Global distribution of forest landscapes covered by airborne LiDAR
Only a pre-print for now, but after 4 years of hard work I couldn't resist sharing this!
The Global Canopy Atlas: analysis-ready maps of 3D structure for the world's woody ecosystems
📜: doi.org/10.1101/2025...
Huge team effort led by the brilliant Fabian Fischer!
This cartoon panel shows a tropical forest with tapir, monkey, thrush, and tortoise. The text reads: In tropical forests, animals play an important role in reforestation - often by eating seeds and then dispersing them through their, uh... poop!
This panel shows cartoon drawings of a Sumatran rhino, bare-throated bellbird, Mariana flying fox, and mountain gorilla. The text reads: But as wildlife populations decline due to habitat loss, invasive species and poaching, seed dispersal also slows.
The panel has a sparse forested landscape with just the thrush remaining. The text reads: "A new study found that, due to animal losses, the potential for carbon storage from natural forest regrowth has been cut in half.
The last panel shows a tapir dispersing seeds. The text reads: Reforestation can be one of the most effective natural climate solutions. To unlock its full potential, we must restore and protect nature's seed dispersers. The credit text says: Mikhalia Markham / The Nature Conservancy.
Very cool to see our recent study turned into a cartoon (what!?)
Anyone else want to skip the middleman and just publish cartoons from here on out?
🔗 www.pnas.org/doi/abs/10.1...
Really excited to share our new paper on #causalinference & #climatechange attribution out in #EcologyLetters today!
Are you asking "how much" or "if" climate change has impacted your system, then this paper is for you!
🧪🌏🌐🍁🌺🌱🌿
onlinelibrary.wiley.com/doi/10.1111/...
Are you an early-career biologist or ecologist who would benefit from an invited seminar? Would you like to come to UMaine next fall or spring to give a talk? Leave a brief comment with some info about what you do. I'm co-hosting our seminar series again, and am filling out our rosters.
Screenshot of the MIT homepage with a story about our recent PNAS article. The text reads: A new study shows fruit-eating animals help tropical forests absorb carbon, by dispersing seeds and enabling new trees to grow. “When we lose our animals, we’re losing the ecological infrastructure that keeps our tropical forests healthy and resilient,” Evan Fricke says.
MIT homepage today:
40% hornbill
40% figs
20% me yelling about seed dispersers
Press release here: mit.edu
In our new perspective in PNAS we call for a move away from conservation focused on saving individual species to focusing on ecological processes, which underpin ecosystem resilience and the capacity to adapt to environmental change. Led by @josephtobias.bsky.social 🌍🌐🧪
www.pnas.org/doi/10.1073/...
Thanks for spreading the word! Check out a thread about our work here👇
Thank you for reading and sharing!
Deep thanks to the stellar coauthors Susan Cook-Patton, Charlie Harvey, and César Terrer. And to photographer Christian Ziegler for these excellent seed disperser images.
A young bonobo (Pan paniscus) eats a Mammea africana fruit in a Congolese forest, dispersing the large seeds of this tropical tree. The ecological role of this endangered seed disperser is threatened by habitat loss, fragmentation, and illegal hunting within their restricted range. Image credit: Christian Ziegler.
The take-home message is clear.
Overlooking nature’s tree planters risks missing ‘win-win’ pathways for both climate mitigation and biodiversity conservation.
Figure showing the mapping of aboveground carbon accumulation potential in light of seed dispersal disruption. (A) The current (c. 2020) regrowth potential of tropical forest and savanna ecosystems while accounting for seed dispersal disruption. Hatching indicates savanna biomes. Estimates of model uncertainty are presented in Fig. S7. (B) The cumulative effect of land use change over the period 2000-2020 on natural regrowth potential. (C) the impact of seed dispersal disruption on regrowth potential in tropical forest areas. Values estimate the degree to which current levels of seed dispersal disruption would limit carbon accumulation for regrowing forests at each location. Inset panel shows the distribution of lost carbon accumulation potential across sites identified as potential restoration areas by ref. (36) that occur in the tropical forest biomes. Model uncertainty is presented in Fig. S8.
