Revista Chilena de Historia Natural 85 (3): 291-306, 2012
RESEARCH ARTICLE
Decoupling of soil development and plant succession along a 60000 years
chronosequence in Llaima Volcano, Chile
Few studies have investigated the long-term evolution of nutrient limitation in
ecosystems developed on volcanic soils. To approach the problem, we used “space for time substitution” to compare sites with the
same state factors, except for the time elapsed since disturbance. Forests of Conguillío National Park in southern of Chile occur on
volcanic soils that developed from lava flows and ash deposits of different ages originated from the activity of Llaima volcano. In this
study we evaluate the patterns of change in carbon, nitrogen and phosphorus in soils and leaves, as well as changes in tree diversity
and basal area along a chronosequence of volcanic substrates from 50 to 60,000 years AP (eight sites). We assessed the evolution of
N and P limitation in plants by comparing foliar N/P ratios and the efficiency in the use of nutrients through foliar C/P and C/N ratios.
Values of total C, N and P in surface soils were low in the first 250 years of succession, increasing up to a maximum concentration at
intermediate stages of succession (300-700 yr), to decline in later successional stages, a pattern also observed in a volcanic
chronosequence from Hawaii. We found a decrease in basal area and an increase in diversity of woody species in advanced stages of
the chronosequence. Foliar N and P concentrations slightly increased through the chronosequence in both evergreen and deciduous
tree species. The foliar N/P ratio did not change along the chronosequence in both deciduous and evergreen species, but differed
between evergreen and deciduous trees. The successional increase in tree diversity is explicated by a greater proportion of evergreen
angiosperms with efficient P use. Despite the retrogression phase documented by more the decrease in the total contents of N and P
in soils, we did not detect a similar decline in the foliar contents of N and P, which suggests that plant and soil nutrient contents are
decoupled.
Key words:
N/P ratio,
phosphorus, primary succession, retrogression, volcanic soils.
