October 2025 Science Summary

Greetings,

I've got a mixed bag of four mostly unrelated science articles this month.

If you know someone who wants to sign up to receive these summaries, they can do so at http://subscribe.sciencejon.com (no need to email me).

CLIMATE CHANGE:
Chen et al. 2025 reviews the evidence (from 21 studies with at least 10 years of data) that climate change may cause 3 problems (see Fig 1): mountaintop species going extinct when conditions become too warm for them, species not able to move upslope as fast as conditions change, and bottomland diversity declining b/c no warm-tolerant species can replace areas abandoned by species moving upslope. Using a model they found that mountaintop extinctions are not happening more than expected w/o climate change, many species ARE moving upslope but rarely having range contract, and only limited homogenization of bottomland species. They note including moisture changes and nitrogen deposition could have changed the results, and more research is needed to figure out why these problems are occurring in limited cases.


FOREST CARBON:
Schnabel et al 2025 has experimental evidence that after 16 years, planted forests in Panama with a mix of 5 native species sequestered 57% more aboveground carbon than monocultures. Both treatments lost soil carbon relative to the pasture they started with (see section 4.3 for possible explanations) but still gained a net of 24.7 t C / ha (90.7 t CO2e/ha) due to the aboveground gains. See  https://news.mongabay.com/2025/04/diverse-forests-and-forest-rewilding-offer-resilience-against-climate-change/ for more.


DATA AND DEFORESTATION:
Roquette et al. 2025 is ostensibly about the technical details around land use mapping in Mato Grosso, Brazil. But it actually makes a much broader point: boring things like data sources and algorithms used can have an outsize backdoor policy impact. They argue that a shift in how land use was classified could sneakily allow a ton of deforestation. Basically by changing how "forest" is defined and reclassifying some forest as a type of savanna (confusingly, cerrado is an ecosystem but the Cerrado is a biome / region), this could allow deforestation since 80% of forest has to be set aside from development but only 35% of savanna does. In some cases the new map actually does the reverse (classifying what was savanna as forest) but that can be reversed upon request. The worst case scenario is that up to 4,1 million ha could be authorized for deforestation.


MINING AND TOXICITY:
Foerster et al. 2025 found that giant otters in the Pantanal are showing evidence of mercury contamination in the Pantanal – higher when they’re closer to gold mines (except for streams close to the mine over land but not connected by water). Their results aren’t conclusive but it seems likely that the values are high enough to be causing toxicity, and that otters aren’t able to flush out the mercury by molting their fur, nor by having selenium bind to the mercury. They measured mercury in fur rather than directly in the liver, but based on other research they think it’s likely levels are high enough in some animals to cause serious toxicity and perhaps even death. 


REFERENCES:
Chen, Y.-H., Lenoir, J., & Chen, I.-C. (2025). Limited evidence for range shift–driven extinction in mountain biota. Science, 388(6748), 741–747. https://doi.org/10.1126/science.adq9512

Foerster, N., Soresini, G., Leuchtenberger, C., Bócoli, D. de A., Paiva, J. de B., Brait, C. H. H., & Mourão, G. (2025). Pervasive mercury contamination of a semi-aquatic apex predator across the Pantanal wetland. Environmental Conservation, 1–6. https://doi.org/10.1017/S0376892925100155

Roquette, J. G., Vacchiano, M. C., Daher, F. R. G., & Finger, Z. (2025). Pseudo-legal deforestation due to changes in the classification of native vegetation in Mato Grosso, Brazil. Environmental Conservation, 1–7. https://doi.org/10.1017/S037689292510012X

Schnabel, F., Guillemot, J., Barry, K. E., Brunn, M., Cesarz, S., Eisenhauer, N., Gebauer, T., Guerrero‐Ramirez, N. R., Handa, I. T., Madsen, C., Mancilla, Lady, Monteza, J., Moore, T., Oelmann, Y., Scherer‐Lorenzen, M., Schwendenmann, L., Wagner, A., Wirth, C., & Potvin, C. (2025). Tree Diversity Increases Carbon Stocks and Fluxes Above—But Not Belowground in a Tropical Forest Experiment. Global Change Biology, 31(2). https://doi.org/10.1111/gcb.70089


Sincerely,
 
Jon
 
p.s. These four foster puppies were getting some wiggles out in my yard before a "puppy party" which raises money for an animal rescue (Homeward Trails) and helps them find homes

October 2023 science summary

Greetings,

This month I have just two articles - one on conservation priorities (a longer than usual review) and one on how mining affects tropical rivers. I also forgot to post on this site for a few weeks, sorry!

If you know someone who wants to sign up to receive these summaries, they can do so at http://bit.ly/sciencejon (no need to email me).

CONSERVATION PRIORITIES:
Mair et al. 2021 proposes the use of a "species threat abatement and restoration (STAR)" metric with two scores. The threat abatement one for a location (START) sums up each threatened species present, with higher threat like Critically Endangered scoring higher, favoring locations with more species that are more threatened. The idea is to estimate effort to abate all threats (which seems unreasonable). The restoration score (STARR) divides 'restorable habitat' for all threatened species in a given pixel by global habitat for that species, and sums across species.

The paper calculates both for threatened terrestrial vertebrates. START results look pretty similar to range-size rarity scores for threatened species or a few other existing metrics, and suffer from the same issues (bias to data-rich places, lack of accurate info in many places). STARR seems more conceptually interesting but I'm pretty suspicious that the projected range maps are valid (given issues w/ current range maps) and since they didn't screen out any low-feasibility areas (like highly productive ag) it doesn't seem too useful. I also struggle to understand how they could have come up with the map in Fig 2b using the methods they describe. But that could be me being slow rather than a problem with the analysis.

FRESHWATER:
Dethier et al 2023 (briefly summarized in Walmsley 2023) finds that mining in tropical countries is dramatically increasing sediment in rivers. 80% of the 173 rivers affected by mining that they studied had sediment concentrations more than double what they were prior to mining. This is a pretty coarse estimate using satellite data, so the actual sediment estimates are very rough, but the general pattern should be valid.


REFERENCES:
Dethier, E. N., Silman, M., Leiva, J. D., Alqahtani, S., Fernandez, L. E., Pauca, P., Çamalan, S., Tomhave, P., Magilligan, F. J., Renshaw, C. E., & Lutz, D. A. (2023). A global rise in alluvial mining increases sediment load in tropical rivers. Nature, 620(7975), 787–793. https://doi.org/10.1038/s41586-023-06309-9

Mair, L., Bennun, L. A., Brooks, T. M., Butchart, S. H. M., Bolam, F. C., Burgess, N. D., Ekstrom, J. M. M., Milner-Gulland, E. J., Hoffmann, M., Ma, K., Macfarlane, N. B. W., Raimondo, D. C., Rodrigues, A. S. L., Shen, X., Strassburg, B. B. N., Beatty, C. R., Gómez-Creutzberg, C., Iribarrem, A., Irmadhiany, M., … McGowan, P. J. K. (2021). A metric for spatially explicit contributions to science-based species targets. Nature Ecology & Evolution, 5(6), 836–844. https://doi.org/10.1038/s41559-021-01432-0

Walmsley, B. (2023). Satellite images show the widespread impact of mining on tropical rivers. Nature, 620(7975), 729–730. https://doi.org/10.1038/d41586-023-02349-3

Sincerely,
 
Jon
 
p.s. This is a photo of a giant anteater that I saw on a recent trip to the Pantanal in Brazil. If you're curious I have more Pantanal photos and Pantanal videos.