Cave Conservation and the Leave No Trace Principles
Caves are among the most fragile ecosystems on earth. A stalactite that took ten thousand years to form can be snapped off in a second. A bat colony wiped out by fungal disease will not return to a roost for decades. Unlike a forest that can regrow after a fire, a cave's biological and geological communities recover on timescales that dwarf a human lifetime. Understanding the specific threats — and the guidelines designed to address them — is the first responsibility of every person who goes underground.
White-nose syndrome and bat decontamination
White-nose syndrome (WNS) is caused by the fungus Pseudogymnoascus destructans, first detected in a New York cave in 2006. By 2024 it had spread to more than 40 US states and several Canadian provinces, killing an estimated six to seven million bats — predominantly little brown bats (Myotis lucifugus), tricolored bats, and northern long-eared bats, the last of which is now listed as federally threatened under the US Endangered Species Act. The fungus attacks bats during hibernation, irritating skin and wing membranes and disrupting torpor cycles so bats burn through fat reserves and starve before spring.
The pathogen spreads partly on cavers' gear. The US Fish and Wildlife Service and the National Speleological Society (NSS) both recommend full decontamination protocols between cave visits: brushing off all visible mud, then soaking gear in a solution of quaternary ammonium compounds (quats) at the manufacturer-recommended concentration, or a dilute bleach solution (1 part bleach to 9 parts water) for a minimum of 10 minutes. Heat treatment at 50°C for 20 minutes is effective for items that can tolerate it. Gear should be air-dried before re-use. The US Bureau of Land Management (BLM) enforces cave-closure orders at hibernacula between October and April; these closures must be respected even when physical barriers are absent.
Microclimate disturbance
The air inside a cave is a closed or semi-closed system. Temperature, humidity, and carbon dioxide levels are stabilised by the cave's connection to the surface and by the thermal mass of surrounding rock. A group of ten people introduces body heat, exhaled CO2, and moisture that measurably alters these parameters for hours after they leave. In Lascaux, France — whose Palaeolithic paintings forced permanent closure in 1963 — mass tourism caused CO2 concentrations to spike, encouraging the growth of green algae on the walls. The microclimate lesson from Lascaux is unambiguous: human presence has consequences that outlast the visit.
Cavers can reduce microclimate impact by keeping group sizes small (most protected wild caves in the US have group-size limits of six to eight, managed by NSS grottoes and BLM permit systems), by limiting time in confined areas, and by avoiding prolonged rest in tight passages where exhaled air cannot disperse. In show caves, operators who have invested in metered ventilation systems demonstrate that the tension between access and preservation is manageable — but it requires active management.
Lampenflora and the algae problem
Lampenflora is the collective term for photosynthetic organisms — algae, mosses, cyanobacteria — that colonise rock surfaces near artificial light sources. In show caves, where tungsten and fluorescent lights were standard for most of the twentieth century, lampenflora created green and black halos around every fixture. The organisms penetrate mineral surfaces through biofilm acids, physically degrading speleothems. A switch to LED lighting has helped, both because LEDs generate less heat and because their spectra can be tuned to reduce photosynthetically active radiation. But removal of established lampenflora requires careful biocide treatment followed by mechanical cleaning — a costly process that Cueva de Nerja in Spain, Postojna in Slovenia, and Wookey Hole in England have all undertaken.
Wild cavers contribute to the problem when they rest headlamps directly against cave walls. The NSS guidelines recommend against resting lights on formations and against allowing lamp beams to dwell on the same surface for extended periods in biologically sensitive areas.
Cave-soil compaction and trail management
Cave sediments — silts, clays, guano deposits, and flowstone floors — are archives of palaeoclimate data, archaeological artefacts, and invertebrate habitat. The bones of extinct megafauna recovered from Naracoorte Caves in South Australia and Kents Cavern in Devon were preserved precisely because foot traffic was absent for millennia. Compaction from boots destroys soil porosity, alters drainage, and physically disturbs artefacts. NSS conservation guidelines identify staying on established trails as the single highest-impact habit a caver can adopt.
In wild-cave contexts where no trail exists, cavers are taught to move on bare rock where possible, to avoid muddy banks, and never to step on speleothems regardless of how robust they appear. In managed cave systems administered by the BLM under the Federal Cave Resources Protection Act of 1988, off-trail travel requires explicit permit conditions.
Urine, water tables, and soluble chemistry
Human urine introduces urea, ammonia, and a suite of salts into cave hydrology. In vadose (above water table) cave streams these compounds concentrate during low-flow periods and alter the chemical balance that governs speleothem growth. In caves with tourist infrastructure but no toilet facilities, the cumulative impact can shift the carbonate chemistry enough to inhibit new speleothem precipitation. The NSS recommends collecting urine in sealed containers and removing it from the cave; improvised urination even in "out-of-the-way" spots is explicitly discouraged in NSS grottos' code of conduct. Several wilderness caves in the US have adopted mandatory pee-bottle requirements for permitted trips.
The NSS and BLM frameworks
The National Speleological Society publishes a conservation pledge that underpins responsible caving in the United States: "Take nothing but pictures, leave nothing but footprints, kill nothing but time." The BLM's Cave Management Policy (Instruction Memorandum No. 2009-011) establishes a tiered permit system for significant caves — a designation covering roughly 800 federally managed caves — and mandates conservation assessments before any new access or development. Significant Caves require an approved Cave Management Plan before permits are issued. The interaction between NSS grottos (local clubs) and BLM field offices is the practical mechanism by which most US wild-cave access is managed.
Internationally, cave conservation sits within IUCN's Protected Areas framework. Several UNESCO World Heritage cave systems — Mammoth Cave, Carlsbad Caverns, Naracoorte, the South China Karst, Phong Nha-Ke Bang — carry specific management obligations that restrict access and mandate monitoring.
What you can do
Following decontamination protocols between caves, staying on marked routes, keeping group sizes within permitted limits, removing all waste including human waste, and reporting damage to operators or the relevant land-management agency are the core actions. They are not onerous. The cave that benefits most from your restraint may be one you will never personally visit — but it will exist for the next person, and for the person after them.
Joining an NSS grotto, BCA club, or equivalent national organisation also makes a direct contribution: club members support advocacy for cave protection, participate in conservation workdays to restore damaged surfaces and remove introduced materials, and contribute survey data to the national cave databases that inform land-management decisions. Caves that are surveyed, documented, and actively managed by local grotto communities are substantially better protected than caves with no community presence. The single most effective conservation act any new caver can perform is joining their regional club.
Find caves with visitor infrastructure, guided tours, and conservation ratings on the cave map.