and the nucleoplasm. Inset: differential interference contrast (DIC) image. Scale bar: 5 µm.</p

Data files from Regos et al. (2018)

These data files include the environmental suitability predicted from the SESAM framework for each bird species, under each run simulation and management scenario. It also includes the Natura 2000 network at 100 m and all remaining files required to run MARXAN simulations

Biodiversity scenarios neglect future land-use changes

International audienceEfficient management of biodiversity requires a forward-looking approach based on scenarios that explore biodiversity changes under future environmental conditions. A number of ecological models have been proposed over the last decades to develop these biodiversity scenarios. Novel modelling approaches with strong theoretical foundation now offer the possibility to integrate key ecological and evolutionary processes that shape species distribution and community structure. Although biodiversity is affected by multiple threats, most studies addressing the effects of future environmental changes on biodiversity focus on a single threat only. We examined the studies published during the last 25years that developed scenarios to predict future biodiversity changes based on climate, land-use and land-cover change projections. We found that biodiversity scenarios mostly focus on the future impacts of climate change and largely neglect changes in land use and land cover. The emphasis on climate change impacts has increased over time and has now reached a maximum. Yet, the direct destruction and degradation of habitats through land-use and land-cover changes are among the most significant and immediate threats to biodiversity. We argue that the current state of integration between ecological and land system sciences is leading to biased estimation of actual risks and therefore constrains the implementation of forward-looking policy responses to biodiversity decline. We suggest research directions at the crossroads between ecological and environmental sciences to face the challenge of developing interoperable and plausible projections of future environmental changes and to anticipate the full range of their potential impacts on biodiversity. An intergovernmental platform is needed to stimulate such collaborative research efforts and to emphasize the societal and political relevance of taking up this challenge

Global scenarios for biodiversity need to better integrate climate and land use change

International audienc