Silver W.L., Kuppers L.M., Lugo A.E. et al. Carbon Sequestration and Plan Community Dynamics Following Reforestation of Tropical Pasture. Ecological Applications, Vol 14(4), 2004 pp 1115-1127.
Conversion of abandoned cattle pastures to secondary forests and plantations
in the tropics has been proposed as a means to increase rates of carbon (C) sequestration
from the atmosphere and enhance local biodiversity. We used a long-term tropical reforestation
project (55–61 yr) to estimate rates of above- and belowground C sequestration
and to investigate the impact of planted species on overall plant community structure.
Thirteen tree species (nine native and four nonnative species) were planted as part of the
reforestation effort in the mid to late 1930s. In 1992, there were 75 tree species (.9.1 cm
dbh) in the forest. Overall, planted species accounted for 40% of the importance value of
the forest; planted nonnative species contributed only 5% of the importance value. In the
reforested ecosystem, the total soil C pool (0–60 cm depth) was larger than the aboveground
C pool, and there was more soil C in the forest (102 6 10 Mg/ha [mean 6 1 SE]) than in
an adjacent pasture of similar age (69 6 16 Mg/ha). Forest soil C (C3-C) increased at a
rate of ;0.9 Mg·ha21·yr21, but residual pasture C (C4-C) was lost at a rate of 0.4 Mg·ha21·yr21,
yielding a net gain of 33 Mg/ha as a result of 61 years of forest regrowth. Aboveground
C accumulated at a rate of 1.4 6 0.05 Mg·ha21·yr21, to a total of 80 6 3 Mg/ha. A survey
of 426 merchantable trees in 1959 and 1992 showed that they grew faster in the second
33 years of forest development than in the first 22 years, indicating that later stages of
forest development can play an important role in C sequestration. Few indices of C cycling
were correlated with plant community composition or structure. Our results indicate that
significant soil C can accumulate with reforestation and that there are strong legacies of
pasture use and reforestation in plant community structure and rates of plant C sequestration.