Cloud Forests on the Move: How Climate and Deforestation Are Forcing Plants Uphill in Mesoamerica

Redacción HC
15/04/2025

Cloud forests—those misty, lush ecosystems clinging to the slopes of Central America’s mountains—are not standing still. A sweeping study published in Science (March 2025) reveals that plant species in Mesoamerican cloud forests are shifting their ranges upslope at alarming rates, driven by the twin forces of climate change and deforestation.

Researchers led by Santiago Ramírez-Barahona (UNAM) and Emily Hollenbeck (University of Miami), in collaboration with global institutions, analyzed more than 360,000 plant occurrence records from 1,021 species over four decades. Their conclusion is both sobering and urgent: plants are moving uphill at an average pace of 1.8 to 2.7 meters per year, and in some cases, their suitable habitat is shrinking from both above and below.

A Race Against Altitude: Why Cloud Forests Are So Vulnerable

Cloud forests are ecological treasures. Straddling elevations from 1,200 to 3,500 meters, they are hotspots of biodiversity and sources of water regulation for millions of people. Yet they are also inherently fragile—confined to narrow altitude bands and highly sensitive to temperature and moisture shifts.

“These forests can't move sideways. Their only option is up—and eventually, there’s nowhere else to go,” said Ramírez-Barahona in a statement to Science News.

Warming temperatures are pushing climatic envelopes uphill. At the same time, deforestation at mid-elevations erodes the “ladder” that plants might use to migrate, causing habitat bottlenecks and potential extinctions.

The Science Behind the Shift: Tracking Plants Over 40 Years

The research team used an observational longitudinal approach:

• Data set: Over 360,000 georeferenced records from herbarium specimens and field surveys (1979–2023).
• Analysis: Altitudinal boundaries for each species were calculated and compared over time to assess range shifts.
• Environmental variables: Temperature rise, precipitation patterns, forest loss, and fragmentation.

Findings showed that:

• Lower elevation limits moved upslope by 1.8–2.7 meters per year.
• Upper elevation limits also moved up, but often more slowly—creating range contractions.
• In areas of intense deforestation, species were pushed downwards at rates of up to 6.3 m/year—a rare and concerning inversion of typical climate migration patterns.

“It’s not just that species are moving—many are losing ground at both ends,” noted Hollenbeck.

Main Findings: What the Data Reveals

1. Widespread Altitudinal Migration

Across Mesoamerica, most plant species showed consistent upslope shifts, with the fastest shifts seen in temperature-sensitive montane species.

2. Range Contraction

As plants climb, they lose range area—some species are effectively being squeezed out of existence. Endemic species with narrow ranges are particularly at risk.

3. Climate vs. Land Use

While climate change is the dominant driver, the impact of deforestation is more spatially intense—especially in Guatemala, southern Mexico, and parts of Honduras.

4. Cloud Forests Have a Ceiling

Unlike lowland forests, cloud forests can’t expand upward indefinitely. At a certain point, mountaintops simply run out of space.

5. Comparable Global Trends

The study echoes findings from African and Southeast Asian mountain ecosystems, but in Mesoamerica, the combination of warming and land-use change makes the crisis more acute.

What This Means for Conservation and Policy

Conservation Strategies

• Establish altitudinal corridors: Protected areas must be connected across elevation gradients to facilitate species migration.
• Target reforestation: Focus especially on degraded mid-elevation zones where upslope movement is blocked.

Policy Implications

• Reframe protected area design: Expand vertical coverage, not just horizontal.
• Incorporate altitude in national biodiversity monitoring: Most conservation metrics don’t yet include vertical movement.

Ecosystem Services at Risk

Cloud forests are natural water towers, affecting drinking water, agriculture, and aquifer recharge. Their decline could have cascading socioeconomic impacts across the region.

“This isn’t just a biodiversity crisis—it’s a water security issue,” emphasized the study’s authors.

Urgent Recommendations

1. Expand climate-smart conservation networks, with special attention to mountainous terrain.
2. Halt deforestation at lower elevations to remove barriers to species movement.
3. Monitor associated fauna and soil systems to assess whole-ecosystem responses.

These actions require regional coordination, as cloud forest ranges cross national borders. Mexico, Guatemala, and Costa Rica are key players in building transboundary conservation frameworks.

Final Thoughts: A Green Exodus to the Mountaintops

The image is haunting: plants quietly climbing mountain slopes, step by step, year by year—until the mountain ends. The race is not only biological, but also political, economic, and moral.

If governments and conservationists act now, there's still a chance to build lifelines for these forests in the sky. But time is short, and the climb is steep.

Topics of interest

Biodiversity