Monitoring population viability in declining tree species using indicatorsof genetic diversity and reproductive success

Biodiversity monitoring involves recurrent observations and recording chang es and trends based on established biological benchmarks. The development o f biological indicators at each level of the biodiversity hierarchy (landsc ape, community, species/genetic) is required to monitor and assess human im pacts on natural populations and habitats. Genetic diversity is the ultimat e source of biological diversity, providing the raw material for adaptation , evolution and survival of individuals and species - and becomes especiall y important to species survival in changing environments. Some indicators f or monitoring population viability (which are defined here in the narrow se nse as genetic diversity and reproductive success) in small, isolated popul ations of white pine, Finns strobus L., red pine, Pinus resinosa Ait., and white spruce, Picea glauca (Moench) Voss, from the Island of Newfoundland ( NF), Canada, are discussed as examples for monitoring the effects of small population size and increasing fragmentation on genetic diversity and repro ductive behavior. Results with these populations suggest that reproductive success may provide better indicators for monitoring the effects of recent population declines, particularly in the early phases of population decline , than many of the standard genetic indicators.