Data from: Factors explaining variability in woody above-ground biomass accumulation in restored tropical forest

Secondary forests comprise an increasing area of the tropics and play an
important role in global carbon cycling. We compare above-ground biomass
accumulation of both planted and naturally regenerating trees, as well as
C in the top soil layer, in three restoration treatments replicated at 14,
six to eight year old restoration sites in southern Costa Rica.
Restoration strategies include: control (no planting), planting tree
islands, and conventional, mixed-species tree plantations. We evaluate the
importance of past land-use, soil nutrients, understory cover, and
surrounding forest cover in explaining variation in above-ground biomass
accumulation (ABA) rate across sites. Total ABA and planted tree ABA rate
were highest in plantations, intermediate in islands, and lowest in
control treatments, whereas ABA rate of naturally regenerating trees did
not differ across treatments. Most ABA in plantations (89%) and islands
(70%) was due to growth of planted trees. Soil carbon did not change
significantly over the time period of the study in any treatment. The
majority of across-site variation in both total and planted tree ABA rate
was explained by duration of prior pasture use. Tree growth in the first
two years after planting explained approximately two-thirds of the
variation in ABA rate after 6–8 years. Soil nutrient
concentrations explained relatively little of the variation in planted or
naturally recruiting ABA rate. Our results show that planting trees
substantially increases biomass accumulation during the first several
years of forest recovery in former agricultural lands and that past-land
use has a strong effect on the rate of biomass accumulation. Planting tree
islands is a cost-effective strategy for increasing ABA and creating more
heterogeneous habitat conditions than tree plantations. We recommend small
scale planting trials to quickly assess potential biomass accumulation and
prioritize sites for ecosystem service payments for carbon sequestration.