• The Luquillo Mountains are affected by a wide array of environmental
processes and disturbances. Events that concurrently alter the environmental
space of several different areas of the Luquillo Mountains occur every 2 to 5
years. Events such as hurricanes that cause widespread environmental
modification occur once every 20 to 60 years.
• The most common disturbance-generating weather systems that affect the
Luquillo Mountains are (1) cyclonic systems, (2) noncyclonic intertropical
systems, (3) extratropical frontal systems, and (4) large-scale coupled ocean-
atmospheric events (e.g., North Atlantic Oscillation, El Niño-Southern Oscilla-
tion). Unlike some tropical forests, disturbances associated with the passage of
the Inter-Tropical Convergence Zone or monsoonal rains do not occur.
• Hurricanes are considered the most important natural disturbance affecting
the structure of forests in the Luquillo Mountains. Compared to other humid
tropical forests, Luquillo has a high rate of canopy turnover caused by
hurricanes but a relatively low rate caused by tree-fall gaps. Historically,
pathogenic disturbances have not been uncommon.
• Human-induced disturbances have historically included tree harvesting for
timber and charcoal, agriculture, and agroforestry. In the past few decades,
water diversions, fishing and hunting, and road building have been important
disturbances. Present and future human-induced disturbances are related to
regional land use change, the disruption of migratory corridors, and forest
drying related to coastal plain deforestation and regional climate change.
• Hurricane-related storm discharges can cause significant geomorphic
modifications to Luquillo stream channels, and stream water concentrations
of sediments and nutrients can be elevated for months to years following a
major hurricane. However, the largest floods are not necessarily associated
with hurricanes, and the annual peak discharge can occur in any month of the
year but is most common in the late summer and fall.
• Over the entire island of Puerto Rico, 1.2 landslide-producing storms occur
each year. In the Luquillo Mountains, landslides are typically covered with
herbaceous vegetation within 2 years, have closed canopies of woody
vegetation in less than 20 years, and have aboveground biomass of the
adjacent forest after several decades.