Vascular Epiphyte Ecology in Tropical Forests

Vascular epiphytes are non-parasitic, structurally dependent plants that inhabit the surfaces of trees and shrubs in humid tropical forests, contributing up to 40% of local vascular plant diversity in some regions. Predominant groups include orchids, bromeliads, ferns and aroids, which exploit a three-dimensional canopy matrix for light, water and nutrient acquisition. Rather than relying on soil, these plants intercept moisture and nutrients from rain, mist and canopy debris, forming suspended soils that support rich microbial communities. Their distribution and abundance are shaped by climatic gradients (humidity, precipitation and temperature), host traits (bark texture, branch architecture and leaf phenology), elevation and latitudinal position. Vascular epiphytes perform key ecosystem functions: they enhance canopy water storage, mediate nutrient cycling through litter traps and stemflow enrichment, and create microhabitats for invertebrates and microflora. Dispersal limitation and host specificity further structure epiphyte assemblages, yielding high beta diversity across spatial scales. As indicators of forest health, epiphytes are particularly vulnerable to climate change, forest fragmentation and altered hydrological regimes. Conservation of their diverse assemblages is essential for maintaining the structural complexity, biodiversity and ecosystem services of tropical forests.

Research from Nature Portfolio

Recent studies have disentangled the relative influence of abiotic and biotic drivers on epiphyte diversity along mountain transects. Air humidity emerged as the strongest climatic determinant, while tree basal area was the key biotic factor directly enhancing species richness at mid-elevations. Soil moisture and nutrient availability appeared mainly as indirect influences through effects on host tree growth. Epiphyte abundance and richness followed a unimodal curve with elevation, peaking in zones where canopy humidity and large host size coincide. This work highlights the interplay of microclimatic conditions and host characteristics in shaping epiphyte assemblages and underscores the vulnerability of these communities to shifts in moisture regimes and forest structure.

Vascular Epiphyte Ecology in Tropical Forests publication trend

The graph below shows the total number of articles in vascular epiphyte ecology in tropical forests across all publications each year (not limited to Nature Index journals).

Technical terms

Vascular epiphyte: A plant that lives non-parasitically upon another plant, obtaining water and nutrients from the atmosphere and canopy debris, and possessing specialised vascular tissue.

Canopy soil: Accumulations of organic matter, mineral particles and microbial biomass retained in the canopy by epiphytic plants and root mats, functioning similarly to ground soil.

Beta diversity: The measure of species turnover or compositional change between different habitats or spatial locations within a region.

Crassulacean acid metabolism (CAM): A photosynthetic adaptation in which stomata open at night to reduce water loss, common among epiphytic plants in humid and seasonally dry environments.

References

1. Urban epiphytes: Bromeliad diversity in a green cover gradient across a Neotropical streetscape. Urban Forestry & Urban Greening (2023).
2. Suspended soils enrich local forest floor soils during the rainy season in a tropical monsoon rainforest of Hainan Island, South China. Frontiers in Plant Science (2024).
3. Vascular epiphytes contribute disproportionately to global centres of plant diversity. Global Ecology and Biogeography (2021).
4. Distribution of vascular epiphytes along a tropical elevational gradient: disentangling abiotic and biotic determinants. Scientific Reports (2016).
5. Host specificity in vascular epiphytes: a review of methodology, empirical evidence and potential mechanisms. AoB Plants (2015).
6. Host tree phenology affects vascular epiphytes at the physiological, demographic and community level. AoB Plants (2015).
7. Climate, as well as branch-level processes, drive canopy soil abundance and chemistry. Geoderma (2023).