These numbers help show where natural regrowth can be effective, in which areas a human hand is needed to meet climate mitigation potential, or how we can leverage seed dispersers’ roles to amplify forest restoration.
Figure showing effect of seed dispersal disruption on aboveground carbon accumulation. (A) Stand age versus fitted values of aboveground carbon during natural regrowth, with color gradient showing levels of seed dispersal disruption at each site. (B) Standardized effect sizes representing the effect of a 1 SD increase in the predictor variable on carbon accumulation rates annualized over the first 30 years of regrowth. Bars show 95% and 99% CIs, points show median posterior values, and filled points indicate 95% CIs that do not overlap zero. (C) Annualized carbon accumulation rate under either natural regrowth or monoculture plantation without other reported interventions such as fertilization and irrigation, with lines showing model estimates for average environmental conditions and shaded areas showing 95% credible intervals.
Despite seed disperser decline, natural regrowth still matches or exceeds the carbon gains of tree planting by people in many areas.
And natural regrowth often has much lower implementation costs and better biodiversity outcomes.
A great hornbill (Buceros bicornis) eats a fig in Royal Manas National Park, Bhutan. Hornbills are key long-distance seed dispersers in Asian tropical forests, but forest degradation, hunting, and wildlife trade threaten the ecological roles they play. Image credit: Christian Ziegler.
Two key findings:
-Aboveground carbon accumulates 4x faster in regrowing tropical forests where seed dispersal by animals is most intact vs. most disrupted.
-Current seed dispersal disruption levels cut carbon uptake of proposed reforestation sites by 57% on average.
Figure showing the modeling seed dispersal disruption. (A) Example of the processes modeled to estimate seed dispersal function, showing observed seed retention times versus model-predicted values based on species traits by ref. (28) (see also Fig. S2). (B) Observed relationship between the human footprint index and displacement distances over a typical seed retention period, based on field observations of animal movement; detailed results are presented in Figure S3. (C-H), examples of seed dispersal disruption values and distribution of values across regional scales; dashed lines show estimates c. 2000 and filled area shows estimates c. 2020. Inset plots show areas in the Amazon Basin (C), the Congo Basin (E), and Borneo (G).
We combined results of thousands of local field studies on seed-dispersing animals and human impacts to map a ‘seed dispersal disruption’ index across the tropics.
We then paired it with carbon accumulation data from thousands of tropical regrowth plots, along with other environmental variables.
Motivation: Tropical regrowth forests are currently the largest contributor to the land carbon sink, which absorbs a third of global emissions annually.
But over 80% of tropical trees rely on animals to regenerate, and seed dispersers are declining. What does that mean for tropical forest regrowth?
Our new study shows how animal biodiversity loss is a climate problem: tropical forests recover far less carbon where seed dispersers have declined.
We’re not just losing forests – we’re losing their ability to regrow.
Reversing that trend could align biodiversity recovery with climate solutions.🧵
Using a multiproxy dietary analysis of the extinct South American proboscidean Notiomastodon platensis, the authors confirm that it consumed fruits and may have acted as a seed disperser www.nature.com/articles/s41...
The deadline for the 2026 CV4Ecology workshop has been extended until June 21! Spread the word! Tell your friends! Get those applications over the finish line!
cv4ecology.caltech.edu/call_for_app...
Thoughtful coverage in The Guardian of our new global reforestation maps, published yesterday in Nature Communications.
www.theguardian.com/environment/...
Glad to have contributed to this effort led by Kurt Fesenmyer at TNC.
www.nature.com/articles/s41...
An illustration of mammal species that would naturally occur near La Brea, California, with color used to show species that still exist there like coyotes and mule deer, and greyscale used to show extinct species like ground sloths and saber-toothed cats. Illustration credit: Oscar Sanisidro.
