Population structure of the Mexican baldcypress (Taxodium mucronatum Ten.) in Queretaro, Mexico

The Ahuehuete or Mexican baldcypress (Taxodium mucronatum Ten.) is an important tree species of the riparian gallery forests of México and Guatemala. This study is the first demographic survey of T. mucronatum in the Central State of Querétaro, México. Populations with more than 200 individuals having a diameter at breast height > 10 cm, were surveyed by contiguous quadrats (10 m × 10 m) within (100 m × 20 m) belt transects where all individuals including seedlings were tagged and measured. Annual radial growth, seed production, germination and survival data were recorded to construct transition matrices per population. The populations were distributed in the major rivers of the Mexican Plateau and the Sierra Madre Oriental between 1100 and 2460 m above sea level, with densities averaged 250 trees per hectare. The structure of the populations indicated gaps in the juvenile classes and low recruitment. Populations in disturbed habitats had significantly decreasing growth rates (due to high seedling mortality) for the years 1999–2000 (λ = 0.94) while healthy populations were stables in time, and did not differ significantly from replacement (λ = 1, a population with equal number of deaths and germinants). Trees in polluted rivers with controlled flow have significantly smaller radial growth and smaller canopy than those in better conditions such as free flowing rivers and permanently flooded areas.