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Microclimate buffering and vegetation patterns at karst cave entrances: a pilot study in Tràng An, Vietnam

Vuorimäki, Elsa LU (2026) NGEK11 20261
Department of Earth and Environmental Sciences (MGeo)
Abstract
Karst caves are known to buffer external climatic variability and track annual temperature and humidity means, yet little is understood about how this buffering extends beyond cave interiors or whether it influences vegetation patterns at cave entrances. This pilot study investigates microclimate (temperature, relative humidity and derived vapour pressure deficit) and vegetation patterns (Shannon diversity and species richness) along entrance transects at three single‑entrance caves in the Tràng An Landscape Complex, northern Vietnam, during the cool‑dry season (January 2026). Microclimate was recorded at five‑minute resolution using dataloggers placed inside the cave, at the entrance, and along outward transects, accompanied by a control... (More)
Karst caves are known to buffer external climatic variability and track annual temperature and humidity means, yet little is understood about how this buffering extends beyond cave interiors or whether it influences vegetation patterns at cave entrances. This pilot study investigates microclimate (temperature, relative humidity and derived vapour pressure deficit) and vegetation patterns (Shannon diversity and species richness) along entrance transects at three single‑entrance caves in the Tràng An Landscape Complex, northern Vietnam, during the cool‑dry season (January 2026). Microclimate was recorded at five‑minute resolution using dataloggers placed inside the cave, at the entrance, and along outward transects, accompanied by a control reference at the base of the doline slope and regional weather‑station data. Vegetation was surveyed using 1 × 1 m quadrats positioned along the same transects to ensure spatial comparability.
All caves exhibited strong thermal and humidity buffering, with interior conditions showing minimal diurnal variation and clear decoupling from external conditions. The buffering effect was spatially concentrated at the cave threshold, and VPD buffering changed little with increasing distance from the entrance, aside from a modest gradual decrease toward the cliff edge. External VPD at the control site occasionally approached elevated evaporative‑demand levels during the measurement period, while loggers placed at the cave-transects did not exceed such levels. Differences in buffering strength between caves appear to reflect mechanisms covered in previous studies, such as thermal inertia of rock mass, heat conductivity, single‑entrance geometry, slope‑driven airflow, and humidity‑related latent heat effects.
Vegetation patterns varied between caves: diversity and richness decreased outward at one cave but increased outward at the other two. These contrasting patterns did not align with the broadly similar microclimate gradients, suggesting that structural factors such as overhang geometry, light availability, and substrate depth exert stronger control on vegetation than microclimate during the cool‑dry season. The study provides a temporally detailed baseline in the cool-dry season for future multi‑season assessments of cave‑entrance microclimates in tropical karst systems. (Less)
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author
Vuorimäki, Elsa LU
supervisor
organization
course
NGEK11 20261
year
type
M2 - Bachelor Degree
subject
keywords
cave microclimate, microclimate buffering, cave entrance, vapour pressure deficit, temperature buffering, humidity buffering, vegetation patterns, species diversity, Shannon diversity index, tropical karst, Tràng An, Vietnam, microrefugia, karst dolines
language
English
id
9236412
date added to LUP
2026-06-16 09:27:48
date last changed
2026-06-16 09:27:48
@misc{9236412,
  abstract     = {{Karst caves are known to buffer external climatic variability and track annual temperature and humidity means, yet little is understood about how this buffering extends beyond cave interiors or whether it influences vegetation patterns at cave entrances. This pilot study investigates microclimate (temperature, relative humidity and derived vapour pressure deficit) and vegetation patterns (Shannon diversity and species richness) along entrance transects at three single‑entrance caves in the Tràng An Landscape Complex, northern Vietnam, during the cool‑dry season (January 2026). Microclimate was recorded at five‑minute resolution using dataloggers placed inside the cave, at the entrance, and along outward transects, accompanied by a control reference at the base of the doline slope and regional weather‑station data. Vegetation was surveyed using 1 × 1 m quadrats positioned along the same transects to ensure spatial comparability.
All caves exhibited strong thermal and humidity buffering, with interior conditions showing minimal diurnal variation and clear decoupling from external conditions. The buffering effect was spatially concentrated at the cave threshold, and VPD buffering changed little with increasing distance from the entrance, aside from a modest gradual decrease toward the cliff edge. External VPD at the control site occasionally approached elevated evaporative‑demand levels during the measurement period, while loggers placed at the cave-transects did not exceed such levels. Differences in buffering strength between caves appear to reflect mechanisms covered in previous studies, such as thermal inertia of rock mass, heat conductivity, single‑entrance geometry, slope‑driven airflow, and humidity‑related latent heat effects.
Vegetation patterns varied between caves: diversity and richness decreased outward at one cave but increased outward at the other two. These contrasting patterns did not align with the broadly similar microclimate gradients, suggesting that structural factors such as overhang geometry, light availability, and substrate depth exert stronger control on vegetation than microclimate during the cool‑dry season. The study provides a temporally detailed baseline in the cool-dry season for future multi‑season assessments of cave‑entrance microclimates in tropical karst systems.}},
  author       = {{Vuorimäki, Elsa}},
  language     = {{eng}},
  note         = {{Student Paper}},
  title        = {{Microclimate buffering and vegetation patterns at karst cave entrances: a pilot study in Tràng An, Vietnam}},
  year         = {{2026}},
}