A University of Kentucky Martin-Gatton College of Agriculture Food and Environment faculty member is embarking on a groundbreaking study to understand the impact of climate change on Tropical Montane Cloud Forests (TMCFs) — a forest with a low-level mossy cover, generally in the tropical and subtropical regions. The study was motivated by the alarming indications that these mist-enveloped ecosystems are at serious risk from climate change. 

Leading the charge is UK Department of Forestry and Natural Resources associate professor Sybil Gotsch. A significant research focus is the role of epiphytes—non-parasitic plants that adorn TMCF trees—which play a crucial role in maintaining the ecosystem's health. Recent findings reveal that their abundance is dwindling due to climate change, a concerning trend that could have far-reaching consequences for regional forest health and water resources.  

"We're deeply invested in understanding how epiphyte loss, under the influence of climate change, affects the tree function and forest water cycling," Gotsch said. "This isn't just about understanding ecosystem biology; we recognize that this system will be changing and those changes will have real impacts on wildlife, as well as human populations, that depend on these water resources. We hope that our results clarify how changes in climate will impact the forest so conservation scientists and natural resource managers can incorporate these findings into future management strategies.” 

Gotsch’s team, in collaboration with researchers from the University of California-Berkeley, Wake Forest University and the University of Utah, is conducting an innovative "epiphyte stripping" experiment in Costa Rica. Selected trees are completely divested of their epiphytes, enabling researchers to study the effects on tree physiology and forest health — making this the first large-scale experiment of its kind.  

"We're going to study the environment around the top part of trees, like the air temperature, moisture and sunlight. We'll also look at how these trees grow, use water and how water moves inside them,” Gotsch explained. “We're comparing trees that have and haven’t had their extra plants (epiphytes) removed. Since we believe that certain forests might reduce in size because of fast-changing climate conditions, it's important to know how losing these plants affects the overall health and water usage of trees.” 

For the experiment, 20 trees—divided between forest and pasture settings—are being studied. Half of each group undergoes epiphyte removal, with the other half serving as a control. Sap flow probes, made at UK in collaboration with electrical engineering professor Janet Lumpp, and microclimate sensors are used to gather comprehensive data on factors ranging from temperature and humidity to transpiration. The removed epiphytes will be repurposed in educational gardens, promoting research and environmental awareness. 

Due to their critical roles in regional water cycling and exceptionally high biodiversity and endemism (state of being a species found in a single defined geographic location), TMCFs are vital ecosystems to study and preserve. While their inaccessibility has provided some de facto protection, lowland deforestation and rising global sea surface temperatures indirectly threaten these forests by lowering cloud cover and worsening drought. The most susceptible ecosystem components are the epiphytes, which cover nearly all tree surfaces in the TMCF and contribute significantly to ecosystem function.  

Gotsch says the loss of tropical montane ecosystem function would have severe consequences for biodiversity along with the stability of water supplies.  

“Tropical montane ecosystems, often known as cloud forests, are biodiversity hotspots teeming with unique species, many of which are found nowhere else on the planet. These ecosystems play a pivotal role in hydrological processes, capturing moisture from constant cloud cover and mist, which is then released into rivers and streams. This ‘cloud stripping’ function makes montane forests vital water sources for vast lowland regions and human populations.” 

The forest’s dense vegetation also helps anchor soil, reducing landslide risks and erosion. Additionally, it acts as a significant carbon sink by capturing and storing carbon dioxide from the atmosphere. 

These ecosystems contribute economically through eco-tourism and the supply of non-timber forest products, crucial for local livelihoods. The degradation or loss of these ecosystems would thus not only imperil biodiversity but also impact human societies. 

“This research is unprecedented in scale and significance,” Gotsch said. "Its findings will be invaluable to land managers, conservationists and policymakers in tropical montane regions, guiding efforts to ensure the region's long-term water supply.” 

Once complete, Gotsch’s group will analyze the data. Preliminary expectations suggest trees stripped of epiphytes may exhibit signs of stress, including increased canopy temperatures and reduced moisture levels. 

Beyond its immediate findings, this study potentially holds broader implications for forest management and conservation efforts. Gotsch believes as climate change continues to reshape ecosystems worldwide, understanding how these changes affect the intricate relationships within these environments is paramount. The experiment results may inform conservation strategies and emphasize the importance of preserving epiphyte-rich ecosystems while adapting to the challenges posed by climate change. 

“As global challenges mount, initiatives like these offer a beacon of hope,” Gotsch said. “I’m glad that UK stands at the forefront, championing research that intertwines science, education and sustainability to foster a more resilient future.”

To learn more about Gotsch's work, visit https://www.sybilgotsch.com/. 

Research reported in this publication was supported by the National Science Foundation under Award Number 2130110. The opinions, findings, and conclusions or recommendations expressed are those of the author(s) and do not necessarily reflect the views of the National Science Foundation. 

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