For #BiodiversityDay, check out some of the mammals that “should” be in Southern California today (species that went extinct since the last interglacial are greyed out).
From our paper www.science.org/doi/10.1126/... Illustrated by coauthor @ohsanisidro.bsky.social
Photo of seed dispersal by Vireo gracilirostris, an important seed disperser on the oceanic island of Fernando de Noronha in Brazil where this species is endemic.
We’d love your help spreading this (the message, not the seeds - though both matter!)
Big thanks to the stellar coauthors: Carolina Bello, Becky Chaplin-Kramer (@beckyck.bsky.social), Daisy Dent, Ken Feeley (@kjfeeley.bsky.social), Mauro Galetti, Juanpe González-Varo, Ruben Heleno, Leighton Reid.
There’s still much to learn:
• Which plants and ecosystems are most vulnerable to disperser loss?
• How do disperser declines interact with other change drivers?
• What are (and how can we measure) the costs to human well-being?
• What strategies best restore seed dispersal and its benefits?
Example results from a study modeling seed dispersal function. The figure has two panels with scatter plots with points representing ecoregion globally. The y axis in each is change in long-distance seed dispersal function and the x axis is change in animal species richness and functional diversity, respectively. These results show that losses of bird and mammal species or functional diversity correspond to far greater proportional losses of seed dispersal function. https://www.science.org/doi/epdf/10.1126/science.abk3510
But we’re making progress.
New data syntheses and models are capturing functional changes across large scales, helping reveal long-term impacts, which range from reduced forest product provisioning and weakened carbon storage to impaired wildfire recovery and degraded habitats for animals.
Screenshot of a Google Trends query showing search interest from 2004 to today, comparing the search terms “seed disperser” and “pollinator”. The pollinator line is increasing over time while the seed disperser line is stuck at zero interest.
Why are seed dispersers missing from the conversation?
One idea: Experiments can demonstrate societally relevant impacts of pollinator decline within a growing season. For seed disperser decline, they unfold slowly, across vast scales, and experiments at scale are unfeasible or unethical.
Figure from the review article showing that seed disperser decline can reduce plant biodiversity, ecosystem function, and long-term resilience of ecosystems. Relative to the baseline of high-integrity landscapes with robust seed disperser assemblages (shown at left), ecosystems within fragmented and degraded habitats (in the middle middle) have lower seed dispersal function, especially through losses of large-bodied seed dispersers; these losses reduce several aspects of ecosystem function. Habitats that are potentially suitable under future climates (at the right) for the plants at the left receive fewer seeds through dispersal, reducing gene flow and threatening the capacity of ecosystems to adapt to climate change.
Seed disperser decline threatens plant biodiversity, connectivity, and resilience.
Yet despite these being core goals of global efforts to protect, manage, and restore nature, the roles of seed dispersers remain largely overlooked in global biodiversity and restoration strategies.
Figure from the review article with several panels. The first shows declines in seed disperser species richness, body mass, movement, range size, and population size spanning ~6% to ~30% for each. The next shows that seed disperser species have higher proportions of threatened and endangered species than other groups of animals. The last three panels show maps of mammalian seed disperser losses due to extinction, losses and gains of range size, and potential losses of endangered animals. For each of these three maps, most regions have substantially lost seed dispersers, have seed dispersers that exist in smaller ranges, or have many endangered seed dispersers.
The majority of plant species rely on animals to move their seeds. Birds, mammals, and other seed dispersers shape plant biodiversity, recovery from disturbance, and responses to climate change.
But this is breaking down as seed disperser diversity, abundance, and movement decline worldwide.
Pollinator decline has captured global attention, but another plant-animal mutualism is quietly unraveling.
Our new Nature Reviews Biodiversity article synthesizes global evidence on seed disperser decline and what it means for plant biodiversity, ecosystem recovery, and climate adaptation. 🧵